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VIDEO DISPLAY DEVICES Presentation Transcript
1. VIDEO DISPLAY DEVICES
2. Contents
3. CRT MONITOR cathode-ray tube
4. What is CRT
• Stands for “Cathode Ray Tube.”
• CRT is the technology used in traditional computer monitors and televisions
• The image on a CRT display is created by firing electrons from the back of the tube to phosphors located screen.
5. History of CRT
• The first CRT scanning device was invented by the German scientist K. F.Braun in 1897.
• Mr. Braun introduced a CRT with a flurescent screen,known as the cathode ray oscillo-scope.
• In 1907,the Russian scientist Boris Rosing used a CRT in the receiver of a TV system.
6. How CRTs work & display? A CRT monitor contains millions of tiny red, green, and blue phosphor dots.
7. How CRTs work & display? In a CRT monitor tube, the cathode is a heated filament. The heated filament is in a vacuum created inside a glass tube. The electrons are negative and the screen gives a positive charge so the screen glows.
8. Advantages of CRT
• A CRT can easily increase the monitor’s brightness by reflecting the light.
• It produce more colours.
• The CRT monitors have lower price rate.
• The quality of the image is superior than others.
• The contrast features are highly excellent.
9. Disadvantages of CRT
• It have a big back and It take-up space on desk.
• Constant refreshing of CRT monitors can resulting headache.
• CRTs are operating at very high voltage.
• These are heavy to pick-up and carry around.
10. LCD Liquid Crystal Display
11. What is LCD?
• Stand for liquid crystal display, a type of display used in digital watches and many portable computers.
• LCD displays utilize two sheets of polarizing material with a liquid crystal solution between them.
• An electric current passed through the liquid crystal. • Each crystal is like a shutter, either allowing light to pass through or blocking the light
12. What is TFT-LCD? TFT LCD (Thin Film Transistor Liquid Crystal Display) • TFT Glass has displayed number of pixels.
• A Color Filter Glass has a color filter which generates color.
• Liquid crystals move according to the difference in voltage between the Color Filter Glass and the TFT Glass.
13. History of TFT
• A thin film field-effect transistor was presented as early as 1935.
• The first functional thin film transistor was presented by P.K.Weimer.
• It is composed of a micro crystal line cadmium sulfide(Cds) semiconductor layer.
14. How does it work & display
• LCDs work by the tiny pixels on the screen showing more than 2,00,00,000 colours.
• A fluorescent light source, known as the backlight. This light passes through the first of two polarizing filters.
• The polarized light then passes through a layer called cells.
• The cells are arrayed in rows across the screen.
• one or more cells make up one pixel.
• Electric leads create an electric field that twists the crystal molecule, which lines the light up with the second polarizing filter and allows it to pass through it.
15. Advantages of LCD
• The sharpness of a LCD display is at maximum tweakness.
• High peak intensity produces very bright images.
• Screens are perfectly flat.
• Thin, with a small footprint. Consume little electricity and produce little heat.
• The LCD display unit is very light and can be put anywhere or moved anywhere in the house.
16. Disadvantages of LCD
• After a while the LCD display the some of the pixels will die you will see a discoloured spot on a black spot on the display.
• The cost of a LCD is considerably at a high price.
• The LCD display will have slow response times.
• The LCD display has a fixed resolution display and cannot be changed.
17. Plasma TV
18. What is Plasma?
• Plasma is often called the "Fourth State of Matter", the other three being solid, liquid and gas.
• A plasma is containing a significant number of electrically charged particles, a number sufficient to affect its electrical properties and behavior.
19. History of plasma tv
• First prototype for a plasma display monitor was invented in july,1964 by professors Donald bitzer and Gane slattow.
• The team had built the first plasma display panel with one single cell.Today’s plasma television use millions cell.
20. How does it work & display
• The TV lights up thousands of tiny dots with a high-energy beam of electrons.
• There are three pixel colours -- red, green and blue which are evenly distributed on the screen.
• By combining these colours in different proportions, the TV can produce the entire colour spectrum.
• The phosphors on the screen of the plasma enhances the viewing pleasure.
21. Advantages of plasma
• Larger viewing angle, 160º compared to LCD 40º & rear projection 120º.
• No projection throw distance limitations.
• All plasma display units are thinner in width than the CRT monitors.
• The plasma display units has a clearer image, brighter viewing angle, better colour quality and higher contrast ratio than the CRT and LCD display units.
22. Disadvantages of plasma
• Compared to other display units the plasma display unit has a very short life span.
• As your plasma display unit gets older,its brightness gets dimmer.
• Plasma display units are compareably more expensive than CRT monitors.
• Plasma display units must be handled carefully.
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