Green IT Toolkit

Why disappearing ink isn't just for spies

Tags:
Readers,
Displays,
Paul,
Canada

Nick Hampshire ZDNet.co.uk

Published: 13 Nov 2007 16:46 GMT

...is required. Third, paper is used, unlike the Toshiba system which uses sheets of PET — the type of plastic used in drinks bottles — and costs over $5 per sheet. Sheets of special coated paper for the Xerox system will cost little more than an ordinary sheet of paper.

In environmental terms this is a very attractive concept. Not only does the technique use no toner, itself a source of pollution in the office, but re-imaging a sheet of Xerox erasable paper takes only about 200 Joules, so every re-use can save an enormous amount of energy. With 30 to 100 re-uses per sheet, this represents a very large saving in energy.

The Xerox erasable paper, or "transient paper" as the company prefers to call it, is simply an ordinary sheet of printer paper that is coated with a thin layer of a special chemical that changes from transparent to black when exposed to light of a certain frequency. This paper is not only cheap to produce, but it can also be pre-printed with coloured letter-headings, logos and so on.

So the Xerox transient paper looks and feels like an ordinary sheet of photocopied or laser printed paper, although the print is more grey than black. The difference, of course, is that the print will completely disappear within 16 to 20 hours of printing, leaving just the original blank sheet of paper that can then be re-used to print another document.

"Transient paper has added security uses. You can imagine that even if you had left your document out in the open in the office, by mistake, then by the next day there'd be nothing on it, so if you had left sensitive data lying about you'd know it wouldn't be there by morning," says Xerox's Paul Smith.

Printing transient documents will require a special printer, and Xerox has developed and demonstrated prototype units that incorporate a special optical print head, which can deliver the pixel-sized dots of light needed to print an image.

The print will disappear within 16 to 20 hours of printing, leaving just the original blank sheet of paper that can then be re-used

Another useful feature of the printer/copier mechanism is that it can be used to erase text. Rather than waiting for the print on a page to disappear naturally, the page can be fed back into the machine where it will be erased and made available for immediate use. More impressively, the system can be used to erase and correct a specific typo on a page, a great feature if you have ever printed out 100 copies of a document and then noticed a serious mistake.

According to Paul Smith, the researchers have considered people's need to annotate documents and have produced a special pen with a light head that will allow hand-written notes to be created on any sheet of transient paper. These notes, like the printed text being annotated, will disappear after 16 hours.

Has transient paper arrived too late?
Xerox is at pains to point out that its transient paper technology is not yet commercially available, and no decision has been made as to when it will be marketed, if at all.

Indeed, some industry analysts believe that given the rapid development of flexible e-paper display technologies, the Xerox product is 10 years too late, and will be obsolete before it comes to market.

Electronic alternatives to traditional paper and printer technology are already under development, such as document reader devices.

These devices will use an electrophoretic display technology developed by E-Ink that generates a high-contrast image that, like paper, is readable in ambient light conditions. With a resolution of 170dpi, such electrophoretic e-paper displays offer a reading experience that is not dissimilar to reading conventional newsprint and, unlike the LCD displays used in laptops, will not require the use of a backlight.

Early generations of reader devices using rigid electrophoretic e-paper displays are now in production, the best known is probably the Sony PRS-500, which is currently available only in the US and Japan. Another well-known device is the Iliad Reader from Irex Technologies of the Netherlands.

Irex Technologies is already targeting paper replacement as an application for their reader, and to facilitate this it has incorporated a PDF viewer into the device, which allows the display of any PDF document downloaded into it. The device even incorporates a wireless stylus that allows the user to annotate documents.

Using the Iliad's USB docking connector, it is possible to quickly and easily download several thousand PDF pages from a PC to the reader. Once stored...