1. Computer Graphics Prof. Muhammad Saeed

2. Hardware (Display Technologies and Devices) III Hardware III Computer Graphics August 1, 20122

3. Display Devices and Technologies August 1, 2012 1.CRT (Cathode Ray Tube) 2.LCD, TFT LCD (Liquid Crystal Display, Thin Film Transistor LCD) 3.PLASMA 4.OLED (Organic Light-emitting Diode) 5.FED (Field Emissive Display) 6.SED (Surface-conduction Electron-emitter Display) 7.IMOD (Interferometric Modulator) 8.EL (Electroluminescent display) 9.Electronic Paper 10.Surface Technology 11.Wall Displays 12.Holographic Displays 13.3D Displays With and Without Glasses 14.No-Touch Displays (hand movements) Hardware III Computer Graphics 3

4. August 1, 2012 Basics of LCD Display Hardware III Computer Graphics 4

5. August 1, 2012 LCD Display Hardware III Computer Graphics 5

6. August 1, 2012 LCD Display & TFT Technology Hardware III Computer Graphics A TFT monitor uses thin-film transistor technology for the ultimate LCD display. The benefit of a TFT monitor is a separate, tiny transistor for each pixel on the display. Because each transistor is so small, the amount of charge needed to control it is also small. This allows for very fast re-drawing of the display, as the image is re-painted or refreshed several times per second. 6

7. August 1, 2012 Drawbacks of LCD Display Narrow viewing angle Fragile Fixed resolution and aspect ratio. Longer response time Lower contrast Cost is high Advantages of LCD: Less power consumption Small weight Less glare no flicker and bright Images not distorted Pros & Cons Hardware III Computer Graphics 7

8. August 1, 2012 Gas Plasma Discharge Principle Plasma Display Hardware III Computer Graphics 8

9. August 1, 2012 Inside the Display: Gas and Electrodes The xenon and neon gas in a plasma display is contained in hundreds of thousands of tiny cells positioned between two plates of glass. Long electrodes are also sandwiched between the glass plates, on both sides of the cells. The address electrodes sit behind the cells, along the rear glass plate. Plasma Display Hardware III Computer Graphics 9

10. August 1, 2012 The transparent display electrodes, which are surrounded by an insulating dielectric material and covered by a magnesium oxide protective layer, are mounted above the cell, along the front glass plate. Both sets of electrodes extend across the entire screen. The display electrodes are arranged in horizontal rows along the screen and the address electrodes are arranged in vertical columns. As you can see in the diagram below, the vertical and horizontal electrodes form a basic grid. To ionize the gas in a particular cell, the plasma display's computer charges the electrodes that intersect at that cell. It does this thousands of times in a small fraction of a second, charging each cell in turn. When the intersecting electrodes are charged (with a voltage difference between them), an electric current flows through the gas in the cell. As we saw in the last section, the current creates a rapid flow of charged particles, which stimulates the gas atoms to release ultraviolet photons. Hardware III Computer Graphics 10

11. August 1, 2012 Plasma Display Hardware III Computer Graphics 11

12. August 1, 2012 Phosphors: ZnS:Ag, Y3Al5O12:Ce, and Y2SiO5:Ce. ZnO, Cd:ZnS, Y2O2S:Eu The released ultraviolet photons interact with phosphor material coated on the inside wall of the cell. Phosphors are substances that give off light when they are exposed to other light. When an ultraviolet photon hits a phosphor atom in the cell, one of the phosphor's electrons jumps to a higher energy level and the atom heats up. When the electron falls back to its normal level, it releases energy in the form of a visible light photon. The phosphors in a plasma display give off colored light when they are excited. Every pixel is made up of three separate subpixel cells, each with different colored phosphors. One subpixel has a red light phosphor, one subpixel has a green light phosphor and one subpixel has a blue light phosphor. These colors blend together to create the overall color of the pixel. By varying the pulses of current flowing through the different cells, the control system can increase or decrease the intensity of each subpixel color to create hundreds of different combinations of red, green and blue. In this way, the control system can produce colors across the entire spectrum. Hardware III Computer Graphics 12

13. August 1, 2012 Drawbacks of Plasma: Phosphor burn-in (overdrive) Power consumption and heat dissipation Pixel pitch is coarse (.8mm - 1 mm) Advantages of Plasma: Wider viewing angles (160 degrees H&V) Saturated colors, lower gray levels Faster video switch times (full motion 60 Hz) Pros & Cons Hardware III Computer Graphics 13

14. End Hardware III August 1, 2012 Hardware III Computer Graphics 14