a very informative ppt with cool animations....

1. Touch Screens, Printers,
Projectors And Sensors
BY: ZAEEM DANIYAL

2. CONTENTS:
•Input devices
•Outputdevices
•Touch-screens
•Sensors
•Printers
•Projectors
•Sources

3. Input devices:
o An input device for a computer allows you to enter information.
Input Devices:
Cameras
Trackballs
Barcode reader
Digital camera
Touch-screens
Keyboard
Microphone
Mouse (pointing device)
Scanner
Sensors
Touch-pens

4. Output devices are pieces of hardware that process data sent from a computer and
translate it into a form readable by humans.
Output Devices :
Monitors
Printers
Speakers
Plotters
Projectors
Computer output microfilm
Sound cards
Headphones

5. Touch-screen technology is the direct manipulation type gesture based technology. Direct
manipulation is the ability to manipulate digital world inside a screen without the use of
command-line-commands. A device which works on touch-screen technology is coined as
Touch-screen. A touch-screen is an electronic visual display capable of ‘detecting’ and
effectively ‘locating’ a touch over its display area. It is sensitive to the touch of a human
finger, hand, pointed finger nail and passive objects like stylus. Users can simply move
things on the screen, scroll them, make them bigger and many more.

6. TYPES:

7. A sensor is a device that detects and responds to some type of input from the
physical environment. The specific input could be light, heat, motion,
moisture, pressure, or any one of a great number of other environmental
phenomena. The output is generally a signal that is converted to human-
readable display at the sensor location or transmitted electronically over a
network for reading or further processing.

8. Here are a few examples of the many different types of sensors:
In a mercury-based glass thermometer, the input is temperature. The liquid
contained expands and contracts in response, causing the level to be higher or
lower on the marked gauge, which is human-readable.
An oxygen sensor in a car's emission control system detects the gasoline/oxygen
ratio, usually through a chemical reaction that generates a voltage. A computer in
the engine reads the voltage and, if the mixture is not optimal, re-adjusts the
balance.
Motion sensors in various systems including home security lights, automatic
doors and bathroom fixtures typically send out some type of energy, such
as microwaves, ultrasonic waves or light beams and detect when the flow of energy
is interrupted by something entering it’s path.
A photosensor detects the presence of visible light, infrared transmission (IR),
and/or ultra-violet (UV) energy.

9. Printer is a peripheral which makes a persistent human-readable
representation of graphics or text on paper or similar physical media.

10. There are many different types of printers. In terms of the technology utilized, printers fall into
the following categories:
• Daisy-wheel: Similar to a ball-head typewriter, this type of printer has a plastic or
metal wheel on which the shape of each character stands out in relief. A hammer presses
the wheel against a ribbon, which in turn makes an ink stain in the shape of the character
on the paper. Daisy-wheel printers produce letter-quality print but cannot print graphics.

11. Dot-matrix: Creates characters by striking pins against an ink ribbon. Each pin makes
a dot, and combinations of dots form characters and illustrations.

12. Laser: Uses the same technology as copy machines. Laser printers produce very high
quality text and graphics.

13. LCD & LED :Similar to a laser printer, but uses liquid crystals or light-emitting diodes
rather than a laser to produce an image on the drum.

14. Line printer: Contains a chain of characters or pins that print an entire line at one time.
Line printers are very fast, but produce low-quality print.

15. Thermal printer: An inexpensive printer that works by pushing heated pins against heat-
sensitive paper. Thermal printers are widely used in calculators and fax machines.

16. A projector is a device that uses light and lenses to take an image and project a magnified
image onto a larger screen or wall. Projectors can magnify still or moving images
depending on how they are built. The image must be shone through a sealed tube or
frame when passing through the lenses to maintain focus.
BENEFITS:
Still and video projectors are used by both business and educational institutions
to showcase important presentations and videos. Movie theaters to this day use
projectors to show films on a large screen.

17. 1) DLP Projection:
DLP technology is based on an optical semiconductor called a DMD chip
(Digital Micro-mirror Device), which was invented in 1987 by Texas Instruments
(can’t remember the guys name). The way it works is that a DMD chip is made
up of millions of 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 length 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, color is still to be added.
TYPES:

18. 2) LCD Projection:
LCD Projection is by far the cheaper method of getting great home cinema. LCD (liquid crystal
display) projectors contain three separate LCD glass panels, one for red, green, and blue
components of the image signal being transferred 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.

19. Sources:
•http://whatis.techtarget.com
•http://www.webopedia.com
•http://forums.afterdawn.com/threads
•www.techwalla.com
•www.engineersgarage.com
•en.lichess.org
•allaboutbasic.com
•www.reference.com
•www.techopedia.com
•www.igcseict.info
•study.com