Basic information about Monitor

1. Monitor
1. Alternatively referred to as
a video display terminal (VDT) and video display unit
(VDU), amonitor encompasses a display screen for video
images and casing that holds it. In its most common usage,
monitor refers only to devices that contain no electronic
equipment other than what is essentially needed to display and
adjust the characteristics of an image.
Like most early TVs, the early computer monitor's were
comprised of a CRT (Cathode Ray Tube) and a fluorescent screen.
Today, all monitors are created using flat panel
display technology, like that shown in the image.
Why is a monitor an output device?
A monitor is only used to display (output) information from a
computer and provides no source of input. Because a typical
monitor sends no information back to the computer it is
an output device.
CRT

2. 1. Short for Cathode-Ray
Tube, a CRT is the electron beams within a monitor that move
across your screen either interlaced or non-interlaced hitting
phosphor dots on the inside glass tube. The picture is an
example of the inside of a computer monitor that shows the CRT
connected to the screen.
Within the CRT are three electron guns, red, green, and blue.
Each of these guns streams a steady flow of electrons, left to right,
for each line of your monitor. As the electrons hit the phosphors
on the CRT, the phosphor will glow certain intensities. As a new
line begins, the guns will then begin at the left and continue right;
these guns will repeat this process sometimes thousands of times
until the screen has been completely drawn line by line.
Once the phosphors on the CRT have been hit with an electron
they only glow for a short period of time; because of this, the CRT
must be refreshed, which means the process will be repeated as
explained above. If the video card's refresh rate is not set high
enough, you may encounter a flicker or a noticeable steady line
scrolling from the top to the bottom of your screen.
LCD

3. 1. Short
for Liquid-Crystal Display, LCD is a flat display technology
used in laptops, cell phones, calculators, digital cameras,
and flat screen displays. The LCD is made of two sheets of a
flexible polarizing material and a layer of liquid crystal solution
between the two. An LCD is available as an active
matrix,dual-scan, or passive-matrix display and are most
common with laptop computers, like the Dell laptop computer
shown in the picture.
An LCD does not refresh like a CRT monitor, instead, a picture is
created from electricity sent to a liquid crystal that untwists at the
rate of electricity applied, to create 64 shades.
CRT vs. LCD
There are two primary types of computer
monitors in use today: LCD monitors and CRT monitors. Over the last 5 to 7
years, LCD monitors have taken over as the predominant monitor to be used
with a computer. In this document we will cover the pros and cons of both
the CRT type displays and LCD or flat panel type displays. You'll quickly

4. discover that the LCD or flat panel displays pretty much sell themselves and
why they are the primary display used today.
Topic CRT LCD
Size Because of the CRT in a
CRT monitor the
physical size of these
displays is much larger
than an LCD and usually
awkward on small
desks.
LCD monitors are much
thinner than CRT
monitors, being only a few
inches in thickness (some
can be near 1 inch thick).
They can fit into smaller,
tighter spaces, whereas a
CRT monitor can't in most
cases.
Dead
pixels
Although a CRT can
have display issues
there is no such thing as
a dead pixel on a CRT
monitor. Many issues
can also be fixed
bydegaussing the
monitor.
LCD monitors can
encounter dead pixels,
which causes small black
or other colored dots in
the display.
Weight A CRT monitor can
weigh 40 pounds or
more depending on the
size of the monitor.
LCD monitors can be
pretty light, weighing as
little as 8 to 10 pounds.
Price Because of the
popularity of LCD
monitors the price of
most CRT monitors is
very cheap. You can
also usually pick up a
used CRT for next to
nothing.
LCD monitors are a newer
technology and have
more demand so will be
more expensive than a
CRT.
Viewable The frame around the LCD monitors have a

5. area glass screen of the
monitor causes the
viewable area of the
screen to be smaller
than an LCD.
slightly bigger viewable
area than a CRT monitor.
A 19" LCD monitor has a
diagonal screen size of
19" and a 19" CRT monitor
has a diagonal screens
size of about 18".
Picture Because of the older
technology most CRT
monitors will not have
as good as quality as
picture as most LCD
displays.
Depending on the quality
of the LCD monitor, the
picture quality can be
quite superb and
amazing, almost like
looking out a window.
Viewing
angle
Almost every CRT have
a better viewing angle
than many LCD
displays.
Not all LCD monitors can
be viewed at every angle,
which makes it difficult for
anyone who is not in front
of the monitor to see the
screen.
Glare Most monitors have a
glass screen, which can
cause much more glare
than an LCD.
An LCD monitor doesn't
have a glass screen,
virtually eliminating any
glare.
Burn If the same image is left
on a CRT for days the
image can burn into the
display causing a
permanent ghost image
to appear on the
screen.
Unlike a CRT an LCD
monitor does is not
affected by a burn in or
ghosting problem.
Flicker Some people can see
the flicker in a CRT
On an LCD monitor,
screen flicker is very

6. monitor, which is due in
part to the refresh
rate of the screen
refreshing the image.
minimal if noticeable at all
because of the higher
refresh rate.
Response The response on early
LCD monitors was not
as good as most
monitors at the time,
making games and
movies not as enjoyable
to play.
Any LCD made within the
last 5 years have no
refresh rate issues.
Making the display just as
enjoyable as CRT
monitors.
Power A 17" CRT monitor will
use as much as 80
watts, depending on the
age.
LCD monitors are very
energy efficient. A 19"
LCD monitor only uses
about 17 to 31 watts on
average.
Projector
Often no larger than a toaster and only weighing
a few pounds, a projector is an output device that can take images
generated by a computer and reproduce them on a large, flat (usually lightly
colored) surface. For example, projectors are used in meetings to help
ensure that all participants can view the information being presented. The
picture is that of a ViewSonic projector.
The 3 types of Projector explained: LCD, DLP, CRT
.
.
.

7. [bold]Opening Note:[/bold] When buying a home cinema projector, it is better
to go for a true 16:9 widescreen projector rather than a 4:3. This is because a
4:3 screen has a lot of pixel wastage projecting black lines top and bottom. If
you want an LCD home cinema, buy a Panasonic PTAE500. If you want a DLP
one, get an Optoma H56 (or H76 if you can afford it).
Four Main things to look for:
1). The type of projector - LCD, DLP, CRT
2). The Lumens output (brightness) of lamp - 800-1000 is good for LCD, DLP
at 1000 is good. Dont get it to high or colours will look poor, less than 1500 is
really needed for good colour reproduction.
3). The Resolution. For optimal picture make sure to get XGA or WXGA. A
cheaper method is VGA/SVGA, but if you canget XGA or higher you wont
regret the moeny spent.
4). A very key point is contrast ration. 300:1 and less is poor meaning blacks
look dark grey. 700:1 and higher is good giving darker blacks and whiter
whites (contrast is difference between these two). 1000:1 + is excellent.
[bold]DLP Projection[/bold]
DLP technology is based on an optical semiconductor called a DMD chip
(Digital Micromirror Device), which was invented in 1987 by Texas
Instruments (cant remember the guys name). The way it works is that a DMD
chip is made up of millions of tiny tiny mirrors, that can rotate at a 10 degrees
angle (12 degrees on better models). These mirrors are literally capable of
switching on and off thousands of times per second and are used to direct light
towards and away from a dedicated pixel space. The lenght of time a pixel is
on/off determines the level of gray seen in the pixel. Completely on is lightest
(white) and off is darkest (black), although neither are ever pure white or black.
The current DMD chips can produce 1024 shades of grey. However, colour is
still to be added.
DLP Projection: (note its an old image thus only 3 colour segments)
On a DMD chip, colour is added using a colour wheel. This is a wheel that
spins round anything from 150x per second to 250x and more. Most of the
cheaper models will be made up of a 4 segment colour wheel. This will be
Red/Green/Blue and usually a clear segment. As light is passed through a
point on the spinning colour wheel the mirrors switch in accordance to the
light. 4 segment colour wheels can produce an effect that is known as rainbow.
This is when the projector, in effect, struggles to change between all the
colours quick enough, and along a line, the viewer may see a rainbow affect

8. (See fig 1):
6 Segment colour wheels are not effected in this way as badly as 4 segment
colour wheels. Note that most viewers will not notice any rainbow affects, but
some may. 6 Segment Colour wheels tend to spin faster and are made up of 2
sets of Red/Green/Blue segments thus enabling faster changes between the
colours. Some projectors like the Marantz system (Absolutely amazing
projector) have 7 segment wheels with anextra dark green colour which can
give even greater contrast rations (3000:1+). This is achieved with the Texas
Instruments DMD HD2 chip, which is found in some more expensive
projectors. A new feature due out in 2004 sometime is the xHD3 technology.It
will take the single chip technology to even greater heights by adding a new
rear coating to the mirrors and eliminating more of the latent brightness when
in the off position. Another upcoming technology is called Sequential Color
Recapture (SCR) where DLP systems will replace the traditional color wheel
with essentially, a Spiral of "Archimedes" RGB color pattern. This new
technology has been mathematically projected to rival the current quality of
3-modulator DLP Cinema systems.
DLP is the future of Home Cinema Quality projection. However, due to the
high cost of manufacturing the chips, LCD and CRt are more viable options on
the cost front. The potential drawback of this single-chip DLP technology is
that in any given instant, the picture on the screen is not the total image, but is
instead rapidly alternating between images consisting of the individual red,
green, and blue colors. Thus the eye and the brain play the last critical role in
making single chip DLP projectors work, by combining or averaging or
integrating the picture, so that the viewer perceives the desired image and not
the rapidly flashing momentary components of the image.
A problem with DLP can also be light leakage around the mirrors ending up
with a halo effect on some scenes. This has been addressed with the new Dark
chip (DDR) which has a dark coating underneath the mirrors.
[bold]LCD Projection[/bold]
LCD Projection is by far the cheaper method of getting great home cinema. I
have a Panasonic PTAE500 myself which is great and highly recommended.
LCD (liquid crystal display) projectors contain three separate LCDglass panels,
one for red, green, and blue components of the image signal being transfered
to the projector. As the light passes through the LCD panels, individual pixels
can be opened to allow light to pass or closed to block the light. This activity
modulates the light and produces the image that is projected onto the screen.
Below is a diagram showing how it works:

9. LCD is generally more 'light efficient' than DLP meaning that a 850 Lumen
LCD projector (like my Panasonic) will produce a brighter image thanan 850
Lumen DLP projector. LCD tends to producemore saturated colours. However,
the colours being more saturated makes people perceive the projector to be
brighter overall, even though the DLP white may be brighter. LCD tends to
produce a sharper image. This can actually be a bit of a disadvantage forvideo,
where it makes the pixellation more obvious. However, on a good XGA model
you wont really notice it unless up close. To explain this more look at the
following image. LCD's havea low fill factorwhereas DLP has a high fill factor:
This can sometimes cause what is known as a chicken wire effect. Again this is
really not noticeable to most people unless viewing the screen up close. This is
sometimes referred to as Screen Door Effect (SDE). An example of this can be
seen below: Note the image is magnified a lot.

10. DLP projector technology is generally preferred for home cinema and
portablity. LCD projectors are generally better where colour reproduction is
critical. To be honest it is a personal choice and a financial constraint that
helps people make up there mind.聽
[bold]CRT Projection[/bold]
CRT- Cathode Ray Tube 聽
This is the largest and most experienced player. Many of you have probably
seen this kind of projector at a bar or in an auditorium ata school. CRT utilizes
three tubes, sometimes called "guns." The three colors combine or converge to
make your image. CRTs do not have a fixed number of pixels, making them
versatile machines capable of clear images from higher or lower resolution
sources. CRTs also require periodic 'calibration' by a trained professional,
which can mean additional expense for the end user down the road. These
projectors are generally used in fixed installations because of their size. CRTs
are typically not as bright as the other technologies, but the refined picture
quality of a properly calibrated CRT is tough to beat. Its worth noting that to
replace the Guns, it costs quite a bit of money (on average 拢 500 per gun).
[bold]Conclusion[/bold]
If you want the best money can buy,a three chip DLP projection is the best you
can get. At around 拢 20,000 for a Marantz system its expensive. Next best is
something like Marantz 7 Segment Colour DLP projector at around 拢 7,000.
Down from that you have the Optoma H76 and H56 DLP projector which in
my opinion are as good as anyone would want.
The slightly cheaper method would be the Pansonic LCD projector i have
already mentioned. There are a vast number of projectors out there. Be sure to
remember the four key points i made at the top of this post when looking for
your projector.

11. Plotter
A plotter is a computer hardware device much
like a printer that is used for printing vector graphics. Instead of toner,
plotters use a pen, pencil, marker, or another writing tool to draw multiple,
continuous lines onto paper rather than a series of dots like a traditional
printer. Though once widely used forcomputer-aided design, these devices
have more or less been phased out by wide-format printers. Plotters are
used to produce a hard copy of schematics and other similar applications.
Advantages of plotters
 Plotters can work on very large sheets of paper while
maintaining high resolution.
 They can print on a wide variety of flat materials including
plywood, aluminum, sheet steel, cardboard, and plastic.
 Plotters allow the same pattern to be drawn thousands of time
without any image degradation.
Disadvantages
 Plotters are quite large when compared to a traditional printer.
 Plotters are also much more expensive than a traditional
printer.

12. What is Pixel Definition – Pixel kya hota
hai
pixel in hindi
Pixel is short for “picture element”, using the common
abbreviation “pix” for “picture” and el for “element”| एक
pixel ककसी भी graphic इमेज मे एक छोटा सा point और tiny dot होता
है | Graphics monitors ककसी picture को display करने के लिए
display screen को बहुत सारे (thousands or millions) pixels मे
divide कर देता है ये सभी pixels, rows and column मे divide होते
है एवं ये आपस मे इतने पास होते है की आप देख कर इनको identity नह ं कर
सकते and देखने पर ये एक यूननट की जैसे (पपक्चर) ह द खते है |
हर pixel मे use होने वािे “number of bits” बताते है की ककतने colors
or gray shades display ककये जा सकते है For example, 8-bit color
mode मे, color monitor हर एक pixel के लिए 8 bits use करता है एवं
उसी की वजह से 2 to the 8th power (256) different colors or
gray shades display होते है | Color monitors मे हर pixel तीन
dots से लमिकर बनता है – a red, a blue, and a green one.
Display की quality तीन बातो पर बहुत ज्यादा depend करती है 1) उसके
resolution पर 2) ये ककतने pixel display कर सकता है 3) ककतने bits
pixel को represent करने मे काम आ रहे है |