More-Efficient Phone Displays

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Each pixel in a liquid-crystal display consists of three subpixels--one red, one green, and one blue--that work together to produce a gamut of colors. A Unipixel display doesn't have subpixels; the color comes from red, green, and blue LEDs located at the edge of the screen. Cox explains that the LEDs flash so quickly, and the membrane opens and closes the pixels at such a rapid rate, that the eye perceives a gamut of colors that is just as wide as that of a liquid-crystal display. (Texas Instruments takes this approach, called sequential color, for its digital light projectors, which are used for business presentations and theatrical films.)

FTIR is already used in large-scale touch-screen displays, such as those made by Jeff Han, a researcher at New York University and founder of the startup Perceptive Pixel. (See video and "Touch Screen for Many Fingers.") Han places infrared LEDs along the edges of his displays, and when a person's finger touches the screen, it scatters the light. This scatter is detected by cameras and used to determine the position of a person's finger on the screen. Han says that Unipixel's displays show "another clever use of an elegant phenomenon."

And the market is always looking for more-power-efficient displays. Today's displays "throw away so much light," says Han. "People are very gung ho about lower power in portable devices, so if you can get a substantial improvement in power efficiency, it's valuable." Unipixel's theory is sound, he says, "but like a lot of technologies, the devil's in the details." Han adds that it's hard to predict how well the company will be able to compete with existing technologies in an industry that moves so fast that displays drop 30 percent in price every year.

Unipixel is a few years away from an actual product, Cox says, but by leveraging preexisting display technologies and new materials that come along, his company can keep up with the industry. At this point, Unipixel is focusing on displays for mobile devices, but Cox expects that the technology will work for large displays as well.