RCA shows 50-inch liquid crystal on silicon HDTV display

LAS VEGAS — Thomson Multimedia has unveiled at the 2001 International Consumer Electronics Show a 50-inch wide liquid crystal on silicon (LCOS) HDTV display, a lighter and thinner rear-projection TV that uses reflective light valve technology.

Thomson's newly-developed HDTV uses Three-Five Systems Inc.'s microdisplay silicon imagers; ColorLink's optical prism; and Corning Inc.'s illumination and projection optics.

A team of 30-to-35 engineers at Thomson worked over the last 18 months on the entire system, collaborating closely with the company's three aforementioned technology partners.

Potential revolution

Noting that "DTV is our future," Michael O'Hara, senior vice president of Thomson Multimedia, said that the company's new line of LCOS display products "has the potential to revolutionize the television industry."

Featuring progressive 1,280 x 720 resolution, Thomson's 50-inch rear-projection TV offers "true HDTV resolution, a cabinet depth of only 18-inches, and weighs less than 100 lb.," said Tom Gospel, LCOS project manager for Thomson.

The 50-inch display, dubbed the RCA L50000, is designed to receive both over-the-air and satellite signals. Scheduled for commercial introduction this summer, the unit will be priced "between $6,000 to $8,000," O'Hara said.

High-definition details

Under the LCOS HDTV display architecture, white light is generated by an ultra-high pressure lamp, and is processed into a laser-like beam through a series of integration optics that uses an optical prism to separate the light into R, G and B components. The three light streams are then directed to three color-specific LCOS imagers. The reflected video components are then recombined within the same prism into a single video stream. Finally, this output is magnified by a precision optical lens system so that it presents the high-definition image on a flat, high-definition screen.

However, Thomson is by no means the first company to design high-resolution rear-projection TVs using reflective light valve technology. "It's been done by others. I believe that JVC, for one, is at least two years ahead in the game," said Rick Doherty of the Envisioneering Group.

David Hakala, vice president in charge of product development for Thomson Multimedia, called JVC "one of the key competitors" to his company's new LCOS display, and acknowledged that it is "similar" to JVC's proprietary reflective LCD projector device, which JVC calls the Direct Drive Image Light Amplifier (D-ILA). The main difference between the Thomson and JVC displays is that "JVC is using holographic optical elements to do color separation, while we are using three pieces of separate silicon imagers [by Three-Five Systems]," Hakala said.

JVC launched its 50-inch D-ILA rear-projection TV with holographic optical elements in Japan in the late fall of 1999.

At Thomson, Hakala said the company set up a special project team three years ago to search for new high-definition projection TV technologies. After examining a variety of vendors' solutions, the company decided to develop its own, he said.

Thomson's relationships with its key technology partners — ColorLink, Three-Five (Tempe, Ariz.) and Corning (Corning, N.Y.) — are not exclusive. "In order to meet with our objective of dropping the system cost, we've come to a conclusion that it's better for our partners to drive their technologies further among other companies so that they can get the component price down," said Hakala.

By using reflective light valve technology, both JVC and Thomson are looking for more brightness and higher resolution in their projection systems.

Different alignments

Most LCD projection systems available today are based on a transmissive LCD using horizontal liquid-crystal alignment. In contrast, JVC's D-ILA and Thomson's LCOS HDTV are based on a reflective LCD projector using a vertical liquid-crystal alignment. By principle, a reflective LCD projector is known for its ability to offer images at much higher brightness and higher resolution, while the vertically aligned liquid crystal makes possible a much faster response time and higher contrast.

According to O'Hara, Thomson's new LCOS HDTV boosts the black/white contrast to a ratio of 250:1.

Aside from JVC and Thomson, more than a few consumer electronics companies are believed to be working on reflective LCD projectors, including Sharp, Samsung and Pioneer.

Asked about the lifetime of LCOS HDTV's ultra high pressure lamp, Hakala said, "In theory, it's about 10,000 hours. Although we think it can last longer. Obviously, this system hasn't been around long enough to test that yet."

The RCA L50000 will feature a small door on back of the rear-projection TV so that consumers will be able to replace the lamp as necessary, Hakala said.

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