The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 02, 1994
Filed:
Feb. 18, 1992
Elmer V Carlson, Prospect Heights, IL (US);
William J Ballad, Buffalo Grove, IL (US);
Knowles Electronics, Inc., Itasca, IL (US);
Abstract
A tiny electret assembly for an electroacoustic hearing aid transducer, either a microphone or a sound reproducer, includes a thin, flexible, planar diaphragm and a planar backplate, the diaphragm and the backplate constituting the electret electrodes. One of the two electrodes is permanently charged to a given differential voltage relative to the other and the two electrodes are mounted, in the transducer, in fixed, spaced, substantially parallel relation to each other; the differential voltage between the electrodes pulls a central portion of the diaphragm toward the backplate, tensioning and stiffening the diaphragm. The mount for the diaphragm permits movement of the diaphragm rim in the plane of the diaphragm but precludes movement of the rim of the diaphragm perpendicular to the plane of the diaphragm (and the backplate) so that the diaphragm cannot buckle. Different rim mounts for the diaphragm are described.