| 摘要 |
PURPOSE:To perform a reduction in size and power conservation by specifying the structure and shape of a moving element and a vibrator without installing a position sensor and a feedback controller, and generating a standing wave on the vibrator thereby to form a stepwise operable ultrasonic motor. CONSTITUTION:A piezoelectric element 3 is provided at one side surface, a vibrator to be vibrated by the element 3, and a moving element to be rotatably driven by a frictional force in a contact state with the vibrator, are provided. The element 3 has a piezoelectric ring 30 in which piezoelectric elements 30a1-30b4 polarized in reverse directions on the front and rear surfaces are disposed. When AC voltages are applied to the element rows 30a1-30b4, a standing wave is induced at the ring to rotatably drive the moving element. Thus, the standing wave generated at the vibrator affects a stress to the noncontact part of the moving element thereby to stepwise drive the moving element. Accordingly, a conventional position sensor, a conventional feedback circuit are eliminated. |
