Working displays have been on show for a while

The pioneers of digital paper and ink have unveiled a flexible prototype display that is a mere 0.3mm thick.

Massachusetts-based E Ink said the development of the ultra-thin display should greatly increase the potential uses of its technology.

The company speculates that the development could help drive the creation of computer screens that can be built into clothes.

Screen games

To make their thin electronic paper prototype the E Ink researchers used a steel foil thin film transistor. TFTs are often used to make screens for computers.

Laid down on top of the foil TFT is E Ink's patented material that is formed of millions of tiny capsules holding black and white pigment chips.

The technology works by trapping charged black and white pigment chips in tiny capsules between two electrodes. The electrode across the top of the capsule is transparent.

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A positive voltage across the upper electrode makes the black chips move to the top of the capsule and create a dark spot on the display's surface. Reversing the voltage brings the white chips to the top.

Using a TFT allows the E Ink researchers to apply voltages to precise areas of the display to create a relatively high resolution screen.

The resolution of the prototype is 96 pixels per inch and it is a total of 160 by 240 pixels in size.

The display can be refreshed in 250 milliseconds, too slow to display video, but fast enough to support something like a constantly updating electronic paper.

The flexible screen can survive being rolled into a tube 4mm in diameter.

Making electronic paper more flexible was likely to boost the places it can successfully be used, said E Ink researchers.

The creation of the thin electronic paper was detailed in a paper in the journal Nature.