Input/Output Devices (I/O) devices
- keyboards
- pointing devices
- mouse-invented by Doug Englebart, Turing Award recipient.
Rollers are used to sense side-side or up-down movement.
- touch
pen-used in "palm top" computers. Pressure creates contact
between two layers of electrically conductive material to complete a
circuit. These are used in conjunction with handwriting recognition
software.
- light pen-a light cell in the pen tip senses light from the screen
- track ball-upside down mouse.
- touch screen-a touch interrupts an infrared light beam
- touch pad-an electronic grid under the pad senses your finger or
thumb.
- joystick-often used in games
- pointing stick/trackpoint-small device used on the keyboards of
laptops
- scanners-a bright light is directed across the page. Mirrors are used
to reflect the image to a CCD (charge coupled device). The CCD converts
the light to electrical current. The current is then converted to a
digital value.
- digital camera
- voice recognition
- OCR-optical character recognition/reader
- MICR-magnetic ink character recognition/reader
- OMR-optical mark recognition/reader
- bar codes-used in POS (point of sale) systems. 3 widths of bars and
spaces. A light beam is bounced off the bar code and the reflected beam
is measured. The UPC (universal product code is the most common. This is
used to encode a 10 digit number identifying a product number and
manufacturer.
- monitors
- CRT-cathode ray tude. 3 electron guns (red/green/blue) beams strike a
phosphur coating on the back of the screen causing it to light up.
Resolution is measured in pixels.
- LCD-liquid crystal display. Liquid crystals are trapped between layers
of glass. A voltage causes the crystals to become opaque. Active matrix
systems offer higher resolution (a transistor controls each crystal cell).
Gas plasma screens used neon gas instead of liquid crystals.
- laser printers-a laser is used to write an electrostatic charge on
paper. The charge causes toner to adhere to the paper. The toner is then
baked onto the paper.
- ink jet printers-A print head moves across the paper to write the
image. An electric charge is used to head a small bubble of ink that
expands and is forced through a small nozzle onto the paper.
Discussion
1) Adaptive Technologies for the disabled
2) How will we evolve in response to technology