After several years of development, Fujitsu has improved its electronic paper technology to the point where it has begun exploring its commercial use in displays.

Several companies are developing such technology. The displays are made on sheets of plastic so the entire screen is flexible and lightweight. The technology requires no back-light or constant power supply to keep the image on the screen, making it highly energy efficient.

Fujitsu's latest displays were unveiled Wednesday and are on show at the Fujitsu Forum in Tokyo alongside prototype terminals that use the screens. Fujitsu unveiled an early prototype of the technology at the same show two years ago.

This year's e-paper screens are more impressive. The 12-inch and 8-inch screens can display 4,096 colors and completely refresh the on-screen image in about 2 seconds for an 8-color image, and 10 seconds for a 4,096-color image. They also have a higher resolution than the early prototypes, at 768 pixels by 1,024 pixels.

Fujitsu will target the screens initially at applications such as retail displays. The small and flexible screens could be attached easily to supermarket shelves and connected to a computer via a wireless network, so prices or information about special offers could be updated easily. The company hopes to offer the displays commercially by April 2008.

Fujitsu also showed some prototype tablet PC-like devices that use the flexible display screens as a way of providing longer battery life. Based on Windows CE, the tablet can run for 50 hours on a single charge, according to Fujitsu.

They include built-in wireless LAN support and a Web browser, and Fujitsu sees them being used to replace forms at banks or doctors' offices, for example. They are available to business customers now in sample quantities of 10, priced at $2,100 each for the version with a 12-inch screen and $1,400 each for the model with an 8-inch screen.

Despite the advances in the technology, a quick look at the displays suggests there is more work to do. The screen is refreshed in several sweeps, with each adding more color and detail, and could be faster to cut down on the wait time for each new image. The contrast ratio and brightness will also likely need to be improved for mass-market use, since they remain somewhat difficult to read.