NTT DoCoMo's Solar Cell Mobile Phone Allows 5-Min Talk after 30-Min Charge

Oct 4, 2006 14:52 Motonobu Kawai, Nikkei Electronics

NTT DoCoMo, Inc. has exhibited a prototype mobile phone featuring a solar cell panel. If charged under the sunlight on a sunny day for 30 minutes, the mobile phone reportedly allows 5 minutes of voice communication. Its marketing schedule is yet to be determined.

The prototype is Mitsubishi Electric Corp.'s handset attached with Sanyo Electric Co., Ltd.'s solar cell on its back. The solar cell panel is initially folded, but opened when used to charge power. Due to the introduction of this solar cell, the back of the handset became about 5 mm thicker than before. The solar cell can acquire about 180 mW output with 100,000 lx, which is equivalent to the brightness of a sunny day. At the show, the company demonstrated an output of about 54 mW (14 mA, 3.9 V) by exposing the solar cell to 30,000 lx.

As a solar cell panel area was smaller, the prototype presented at the CEATEC show last year only allowed about 1-minute talk after 1-hour charge. According to DoCoMo, the company folded up a solar cell panel to expand its area by three times, while boosting its power conversion efficiency as well.

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