Display Technologies Color Graphics Adapter CGA 1981 four

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) 800 x 600 Ultra Extended Graphics Array (UXGA) Mid 90’s 16. 8 million colors 1600 x 1200 pixels Digital data digital-to-analog converter (DAC) VGA cable. BY 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 BY Kamran Yousaf

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 BY 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) BY Kamran Yousaf

LCD Method Liquid crystal molecules Electric charge Untwist ->No light pass Twisted ->Light Darker Electrode BY Kamran Yousaf

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 BY Kamran Yousaf

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. BY Kamran Yousaf

Ink Jet Printer Small droplets of ink Eextremely small (50 ~ 60 microns in diameter) Resolutions up to 1440 x 720 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 BY 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 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. BY 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. BY Kamran Yousaf

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 BY 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 is moved slowly Belt Stepper motor Stabilizer bar Most scanners 300 x 300 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