DLP stands for Digital Light Processing, a unique projection technology developed by Texas Instruments and based around a proprietary semiconductor called a Digital Micromirror Device (DMD). A single high-intensity light source is reflected off the DMD, which modulates the light by rapidly manipulating the angles of hundreds of thousands of tiny mirrors on its surface. On its way to the DMD, the light passes through a rapidly spinning color wheel that alternately filters it into red, green, blue and sometimes white or yellow spectra. By temporally coordinating the mirrors' modulations with the sequence of colors passed through the color wheel, the DLP light engine can create images with very subtle color variations, which are then magnified and projected onto a screen. DLP rear-projection TVs come in screen sizes of approximately 42" and up; DLP technology also powers many front-projectors for both home theater and office applications.
Learn more about DLP projection technology in this informative Flash presentation.
More expensive than CRT projection systems but less costly than LCD or plasma, DLP rear-projection sets deliver excellent picture quality in a chassis that's significantly sleeker than that of a traditional projection TV. The DLP light engine is capable of very high brightness (though not as bright as LCD), so a DLP set can be viewed even in bright room conditions. The distance between the pixels on a DLP display is quite small, minimizing the "screen-door effect" (seen more prominently in LCD displays) to create a full, seamless image. Because of DLP's fine reproduction of blacks, its contrast performance is superior to any other non-CRT projection technology. The single-light-source design eliminates the convergence issues that plague CRT and some other projection systems, and limits maintenance costs (a single bulb to replace, for example).
DLP is not as bright as LCD technology, nor as compact as LCD or plasma flat-panel models (though the typical DLP rear-projection set is much shallower than most CRT-based rear-projection systems). Additionally, certain especially sensitive viewers notice an artifact commonly referred to as the "rainbow effect," a consequence of DLP's temporal approach to color formulation. Those viewers may momentarily see the light split into its component color spectra as their eyes travel quickly from one part of the screen to another — particularly when seated close to the screen. The unlucky few will likely find this quite distracting; fortunately, most viewers won't even perceive a problem. The latest-model DLP sets incorporate improved color-wheel technology in an effort to further minimize this artifact.
The bottom line
DLP rear-projection TVs offer several advantages over CRT rear-projection systems, for a modestly higher price — along with video performance that's superior in some ways to more expensive flat-panel displays. Their impressive price-to-value ratio makes them well worth considering if you're not fixated on a wall-mountable TV.