For years, analysts have been predicting that electronic paper, or e-paper, would set the stage for the paperless office. Until recently, however, developing a paper substitute was not an easy proposition. And even today, business applications of the technology remain limited.

E-paper is a thin, flexible polymer sheet with the look of paper. But e-paper is a bit thicker than regular paper and weighs more because it contains microscopic electronic ink particles sandwiched between two polymer sheets that display as either white or black in response to an electrical charge.

E-paper is reflective, like real paper, so it can be read in any light. It uses no backlighting, as LCDs do, nor does it use an emissive light source, as with a CRT monitor, says Tom Ashley, director of Pivotal Resources USA, a research firm that follows the digital printing market.

E-paper is also bi-stable, which means that the display uses power only to change the content. Once the image is created, it stays there, even when the power is turned off, Ashley says.

"Those two main characteristics are what give a paperlike display its good qualities -- it's comfortable to read because it's reflective, and the bi-stable aspect allows you to have low power and lightweight batteries so the whole device could be extremely thin and lightweight," Ashley says.

Several companies are developing commercial applications of e-paper technology. SmartPaper, an e-paper technology from Gyricon, first appeared in an e-paper pricing-sign system for retail stores in May. The sign is controlled by software that links it wirelessly to in-store pricing databases, says Robert Sprague, chief technology officer at Gyricon, a wholly owned subsidiary of Xerox.

"We'll replace the paper pricing signs on each retail rack in retail stores with an electronic paper sign, which is wirelessly networked to the store's central computer so the price on the sign can be updated instantly. And it's always the same as the price in the point-of-sale database," Sprague says.

"This gives IT departments a way to control a lot of signage and information around an entire building or campus from one centralized computing point," Sprague adds.

Gyricon also offers SmartPaper in a line of dynamic message boards, which it sells to hotels, conference centers and large campuses, he says.

The E-book

In April, E Ink, Philips and Sony together launched their first-generation e-ink display in Sony's e-book reader, the Librie, in Japan. The e-book incorporates the e-ink technology used in e-paper into a traditional display.

E Ink's electronic ink is a proprietary material that is processed into a film for integration into electronic displays.

"For the Librie product, we make our e-ink as a film, a sheet of plastic that gets sold to Philips Electronics. Philips makes the display, and then the display is sold to Sony and put into an electronic reader," says Darren Bischoff, E Ink's marketing manager. "We're part of an enabling component for making that a paperlike reading experience."

Currently, users can download and store 500 books of about 250 pages each to the Librie e-book reader, which is similar in size and design to a paperback. The cost of the device is approximately US$370, but Sony has no plans to release it outside of Japan.

Both E Ink and Gyricon have developed electronic shelf labels that can change prices automatically. E Ink's labels are wirelessly tied into the store's pricing system, Bischoff says.

E Ink's ultimate vision is to develop a next-generation smart paper, which E Ink calls RadioPaper, in the next several years. "Now we can make something that visually looks like paper, but we want something that feels like paper as well," Bischoff says.

E Ink's current e-paper looks like paper in terms of high contrast and a reflective surface that can be read at any angle, he says.

"The majority of the development to create something that is closer to the feel of paper has to happen with materials and developments other than the electronic ink component," Bischoff says.

To that end, E Ink is working with Philips' research department to create thin, flexible, rollable e-paper.

E Ink predicts that displays made with its e-ink technology will eventually appear on electronic devices ranging from handheld computers to cellular phones, calculators, digital watches and car dashboards.

Fujitsu Laboratories in Japan is developing a paperlike display that it says could be used with a terminal for reading business documents downloaded from a PC, says spokesman Isao Hirano. The paper should be in production by 2006, and Fujitsu is bullish on its prospects. "We expect that this invention would pave the way to a paperless office and reduce paper consumption," Hirano says.

Although e-paper technology is progressing, there are some downsides. One is that e-paper lacks color, says Pivotal's Ashley. And while e-ink has been incorporated into displays such as the Librie, the bi-stable e-paper technology can't support full-motion video because updating or rewriting a page takes too long, according to Kenneth Werner, editor of Information Display Magazine, published by the Society for Information Display.

Today, e-paper is still looking for a killer application. While a few retailers are experimenting with e-paper pricing labels, the technology has yet to catch on. But that could change.

"In three to five years, we'll see second-generation technologies from the companies that are launching products now that will probably have better characteristics, reduce costs and add flexibility to the mix," Ashley says.

Inside E-paper

Electronic paper is a thin, flexible sheet with the look and feel of paper. It contains microscopic particles that display as either white or black in response to electrical charges. E Ink and Gyricon both offer products. The basic technology the vendors use is the same, but each takes a slightly different approach.

E-Ink

E Ink's e-ink consists of millions of microcapsules about the diameter of a human hair. These clear capsules contain a clear fluid, as well as tiny black and white particles. The two colors each carry opposite charges. When an electrical field is applied, the particles move up and down within the capsules. A negative electric field makes the white particles move to the top of the microcapsule, where they are visible to the user. A positive charge pulls the black particles to the bottom of the microcapsules, hiding them. The technology is used for e-paper and can be embedded in electronic displays.

SmartPaper

Gyricon's SmartPaper consists of two sheets of thin plastic with millions of tiny beads embedded between them. Each bead, smaller than a grain of sand, has a different color on each side. The hemispheres also carry opposite charges. Each bead resides in its own oil-filled cavity within the flexible sheet, and under the influence of a voltage applied to the surface, it rotates to present one side or the other to the viewer. The image stays in place until a new voltage pattern is applied, which erases the previous image and generates a new one.