Micromirrors Project Better Images

Dave Andrews

Usually mirrors reflect an image, but a new technology five years in development at Texas Instruments (Dallas, TX) uses mirrors to create an image. The result of TI's Digital Light Processing (DLP) subsystem--now appearing in new PC projection systems--is bright, crisp output that's also visible from side viewing angles. And perhaps by this time next year, TI will have similar subsystems for high-quality color printers. The DLP technology is being used by In Focus Systems (Wilsonville, OR, 503-685-8888), Proxima (San Diego, CA, 619-457-5500), Nview (Newport News, VA, 804-873-1354), and other makers of projection devices for personal computers.

TI's DLP subsystem is based on the company's Digital Micromirror Device, a microchip upon which thousands of tiny aluminum microm irrors that rest on miniature hinges flutter on and off hundreds of times a second. The micromirrors' ability to turn on and off at lightning speed, when used in conjunction with a light source, optics, a revolving color wheel, and projection lens ( as shown in the illustrations ), creates projected images that are easily visible even in a room that's fairly well lit.

A fundamental advantage of the technology is that unlike LCD technology, in which light must pass through the screen, digital mirrors create images by reflecting light, which results in a brighter image. With digital mirrors, and unlike LCDs, brightness increases as resolution increases. "With LCD technology, increasing your resolution requires bigger light sources to maintain the same level of brightness," says Ken Knepper, senior product line manager at In Focus Systems, which was expected to release in June the LitePro 620, an SVGA projector featuring TI's DLP subsystem. The LitePro 620 (weighs 21 pounds and sells for about $10,000) delivers 450 ANSI lumens (a measure of brightness), compared to 350 lumens for the LitePro 610 VGA projector that also uses digital mirrors. In Focus's LitePro 210, which does not use digital mirrors, delivers 250 lumens. Both use a 270-W lamp.

TI says that later this year it will release DLP subsystems for projector manufacturers that incorporate higher resolutions of 1024 by 720 and 1280 by 1024 pixels. The company is planning two- and three-chip systems that offer brighter images and more vivid colors.

Other uses for digital mirrors include projectors for large venues like concert theaters and home theaters, plus desktop monitors. If TI delivers on its expectations, you'll be seeing mirrors in a lot of places besides your bedroom.

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How TI's Digital Mirror Subsystem Works

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