[SID] Sharp Develops LCD with 5-color Filters

Jun 3, 2009
Takuya Otani, Nikkei Electronics

Sharp Corp developed an LCD that can display more than 99% of real surface colors in the natural world.

It is a so-called "multi-primary color display," which uses an LCD panel with five-color filters for cyan (C) and yellow (Y) in addition to the existing three colors, ie, red (R), green (G), and blue (B). The new display combines these filters with a dedicated signal processing circuit.

"The display can faithfully render colors that were difficult to reproduce with the existing LCDs, such as the colors of emerald blue sea, golden yellow brass instruments and crimson roses," Sharp said.

The company expects the display to be used for electronic museums, remote medical care, monitors for industrial designing, etc. It is a 60.5-inch display with a resolution of 1,920 x 1,080. The color gamut in the xy chromaticity diagram is 110% NTSC, and the gamut in the u'v' chromaticity diagram is 130% NTSC. The display has a color temperature of 6,500K, luminance of 450cd/m2 and a contrast ratio of 2,000:1.

The filters for RGBYC five colors were manufactured with photolithography and are arranged in a striped pattern. The display uses a cold cathode fluorescent lamp (CCFL) for the backlight.

The adoption of multi-primary color filters leads to energy saving because light from the backlight can be efficiently utilized, Sharp said. Compared with the existing three-color filters, the light-use efficiency can be enhanced by 20-30%, according to the company.

The development of multi-primary color displays was vigorously promoted from 2003 to 2005 when a number of manufacturers proposed various approaches. Sharp explained why it developed this type of display once again after several years have passed since then.

"Compared with the technologies back then, fine processing techniques and production technologies of color filters, etc have certainly improved," the company said. "For example, with the fine processing techniques of those days, we had to reduce the number of pixels in order to realize multiple colors. And the color filters were very crude. But now, we are finally in the phase to develop multi-primary color displays with a view to commercialization."

The new display will be presented at SID Display Week 2009, an academic conference that runs from May 31 to June 5, 2009, in Texas, the US.