Murata Manufacturing Co., Ltd.

Hiroyuki Inami

Shuho Saito

Kazuaki Yamamoto

A piezoelectric electro-acoustic transducer has a substantially decreased resonant frequency without having to modify the size of a piezoelectric diaphragm or the shape of casing members used therein. The piezoelectric electro-acoustic transducer has a piezoelectric diaphragm including a metal plate and a piezoelectric ceramic disc disposed on one surface of the metal plate, wherein the piezoelectric diaphragm is to be supported at its periphery. A plurality of projections are specifically provided for stress transmission suppression at the periphery of the piezoelectric diaphragm in order to suppress or eliminate occurrence of circumferential transmission of a stress at the periphery during activation of the transducer.

Piezoelectric electro-acoustic transducer

A piezoelectric electro-acoustic transducer eliminates a negative influence caused by metal terminals upon the sound pressure and resonant frequency characteristics even when size and thickness reduction of the transducer are made. The transducer includes a piezoelectric diaphragm which includes a piezoelectric ceramic plate and a metal plate stored in a casing. The transducer also includes metal terminals in contact with the piezoelectric diaphragm and extending to the outside of the casing. The modulus of elasticity X of one metal terminal is specifically determined to be within a range defined by: ##EQU1## where E (N/m.sup.3) is the Young's modulus of one metal terminal in contact with a piezoelectric element, b (mm) is the width of part of the metal terminal extending from the inside of the casing to the outside thereof, h (mm) is the thickness of the metal terminal, and L (mm) is the length of the metal terminal.

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Toyama-ken, Japan

Hiroyuki Inami