At&t Bell Laboratories

Bell Telephone Laboratories

American Telephone and Telegraph Corporation

Harold J Hershey

Robert L Beecher, Ii

John C Baumhauer, Jr

Tommy L Poteat

Alex Michael Brzezinski

Robert S Zieles

Stephen Reed Whitesell

An electroacoustic transducer, primarily in the form of a capacitive microphone, for incorporation into a semiconductor substrate. The vibrating element comprises a largely nontensioned diaphragm, such as an epitaxial layer formed on the semiconductor substrate, so as to greatly reduce its mechanical stiffness. The substrate is etched away in the desired area to define the diaphragm and form an acoustic cavity. A continuous array of microscopic holes is formed in the backplate to cut down the lateral flow of air in the gap between capacitor electrodes. Narrow gaps made possible by the hole array allow low voltage diaphragm biasing. In at least one embodiment, the acoustic input can be provided through the air hole array. An acoustic port may be added to alter the frequency response of the device, and a back closure provided to act as a rear acoustic cavity and an EMI shield.

Integrated electroacoustic transducer

A transducer embodying the present invention is assembled on a discrete electrically conductive frame (100) that has been formed to provide both leads (120-140) and a backplate (110). An integrated circuit chip (200) is bonded to one of the leads, and a dielectric inner housing member (300) is molded about the backplate and the portion of the leads adjacent to it. The inner housing member encapsulates the chip, embraces the perimeter of the backplate, and provides a cylindrical opening (310) that extends on each side of the backplate. A conductive outer housing member (400) is subsequently molded about the perimeter of the inner housing member, and a spacer (500), electret diaphragm assembly (600), and conductive gasket (700) are sequentially positioned in the opening on one side of the backplate. Conductive front and back covers (800,900) are thereafter bonded to the outer housing to close the opening and to complete a conductive enclosure that provides electrostatic shielding for the transducer. In addition, electrical continuity is provided between a metalized surface on the electret diaphragm and the conductive enclosure by means of the gasket.

Electroacoustic transducer

A multiple pushbutton switch is disclosed in which each pushbutton actuator has a rotatable cam mounted thereon that interacts with one or more lockout members positioned alongside of the actuator in the same plane as the cam. The interaction between the cam and the lockouts is such that one group of the pushbutton actuators can be depressed simultaneously while a second group of the actuators are blocked from simultaneous depression with the first group. Furthermore, a pushbutton actuator can be shifted from one group to the other merely by rotating the cam thereon to a different position.

Multiple pushbutton switch

A switch is disclosed in which manual adjustment of a contact spring pileup is avoided by closely controlling the interaction between (1) the contact springs, (2) a movable actuator including a plurality of cam surfaces, each of which is associated with an individual contact spring, and (3) a frame for supporting the actuator. This is achieved by molding a cam follower to one end portion and a mounting element to the other end portion of each contact spring. The mounting elements of the contact springs are positioned in engagement with one another and are secured to the frame. The mounting elements serve to orient the contact springs at a particular angle with respect to one another and accurately locate the contact springs and thereby the cam followers with respect to the cam surfaces of the actuator. The cam followers in combination with the associated cam surfaces serve to locate and provide a predetermined bias to the contact springs.

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Indianapolis, IN, United States of America

Harold J Hershey