DLP (Digital Light Processing) is a reflective display technology was developed by Texas Instruments and it uses an optical semiconductor (known as the Digital Micromirror Device, or DLP chip, )to manipulate light digitally. The DLP chip is probably the world's most sophisticated light switch. It contains a rectangular array of up to 2 million hinge-mounted microscopic mirrors; each of these micromirrors measures less than one-fifth the width of a human hair.

A DLP chip's micromirrors are mounted on tiny hinges that enable them to tilt either toward the light source in a DLP projection system (ON) or away from it (OFF)-creating a light or dark pixel on the projection surface.The bit-streamed image code entering the semiconductor directs each mirror to switch on and off up to several thousand times per second. When a mirror is switched on more frequently than off, it reflects a light gray pixel; a mirror that's switched off more frequently reflects a darker gray pixel.

In this way, the mirrors in a DLP projection system can reflect pixels in up to 1,024 shades of gray to convert the video or graphic signal entering the DLP chip into a highly detailed grayscale image.

At this point there are two system choices for bringing the grayscale image into full RGB colour which are really a question of price. Cheaper systems use a single chip & colour wheel, more expensive systems use the three chip system (corresponding to R, G & B.)

The white light generated by the lamp in a DLP projection system passes through a color wheel as it travels to the surface of the DLP chip. The color wheel filters the light into red, green, and blue, from which a single-chip DLP projection system can create at least 16.7 million colors. And the 3-chip system found in DLP Cinema projection systems is capable of producing no fewer than 35 trillion colors.

The on and off states of each micromirror are coordinated with these three basic building blocks of color. For example, a mirror responsible for projecting a purple pixel will only reflect red and blue light to the projection surface; our eyes then blend these rapidly alternating flashes to see the intended hue in a projected image.


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DLP systems have traditionally offered greater contrast ratios than LCD systems although the differential is now decreasing. For this reason they have been used in home cinema systems where the contrast ratio is of greater importance. One drawback of the DLP system is the "rainbow effect" which some viewers are particularly susceptable to. This is caused when the viewer is able to perceive the changing colours rather than the image melding into a true RGB image. The first generation of DLP projectors used a colour wheel rotating at 60Hz (3600 rpm), which has been imcreased by a later generation of units. Some viewers still report a rainbow effect.

For more info on DLP visit http://www.dlp.com from where most of the above information was obtained.