Patent ID: 8520869

Claim:
A piezoelectric acoustic transducer comprising: a housing having an opening formed in a wall surface; a plurality of diaphragms including at least a first piezoelectric diaphragm and a second piezoelectric diaphragm which vibrate in opposite phases by having a voltage applied thereto; at least one coupling member for coupling the first piezoelectric diaphragm and the second piezoelectric diaphragm with each other in a thickness direction; and a fixing member for fixing at least one of the first and second piezoelectric diaphragms to the housing, wherein one of the plurality of diaphragms is disposed in the opening of the housing so that a surface on one side faces outside the housing, and a surface on the other side faces inside the housing, the one of the plurality of diaphragms radiating a sound wave by vibrating at amplitude obtained by combining amplitude of the first and second piezoelectric diaphragms, each of the first piezoelectric diaphragm and the second piezoelectric diaphragm comprises a substrate and at least one piezoelectric element disposed on at least one of a front surface and a rear surface of the substrate, the piezoelectric element expanding or contracting by having a voltage applied thereto, and electric resistance is connected in series to the at least one piezoelectric element.