E-READERS owe their existence almost entirely to the paper-like screens developed by the US company E-Ink. They are easy on the eye for prolonged reading and draw power only when their image changes, enabling devices that can run for days between battery charges.
But they are good for very little more than for reading books and other documents. Now Apple's Ipad appears to be gaining acceptance as a device for delivering not just monochrome text and still images but the full multimedia Monty - provided it doesn't use Adobe's Flash.
So where does this leave E-Ink? Very upbeat, if the mood of its vice-president of marketing Sriram Peruvemba is anything to go by. "I love the Ipad," he declared during a stopover in London, prolonged bizarrely by the dust of an Icelandic volcano.
"I love the Ipad in terms of a gaming device, an entertainment device. But the reading experience is much what I would have expected from a laptop, and I would not use a laptop for reading a document that was more than two pages long."
Apple is far from the first company to produce a mini-tablet, but no-one else has been able to make a mainstream success of one. The Ipad has revived interest in the format, Peruvemba said, and some manufacturers are interested in using an E-Ink rather than an LCD screen. "It has opened a big opportunity for us," he said.
But E-Ink is honing its technology to make it more competitive . Current monochrome E-Ink screens have a contrast ratio of six to one. New versions, shipping in products late this year or early in 2011, will double that to 10 or 12 to one.
The difference was clear on the sample screen Peruvemba showed. The white appears whiter than on the old screens, which render it as a parchment colour, but according to Peruvemba the biggest difference is in the depth of the blacks.
Colour E-Ink screens will also appear within the same time scale. The higher contrast helps with these because it offsets the light lost to the filters used to produce the colour. The filters also affect the black-and-white rendering but this should nevertheless be at least as good as current monochrome screens, Peruvemba said.
Colour also requires far more pixels than a monochrome screen of the same resolution, but this is not E-ink's problem. The company produces only the e-paper, a layer of microcapsules containing black and white particles that are oppositely charged so that their visibility can be controlled by an electronic backplane.
Different manufacturers use different backplanes, none of which can match the potential resolution of the e-paper. "We have dozens of microcapsules per pixel," said Peruvemba.
He tapped a 5-inch sample display. "The resolution on that is 800 by 600. You could add a zero to both those numbers and we could do it. You can't get the backplane density. LCD has the same problem."
Flexible versions of E-Ink screens enable new formats, such as curved devices that fit snugly to the body when pocketed and are more robust because they do not use glass.
E-Ink is also improving the response time of its products. It was so focussed on the physics of the microcapsules in this respect that it was taken by surprise when new drivers turned out to make a big difference. Texas Instruments, Marvell, and Freescale are now hardwiring these drivers into e-reader system-on-chip packages, reducing costs as well as response times.
Movement is the trickiest issue for E-Ink because its displays draw power whenever an image changes, so the faster the changes the more it erodes the technology's major advantage over LCDs.
Peruvemba showed a monochrome animation running on one of E-Ink's new high-contrast screens. "On our screen you only have to refresh the changing bits," he said. "On an LCD screen you'd have to keep refreshing the whole screen."
E-Ink has demonstrated full-screen 30 frames-per-second video at 800 by 600 resolution in the lab, and even this drew only 70 per cent of the power an LCD would use.
Peruvemba accepts that Ipad-style tablets and e-readers will converge in the long run but not for a few years. Even then there would still be a demand for specialist devices that do a single job better than a general-purpose device.
And there were huge potential markets for low-cost e-readers, particularly in developing countries where text books are thin on the ground. E-readers not only facilitate the delivery of knowledge, they make it cheaper.
"Look the cost of a text book. I don't know how much an author makes. Perhaps ten dollars a copy. But apart from the author there are a lot of people making money, including the paper mill, the transporter taking the paper, and so on. They are not adding much value."
New business models will also encourage take-up. Magazines and newspapers, in deep trouble because of the impact of the web, could bundle subsidised e-readers with subscriptions to electronic publications.
The book publishing industry is also beginning to feel the effect and needs new business models. "A book publisher might say I will give you this device and charge you £10 to£15 a month, and in return give you two or three books of your choice, and lock you into a two-year contract."
E-Ink is also trying to broaden its own market by encouraging the use of its screens in devices such as watches. But it biggest rival is not Apple, nor any other company. It is what Peruvemba calls "dead wood".
"Paper is awesome," he said. "It lasts 500 years. I don't think we will ever displace all paper." µ