| 摘要 |
PURPOSE:To stabilize operation by using a spring, a spring constant of which in an applied-pressure allowable region is made smaller than that in regions lower than said region. CONSTITUTION:A section having the easy inclination of a characteristic curve is employed as a spring for pressure used for an ultrasonic motor in order to set a spring constant in an applied pressure allowable region at a value smaller than a spring constant in regions lower than the applied-pressure allowable region. Consequently, even when the set quantity of deflection is varied by the roughness, waviness and abrasion of the surface of a friction material 5, the change of. the applied pressure of a vibrator 3 and a moving body 7 is reduced. With said motor, the vibrator 3 is composed of an elastic body 1 and a piezoelectric body 2, and the moving body 7 consists of an elastic body 6 and the friction material 5. The vibrator 3 is fixed by a supporter 4, progressive waves are excited in the vibrator 3 when an AC field is applied to the piezoelectric body 2, and the moving body 7 is turned while using the excited progressive waves as the driving force. Accordingly, even when the set quantity of deflection is varied by the surface roughness, etc., of the friction material 5, the characteristic change of the motor is reduced. |
