| 摘要 |
PROBLEM TO BE SOLVED: To keep a speech without giving any effect onto a battery of a vehicle when an ignition of the vehicle is turned off during the speech. SOLUTION: A external power switch 8 is provided between a battery section 5 and an external power supply 9 in this portable telephone set 1 when an ignition is turned off, the external power switch 8 is open to allow the battery section 5 to supply power to the internal section. Then a control section 2 identifies whether a state is a speech state or an operation state, and in the case of the speech state or the operation state, the speech operation is maintained. When not, the control section 2 requests power-off to a power control section 6 to turn off power supply from the battery section 5 to the portable telephone set 1. In the case of ignition OFF, the speed or the operation is continued without imposing a load onto a vehicle battery 12.
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