| 摘要 |
PURPOSE:To surely stop the actuation of an ultrasonic motor at a low cost when it is not possible to actuate the motor or when very difficult abnormality occurs. CONSTITUTION:A feedback circuit 16 controls the oscillation frequency of an oscillation circuit 10 so that the frequency of a drive signal supplied to an ultrasonic motor 14 from an output circuit 13 can gradually become lower to the optimum drive frequency of the motor 14 or its vicinity from an actuation starting frequency and the motor 14 can be actuated. When the motor 14 is not actuated by the actuating operation, a reset circuit 20 outputs a reset signal so as to make the actuating operations to be tried once more. A counter circuit 22 counts the number of outputting times of the reset signal from the circuit 20 and, when the count value exceeds a prescribed value, stops the actuation of the motor 14 by outputting actuation stop signals to the circuits 10 and 12. |
