| 摘要 |
PROBLEM TO BE SOLVED: To provide a portable telephone set controlling the back light of an LCD and keys and incoming sound in accordance with detected periphery environment. SOLUTION: The portable telephone set has an oscillation part 1 generating an oscillation wave, an upper detection part 2 detecting the input level of the oscillation wave from the oscillation part, a comparison part 3 comparing the input level of the detected oscillation wave with a reference value, the back lights 9 emitting light, and a control unit 4 controlling the light emission of the back lights 9 based on a comparison result in the comparison part 3. The presence or absence of an obstacle on the face of the portable telephone set can be judged by the height of the input level of the oscillation wave, which is detected in the detection part 2. When the obstacle exists on the face of the portable telephone set, the consumption of power can be prevented by, for example, putting out the back lights 9 of LCD and the keys. |
