Abstract: An ultrasonic motor is provided with a moving member and a vibrating member which is in contact with the moving member so as to provide the drive input for the moving member. A piezoelectric vibrator is attached to one side of the vibrating member and the opposite side of the vibrating member has a plurality of circumferentially arranged projections. A top section of each projection contacts the moving member. The piezoelectric vibrator will generate a travelling wave on the vibrating member when a proper alternating current electrical power source is applied to the vibrating member. The vibrating member would then be oscillated in a tangential direction, a normal direction, and a radial direction. The oscillations along the tangential direction and the normal direction generate the travelling wave and only the oscillation along the tangential direction is related to the rotational speed of the moving member.

Abstract: An ultrasonic motor comprises a stator, a rotor, a disc spring for generating a pressure between the stator and the rotor, and a stabilizer disc having a ring-shaped projection for distributing the pressure uniformly to the rotor along the circumference of the ring-shaped projection. Because of such uniform pressure distribution, greater output can be obtained.