| 摘要 |
PROBLEM TO BE SOLVED: To obtain an electricity supply method to a portable telephone from which a user can always reference only a telephone number memory and to obtain its electricity supply device. SOLUTION: When a residual capacity of a battery 9 is detected and its residual capacity reaches a setting value or below, power supply to other circuits than required circuit sections 5, 7, 10 to read and display a telephone number from a telephone number memory 13 is stopped. Since the telephone number directory function only is left, only a worst case that the electric residual amount is decreased to make the use of the portable telephone not available, resulting in disabling any communication can be avoided. This setting value is a voltage at which transmission reception processing can usually be difficult and a voltage at which the telephone function is substantially lost. The required circuit sections include the telephone number memory 13 and a display section 7 displaying the telephone number. Moreover, it is preferred that disabled transmission reception is displayed and that display of the telephone number can be made. |
