Light Years Ahead

My first brush with home theater was in a large, dedicated room equipped with a top-shelf cathode-ray-tube (CRT) front projector, a Faroudja video processor, a 100-inch (diagonal) screen, and a killer sound system. Subsequently, I've measured every home theater experience against that one, making me a tough customer to please.

While I continue to be a fan of CRT projectors, I'm also aware of their limitations. They provide the ultimate in image quality - including deep, solid blacks and razor-sharp details - but they're also bulky and expensive, and they need periodic maintenance. They also require an outboard processor to fill in the scan lines that become painfully visible when standard interlaced video is blown up to fill a really large screen. These shortcomings of CRT projectors have made me eager to see whether Digital Light Processing (DLP) technology, invented by Texas Instruments, can fulfill its promise to replace tubes in the projection-TV world. Judging from the wide assortment of DLP projectors now available, the new technology has made rapid progress. What's more, a number of the latest models are HDTV-ready.

At the heart of a DLP projector is a Digital Micromirror Device (DMD), a very high-tech integrated circuit with hundreds of thousands of tiny mirrors. The first DLP projectors used a DMD with a traditional squarish aspect ratio (4:3), but during the past year Texas Instruments has made a widescreen 16:9 DMD with a resolution of 1,280 x 720 pixels - an exact match for the 720p HDTV format - available to manufacturers.

To give you a better idea of what you're getting when you buy a DLP projector, and how it differs from a tube model, a brief explanation is in order. In a CRT projector, a tightly focused beam of electrons is fired at the phosphor-coated inner surface of the three tubes, one for each primary color (red, green, and blue). As the electrons strike the phosphor, they become energized and emit light to form images that get projected on the screen. A DLP projector generates images by beaming white light from a lamp at the tiny mirrors covering the surface of its DMD. Each mirror pivots up to 50,000 times a second between reflective and nonreflective states. The length of time a specific mirror reflects light determines where its corresponding pixel falls in the grayscale.

In single-chip DLP projectors - a category that includes most models on the market, including the three I compared for this test - color is added via a rotating wheel equipped with red, green, and blue filters. The wheel is placed between the lamp and the DMD, and its rotations are precisely timed to separate the light into red, green, and blue components. The filtered light is reflected in sequence off the DMD's surface and beamed through a lens toward the screen at such a rapid pace that the eye is tricked into seeing a full-color image. In early DLP designs, slight time lags between the red, green, and blue beams created occasional artifacts, but current designs appear to have solved the problem.

Our three DLP projectors - the SIM2 Sèleco HT300 ($14,995), the Sharp XV-Z9000U ($10,995), and Runco's VX-1000c ($16,995) - all feature the high-definition Texas Instruments chip. For my evaluations, I used an 80-inch-wide (92-inch diagonal) Stewart Filmscreen GrayHawk screen, a low-gain model designed to optimize contrast levels with DLP projectors. By the time the testing was finished, I had spent so many hours in the dark that I looked like Batboy from the cover of the Weekly World News, but that's a story for another time.

In The Lab


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