The light source for a DLP display device is an arc lamp. The arc lamp produces an almost pure white light, which helps in correct color reproduction. The light goes through a color wheel which spins at approx. 10,000 RPMs. A color wheel has many filters on it to change the color of the light going into the optical block. The colored light then goes through a light tunnel, it creates a evenly distributed block of light. The light then travels through some optics and hits the DLP chip (or digital micro mirror device) to light up the individual pixels on the screen. The picture is created by the combination of the duty cycle of the DLP chip and synchronization between the DLP chip and color wheel.
Can have large displays, this technology is also used in projectors. Some movie theatres use a DLP projector. The refresh rate is faster then any other TV technology (besides a laser TV). With a new lamp the picture quality will be as good as it was new.
The lamp needs to be replaced every 6,000 - 8,000 hours of use. It is bulky, most DLPs are about 1.5' deep. Some people might see artifacts in the picture. The lamp uses a cooling fan which can collect dust and it generates a small amount of noise. The lamp will slowly reduce in brightness.
If you have a DLP TV, I suggest you see our page about Lamps.