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:
Feb. 04, 1986
Filed:
Sep. 21, 1984
John E Oldis, Belews Creek, NC (US);
Clayton L Nicholas, Indianapolis, IN (US);
AT&T Technologies, Inc., Berkeley Heights, NJ (US);
Abstract
An electret sheet is clamped on an apertured support around the aperture so that a sheet portion stretches all across the aperture. A tension-producing ring is advanced against the sheet portion normal to its stretch direction to produce progressively increasing tension therein. Concurrently, a loudspeaker on one side of the sheet emits constant-amplitude sound waves of fixed frequency and directed against the sheet portion to cause it to vibrate at that frequency. When, because of the increasing tension in the sheet portion, it's vibration amplitude rises to a predetermined value at or near resonance, the advance of the mentioned ring is ended, and the sheet portion is adhered to another ring which retains in that portion the tension then existing in it. Such tensioned sheet and adhering ring are then used to make electret diaphragms for electret microphones.