LCoS

LCoS

(Liquid Crystal on Silicon) A technology used to make microdisplays for rear-projection TVs and head-mounted displays (HMDs). Each LCoS chip hosts a grayscale LCD shutter sandwiched between a cover glass and a mirror. The bottom of the cover glass is coated with indium tin oxide that holds a charge. When combined with the charges at the x-y location on the chip's matrix, it causes the liquid crystals to modulate the light for that pixel.

A Mirror Reflects Light Back
Typically used in sets of three (one each for red, green and blue), light is beamed onto the LCoS chip. For the pixels modulated to allow light to pass through, the light hits a mirror and is reflected back to a color filter. The output of the three color filters is combined and magnified to the size of the screen.

SXRD, D-ILA and HD-ILA
Silicon X-tal Reflective Display (SXRD) and Direct Drive Image Light Amplifier (D-ILA and HD-ILA) are proprietary LCoS technologies from Sony and JVC respectively. See rear-projection TV.

LCoS and DLP Microdisplays
LCoS and DLP (Digital Light Processing) both reflect light from tiny panels. LCoS uses LCD panels similar to LCD-based units, except light is reflected from a mirror behind the panel instead of passing all the way through to the lenses. DLP rotates pixel-sized mirrors to reflect light. To generate color, LCoS units use three LCoS panels. DLP units either use a single chip and color wheel or three chips, each with its own set of mirrors and color filter. For more details, see DLP.

LCoS Chips

Also known as "imagers" and "spatial light modulators," LCoS microdisplays are typically less than an inch square, and their pixel pitch is incredibly tiny; in the 8 to 20 micron range. The three LCoS chips from Aurora Systems on the left have a 1280x768 resolution and a 12 micron pixel pitch. The one on the right has a 1024x768 resolution. (Image courtesy of Aurora Systems, Inc., www.aurora-sys.com)