Patent ID: 6888947

Claim:
A piezoelectric electroacoustic transducer comprising: an internal electrode; a substantially rectangular piezoelectric diaphragm including an internal electrode, a plurality of laminated piezoelectric ceramic layers having the internal electrode interposed between two of the piezoelectric ceramic layers, principal-surface electrodes disposed on top and bottom principal surfaces of the piezoelectric diaphragm, wherein said piezoelectric diaphragm generates surface bending-vibrations in response to application of an alternating signal between the principal-surface electrodes and the internal electrode; a substantially rectangular resin film that is larger than the piezoelectric diaphragm and having the piezoelectric diaphragm affixed onto substantially a central portion of a front surface thereof; and a housing having the piezoelectric diaphragm and the resin film housed therein and having a support for supporting an outer periphery of the resin film onto which the piezoelectric diaphragm is not affixed; wherein the resin film is heat resistant to at least a reflow-soldering temperature; a perimeter of the resin film including four corners thereof is fixed to the support of the housing by adhesion; an area of the piezoelectric diaphragm is about 40% to about 70% of an area of a portion of the resin film which is not fixed to the support by adhesion; and the resin film has at least one undulated portion bending in front and rear directions thereof and disposed in the outer periphery thereof onto which the piezoelectric diaphragm is not affixed and inside the perimeter thereof which is fixed to the support by adhesion.