THIN-PLATE PIEZOELECTRIC ELEMENT, PIEZOELECTRIC ACOUSTIC ELEMENT FORMED USING THE SAME, PIEZOELECTRIC VIBRATOR, PIEZOELECTRIC ACTUATOR, PIEZOELECTRIC TRANSFORMER, AND COLD-CATHODE FLUORESCENT LAMP PROVIDED THEREWITH

摘要

PROBLEM TO BE SOLVED: To obtain a thin-plate piezoelectric device which is lessened in thickness so as to be enhanced in device characteristics and reliability, by a method wherein a metal electrode and a piezoelectric material comprised in the thin-plate piezoelectric device are both specified in a relation between Young's modulus and thickness. SOLUTION: The product of the square of Young's modulus and thickness of metal electrodes 2 and 3 comprised in a thin-plate piezoelectric device is set 0.0516 times as large as that of the square of Young's modulus and thickness of a piezoelectric material 1. When the thin-late piezoelectric device is used for a circular piezoelectric acoustic device, the piezoelectric acoustic device is constituted through a manner where a thin-plate piezoelectric device composed of the piezoelectric material 1 as thick as 200μm or below and the metal electrodes 2 and 3 is bonded to a diaphragm 5 and housed in a resonant case provided with a sounding hole and mesh rear holes. A silver deposited film or a sputtered film is formed as thickness as 2μm or below, by which the piezoelectric acoustic device of this constitution is increased in sound pressure by 5 dB when an alternating current voltage of 1 V is applied. At this point, a radial electromechanical coupling factor is increased by 5% or so, and a dielectric constant is also increased by 10%.