| 摘要 |
PURPOSE:To obtain the portable telephone set which facilitates the operation of keys even at a dark place and suppresses energy consumption at a minimum. CONSTITUTION:The portable telephone set is equipped with a timer circuit 51, touch sensor 52, photosensor 53 and LED 55. In the case of originating a call, a user picks up the telephone set based on the detection outputs of the touch sensor 52 and the photosensor 53 and only when the surrounding is dark, keys 31 and 32 are lighted up by the LED 55. In the case of terminating the call and having a call terminating request, the keys 31 and 32 are lighted up by the LED 55 according to time shown by the timer circuit 51 and the output of the photosensor 53. |
