| 摘要 |
PURPOSE:To rotate an apparatus efficiently by providing the central part of an ultrasonic vibrator with a protrusion and by causing resonance frequencies to coincide with each other through changing the length of said protrusion. CONSTITUTION:An ultrasonic motor stator is composed of longitudinal vibration exciting piezoelectric ceramics 1, torsional vibration exciting piezoelectric ceramics 2, and cylindrical ultrasonic vibrators 3-5. When AC voltage with the same frequency differing 90 deg. from each other in phase is applied to said ceramics 1, 2 of the stator, said stator becomes a longitudinal and torsional composite piezo-resonator and an elliptical vibration with both longitudinally and horizontally large amplitudes is induced in the end face A of said vibrator 3 and in the end face B of said vibrator 4. As a result, when a rotor is pressure-welded to said end faces A, B, it is possible to rotate said rotor efficiently. Further, when a protrusion 5 is provided and the length of said protrusion 5 is changed, two resonance frequencies of said longitudinal and torsional vibrations can be made to coincide with each other. |
