The new pixels use two tiny micromirrors to pass or block light. The first is a 100-micrometer-wide, 100-nanometer-thick aluminum disc with a hole in the center. The other mirror, also a thin aluminum film, is as big as the hole and placed directly in front of it. Light is projected on the disc-shaped mirror from behind the second mirror.
In the “off” state, both mirrors reflect light back to the source, so nothing comes out of the hole. In the “on” state, a voltage applied between the disc and a transparent electrode bends the disc toward the electrode. Now, light bounces off the disc toward the second mirror and then out through the hole.
Sinclair and his colleagues fabricate the pixels in a layered fashion similar to that of silicon chip fabrication. He says that the telescopic pixel design is simpler than the design of an LCD, with fewer layers, so the fabrication would require fewer steps. Right now, the researchers use indium titanium oxide, the industry standard for making transparent electrodes. But they suggest making the electrodes with an extremely thin, patterned aluminum layer that would be nearly transparent. This could simplify the display’s production process and decrease its cost even more.
The new pixel technology has advantages over current LCDs, says Peruvemba, but the mechanical parts might compromise robustness. “There are literally hundreds of thousands to millions of little shutterlike devices that have a mechanical movement,” he says. “In most devices, what fails first are the mechanical parts.”
While LCD and the new telescopic display transmit light from a backlight, others have come up with promising pixels that reflect ambient light. Qualcomm’s new display, which has MEMS-based pixels, is set to debut this year on three different cell phones. (See “E-Paper Displays Video.”) The company has also announced its first color screen for an MP3 player. Meanwhile, E Ink, which sells black-and-white e-paper displays, has now made color and video prototypes. (See “E-Paper Comes Alive.”) The e-paper technologies have a niche market: low-power screens for outdoor use.
These displays do not need a backlight, and their pixels do not need the constant refreshing required in an LCD, which slashes their power use. And the more light, the better the screens look. “We’re not competing with bright ambient light–we’re taking advantage of all that sunlight,” says Brian Gally, director of engineering at Qualcomm MEMS Technologies. “So it’s really analogous to paper.”
Sinclair says that Microsoft Research is targeting large, low-cost computer screens. That could be an IT worker’s dream. Instead of having a small desktop monitor on which you have to switch between windows, a techie could have a “whiteboard-sized thin screen” to work on, Sinclair says.