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LCD vs DLP

Digital projectors are sometimes referred to as LCD projectors though they are not actually using LCD technology. The two main types of machines for projecting computer images onto a screen are LCD projectors and DLP projectors. The differences in these technologies are important to recognize when comparing similarly priced models.

LCD projectors operate by shining light through transparent liquid crystal display cells. In older thin film transistor, TFT, displays transistors controlled each cell. This changed their polarity to produce the appropriate color.

More common and more advanced are polysilicon LCDs, which use three separate color panels (red, green, and blue) to produce the desired color. The combinations of light shining through the LCD cells produce the desired image in both types of projectors.

DLP, Digital Light Processing, was developed by Texas Instruments in 1996. The DLP models project images by reflecting light to hundreds of tiny mirrors known as digital micro mirror devices, DMD. Each of the mirrors represent one pixel, this is individually powered by electronics in the projector that adjust the angle of the mirror according to the color being displayed. DLP are leading the weight loss trend in the projector market, this makes them appealing for presentations. You will also find that DLP projectors handle video images extremely well.
There is a third light engine technology called LCOS (liquid crystal on silicon). It's being developed by several vendors, including JVC, Sony, and Hitachi. Several home theater projectors have been manufactured with this technology.