Piezoelectric electroacoustic transducer

DETAILED DESCRIPTION We claim: 1.
An electroacoustic transducer comprising a dielectric body centered on an axis and provided with a central plateau surrounded by an annular recess, an apertured dielectric cover overlying said body and forming a flat sound chamber therebetween, an elastic ring in said recess rising above said plateau, said cover being formed within said sound chamber with an annular rib registering with said ring, a piezoelectric membrane in said sound chamber having a rim clamped between said ring and said rib, and conductor means in said body for connecting said membrane in an electric circuit.
2.
A transducer as defined in claim 1 wherein said membrane comprises a metallic foil connected to said conductor means and a piezoceramic layer carried on the side of said foil confronting said plateau.
3.
A transducer as defined in claim 2 wherein said layer has a radius less than those of said rib and said ring.
4.
A transducer as defined in claim 1, further comprising a hollow dielectric base supporting said body.
5.
A transducer as defined in claim 4 wherein said body, said cover and said base consist of thermoplastic material.
6.
A transducer as defined in claim 5 wherein said body, said cover and said base are joined together by ultrasonic welds.
7.
A transducer as defined in claim 1 wherein said ring projects above said plateau by a distance representing a small fraction of the depth of said recess.
8.
A transducer as defined in claim 7 wherein said membrane divides said sound chamber into two compartments of approximately equal axial height.
9.
A transducer as defined in claim 8 wherein said cover has a central depression slightly increasing the height of the compartment remote from said plateau in the region of said axis.
10.
A transducer as defined in claim 1 wherein said ring has a cross-section converging to a narrow ridge in contact with said rim.




Description:
FIELD OF THE INVENTION Our present invention relates to an electroacoustic transducer for the conversion of sound waves into electric signals or vice versa, such as a microphone or a telephone receiver