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E-papers ready for reality

Flexible display screens are getting ready for commercial production.  The technology could eliminate bulky books, piles of paper and even find itself on  clothes.
/ Source: a href="http://www.washingtonpost.com/wp-srv/front.htm" linktype="External" resizable="true" status="true" scrollbars="true">The Washington Post</a

The trail has disappeared and let's face it, you're lost in the woods. But luckily you've got your trusty map rolled up in a pocket. You unroll the plastic-coated sheet ... it's blank — until you turn the power on.

Suddenly the curly page jumps to life with a detailed screen display, including a selection of topographic maps showing the way back. Later, at your car, you unfurl the same sheet, this time to check out restaurant reviews for local eateries.

Scenes like this one have long been imagined by techno-optimists. But reality has repeatedly delayed the introduction of flexible electronic displays. Even today's thinnest and fanciest display screens for laptops and digital assistants are topped with a layer of glass or plastic that cannot be folded, bent or mutilated — much less rolled up into a handy little tube.

But after years of unabashed hype and dashed hopes, truly flexible displays are at last being ramped up to commercial production. Among the uses that manufacturers foresee are electronic newspapers that can be folded or rolled when not in use and then opened to display the latest news; flexible strips for store shelves that display constantly updated price and product information; and watch bands or bracelets that offer streaming news or other information.

High-tech clothes
Some companies are even considering working the technology into lines of clothing. Forget those low-tech embroidered Gap or Gucci logos on your shirts, said Barry Young, vice president and chief financial officer for Austin-based DisplaySearch, a market research company that tracks the flat panel display industry. We're talking about a Times Square-style news crawl moving across your chest: G ... U ... C ... C ... I.

"Now we'll have to pay to be a billboard," Young quipped.

Flexible-display blouses are still some years off. But a more modest rollable display — the first to be truly mass-produced — is now being churned out at the rate of 100 per week and may reach production levels of 1 million a year by the end of next year, said Bas J.E. van Rens, general manager of Polymer Vision, the division of Royal Philips Electronics of the Netherlands that makes the display.

The device is a rectangular screen just three times the thickness of a sheet of paper and measuring five inches diagonally. It curls into a tube less than two inches in diameter and may soon coil to the diameter of a fountain pen.

With the exception of some invisibly fine gold wires, the circuitry that's inlaid into this flexible page is completely plastic. An internal layer of "electronic ink drops" creates black text on a white background, giving the plastic sheet the look of a paperback page.

The whole thing weighs just 3.5 grams, or about the weight of 11/2 pennies. When it is dropped, van Rens said, it doesn't shatter into a heap of glass shards and electronic guts. "It just flutters to the ground," he said.

Means for arrival
Two advances underlie the arrival of flexible computer displays. One involves improvements in electronic paper, or "e-paper" — thin plastic sheets packed with closely spaced black and white dots, or pixels, that can be electronically rearranged many times per second to create ever-changing messages. The other involves breakthroughs in the field of "organic electronics," in which scientists are making transistors and other electronic components out of plastic instead of rigid silicon and metal.

The Polymer Vision screen, described in the February issue of the journal Nature Materials, uses e-paper technology developed by E Ink, a Cambridge, Mass., company. Embedded in a thin sheet of plastic are tiny capsules smaller than the period at the end of this sentence, each filled with thousands of particles, some black and some white. The black and white specks have opposite electronic charges, so depending on whether a positive or negative charge is applied to that capsule, either the white or the black specks leap to the sheet's visible surface at that spot.

By applying positive or negative charges in pinprick patterns across the "page," the black and white specks can be arranged to make letters and words that look just like those printed with ink on paper.

Unlike standard computer and PDA displays, which generate tiny points of light, the E Ink system simply reflects ambient light off its white background, like a newspaper or book. So it is easily read outdoors in bright sun and at virtually any reading angle. Light-emitting screens are difficult to read in bright places and must be viewed fairly straight on.

The E Ink system also draws far less power than light-emitting systems because it needs energy only to set the image, which remains visible without additional power until it's time to "turn the page" — that is, call up the next image.

A thin layer of plastic underlying the display contains the electronics — including a paper-thin array of 80,000 plastic transistors, each of which is a minuscule electrical switch that can create a dot of white or black on the overlay.

More companies involved
Similarly flexible plastic electronics are being made by other companies. Plastic Logic of Cambridge, England, uses specialized dot matrix printers to literally print its circuitry onto a polyester backing instead of etching its transistors from layers of plastic, as Philips does. And several big corporations, including DuPont, Siemens AG and Xerox Corp., are now racing to integrate flexible circuits into a variety of products. Prototypes typically allow for internal storage of images (such as maps) as well as an ability to download fresh information via either an internal antenna or cell phone. The display would feature scrollable menus and a few flexible point-and-click keys for entering commands.

Experts say flexible screens will be aimed first at specialty niches — including the military, which, among other things, is thinking about the technology for its uniforms — not to say "GUCCI," but to change shades to match surroundings and to display enemy coordinates on constantly updated wrist bands. Stores want rollable, portable display boards with moving messages, and radio-controlled "Sale" signs for clothing racks that can suddenly declare "10% Off!" at the click of a computer mouse.

Consumer applications, such as e-maps and e-newspapers that roll up like window shades, remain a few years off, but a stiff version of e-paper is about to hit the market. This spring, Sony is expected to release an e-book using Philips and E Ink technology — an electronic reader about the size of a paperback that can be loaded with a library full of literature without cutting down a single tree. E-books would also have the advantage of being potentially searchable by key words and could have built-in dictionaries.

Analysts envision a future in which students will trade their bulky backpacks full of books for a single all-purpose e-text. And with the capacity to download a few comic book programs as well, students may even free themselves from the age-old hassle of hiding the latest issue of Spiderman comics inside the cover while pretending to study.