Display Week 2010 Review: Flex and e-paper

e-paper technology rebounds with some colorful new possibilities

by Robert Zehner

WHAT A DIFFERENCE a year makes. As I walked the show floor during Display Week 2010, I could not help comparing the state of SID, and of the e-paper industry, against where they both were a year ago in San Antonio. By all measures, Display Week 2010 as a whole has bounced back, with attendance up nearly 100% over last year. e-paper exhibitors who were completely absent from last year's show were back this year with impressive improvements in the performance of their prototypes. Meanwhile, mainstays such as Prime View International (since re-named E Ink Holdings), LG Display, and Samsung continued to show ever more impressive flexible and glass e-paper panels, with features such as in-cell touch and improved color rendition. It's certainly reassuring to see that so many e-paper companies and technologies are weathering the economic storm and are back in growth mode.

On Monday during Display Week, the DisplaySearch Business Conference took place, and Jim Cathey, Vice President of Business Development from Qualcomm MEMS Technologies, compared the current state of the e-reader market to what his company previously experienced in the handset market; as readers evolve from monochrome, static-page viewers through the addition of color, video, and interactivity, the power demands of the devices will skyrocket, while battery technology will continue to improve by a meager 3–5% per year. "When we look at the market for e-readers," said Cathey, "we see history repeating itself." He posits that the only way to break this cycle is by adopting full-color video-rate reflective display technologies with ultra-low static power consumption. Further, Cathey stated that longer battery life will increase average revenue per user (ARPU), the key measure of success for mobile network operators. His reasoning is simple enough: a device with a dead battery cannot be delivering advertising impressions to its owner.

Cathey's comments, while intended to promote Qualcomm's own mirasol^® display technology, are clearly influenced by the entry of the Apple iPad into the tablet market in April 2010. In contrast to e-book reading devices from Sony, Amazon, Barnes and Noble, and others that achieve long battery life by using image-stable displays, Apple paired a backlit LCD with a substantially larger and heavier battery to deliver up to 10 hours of use per charge. The common goal for all of the e-paper vendors that I spoke with is to develop a display with color animation capability, while maintaining ultra-low power consumption and excellent viewability, ultimately combining the performance of a tablet computer like the iPad with the thinness, light weight, and long battery life of an e-reader.

On the show floor, Qualcomm had numerous working samples of its mirasol^® displays, including several samples of a 5.7-in. color XGA module. (Fig. 1). These prototypes showed marked improvement in color saturation over demonstrators from previous years, while delivering 23% brightness with an 8:1 contrast. Qualcomm representatives indicated that they expect pilot-scale production to begin in late 2010, with full mass production to follow.

Fig. 1: Qualcomm exhibited color and monochrome 5.7-in. XGA displays built with its mirasol^® MEMS technology.

Electrowetting-display manufacturer Liquavista was also represented in the business conference. In his talk, Liquavista CTO Johan Feenstra emphasized that customers expect future e-reading devices to deliver color and video performance, with good power consumption and low cost. Without going into detail, Feenstra explained that Liquavista can vary the addressing scheme for its displays to trade-off power consumption and response speed, which would support both full-speed video at higher power, and static viewing with much lower battery drain. Accordingly, Liquavista exhibited a color-filter-array display showing both magazine pages and simple animations (Fig. 2). A static display with a flashing colored backlight hinted at the company's planned LiquavistaVivid platform, which will combine a mono-chrome reflective operating mode for reading and outdoor use with a color-sequential backlit transmissive mode for indoor use.

Fig. 2: Liquavista's e-reader prototype display achieves color via a color-filter array atop a monochrome electrowetting medium. Future generations may use a color-sequential backlight instead.

In the particle-based display arena, Japanese display developer Bridgestone had previously shown high-quality color and monochrome signage products that were limited by a relatively slow update time. Although Bridgestone's quick-response liquid powder (QR-LPD) can be switched in a matter of milliseconds, refreshing the display previously required multiple scans through each line, taking 10 sec or more. At this year's show, Bridgestone demonstrated its AeroBee e-book concept, an A4-sized color reader with pen-based touch and real-time handwriting recognition. According to Bridgestone representatives at the show, the improved response was achieved by only updating the portions of the display that are changing, leading to almost instantaneous transitions for mark-up with the pen. By using the same update method, the AeroBee prototype was also able to show video clips, although the animation was limited to the bottom portion of the display and appeared somewhat blocky.

E Ink, a name that has become almost synonymous with e-paper, has undergone some corporate changes over the past year. The Cambridge, Massachusetts-based start-up was purchased in December by Taiwanese display-maker Prime View International. Then, in mid-June (several weeks after SID), Prime View changed its name to E Ink Holdings, in recognition of its commitment to the e-paper business. "The E Ink name is synonymous with the e-paper industry that we pioneered and in which we enjoy a leadership position," said Dr. Scott Liu, Chairman and CEO of E Ink Holdings, Inc., of the name change.

E Ink's technology was represented in multiple places at SID, both in its own booth and in demonstrators shown by display-makers LG Display and Samsung. All three companies showed off their latest generation of color demonstrators on both glass and flexible substrates, in sizes ranging from 6 to 11 in. on the diagonal, consistent with E Ink's plans, announced earlier this year, to commence production of color displays by the end of 2010. E Ink's booth also included a gallery of over 20 different e-reader products from around the world that are currently in production using the company's technology.

It's worth noting for a moment that none of the commercial e-reader products featured in E Ink's booth (or anyone else's for that matter) yet include a non-glass (flex) display module. Plastic Logic pre-announced its Que reader at CES 2010, but is not yet shipping product as of this writing. Rollable-display- developer Polymer Vision declared bank-ruptcy in 2009, only to be snapped up by Wistron, a major Taiwanese OEM, which has so far been quiet about any possible product launch. Skiff, formerly a division of Hearst Corp., previewed a reader based on LG Display's 11.5-in. stainless EPD at CES – but Skiff's recent sale to Rupert Murdoch's News Corporation explicitly excluded the reader hardware. Nonetheless, with multiple vendors producing increasingly compelling flexible prototypes, one would hope that a volume product launch is still just around the corner.

In the display industry, the name Merck (officially called EMD Chemicals here in the U.S.) is synonymous with liquid-crystal chemistry. LCD researchers and manufacturers around the world rely on Merck to supply just the right LC mixture to produce their desired display effect. According to Merck's Mark Goulding, the company may be about to expand its reach into materials for e-paper. In an invited symposium talk delivered as part of Wednesday afternoon's e-paper session, Goulding showed his promising results in synthesizing a variety of brightly colored particles and compounding them into electrophoretic suspensions.

Particle electrophoresis is the core technology behind EPD companies such as E Ink and SiPix Imaging, which to date make up the lion's share of e-paper products on the market. Today, these companies formulate their own materials using closely guarded recipes. In his talk, Goulding suggested that Merck is evaluating whether to offer its own electro-phoretic mixtures in the market, which could open up an opportunity for other display companies to experiment with this hot new technology. This probably will not happen tomorrow since Merck's formulas will need more fine tuning before rolling out. As an example, Goulding was not ready to comment on image stability, saying only that it is an area of active research at the moment; image stability is what allows e-readers to keep their image for a long periods of time without requiring a refresh and is critical to ultra-low-power operation of EPDs.

With an established and building demand for reading devices, the e-paper-display business segment is growing and maturing as quickly as ever. While electrophoretic displays have taken an early lead, competitors are redoubling their efforts to bring a variety of competing technologies to market. At the same time, Apple's launch of the iPad with a backlit LCD presents a new set of challenges and opportunities for ultra-low-power displays. All in all, the next year promises to be at least as interesting as the past one for e-paper. •