| 摘要 |
PURPOSE:To simultaneously drive a plurality of ultrasonic motors in parallel with a less number of parts by changing the pressing forces of stators press- contacted with rotors in corresponding to a temperature change produced when the ultrasonic motors are operated. CONSTITUTION:The optimum driving frequency for driving ultrasonic motors is set a little higher than an arbitrary first resonance frequency and lower than the frequency of an antiresonance point, for example, at 40kHz in a nonaudible band. Each ultrasonic motor 5 is constituted in such a way that a rotor 17 is press-contacted with a stator 11 constituted by alternately inverting single platy piezo-electric bodies 11 so that polarization can take place and elastic bodies 13 are firmly attached to one surfaces of the bodies 11 by means of a pressing mechanism 19. The rotor 17 is rotated by making the elastic bodies 13 to oscillate by causing the piezo-electric bodies 11 to exert an electrostrictive effect and, in addition, the resonance frequency can be adjusted by pressing the pressing mechanism 19 with a resonance frequency adjusting means 7. |
