| 摘要 |
PROBLEM TO BE SOLVED: To provide a portable telephone set, capable of surely supplying power required for at least a call or more in emergency. SOLUTION: A potable telephone device is provided with a main battery 9 and sub-batteries 10, 11. A controlling part 16 charges the sub-batteries 10, 11 alternately, when the residual charged capacity of the sub-battery 10 or 11 becomes a prescribed value or lower. It also charges the main battery 9, when the residual charged capacity of the main battery 9 becomes a prescribed value or lower and changes over to the main battery 9, after charging to use it as the power source in normal calls other than emergency calls. In addition, it changes over to the sub-batteries 10, 11 after charging, to use them alternately as the powder source. When the residual charged capacity of the main battery 9 becomes a prescribed value or lower and when an emergency cell switch 12 is turned on, it also changes over to the sub-batteries 10 or 11 to use either one of them as the power source. |
