Fujitsu has developed a prototype electronic paper screen that tackles one of the technology's biggest weaknesses: the amount of time it takes to refresh the image.

On electronic paper, screens like those used in Amazon.com's Kindle or Sony's Reader for electronic books, it typically takes a second or more to redraw the image on the screen. Sometimes the screen flickers a few times as the new image appears or, as in the case of Fujitsu's cholesteric LCD technology, the image is slowly revealed in a long sweep across the screen -- but it's a long way from the milliseconds required on other display screens.

To tackle this problem, Fujitsu has tried to confine the refresh to just the parts of the screen that need to be changed.

It works best in applications where touch-sensitive e-paper displays are used for things like electronic forms, as the company demonstrated at its Fujitsu Forum event in Tokyo on Thursday.

When a user checks a box or writes in a space on the form, only those rows or columns of the display that have changed are refreshed. Those areas are refreshed at the same speed as before, but because a much smaller area is changed, the user perceives an improvement in performance.

The working prototype was a 12-inch display (about the same size as an A4 sheet of paper) with 768 by 1,024 pixels (XGA) resolution.

Fujitsu has been developing electronic paper for several years, and last year began offering sample portable information tablets to customers in Japan that are based on e-paper and include a network connection.

E-paper displays offer several advantages over conventional LCD panels. They can be made almost paper-thin, are easy to read in bright light, and only use power when the on-screen image is being changed.