Sound generating apparatus with sealed air chamber between two sounding

Abstract

A sound generating apparatus using piezoelectric elements includes first and second sounding plates arrayed in parallel with each other. The first and second sounding plates respectively include first and second diaphragms, and first and second thin plate-like piezoelectric elements laminated onto the first and second diaphragms. The first and second sounding plates are coupled together at the outer peripheral portions by a ring, thereby forming a hermetically sealed internal air chamber. The first and second sounding plates coupled together by the ring, and containing the internal air chamber cooperate to form a sounding member. The sounding member is supported by means of four resilient supporting members made of, for example, rubber, in a housing. In the housing, a front air layer and a rear air layer are formed on both sides of the sounding member, respectively. The front and rear air layers communicate with each other through a ringlike sound path. A plurality of sound passing holes are distributed closer to the outer periphery portion, while confronting the front air layer. A drive circuit applies a drive voltage signal in parallel to the first and second sounding plates.