Impedance-type equivalent circuits of the piezoelectric vibrator for applications to ultrasonic motors and actuators.

The piezoelectric vibrator has been used at its resonance in general; therefore the equiv-alent circuits have been obtained as an admittance-type expression drawn from the input admittance developed near their resonance point. However, it may not neces-sarily be well for some piezoelectric devices, because they cannot yield a superior char-acteristic when used at the resonance frequency. On the other hand, vibrational char-acteristics of a piezoelectric ceramics vibrator only are proved experimentally to be good at its anti-resonance point. Therefore, the authors thoughthat the equivalent circuit of a piezoelectric vibrator should be expressed depending upon its anti-resonance, where it is called the B-type equivalent circuit. This paper deals with the equivalent circuits developed near the anti-resonance mainly depending upon the input impedance of the piezoelectric vibrator.