摘要 |
An ultrasonic motor includes a stator, which includes a piezoelectric element, and a rotor, which opposes the stator. The piezoelectric element vibrates the stator to rotate the rotor. The rotor has an annular thin section. An elastic ring is secured to the thin section. The mass of the elastic ring is selected from a predetermined range of masses. The motor speed at which a predetermined level of noise is produced by the motor is substantially constant for the range of the masses. This reliably damps undesirable vibration of the motor.
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