PURPOSE: To prevent external adherence of oil, etc., in the case of frictional contact of a rotor with a stator by sticking a flexible sheet to an outer periphery of a rotor of an ultrasonic motor to surround pressure contact parts of the rotor with the stator.
CONSTITUTION: A flexible sheet 23 is so stuck to an outer periphery of a rotor 3 with adhesive 22 as to surround pressure contact parts of the rotor 3 with a stator 1. When a rodlike ultrasonic motor A receives a lens drive signal from a driving circuit, AC voltages are supplied from electrodes 10-14 to A-phase piezoelectric elements 5, 6 and B-phase piezoelectric elements 7, 8. Vibration is excited in two flat surfaces of a vibration elastic element 1 and a retainer 4 by vibrations generated at the elements 5-8. Further, since the vibrators have predetermined phase difference at timing due to a phase difference between various AC voltages, rotary motions occur on the surfaces of the element 1 and the retainer 4. As a result, the rotor 3 in contact with the element 1 is rotated, but external sticking of oil, etc., can be prevented.
Kawai Toru
Takashi Suzuki
Kashiwaha Seiichi
