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Digital Light Processing (DLP)

With the recent incredible increase in demand for home theater systems with ever greater resolutions it seems that new advances come about every time you read a technical magazine. One of the hot new technologies is Digital Light Processing or DLP for short. For any television system you need to create and control a series of points of light in red, green and blue. Combined they form the moving picture we all love to view. With DLP the integration of computer chips and television are raised to new heights.

A DLP system relies on Digital Micromirror Device, or DMD chip, which was invented by Dr. Larry Hornbeck of Texas Instruments in 1987. This is a computer chip with literally millions of tiny mirrors on it, each one independently oriented by the circuits on the chip. Typically, there are some 1.3 million mirrors on the chip, each one mounted on a hinge. The size of these mirrors is a miracle of precision, measuring only on fifth the width of human hair! The chip transforms a signal from a video source into directions to these mirrors, turning the mirror so that it either reflects the light or ignores it, turning the mirror towards the light source or away from it. This builds up a picture of fantastic resolution.

DLP can process some 1,024 shades of grey and 16.7 million colors in the typical home system or up to 35 million on high end professional models. The white light from the projector bulb is first passed through a spinning color wheel with pure red, blue and green on it. By coordinating the mirrors and the position of the color wheel vivid colors are perceived by the viewer.

You can either get a one chip or three chip variation of the DLP system. With one chip models usually found in the home systems the duration of each colored pixel, or the absence of them, creates the image. With the high end, professional three chip systems a prism is used instead of the color wheel to separate the white light into its component red, green and blue.

While almost everyone will be blown away with the clarity of the picture there is one down side. As with any projection television system there is a projector bulb. Now this is now the G.E. 100 watt bulb you can get in any store, it is a highly specialized bulb that can cost hundreds of dollars. Typically they last about 3,000 hours of use which for a hard core watcher will be about four to six years.

The sets are usually in the 30 to 50 inch range and can cost about $5,000.

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