How LCD Rear-Projection TVs Work

Generating Images

LCD, as well as DLP and LCOS rear-projection TVs, are also referred to as "microdisplays" because they are much lighter and about 25 percent thinner than CRT rear-projection units. More mature than DLP and LCOS, LCD Rear-Projection technology is transmissive, in that light is shined through the image-forming element (liquid crystal display). In an LCD unit, an arc lamp focuses light through three LCDs, each approximately the size of a postage stamp.

Creating Pictures

As in LCD flat-panel TVs, the liquid crystal acts like a switch. When the liquid crystal switch is "off," the light is rotated 90 degrees and subsequently blocked. When the switch is "on," the polarized light passes straight through. The liquid crystal also acts as a dimmer, allowing a portion of the light to shine through in order to create shades of grey.

Creating Color

Light from the arc lamp is first split with special mirrors into its red, green and blue components and passes through three separate LCDs, which modulate the red, green and blue parts of the image. The three colored beams are then combined and projected onto the screen.