1. LCD TELEVISION By SHRUTHY CHANDRAN EC B S8 ROLL NO:34

2. OVERVIEW LCD technology History Components of LCD TV Working principle Properties Advantages Disadvantages Conclusion Reference

3. LCD TECHNOLOGY works by selective passage of light, which passes through millions of individual LCD shutters These shutters are arranged in grids and constitute colored filters, allowing only the RGB (red, green, blue) portion of the light to pass through white light is typically provided by a series of CCFLs (Cold Cathode Fluorescent Lamps), which are at the rear of a screen Every single sub-pixel is formed by a shutter-filter combination, and these sub-pixels blend together to form the whole picture

4. HISTORY The earliest commercially made LCD TV was the Casio TV-10 made in 1983 Sharp’s Magohiro Aramoto introduced the first wall hanging television product in 1991 Now many others (LG,HP,Samsung)are manufacturing LCD TVs

5. Components Of LCD TV Liquid crystals Cold Cathode Fluorescent Lamps (CCFLs) Polarizer plates In-Plane Switching displays (IPS and S-IPS) Electrodes made of a transparent conductor like indium tin oxide Thin film transistor (TFT)

6. WORKING PRINCIPLE It has two sheets of polarized glass plates with some liquid crystal solution trapped between them Forcing the liquid crystals into a twisted structural arrangement ARRANGEMENT TWISTED ARRANGEMENT OF CRYSTALS

7. When no voltage is applied, the liquid crystals would have a twisted structural arrangement. Also if light is applied at this condition Light travels through the spacing of the molecular arrangement. The light also twists as it passes through the twisted liquid crystals. Light bends 90 degrees as it follows the twist of the molecules.

8.  When voltage is applied: Liquid crystal molecules straighten out of their helix pattern Molecules rearrange themselves vertically (Along with the electric field) No twisting throughout the movement Forcing the liquid crystals into a straight structural arrangement  When voltage and light is applied: Twisted light passes straight through Light passes straight through along the arrangement of molecules Polarized light cannot pass through the lower (lower polarizer) Screen darkens

9. PROPERTIES …… The LCD televisions provide high on image resolution Crystal-clear displays distortion-free sound transmission They deliver high-end, and consistent performance Represent an exciting synthesis of design and technology

10. ADVANTAGES  Brighter with Higher Contrast Significantly brighter and feature higher contrasts than traditional CRT sets  Viewing Angles and Dot Pitch Flat-screen LCD television displays can have up to a 160° viewing angle, ie TV will look good when viewed from any point 80° in either direction from the center of the display  Smooth Bold Picture Quality It doesn’t have scan lines that conventional sets do. So each subpixel has its own transistor electrode, which creates smooth, evenly lit images across the entire surface of the display  The display is multi-functional and long-lived An LCD is a television monitor, capable of displaying HDTV, regular TV, and home video

11. DISADVANTAGES  Viewing Angle Color can distort when looking at an LCD from an angle, especially with older LCD monitors  Color Accuracy Because of the backlighting, pixels on an LCD are unable to generate light independent of the rest of the picture.  Prices LCD televisions are more expensive than other comparable TVs  Lower contrast ratio LCD televisions have poor contrast ratios. This is due to backlighting shining through the panel

12. CONCLUSION Liquid-crystal display televisions (LCD TV) are television sets that use LCD display technology to produce images LCD televisions are thinner and lighter than cathode ray tube (CRTs) of similar display size, and are available in much larger sizes When manufacturing costs fell, this combination of features made LCDs practical for television receivers.

13. REFERENCE LCD Principle http://infochem.hanyang.ac.kr/researches/researches_lcd_engli sh.html http://infochem.hanyang.ac.kr/researches/researches_lcd_engli sh.html Sharp http://www.sharp.ca/lcd_principles.html http://www.sharp.ca/lcd_principles.html Liquid Crystals http://www.ee.calpoly.edu/~dbraun/courses/lcd.html http://www.ee.calpoly.edu/~dbraun/courses/lcd.html