Overview

LCoS (Liquid Crystal on Silicon) is one of the newest microdisplay technologies with JVC’s HD-ILA and Sony’s SXRD being proprietary versions of LCoS technology. HD-ILA stands for HD Direct-Drive Image Light Amplifier and SXRD stands for Silicon X-tal Reflective Display.

LCoS is a hybrid of LCD and reflective technologies. LCoS uses liquid crystals like LCD technology does, but they are reflective instead of transmissive.

The illustration above shows light coming in from a projection lamp and then being filtered into red, green, and blue colors. There is a LCoS chip for each of the ideal colors. The 3 chips produce the high resolution picture image for each color, which is then reflected and combined into a single colored image. This final image goes through the projection lens and onto the screen.

Since LCoS is a reflection technology, higher contrast-ratio images are produced. Another benefit of LCoS technology is that all the controlling microelectronics for each pixel is located beneath the liquid crystals. This is in contrast to LCDs, which have the electronics to the side of the liquid crystals. The benefit of having the microelectronics below is that it significantly increases the fill factor and helps stop the “Screen Door Effect” problem.

Production Update

Upside

• Bright images
• Great contrast ratio
• Great colors
• Great picture quality
• No burn-in. Important if you watch a lot of 4:3 images or use a HTPC
• No “Screen Door Effect”

Downside

• Hard to manufacture LCOS chips – Low availability with few companies producing LCOS TV’s. This is why JVC and Sony came up with their own proprietary designs.
• Not the best blacks which leads to lack of shadow depth (most noticeably on JVC’s model, but not an issue with Sony’s SXRD)
• Motion blur artifacts are still visible similar to LCD technology. Motion blur is not an issue with Sony’s SXRD
• Average 6,000 hours of life for the user-replaceable lamp
• Expensive (especially Sony’s SXRD)
• Older single chip LCoS designs use color wheels and can have the “rainbow effect” (Not an issue with JVC’s HD-ILA and Sony’s SXRD).

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