CONTROL METHOD OF PROGRESSIVE-WAVE TYPE ULTRASONIC MOTOR

摘要

PURPOSE:To correct the displacement of a resonance point automatically by installing a temperature sensor to an annular-speed elastic body, etc., and turning the elastic body by frequency lowering in reverse proportion to the rise of output voltage from the sensor. CONSTITUTION:A temperature sensor 62 being mounted to an annular-shaped elastic body 11 and measuring the temperature of a vibrator including an annular-shaped piezoelectric body 12 is set up to an ultrasonic motor 61 in which a rotor 13 is turned by progressive-waves generated from the piezoelectric body 12 and the elastic body 11. Output voltage from the sensor 62 is input to a voltage-frequency converter(VFC) 63, and AC voltage V0 sinomegat generated and AC voltage V0 cosomegat, phase of which is phase-shifted by 90 deg. by a phase shifter 64, are applied to the ultrasonic motor 61. Consequently, the temperature sensor 62 generates voltage proportional to an elevating temperature owing to heat generation by the revolution of the motor 61, and transmits voltage over the VFC 63 as a voltage signal. Accordingly, frequency alters in response to a temperature change, thus oscillating the piezoelectric body 12 at frequency coinciding with resonance frequency varying by a temperature rise at all times.