| 摘要 |
PURPOSE:To prevent driving speed and driving efficiency from lowering due to temperature rise by providing a temperature detecting means and means for controlling each frequency signal input to an ultrasonic oscillator in response to a detection signal from the temperature detecting means. CONSTITUTION:A frequency signal output from an oscillator 41 is split through a phase shifter 2 into two voltage signals having different phases which are then applied through amplifiers 43a, 43b on the electrode 26 of a first piezoelectric element 22 and the electrodes 27a, 27b of second piezoelectric elements 23a, 23b in order to drive an ultrasonic motor 30. Resilient body 21 of the ultrasonic oscillator 11 is provided with a thermocouple 50 connected with an operating circuit 51 and the frequency signal of the oscillator 41 is controlled in response to a detected temperature. Variation of resonance frequency due to temperature rise of the ultrasonic oscillator 11 is detected through the thermocouple 50 and the operating circuit 51 controls each frequency signal input to the ultrasonic oscillator. |
