ahrooogah!! title for Digital Paper note
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section heading icon     digital paper

This page offers an introduction to what has been variously promoted as 'digital paper', 'electronic paper' and 'electronic ink'.

It covers -

It supplements the discussion of traditional paper (eg made from rag or wood pulp) and background material in the Electronic Publishing guide elsewhere on this site. The following page considers 'digital pens'.

section marker icon     background

Since the 1970s there have been major investments in research regarding new ways of displaying digital information and capturing information using a pen rather than a keyboard.

Although stylus-based personal digital assistants (PDAs) have gaining significant market acceptance - some studies suggest that 6% of the US online adult population has such a device, with most frequent use relating to 'smart phones' - work on 'electronic paper' has had little success.

Researchers have aspired to creation of a medium that has the essential characteristics of a sheet of paper - thin, light, flexible, shock-resistant, able to provide a high-resolution display of text and graphics, able to accept handwritten text, use little power and be highly durable. Have we forgotten anything else? Oh yes, have low production costs so that it could be priced as a 'throw-away' item.

So far the aspiration has been unfulfilled: most products meet several requirements of that wish list but not all.

section marker icon     Gyricon and SmartPaper

The prototype 'electronic paper' was developed at Xerox's Palo Alto Research Center (PARC), home of the computer mouse and laptop, in 1975. What's now marketed as SmartPaper was initially labelled 'Gyricon' (after the Greek for "rotating image"). It is currently handled by Xerox's Gyricon Media (GM) subsidiary.

Although the expectation was that it would replace many publications, with commuters for example uploading the daily newspaper onto a sheet of Gyricon for perusal en route to work, it's largely been restricted to corporate signage (particularly for upmarket US retailers).

The technology involves a flexible transparent membrane embedded with microscopic spheres, each with a light-coloured hemisphere and a dark-coloured hemisphere. Small electrical charges result in the spheres rotating to display their light or dark side up, thereby generating a high-contrast image
. The technology is 'display only' - the 'screen' does not accept input by pen or paw - and might more aptly be described as electronic cardboard. It's mono-chromal.

section marker icon     Electronic Ink

An independently-developed product using membranes containing black and white particles within microscopic liquid-filled capsules was developed in the late 1990s by E Ink, building on research at MIT.

As with SmartPaper, patterns are created by applying a small charge to the membrane. In essence, when the charge is applied white or black particles inside the membrane's capsules move to the top (ie screen-side) of those capsules, forming black and white patterns that look like ink on light gray paper. The 'ink' remains in position until a new charge is applied (eg when a 'page' is 'turned'), so there is no need for power to constantly refresh the image on screen. (E Ink is thus different to CRT and LCD screens.) E-Ink does not use a backlight, so that reading is dependent on ambient light, similar to a text on traditional paper. John Jacobson's 1997 paper offered an early explanation of the technology.

Like SmartPaper E Ink's Electronic Ink was initially primarily used for in-store displays. E Ink trademarked the term 'RadioPaper' and from 2003 apparently concentrated research into low-power lightweight
monochrome displays for personal assistants and laptops. Those displays have been used in electronic book device, such as the Sony Reader discussed here.

E Ink's site notes that an electronic ink display can have a much higher resolution than current LCD screens, uses 1/1000th of the power necessary for an LCD display and can preserve its content without power. A consumer for example could switch off the power on and off while reading a page of text. Sony reports that a prototype Reader in Japan has displayed the same page for three years on a single charge.

section marker icon     DataGlyphs and DigiPaper

Xerox developed but has not had much success with DataGlyphs, sometimes promoted as "digital paper." The technology essentially provides a watermark or steganographic identifier on wood-pulp paper. That identifier can be recognised by a scanning device.

Under optimal conditions a one-inch square DataGlyph could encode up to 1000 bytes of data. Promoters have claimed that it could be used in a document management system, as the basis of a security scheme (eg the image would be discernable to the scanner but not to the unaided eye if the document was photocopied) or as a barcode-style label in some form of production system.

While humans can write on DataGlyphs paper, that ink/pencil information rests on top of the 'glyph' and is independent of it.a form of encoded data designed to be printed on ordinary paper for later scanning and decoding by a computer.

Xerox PARC also developed DigiPaper, an image-based document representation that uses token-based image processing to obtain very high compression for bitonal images.

section marker icon     Anoto

For data capture the main contender is Anoto, developed in Sweden. It relies on specially-treated paper and the Anoto pen, a digital device that is tied to a wireless network. Each pen would have a separate IP address; each sheet of Anoto paper - whether sold as a label, a note pad or in some other format - will be unique. Putting pen to paper results in a unique map, that is then (in theory) transferred to and can be retrieved from a digital memory using the wireless network.

Sound excessively complicated? Perhaps. The idea grabbed the attention of geek-lifestyle magazine Wired in early 2001 and has attracted favourable attention from competitors such as the MIT Technology Review. In essence, Anoto is a 2001 wireless update of the graphics slates that appeared (and disappeared) in the late 1980s. It allows data capture - albeit second-hand - but otherwise is traditional paper: the display uses ink on pulp rather than digits on a screen.


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version of March 2007
© Bruce Arnold
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