Paper 2.0

An IEEE senior member is working on a new kind of color e-reader display

6 January 2011

What if you could take the vibrant colors and touch screen features of the iPad and the color version of the Nook and merge them with the readability and low power of the displays on the Kindle and Sony Reader? You’d have a recipe for a perfect color display.

That’s what IEEE Senior Member Jason Heikenfeld is counting on. He’s spent the past five years rethinking how e-paper—a screen that imitates ink on paper—works. Heikenfeld is an associate professor of electrical engineering and director of the Novel Devices Laboratory at the University of Cincinnati, as well as cofounder of the Cincinnati start-up Gamma Dynamics. Now his company is less than three years away from manufacturing near-print-quality e-paper that can also handle video and the Web.

Devices like the Kindle use an e-ink/e-paper technology that makes the display approximate real paper, which is easier on the eyes and can be read in the sun. They’re also as light and portable as a book because they use reflected light rather than a backlit screen. These e-paper readers don’t run video, however. The color Nook and iPad, on the other hand, use an LCD screen, just like computer screens, to display bright colors. And you can browse the Web and watch video on the iPad—features e-paper readers don’t provide. But LCD screens are difficult to see in sunlight, can strain your eyes, and are heavier because they require more power and hence bigger and heavier batteries.

Heikenfeld’s e-paper uses significantly less power than LCD technology. Unlike LCDs, it doesn’t have to continuously force light through a near-opaque screen, wasting 93 percent of the light.

He expects his e-paper not only to combine the best features of e-ink readers and LCD tablets but to lead to improvements in the brightness of reflective display devices beyond e-readers. Such applications could include electronic pricing signs on store shelves, billboards, and displays that can be rolled up and transported. Competition to advance e-paper technology is fierce: Some 200 companies (only a dozen of which Heikenfeld deems major players) are vying for a stake in e-paper’s anticipated US $9.6 billion market by 2018, according to DisplaySearch, a Santa Clara, Calif., research firm.

Past industry attempts at e-paper with color, sharper black-and-white imaging, and pixels responsive enough to handle video (all on low energy) involved side-by-side color filters—red, green, and blue—laid over black and white pixels. Software then coordinated combinations of electrodes to create a color palette. But the approach failed for a number of reasons, including not creating a bright enough display or good color saturation, according to Heikenfeld.

Heikenfeld’s take is different. Pixel-generated voltage pulls colored fluids out of holes and between two conductive plastic sheets and spreads them across the entire reflective surface to form an image. When the voltage is turned off, the surface tension of the liquid pulls it back into a droplet shape—a so-called electrofluidic process that can occur rapidly enough to play video. In addition, these pixels handle several colors at once so they’re in use all the time, avoiding the dim appearance of side-by-side color filters, which assign one color to each pixel. The resulting e-paper, relying on reflected light, will equal the print quality of magazine text and, in color form, is expected to be twice as bright as the side-by-side color filter approach.

“The technology is truly unique,” says Heikenfeld. “Unlike the Kindle, which moves pigment particles through a fluid, we move the fluid itself and carry the pigment particles along with it, which is 100 times faster over the same distance traveled.”

DRAWN TO DISPLAYS
Heikenfeld has been interested in developing electronic devices like displays since high school. “It’s exciting to start with raw materials and build up a finished, working screen,” he says. By 2001, he’d earned a bachelor’s, master’s, and Ph.D. in electrical engineering, all from the University of Cincinnati. His Ph.D. research focused on a new type of LED for televisions. “It was a completely different technology, involving semiconductors that generated colored light inside each pixel,” he says. The technology was not adopted, as LCDs quickly became dominant in the large-screen TV market.

After graduating, Heikenfeld spent four years as a principal scientist for Extreme Photonix, a Cincinnati start-up he founded with his Ph.D. adviser, IEEE Fellow Andrew Steckl. Some of that research has now been commercialized as new transparent light-emitting displays for toys and signs. He and Steckl closed the business in 2005 while Heikenfeld was completing interviews at several universities to begin his career as a professor.

The following year, Sun Chemical, a Cincinnati manufacturer of colorants, approached Heikenfeld to collaborate on new uses for its ink products in electronic displays. Sun provided the colored fluids, and Heikenfeld worked on creating the display device using those fluids. In 2009, he formed Gamma Dynamics to commercialize the new technology, and last year he unveiled the first working prototype. The start-up, which is working with Sun Chemical and an undisclosed display company, hopes to demonstrate the next generation of the technology in Los Angeles in May, at the Society for Information Display’s annual conference.

“I’ll be researching e-paper for some time to come. It’s more than just a better product, it’s also a green technology,” says Heikenfeld. “Even with the improvements we are making for e-paper, there is a lot of work remaining to be able to provide all the color and video function the consumer ultimately desires.”

Additional information and scientific papers can be found at Heikenfeld’s Web site.