| 摘要 |
PROBLEM TO BE SOLVED: To realize stable driving, improve a driving force and driving efficiency and attain reduction in difference of individual performance by setting the resonance frequency of the first vibration mode higher than the resonance frequency of the second vibration mode. SOLUTION: An ultrasonic actuator 10 is composed of an elastic material 11, a couple of piezoelectric element 21, 22 joined on the elastic material and four driving force extracting members 31 to 34 formed at the lower surface. The elastic material 11 realizes matching of the expansion/compression movement of the first vibration mode and secondary flexure vibration of the second vibration mode by adequately setting the size of annular shape. After assembling of the ultrasonic actuator 10, adjustment is executed so that the relationship, resonance frequency of expansion/compression mode higher than resonance frequency of flexure vibration can be obtained. Composite vibration of flexure vibration and expansion/compression vibration may be generated by applying high frequency voltages A, B to a couple of piezoelectric elements 21, 22 to generate elliptical movement at the end portion of the driving force extracting members 31, 32. Thus, a driving force can be obtained. As a result, stable driving can be realized to improve driving efficiency and reduce difference of individual performances. |
