DoCoMo flirts with e-paper for phones

NTT DoCoMo engineers are tinkering with the use of e-paper for cell phones, hoping to develop a keypad that changes icons depending on which application is being used.

DoCoMo showed off prototypes of a phone with an e-paper keypad at the Ceatec exhibition in Chiba, Japan, this week. But the displays, from SiPix Imaging, are not yet ready for commercialization in phones, said Shuichi Aoki, an assistant manager in DoCoMo's Product Department who helped developed the phone.

The prototype phone, which has been in development for about one year, has a keypad that switches the display on each key from numbers to Japanese phonetic characters, called hiragana and katakana, depending on what application is being used. For example, when a user opens the e-mail client, the keypad switches from numbers to the phonetic characters, making them easier for users to see, Aoki said.

The technology will make using cell phones easier for users, particularly older people who may not be accustomed to using the devices, he said.

Before e-paper can be used in handsets, more work must be done to improve the technology. In particular, the response time of the e-paper display must be improved so that the symbols and icons used with each key change faster when switching between applications.

"It's a little too slow right now," Aoki said.

DoCoMo also wants to switch from using segmented e-paper displays to an active-matrix display for future prototypes. The current prototype uses a segmented e-paper display, which limits the display to pre-set characters, numbers, and symbols.

An active matrix display will allow any symbol or letter to be displayed, and allow applications to use their own, customized icons instead of drawing on a pre-determined list of available options, Aoki said.