COMING SOON: FLAT-PANEL TVS
Large LCD panels, light valve projectors

The bulky, power-hungry CRT display seems headed for near-certain obsolescence. Liquid-crystal displays, till recently too expensive for consumer TVs and too difficult to manufacture at large sizes, are now coming into their own. Liquid-crystal light valves, a related technology, are being developed for projection TVs.

Beating the CRT. Before liquid crystal technologies begin to displace CRTs in mass-market products, they must drop in price and grow in resolution. LCDs don’t have to be quite as cheap as CRTs — flat panels have advantages of size and weight — but they can’t be more than two or three times as expensive if they are to find use in computer markets. Even in the laptop PC market, where cost is not as important as size and power consumption, most buyers have shied away from the high prices.

The key to price cuts is yield. The more pixels in a display, the likelier that there will be defective cells, rendering the whole unit useless. However, larger displays need proportionally more pixels, or image resolution suffers. That, in turn, raises the problem of controlling individual pixels; due to the comparatively slow switching times of liquid crystals, line-oriented passive scan approaches quickly run out of steam.

Japanese efforts. One large-scale LCD project has been started under the aegis of Japan’s Ministry of International Trade and Industry (MITI). The shareholders, including Key Technology Center, Sharp, Hitachi, NEC, Casio and Asahi Glass, have pledged funding that totals 2.8 billion yen ($20 million). The project goal: a prototype full-color 40-inch display by the fall of 1993.

The current state of the art is nowhere near a 40-inch display. Ten-inch flat displays are only now moving into the mass-production stage. The largest color panel now made is Sharp’s 14-inch device, although Hoshiden has shown a prototype of a 15-inch unit.

Mobile applications. There’s nothing like a high-volume application to push technology along the learning curve. A number of Japanese firms are looking to automotive navigation systems, along with radio displays and engine meters.

But mobile systems have problems besides cost and resolution. Temperature sensitivity is a critical issue; a display would have to survive a range from 80˚C (176˚F) down to-40˚C (-40˚F), although the working range could probably be narrower. Vibration is also a problem.

Eliminating pixels. According to the June Popular Science, an American firm, Projectavision, has patented a way to boost resolution optically. First, its device superimposes the red, green and blue dots rather than placing them side by side as in conventional systems. Second, Projectavision puts a tiny lens in front of each pixel. The improvement is said to be “dramatic.”

Projectavision’s prototype, described as a medium-resolution LCD panel, is being built in Austin, TX, in partnership with Microelectronics and Computer Technology Corp.

- Peter Dyson