Rear Screen Vs. Front Screen
Rear-projection systems are self contained, whereas front-projection systems use a separate screen several feet from the unit.
CRT-Based (The Original) The first rear-projection technologies used three CRT guns to create red, green and blue images, which were mixed together. In order to generate sufficient light, the tubes were large, but the depth of 50" units was still only about two feet. Since CRT-based units use traditional phosphor tubes, they easily provide variable resolutions, whereas newer microdisplay-based use a fixed pixel matrix just like plasma and LCD displays. However, the microdisplay-based units use tiny imaging panels and fit into much narrower cases.
LCD-Based Microdisplay (MicroLCD) Light is beamed through three tiny LCD "microdisplay" panels (one red, one green, one blue) that are approximately 1.5" diagonal. Each microdisplay is modulated with the pixel pattern for that particular color. The image is enlarged to the size of the screen by a set of lenses.
DLP and LCoS Microdisplays DLP (Digital Light Processing) and LCoS (Liquid Crystal over Silicon) systems reflect light from tiny panels. DLP rotates pixel-sized mirrors to reflect light. LCoS uses LCD microdisplay panels similar to the LCD-based units mentioned above, except after passing through the microdisplays, the light is reflected from a mirror to the lenses. To generate color, DLP units either use a single chip and color wheel or three chips, each with its own set of mirrors and color filter. LCoS units use three LCoS panels. For more details, see DLP and LCoS. Which Is Better? Visual display technologies are rather subjective. To your eye, one type may look superior to another. The only way to know is to play your favorite types of movies on as many different TVs as you can. Otherwise, all the specifications in the world are meaningless.
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