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:
Dec. 14, 1999
Filed:
Apr. 13, 1998
Dominic F Pignataro, Shrewsbury, MA (US);
Walker Magnetics Group, Inc., Worcester, MA (US);
Abstract
In the switchable magnet system disclosed herein, a central pole piece is backed by at least two permanent magnets having substantially different energies (H.sub.c) so that one of the magnets is relatively switchable or reversible and the other is not. A magnetically permeable frame provides a peripheral pole face at least on either side of the central pole face and a backing plate bridging the central pole piece over the permanent magnets. A coil surrounds the first and second permanent magnets inside of the peripheral pole face. According, energization of the coil in one direction can reverse the polarization of the first magnet, thereby effectively short circuiting flux produced by the second magnet and terminating holding, while energization of the coil in the opposite direction can polarize the first magnet in parallel with the second magnet, thereby to effect holding.