Transcript Touch Screen - webKami.com

Display Technologies
Color Graphics Adapter (CGA),
1981
four colors
320 * 200 pixels
Enhanced Graphics Adapter (EGA)
1984
16 colors
640 x 350 pixels
Video Graphics Array (VGA)
1987
256 colors
640 x 480
BY
Kamran
Yousaf
New Technology
Extended Graphics Array (XGA)
1990
65536 / true color (16.8 million colors)
800x600
Ultra Extended Graphics Array (UXGA)
Mid 90’s
16.8 million colors
1600x1200 pixels
Digital data
digital-to-analog converter (DAC)
VGA cable.
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Kamran
Yousaf
Monitors DVI
Digital Video Interface (DVI)
VGA technology digital-to-analog
Degradation occurs.
DVI keeps data in digital form.
Eliminating signal loss.
Fine Piucture
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Kamran
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Terminology
Dot Pitch
Distance between centers of two pixels
Resolution
No of pixels contained in a square inch
Multiple of X-axis, Y-axis and color depth
Refresh Rate
Time to draw a frame
Time to complete a pass
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Kamran
Yousaf
Color Depth
Bit-Depth - Number of Colors
1 - 2 (monochrome)
2 - 4(CGA)
4 - 16(EGA)
8 - 256(VGA)
16 - 65,536(High Color, XGA)
24 -16,777,216(True Color, SVGA)
32 -16,777,216(True Color + Alpha
Channel)
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Kamran
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LCD Method
Liquid crystal molecules
Electric charge
Untwist ->No light pass
Twisted ->Light
Darker
Electrode
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LCD - TFT
Active-matrix LCDs
Thin film transistors (TFT)
Switching transistors and capacitors.
Arranged in a matrix on a glass substrate.
Row is switched on
Charge is sent down the correct column
Capacitor at the designated pixel receives
a charge.
Capacitor holds the charge until the next
refresh
Untwist
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Laser Printer
Static electricity
"temporary glue."
Photoreceptor drum
photoconductive material
total positive charge
Printer shines a tiny laser beam across the
surface to discharge certain points.
laser "draws" the letters and images to be
printed
Electrostatic image.
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Ink Jet Printer
Small droplets of ink
Eextremely small (50 ~ 60 microns in
diameter)
Resolutions up to 1440x720 dots per
inch (dpi).
The dots can have different colors
combined together to create photoquality images.
BY
Kamran
Yousaf
Touch Screens
Input
Multiple types
Resistive
Capacitive
Surface acoustic wave
Output
Same as Monitor/LCD
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Kamran
Yousaf
Touch Screen - Resistive system
Glass Layer
Conductive and a resistive metallic layer.
Scratch-resistant layer
Electrical current
Two layers make contact in exact spot
Change in Electrical field
Change in the electrical field
Coordinates of the point of contact are
calculated
Driver translates the touch
Transmits 75% of light
BY
Kamran
Yousaf
Touch Screens – Capacitive system
Electricaly charged layer
Glass panel of the monitor.
Touch -> Charge transferred.
Charge on the capacitive layer
decreases.
Decrease is measured in circuits
located at each corner of the monitor.
Driver Translates it.
Transmits almost 90% of the light.
Clear picture.
BY
Kamran
Yousaf
Touch Screens - Surface acoustic
Surface acoustic wave system
Transducers (one receiving and one
sending)
Receiving transducer tell if the wave has
been disturbed
Also locate it
No metallic layers on the screen
Transmits 100% light throughput
Perfect image clarity.
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Kamran
Yousaf
Scanners
Flatbed scanners
desktop scanners
commonly used.
Sheet-fed scanners
document moves
scan head immobile
looks like a printer.
Handheld scanners
user moves the scanner
Drum scanners
publishing industry
detailed images.
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Parts of Scanner
Charge-coupled device (CCD) array
Mirrors
Scan head
Glass plate
Lamp
Lens
Cover
Filters
Stepper motor
Stabilizer bar
Belt
Power supply
Interface port (s)
Control circuitry
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Kamran
Yousaf
Scanner- Core Components
CCD
Array
most common
collection of tiny light-sensitive diodes
convert photons (light) into electrons
(electrical charge).
photosites.
brighter the light, greater the electrical charge
Photomultiplier tube (PMT).
mounted on a glass cylinder.
Sensor at the center of the cylinder
splits light into three beams.
light is changed into an electrical signal.
BY
Kamran
Yousaf
Scanner Method
A lamp(CCFL/ xenon) illuminates the
document.
mirrors, lens, filter and CCD array makes
scan head.
scan head is moved slowly
Belt
Stepper motor
Stabilizer bar
Most scanners 300x300 dpi
number of sensors in a single row (xdirection sampling rate) of the CCD
precision of the stepper motor (y-direction
sampling rate).
BY
Kamran
Yousaf