Firm turns a page in designing prototype flexible display

IMAGINE an electronic signboard that wraps around your finger.

The first flexible displays, made with a technology known as electronic ink, could be on the market within two years, according to the people who are working on them at a handful of laboratories.

Initially, the displays will be simple ones with lettering two inches to four feet high -- the sort of thing that sits by the side of a highway to warn of trouble ahead or advertises specials at a convenience store.

But within a decade, their developers hope, they could lead to electronic books with paper-like pages and illustrations that move, newspapers that update themselves, reusable paper displays for cellular phones, disposable TV screens and even electronic wallpaper.

The idea is nothing new. It's been around for nearly two decades, a topic of research at such places as Xerox Palo Alto Research Center and Exxon Corp.

Now, E Ink, a Massachusetts company formed about a year ago to develop the concept, says it has a working prototype for the larger displays and expects to have products for sale by the end of next year.

If familiar store signs were made with electronic ink, someone sitting at corporate headquarters could rewrite the advertising banners at hundreds of locations simultaneously by sending out radio signals, said Russ Wilcox, vice president of business development for E Ink.

Other companies have similar projects in the works.

Researchers at Xerox PARC say they're still at least two years away from marketing their own version of electronic ink, known as Gyricon, with similar applications.

And in New Jersey, a scientist at Bell Laboratories is working on an ink that takes its color from the same natural purplish pigment that helps to tint the salt ponds around San Francisco Bay.

``The paperless office has long been predicted as the ultimate goal of electronic information systems,'' said Robert Wisnieff, manager of IBM's advanced display technology laboratory in Yorkstown Heights, N.Y., in a commentary last week in the journal Nature. ``But now paper is fighting back.''

One of the most vocal promoters of electronic ink has been Joseph Jacobson, a physicist at the Massachusetts Institute of Technology's Media Lab who invented the methods that are being further developed by E Ink.

The long-term goal is to create an electronic book that contains a whole library of reading material. Unlike today's electronic books -- small, portable computers with conventional screens, built for the sole purpose of displaying text and able to access a variety of published works -- this one would have pages with the look and feel of paper. You could take the book to the beach and stick a finger between pages to hold your place while you grab a handful of corn chips.

If you finish your novel in mid-vacation, no problem; just call up another one from a computer in the book's spine, or download something from the Internet through a wireless modem. The words on the pages rearrange themselves almost instantly.

In almost any printed publication from books to newspapers, the words on the page are a collection of tiny dots. The more dots per inch, the finer the quality of the printing. The same holds true for text on a computer screen.

With electronic ink, the goal is to produce dots that can change color in response to electrical signals. And the instructions for making those changes could be transmitted long distances using radio and wireless receivers.

Jacobson and his group described their latest approach to the technology in a report last week in the journal Nature.

To understand it, think of a beach ball.

The beach ball is perfectly clear. Inside it are dozens of pingpong balls floating in a dark fluid. Look at the ball from the top and it's white; look at it from the bottom and it appears dark.

Now imagine millions of these beach balls, each far too small to be seen with the naked eye -- so small that more than 30 would fit into the period at the end of this sentence -- sandwiched between two clear, flexible pieces of film. Each microcapsule contains a dark fluid and hundreds of white paint chips.

A grid of electrical circuits printed onto the back of the display with conductive ink controls the movements of the particles, attracting or repelling them. Where the electricity repels them and pushes them to the front of the display, it looks white. Where it attracts them toward the back of the display, the viewer sees the dark fluid instead.

While the resolution of these displays is still quite low -- about 100 dots per square inch, 1/10th of the resolution of the typical notebook computer screen -- they have a number of advantages, Wilcox said.

They weigh much less than a conventional computer screen, and can be applied to almost any surface, curved or flat. They can be viewed from any angle and in bright, direct light. ``This technology, like no other, looks like real ink on paper,'' Wilcox said.

The patterns can change up to 10 times a second, based on the time it takes the particles to dart back and forth across the microcapsule. In the Nature report, the researchers say they have switched patterns back and forth more than 10 million times with no decline in performance.

And once a pattern forms, it persists indefinitely, without any need for additional power, he said. Conventional signboards require a constant flow of juice.

IBM's Wisnieff said this is ``one of the technologies you have to keep an eye on.''

``The original papers were really interesting,'' he said, ``but the question always occurs to you -- how are you gonna do that? How are you gonna make a product?''

Now, he said, ``This is the break where it goes from being really true research to something you could actually see on the street. (Jacobson) has got a cheap way to convert voltage into something you can see. Because of that, he can attack certain large-area applications that are just unaffordable today'' -- things like freeway signs, for instance.

The next step -- displays that offer the fine detail of today's books, newspapers and computer screens -- will not be easy, Wisnieff said.

The problem is how to jam enough circuitry onto a flexible page to individually control the colors of thousands of dots per square inch. To do that, scientists will have to incorporate diodes or transistors, devices that allow much more subtle manipulation of the electric current.

That's potentially expensive. A notebook computer screen that uses this system, known as active matrix addressing, costs several hundred dollars today, Wisnieff said. ``If your book costs $300 a page, you've got a pricey book.''

Jacobson's group says it has already found a way to print diodes cheaply and simply on the circuitry. But it will take years to perfect the technique for use in commercial products, Wilcox said.

In the meantime, researchers at Xerox PARC are working on their own system. It involves tiny spheres about twice as wide as the E Ink microcapsules. Each one is half black and half white. The spheres are embedded in a flexible sheet of plastic and are surrounded by a fluid, so they're free to rotate. As in the E Ink system, the movements of the spheres are controlled with electricity.

And at Bell Laboratories, Paul Kolodner and his colleagues are focusing on a protein called bacteriorhodopsin, from bacteria that live in salt marshes.

This protein can also shift color, from its original purple to yellow, in response to an electric field. A mutant form switches from pale yellow to blue -- providing enough contrast to serve as electronic ink.

The main hang-up, Kolodner said, is that it would take several thousand volts of electricity to trigger the color change -- not yet in the realm of practicality.

John Knights, principal in market and technology innovation for Xerox PARC, said his company considers electronic ink ``a very fertile area for technology.''

``We don't think it will replace paper,'' he added. ``It will almost certainly supplement paper and replace some of its uses over time, but it's not going to blow paper away. But if it made 10 to 20 percent of the paper market over 10 years' time, that would be a very significant business for anyone who's in it.''

But while the first applications seem to be coming along nicely, Wisnieff said, ``Notebook computer makers and TV makers can keep doing what they're doing for a while yet.''

More information on E Ink can be found at the company's Web site, http://www.eink.com .