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JP,09-237399,A(1997)




              PATENT ABSTRACTS OF JAPAN

                 (11)Publication number :                 09-237399
                 (43)Date of publication of application : 09.09.1997


(51)Int.Cl.                       G08G 1/042
                                  B60R   21/00
                                  G01R   33/02
                                  G01V    3/08
                                  G01V    3/10
                               // G01C   21/00



(21)Application number : 08-0439 (71)Applicant : CANON ELECTRON
                         33                      INC
(22)Date of filing :     01.03.19 (72)Inventor : KAWASE MASAHIRO
                         96                      TAZAKI SHINICHI


(54) METHOD, DEVICE AND SYSTEM FOR VEHICLE DETECTION
                    (57)Abstract:
                    PROBLEM TO BE SOLVED: To improve reliability by
                    making the magnetic detection of an vehicle highly
                    precise through the use of a magnetic sensor consisting
                    of plural small magnetic detection elements.
                    SOLUTION: The magnetic sensor 12 plurally arranging
                    along the longitudinal direction of the vehicle the
                    magnetic detection elements 1A to 11N with magnetic
                    field detecting sensitivity in a direction vertical to the
                    ground is installed on or in the ground within the
                    passing width of the vehicle. Through the use of a
selector 21, a timer counter 20 and RAM 26 storing the early value of
external magnetic intensity, a control part 19 measures each change of
external magnetic field intensity basing on the state of no vehicle with
respect to each magnetic detection element as a reference based on the
intensity of external magnetic field detected by each magnetic detection
element. Then the part 19 judges vehicle detection depending on whether
the total sum of the respective absolute values of the measured values
exceeds a prescribed combined threshold values.




CLAIMS


[Claim(s)]
[Claim 1]In a vehicle detecting method which detects a magnetic field
generated from vehicles with a magnetic sensor, and detects vehicles
magnetically, A magnetic sensor which put in order two or more
magnetism detecting elements which have magnetic field detection
sensitivity in the direction vertical to a ground surface along with a vehicles
longitudinal direction is installed in a ground surface in a band pass of
vehicles, or underground, A vehicle detecting method detecting vehicles by
the judgment of whether external magnetic field intensity change as on the
basis of the state where each of two or more of said magnetism detecting
elements detects external magnetic field intensity, and there are no
vehicles is measured, and total of an absolute value of two or more
measurement values of this measuring result exceeds predetermined joint
threshold                                S.
[Claim 2]The vehicle detecting method according to claim 1 setting said
joint threshold S as a value of a product which hung threshold s in the
case of one magnetism detecting element, and a square root of the
addition numbers n of said measurement value added in order to ask for
said                                 total.
[Claim 3]An absolute value of two or more measurement values of a
measuring result of the aforementioned external magnetic field intensity
change is arranged in descending, it is considered as |deltaH(k) | (k= 1,
2, ordinal number of --), and they are the following expression about this
value, threshold s in the case of one magnetism detecting element, and a
square root of said addition numbers n. [Mathematical formula 1]
The vehicle detecting method according to claim 2 judging with having
detected vehicles when it compared whether it is alike, it would set, would
substitute one by one from k= 1, and the above-mentioned expression
would be satisfied and the above-mentioned expression was satisfied.
[Claim 4]The vehicle detecting method according to claim 2 or 3 setting
threshold s in the case of said one magnetism detecting element as the
range                of              0.05-0.1              gauss.
[Claim 5]It is a vehicle detecting device which detects a magnetic field
generated from vehicles with a magnetic sensor, and detects vehicles
magnetically, A magnetic sensor which consists of two or more magnetism
detecting elements arranged so that it may have magnetic field detection
sensitivity in the direction vertical to a ground surface and may rank with a
ground surface in a band pass of vehicles, or underground along with a
vehicles longitudinal direction, A measurement means which measures
each of external magnetic field intensity change as on the basis of the
state where there are no vehicles to each magnetism detecting element,
based on external magnetic field intensity detected by each of two or more
of said magnetism detecting elements, A vehicle detecting device having a
judging means which judges vehicle detection by whether total of each
absolute value of a measurement value of external magnetic field intensity
change measured by this measurement means exceeds predetermined
joint                    threshold                   S.
[Claim 6]It has a memory measure which memorizes a value of external
magnetic field intensity detected by said two or more magnetism detecting
elements in the state where said measurement means does not have
vehicles as an initial value used as a standard, The vehicle detecting
device according to claim 5 measuring the aforementioned external
magnetic field intensity change on the basis of an initial value memorized
to             this              memory             measure.
[Claim 7]A Colpitts oscillator in which said magnetism detecting element
incorporated a magnetic impedance component which attached a coil, It
comprises a comparator [ predetermined comparison voltage / output / of
a detector circuit which detects an output of this oscillator and this
detector circuit ], By detecting external magnetic field intensity, applying
an AC bias magnetic field to said magnetic impedance component with
said coil, A Pulse-Density-Modulation output in which a pulse which is two
kinds from which pulse width differs according to external magnetic field
intensity in an output of said comparator appears by turns is obtained, The
vehicle detecting device according to claim 5 or 6, wherein said
measurement means measures external magnetic field intensity change as
on the basis of the state where ask for data of a difference of pulse width
of two kinds of said pulses as external magnetic field strength data, and
said    vehicles    cannot     be  found    based     on    this    data.
[Claim 8]It is a vehicle detection system which carries out vehicle
detection to any 1 clause from Claim 5 to 7 using a vehicle detecting
device of a description, A judging means which judges whether whether
vehicles advanced on a magnetic sensor, whether it stopped on a
magnetic sensor based on a decided result of vehicle detection by a
judging means of said vehicle detecting device, and on a magnetic sensor
were left, Car presence information on a purport that vehicles have
stopped on a magnetic sensor based on a decided result of this judging
means, And a vehicle detection system characterized by having an output
means to which vehicles output **** information on a purport that on a
magnetic sensor was left, and enabling it to manage parking vehicles with
the output of said car presence information and **** information.


DETAILED DESCRIPTION


[Detailed         Description        of        the      Invention]
[0001]
[Field of the Invention]This invention detects the magnetic field generated
from vehicles, such as a car, with a magnetic sensor, and detects vehicles
magnetically, namely, relates to the vehicle detecting method which
detects the existence of vehicles thru/or passage, a vehicle detecting
device,        and      a       vehicle       detection      system.
[0002]
[Description of the Prior Art]Conventionally, the sensor which detects
vehicles, such as a car, is used in the use of measuring the distinction of
the existence of parking in the managerial system of a motor pool, and the
traffic    of    the    vehicles    in   a   traffic   control    system.
[0003]Usually, since vehicles, such as a car, are tinged with magnetism
using the metallic material which is easy to be tinged with magnetism, such
as a steel plate, it is detecting the magnetic field generated from vehicles
with a magnetic sensor, and it is possible to recognize existence of
vehicles                     or                   passage.
[0004]Conventionally, in the motor pool, the loop coil type magnetic
sensor was buried in the earth, and it has been used for vehicle detection
in it. A loop coil type magnetic sensor is that generate a magnetic field by
an eddy current in the metal part of the body of vehicles to the alternating
current sent through a coil, or the magnetic field from the body's own
magnetization interlinks with a loop coil, A coil's own inductance changes,
it is changed as change of oscillating frequency or amplitude in a circuit,
and vehicle detection is performed by the existence of the change.
[0005]However, although the loop coil type magnetic sensor is spreading
by detection of vehicles, it has the following problems.
[0006]- Since a loop coil opens an interval a little with vehicles and is
installed, in order to detect the inductance variation in vehicles existence,
there is the necessity of enlarging size of a sensitivity secured upper coil
(about                                 1mx1m).
[0007]- If metal bodies, such as a steel rod, are in the neighborhood, S/N
cannot               be             taken              enough.
[0008]- Since a loop coil is large and power consumption is large, it is not
fit        for         continuous         energization         use.
[0009]- A coil is a size which is about 1mx1m, and the burden of
construction expense is heavy in subterranean installation.
[0010]Then, although the small magnetic sensor was used and the
substitution was considered, When the magnetic field generated from a
vehicles pars basilaris ossis occipitalis was measured, near the zero
crossing point which remarkable unevenness is made to distribution of
magnetic field strength, and magnetic field polarity reverses by the local
magnetization of Body Manufacturing Division article each which it has, it
turned out that the dead point which does not exceed a threshold required
for     the      judgment      of     vehicle    detection      arises.
[0011]
[Problem to be solved by the invention]Then, a reliable vehicle detecting
method in which SUBJECT of this invention can perform magnetic
detection of vehicles with high precision using the magnetic sensor which
consists of two or more small magnetism detecting elements, And it is in
providing the vehicle detection system which is a vehicle detecting device
which performs vehicle detection by the method, can attain a
miniaturization and can be used effective in management of parking
vehicles using the vehicle detecting device of low power consumption, and
this            vehicle               detecting              device.
[0012]
[Means for solving problem]In the vehicle detecting method which
according to this invention detects the magnetic field generated from
vehicles with a magnetic sensor, and detects vehicles magnetically in order
to solve above-mentioned SUBJECT, The magnetic sensor which put in
order two or more magnetism detecting elements which have magnetic
field detection sensitivity in the direction vertical to a ground surface along
with the vehicles longitudinal direction is installed in the ground surface in
the band pass of vehicles, or underground, The external magnetic field
intensity change as on the basis of the state where each of two or more of
said magnetism detecting elements detects external magnetic field
intensity, and there are no vehicles was measured, and the method of
detecting vehicles by the judgment of whether total of the absolute value
of two or more measurement values of this measuring result exceeds
predetermined       joint    threshold      S       was      adopted.
[0013]According to such a vehicle detecting method, the influence of the
zero crossing point which the magnetic field polarity looked at by
distribution of the magnetic field strength in the case of measuring the
magnetic field generated from a vehicles pars basilaris ossis occipitalis
reverses can be avoided, and highly precise and reliable vehicle detection
can                     be                   performed.
[0014]According to this invention, it is a vehicle detecting device which
detects the magnetic field generated from vehicles with a magnetic sensor,
and detects vehicles magnetically, The magnetic sensor which consists of
two or more magnetism detecting elements arranged so that it may have
magnetic field detection sensitivity in the direction vertical to a ground
surface and may rank with the ground surface in the band pass of
vehicles, or underground along with a vehicles longitudinal direction, The
measurement means which measures each of external magnetic field
intensity change as on the basis of the state where there are no vehicles to
each magnetism detecting element, based on the external magnetic field
intensity detected by each of two or more of said magnetism detecting
elements, Total of each absolute value of the measurement value of
external magnetic field intensity change measured by this measurement
means adopted the composition of the vehicle detecting device which has
a judging means which judges vehicle detection by whether predetermined
joint         threshold          S           is        exceeded.
[0015]While being able to perform reliable vehicle detection with high
degree of accuracy with the vehicle detecting method of this invention
according to such composition, the magnetic sensor can consist of small
size which consists of plurality of the small magnetism detecting element
constituted, for example using the magnetic impedance component as a
magnetic       sensor      of       low       power     consumption.
[0016]It is a vehicle detection system which performs vehicle detection
using the vehicle detecting device by above-mentioned this invention
according to this invention, The judging means which judges whether
whether vehicles advanced on the magnetic sensor, whether it stopped on
the magnetic sensor based on the decided result of the vehicle detection
by the judging means of said vehicle detecting device, and on the
magnetic sensor were left, The car presence information on the purport
that vehicles have stopped on a magnetic sensor based on the decided
result of this judging means, And it has an output means to which vehicles
output the **** information on the purport that on the magnetic sensor was
left, and the composition of the vehicle detection system which enabled it
to manage parking vehicles with the output of said car presence
information       and     ****      information      was     adopted.
[0017]According to such composition, the advantage of the vehicle
detecting device of this invention can be enjoyed, exact car presence
information and **** information can be outputted based on highly precise
and reliable vehicle detection, and it can use effective in management of
parking                               vehicles.
[0018]
[Mode for carrying out the invention]Hereafter, an embodiment of the
invention       is    described      with     reference       to    figures.
[0019][Embodiment of a vehicle detecting method] Drawing 1 - 3 explain
the embodiment of the vehicle detecting method by this invention first.
[0020]In this embodiment, as shown in drawing 1, to the ground surface
14 in the width which the vehicles (car) 10 pass, or underground. The
magnetic sensor 12 which has arranged two or more magnetism detecting
elements 11A, 11B, and 11C which have magnetic field detection
sensitivity in the direction (Z direction) vertical to a ground surface so that
it may stand in a line along with the longitudinal direction of the vehicles 10
is     installed,     and      vehicle     detection       is    performed.
[0021]The external magnetic field intensity change as on the basis of the
state where each magnetism detecting element of the magnetic sensor 12
detects external magnetic field intensity, and there are no vehicles 10 is
measured, and total of the absolute value of two or more measured
magnetic-field-strength change detects vehicles by the judgment of
whether       to    exceed      a     predetermined       joint   threshold.
[0022]This method was drawn from the following examining results.
[0023]First, on the ground surface 14 in the width which the vehicles 10
pass as shown in drawing 2, The magnetic sensor 12 which comprised
one magnetism detecting element which has magnetic field detection
sensitivity in the Z direction which is a vertical direction to the ground
surface 14 is arranged, the vehicles 10 were moved on the sensor 12, the
magnetic sensor 12 detected external magnetic field intensity, external
magnetic field intensity change was measured, and the situation of the
change was investigated. The variation of external magnetic field intensity
made the measurement value in the state where there are no vehicles 10
the initial value used as a standard, and displayed a changed part from it.
The element using the magnetic impedance component mentioned later as
a magnetic sensing device was used for the magnetism detecting element.
Two or more vehicles performed the sampling. Four data measuring of a
characteristic example is shown in drawing 2 (a) - (d) in it.
[0024]Generally, magnetic field distribution of the cross direction of a bar
magnet has a peak of reverse polarity at both ends of the bar magnet 16
like drawing 3, and has a tendency which carries out a zero cross in the
center section. On the other hand, it can guess that the body of a car
constitutes a roughly big bar magnet from a vehicles longitudinal direction
from it being in agreement with how of data measuring of drawing 2 to
lengthen the skirt near the both-ends peak of magnetic field distribution of
drawing 3 by (c) and (d), especially, if it observes near the both ends of a
magnetic field change. However, attitude of a peak has dispersion
considerably by overall magnetic-field-strength distribution, and it does
not become a beautiful form like a bar magnet because local
magnetization exists by part each of a body pars basilaris ossis occipitalis.


[0025]Since detection of vehicles will detect a magnetic field of a body
center section if detection of parking vehicles is taken into consideration,
for example, it observes a magnetic field of a center of the body by width
of the length of a half of the body shown in the range of H seal in a figure
of each data measuring of drawing 2. It is because movement speed of a
difference in the length of each body and the body at the time of
Measurement Division had dispersion that the length of H seal differs.
[0026]Also when unevenness is looked at by magnetic-field-strength
change within the limits of H seal of data of four examples and a zero
cross exists, an absolute value of a measurement value may go into a
DETTO point on which it is less than threshold s, and one magnetism
detecting element is not enough as it for vehicle detection at a certain
thing.
[0027]When threshold s of one magnetism detecting element considers
resolution of a magnetism detecting element, and S/N of a circuit, 0.05
gauss of a minimum is a limit, and considering that a maximum has about
0.1 gauss vehicles like drawing 2 (c) in the maximum of a magnetic field
change by vehicles, it is difficult to set up exceeding 0.1 gauss.
[0028]Then, two or more magnetism detecting elements are arranged
along with a vehicles longitudinal direction, and if vehicle detection is
carried out by whether either exceeds threshold s, detection probability will
increase.
[0029]However, in a case of vehicles of drawing 2 (d), when four
magnetism detecting elements have been arranged to each of a position
corresponding to four points, a in a figure, b, c, and d, a measurement
value by which element will also be less than 0.05 gauss. If such a case is
taken into consideration, a device which raises detection probability further
is                                required.
[0030]Then, an absolute value of a measurement value of two or more
magnetic-field-strength change which detected external magnetic field
intensity by each of two or more magnetism detecting elements, and was
measured is added, A value of a product which, on the other hand, hung
said number (addition numbers of a measurement value) n of a magnetism
detecting element of added square roots on threshold s at the time of
detection by an independent magnetism detecting element is set up as
joint threshold S, If vehicle detection is judged by whether total of an
added result of said absolute value exceeds joint threshold S, it is
detectable            by           high            probabilities.
[0031]A noise component serves as a mean square to addition of an
output of each magnetism detecting element, and if it is considered as a
noise component of the respectively same size, this will use that a product
of a noise for one element and a square root of the addition numbers n
serves as a noise at the time of combination, and will try to earn the whole
S/N.
[0032]For example, magnetic-field-strength change, a of the data
measuring of the vehicles of drawing 2 (d), b, c, and d, of four points, It
will be 0.03G-0.04G-0.02G-0.03G, and if threshold s of independent
detection is set to 0.05G, when these are added, it will be 0.12G, and
0.05xroot4=0.1 gauss is set to joint threshold S, total of the added result
of an output will exceed joint threshold S, and detection of it will be
attained.
[0033]Therefore, when the magnetic field component of a direction
vertical to the ground surface of the magnetic field generated from
vehicles is detected by two or more Magnetism detecting elementn and the
magnetic-field-strength change by vehicles existence is measured, It
turned out that it is suitable that the total adding each of the absolute value
of magnetic-field-strength change measured based on the detection result
of n magnetism detecting elements of a result performs vehicle detection
by whether joint threshold S as independent threshold sxrootn is exceeded.


[0034]By the way, since a magnetic-field-detection output may become
near a zero cross with a certain element and total of the above-mentioned
added result may become low when detecting as mentioned above by two
or more magnetism detecting elements, the method explained below can
also be chosen as a method of raising vehicle detection efficiency further.
[0035]Arrange in descending each absolute value of the measurement
value of the external magnetic field intensity change from the initial value
which detected external magnetic field intensity by two or more magnetism
detecting elements of the magnetic sensor mentioned above, and was
measured, consider it as |deltaH(k) | (k= 1, 2, ordinal number of --), and
Namely, this value, They are [ threshold s in the case of one magnetism
detecting element, and ] the following expression about said addition
numbers                               n.[0036]
[Mathematical                  formula                  2]




[0037]It compares whether it is alike, it sets, substitutes one by one from
k= 1, and the above-mentioned expression is satisfied, and when the
above-mentioned expression is satisfied, it judges with having detected
vehicles.
[0038]According to this method, vehicle detection efficiency can be raised
by adding the measurement value of two or more external magnetic field
intensity change to descending one by one, and using for the judgment of
vehicle                             detection.
[0039]In above-mentioned explanation, the "ground surface of
"underground" meaning the inside of those fields including all the fields
that vehicles, such as a floor line in the building of not only the ground
surface of the ground, and the road surface of a road and the ground
surface of an outdoor parking lot but a multi-level car parking tower, run
fields      thru/or       park"      of      14       is       natural.
[0040][Embodiment of a vehicle detecting device] Next, the embodiment
of a vehicle detecting device which enforces concretely the vehicle
detecting method mentioned above, and performs vehicle detection is
described.
[0041]First, the magnetism detecting element of the magnetic sensor used
for a vehicle detecting device is explained. Being required of this
magnetism detecting element should be 10 or more milligauss in (1)
magnetic            field          detection           sensitivity.
[0042](2) There is two or more dispersion [ little ] of the performance of
an                 element               for               use.
[0043](3) Considering ground surface installation, the height of an element
should               be            several            millimeters.
[0044](4) The detector circuit of an element is excellent in a noise-proof
and temperature characteristics, and be low power consumption.
[0045]Although there is a flux gate type magnetism detecting element as
what satisfies the conditions of (1), if it is going to raise detection
sensitivity with this element, several 10 mm of the length of an element will
be needed, and it will not be satisfied with it of the conditions of (3).
[0046]Since it is easy to come out of dispersion in performance, a
problem produces a flux gate type magnetism detecting element also on
condition                       of                   (2).
[0047]Then, the magnetism detecting element constituted using a
magnetic impedance component is seemed that it is the optimal by it.
[0048]The       magnetic    impedance      component      is   indicated by
JP,H7-181239,A and the element body as a magnetic body is constituted
from an amorphous wire or these days by the magnetic thin film etc. If the
high frequency current of an MHz band is impressed to this element body,
according to a magnetic impedance effect, according to an external
magnetic field, the impedance of an element body changes several 10%,
and can detect an external magnetic field using this.
[0049]Sensitivity of a magnetic impedance component has the sensitivity
of a 10-5 gauss stand, and number milligauss is securable and it is
satisfied also with practical resolution in a case where it connects with a
circuit of a magnetism detecting element of conditions of (1).
[0050]From there being little influence of a demagnetizing field, it is easy
for the length of an element to be 5 mm or less, and conditions of (3) are
also                                  cleared.
[0051]About dispersion in performance, when supplied with an amorphous
wire, since it is easy to control thickness, dispersion in performance
resulting from an outside dimension of a magnetic body of an element
body is pressed down, and is satisfied with that there is little dispersion in
a path of a wire, and a magnetic film of conditions of (2).
[0052]Although application was considered according to contents
reported at a society etc. about magnetic field detection which uses the
Colpitts oscillating circuit about conditions of (4), there is a problem
practically.
[0053]For example, an application of a magnetic field sensor as an
azimuth sensor is shown by an "amorphous wire MI Colpitts oscillation type
micro magnetic sensor" announced at the 18th Maganetics Society of
Japan         academic          lecture      meeting        (14pB-7).
[0054]In composition of this azimuth sensor, an amorphous wire is
included in a Colpitts type oscillator, and since change of an external
magnetic field turns into change of oscillation amplitude and it appears, an
output is obtained through a detector circuit. While sending a direct current
through a coil directly twisted around a wire of an element, applying a DC
bias magnetic field and making it operate in a field where sensitivity is
high, he is trying to know the polarity of the direction of north and south.
[0055]However, in minute magnetic field detection, such as
geomagnetism (about 0.3 gauss) by this method. Change of an output
after a detector circuit is as small as several percent, and in order to treat
absolute value change of oscillation amplitude as an output as it is,
sufficient S/N is not obtained from it being easy to be influenced by
change of power supply voltage, the temperature characteristics of an
element, etc. by amplitude fluctuation, and it is unreliable.
[0056]So, in this embodiment, circuitry of a magnetism detecting element
shown          in        drawing         4       was         adopted.
[0057]Circuitry of a magnetism detecting element shown in drawing 4
consists of a Colpitts oscillator, a detector circuit, and a comparator, the
magnetic impedance component 1 mentioned above is included in a
Colpitts oscillator, it direct-winds, or the magnetic impedance component
1 is approached, and the coil 2 for bias is formed.
[0058]In this composition, AC bias current Ib is sent through the coil 2,
and an about **1-**2 gauss AC bias magnetic field is impressed to the
magnetic impedance component 1. As shown in (a), amplitude modulation
of the oscillation output which appears like the after-mentioned by this at
an A point in a figure of a Colpitts oscillator according to intensity of the
external magnetic field Hex for [ which is impressed to the magnetic
impedance component 1 ] detection is carried out, A ripple waveform
corresponding to a bias magnetic field which has the difference of
elevation of an adjacent peak corresponding to intensity of the external
magnetic field Hex by detecting this in a detector circuit at a B point as
shown in (b) is acquired, By carrying out a party rate with the comparison
voltage Vref which crosses a voltage waveform of said ripple with a
comparator, a Pulse-Density-Modulation output corresponding to intensity
of the external magnetic field Hex can be obtained at C point.
[0059]A signal of AC bias current Ib carries out dividing of the clock from
a microcomputer judgment part mentioned later, with a low pass filter, it
may be made into a sine wave or the shape of a triangular wave, and it
may throw it in, or may provide and throw in an oscillator individually.
[0060]Next, details of operation of circuitry of a magnetism detecting
element     of   drawing     4  mentioned     above     are   explained.
[0061]the characteristic of a magnetic impedance component is
symmetrical with the direction of +- in several gauss to the external
magnetic field Hex, as shown in drawing 5 -- a V character-like
impedance change is shown in general. As shown in drawing 5 (a) as a
principle of operation of the magnetic impedance component 1 of drawing
4, when there is no external magnetic field, an AC bias magnetic field is +.
- It touches symmetrically, In change of impedance to it, an impedance
change which the difference of elevation does not have in peaks on a
ripple breaks out by a magnetic field twice the frequency of AC bias.
[0062]Since an AC bias magnetic field and an unsymmetrical magnetic
field which an external magnetic field superimposed will start the magnetic
impedance component 1 like drawing 5 (b) there if an external magnetic
field is impressed to a longitudinal direction of the magnetic impedance
component 1, An impedance change (ripple waveform) from which height
of a peak differs by turns on an impedance change arises.
[0063]The ripple waveform in an impedance change as showed the output
after detection of drawing 4 (b) which appeared as amplitude modulation
in the oscillation amplitude characteristic of the Colpitts oscillator as
change of this impedance was shown in drawing 4 (a), and detected that
oscillation output in the detector circuit by drawing 5 (b), and a similar
signal are acquired. The size of an external magnetic field is changed into
the output of a digital signal by which Pulse Density Modulation was
carried out by carrying out a party rate with the comparison voltage Vref
which crosses a ripple waveform as the signal is shown in drawing 6 in a
comparator. That is, the Pulse-Density-Modulation output in which the
pulse which is two kinds from which pulse width differs according to
external magnetic field intensity appears by turns is obtained.
[0064]Thus, pulse width [ of two kinds of pulses ] A which appears by
turns, and B can be measured and evaluated using the timer counter of a
microcomputer, and the digital data in which external magnetic field
intensity is shown can be obtained by asking for the digital data of
difference A-B of pulse width by an operation after that. Although the
measurement data of pulse width to a actual external magnetic field is
shown in drawing 7, in **0.5 gauss shows an almost linear change. The
numerical input value of joint threshold S mentioned above can be decided
by transposing the magnetic field strength of magnetism detecting element
independent threshold s to the math-processing value of pulse width
based on this data, and hanging the several n square root of a magnetism
detecting               element               on              it.
[0065]And the digital data of difference A-B of the pulse width measured
in the state where there are no vehicles, in detection of vehicles is
memorized as data of the initial value of the external magnetic field
intensity used as a standard, Then, the absolute value of the difference of
difference A-B of pulse width and the initial value according to the
measured external magnetic field intensity is calculated as data
corresponding to the absolute value of intensity change of an external
magnetic field, It can ask for total of the data of said absolute value called
for by further two or more magnetism detecting elements, and the
existence of vehicles can be judged by whether the figure exceeded the
numerical         value       of      joint       threshold       S.
[0066]Next, drawing 8 explains the composition of the vehicle detecting
device using the magnetism detecting element of drawing 4.
[0067]Colpitts oscillator 3 incorporating the magnetic impedance
component 1 which wound the coil 2 for bias which 12 is a magnetic
sensor and was mentioned above in the composition of the vehicle
detecting device shown in drawing 8, They are the marks 11A and 11B
about the magnetism detecting element of drawing 4 which consists of the
detector circuit 4 and the comparator 5. -- As shown in 11N, N pieces are
provided and it is constituted. Magnetism detecting elements 11A and 11B
-- 11N is arranged so that it may rank with the ground surface in the band
pass of vehicles, or underground along with the longitudinal direction of
vehicles as mentioned above, and each element can be giving magnetic
field detection sensitivity in the direction vertical to a ground surface.
[0068]18 is a microcomputer judgment part which comprises a
microcomputer, analyzes the Pulse-Density-Modulation output of each
magnetism detecting element of the magnetic sensor 12, and judges the
existence of vehicles. The microcomputer judgment part 18, Either the
timer counter 20 which counts pulse width [ of the control section 19
which performs whole control and various data processing, and the Pulse-
Density-Modulation output mentioned above ] A, and B or magnetism
detecting elements 11A-11N are chosen. It consists of the selector 21
which inputs the output pulse into the timer counter 20 and the clock
generator 22, the clock divider 23, the low pass filter 24, and the bias
circuit                    (amplifier)                 25.
[0069]Dividing is carried out so that the clock signal which the clock
generator 22 oscillates may become the range of 1 kHz - 100 kHz by the
clock divider 23 in this composition, The low pass filter 24 and the bias
circuit 25 let this signal by which dividing was carried out pass, the signal
of the AC bias current of a sine wave or the shape of a triangular wave is
formed, and it is impressed by the coil 2 for bias which are each
magnetism detecting elements 11A-11N of the magnetic sensor 12. The
feed zone of this bias current may be provided in the magnetic sensor 12
side.
[0070]Next, the vehicle detection operation by the composition of drawing
8 is explained. First, the initial value of the external magnetic field intensity
used as the standard for asking for external magnetic field intensity change
in the state where there are no vehicles is measured. For this reason, with
the magnetic sensor 12, the pulse signal which detected external magnetic
field intensity by two or more magnetism detecting elements 11A-11N, and
carried out Pulse Density Modulation is outputted as mentioned above, and
it sends to the selector 21 of the microcomputer judgment part 18.
[0071]With the command from the control section 19, the selector 21
chooses and sends two kinds of pulses A and B further mentioned above
while it chooses the output pulse signal of two or more magnetism
detecting elements 11A-11N which should be sent to the timer counter 20
one            by         one            and          sends          it.
[0072]In the timer counter 20, the pulse width of two kinds of said pulses
A and B of two or more magnetism detecting elements sent one by one is
counted and evaluated, and the data is sent to the control section 19.
[0073]In the control section 19, difference A-B of the pulse width data of
A pulse and B pulse evaluated with the timer counter 20 is computed for
every magnetism detecting element, and the measured value of external
magnetic field intensity is calculated. The measured data is recorded on
memory storage, such as RAM26 in the control section 19, as initial value
data           used             as           a           standard.
[0074]Then, in order to detect vehicles, the detection and the
Measurement Division of external magnetic field intensity by each
magnetism detecting element are performed in the same procedure as the
above, In the control section 19, it asks separately, absolute-value-izes by
using the difference of said measurement data and initial value data as
external magnetic field intensity change data, and asks for the total, and
the existence of vehicles is judged by whether it is over predetermined joint
threshold S which the total mentioned above. And in the case of the
vehicle detection system mentioned later, car presence information etc.
are taken out based on the result of said judgment.
[0075]In order not to treat the amplitude of a Colpitts oscillator as an
absolute value in the circuitry of the magnetism detecting element of
drawing 4 as an advantage of the equipment of these above embodiments
probably but to treat a changed part of amplitude, a low change of the
frequency by change, temperature characteristics, etc. of power supply
voltage            can             be               disregarded.
[0076]Since the detect output of the external magnetic field intensity in the
magnetic sensor 12 is digitized-output-ized by the Pulse Density
Modulation by a comparator, The magnetic sensor 12 and the
microcomputer judgment part 18 connect two or more magnetic sensors
12 to the microcomputer judgment part 18, and can carry out common use
of the microcomputer judgment part 18 to two or more magnetic sensors
12 while also being able to perform installation to isolate and obtaining the
flexibility               of                   installation.
[0077]Since the whole equipment which constituted the magnetism
detecting element very small, could constitute the magnetic sensor 12
small, and includes the microcomputer judgment part 18 can be made
small, The burden of installation cost is small, and it is low power
consumption, and since the prolonged energization use which was poor at
conventional loop coil type equipment is possible, the use of vehicle
detection                   is                  expandable.
[0078][An embodiment of a vehicle detection system] Next, drawing 9
and drawing 10 explain an embodiment of a vehicle detection system for
parking-vehicles management in a motor pool using a vehicle detecting
device of drawing 8 mentioned above. As for this vehicle detection system,
it is needless to say that a portion of the magnetic sensor 12 is provided in
a ground surface of a motor pool or underground at least, and it carries
out     of    a    vehicle     detecting    device    of    drawing    8.
[0079]Drawing 9 is a block diagram showing functional composition of a
vehicle detection system of this embodiment. Composition of those other
than magnetic sensor 12 is specifically realized in drawing 9 by hardware
and software of the microcomputer judgment part 18 of drawing 8.
[0080]In drawing 9, it realizes from the control section 19 of drawing 8,
the timer counter 20, and the selector 21, and the measurement means 27
measures external magnetic field intensity change as on the basis of the
state where there are no vehicles based on a detection result of external
magnetic field intensity by the magnetism detecting elements 11A-11N of
the magnetic sensor 12 as mentioned above. This measurement means 27
has the initial value memory measure 28 which memorizes a value of
external magnetic field intensity detected by the magnetism detecting
elements 11A-11N in the state where there are no vehicles as an initial
value used as a standard, and measures external magnetic field intensity
change on the basis of an initial value memorized to this memory measure
28. The memory measure 28 is specifically constituted as RAM26 of
drawing                                  8.
[0081]It realizes as a function of the control section 19, and the vehicle
detection judging means 29 judges vehicle detection as mentioned above
based on the measuring result of the measurement means 27.
[0082]Penetration, a stop, and the **** judging means 30 are realized as
a function of processing of Step S3 of below-mentioned drawing 10 by the
control section 19, S6, and S9, Based on the decided result of the vehicle
detection by the vehicle detection judging means 29. [ whether vehicles
advanced into the motor pool, and ] It is judged whether on whether it
advanced on the magnetic sensor 12 formed in the motor pool, whether
whether whether it having stopped in the motor pool and a motor pool
having been left and vehicles stopped on the magnetic sensor 12, and the
magnetic           sensor           12          was            left.
[0083]Car presence and the **** information output means 31 are realized
as a function of Step S7 of drawing 10 by the control section 19, and
processing of S10, Based on the decided result of penetration, a stop, and
the **** judging means 30, vehicles have stopped at the motor pool, the
car presence information on the purport that vehicles have stopped on the
magnetic sensor 12, and vehicles left the motor pool, namely, vehicles
output the **** information on the purport that on the magnetic sensor 12
was                                    left.
[0084]External magnetic field intensity is detected by the basis of such
composition by the magnetism detecting elements 11A-11N of the
magnetic sensor 12, The external magnetic field intensity change on the
basis of the state where there are no vehicles by the measurement means
27 based on the detection result is measured, and the judgment of vehicle
detection is performed by the vehicle detection judging means 29 based
on the measuring result. And based on the decided result of vehicle
detection, penetration of the vehicles in a motor pool, a stop, and **** are
judged by the judging means 30, and car presence information thru/or ****
information are outputted by the output means 31 based on the decided
result.
[0085]Next, drawing 10 explains the details of vehicle detection operation
of this system. Drawing 10 is a flow chart which shows the procedure of
the vehicle detection processing by the control section 19 of drawing 8
which realizes each means 27, 29, 30, and 31 of drawing 9.
[0086]On vehicle detection processing and first in Step S1 of drawing 10
the control section 19, External magnetic field intensity by each magnetism
detecting element of the magnetic sensor 12 is made to detect as
mentioned above in the state where there are no vehicles, It asks for
measurement data of external magnetic field intensity of A-B mentioned
above based on the detection result, this is set up as initial value data
used as a standard which asks for external magnetic field intensity change,
and it memorizes to recording equipment of RAM26 grade. Since there are
no vehicles into a motor pool at this time, the control section 19 checks
****                              information.
[0087]Next, in order to judge penetration of vehicles to the magnetic
sensor 12 top formed in penetration of vehicles into a motor pool, i.e., a
ground surface of a motor pool, and underground, Detection and
Measurement Division of external magnetic field intensity from vehicles by
each magnetism detecting element are performed in a procedure
mentioned above (Step S2), It judges with vehicles having advanced into a
motor pool, when it absolute-value-ized in quest of a difference of each
measurement data A-B and initial value data separately and the total was
over predetermined joint threshold S, and when not having progressed and
exceeded for the following procedure, it returns to Step S2 (Step S3).
[0088]When vehicles enter in a motor pool even in a front procedure, can
judge that, but. Since it thinks when passing without stopping then, after
judging penetration of vehicles at Step S3, detection and Measurement
Division of the external magnetic field intensity from the vehicles by each
magnetism detecting element are performed again (step S4), and it
compares with total of the absolute value of data A-B measured last time
(Step S5). When this measurement value is changing from the last
measurement value, it judges with vehicles moving in the inside of a motor
pool,          and         returns          to       step        S4.
[0089]Since it will be either when vehicles stop in a motor pool or a
passing car comes out out of a motor pool as it is if change of measured
value is lost, In order to carry out that judgment which is the any, in quest
of the difference of an initial value and measured-value-data A-B, it
absolute-value-izes separately by all the magnetism detecting elements, It
judges that the total is in the car presence state which vehicles have
stopped in a motor pool when total exceeds joint threshold S as compared
with the above-mentioned predetermined joint threshold S (that is, it has
stopped on the magnetic sensor 12) (Step S6), and car presence
information is taken out (Step S7). On the other hand, when total of the
absolute value of aforementioned difference A-B is not over joint threshold
S, it judges with the passing car having come out out of the motor pool as
it        is,       and       returns      to       Step        S2.
[0090]Next, detection of the magnetic field of the vehicles by each
magnetism detecting element in order to detect **** of the parked
vehicles, Measure (Step S8) and it absolute-value-izes in quest of the
difference of measurement data A-B and the data of an initial value
separately, When the total is over predetermined joint threshold S, vehicles
are judged continuously to be under parking, It returns to Step S8, and
when it repeated and is not over measurement, vehicles judge with having
left the inside of a motor pool (that is, on the magnetic sensor 12 was left),
take out **** information (Step S10), return to Step S2, and are again
repeated       from     detection    of     penetration    of   vehicles.
[0091]Thus, based on the detection result of the magnetic field from
vehicles, a stop and **** can be judged during penetration of the vehicles
in a motor pool, and movement, and car presence information and ****
information can be outputted. And the advantage of the vehicle detecting
device of this invention can be enjoyed, a stop and **** can be correctly
judged during penetration of vehicles, and movement by highly precise and
reliable vehicle detection, and exact car presence information and ****
information can be outputted. Therefore, the vehicle detection system of
this embodiment is effectively [ as management of parking vehicles /
because of management of parking duration, the empty area display in a
scale      parking    lot,   vehicle     guiding,    etc.   ]   available.
[0092]
[Effect of the Invention]According to the vehicle detecting method of this
invention, so that clearly from the above explanation to the ground surface
in the band pass of vehicles, or underground. The magnetic sensor which
put in order two or more magnetism detecting elements which have
magnetic field detection sensitivity in the direction vertical to a ground
surface along with the vehicles longitudinal direction is installed, The
external magnetic field intensity change as on the basis of the state where
each of a magnetism detecting element detects external magnetic field
intensity, and there are no vehicles is measured, Since total of the absolute
value of two or more measurement values of this measuring result was
made to detect vehicles by the judgment of whether to exceed
predetermined joint threshold S, The influence of the zero crossing point
which the magnetic field polarity looked at by distribution of the magnetic
field strength in the case of measuring the magnetic field generated from a
vehicles pars basilaris ossis occipitalis reverses can be avoided, and highly
precise and reliable vehicle detection can be performed.
[0093]While being able to perform reliable vehicle detection with high
degree of accuracy with the vehicle detecting method of this invention
according to the vehicle detecting device of this invention, a magnetic
sensor, For example, it can constitute from small size which consists of
plurality of the small magnetism detecting element constituted using the
magnetic impedance component as a magnetic sensor of low power
consumption, Compared with the equipment using the conventional loop
coil type sensor, prolonged continuous use is possible, installation can
also be easily performed by low cost, and the use of vehicle detection can
be                                expanded.
[0094]According to the vehicle detection system using the vehicle
detecting device of this invention. By vehicle detection enjoy the
advantage of the vehicle detecting device of this invention, highly precise
and reliable, exact car presence information, **** information can be
outputted and the outstanding effect of being available is acquired
effectively [ because of management of parking duration, the empty area
display in a scale parking lot, vehicle guiding, etc. ] as management of
parking vehicles.


TECHNICAL FIELD


[Field of the Invention]This invention detects the magnetic field generated
from vehicles, such as a car, with a magnetic sensor, and detects vehicles
magnetically, namely, relates to the vehicle detecting method which
detects the existence of vehicles thru/or passage, a vehicle detecting
device, and a vehicle detection system.


PRIOR ART


[Description of the Prior Art]Conventionally, the sensor which detects
vehicles, such as a car, is used in the use of measuring the distinction of
the existence of parking in the managerial system of a motor pool, and the
traffic   of    the     vehicles    in  a    traffic   control   system.
[0003]Usually, since vehicles, such as a car, are tinged with magnetism
using the metallic material which is easy to be tinged with magnetism, such
as a steel plate, it is detecting the magnetic field generated from vehicles
with a magnetic sensor, and it is possible to recognize existence of
vehicles                     or                  passage.
[0004]Conventionally, in the motor pool, the loop coil type magnetic
sensor was buried in the earth, and it has been used for vehicle detection
in it. A loop coil type magnetic sensor is that generate a magnetic field by
an eddy current in the metal part of the body of vehicles to the alternating
current sent through a coil, or the magnetic field from the body's own
magnetization interlinks with a loop coil, A coil's own inductance changes,
it is changed as change of oscillating frequency or amplitude in a circuit,
and vehicle detection is performed by the existence of the change.
[0005]However, although the loop coil type magnetic sensor is spreading
by detection of vehicles, it has the following problems.
[0006]- Since a loop coil opens an interval a little with vehicles and is
installed, in order to detect the inductance variation in vehicles existence,
there is the necessity of enlarging size of a sensitivity secured upper coil
(about                                1mx1m).
[0007]- If metal bodies, such as a steel rod, are in the neighborhood, S/N
cannot                be             taken              enough.
[0008]- Since a loop coil is large and power consumption is large, it is not
fit         for         continuous         energization         use.
[0009]- A coil is a size which is about 1mx1m, and the burden of
construction expense is heavy in subterranean installation.
[0010]Then, although the small magnetic sensor was used and the
substitution was considered, When the magnetic field generated from a
vehicles pars basilaris ossis occipitalis was measured, near the zero
crossing point which remarkable unevenness is made to distribution of
magnetic field strength, and magnetic field polarity reverses by the local
magnetization of Body Manufacturing Division article each which it has, it
turned out that the dead point which does not exceed a threshold required
for the judgment of vehicle detection arises.


EFFECT OF THE INVENTION


[Effect of the Invention]According to the vehicle detecting method of this
invention, so that clearly from the above explanation to the ground surface
in the band pass of vehicles, or underground. The magnetic sensor which
put in order two or more magnetism detecting elements which have
magnetic field detection sensitivity in the direction vertical to a ground
surface along with the vehicles longitudinal direction is installed, The
external magnetic field intensity change as on the basis of the state where
each of a magnetism detecting element detects external magnetic field
intensity, and there are no vehicles is measured, Since total of the absolute
value of two or more measurement values of this measuring result was
made to detect vehicles by the judgment of whether to exceed
predetermined joint threshold S, The influence of the zero crossing point
which the magnetic field polarity looked at by distribution of the magnetic
field strength in the case of measuring the magnetic field generated from a
vehicles pars basilaris ossis occipitalis reverses can be avoided, and highly
precise and reliable vehicle detection can be performed.
[0093]While being able to perform reliable vehicle detection with high
degree of accuracy with the vehicle detecting method of this invention
according to the vehicle detecting device of this invention, a magnetic
sensor, For example, it can constitute from small size which consists of
plurality of the small magnetism detecting element constituted using the
magnetic impedance component as a magnetic sensor of low power
consumption, Compared with the equipment using the conventional loop
coil type sensor, prolonged continuous use is possible, installation can
also be easily performed by low cost, and the use of vehicle detection can
be                                 expanded.
[0094]According to the vehicle detection system using the vehicle
detecting device of this invention. By vehicle detection enjoy the
advantage of the vehicle detecting device of this invention, highly precise
and reliable, exact car presence information, **** information can be
outputted and the outstanding effect of being available is acquired
effectively [ because of management of parking duration, the empty area
display in a scale parking lot, vehicle guiding, etc. ] as management of
parking vehicles.


TECHNICAL PROBLEM


[Problem to be solved by the invention]Then, a reliable vehicle detecting
method in which SUBJECT of this invention can perform magnetic
detection of vehicles with high precision using a magnetic sensor which
consists of two or more small magnetism detecting elements, And it is in
providing a vehicle detection system which is a vehicle detecting device
which performs vehicle detection by the method, can attain a
miniaturization and can be used effective in management of parking
vehicles using a vehicle detecting device of low power consumption, and
this vehicle detecting device.


MEANS


[Means for solving problem]In a vehicle detecting method which according
to this invention detects a magnetic field generated from vehicles with a
magnetic sensor, and detects vehicles magnetically in order to solve
above-mentioned SUBJECT, A magnetic sensor which put in order two or
more magnetism detecting elements which have magnetic field detection
sensitivity in the direction vertical to a ground surface along with a vehicles
longitudinal direction is installed in a ground surface in a band pass of
vehicles, or underground, External magnetic field intensity change as on
the basis of the state where each of two or more of said magnetism
detecting elements detects external magnetic field intensity, and there are
no vehicles was measured, and a method of detecting vehicles by the
judgment of whether total of an absolute value of two or more
measurement values of this measuring result exceeds predetermined joint
threshold                S               was             adopted.
[0013]According to such a vehicle detecting method, influence of a zero
crossing point which magnetic field polarity looked at by distribution of
magnetic field strength in a case of measuring a magnetic field generated
from a vehicles pars basilaris ossis occipitalis reverses can be avoided,
and highly precise and reliable vehicle detection can be performed.
[0014]According to this invention, it is a vehicle detecting device which
detects a magnetic field generated from vehicles with a magnetic sensor,
and detects vehicles magnetically, A magnetic sensor which consists of
two or more magnetism detecting elements arranged so that it may have
magnetic field detection sensitivity in the direction vertical to a ground
surface and may rank with a ground surface in a band pass of vehicles, or
underground along with a vehicles longitudinal direction, A measurement
means which measures each of external magnetic field intensity change as
on the basis of the state where there are no vehicles to each magnetism
detecting element, based on external magnetic field intensity detected by
each of two or more of said magnetism detecting elements, Total of each
absolute value of a measurement value of external magnetic field intensity
change measured by this measurement means adopted composition of a
vehicle detecting device which has a judging means which judges vehicle
detection by whether predetermined joint threshold S is exceeded.
[0015]While being able to perform reliable vehicle detection with high
degree of accuracy with a vehicle detecting method of this invention
according to such composition, the magnetic sensor can consist of small
size which consists of plurality of a small magnetism detecting element
constituted, for example using a magnetic impedance component as a
magnetic       sensor     of       low     power      consumption.
[0016]It is a vehicle detection system which performs vehicle detection
using a vehicle detecting device by above-mentioned this invention
according to this invention, A judging means which judges whether
whether vehicles advanced on a magnetic sensor, whether it stopped on a
magnetic sensor based on a decided result of vehicle detection by a
judging means of said vehicle detecting device, and on a magnetic sensor
were left, Car presence information on a purport that vehicles have
stopped on a magnetic sensor based on a decided result of this judging
means, And it has an output means to which vehicles output ****
information on a purport that on a magnetic sensor was left, and
composition of a vehicle detection system which enabled it to manage
parking vehicles with the output of said car presence information and ****
information                  was                  adopted.
[0017]According to such composition, an advantage of a vehicle
detecting device of this invention can be enjoyed, exact car presence
information and **** information can be outputted based on highly precise
and reliable vehicle detection, and it can use effective in management of
parking                              vehicles.
[0018]
[Mode for carrying out the invention]Hereafter, an embodiment of the
invention     is    described     with     reference     to    figures.
[0019][Embodiment of a vehicle detecting method] Drawing 1 - 3 explain
the embodiment of the vehicle detecting method by this invention first.
[0020]In this embodiment, as shown in drawing 1, to the ground surface
14 in the width which the vehicles (car) 10 pass, or underground. The
magnetic sensor 12 which has arranged two or more magnetism detecting
elements 11A, 11B, and 11C which have magnetic field detection
sensitivity in the direction (Z direction) vertical to a ground surface so that
it may stand in a line along with the longitudinal direction of the vehicles 10
is     installed,     and      vehicle     detection       is   performed.
[0021]The external magnetic field intensity change as on the basis of the
state where each magnetism detecting element of the magnetic sensor 12
detects external magnetic field intensity, and there are no vehicles 10 is
measured, and total of the absolute value of two or more measured
magnetic-field-strength change detects vehicles by the judgment of
whether       to    exceed      a     predetermined       joint  threshold.
[0022]This method was drawn from the following examining results.
[0023]First, on the ground surface 14 in the width which the vehicles 10
pass as shown in drawing 2, The magnetic sensor 12 which comprised
one magnetism detecting element which has magnetic field detection
sensitivity in the Z direction which is a vertical direction to the ground
surface 14 is arranged, the vehicles 10 were moved on the sensor 12, the
magnetic sensor 12 detected external magnetic field intensity, external
magnetic field intensity change was measured, and the situation of the
change was investigated. The variation of external magnetic field intensity
made the measurement value in the state where there are no vehicles 10
the initial value used as a standard, and displayed a changed part from it.
The element using the magnetic impedance component mentioned later as
a magnetic sensing device was used for the magnetism detecting element.
Two or more vehicles performed the sampling. Four data measuring of a
characteristic example is shown in drawing 2 (a) - (d) in it.
[0024]Generally, magnetic field distribution of the cross direction of a bar
magnet has a peak of reverse polarity at both ends of the bar magnet 16
like drawing 3, and has a tendency which carries out a zero cross in the
center section. On the other hand, it can guess that the body of a car
constitutes a roughly big bar magnet from a vehicles longitudinal direction
from it being in agreement with how of data measuring of drawing 2 to
lengthen the skirt near the both-ends peak of magnetic field distribution of
drawing 3 by (c) and (d), especially, if it observes near the both ends of a
magnetic field change. However, attitude of a peak has dispersion
considerably by overall magnetic-field-strength distribution, and it does
not become a beautiful form like a bar magnet because local
magnetization exists by part each of a body pars basilaris ossis occipitalis.


[0025]Since detection of vehicles will detect the magnetic field of a body
center section if detection of parking vehicles is taken into consideration,
for example, it observes the magnetic field of the center of the body by the
width of the length of the half of the body shown in the range of H seal in
a figure of each data measuring of drawing 2. It is because the movement
speed of the difference in the length of each body and the body at the
time of Measurement Division had dispersion that the length of H seal
differs.
[0026]Also when unevenness is looked at by magnetic-field-strength
change within the limits of H seal of the data of four examples and a zero
cross exists, the absolute value of a measurement value may go into the
DETTO point on which it is less than threshold s, and one magnetism
detecting element is not enough as it for vehicle detection at a certain
thing.
[0027]When threshold s of one magnetism detecting element considers
the resolution of a magnetism detecting element, and S/N of a circuit, 0.05
gauss of a minimum is a limit, and considering that a maximum has about
0.1 gauss vehicles like drawing 2 (c) in the maximum of the magnetic field
change by vehicles, it is difficult to set up exceeding 0.1 gauss.
[0028]Then, two or more magnetism detecting elements are arranged
along with a vehicles longitudinal direction, and if vehicle detection is
carried out by whether either exceeds threshold s, detection probability will
increase.
[0029]However, in the case of the vehicles of drawing 2 (d), when four
magnetism detecting elements have been arranged to each of the position
corresponding to four points, a in a figure, b, c, and d, the measurement
value by which element will also be less than 0.05 gauss. If such a case is
taken into consideration, the device which raises detection probability
further                   is                   required.
[0030]Then, the absolute value of the measurement value of two or more
magnetic-field-strength change which detected external magnetic field
intensity by each of two or more magnetism detecting elements, and was
measured is added, The value of the product which, on the other hand,
hung said number (addition numbers of a measurement value) n of a
magnetism detecting element of added square roots on threshold s at the
time of detection by an independent magnetism detecting element is set
up as joint threshold S, If vehicle detection is judged by whether total of
the added result of said absolute value exceeds joint threshold S, it is
detectable            by            high            probabilities.
[0031]A noise component serves as a mean square to addition of the
output of each magnetism detecting element, and if it is considered as the
noise component of the respectively same size, this will use that the
product of the noise for one element and the square root of the addition
numbers n serves as a noise at the time of combination, and will try to
earn               the               whole               S/N.
[0032]For example, magnetic-field-strength change, a of the data
measuring of the vehicles of drawing 2 (d), b, c, and d, of four points, It
will be 0.03G-0.04G-0.02G-0.03G, and if threshold s of independent
detection is set to 0.05G, when these are added, it will be 0.12G, and
0.05xroot4=0.1 gauss is set to joint threshold S, total of the added result
of an output will exceed joint threshold S, and detection of it will be
attained.
[0033]Therefore, when the magnetic field component of a direction
vertical to the ground surface of the magnetic field generated from
vehicles is detected by two or more Magnetism detecting elementn and the
magnetic-field-strength change by vehicles existence is measured, It
turned out that it is suitable that the total adding each of the absolute value
of magnetic-field-strength change measured based on the detection result
of n magnetism detecting elements of a result performs vehicle detection
by whether joint threshold S as independent threshold sxrootn is exceeded.


[0034]By the way, since a magnetic-field-detection output may become
near a zero cross with a certain element and total of the above-mentioned
added result may become low when detecting as mentioned above by two
or more magnetism detecting elements, the method explained below can
also be chosen as a method of raising vehicle detection efficiency further.
[0035]Arrange in descending each absolute value of the measurement
value of the external magnetic field intensity change from the initial value
which detected external magnetic field intensity by two or more magnetism
detecting elements of the magnetic sensor mentioned above, and was
measured, consider it as |deltaH(k) | (k= 1, 2, ordinal number of --), and
Namely, this value, They are [ threshold s in the case of one magnetism
detecting element, and ] the following expression about said addition
numbers                              n.[0036]
[Mathematical                  formula                  2]




[0037]It compares whether it is alike, it sets, substitutes one by one from
k= 1, and the above-mentioned expression is satisfied, and when the
above-mentioned expression is satisfied, it judges with having detected
vehicles.
[0038]According to this method, vehicle detection efficiency can be raised
by adding the measurement value of two or more external magnetic field
intensity change to descending one by one, and using for the judgment of
vehicle                             detection.
[0039]In above-mentioned explanation, the "ground surface of
"underground" meaning the inside of those fields including all the fields
that vehicles, such as a floor line in the building of not only the ground
surface of the ground, and the road surface of a road and the ground
surface of an outdoor parking lot but a multi-level car parking tower, run
fields      thru/or       park"    of       14        is       natural.
[0040][Embodiment of a vehicle detecting device] Next, the embodiment
of a vehicle detecting device which enforces concretely the vehicle
detecting method mentioned above, and performs vehicle detection is
described.
[0041]First, the magnetism detecting element of the magnetic sensor used
for a vehicle detecting device is explained. Being required of this
magnetism detecting element should be 10 or more milligauss in (1)
magnetic            field         detection            sensitivity.
[0042](2) There is two or more dispersion [ little ] of the performance of
an               element              for                use.
[0043](3) Considering ground surface installation, the height of an element
should               be            several              millimeters.
[0044](4) The detector circuit of an element is excellent in a noise-proof
and temperature characteristics, and be low power consumption.
[0045]Although there is a flux gate type magnetism detecting element as
what satisfies the conditions of (1), if it is going to raise detection
sensitivity with this element, several 10 mm of the length of an element will
be needed, and it will not be satisfied with it of the conditions of (3).
[0046]Since it is easy to come out of dispersion in performance, a
problem produces a flux gate type magnetism detecting element also on
condition                       of                     (2).
[0047]Then, the magnetism detecting element constituted using a
magnetic impedance component is seemed that it is the optimal by it.
[0048]The       magnetic    impedance      component        is   indicated by
JP,H7-181239,A and the element body as a magnetic body is constituted
from an amorphous wire or these days by the magnetic thin film etc. If the
high frequency current of an MHz band is impressed to this element body,
according to a magnetic impedance effect, according to an external
magnetic field, the impedance of an element body changes several 10%,
and can detect an external magnetic field using this.
[0049]The sensitivity of a magnetic impedance component has the
sensitivity of a 10-5 gauss stand, and number milligauss is securable and it
is satisfied also with the practical resolution in the case where it connects
with the circuit of a magnetism detecting element of the conditions of (1).
[0050]From there being little influence of a demagnetizing field, it is easy
for the length of an element to be 5 mm or less, and the conditions of (3)
are                     also                      cleared.
[0051]About dispersion in performance, when supplied with an amorphous
wire, since it is easy to control thickness, dispersion in the performance
resulting from the outside dimension of the magnetic body of an element
body is pressed down, and is satisfied with that there is little dispersion in
the path of a wire, and a magnetic film of the conditions of (2).
[0052]Although application was considered according to the contents
reported at the society etc. about the magnetic field detection which uses
the Colpitts oscillating circuit about the conditions of (4), there is a
problem                              practically.
[0053]For example, the application of the magnetic field sensor as an
azimuth sensor is shown by the "amorphous wire MI Colpitts oscillation
type micro magnetic sensor" announced at the 18th Maganetics Society of
Japan         academic         lecture         meeting        (14pB-7).
[0054]In the composition of this azimuth sensor, an amorphous wire is
included in a Colpitts type oscillator, and since change of an external
magnetic field turns into change of oscillation amplitude and it appears, an
output is obtained through a detector circuit. While sending a direct current
through the coil directly twisted around the wire of the element, applying a
DC bias magnetic field and making it operate in the field where sensitivity
is high, he is trying to know the polarity of the direction of north and south.


[0055]However, in minute magnetic field detection, such as
geomagnetism (about 0.3 gauss) by this method. Change of the output
after a detector circuit is as small as several percent, and in order to treat
absolute value change of oscillation amplitude as an output as it is,
sufficient S/N is not obtained from it being easy to be influenced by
change of power supply voltage, the temperature characteristics of an
element, etc. by amplitude fluctuation, and it is unreliable.
[0056]So, in this embodiment, the circuitry of the magnetism detecting
element      shown         in     drawing       4      was      adopted.
[0057]The circuitry of the magnetism detecting element shown in drawing
4 consists of a Colpitts oscillator, a detector circuit, and a comparator, the
magnetic impedance component 1 mentioned above is included in the
Colpitts oscillator, it direct-winds, or the magnetic impedance component
1 is approached, and the coil 2 for bias is formed.
[0058]In this composition, AC bias current Ib is sent through the coil 2,
and an about **1-**2 gauss AC bias magnetic field is impressed to the
magnetic impedance component 1. As shown in (a), amplitude modulation
of the oscillation output which appears like the after-mentioned by this at
the A point in a figure of a Colpitts oscillator according to the intensity of
the external magnetic field Hex for [ which is impressed to the magnetic
impedance component 1 ] detection is carried out, The ripple waveform
corresponding to the bias magnetic field which has the difference of
elevation of the adjacent peak corresponding to the intensity of the
external magnetic field Hex by detecting this in a detector circuit at a B
point as shown in (b) is acquired, By carrying out a party rate with the
comparison voltage Vref which crosses the voltage waveform of said ripple
with a comparator, the Pulse-Density-Modulation output corresponding to
the intensity of the external magnetic field Hex can be obtained at C point.
[0059]The signal of AC bias current Ib carries out dividing of the clock
from the microcomputer judgment part mentioned later, with a low pass
filter, it may be made into a sine wave or the shape of a triangular wave,
and it may throw it in, or may provide and throw in an oscillator
individually.
[0060]Next, the details of operation of the circuitry of the magnetism
detecting element of drawing 4 mentioned above are explained.
[0061]the characteristic of a magnetic impedance component is
symmetrical with the direction of +- in several gauss to the external
magnetic field Hex, as shown in drawing 5 -- a V character-like
impedance change is shown in general. As shown in drawing 5 (a) as a
principle of operation of the magnetic impedance component 1 of drawing
4, when there is no external magnetic field, an AC bias magnetic field is +.
- It touches symmetrically, In change of impedance to it, an impedance
change which the difference of elevation does not have in peaks on a
ripple breaks out by a magnetic field twice the frequency of AC bias.
[0062]Since an AC bias magnetic field and the unsymmetrical magnetic
field which the external magnetic field superimposed will start the magnetic
impedance component 1 like drawing 5 (b) there if an external magnetic
field is impressed to the longitudinal direction of the magnetic impedance
component 1, The impedance change (ripple waveform) from which the
height of a peak differs by turns on an impedance change arises.
[0063]The ripple waveform in an impedance change as showed the output
after detection of drawing 4 (b) which appeared as amplitude modulation
in the oscillation amplitude characteristic of the Colpitts oscillator as
change of this impedance was shown in drawing 4 (a), and detected that
oscillation output in the detector circuit by drawing 5 (b), and a similar
signal are acquired. The size of an external magnetic field is changed into
the output of a digital signal by which Pulse Density Modulation was
carried out by carrying out a party rate with the comparison voltage Vref
which crosses a ripple waveform as the signal is shown in drawing 6 in a
comparator. That is, the Pulse-Density-Modulation output in which the
pulse which is two kinds from which pulse width differs according to
external magnetic field intensity appears by turns is obtained.
[0064]Thus, pulse width [ of two kinds of pulses ] A which appears by
turns, and B can be measured and evaluated using the timer counter of a
microcomputer, and the digital data in which external magnetic field
intensity is shown can be obtained by asking for the digital data of
difference A-B of pulse width by an operation after that. Although the
measurement data of pulse width to a actual external magnetic field is
shown in drawing 7, in **0.5 gauss shows an almost linear change. The
numerical input value of joint threshold S mentioned above can be decided
by transposing the magnetic field strength of magnetism detecting element
independent threshold s to the math-processing value of pulse width
based on this data, and hanging the several n square root of a magnetism
detecting               element               on              it.
[0065]And the digital data of difference A-B of the pulse width measured
in the state where there are no vehicles, in detection of vehicles is
memorized as data of the initial value of the external magnetic field
intensity used as a standard, Then, the absolute value of the difference of
difference A-B of pulse width and the initial value according to the
measured external magnetic field intensity is calculated as data
corresponding to the absolute value of intensity change of an external
magnetic field, It can ask for total of the data of said absolute value called
for by further two or more magnetism detecting elements, and the
existence of vehicles can be judged by whether the figure exceeded the
numerical         value       of      joint       threshold       S.
[0066]Next, drawing 8 explains the composition of the vehicle detecting
device using the magnetism detecting element of drawing 4.
[0067]Colpitts oscillator 3 incorporating the magnetic impedance
component 1 which wound the coil 2 for bias which 12 is a magnetic
sensor and was mentioned above in the composition of the vehicle
detecting device shown in drawing 8, They are the marks 11A and 11B
about the magnetism detecting element of drawing 4 which consists of the
detector circuit 4 and the comparator 5. -- As shown in 11N, N pieces are
provided and it is constituted. Magnetism detecting elements 11A and 11B
-- 11N is arranged so that it may rank with the ground surface in the band
pass of vehicles, or underground along with the longitudinal direction of
vehicles as mentioned above, and each element can be giving magnetic
field detection sensitivity in the direction vertical to a ground surface.
[0068]18 is a microcomputer judgment part which comprises a
microcomputer, analyzes a Pulse-Density-Modulation output of each
magnetism detecting element of the magnetic sensor 12, and judges
existence of vehicles. The microcomputer judgment part 18, Either the
timer counter 20 which counts pulse width [ of the control section 19
which performs whole control and various data processing, and a Pulse-
Density-Modulation output mentioned above ] A, and B or magnetism
detecting elements 11A-11N are chosen. It consists of the selector 21
which inputs the output pulse into the timer counter 20 and the clock
generator 22, the clock divider 23, the low pass filter 24, and the bias
circuit                    (amplifier)                  25.
[0069]Dividing is carried out so that a clock signal which the clock
generator 22 oscillates may become the range of 1 kHz - 100 kHz by the
clock divider 23 in this composition, The low pass filter 24 and the bias
circuit 25 let this signal by which dividing was carried out pass, a signal of
AC bias current of a sine wave or the shape of a triangular wave is formed,
and it is impressed by the coil 2 for bias which are each magnetism
detecting elements 11A-11N of the magnetic sensor 12. A feed zone of
this bias current may be provided in the magnetic sensor 12 side.
[0070]Next, vehicle detection operation by composition of drawing 8 is
explained. First, an initial value of external magnetic field intensity used as
a standard for asking for external magnetic field intensity change in the
state where there are no vehicles is measured. For this reason, with the
magnetic sensor 12, a pulse signal which detected external magnetic field
intensity by two or more magnetism detecting elements 11A-11N, and
carried out Pulse Density Modulation is outputted as mentioned above, and
it sends to the selector 21 of the microcomputer judgment part 18.
[0071]With the command from the control section 19, the selector 21
chooses and sends two kinds of pulses A and B further mentioned above
while it chooses the output pulse signal of two or more magnetism
detecting elements 11A-11N which should be sent to the timer counter 20
one          by         one         and          sends          it.
[0072]In the timer counter 20, the pulse width of two kinds of said pulses
A and B of two or more magnetism detecting elements sent one by one is
counted and evaluated, and the data is sent to the control section 19.
[0073]In the control section 19, difference A-B of the pulse width data of
A pulse and B pulse evaluated with the timer counter 20 is computed for
every magnetism detecting element, and the measured value of external
magnetic field intensity is calculated. The measured data is recorded on
memory storage, such as RAM26 in the control section 19, as initial value
data           used             as           a           standard.
[0074]Then, in order to detect vehicles, the detection and the
Measurement Division of external magnetic field intensity by each
magnetism detecting element are performed in the same procedure as the
above, In the control section 19, it asks separately, absolute-value-izes by
using the difference of said measurement data and initial value data as
external magnetic field intensity change data, and asks for the total, and
the existence of vehicles is judged by whether it is over predetermined joint
threshold S which the total mentioned above. And in the case of the
vehicle detection system mentioned later, car presence information etc.
are taken out based on the result of said judgment.
[0075]In order not to treat the amplitude of a Colpitts oscillator as an
absolute value in the circuitry of the magnetism detecting element of
drawing 4 as an advantage of the equipment of these above embodiments
probably but to treat a changed part of amplitude, a low change of the
frequency by change, temperature characteristics, etc. of power supply
voltage             can              be             disregarded.
[0076]Since the detect output of the external magnetic field intensity in the
magnetic sensor 12 is digitized-output-ized by the Pulse Density
Modulation by a comparator, The magnetic sensor 12 and the
microcomputer judgment part 18 connect two or more magnetic sensors
12 to the microcomputer judgment part 18, and can carry out common use
of the microcomputer judgment part 18 to two or more magnetic sensors
12 while also being able to perform installation to isolate and obtaining the
flexibility               of                   installation.
[0077]Since the whole equipment which constituted the magnetism
detecting element very small, could constitute the magnetic sensor 12
small, and includes the microcomputer judgment part 18 can be made
small, The burden of installation cost is small, and it is low power
consumption, and since the prolonged energization use which was poor at
conventional loop coil type equipment is possible, the use of vehicle
detection                  is                 expandable.
[0078][Embodiment of a vehicle detection system] Next, drawing 9 and
drawing 10 explain the embodiment of the vehicle detection system for the
parking-vehicles management in the motor pool using the vehicle
detecting device of drawing 8 mentioned above. As for this vehicle
detection system, it is needless to say that the portion of the magnetic
sensor 12 is provided in the ground surface of a motor pool or
underground at least, and it carries out of the vehicle detecting device of
drawing                                  8.
[0079]Drawing 9 is a block diagram showing the functional composition of
the vehicle detection system of this embodiment. Composition of those
other than magnetic sensor 12 is specifically realized in drawing 9 by the
hardware and software of the microcomputer judgment part 18 of drawing
8.
[0080]In drawing 9, it realizes from the control section 19 of drawing 8,
the timer counter 20, and the selector 21, and the measurement means 27
measures the external magnetic field intensity change as on the basis of
the state where there are no vehicles based on the detection result of the
external magnetic field intensity by the magnetism detecting elements
11A-11N of the magnetic sensor 12 as mentioned above. This
measurement means 27 has the initial value memory measure 28 which
memorizes the value of the external magnetic field intensity detected by
the magnetism detecting elements 11A-11N in the state where there are no
vehicles as an initial value used as a standard, and measures external
magnetic field intensity change on the basis of the initial value memorized
to this memory measure 28. The memory measure 28 is specifically
constituted        as       RAM26         of       drawing         8.
[0081]It realizes as a function of the control section 19, and the vehicle
detection judging means 29 judges vehicle detection as mentioned above
based on the measuring result of the measurement means 27.
[0082]Penetration, a stop, and the **** judging means 30 are realized as
a function of processing of Step S3 of below-mentioned drawing 10 by the
control section 19, S6, and S9, Based on the decided result of the vehicle
detection by the vehicle detection judging means 29. [ whether vehicles
advanced into the motor pool, and ] It is judged whether on whether it
advanced on the magnetic sensor 12 formed in the motor pool, whether
whether whether it having stopped in the motor pool and a motor pool
having been left and vehicles stopped on the magnetic sensor 12, and the
magnetic           sensor           12          was            left.
[0083]Car presence and the **** information output means 31 are realized
as a function of Step S7 of drawing 10 by the control section 19, and
processing of S10, Based on the decided result of penetration, a stop, and
the **** judging means 30, vehicles have stopped at the motor pool, the
car presence information on the purport that vehicles have stopped on the
magnetic sensor 12, and vehicles left the motor pool, namely, vehicles
output the **** information on the purport that on the magnetic sensor 12
was                                    left.
[0084]External magnetic field intensity is detected by the basis of such
composition by the magnetism detecting elements 11A-11N of the
magnetic sensor 12, The external magnetic field intensity change on the
basis of the state where there are no vehicles by the measurement means
27 based on the detection result is measured, and the judgment of vehicle
detection is performed by the vehicle detection judging means 29 based
on the measuring result. And based on the decided result of vehicle
detection, penetration of the vehicles in a motor pool, a stop, and **** are
judged by the judging means 30, and car presence information thru/or ****
information are outputted by the output means 31 based on the decided
result.
[0085]Next, drawing 10 explains the details of vehicle detection operation
of this system. Drawing 10 is a flow chart which shows the procedure of
the vehicle detection processing by the control section 19 of drawing 8
which realizes each means 27, 29, 30, and 31 of drawing 9.
[0086]On vehicle detection processing and first in Step S1 of drawing 10
the control section 19, The external magnetic field intensity by each
magnetism detecting element of the magnetic sensor 12 is made to detect
as mentioned above in the state where there are no vehicles, It asks for the
measurement data of the external magnetic field intensity of A-B
mentioned above based on the detection result, this is set up as initial
value data used as the standard which asks for external magnetic field
intensity change, and it memorizes to the recording equipment of RAM26
grade. Since there are no vehicles into a motor pool at this time, the
control      section      19      checks      ****      information.
[0087]Next, in order to judge penetration of the vehicles to the magnetic
sensor 12 top formed in penetration of the vehicles into a motor pool, i.e.,
the ground surface of a motor pool, and underground, Detection and
Measurement Division of the external magnetic field intensity from the
vehicles by each magnetism detecting element are performed in the
procedure mentioned above (Step S2), It judges with vehicles having
advanced into the motor pool, when it absolute-value-ized in quest of the
difference of each measurement data A-B and initial value data separately
and the total was over predetermined joint threshold S, and when not
having progressed and exceeded for the following procedure, it returns to
Step                S2               (Step                S3).
[0088]When vehicles enter in a motor pool even in a front procedure, can
judge that, but. Since it thinks when passing without stopping then, after
judging penetration of vehicles at Step S3, detection and Measurement
Division of the external magnetic field intensity from the vehicles by each
magnetism detecting element are performed again (step S4), and it
compares with total of the absolute value of data A-B measured last time
(Step S5). When this measurement value is changing from the last
measurement value, it judges with vehicles moving in the inside of a motor
pool,         and         returns        to          step       S4.
[0089]Since it will be either when vehicles stop in a motor pool or a
passing car comes out out of a motor pool as it is if change of measured
value is lost, In order to carry out that judgment which is the any, in quest
of the difference of an initial value and measured-value-data A-B, it
absolute-value-izes separately by all the magnetism detecting elements, It
judges that the total is in the car presence state which vehicles have
stopped in a motor pool when total exceeds joint threshold S as compared
with the above-mentioned predetermined joint threshold S (that is, it has
stopped on the magnetic sensor 12) (Step S6), and car presence
information is taken out (Step S7). On the other hand, when total of the
absolute value of aforementioned difference A-B is not over joint threshold
S, it judges with the passing car having come out out of the motor pool as
it        is,       and        returns        to      Step        S2.
[0090]Next, detection of the magnetic field of the vehicles by each
magnetism detecting element in order to detect **** of the parked
vehicles, Measure (Step S8) and it absolute-value-izes in quest of the
difference of measurement data A-B and the data of an initial value
separately, When the total is over predetermined joint threshold S, vehicles
are judged continuously to be under parking, It returns to Step S8, and
when it repeated and is not over measurement, vehicles judge with having
left the inside of a motor pool (that is, on the magnetic sensor 12 was left),
take out **** information (Step S10), return to Step S2, and are again
repeated      from     detection     of     penetration    of   vehicles.
[0091]Thus, based on the detection result of the magnetic field from
vehicles, a stop and **** can be judged during penetration of the vehicles
in a motor pool, and movement, and car presence information and ****
information can be outputted. And the advantage of the vehicle detecting
device of this invention can be enjoyed, a stop and **** can be correctly
judged during penetration of vehicles, and movement by highly precise and
reliable vehicle detection, and exact car presence information and ****
information can be outputted. Therefore, the vehicle detection system of
this embodiment is effectively [ as management of parking vehicles /
because of management of parking duration, the empty area display in a
scale parking lot, vehicle guiding, etc. ] available.


DESCRIPTION OF DRAWINGS


[Brief        Description          of         the         Drawings]
[Drawing 1]It is an explanatory view showing the arrangement and the
direction of magnetic field detection over the vehicles of the magnetism
detecting element of the magnetic sensor in the embodiment of the vehicle
detecting         method           by        this         invention.
[Drawing 2]They are the explanatory view and graph charts showing the
situation of the external magnetic field intensity change by movement of
the vehicles detected with the magnetic sensor which comprised one
magnetism                  detecting                 element.
[Drawing 3]They are the explanatory view and graph charts showing the
magnetic field distribution of the cross direction of a bar magnet.
[Drawing 4]It is a circuit diagram showing the circuitry of the magnetism
detecting element of the magnetic sensor used for the embodiment of the
vehicle       detecting      device       by       this      invention.
[Drawing 5]They are graph charts showing the impedance change by the
AC bias magnetic field and external magnetic field of a magnetic
impedance            component              in         drawing          4.
[Drawing 6]It is a wave form chart showing the bias current Ib in drawing
4, the after-detection output of a detector circuit, and a comparator
output.
[Drawing 7]They are graph charts showing the pulse width and the count
number of a difference of the pulse which is two kinds from which the
pulse width of the comparator output to an external magnetic field differs.
[Drawing 8]It is a block diagram showing the composition of the
embodiment          of       a        vehicle       detecting        device.
[Drawing 9]It is a block diagram showing the functional composition of the
embodiment of the vehicle detection system by this invention.
[Drawing 10]It is a flow chart figure showing the vehicle detection
procedure        in        the       vehicle       detection        system.
[Explanations           of          letters         or          numerals]
1        A           magnetic            impedance             component
2            The                coil             for              bias
3                      Colpitts                     oscillator
4                      Detector                        circuit
5                                    Comparator
10                                     Vehicles
11A-11N             Magnetism               detecting            element
12                    Magnetic                   sensor
14                    Ground                    surface
18          Microcomputer               judgment              part
19                    Control                   section
20                     Timer                   counter
21                                 Selector
22                    Clock                   generator
23                     Clock                    divider
24                Low                pass               filter
25                      Bias                    circuit
26                                   RAM
27 The measurement means of external magnetic field intensity change
28        Initial          value         memory            measure
29       Vehicle           detection        judging           means
30   Penetration,   a   stop,    and    a    ****   judging   means
31 Car presence and a **** information output means


DRAWINGS


[Drawing                               1]




[Drawing                               2]
[Drawing   7]




[Drawing   3]
[Drawing   5]




[Drawing   4]
[Drawing   6]
[Drawing   8]
[Drawing   9]
[Drawing   10]
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Jp h09 237399

  • 1. JP,09-237399,A(1997) PATENT ABSTRACTS OF JAPAN (11)Publication number : 09-237399 (43)Date of publication of application : 09.09.1997 (51)Int.Cl. G08G 1/042 B60R 21/00 G01R 33/02 G01V 3/08 G01V 3/10 // G01C 21/00 (21)Application number : 08-0439 (71)Applicant : CANON ELECTRON 33 INC (22)Date of filing : 01.03.19 (72)Inventor : KAWASE MASAHIRO 96 TAZAKI SHINICHI (54) METHOD, DEVICE AND SYSTEM FOR VEHICLE DETECTION (57)Abstract: PROBLEM TO BE SOLVED: To improve reliability by making the magnetic detection of an vehicle highly precise through the use of a magnetic sensor consisting of plural small magnetic detection elements. SOLUTION: The magnetic sensor 12 plurally arranging along the longitudinal direction of the vehicle the magnetic detection elements 1A to 11N with magnetic field detecting sensitivity in a direction vertical to the ground is installed on or in the ground within the passing width of the vehicle. Through the use of a selector 21, a timer counter 20 and RAM 26 storing the early value of external magnetic intensity, a control part 19 measures each change of external magnetic field intensity basing on the state of no vehicle with
  • 2. respect to each magnetic detection element as a reference based on the intensity of external magnetic field detected by each magnetic detection element. Then the part 19 judges vehicle detection depending on whether the total sum of the respective absolute values of the measured values exceeds a prescribed combined threshold values. CLAIMS [Claim(s)] [Claim 1]In a vehicle detecting method which detects a magnetic field generated from vehicles with a magnetic sensor, and detects vehicles magnetically, A magnetic sensor which put in order two or more magnetism detecting elements which have magnetic field detection sensitivity in the direction vertical to a ground surface along with a vehicles longitudinal direction is installed in a ground surface in a band pass of vehicles, or underground, A vehicle detecting method detecting vehicles by the judgment of whether external magnetic field intensity change as on the basis of the state where each of two or more of said magnetism detecting elements detects external magnetic field intensity, and there are no vehicles is measured, and total of an absolute value of two or more measurement values of this measuring result exceeds predetermined joint threshold S. [Claim 2]The vehicle detecting method according to claim 1 setting said joint threshold S as a value of a product which hung threshold s in the case of one magnetism detecting element, and a square root of the addition numbers n of said measurement value added in order to ask for said total. [Claim 3]An absolute value of two or more measurement values of a measuring result of the aforementioned external magnetic field intensity change is arranged in descending, it is considered as |deltaH(k) | (k= 1, 2, ordinal number of --), and they are the following expression about this value, threshold s in the case of one magnetism detecting element, and a square root of said addition numbers n. [Mathematical formula 1]
  • 3. The vehicle detecting method according to claim 2 judging with having detected vehicles when it compared whether it is alike, it would set, would substitute one by one from k= 1, and the above-mentioned expression would be satisfied and the above-mentioned expression was satisfied. [Claim 4]The vehicle detecting method according to claim 2 or 3 setting threshold s in the case of said one magnetism detecting element as the range of 0.05-0.1 gauss. [Claim 5]It is a vehicle detecting device which detects a magnetic field generated from vehicles with a magnetic sensor, and detects vehicles magnetically, A magnetic sensor which consists of two or more magnetism detecting elements arranged so that it may have magnetic field detection sensitivity in the direction vertical to a ground surface and may rank with a ground surface in a band pass of vehicles, or underground along with a vehicles longitudinal direction, A measurement means which measures each of external magnetic field intensity change as on the basis of the state where there are no vehicles to each magnetism detecting element, based on external magnetic field intensity detected by each of two or more of said magnetism detecting elements, A vehicle detecting device having a judging means which judges vehicle detection by whether total of each absolute value of a measurement value of external magnetic field intensity change measured by this measurement means exceeds predetermined joint threshold S. [Claim 6]It has a memory measure which memorizes a value of external magnetic field intensity detected by said two or more magnetism detecting elements in the state where said measurement means does not have vehicles as an initial value used as a standard, The vehicle detecting device according to claim 5 measuring the aforementioned external magnetic field intensity change on the basis of an initial value memorized to this memory measure. [Claim 7]A Colpitts oscillator in which said magnetism detecting element incorporated a magnetic impedance component which attached a coil, It comprises a comparator [ predetermined comparison voltage / output / of
  • 4. a detector circuit which detects an output of this oscillator and this detector circuit ], By detecting external magnetic field intensity, applying an AC bias magnetic field to said magnetic impedance component with said coil, A Pulse-Density-Modulation output in which a pulse which is two kinds from which pulse width differs according to external magnetic field intensity in an output of said comparator appears by turns is obtained, The vehicle detecting device according to claim 5 or 6, wherein said measurement means measures external magnetic field intensity change as on the basis of the state where ask for data of a difference of pulse width of two kinds of said pulses as external magnetic field strength data, and said vehicles cannot be found based on this data. [Claim 8]It is a vehicle detection system which carries out vehicle detection to any 1 clause from Claim 5 to 7 using a vehicle detecting device of a description, A judging means which judges whether whether vehicles advanced on a magnetic sensor, whether it stopped on a magnetic sensor based on a decided result of vehicle detection by a judging means of said vehicle detecting device, and on a magnetic sensor were left, Car presence information on a purport that vehicles have stopped on a magnetic sensor based on a decided result of this judging means, And a vehicle detection system characterized by having an output means to which vehicles output **** information on a purport that on a magnetic sensor was left, and enabling it to manage parking vehicles with the output of said car presence information and **** information. DETAILED DESCRIPTION [Detailed Description of the Invention] [0001] [Field of the Invention]This invention detects the magnetic field generated from vehicles, such as a car, with a magnetic sensor, and detects vehicles magnetically, namely, relates to the vehicle detecting method which detects the existence of vehicles thru/or passage, a vehicle detecting device, and a vehicle detection system. [0002] [Description of the Prior Art]Conventionally, the sensor which detects vehicles, such as a car, is used in the use of measuring the distinction of
  • 5. the existence of parking in the managerial system of a motor pool, and the traffic of the vehicles in a traffic control system. [0003]Usually, since vehicles, such as a car, are tinged with magnetism using the metallic material which is easy to be tinged with magnetism, such as a steel plate, it is detecting the magnetic field generated from vehicles with a magnetic sensor, and it is possible to recognize existence of vehicles or passage. [0004]Conventionally, in the motor pool, the loop coil type magnetic sensor was buried in the earth, and it has been used for vehicle detection in it. A loop coil type magnetic sensor is that generate a magnetic field by an eddy current in the metal part of the body of vehicles to the alternating current sent through a coil, or the magnetic field from the body's own magnetization interlinks with a loop coil, A coil's own inductance changes, it is changed as change of oscillating frequency or amplitude in a circuit, and vehicle detection is performed by the existence of the change. [0005]However, although the loop coil type magnetic sensor is spreading by detection of vehicles, it has the following problems. [0006]- Since a loop coil opens an interval a little with vehicles and is installed, in order to detect the inductance variation in vehicles existence, there is the necessity of enlarging size of a sensitivity secured upper coil (about 1mx1m). [0007]- If metal bodies, such as a steel rod, are in the neighborhood, S/N cannot be taken enough. [0008]- Since a loop coil is large and power consumption is large, it is not fit for continuous energization use. [0009]- A coil is a size which is about 1mx1m, and the burden of construction expense is heavy in subterranean installation. [0010]Then, although the small magnetic sensor was used and the substitution was considered, When the magnetic field generated from a vehicles pars basilaris ossis occipitalis was measured, near the zero crossing point which remarkable unevenness is made to distribution of magnetic field strength, and magnetic field polarity reverses by the local magnetization of Body Manufacturing Division article each which it has, it turned out that the dead point which does not exceed a threshold required for the judgment of vehicle detection arises. [0011]
  • 6. [Problem to be solved by the invention]Then, a reliable vehicle detecting method in which SUBJECT of this invention can perform magnetic detection of vehicles with high precision using the magnetic sensor which consists of two or more small magnetism detecting elements, And it is in providing the vehicle detection system which is a vehicle detecting device which performs vehicle detection by the method, can attain a miniaturization and can be used effective in management of parking vehicles using the vehicle detecting device of low power consumption, and this vehicle detecting device. [0012] [Means for solving problem]In the vehicle detecting method which according to this invention detects the magnetic field generated from vehicles with a magnetic sensor, and detects vehicles magnetically in order to solve above-mentioned SUBJECT, The magnetic sensor which put in order two or more magnetism detecting elements which have magnetic field detection sensitivity in the direction vertical to a ground surface along with the vehicles longitudinal direction is installed in the ground surface in the band pass of vehicles, or underground, The external magnetic field intensity change as on the basis of the state where each of two or more of said magnetism detecting elements detects external magnetic field intensity, and there are no vehicles was measured, and the method of detecting vehicles by the judgment of whether total of the absolute value of two or more measurement values of this measuring result exceeds predetermined joint threshold S was adopted. [0013]According to such a vehicle detecting method, the influence of the zero crossing point which the magnetic field polarity looked at by distribution of the magnetic field strength in the case of measuring the magnetic field generated from a vehicles pars basilaris ossis occipitalis reverses can be avoided, and highly precise and reliable vehicle detection can be performed. [0014]According to this invention, it is a vehicle detecting device which detects the magnetic field generated from vehicles with a magnetic sensor, and detects vehicles magnetically, The magnetic sensor which consists of two or more magnetism detecting elements arranged so that it may have magnetic field detection sensitivity in the direction vertical to a ground surface and may rank with the ground surface in the band pass of
  • 7. vehicles, or underground along with a vehicles longitudinal direction, The measurement means which measures each of external magnetic field intensity change as on the basis of the state where there are no vehicles to each magnetism detecting element, based on the external magnetic field intensity detected by each of two or more of said magnetism detecting elements, Total of each absolute value of the measurement value of external magnetic field intensity change measured by this measurement means adopted the composition of the vehicle detecting device which has a judging means which judges vehicle detection by whether predetermined joint threshold S is exceeded. [0015]While being able to perform reliable vehicle detection with high degree of accuracy with the vehicle detecting method of this invention according to such composition, the magnetic sensor can consist of small size which consists of plurality of the small magnetism detecting element constituted, for example using the magnetic impedance component as a magnetic sensor of low power consumption. [0016]It is a vehicle detection system which performs vehicle detection using the vehicle detecting device by above-mentioned this invention according to this invention, The judging means which judges whether whether vehicles advanced on the magnetic sensor, whether it stopped on the magnetic sensor based on the decided result of the vehicle detection by the judging means of said vehicle detecting device, and on the magnetic sensor were left, The car presence information on the purport that vehicles have stopped on a magnetic sensor based on the decided result of this judging means, And it has an output means to which vehicles output the **** information on the purport that on the magnetic sensor was left, and the composition of the vehicle detection system which enabled it to manage parking vehicles with the output of said car presence information and **** information was adopted. [0017]According to such composition, the advantage of the vehicle detecting device of this invention can be enjoyed, exact car presence information and **** information can be outputted based on highly precise and reliable vehicle detection, and it can use effective in management of parking vehicles. [0018] [Mode for carrying out the invention]Hereafter, an embodiment of the
  • 8. invention is described with reference to figures. [0019][Embodiment of a vehicle detecting method] Drawing 1 - 3 explain the embodiment of the vehicle detecting method by this invention first. [0020]In this embodiment, as shown in drawing 1, to the ground surface 14 in the width which the vehicles (car) 10 pass, or underground. The magnetic sensor 12 which has arranged two or more magnetism detecting elements 11A, 11B, and 11C which have magnetic field detection sensitivity in the direction (Z direction) vertical to a ground surface so that it may stand in a line along with the longitudinal direction of the vehicles 10 is installed, and vehicle detection is performed. [0021]The external magnetic field intensity change as on the basis of the state where each magnetism detecting element of the magnetic sensor 12 detects external magnetic field intensity, and there are no vehicles 10 is measured, and total of the absolute value of two or more measured magnetic-field-strength change detects vehicles by the judgment of whether to exceed a predetermined joint threshold. [0022]This method was drawn from the following examining results. [0023]First, on the ground surface 14 in the width which the vehicles 10 pass as shown in drawing 2, The magnetic sensor 12 which comprised one magnetism detecting element which has magnetic field detection sensitivity in the Z direction which is a vertical direction to the ground surface 14 is arranged, the vehicles 10 were moved on the sensor 12, the magnetic sensor 12 detected external magnetic field intensity, external magnetic field intensity change was measured, and the situation of the change was investigated. The variation of external magnetic field intensity made the measurement value in the state where there are no vehicles 10 the initial value used as a standard, and displayed a changed part from it. The element using the magnetic impedance component mentioned later as a magnetic sensing device was used for the magnetism detecting element. Two or more vehicles performed the sampling. Four data measuring of a characteristic example is shown in drawing 2 (a) - (d) in it. [0024]Generally, magnetic field distribution of the cross direction of a bar magnet has a peak of reverse polarity at both ends of the bar magnet 16 like drawing 3, and has a tendency which carries out a zero cross in the center section. On the other hand, it can guess that the body of a car constitutes a roughly big bar magnet from a vehicles longitudinal direction
  • 9. from it being in agreement with how of data measuring of drawing 2 to lengthen the skirt near the both-ends peak of magnetic field distribution of drawing 3 by (c) and (d), especially, if it observes near the both ends of a magnetic field change. However, attitude of a peak has dispersion considerably by overall magnetic-field-strength distribution, and it does not become a beautiful form like a bar magnet because local magnetization exists by part each of a body pars basilaris ossis occipitalis. [0025]Since detection of vehicles will detect a magnetic field of a body center section if detection of parking vehicles is taken into consideration, for example, it observes a magnetic field of a center of the body by width of the length of a half of the body shown in the range of H seal in a figure of each data measuring of drawing 2. It is because movement speed of a difference in the length of each body and the body at the time of Measurement Division had dispersion that the length of H seal differs. [0026]Also when unevenness is looked at by magnetic-field-strength change within the limits of H seal of data of four examples and a zero cross exists, an absolute value of a measurement value may go into a DETTO point on which it is less than threshold s, and one magnetism detecting element is not enough as it for vehicle detection at a certain thing. [0027]When threshold s of one magnetism detecting element considers resolution of a magnetism detecting element, and S/N of a circuit, 0.05 gauss of a minimum is a limit, and considering that a maximum has about 0.1 gauss vehicles like drawing 2 (c) in the maximum of a magnetic field change by vehicles, it is difficult to set up exceeding 0.1 gauss. [0028]Then, two or more magnetism detecting elements are arranged along with a vehicles longitudinal direction, and if vehicle detection is carried out by whether either exceeds threshold s, detection probability will increase. [0029]However, in a case of vehicles of drawing 2 (d), when four magnetism detecting elements have been arranged to each of a position corresponding to four points, a in a figure, b, c, and d, a measurement value by which element will also be less than 0.05 gauss. If such a case is taken into consideration, a device which raises detection probability further is required.
  • 10. [0030]Then, an absolute value of a measurement value of two or more magnetic-field-strength change which detected external magnetic field intensity by each of two or more magnetism detecting elements, and was measured is added, A value of a product which, on the other hand, hung said number (addition numbers of a measurement value) n of a magnetism detecting element of added square roots on threshold s at the time of detection by an independent magnetism detecting element is set up as joint threshold S, If vehicle detection is judged by whether total of an added result of said absolute value exceeds joint threshold S, it is detectable by high probabilities. [0031]A noise component serves as a mean square to addition of an output of each magnetism detecting element, and if it is considered as a noise component of the respectively same size, this will use that a product of a noise for one element and a square root of the addition numbers n serves as a noise at the time of combination, and will try to earn the whole S/N. [0032]For example, magnetic-field-strength change, a of the data measuring of the vehicles of drawing 2 (d), b, c, and d, of four points, It will be 0.03G-0.04G-0.02G-0.03G, and if threshold s of independent detection is set to 0.05G, when these are added, it will be 0.12G, and 0.05xroot4=0.1 gauss is set to joint threshold S, total of the added result of an output will exceed joint threshold S, and detection of it will be attained. [0033]Therefore, when the magnetic field component of a direction vertical to the ground surface of the magnetic field generated from vehicles is detected by two or more Magnetism detecting elementn and the magnetic-field-strength change by vehicles existence is measured, It turned out that it is suitable that the total adding each of the absolute value of magnetic-field-strength change measured based on the detection result of n magnetism detecting elements of a result performs vehicle detection by whether joint threshold S as independent threshold sxrootn is exceeded. [0034]By the way, since a magnetic-field-detection output may become near a zero cross with a certain element and total of the above-mentioned added result may become low when detecting as mentioned above by two or more magnetism detecting elements, the method explained below can
  • 11. also be chosen as a method of raising vehicle detection efficiency further. [0035]Arrange in descending each absolute value of the measurement value of the external magnetic field intensity change from the initial value which detected external magnetic field intensity by two or more magnetism detecting elements of the magnetic sensor mentioned above, and was measured, consider it as |deltaH(k) | (k= 1, 2, ordinal number of --), and Namely, this value, They are [ threshold s in the case of one magnetism detecting element, and ] the following expression about said addition numbers n.[0036] [Mathematical formula 2] [0037]It compares whether it is alike, it sets, substitutes one by one from k= 1, and the above-mentioned expression is satisfied, and when the above-mentioned expression is satisfied, it judges with having detected vehicles. [0038]According to this method, vehicle detection efficiency can be raised by adding the measurement value of two or more external magnetic field intensity change to descending one by one, and using for the judgment of vehicle detection. [0039]In above-mentioned explanation, the "ground surface of "underground" meaning the inside of those fields including all the fields that vehicles, such as a floor line in the building of not only the ground surface of the ground, and the road surface of a road and the ground surface of an outdoor parking lot but a multi-level car parking tower, run fields thru/or park" of 14 is natural. [0040][Embodiment of a vehicle detecting device] Next, the embodiment of a vehicle detecting device which enforces concretely the vehicle detecting method mentioned above, and performs vehicle detection is described. [0041]First, the magnetism detecting element of the magnetic sensor used for a vehicle detecting device is explained. Being required of this magnetism detecting element should be 10 or more milligauss in (1) magnetic field detection sensitivity.
  • 12. [0042](2) There is two or more dispersion [ little ] of the performance of an element for use. [0043](3) Considering ground surface installation, the height of an element should be several millimeters. [0044](4) The detector circuit of an element is excellent in a noise-proof and temperature characteristics, and be low power consumption. [0045]Although there is a flux gate type magnetism detecting element as what satisfies the conditions of (1), if it is going to raise detection sensitivity with this element, several 10 mm of the length of an element will be needed, and it will not be satisfied with it of the conditions of (3). [0046]Since it is easy to come out of dispersion in performance, a problem produces a flux gate type magnetism detecting element also on condition of (2). [0047]Then, the magnetism detecting element constituted using a magnetic impedance component is seemed that it is the optimal by it. [0048]The magnetic impedance component is indicated by JP,H7-181239,A and the element body as a magnetic body is constituted from an amorphous wire or these days by the magnetic thin film etc. If the high frequency current of an MHz band is impressed to this element body, according to a magnetic impedance effect, according to an external magnetic field, the impedance of an element body changes several 10%, and can detect an external magnetic field using this. [0049]Sensitivity of a magnetic impedance component has the sensitivity of a 10-5 gauss stand, and number milligauss is securable and it is satisfied also with practical resolution in a case where it connects with a circuit of a magnetism detecting element of conditions of (1). [0050]From there being little influence of a demagnetizing field, it is easy for the length of an element to be 5 mm or less, and conditions of (3) are also cleared. [0051]About dispersion in performance, when supplied with an amorphous wire, since it is easy to control thickness, dispersion in performance resulting from an outside dimension of a magnetic body of an element body is pressed down, and is satisfied with that there is little dispersion in a path of a wire, and a magnetic film of conditions of (2). [0052]Although application was considered according to contents reported at a society etc. about magnetic field detection which uses the
  • 13. Colpitts oscillating circuit about conditions of (4), there is a problem practically. [0053]For example, an application of a magnetic field sensor as an azimuth sensor is shown by an "amorphous wire MI Colpitts oscillation type micro magnetic sensor" announced at the 18th Maganetics Society of Japan academic lecture meeting (14pB-7). [0054]In composition of this azimuth sensor, an amorphous wire is included in a Colpitts type oscillator, and since change of an external magnetic field turns into change of oscillation amplitude and it appears, an output is obtained through a detector circuit. While sending a direct current through a coil directly twisted around a wire of an element, applying a DC bias magnetic field and making it operate in a field where sensitivity is high, he is trying to know the polarity of the direction of north and south. [0055]However, in minute magnetic field detection, such as geomagnetism (about 0.3 gauss) by this method. Change of an output after a detector circuit is as small as several percent, and in order to treat absolute value change of oscillation amplitude as an output as it is, sufficient S/N is not obtained from it being easy to be influenced by change of power supply voltage, the temperature characteristics of an element, etc. by amplitude fluctuation, and it is unreliable. [0056]So, in this embodiment, circuitry of a magnetism detecting element shown in drawing 4 was adopted. [0057]Circuitry of a magnetism detecting element shown in drawing 4 consists of a Colpitts oscillator, a detector circuit, and a comparator, the magnetic impedance component 1 mentioned above is included in a Colpitts oscillator, it direct-winds, or the magnetic impedance component 1 is approached, and the coil 2 for bias is formed. [0058]In this composition, AC bias current Ib is sent through the coil 2, and an about **1-**2 gauss AC bias magnetic field is impressed to the magnetic impedance component 1. As shown in (a), amplitude modulation of the oscillation output which appears like the after-mentioned by this at an A point in a figure of a Colpitts oscillator according to intensity of the external magnetic field Hex for [ which is impressed to the magnetic impedance component 1 ] detection is carried out, A ripple waveform corresponding to a bias magnetic field which has the difference of elevation of an adjacent peak corresponding to intensity of the external
  • 14. magnetic field Hex by detecting this in a detector circuit at a B point as shown in (b) is acquired, By carrying out a party rate with the comparison voltage Vref which crosses a voltage waveform of said ripple with a comparator, a Pulse-Density-Modulation output corresponding to intensity of the external magnetic field Hex can be obtained at C point. [0059]A signal of AC bias current Ib carries out dividing of the clock from a microcomputer judgment part mentioned later, with a low pass filter, it may be made into a sine wave or the shape of a triangular wave, and it may throw it in, or may provide and throw in an oscillator individually. [0060]Next, details of operation of circuitry of a magnetism detecting element of drawing 4 mentioned above are explained. [0061]the characteristic of a magnetic impedance component is symmetrical with the direction of +- in several gauss to the external magnetic field Hex, as shown in drawing 5 -- a V character-like impedance change is shown in general. As shown in drawing 5 (a) as a principle of operation of the magnetic impedance component 1 of drawing 4, when there is no external magnetic field, an AC bias magnetic field is +. - It touches symmetrically, In change of impedance to it, an impedance change which the difference of elevation does not have in peaks on a ripple breaks out by a magnetic field twice the frequency of AC bias. [0062]Since an AC bias magnetic field and an unsymmetrical magnetic field which an external magnetic field superimposed will start the magnetic impedance component 1 like drawing 5 (b) there if an external magnetic field is impressed to a longitudinal direction of the magnetic impedance component 1, An impedance change (ripple waveform) from which height of a peak differs by turns on an impedance change arises. [0063]The ripple waveform in an impedance change as showed the output after detection of drawing 4 (b) which appeared as amplitude modulation in the oscillation amplitude characteristic of the Colpitts oscillator as change of this impedance was shown in drawing 4 (a), and detected that oscillation output in the detector circuit by drawing 5 (b), and a similar signal are acquired. The size of an external magnetic field is changed into the output of a digital signal by which Pulse Density Modulation was carried out by carrying out a party rate with the comparison voltage Vref which crosses a ripple waveform as the signal is shown in drawing 6 in a comparator. That is, the Pulse-Density-Modulation output in which the
  • 15. pulse which is two kinds from which pulse width differs according to external magnetic field intensity appears by turns is obtained. [0064]Thus, pulse width [ of two kinds of pulses ] A which appears by turns, and B can be measured and evaluated using the timer counter of a microcomputer, and the digital data in which external magnetic field intensity is shown can be obtained by asking for the digital data of difference A-B of pulse width by an operation after that. Although the measurement data of pulse width to a actual external magnetic field is shown in drawing 7, in **0.5 gauss shows an almost linear change. The numerical input value of joint threshold S mentioned above can be decided by transposing the magnetic field strength of magnetism detecting element independent threshold s to the math-processing value of pulse width based on this data, and hanging the several n square root of a magnetism detecting element on it. [0065]And the digital data of difference A-B of the pulse width measured in the state where there are no vehicles, in detection of vehicles is memorized as data of the initial value of the external magnetic field intensity used as a standard, Then, the absolute value of the difference of difference A-B of pulse width and the initial value according to the measured external magnetic field intensity is calculated as data corresponding to the absolute value of intensity change of an external magnetic field, It can ask for total of the data of said absolute value called for by further two or more magnetism detecting elements, and the existence of vehicles can be judged by whether the figure exceeded the numerical value of joint threshold S. [0066]Next, drawing 8 explains the composition of the vehicle detecting device using the magnetism detecting element of drawing 4. [0067]Colpitts oscillator 3 incorporating the magnetic impedance component 1 which wound the coil 2 for bias which 12 is a magnetic sensor and was mentioned above in the composition of the vehicle detecting device shown in drawing 8, They are the marks 11A and 11B about the magnetism detecting element of drawing 4 which consists of the detector circuit 4 and the comparator 5. -- As shown in 11N, N pieces are provided and it is constituted. Magnetism detecting elements 11A and 11B -- 11N is arranged so that it may rank with the ground surface in the band pass of vehicles, or underground along with the longitudinal direction of
  • 16. vehicles as mentioned above, and each element can be giving magnetic field detection sensitivity in the direction vertical to a ground surface. [0068]18 is a microcomputer judgment part which comprises a microcomputer, analyzes the Pulse-Density-Modulation output of each magnetism detecting element of the magnetic sensor 12, and judges the existence of vehicles. The microcomputer judgment part 18, Either the timer counter 20 which counts pulse width [ of the control section 19 which performs whole control and various data processing, and the Pulse- Density-Modulation output mentioned above ] A, and B or magnetism detecting elements 11A-11N are chosen. It consists of the selector 21 which inputs the output pulse into the timer counter 20 and the clock generator 22, the clock divider 23, the low pass filter 24, and the bias circuit (amplifier) 25. [0069]Dividing is carried out so that the clock signal which the clock generator 22 oscillates may become the range of 1 kHz - 100 kHz by the clock divider 23 in this composition, The low pass filter 24 and the bias circuit 25 let this signal by which dividing was carried out pass, the signal of the AC bias current of a sine wave or the shape of a triangular wave is formed, and it is impressed by the coil 2 for bias which are each magnetism detecting elements 11A-11N of the magnetic sensor 12. The feed zone of this bias current may be provided in the magnetic sensor 12 side. [0070]Next, the vehicle detection operation by the composition of drawing 8 is explained. First, the initial value of the external magnetic field intensity used as the standard for asking for external magnetic field intensity change in the state where there are no vehicles is measured. For this reason, with the magnetic sensor 12, the pulse signal which detected external magnetic field intensity by two or more magnetism detecting elements 11A-11N, and carried out Pulse Density Modulation is outputted as mentioned above, and it sends to the selector 21 of the microcomputer judgment part 18. [0071]With the command from the control section 19, the selector 21 chooses and sends two kinds of pulses A and B further mentioned above while it chooses the output pulse signal of two or more magnetism detecting elements 11A-11N which should be sent to the timer counter 20 one by one and sends it. [0072]In the timer counter 20, the pulse width of two kinds of said pulses
  • 17. A and B of two or more magnetism detecting elements sent one by one is counted and evaluated, and the data is sent to the control section 19. [0073]In the control section 19, difference A-B of the pulse width data of A pulse and B pulse evaluated with the timer counter 20 is computed for every magnetism detecting element, and the measured value of external magnetic field intensity is calculated. The measured data is recorded on memory storage, such as RAM26 in the control section 19, as initial value data used as a standard. [0074]Then, in order to detect vehicles, the detection and the Measurement Division of external magnetic field intensity by each magnetism detecting element are performed in the same procedure as the above, In the control section 19, it asks separately, absolute-value-izes by using the difference of said measurement data and initial value data as external magnetic field intensity change data, and asks for the total, and the existence of vehicles is judged by whether it is over predetermined joint threshold S which the total mentioned above. And in the case of the vehicle detection system mentioned later, car presence information etc. are taken out based on the result of said judgment. [0075]In order not to treat the amplitude of a Colpitts oscillator as an absolute value in the circuitry of the magnetism detecting element of drawing 4 as an advantage of the equipment of these above embodiments probably but to treat a changed part of amplitude, a low change of the frequency by change, temperature characteristics, etc. of power supply voltage can be disregarded. [0076]Since the detect output of the external magnetic field intensity in the magnetic sensor 12 is digitized-output-ized by the Pulse Density Modulation by a comparator, The magnetic sensor 12 and the microcomputer judgment part 18 connect two or more magnetic sensors 12 to the microcomputer judgment part 18, and can carry out common use of the microcomputer judgment part 18 to two or more magnetic sensors 12 while also being able to perform installation to isolate and obtaining the flexibility of installation. [0077]Since the whole equipment which constituted the magnetism detecting element very small, could constitute the magnetic sensor 12 small, and includes the microcomputer judgment part 18 can be made small, The burden of installation cost is small, and it is low power
  • 18. consumption, and since the prolonged energization use which was poor at conventional loop coil type equipment is possible, the use of vehicle detection is expandable. [0078][An embodiment of a vehicle detection system] Next, drawing 9 and drawing 10 explain an embodiment of a vehicle detection system for parking-vehicles management in a motor pool using a vehicle detecting device of drawing 8 mentioned above. As for this vehicle detection system, it is needless to say that a portion of the magnetic sensor 12 is provided in a ground surface of a motor pool or underground at least, and it carries out of a vehicle detecting device of drawing 8. [0079]Drawing 9 is a block diagram showing functional composition of a vehicle detection system of this embodiment. Composition of those other than magnetic sensor 12 is specifically realized in drawing 9 by hardware and software of the microcomputer judgment part 18 of drawing 8. [0080]In drawing 9, it realizes from the control section 19 of drawing 8, the timer counter 20, and the selector 21, and the measurement means 27 measures external magnetic field intensity change as on the basis of the state where there are no vehicles based on a detection result of external magnetic field intensity by the magnetism detecting elements 11A-11N of the magnetic sensor 12 as mentioned above. This measurement means 27 has the initial value memory measure 28 which memorizes a value of external magnetic field intensity detected by the magnetism detecting elements 11A-11N in the state where there are no vehicles as an initial value used as a standard, and measures external magnetic field intensity change on the basis of an initial value memorized to this memory measure 28. The memory measure 28 is specifically constituted as RAM26 of drawing 8. [0081]It realizes as a function of the control section 19, and the vehicle detection judging means 29 judges vehicle detection as mentioned above based on the measuring result of the measurement means 27. [0082]Penetration, a stop, and the **** judging means 30 are realized as a function of processing of Step S3 of below-mentioned drawing 10 by the control section 19, S6, and S9, Based on the decided result of the vehicle detection by the vehicle detection judging means 29. [ whether vehicles advanced into the motor pool, and ] It is judged whether on whether it advanced on the magnetic sensor 12 formed in the motor pool, whether
  • 19. whether whether it having stopped in the motor pool and a motor pool having been left and vehicles stopped on the magnetic sensor 12, and the magnetic sensor 12 was left. [0083]Car presence and the **** information output means 31 are realized as a function of Step S7 of drawing 10 by the control section 19, and processing of S10, Based on the decided result of penetration, a stop, and the **** judging means 30, vehicles have stopped at the motor pool, the car presence information on the purport that vehicles have stopped on the magnetic sensor 12, and vehicles left the motor pool, namely, vehicles output the **** information on the purport that on the magnetic sensor 12 was left. [0084]External magnetic field intensity is detected by the basis of such composition by the magnetism detecting elements 11A-11N of the magnetic sensor 12, The external magnetic field intensity change on the basis of the state where there are no vehicles by the measurement means 27 based on the detection result is measured, and the judgment of vehicle detection is performed by the vehicle detection judging means 29 based on the measuring result. And based on the decided result of vehicle detection, penetration of the vehicles in a motor pool, a stop, and **** are judged by the judging means 30, and car presence information thru/or **** information are outputted by the output means 31 based on the decided result. [0085]Next, drawing 10 explains the details of vehicle detection operation of this system. Drawing 10 is a flow chart which shows the procedure of the vehicle detection processing by the control section 19 of drawing 8 which realizes each means 27, 29, 30, and 31 of drawing 9. [0086]On vehicle detection processing and first in Step S1 of drawing 10 the control section 19, External magnetic field intensity by each magnetism detecting element of the magnetic sensor 12 is made to detect as mentioned above in the state where there are no vehicles, It asks for measurement data of external magnetic field intensity of A-B mentioned above based on the detection result, this is set up as initial value data used as a standard which asks for external magnetic field intensity change, and it memorizes to recording equipment of RAM26 grade. Since there are no vehicles into a motor pool at this time, the control section 19 checks **** information.
  • 20. [0087]Next, in order to judge penetration of vehicles to the magnetic sensor 12 top formed in penetration of vehicles into a motor pool, i.e., a ground surface of a motor pool, and underground, Detection and Measurement Division of external magnetic field intensity from vehicles by each magnetism detecting element are performed in a procedure mentioned above (Step S2), It judges with vehicles having advanced into a motor pool, when it absolute-value-ized in quest of a difference of each measurement data A-B and initial value data separately and the total was over predetermined joint threshold S, and when not having progressed and exceeded for the following procedure, it returns to Step S2 (Step S3). [0088]When vehicles enter in a motor pool even in a front procedure, can judge that, but. Since it thinks when passing without stopping then, after judging penetration of vehicles at Step S3, detection and Measurement Division of the external magnetic field intensity from the vehicles by each magnetism detecting element are performed again (step S4), and it compares with total of the absolute value of data A-B measured last time (Step S5). When this measurement value is changing from the last measurement value, it judges with vehicles moving in the inside of a motor pool, and returns to step S4. [0089]Since it will be either when vehicles stop in a motor pool or a passing car comes out out of a motor pool as it is if change of measured value is lost, In order to carry out that judgment which is the any, in quest of the difference of an initial value and measured-value-data A-B, it absolute-value-izes separately by all the magnetism detecting elements, It judges that the total is in the car presence state which vehicles have stopped in a motor pool when total exceeds joint threshold S as compared with the above-mentioned predetermined joint threshold S (that is, it has stopped on the magnetic sensor 12) (Step S6), and car presence information is taken out (Step S7). On the other hand, when total of the absolute value of aforementioned difference A-B is not over joint threshold S, it judges with the passing car having come out out of the motor pool as it is, and returns to Step S2. [0090]Next, detection of the magnetic field of the vehicles by each magnetism detecting element in order to detect **** of the parked vehicles, Measure (Step S8) and it absolute-value-izes in quest of the difference of measurement data A-B and the data of an initial value
  • 21. separately, When the total is over predetermined joint threshold S, vehicles are judged continuously to be under parking, It returns to Step S8, and when it repeated and is not over measurement, vehicles judge with having left the inside of a motor pool (that is, on the magnetic sensor 12 was left), take out **** information (Step S10), return to Step S2, and are again repeated from detection of penetration of vehicles. [0091]Thus, based on the detection result of the magnetic field from vehicles, a stop and **** can be judged during penetration of the vehicles in a motor pool, and movement, and car presence information and **** information can be outputted. And the advantage of the vehicle detecting device of this invention can be enjoyed, a stop and **** can be correctly judged during penetration of vehicles, and movement by highly precise and reliable vehicle detection, and exact car presence information and **** information can be outputted. Therefore, the vehicle detection system of this embodiment is effectively [ as management of parking vehicles / because of management of parking duration, the empty area display in a scale parking lot, vehicle guiding, etc. ] available. [0092] [Effect of the Invention]According to the vehicle detecting method of this invention, so that clearly from the above explanation to the ground surface in the band pass of vehicles, or underground. The magnetic sensor which put in order two or more magnetism detecting elements which have magnetic field detection sensitivity in the direction vertical to a ground surface along with the vehicles longitudinal direction is installed, The external magnetic field intensity change as on the basis of the state where each of a magnetism detecting element detects external magnetic field intensity, and there are no vehicles is measured, Since total of the absolute value of two or more measurement values of this measuring result was made to detect vehicles by the judgment of whether to exceed predetermined joint threshold S, The influence of the zero crossing point which the magnetic field polarity looked at by distribution of the magnetic field strength in the case of measuring the magnetic field generated from a vehicles pars basilaris ossis occipitalis reverses can be avoided, and highly precise and reliable vehicle detection can be performed. [0093]While being able to perform reliable vehicle detection with high degree of accuracy with the vehicle detecting method of this invention
  • 22. according to the vehicle detecting device of this invention, a magnetic sensor, For example, it can constitute from small size which consists of plurality of the small magnetism detecting element constituted using the magnetic impedance component as a magnetic sensor of low power consumption, Compared with the equipment using the conventional loop coil type sensor, prolonged continuous use is possible, installation can also be easily performed by low cost, and the use of vehicle detection can be expanded. [0094]According to the vehicle detection system using the vehicle detecting device of this invention. By vehicle detection enjoy the advantage of the vehicle detecting device of this invention, highly precise and reliable, exact car presence information, **** information can be outputted and the outstanding effect of being available is acquired effectively [ because of management of parking duration, the empty area display in a scale parking lot, vehicle guiding, etc. ] as management of parking vehicles. TECHNICAL FIELD [Field of the Invention]This invention detects the magnetic field generated from vehicles, such as a car, with a magnetic sensor, and detects vehicles magnetically, namely, relates to the vehicle detecting method which detects the existence of vehicles thru/or passage, a vehicle detecting device, and a vehicle detection system. PRIOR ART [Description of the Prior Art]Conventionally, the sensor which detects vehicles, such as a car, is used in the use of measuring the distinction of the existence of parking in the managerial system of a motor pool, and the traffic of the vehicles in a traffic control system. [0003]Usually, since vehicles, such as a car, are tinged with magnetism using the metallic material which is easy to be tinged with magnetism, such as a steel plate, it is detecting the magnetic field generated from vehicles with a magnetic sensor, and it is possible to recognize existence of vehicles or passage.
  • 23. [0004]Conventionally, in the motor pool, the loop coil type magnetic sensor was buried in the earth, and it has been used for vehicle detection in it. A loop coil type magnetic sensor is that generate a magnetic field by an eddy current in the metal part of the body of vehicles to the alternating current sent through a coil, or the magnetic field from the body's own magnetization interlinks with a loop coil, A coil's own inductance changes, it is changed as change of oscillating frequency or amplitude in a circuit, and vehicle detection is performed by the existence of the change. [0005]However, although the loop coil type magnetic sensor is spreading by detection of vehicles, it has the following problems. [0006]- Since a loop coil opens an interval a little with vehicles and is installed, in order to detect the inductance variation in vehicles existence, there is the necessity of enlarging size of a sensitivity secured upper coil (about 1mx1m). [0007]- If metal bodies, such as a steel rod, are in the neighborhood, S/N cannot be taken enough. [0008]- Since a loop coil is large and power consumption is large, it is not fit for continuous energization use. [0009]- A coil is a size which is about 1mx1m, and the burden of construction expense is heavy in subterranean installation. [0010]Then, although the small magnetic sensor was used and the substitution was considered, When the magnetic field generated from a vehicles pars basilaris ossis occipitalis was measured, near the zero crossing point which remarkable unevenness is made to distribution of magnetic field strength, and magnetic field polarity reverses by the local magnetization of Body Manufacturing Division article each which it has, it turned out that the dead point which does not exceed a threshold required for the judgment of vehicle detection arises. EFFECT OF THE INVENTION [Effect of the Invention]According to the vehicle detecting method of this invention, so that clearly from the above explanation to the ground surface in the band pass of vehicles, or underground. The magnetic sensor which put in order two or more magnetism detecting elements which have magnetic field detection sensitivity in the direction vertical to a ground
  • 24. surface along with the vehicles longitudinal direction is installed, The external magnetic field intensity change as on the basis of the state where each of a magnetism detecting element detects external magnetic field intensity, and there are no vehicles is measured, Since total of the absolute value of two or more measurement values of this measuring result was made to detect vehicles by the judgment of whether to exceed predetermined joint threshold S, The influence of the zero crossing point which the magnetic field polarity looked at by distribution of the magnetic field strength in the case of measuring the magnetic field generated from a vehicles pars basilaris ossis occipitalis reverses can be avoided, and highly precise and reliable vehicle detection can be performed. [0093]While being able to perform reliable vehicle detection with high degree of accuracy with the vehicle detecting method of this invention according to the vehicle detecting device of this invention, a magnetic sensor, For example, it can constitute from small size which consists of plurality of the small magnetism detecting element constituted using the magnetic impedance component as a magnetic sensor of low power consumption, Compared with the equipment using the conventional loop coil type sensor, prolonged continuous use is possible, installation can also be easily performed by low cost, and the use of vehicle detection can be expanded. [0094]According to the vehicle detection system using the vehicle detecting device of this invention. By vehicle detection enjoy the advantage of the vehicle detecting device of this invention, highly precise and reliable, exact car presence information, **** information can be outputted and the outstanding effect of being available is acquired effectively [ because of management of parking duration, the empty area display in a scale parking lot, vehicle guiding, etc. ] as management of parking vehicles. TECHNICAL PROBLEM [Problem to be solved by the invention]Then, a reliable vehicle detecting method in which SUBJECT of this invention can perform magnetic detection of vehicles with high precision using a magnetic sensor which consists of two or more small magnetism detecting elements, And it is in
  • 25. providing a vehicle detection system which is a vehicle detecting device which performs vehicle detection by the method, can attain a miniaturization and can be used effective in management of parking vehicles using a vehicle detecting device of low power consumption, and this vehicle detecting device. MEANS [Means for solving problem]In a vehicle detecting method which according to this invention detects a magnetic field generated from vehicles with a magnetic sensor, and detects vehicles magnetically in order to solve above-mentioned SUBJECT, A magnetic sensor which put in order two or more magnetism detecting elements which have magnetic field detection sensitivity in the direction vertical to a ground surface along with a vehicles longitudinal direction is installed in a ground surface in a band pass of vehicles, or underground, External magnetic field intensity change as on the basis of the state where each of two or more of said magnetism detecting elements detects external magnetic field intensity, and there are no vehicles was measured, and a method of detecting vehicles by the judgment of whether total of an absolute value of two or more measurement values of this measuring result exceeds predetermined joint threshold S was adopted. [0013]According to such a vehicle detecting method, influence of a zero crossing point which magnetic field polarity looked at by distribution of magnetic field strength in a case of measuring a magnetic field generated from a vehicles pars basilaris ossis occipitalis reverses can be avoided, and highly precise and reliable vehicle detection can be performed. [0014]According to this invention, it is a vehicle detecting device which detects a magnetic field generated from vehicles with a magnetic sensor, and detects vehicles magnetically, A magnetic sensor which consists of two or more magnetism detecting elements arranged so that it may have magnetic field detection sensitivity in the direction vertical to a ground surface and may rank with a ground surface in a band pass of vehicles, or underground along with a vehicles longitudinal direction, A measurement means which measures each of external magnetic field intensity change as on the basis of the state where there are no vehicles to each magnetism
  • 26. detecting element, based on external magnetic field intensity detected by each of two or more of said magnetism detecting elements, Total of each absolute value of a measurement value of external magnetic field intensity change measured by this measurement means adopted composition of a vehicle detecting device which has a judging means which judges vehicle detection by whether predetermined joint threshold S is exceeded. [0015]While being able to perform reliable vehicle detection with high degree of accuracy with a vehicle detecting method of this invention according to such composition, the magnetic sensor can consist of small size which consists of plurality of a small magnetism detecting element constituted, for example using a magnetic impedance component as a magnetic sensor of low power consumption. [0016]It is a vehicle detection system which performs vehicle detection using a vehicle detecting device by above-mentioned this invention according to this invention, A judging means which judges whether whether vehicles advanced on a magnetic sensor, whether it stopped on a magnetic sensor based on a decided result of vehicle detection by a judging means of said vehicle detecting device, and on a magnetic sensor were left, Car presence information on a purport that vehicles have stopped on a magnetic sensor based on a decided result of this judging means, And it has an output means to which vehicles output **** information on a purport that on a magnetic sensor was left, and composition of a vehicle detection system which enabled it to manage parking vehicles with the output of said car presence information and **** information was adopted. [0017]According to such composition, an advantage of a vehicle detecting device of this invention can be enjoyed, exact car presence information and **** information can be outputted based on highly precise and reliable vehicle detection, and it can use effective in management of parking vehicles. [0018] [Mode for carrying out the invention]Hereafter, an embodiment of the invention is described with reference to figures. [0019][Embodiment of a vehicle detecting method] Drawing 1 - 3 explain the embodiment of the vehicle detecting method by this invention first. [0020]In this embodiment, as shown in drawing 1, to the ground surface
  • 27. 14 in the width which the vehicles (car) 10 pass, or underground. The magnetic sensor 12 which has arranged two or more magnetism detecting elements 11A, 11B, and 11C which have magnetic field detection sensitivity in the direction (Z direction) vertical to a ground surface so that it may stand in a line along with the longitudinal direction of the vehicles 10 is installed, and vehicle detection is performed. [0021]The external magnetic field intensity change as on the basis of the state where each magnetism detecting element of the magnetic sensor 12 detects external magnetic field intensity, and there are no vehicles 10 is measured, and total of the absolute value of two or more measured magnetic-field-strength change detects vehicles by the judgment of whether to exceed a predetermined joint threshold. [0022]This method was drawn from the following examining results. [0023]First, on the ground surface 14 in the width which the vehicles 10 pass as shown in drawing 2, The magnetic sensor 12 which comprised one magnetism detecting element which has magnetic field detection sensitivity in the Z direction which is a vertical direction to the ground surface 14 is arranged, the vehicles 10 were moved on the sensor 12, the magnetic sensor 12 detected external magnetic field intensity, external magnetic field intensity change was measured, and the situation of the change was investigated. The variation of external magnetic field intensity made the measurement value in the state where there are no vehicles 10 the initial value used as a standard, and displayed a changed part from it. The element using the magnetic impedance component mentioned later as a magnetic sensing device was used for the magnetism detecting element. Two or more vehicles performed the sampling. Four data measuring of a characteristic example is shown in drawing 2 (a) - (d) in it. [0024]Generally, magnetic field distribution of the cross direction of a bar magnet has a peak of reverse polarity at both ends of the bar magnet 16 like drawing 3, and has a tendency which carries out a zero cross in the center section. On the other hand, it can guess that the body of a car constitutes a roughly big bar magnet from a vehicles longitudinal direction from it being in agreement with how of data measuring of drawing 2 to lengthen the skirt near the both-ends peak of magnetic field distribution of drawing 3 by (c) and (d), especially, if it observes near the both ends of a magnetic field change. However, attitude of a peak has dispersion
  • 28. considerably by overall magnetic-field-strength distribution, and it does not become a beautiful form like a bar magnet because local magnetization exists by part each of a body pars basilaris ossis occipitalis. [0025]Since detection of vehicles will detect the magnetic field of a body center section if detection of parking vehicles is taken into consideration, for example, it observes the magnetic field of the center of the body by the width of the length of the half of the body shown in the range of H seal in a figure of each data measuring of drawing 2. It is because the movement speed of the difference in the length of each body and the body at the time of Measurement Division had dispersion that the length of H seal differs. [0026]Also when unevenness is looked at by magnetic-field-strength change within the limits of H seal of the data of four examples and a zero cross exists, the absolute value of a measurement value may go into the DETTO point on which it is less than threshold s, and one magnetism detecting element is not enough as it for vehicle detection at a certain thing. [0027]When threshold s of one magnetism detecting element considers the resolution of a magnetism detecting element, and S/N of a circuit, 0.05 gauss of a minimum is a limit, and considering that a maximum has about 0.1 gauss vehicles like drawing 2 (c) in the maximum of the magnetic field change by vehicles, it is difficult to set up exceeding 0.1 gauss. [0028]Then, two or more magnetism detecting elements are arranged along with a vehicles longitudinal direction, and if vehicle detection is carried out by whether either exceeds threshold s, detection probability will increase. [0029]However, in the case of the vehicles of drawing 2 (d), when four magnetism detecting elements have been arranged to each of the position corresponding to four points, a in a figure, b, c, and d, the measurement value by which element will also be less than 0.05 gauss. If such a case is taken into consideration, the device which raises detection probability further is required. [0030]Then, the absolute value of the measurement value of two or more magnetic-field-strength change which detected external magnetic field intensity by each of two or more magnetism detecting elements, and was
  • 29. measured is added, The value of the product which, on the other hand, hung said number (addition numbers of a measurement value) n of a magnetism detecting element of added square roots on threshold s at the time of detection by an independent magnetism detecting element is set up as joint threshold S, If vehicle detection is judged by whether total of the added result of said absolute value exceeds joint threshold S, it is detectable by high probabilities. [0031]A noise component serves as a mean square to addition of the output of each magnetism detecting element, and if it is considered as the noise component of the respectively same size, this will use that the product of the noise for one element and the square root of the addition numbers n serves as a noise at the time of combination, and will try to earn the whole S/N. [0032]For example, magnetic-field-strength change, a of the data measuring of the vehicles of drawing 2 (d), b, c, and d, of four points, It will be 0.03G-0.04G-0.02G-0.03G, and if threshold s of independent detection is set to 0.05G, when these are added, it will be 0.12G, and 0.05xroot4=0.1 gauss is set to joint threshold S, total of the added result of an output will exceed joint threshold S, and detection of it will be attained. [0033]Therefore, when the magnetic field component of a direction vertical to the ground surface of the magnetic field generated from vehicles is detected by two or more Magnetism detecting elementn and the magnetic-field-strength change by vehicles existence is measured, It turned out that it is suitable that the total adding each of the absolute value of magnetic-field-strength change measured based on the detection result of n magnetism detecting elements of a result performs vehicle detection by whether joint threshold S as independent threshold sxrootn is exceeded. [0034]By the way, since a magnetic-field-detection output may become near a zero cross with a certain element and total of the above-mentioned added result may become low when detecting as mentioned above by two or more magnetism detecting elements, the method explained below can also be chosen as a method of raising vehicle detection efficiency further. [0035]Arrange in descending each absolute value of the measurement value of the external magnetic field intensity change from the initial value
  • 30. which detected external magnetic field intensity by two or more magnetism detecting elements of the magnetic sensor mentioned above, and was measured, consider it as |deltaH(k) | (k= 1, 2, ordinal number of --), and Namely, this value, They are [ threshold s in the case of one magnetism detecting element, and ] the following expression about said addition numbers n.[0036] [Mathematical formula 2] [0037]It compares whether it is alike, it sets, substitutes one by one from k= 1, and the above-mentioned expression is satisfied, and when the above-mentioned expression is satisfied, it judges with having detected vehicles. [0038]According to this method, vehicle detection efficiency can be raised by adding the measurement value of two or more external magnetic field intensity change to descending one by one, and using for the judgment of vehicle detection. [0039]In above-mentioned explanation, the "ground surface of "underground" meaning the inside of those fields including all the fields that vehicles, such as a floor line in the building of not only the ground surface of the ground, and the road surface of a road and the ground surface of an outdoor parking lot but a multi-level car parking tower, run fields thru/or park" of 14 is natural. [0040][Embodiment of a vehicle detecting device] Next, the embodiment of a vehicle detecting device which enforces concretely the vehicle detecting method mentioned above, and performs vehicle detection is described. [0041]First, the magnetism detecting element of the magnetic sensor used for a vehicle detecting device is explained. Being required of this magnetism detecting element should be 10 or more milligauss in (1) magnetic field detection sensitivity. [0042](2) There is two or more dispersion [ little ] of the performance of an element for use. [0043](3) Considering ground surface installation, the height of an element
  • 31. should be several millimeters. [0044](4) The detector circuit of an element is excellent in a noise-proof and temperature characteristics, and be low power consumption. [0045]Although there is a flux gate type magnetism detecting element as what satisfies the conditions of (1), if it is going to raise detection sensitivity with this element, several 10 mm of the length of an element will be needed, and it will not be satisfied with it of the conditions of (3). [0046]Since it is easy to come out of dispersion in performance, a problem produces a flux gate type magnetism detecting element also on condition of (2). [0047]Then, the magnetism detecting element constituted using a magnetic impedance component is seemed that it is the optimal by it. [0048]The magnetic impedance component is indicated by JP,H7-181239,A and the element body as a magnetic body is constituted from an amorphous wire or these days by the magnetic thin film etc. If the high frequency current of an MHz band is impressed to this element body, according to a magnetic impedance effect, according to an external magnetic field, the impedance of an element body changes several 10%, and can detect an external magnetic field using this. [0049]The sensitivity of a magnetic impedance component has the sensitivity of a 10-5 gauss stand, and number milligauss is securable and it is satisfied also with the practical resolution in the case where it connects with the circuit of a magnetism detecting element of the conditions of (1). [0050]From there being little influence of a demagnetizing field, it is easy for the length of an element to be 5 mm or less, and the conditions of (3) are also cleared. [0051]About dispersion in performance, when supplied with an amorphous wire, since it is easy to control thickness, dispersion in the performance resulting from the outside dimension of the magnetic body of an element body is pressed down, and is satisfied with that there is little dispersion in the path of a wire, and a magnetic film of the conditions of (2). [0052]Although application was considered according to the contents reported at the society etc. about the magnetic field detection which uses the Colpitts oscillating circuit about the conditions of (4), there is a problem practically. [0053]For example, the application of the magnetic field sensor as an
  • 32. azimuth sensor is shown by the "amorphous wire MI Colpitts oscillation type micro magnetic sensor" announced at the 18th Maganetics Society of Japan academic lecture meeting (14pB-7). [0054]In the composition of this azimuth sensor, an amorphous wire is included in a Colpitts type oscillator, and since change of an external magnetic field turns into change of oscillation amplitude and it appears, an output is obtained through a detector circuit. While sending a direct current through the coil directly twisted around the wire of the element, applying a DC bias magnetic field and making it operate in the field where sensitivity is high, he is trying to know the polarity of the direction of north and south. [0055]However, in minute magnetic field detection, such as geomagnetism (about 0.3 gauss) by this method. Change of the output after a detector circuit is as small as several percent, and in order to treat absolute value change of oscillation amplitude as an output as it is, sufficient S/N is not obtained from it being easy to be influenced by change of power supply voltage, the temperature characteristics of an element, etc. by amplitude fluctuation, and it is unreliable. [0056]So, in this embodiment, the circuitry of the magnetism detecting element shown in drawing 4 was adopted. [0057]The circuitry of the magnetism detecting element shown in drawing 4 consists of a Colpitts oscillator, a detector circuit, and a comparator, the magnetic impedance component 1 mentioned above is included in the Colpitts oscillator, it direct-winds, or the magnetic impedance component 1 is approached, and the coil 2 for bias is formed. [0058]In this composition, AC bias current Ib is sent through the coil 2, and an about **1-**2 gauss AC bias magnetic field is impressed to the magnetic impedance component 1. As shown in (a), amplitude modulation of the oscillation output which appears like the after-mentioned by this at the A point in a figure of a Colpitts oscillator according to the intensity of the external magnetic field Hex for [ which is impressed to the magnetic impedance component 1 ] detection is carried out, The ripple waveform corresponding to the bias magnetic field which has the difference of elevation of the adjacent peak corresponding to the intensity of the external magnetic field Hex by detecting this in a detector circuit at a B point as shown in (b) is acquired, By carrying out a party rate with the
  • 33. comparison voltage Vref which crosses the voltage waveform of said ripple with a comparator, the Pulse-Density-Modulation output corresponding to the intensity of the external magnetic field Hex can be obtained at C point. [0059]The signal of AC bias current Ib carries out dividing of the clock from the microcomputer judgment part mentioned later, with a low pass filter, it may be made into a sine wave or the shape of a triangular wave, and it may throw it in, or may provide and throw in an oscillator individually. [0060]Next, the details of operation of the circuitry of the magnetism detecting element of drawing 4 mentioned above are explained. [0061]the characteristic of a magnetic impedance component is symmetrical with the direction of +- in several gauss to the external magnetic field Hex, as shown in drawing 5 -- a V character-like impedance change is shown in general. As shown in drawing 5 (a) as a principle of operation of the magnetic impedance component 1 of drawing 4, when there is no external magnetic field, an AC bias magnetic field is +. - It touches symmetrically, In change of impedance to it, an impedance change which the difference of elevation does not have in peaks on a ripple breaks out by a magnetic field twice the frequency of AC bias. [0062]Since an AC bias magnetic field and the unsymmetrical magnetic field which the external magnetic field superimposed will start the magnetic impedance component 1 like drawing 5 (b) there if an external magnetic field is impressed to the longitudinal direction of the magnetic impedance component 1, The impedance change (ripple waveform) from which the height of a peak differs by turns on an impedance change arises. [0063]The ripple waveform in an impedance change as showed the output after detection of drawing 4 (b) which appeared as amplitude modulation in the oscillation amplitude characteristic of the Colpitts oscillator as change of this impedance was shown in drawing 4 (a), and detected that oscillation output in the detector circuit by drawing 5 (b), and a similar signal are acquired. The size of an external magnetic field is changed into the output of a digital signal by which Pulse Density Modulation was carried out by carrying out a party rate with the comparison voltage Vref which crosses a ripple waveform as the signal is shown in drawing 6 in a comparator. That is, the Pulse-Density-Modulation output in which the pulse which is two kinds from which pulse width differs according to
  • 34. external magnetic field intensity appears by turns is obtained. [0064]Thus, pulse width [ of two kinds of pulses ] A which appears by turns, and B can be measured and evaluated using the timer counter of a microcomputer, and the digital data in which external magnetic field intensity is shown can be obtained by asking for the digital data of difference A-B of pulse width by an operation after that. Although the measurement data of pulse width to a actual external magnetic field is shown in drawing 7, in **0.5 gauss shows an almost linear change. The numerical input value of joint threshold S mentioned above can be decided by transposing the magnetic field strength of magnetism detecting element independent threshold s to the math-processing value of pulse width based on this data, and hanging the several n square root of a magnetism detecting element on it. [0065]And the digital data of difference A-B of the pulse width measured in the state where there are no vehicles, in detection of vehicles is memorized as data of the initial value of the external magnetic field intensity used as a standard, Then, the absolute value of the difference of difference A-B of pulse width and the initial value according to the measured external magnetic field intensity is calculated as data corresponding to the absolute value of intensity change of an external magnetic field, It can ask for total of the data of said absolute value called for by further two or more magnetism detecting elements, and the existence of vehicles can be judged by whether the figure exceeded the numerical value of joint threshold S. [0066]Next, drawing 8 explains the composition of the vehicle detecting device using the magnetism detecting element of drawing 4. [0067]Colpitts oscillator 3 incorporating the magnetic impedance component 1 which wound the coil 2 for bias which 12 is a magnetic sensor and was mentioned above in the composition of the vehicle detecting device shown in drawing 8, They are the marks 11A and 11B about the magnetism detecting element of drawing 4 which consists of the detector circuit 4 and the comparator 5. -- As shown in 11N, N pieces are provided and it is constituted. Magnetism detecting elements 11A and 11B -- 11N is arranged so that it may rank with the ground surface in the band pass of vehicles, or underground along with the longitudinal direction of vehicles as mentioned above, and each element can be giving magnetic
  • 35. field detection sensitivity in the direction vertical to a ground surface. [0068]18 is a microcomputer judgment part which comprises a microcomputer, analyzes a Pulse-Density-Modulation output of each magnetism detecting element of the magnetic sensor 12, and judges existence of vehicles. The microcomputer judgment part 18, Either the timer counter 20 which counts pulse width [ of the control section 19 which performs whole control and various data processing, and a Pulse- Density-Modulation output mentioned above ] A, and B or magnetism detecting elements 11A-11N are chosen. It consists of the selector 21 which inputs the output pulse into the timer counter 20 and the clock generator 22, the clock divider 23, the low pass filter 24, and the bias circuit (amplifier) 25. [0069]Dividing is carried out so that a clock signal which the clock generator 22 oscillates may become the range of 1 kHz - 100 kHz by the clock divider 23 in this composition, The low pass filter 24 and the bias circuit 25 let this signal by which dividing was carried out pass, a signal of AC bias current of a sine wave or the shape of a triangular wave is formed, and it is impressed by the coil 2 for bias which are each magnetism detecting elements 11A-11N of the magnetic sensor 12. A feed zone of this bias current may be provided in the magnetic sensor 12 side. [0070]Next, vehicle detection operation by composition of drawing 8 is explained. First, an initial value of external magnetic field intensity used as a standard for asking for external magnetic field intensity change in the state where there are no vehicles is measured. For this reason, with the magnetic sensor 12, a pulse signal which detected external magnetic field intensity by two or more magnetism detecting elements 11A-11N, and carried out Pulse Density Modulation is outputted as mentioned above, and it sends to the selector 21 of the microcomputer judgment part 18. [0071]With the command from the control section 19, the selector 21 chooses and sends two kinds of pulses A and B further mentioned above while it chooses the output pulse signal of two or more magnetism detecting elements 11A-11N which should be sent to the timer counter 20 one by one and sends it. [0072]In the timer counter 20, the pulse width of two kinds of said pulses A and B of two or more magnetism detecting elements sent one by one is counted and evaluated, and the data is sent to the control section 19.
  • 36. [0073]In the control section 19, difference A-B of the pulse width data of A pulse and B pulse evaluated with the timer counter 20 is computed for every magnetism detecting element, and the measured value of external magnetic field intensity is calculated. The measured data is recorded on memory storage, such as RAM26 in the control section 19, as initial value data used as a standard. [0074]Then, in order to detect vehicles, the detection and the Measurement Division of external magnetic field intensity by each magnetism detecting element are performed in the same procedure as the above, In the control section 19, it asks separately, absolute-value-izes by using the difference of said measurement data and initial value data as external magnetic field intensity change data, and asks for the total, and the existence of vehicles is judged by whether it is over predetermined joint threshold S which the total mentioned above. And in the case of the vehicle detection system mentioned later, car presence information etc. are taken out based on the result of said judgment. [0075]In order not to treat the amplitude of a Colpitts oscillator as an absolute value in the circuitry of the magnetism detecting element of drawing 4 as an advantage of the equipment of these above embodiments probably but to treat a changed part of amplitude, a low change of the frequency by change, temperature characteristics, etc. of power supply voltage can be disregarded. [0076]Since the detect output of the external magnetic field intensity in the magnetic sensor 12 is digitized-output-ized by the Pulse Density Modulation by a comparator, The magnetic sensor 12 and the microcomputer judgment part 18 connect two or more magnetic sensors 12 to the microcomputer judgment part 18, and can carry out common use of the microcomputer judgment part 18 to two or more magnetic sensors 12 while also being able to perform installation to isolate and obtaining the flexibility of installation. [0077]Since the whole equipment which constituted the magnetism detecting element very small, could constitute the magnetic sensor 12 small, and includes the microcomputer judgment part 18 can be made small, The burden of installation cost is small, and it is low power consumption, and since the prolonged energization use which was poor at conventional loop coil type equipment is possible, the use of vehicle
  • 37. detection is expandable. [0078][Embodiment of a vehicle detection system] Next, drawing 9 and drawing 10 explain the embodiment of the vehicle detection system for the parking-vehicles management in the motor pool using the vehicle detecting device of drawing 8 mentioned above. As for this vehicle detection system, it is needless to say that the portion of the magnetic sensor 12 is provided in the ground surface of a motor pool or underground at least, and it carries out of the vehicle detecting device of drawing 8. [0079]Drawing 9 is a block diagram showing the functional composition of the vehicle detection system of this embodiment. Composition of those other than magnetic sensor 12 is specifically realized in drawing 9 by the hardware and software of the microcomputer judgment part 18 of drawing 8. [0080]In drawing 9, it realizes from the control section 19 of drawing 8, the timer counter 20, and the selector 21, and the measurement means 27 measures the external magnetic field intensity change as on the basis of the state where there are no vehicles based on the detection result of the external magnetic field intensity by the magnetism detecting elements 11A-11N of the magnetic sensor 12 as mentioned above. This measurement means 27 has the initial value memory measure 28 which memorizes the value of the external magnetic field intensity detected by the magnetism detecting elements 11A-11N in the state where there are no vehicles as an initial value used as a standard, and measures external magnetic field intensity change on the basis of the initial value memorized to this memory measure 28. The memory measure 28 is specifically constituted as RAM26 of drawing 8. [0081]It realizes as a function of the control section 19, and the vehicle detection judging means 29 judges vehicle detection as mentioned above based on the measuring result of the measurement means 27. [0082]Penetration, a stop, and the **** judging means 30 are realized as a function of processing of Step S3 of below-mentioned drawing 10 by the control section 19, S6, and S9, Based on the decided result of the vehicle detection by the vehicle detection judging means 29. [ whether vehicles advanced into the motor pool, and ] It is judged whether on whether it advanced on the magnetic sensor 12 formed in the motor pool, whether
  • 38. whether whether it having stopped in the motor pool and a motor pool having been left and vehicles stopped on the magnetic sensor 12, and the magnetic sensor 12 was left. [0083]Car presence and the **** information output means 31 are realized as a function of Step S7 of drawing 10 by the control section 19, and processing of S10, Based on the decided result of penetration, a stop, and the **** judging means 30, vehicles have stopped at the motor pool, the car presence information on the purport that vehicles have stopped on the magnetic sensor 12, and vehicles left the motor pool, namely, vehicles output the **** information on the purport that on the magnetic sensor 12 was left. [0084]External magnetic field intensity is detected by the basis of such composition by the magnetism detecting elements 11A-11N of the magnetic sensor 12, The external magnetic field intensity change on the basis of the state where there are no vehicles by the measurement means 27 based on the detection result is measured, and the judgment of vehicle detection is performed by the vehicle detection judging means 29 based on the measuring result. And based on the decided result of vehicle detection, penetration of the vehicles in a motor pool, a stop, and **** are judged by the judging means 30, and car presence information thru/or **** information are outputted by the output means 31 based on the decided result. [0085]Next, drawing 10 explains the details of vehicle detection operation of this system. Drawing 10 is a flow chart which shows the procedure of the vehicle detection processing by the control section 19 of drawing 8 which realizes each means 27, 29, 30, and 31 of drawing 9. [0086]On vehicle detection processing and first in Step S1 of drawing 10 the control section 19, The external magnetic field intensity by each magnetism detecting element of the magnetic sensor 12 is made to detect as mentioned above in the state where there are no vehicles, It asks for the measurement data of the external magnetic field intensity of A-B mentioned above based on the detection result, this is set up as initial value data used as the standard which asks for external magnetic field intensity change, and it memorizes to the recording equipment of RAM26 grade. Since there are no vehicles into a motor pool at this time, the control section 19 checks **** information.
  • 39. [0087]Next, in order to judge penetration of the vehicles to the magnetic sensor 12 top formed in penetration of the vehicles into a motor pool, i.e., the ground surface of a motor pool, and underground, Detection and Measurement Division of the external magnetic field intensity from the vehicles by each magnetism detecting element are performed in the procedure mentioned above (Step S2), It judges with vehicles having advanced into the motor pool, when it absolute-value-ized in quest of the difference of each measurement data A-B and initial value data separately and the total was over predetermined joint threshold S, and when not having progressed and exceeded for the following procedure, it returns to Step S2 (Step S3). [0088]When vehicles enter in a motor pool even in a front procedure, can judge that, but. Since it thinks when passing without stopping then, after judging penetration of vehicles at Step S3, detection and Measurement Division of the external magnetic field intensity from the vehicles by each magnetism detecting element are performed again (step S4), and it compares with total of the absolute value of data A-B measured last time (Step S5). When this measurement value is changing from the last measurement value, it judges with vehicles moving in the inside of a motor pool, and returns to step S4. [0089]Since it will be either when vehicles stop in a motor pool or a passing car comes out out of a motor pool as it is if change of measured value is lost, In order to carry out that judgment which is the any, in quest of the difference of an initial value and measured-value-data A-B, it absolute-value-izes separately by all the magnetism detecting elements, It judges that the total is in the car presence state which vehicles have stopped in a motor pool when total exceeds joint threshold S as compared with the above-mentioned predetermined joint threshold S (that is, it has stopped on the magnetic sensor 12) (Step S6), and car presence information is taken out (Step S7). On the other hand, when total of the absolute value of aforementioned difference A-B is not over joint threshold S, it judges with the passing car having come out out of the motor pool as it is, and returns to Step S2. [0090]Next, detection of the magnetic field of the vehicles by each magnetism detecting element in order to detect **** of the parked vehicles, Measure (Step S8) and it absolute-value-izes in quest of the
  • 40. difference of measurement data A-B and the data of an initial value separately, When the total is over predetermined joint threshold S, vehicles are judged continuously to be under parking, It returns to Step S8, and when it repeated and is not over measurement, vehicles judge with having left the inside of a motor pool (that is, on the magnetic sensor 12 was left), take out **** information (Step S10), return to Step S2, and are again repeated from detection of penetration of vehicles. [0091]Thus, based on the detection result of the magnetic field from vehicles, a stop and **** can be judged during penetration of the vehicles in a motor pool, and movement, and car presence information and **** information can be outputted. And the advantage of the vehicle detecting device of this invention can be enjoyed, a stop and **** can be correctly judged during penetration of vehicles, and movement by highly precise and reliable vehicle detection, and exact car presence information and **** information can be outputted. Therefore, the vehicle detection system of this embodiment is effectively [ as management of parking vehicles / because of management of parking duration, the empty area display in a scale parking lot, vehicle guiding, etc. ] available. DESCRIPTION OF DRAWINGS [Brief Description of the Drawings] [Drawing 1]It is an explanatory view showing the arrangement and the direction of magnetic field detection over the vehicles of the magnetism detecting element of the magnetic sensor in the embodiment of the vehicle detecting method by this invention. [Drawing 2]They are the explanatory view and graph charts showing the situation of the external magnetic field intensity change by movement of the vehicles detected with the magnetic sensor which comprised one magnetism detecting element. [Drawing 3]They are the explanatory view and graph charts showing the magnetic field distribution of the cross direction of a bar magnet. [Drawing 4]It is a circuit diagram showing the circuitry of the magnetism detecting element of the magnetic sensor used for the embodiment of the vehicle detecting device by this invention. [Drawing 5]They are graph charts showing the impedance change by the
  • 41. AC bias magnetic field and external magnetic field of a magnetic impedance component in drawing 4. [Drawing 6]It is a wave form chart showing the bias current Ib in drawing 4, the after-detection output of a detector circuit, and a comparator output. [Drawing 7]They are graph charts showing the pulse width and the count number of a difference of the pulse which is two kinds from which the pulse width of the comparator output to an external magnetic field differs. [Drawing 8]It is a block diagram showing the composition of the embodiment of a vehicle detecting device. [Drawing 9]It is a block diagram showing the functional composition of the embodiment of the vehicle detection system by this invention. [Drawing 10]It is a flow chart figure showing the vehicle detection procedure in the vehicle detection system. [Explanations of letters or numerals] 1 A magnetic impedance component 2 The coil for bias 3 Colpitts oscillator 4 Detector circuit 5 Comparator 10 Vehicles 11A-11N Magnetism detecting element 12 Magnetic sensor 14 Ground surface 18 Microcomputer judgment part 19 Control section 20 Timer counter 21 Selector 22 Clock generator 23 Clock divider 24 Low pass filter 25 Bias circuit 26 RAM 27 The measurement means of external magnetic field intensity change 28 Initial value memory measure 29 Vehicle detection judging means
  • 42. 30 Penetration, a stop, and a **** judging means 31 Car presence and a **** information output means DRAWINGS [Drawing 1] [Drawing 2]
  • 43. [Drawing 7] [Drawing 3]
  • 44. [Drawing 5] [Drawing 4]
  • 45. [Drawing 6]
  • 46. [Drawing 8]
  • 47. [Drawing 9]
  • 48. [Drawing 10]