Dictionary of Computers - LCD projector

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A type of projector that uses a series of colour liquid-crystal display (LCD) panels through which a very bright light is shone. The images on the LCD screens are focused onto a screen using a lens and are controlled by a computer, either instead of, or alongside, a normal monitor.

The colour balance of an LCD projector can shift to the blue end of the spectrum and manufacturers often compensate for this. As a result, modern LCD projectors produce very steady, vivid images. The light source is typically 2–3 times brighter than a standard overhead projector or photographic slide projector as light has to pass through the image screens, which have about the same transparency as a church stained-glass window. The two most common lamp types are metal halide and ultra-high performance (UHP) lamps. With metal halide lamps, the bulb tends to diminish in quality over time, with a loss of brightness and shift in colour as the lamp ages. UHP lamps last longer and tend to retain their quality. They require less power for the equivalent amount of brightness, and therefore do not require as much cooling as metal halide lamps.

Digital light processing (DLP) projectors are an alternative to the LCD projector. They tend to be very bright and have become popular for smaller, lighter, ultra-portable applications. To produce a colour image, DLP projectors reflect a light through a rapidly spinning colour wheel. This can lead to a slight flickering of colour and sometimes to an unnatural colour appearance. They also become very hot when used and this can prove a problem for a portable projector.

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