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:
May. 10, 1977
Filed:
Mar. 03, 1976
Applicant:
Inventors:
Ryszard Kitajewski, Broxbourne, EN;
Anthony William Sweet, Bishops Stortford, EN;
Michael Philip Dyer, Old Harlow, EN;
Assignee:
International Standard Electric Corporation, New York, NY (US);
Attorneys:
Primary Examiner:
Int. Cl.
CPC ...
H04M / ;
U.S. Cl.
CPC ...
179 / ; 179 / ;
Abstract
A Hall effect device is employed in telephone exchange circuitry for detecting when a called subscriber goes off-hook. This is done by detecting when a DC current due to line looping is superimposed on the AC current due to ringing whereupon ring trip occurs. Also described are circuits in which after ring trip has taken place the Hall device continues to supervise the called line loop.