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:
Jul. 16, 1985
Filed:
Aug. 22, 1984
Northern Telecom Limited, Montreal, CA;
Abstract
A dynamic telephone receiver which is capable of being used in association with hearing aids, has a flux coil positioned around the pole piece and magnet assembly. To minimize the strong magnetic leakage field radiated from the air gap, which can attract pins, paper clips and other ferrous metals a shunt can be provided at the face of the receiver. However, this also shunts or at least severely attenuates the AC field produced by the flux coil for inductive coupling to hearing aids. The shunt of this invention shunts only the leakage flux from the air gap with minimal effect on the AC field from the flux coil. The shunt is in the form of a cup, with a central aperture in the front face, surrounded by an annular ring which is connected to the outer wall of the cup by narrow arms. The inner circumference of the ring is formed down towards the magnet to form a lip which attracts stray flux from the air gap. The shunt also acts to hold the receiver assembly together.