PURPOSE: To increase the output torque of a mode rotating type ultrasonic motor which rotates a rotor by making metallic cylinders generate mode rotation of flexural oscillations and, at the same time, stabilize the operation of the motor. ;CONSTITUTION: A stator vibrator 2 is constituted of a pair of metallic cylinders 4 and 5 and piezoelectric elements 6 and 7 held between the cylinders 4 and 5. The cylinders 4 and 5 and elements 6 and 7 are tightly bound together with bolts passed through the cylinders 4 and 5. The elements 6 and 7 are polarized in the thickness direction and are constituted so that they can be driven by applying AC voltages which are orthogonal to each other in time and space across internal electrodes split into eight pieces in the peripheral direction. The cylinders 4 and 5 have slits 10 elongated in the axial direction so as to reduce the rigidity of the cylinders 4 and 5 in their peripheral directions. When the elements 6 and 7 are driven, the vibrator 2 makes flexural oscillations and the oscillation mode rotates in the peripheral direction. Therefore, a rotor 3 in press-contact with the end face of the vibrator 2 is rotated by a frictional force.;COPYRIGHT: (C)1995,JPO
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