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. 03, 1981
Filed:
Nov. 28, 1978
Applicant:
Inventors:
Assignee:
The Post Office, London, GB;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H04R / ; H04R / ;
U.S. Cl.
CPC ...
1791 / ; 29594 ;
Abstract
An electret transducer backplate is made of a thermo-softening plastics material rendered electrically conducting by electrically conducting particles distributed therethrough. An electret foil diaphragm is mounted on the backplate and the relative flexural rigidities of the diaphragm and the backplate are such that, in use, the deflection of the diaphragm is at least twenty times as great as the deflection of the backplate. A method of making the transducer involves heating an electret foil, bonding the electret foil to a retaining ring while the foil is hot and securing together the retaining ring and the backplate.