This week JVC announced it has developed an optical engine that allows a 60-inch RPTV to have a depth of only 10 inches - so slim, and also so light in weight - you can hang it on a wall! Will JVC’s bold intention to bring such sets to the US market next year make inroads in flat-panel sales? Several things are standing in the way.

John DiLoreto
Analyst and Editor
of Insight Media

A couple years ago InFocus introduced and ultra-slim 50-inch DLP unit that was only 7 inches deep. Like the JVC design, the engine relied on a concave mirror to spread the pixels widely on the nearby screen. The unit was quickly discontinued. We suspect the unit could not be manufactured at a price competitive with other RP units. Certainly the demand is there, as JVC seems to agree.

The JVC engine, named Slim HD-ILA, similarly employs a concave mirror to reflect the light beam in place of a conventional flat mirror. The configuration enables the engine to be made compact with a wide 138° projection angle, 1.5 times greater than conventional RP products.

Today, a flat panel direct view LCD or plasma - only 4 to 8 inches deep and wall mountable is everyone’s dream TV. Although heavy and energy-inefficient, these sets have captured the consumer imagination with crisp, bright images and a wide viewing angle that allows you to place the set almost anywhere. The one drawback of these sets is theyre not very affordable, especially in a size where you can actually see all of the content in the HD image.

Rear-projection (RP) TV manufacturers have been trying to bridge this gap for years. The latest conventional 60-inch RPTV sets are 14 to 16 inches deep, but much more affordable than flat panels: $3,000 vs. between $7,000 (plasma) and roughly $20,000 (LCD). The traditional RP sets are compromised not only by a bulkier design, but a narrower viewing angle and a less crisp, less uniform picture.

Will this bold step by JVC move us closer to affordable, slim, high-quality HDTV? Hopefully, but the laws of physics are working against getting the best of both worlds. What can the viewer expect to give up in image quality in this new design?

In my presentations on HDTV image quality I harp on the concept of modulation transfer function (MTF), a means of measuring the information capacity of an image. Rear-projection images pass through a gauntlet of stages that rob contrast from the finer detail, unlike direct-view images.

Contrast-robbing stages include the projection lens, the mirror, the cabinet and the screen. Ignore the irrelevant on/off screen contrast (often measured in the thousands). As the images get finer there is less and less contrast. If you end up with a pixel-to-pixel contrast of less than 10 - as you see here in an actual photo of on/off adjacent pixels - you no longer have a high-quality video image.

We hope the difficult issues of cabinet depth, cost and image quality get addressed - whether that takes better optical components, electronics or cabinet design - because it’s the picture quality vs. price that matters, just as much as thickness of the cabinet. JVC may still need to learn that lesson. InFocus already has.