How LCOS Rear-Projection TVs Work

Generating Images

LCOS, as well as LCD and DLP rear-projection TVs, are also referred to as "microdisplays" because they are much lighter and about 25 percent thinner than CRT rear-projection units. LCOS (liquid crystal on silicon) is both similar to LCD TV technology and very different. Light emitted by the arc lamp in the LCOS display passes through polarizers, but the liquid crystal material is sealed to the surface of a reflective silicon chip such that the light reflects off of the LCD rather than passing through it.

Creating Pictures

Similar to 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 is reflected from the LCOS chip to the display. The liquid crystal also acts as a dimmer, allowing a portion of the light to be projected in order to create shades of grey. Unlike traditional LCDs, in LCOS displays the electronic drivers controlling the light regulating action of the liquid crystal are etched into the silicon. The integrated drivers allow for the pixels to be arranged tightly together, creating room for more pixels and, subsequently, higher resolution. You see the effect of higher resolution after light reflects off the silicon chip, is magnified and is projected as an image on the screen.

Creating Color

Using filters and mirrors, LCOS technology splits light into three colors (red, blue and green), creates a unique image from each color channel and then combines the three separate color images. The resulting combined image is magnified 70 to 100 times and projected onto the screen.