PIEZOELECTRIC TYPE ELECTROACOUSTIC TRANSDUCER FOR CONTROLLING DEFLECTING DIRECTION OF PIEZOELECTRIC VIBRATING PLATE

摘要

PURPOSE: A piezoelectric type electroacoustic transducer for controlling a deflecting direction of a piezoelectric vibrating plate is provided to reduce a change of a resonant frequency by forming protective layers on both surfaces of a piezoelectric vibrating plate and warping a front side of the piezoelectric vibrating plate. CONSTITUTION: A piezoelectric vibrating plate(1) includes a plurality of piezoelectric ceramic layers laminated on both sides of an internal electrode and a plurality of main surface electrodes provided on front and back side main surfaces of the piezoelectric vibrating plate. The piezoelectric vibrating plate is surface-flexural-vibrated in a thickness direction thereof when an AC signal is applied between the main surface electrodes and the internal electrode. A housing includes a supporter for supporting a back side of an outer circumference of the piezoelectric vibrating plate. A front protective layer(8) and a back protective layer(9) are formed on both surfaces of the piezoelectric vibrating plate. The piezoelectric vibrating plate is warped on a front side thereof by the hardening shrink stresses of the protective films.