Bell Telephone Laboratories

Joe Edward Warren

Alex Michael Brzezinski

John C Baumhauer, Jr

Stephen Reed Whitesell

An electroacoustic transducer in accordance with the present invention comprises a perforated backplate having a plurality of upstanding parallel ribs between which conductive surfaces are situated. The conductive surfaces are electrically interconnected with one another and with a contact surface on a relieved shoulder at one end of the backplate. This shoulder is engaged by a bifurcated contact spring that (1) electrically connects the conductive surfaces to the input of an integrated preamplifier circuit deposited on a substrate and (2) holds the substrate in place on the underside of the backplate. An electret diaphragm having a metallized surface is tensioned across the ribs of the backplate with the metallized surface facing away from the backplate, and while so tensioned, the ends of the diaphragm are clamped against the backplate by a conductive intermediate member that makes electrical contact with the diaphragm. The intermediate member is held in place by a conductive spring member that wraps around the sides of the foregoing assembly and presses the intermediate member and the substrate toward one another. The spring member provides the clamping force necessary to retain the desired tension on the diaphragm and at the same time further secures the substrate in place. In addition, the spring member includes a terminal that is located in engagement with the ground lead of the preamplifier circuit and thus in combination with the intermediate member provides a conductive path to ground for the conductive surface of the diaphragm. Finally, the spring member serves to provide additional electrostatic shielding for the electret.

Electroacoustic transducer with springs forming electrical

A transducer in accordance with the present invention includes a cylindrical housing that is open at one end and has an inwardly extending lip at the other end, a disc shaped membrane diaphragm being supported on the lip. An annular insulator rests on the periphery of the diaphragm, and a compressible annular spring member rests, in turn, on the insulator. In addition, a back plate having a central portion for engaging the diaphragm and a perimeter portion for engaging the spring member is positioned with the central portion in juxtaposition with the diaphragm and the perimeter portion resting on the spring member. The central portion extends from the perimeter portion, and the height of the central portion is less than the height of the insulator plus the height of the spring member prior to its being compressed and greater than the height of the insulator plus the final compressed height of the spring member. Means, such as a lock ring threaded into the open end of the housing, are provided to move the back plate toward the diaphragm and thereby compress the spring member.

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Indianapolis, IN, United States of America

Joe Edward Warren