Patent ID: 8503700

Claim:
A piezoelectric acoustic transducer, comprising: a chassis having a wall surface including an opening; a plurality of diaphragms including at least a first piezoelectric diaphragm and a second piezoelectric diaphragm which vibrate in phases opposite to each other when a voltage is applied to each of said first and second piezoelectric diaphragms; and a joint member which connects said first and second piezoelectric diaphragms in a positional relationship such that said first and second piezoelectric diaphragms are located at positions different from each other in a thickness direction, wherein one of said diaphragms is provided, in the opening of said chassis, so as to have one surface facing an outside of said chassis and another surface facing an inside of said chassis, the one of said diaphragms functions as a radiation plate which radiates a sound wave by vibrating at an amplitude generated by synthesizing amplitudes of said first and second piezoelectric diaphragms, and each of said first and second piezoelectric diaphragms includes: a substrate; and a piezoelectric element which is provided on at least one of a top face and a reverse face of said substrate, and expands or contracts when a voltage is applied to said piezoelectric element.