Seiko Epson has moved a step closer to its aim of producing electronic paper by developing a prototype microprocessor built on a flexible plastic base.

The ACT11 chip is an 8bit asynchronous microprocessor made of 32,000 low-temperature polysilicon TFTs (thin-film transistors) that sit on a flexible plastic substrate, according to the company.

The chip is 27x24mm and runs at up to 500kHz when operating at 5V. It is the first operational version of a microprocessor for processing data on "e-paper", said a company spokesperson.

Seiko Epson is working towards development of a display mounted on flexible plastic backing that will be 0.2mm thick. It plans to make A4 (297x210mm) foldable sheets that could substitute for business documents or be used as newspapers or books. The company wants to commercialize e-paper within the next five years.

However, there are many specifications and processes for the chip technology that Seiko Epson needs to improve before it can make e-paper, the spokesperson said.

While the chip is functional, the company won't say how many of them will be needed for data processing for sheets of e-paper.

"This is a research and development model and we have to work on its reliability. The technology is suitable for volume production, but we have yet to build the equipment for this," said the spokesperson.

To make e-paper, the company also has to integrate the low-temperature polysilicon TFTs with its OLED (organic light emitting diode) technology, which is another major program within the company, he said.

The chip is part of a number of programs that use inkjet technologies to make circuits and flexible screens on thin substrates. Last November Seiko Epson demonstrated an inkjet technology that prints circuits on a board 200 microns thick.

As well as e-paper, the combination of its TFT and OLED technologies could lead to the development of giant, peelable TV screens sometime after the end of the decade, according to the company.