A vibration wave device having a resilient member, and electro-mechanical energy conversion means for inducing a travelling vibration wave in the resilient member, the travelling vibration wave being used as a drive source, includes means provided on at least one member of the vibration wave device at a location integer times or approximately integer times 1/2 of the wavelength of a vibration wave which may produce noise and making the dynamic rigidity of the member non-uniform.

Vibration wave motor

A device and method are provided for driving an ultrasonic motor. The motor's initial start drive frequency is set higher than the resonant frequency of the motor and an initial target drive frequency is set lower than the resonant frequency. A drive signal is then applied to a piezoelectric element on the stator in order to rotate the rotor. The frequency of the drive signals is then swept from the start frequency to the target frequency. Abnormal vibrations of the rotor that occur during sweeping of the drive frequency are detected by a monitor electrode mounted on the stator. Upon the detection of an abnormal vibration, the target frequency is reset to equal the drive frequency at which the abnormal vibration was detected. The drive frequency is then reset to a reset start frequency that is higher than the reset target frequency. Thereafter, the drive frequency sweeping step is repeated. This provides a high output from the motor without generating noise.

Circuit and method of driving an ultrasonic motor to method for driving an ultrasonic motor

In a vibration wave driven motor, an elastic body of an elliptic shape is provided where different degrees of stiffness or rigidity are available with the arcuate portions and the straight portions, and the ratio between the distortion energy and the vibration energy that part in the generation of the natural frequency for the A vibration mode is arranged virtually equal to that ratio for the B vibration mode, thus enabling the matching of frequencies for both A and B modes.

Vibration wave driven motor

An ultrasonic motor has a vibrating body polarized in a given direction. The vibrating body comprises a first piezoelectric body and a second piezoelectric body laminated to the first piezoelectric body in a preselected direction generally parallel to the polarized direction. Each of the first piezoelectric body and the second piezoelectric body has a first polarized portion and a second polarized portion. The first polarized portion of the first piezoelectric body is aligned in the preselected direction with the second polarized portion of the second piezoelectric body. The second polarized portion of the first piezoelectric body is aligned in the preselected direction with the first polarized portion of the second piezoelectric body. A movable member is frictionally driven by a combination of a stretching vibration and a bending vibration generated by applying a driving signal to the first polarized portions of the first and second piezoelectric bodies or to the second polarized portions of the first and second piezoelectric bodies.

Ultrasonic motor and electronic apparatus equipped with ultrasonic motor

A vibration wave motor for driving a movable member by a travelling vibration wave generated by applying a periodic signal to an electro-mechanical energy transducer element such as an electrostrictive device or piezoelectric device is disclosed. A drive status of the vibration wave motor is detected, a phase difference between the detected signal and the periodic signal applied to the transducer element is detected, a frequency of the periodic signal is selected such that the phase difference is equal to a predetermined constant and the vibration wave motor is driven in a resonance state.

A driving circuit for a vibration wave motor, in which a periodic voltage is supplied to electromechanical energy converting elements generates a travelling vibration wave in a vibrating member, thus causing a relative movement between the vibrating member and a movable member. For achieving effective operation of the vibration wave motor, the driving circuit controls the amplitude of the periodic voltage supplied to the electromechanical converting elements according to the drive state of the vibration wave motor.

Driving circuit for vibration wave motor

Disclosed is a driving circuit of a vibration wave motor in which a travelling vibration wave is generated in a vibratory member having a pair of driving electrostrictive element groups arranged or polarized in the fashion of a phase difference by a voltage being applied to the electrostrictive element groups, and the phase of an output signal put out by the vibration of the vibratory member being detected is shifted by a predetermined amount and the vibratory member is induced into a resonating state by the output signal being applied to the driving electrostrictive element groups and by an actuating pulse including a wide band frequency component being applied to the vibratory member particularly during the initial state thereof in which the vibratory member is not resonating.

Kho Ishizuka

Papers

Driving circuit for vibration wave motor

Driving circuit of a vibration wave motor