Flexible Displays Closer to Reality, Thanks to U.S. Army

Oct. 30, 2008— -- Imagine a screen so thin, light and flexible that it can be rolled up and carried in your pocket, while consuming almost zero power.

That technology could become reality in two to three years, thanks to U.S. Army-backed research being done at Arizona State University's Flexible Display Center. According to Army researchers, the displays could be in field trials with soldiers as early as 2010 or 2011.

"The Army's motivation is to give soldiers the best situational awareness," says David Morton, U.S. Army research laboratory manager for the center. "Flexible display technology can enable us give soldiers information in ways we can't now."

These flexible displays have been the dream of science fiction authors, wearable-computing enthusiasts and the display industry for nearly a decade. LG Philips, Fujitsu and Sony have shown off prototypes of flexible-display systems, while startups such as Plastic Logic and E-Ink have talked about the possibility of putting their digital ink displays onto bendable backings. But so far the idea has remained more in the realm of Minority Report than the real world.

The research center, formed through a partnership between the the Army Research Laboratory and the university, has been working on creating flexible displays since 2004. So far, the U.S. Army has invested nearly $44 million toward the research.

"We are now at a point where we are making where making high quality tech demonstrative panels," says Gregory Raupp, director for the center.

The Army is interested in small displays that can be folded up, have very little weight and won't break. They will allow the military to send greater information to soldiers and replace many of the bulky devices that they carry currently.

For instance, a soldier in the field could get information about the surroundings, the position of enemies or the blueprint of a building he or she may be planning to enter. Other applications could include the use of the flexible displays as maps.

Flexible displays -- when they arrive -- will be a big leap from today's liquid crystal displays (LCDs) and even organic light-emitting diode-based displays (OLEDs).

Consider the difference in power consumption. The flexible displays will consume 100 times less power compared with LCDs. Even OLEDs, which are two to three times more efficient than LCDs, can't match that kind of efficiency.

The center is focusing on electrophoretic ink-based displays that are extremely low power and flexbile, says Raupp.The displays have thin-film transistor arrays on specialty polymer and thin stainless-steel substrates and use electrophoretic ink (E Ink), among other technologies, to render the characters.

E Ink, from a Massachusetts Institute of Technology spinoff, is composed of tiny microcapsules, each of which has positively charged white particles and negatively charged black particles suspended in a clear fluid.

Once a polarized electric field is applied, the particles move to the top or the bottom of the microcapsule, depending on the polarity of the charge. Alternating between the white and the black particles helps render characters and images on the screen.

To form a display, the e-ink is printed on to a sheet of plastic, which is laminated to control circuitry.

An early prototype has a soldier holding a flexible PDA weighing just 13 ounces and featuring an E Ink frontplane and a low temperature amorphous Silicon TFT backplane.

Currently, the center is looking at two kinds of flexible displays: a reflective display (which relies on ambient light) known as a "zero power" version for its almost negligible power consumption and an emissive low-power model that emits its own light. In comparison, an LCD relies on backlight.

The reflective displays are the most promising as they only require power to switch the transistors in the pixel array to update the image and have no backlight so power for fixed image viewing is very low.

"We need to look at technology that is fairly far along in the path towards commercialization," says Morton.

It is also evaluating additional materials and manufacturing issues to get the displays into production devices, says Morton. It hopes to have them in limited field trials within the next two to three years, and is working with companies such as LG to commercialize the technology.

"Our goal is to speed development of the displays and make them available for commercial manufacturing soon," he says.