Display Tech To Watch This Year

Display Tech To Watch This Year: E-paper Stretches Its Wings

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New technologies on the horizon

Of course, E Ink isn't the only e-paper game in town, nor is electrophoretic technology the only option for creating e-paper displays. Many other companies are working on competing technologies.

Two of the more interesting ones are being developed by Qualcomm subsidiary Qualcomm MEMS Technologies and startup Liquavista, which was acquired by Samsung Electronics in January.

Qualcomm is working on an alternative display technology that could further shake up the e-reader market by offering better color and faster performance. Qualcomm's Mirasol display uses microelectromechanical system (MEMS) technology, which adjusts two conductive plates to either reflect light or absorb it for a series of screen subpixels.

By varying the gap between the plates and the voltage applied to them, Qualcomm can vary the wavelength of light emitted to create different visible colors. It then assembles red, green and blue subpixels into a single pixel capable of supporting an even wider range of colors. Think of MEMS as an array of very tiny, very fast shutters -- fast enough to support full-motion video.

Mirasol is nearly bistable, using a tiny amount of voltage to maintain the display. Overall it consumes between one-tenth and one-hundredth the power of an LCD, depending on the application, and its reflective screen doesn't require a backlight. The technology supports color natively, without the need for color filter or polarizer layers, so colors are brighter. "We're positioned in the center" for converged e-reader/tablet devices, says Qualcomm MEMS Technologies Vice President Jim Cathey.

Among E Ink's competitors, says analyst Hildebrand, "Mirasol is the closest to manufacturing volume." Qualcomm has been sampling a 5.7-in. display and says the first commercial e-reader/tablet to include it will arrive early in 2011. A smaller version for a much bigger market -- smartphones -- will debut sometime in 2013.

Cathey says Mirasol technology is not only more energy efficient than LCDs for tiny smartphone screens, but also more energy efficient "in general" than OLED displays.

Ken Werner, an analyst at Insight Media, agrees that because it's a reflective display, Mirasol probably would consume less power than emissive OLED technology for many applications. But for video, where refreshes occur 30 to 60 times per second, OLED might do better in some cases, he says.

Looking further out, a new e-paper display technology developed by Liquavista and now owned by Samsung also has the potential to support video. Liquavista's electrowetting technology is similar to electrophoretic technology in that it's liquid-based, but it combines an electrolyte of oil and water with a polymer layer that either attracts or repels the water droplets to create black, white or gray.

Liquavista's prototype color e-paper display (left) is fast enough to support full-motion video and is much easier to see in bright sunlight than the iPad's LCD (right). Source: Liquavista
Applying one voltage pushes the oil into a corner; another pulls it back. Like E Ink's Triton, Liquavista's display adds color by using a standard color filter.

Liquavista's approach pushes oil across a liquid surface rather than through it, which makes it faster than E Ink's electrophoretic technology. "Moving the surface compression works faster than moving particles through liquid. It's really the physics," says Insight Media's Hildebrand.

Liquavista is targeting smartphones and converged tablet/e-readers and recently demonstrated an 8.5-in. prototype display that the company says is fast enough to support video at between 60 and 70 frames per second -- well above the 30 frames per second required for full-motion video.

Former Liquavista CEO Guy Demuynck, who left the firm shortly after the Samsung acquisition, said Liquavista's technology is seven to eight times more energy efficient than a standard LCD "when images are changing or when playing video," and when the user is reading an e-book, the display lowers the refresh rate frequencies to save power. But the technology is not bistable. For viewing static text and images, such as the pages of an e-book, electrophoretic displays will squeeze more hours out of the battery.

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