A METHOD OF MEASURING THE VIBRATION LEVEL DEPENDENCE OF IMPEDANCE-TYPE EQUIVALENT-CIRCUIT CONSTANTS

In piezoelectric transducers with high electromechanical coupling and finite dielectric loss angle, the mechanical quality factor of the transducer resonating under the short-circuit condition of the electric terminal is usually lower than that under the open-circuit condition. This fact is well explained by the impedance-type improved equivalent circuit including the effect of dielectric loss. This circuit is available for design of high power ultrasonic devices. A method of measuring the vibration level dependence of the impedance-type circuit constants is described and some experimental results are shown.