At the heart of the UHA technology is a hybrid scheme that combines a modified amorphous-silicon active matrix of thin-film transistors (TFTs) with low-temperature polysilicon drivers. Such a scheme was first discussed a number of years ago by dpiX (Palo Alto, Calif.).

While conventional amorphous-silicon LCDs use discrete driver chips that must be bonded to the display glass, low-temperature polysilicon drivers can be built directly on the glass using semiconductor-like processes. The ability to integrate drivers is said to result in a far simpler interconnect than that required for conventional LCDs.

Sharp reports that it has achieved roughly the same resolution — around 200 pixels/inch — as for full-out low-temperature polysilicon LCDs from Toshiba Corp., which currently has the low-temperature polysilicon LCD market more or less to itself.

Over the last year or so, Toshiba has been phasing in poly LCDs in sizes from 4 to 15 inches on the diagonal. Sharp's poly play, in contrast, is aimed immediately at large display applications requiring very large pixel counts, although a 6.4-inch model targets mobile Internet appliances.

The combination of amorphous-silicon TFTs and polysilicon drivers will help Sharp differentiate itself from competitors. A pure low-temp poly play was considered too difficult to achieve at this point, according to Masaya Hijikigawa, a corporate executive director of Sharp who heads up Sharp's LCD business.

IBM Japan and NEC have both announced prototypes of amorphous-silicon LCDs with 200-pixel/inch resolution but have not yet made them available on the market.

Bright display

The pixel aperture of UHA technology is about 20 percent larger than in Sharp's previous active-matrix silicon LCDs, according to the company. One result is that for comparable brightness, the new LCD's power dissipation will be about 20 percent lower. Alternatively, the display will be able to crank out higher brightness than a conventional LCD at the same power level.

The new pixel structure of the UHA technology also uses aluminum for both the source and gate lines to minimize wiring space and maximize aperture.

Sharp has developed UHA prototypes of both a 28-inch and a 6.4-inch LCD. The 28-inch display features a 2,560 x 2048-pixel quadruple-SXGA format, 116-pixel/inch resolution and 180-nit brightness, and it consumes 72 watts. The 6.4-inch display, in a 1,024 x 768-pixel XGA format with 202-pixel/inch resolution, provides a 62 percent aperture ratio, according to Sharp. The smaller display will be offered in both backlit and reflective versions for mobile Internet appliances. Production will begin next spring.

A recent report by IDC Japan Ltd. predicted that the second quarter of this year would be the first in which total Japanese supplies of large active-matrix displays would be surpassed by the total for South Korea and Taiwan combined. Sharp was once the top LCD supplier but now ranks fourth based on monthly capacity, behind the alliance of DTI, ADT and Hannstar; Samsung; and the alliance of LG and Philips-Hoshiden, according to IDC Japan.

In a bid to regain the top position, Sharp earlier announced a Fab 2 plan for its Mie works in Taki, Japan. The plan called for an investment of 130 billion yen (about $1.25 billion) and will boost Sharp's production capacity by 90,000 680 x 88-mm substrates per month, which could yield 360,000 units of 20-inch panels per month.

The high-aperture LCDs will be the main products coming from Fab 2. Sharp also intends to apply the UHA technology to its other LCD fabs eventually. The five products to be manufactured starting in August are a 13.3-inch-diagonal SXGA+ (1,400 x 1,050-pixel) display; a 14.1-inch SXGA+ model; a 15-inch SXGA+ display; a 15-inch UXGA model; and a 20-inch UXGA model. All will offer better than 100-pixel/inch resolution.

The SXGA+ models will deliver 150 nits with one backlight that consumes 3.9 W; UXGA models will provide 200 nits with 16-W power consumption for the 15-inch panel and 29 W for the 20-inch panel.

LCDs with 200-pixel/inch resolution are said to rival the imaging quality of film and "display the feel of material quite well," said Hijikigawa. "Several manufacturers have announced LCD TVs, and the future of the market is bright."