Everything You Need to Know About TV Technologies

LCD

After reviewing the rear-projection LCD, it’s time to see what the LCD flat-panel is all about. The technology contains sheets and cells of liquid crystal to be polarized by an active matrix of TFT (thin-film transistors). Two thin layers of glass substrate are held together by polarization. One of them has the interior coated by a polymer to hold several tiny cells filled with liquid crystal. A pixel is comprised of three cells – one red, one blue, and one green. When an electrical charge goes through the system, the crystals either block or let the light coming from the back, making the cells work like shutters of a photographic camera. The so-called “response time” of LCDs concerns the speed of this tiny liquid crystal shutter opening or closing. The higher the response time, the longer the cell blinks, and the longer it gets to portray a new image – so the last one appears as a ghost on the screen. A high response time incurs in this “ghosting effect.” There’s also the chance of the pixels getting defective just like in rear-projection LCD technology. The flat-panels don’t get as big as the plasma rivals – the biggest LCD TV is a 108 inches model from Sharp. According to NPD Group, LCDs accounted for 60% of total TV sales in 2007 in the United States.

Model example: Samsung LN46A550 (46” 1080p HDTV)

Strong points

• No burn-in susceptibility as it happens with plasma.
• Higher resolutions for a better price than the same high res plasma models.
• Low power consumption.
• Cooler running.
• Work well in brightly lit rooms.

Weak points

• Ghosting effect in high response time displays.
• Defective pixels.
• Poor black level.