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Home theater is one of the fastest growing areas in home entertainment. One of the important device to build a home theater is projector. It is crucial that you purchase a home theater projector that can offer you the quality that you will be satifactory to you with out breaking your wallet. A projector is an apparatus for presenting an enlarged image on a screen from a transparency such as a photographic slide or a film. In a motion picture projector, each frame is held stationary at an illuminated aperture for a brief period, and then advanced by an intermittent sprocket or reciprocating claw, the light being cut off by a rotating shutter during the movement. The sound track on the film is reproduced at a separate sound head where the film is moved continuously at a constant speed.There are two technologies of projector : LCD and DLP. Both LCD and DLP are used in projectors suitable for home theaters, but they work in quite different ways and produce slightly different results. LCD The LCD Projector usually contains three separate LCD glass panels – one each for the red, green, and blue components of the video signal. The LCD chip is transparent, and when a powerful light source is passed through it, each individual pixel transforms the light and projects the image or data through a lens onto the screen. LCD projectors produce more accurate, sharper image and produce brighter images using less power. Most of the ordinary and average LCD projector have a screen ratio of 4:3. LCD might also have a screen ratio of 16:9. Images are projected on to a super-large screen. However, LCD projectors also have some disadvantages, although as the technology improves these are becoming less and less relevant. The first of these is pixelation, or what’s known as the screen door effect. This means that sometimes you can see the individual pixels and it looks as though you are viewing the image through a ’screendoor.’ The second is that LCD doesn’t produce absolute black. DLP Digital Light Processing (DLP) is a technology developed by Texas Instruments. It works by projecting light from the projector’s lamp onto a DLP chip, made up of thousands of tiny mirrors. Each mirror represents a single pixel and directs the light projected onto it either into the lens path to turn the pixel on or away from it to turn it off. Most DLP projectors have only one chip, so in order to reproduce color, a color wheel consisting of red, green, blue and sometimes, white filters is used. The wheel spins between the lamp and the chip and changes the color of the light hitting the chip from red, to green, blue. Each mirror on the DLP chip tilts towards or away from the lens path depending on how much of a particular colour light is required for that pixel at any given instant. DLP projectors tend to be smaller and lighter, have better contrast. The disadvantage of DLP projectors is sometimes suffers from the ‘rainbow effect’ where the picture appears as a rainbow briefly noticeable when changing focus from one part of the screen to another. This does not appear in “3 chip” DLP projectors, but these tend to be very high end projectors in terms of price.

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