Which TV is Best:
LCD, Plasma, DLP, LCoS or LCD Rear Projection?
LCoS Front or Rear Projection TV
Now that we've reviewed LCD and DLP, let's look at what might replace them both. LCoS is the latest technology to be introduced and while only a few TVs are using it now, that will change. LCoS stands for Liquid Crystal on Silicon and it can be found in both front and rear projection televisions.
LCoS can be thought of as a hybrid of LCD and DLP technologies. It uses liquid crystal like LCD systems and it uses reflective technology like the tiny mirrors in DLP. A liquid crystal layer sits on top of a pixelated, reflective mirror substrate. Beneath the substrate exists another layer containing individual transistors to activate each pixel. Light is projected at the reflective surface, but it must first pass through the LCD layer. When a pixel is activated, it polarizes and blocks the light from reaching the reflective surface. Light that is reflected is then magnified and focused onto the screen through a series of lenses.
One advantage of this over DLP is that there are no moving parts, no mirrors to get stuck. An important advantage over LCD is the lack of matrix lines between pixels. Because the control electronics are behind the pixels, the pixels can be placed together without any black space between them. This eliminates the "screen door" effect found on LCD screens and provides the smoothest, seamless image possible.
Another advantage of LCoS is that most TVs use a three chip design; one chip is dedicated to each color, red, green and blue. The three chip design results in excellent color saturation. This also means there is no problem with a "rainbow" effect resulting from a spinning color wheel as in DLP TVs. Also, like LCD, there are no issues with screen "burn-in". Currently LCoS chips are manufactured in 1280 x 720 (720p) and 1920 x 1080 (1080p) resolutions. In video projectors, most models are SXGA (1365 x 1024).
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