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:
Jan. 03, 1984
Filed:
Oct. 19, 1981
Applicant:
Inventors:
Assignee:
Northern Telecom Limited, Montreal, CA;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H04R / ;
U.S. Cl.
CPC ...
1791 / ; 179184 ; 179187 ; 179188 ; 307400 ;
Abstract
An electret microphone has a metal shield around it in order to guard against electromagnetic interference. Acoustic waves reach the electret element through a passage in the shield. The electret response is undesirably affected by an electric field produced by body capacitance when the microphone is brought close to a user's mouth. To overcome this effect, the microphone has a conductive film, transparent to acoustic waves, positioned between the passage and the electret element, the film contacting a grounded part of the casing. The conductive film can form an integral part of a microphone moisture barrier.