12 June 2007

New Display Technology
Could Boost Battery Life 50 Percent

Cell-phone and laptop batteries could last up to 50 percent longer, thanks to a new type of display technology that's being developed by Clairvoyante, a company based in Cupertino, CA.

Clairvoyante announced last month that it was introducing technology that could allow cell-phone, digital-camera, and laptop makers to develop power-saving displays that could dynamically adjust their backlight and color intensity based on the color and brightness of the content. Altering the intensity of a screen's backlight isn't a new idea. For instance, Nokia phones includes light sensors that determine how bright the backlight should be.

But Clairvoyante approaches the problem from a different perspective. Its displays are based on a novel pixel architecture, which it calls PenTile: a pattern of red, green, blue, and white pixels (conventional displays rely on red, green, and blue only) combined with image-processing algorithms to adjust the brightness of individual pixels. By adding the extra white pixel into the mix, says Clairvoyante CEO Joel Pollack, a PenTile display gives brighter whites, darker blacks, and sharper fonts--a feature especially useful for small, handheld screens.

Pollack says that the PenTile pixels are 33 percent larger than conventional pixels. Because the pixels are larger, more light gets through. "Often we double the amount of light throughput," Pollack explains, "so we can run at twice the brightness or half the power." PenTile--which Pollack expects to first appear in products by early 2008--also includes algorithms that perform a "sharpening routine" to eliminate any sort of fuzziness around edges as well as moiré patterns, or image defects, that would normally come from the pixel arrangement.

In many cases, PenTile displays look better than traditional red-green-blue displays, says Pollack, but sometimes they don't. Icons and some graphics in user interfaces and Web browsers can employ colors that "wouldn't appear in nature," he says, and PenTile has a difficult time recreating them. But because each pixel is individually controlled, it's possible to turn down the white pixels, while turning up the backlight so it looks more like a typical red-green-blue display.

This could be useful, Pollack says, in the case of someone building a cell phone that would run video--which could take advantage of all the PenTile pixels--and that would run conventional Web browsers or calendars, in which the backlight is turned up and white pixels are turned down.

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