The form of the projector color is divided into DLP (mainly TI semiconductor support projector manufacturers), LCD (mostly Japanese), LCOS. Projector imaging principle is the first light, light source LED, white light, xenon lamp, etc.. In the DLP projector, the image is generated by DMD (Digital Micromirror Device) from black to white gray. DMD is arranged on the semiconductor chip by a micro lens (precision, micro mirror) composed of a matrix, each of the micro lens control of a pixel in the projection screen. The number of micro lenses is consistent with the resolution of the projection screen, 800 x 600, 1024 x 768, 1280 x 720 and 1920 x 1080 (HDTV) are some of the common dimensions. Under the control of the digital drive signal, the micro lens can rapidly change the angle, and once the corresponding signal is received, the micro lens can be tilted 10 degrees, so that the reflection direction of the incident light can be changed. The micro lens in the projection state is shown to be "open" and tilted +10 degrees with the digital signal; if the micro lens is in a non projective state, it is shown as "off" and tilted -10 degrees. At the same time, the incident light reflected by the "open" state is projected onto the screen by the projection lens, and the incident light reflected on the micro lens is absorbed by the light absorber. In essence, there are only two kinds of micro lens angle: "open" and "off"". The frequency of the micro lens in the switch between the two states is changeable, which makes the DMD reflected light shows black (micro lens is in the "off" position) and white (micro lenses in the "open" state) between the various gray. The DLP projector mainly uses two methods to produce color images. These two methods are used in the single chip DLP projector and the three DLP projectors. Single chip DLP projector installed inside a DMD chip, the color is produced by the installation of a color wheel between the light source and the DMD. The color wheel is usually divided into four regions: red, green and blue area areaarea and a to increase the brightness of the transparent area. Because the transparent area will weaken the saturation of the color, it may be disabled or omitted in some models. The DMD chip and the color wheel rotate synchronously, so that when the light source is located in front of the blue part of the color wheel in DMD, display blue screen part. Red and green are also very similar. Red, green, and blue images are projected at a very high speed in order, so that the observer can see the "full color" picture of the composition of the three. In early models, each displaying a frame, only one rotation of the color wheel. Later models, the color wheel according to the two to three times the rate of rotation of the frame, there are some types of the color regions on the color wheel repeated two times, which means that the RGB image sequence will be repeated six times in a frame. In fact, the black part of the DLP does not reflect the light, so that the black part can not go out from the projector. So there is no black light, only the black part of the light emitted from the projector.