| 摘要 |
PROBLEM TO BE SOLVED: To inform the timing to turn off the back light of a display part or operating part to a user, and to prevent erroneous operation caused by the back light abruptly turned off. SOLUTION: The non-operating time of a key switch 3 is counted by a timer 2. When the non-operating time reaches a prescribed time, on the basis of information on a memory 11, the use state of a relevant terminal is discriminated by a microcomputer 1. Then, a current switching circuit 8 is controlled, and the luminance of a back light 6 is lowered corresponding to the use state. At such a time, the ON of a key back light 9 is maintained. Thus, the timing to turn off the back light 6 can be obtained by the user and erroneous operation in operation for turning on the back light again can be prevented. Further, since the back light is turned off in a use state, with which the ON of the back light is not required, power consumption can be reduced. |
