| 摘要 |
PURPOSE:To prevent lowering of driving efficiency by making a temperature change rate of oscillation frequency of an out put signal oscillated by an oscillator equal to that of resonance frequency of a piezoelectric body. CONSTITUTION:A driver for an ultrasonic motor 23 is equipped with a drive circuit 22, an oscillator 51 and a temperature characteristic corrective circuit 52, and drives piezoelectric bodies 1, 2 of the motor 23 by the drive circuit 22 according to an oscillation frequency of the oscillator 51. Said temperature characteristic corrective circuit 52 is composed of a temperature change detection circuit 35, a constant voltage source 38, an operational amplifier circuit 44 and a resistance 42, and the oscillation frequency f of said oscillator 51 changes a charge and discharge current to a capacitor 48 according to a temperature change so that said current is set to a given value. In this manner, if the temperature change rate and circuit gain of resistances 33, 34 are set appropriately, the temperature change rate of oscil lation frequency f of the oscillator 51 can be made equal to a temperature characteristic change rate of resonance frequency of the piezoelectric bodies 1, 2 and an always stable starting state can be obtained. |
