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:
Jan. 21, 1992
Filed:
Jun. 01, 1990
Chester Piotrowski, St. Paul, MN (US);
Charles L Bruzzone, St. Paul, MN (US);
T050832716g-Long, St. Paul, MN (US);
Jerome W McAllister, St. Paul, MN (US);
Minnesota Mining and Manufacturing Company, St. Paul, MN (US);
Abstract
A marker for use in magnetic-type electronic article surveillance systems, comprising a substrate on which are deposited a plurality of high permeability, low coercive force magnetic thin-films, each being separated from an adjacent magnetic thin-film by a non-magnetic thin-film. Each of the magnetic films have substantially the same permeability and coercive force, and the non-magnetic films are of a thickness to allow magnetostatic coupling while inhibiting exchange coupling. Accordingly, all of the magnetic thin-films reverse as a single entity and produce a sharp, readily distinguishable response.