| 摘要 |
PROBLEM TO BE SOLVED: To reduce power consumption at the time of start and prevent damage of a driving circuit, by controlling the output of an AC signal for driving in order that an electric-mechanical energy transducer for driving may be gently charged at the time of start of a vibrating motor. SOLUTION: Monitoring a result obtained by a resistance element 49 and a differential amplifier 29, and preventing a detected current from exceeding a value, a microcomputer 21 gives a command to a 4-phase oscillator 22 in such a manner that width of input pulses at the time of starting is gradually increased. The 4-phase oscillator 22 gives a signal whose phase is shifted by 90 deg. to each of the switching elements 23-26. The elements 23-26 are switched and switch the primary side of a transformer whose one side is connected with a power source Vcc. The secondary side drives a vibration wave motor USM, with a voltage stepped up in accordance with the switching width. While the input current is monitored, the width of input pulses are gradually increased, so that a usual large current can be restrained to be small. |
