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:
Sep. 07, 1982
Filed:
Jun. 25, 1980
Applicant:
Inventors:
Ronald Else, Martlesham, GB;
Michael A O'Sullivan, Ipswich, GB;
Assignee:
The Post Office, London, GB;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H01G / ;
U.S. Cl.
CPC ...
361233 ; 307400 ;
Abstract
In previously proposed arrangements for charging an electret foil the electret charge implanted varies over the area of the foil. In order to promote more even charging of the foil, the method of the invention subjects the foil to a progressively increasing electric field. One form of apparatus used to carry out the method has rollers at progressively higher potentials and electric fields are applied across the foil between these rollers and a metallized layer on the rear face of the foil which is earthed by a roller.