Minnesota Mining and Manufacturing Company

Samuel Montean

Earl B Hoekman

Eugene C Heltemes

A dual-status marker for use in electronic article surveillance systems having an alternating magnetic field within an interrogation zone. The marker comprises a piece of a high permeability, low coercive force magnetic material substantially coextensive with a piece of remanently magnetizable material. The first piece is rectangular and exhibits lengthwise sections at which the material is removed, thus leaving narrow width regions forming switching sections, portions adjacent each end forming flux collectors. The marker is desensitized by uniformly magnetizing the piece of remanently magnetizable material.

Collector type article surveillance marker with continuous keeper

A multiple magnet assembly for magnetizing a magnetizable element of a desensitizable electromagnetic article surveillance marker, in which each successive assembly provides at a working surface a magnetic field of the same polarity but decreasing intensity. Any demagnetization effect attributable to reverse or back fields associated with one assembly are overcome by magnetization produced by a subsequent assembly, thus allowing markers having magnetizable elements with significantly different coercivee forces to be magnetized by the same apparatus.

Multiple magnet assembly for use with electromagnetic article

A multi-directionally responsive, dual-status marker for use in electronic article surveillance systems having an alternating magnetic field within an interrogation zone. The marker comprises a piece of a high permeability, low coercive force magnetic material substantially coextensive with a piece of remanently magnetizable material, in which the first piece is configured to exhibit at least two elongated responsive areas adjacent to edges of the piece perpendicular to each other, each area having a narrow width region forming a switching section and adjacent extensive regions forming flux collectors. In a preferred embodiment, the inner edges of all of the regions are defined by a narrow band of removed material, the remaining material in the center thereby being magnetically isolated from the responsive areas. The marker is desensitized by uniformly magnetizing the pace of unmagnetizable material.

Multi-directionally responsive, dual-status, magnetic article

A dual status magnetic marker for use in electronic article surveillance systems, in which a piece of low coercive force, high permeability material is positioned adjacent to a piece of remanently magnetizable material. The first piece is configured such that no characteristic response is produced when the magnetization of the entire piece is reversed by an alternating magnetic field in an interrogation zone, and when the second piece is magnetized with a predetermined pattern a localized field is provided which biases portions of the first piece, keeping those portions from reversing when the marker is in the interrogation field. The predetermined pattern is such that the remaining, unbiased portion of the first piece has a configuration capable of producing a characteristic response when the magnetization in that portion is reversed.

Dual-status, magnetically imagable article surveillance marker

A marker for use in radio frequency electronic article surveillance systems where the marker contains an inductive-capacitive resonant circuit and is made reversibly deactivatable and reactivatable by the addition of a piece of magnetic material and means, such as a piece of permanently magnetizable material, for biasing the first material to prevent alternating fields induced therein from changing the magnetic state of that material, thereby preventing hysteresis losses from causing a lowering of the Q of the resonant circuit below the point of detection.

RF reactivatable marker for electronic article surveillance system

A magnetic marker for use with electronic article surveillance systems in which a very high order harmonic response is obtained with postage-stamp sized pieces of high permeability material shaped to have a narrow switching section within which flux is concentrated by larger sections on each end of the switching section, the concentrated flux being sufficient to result in a high harmonic response.

Magnetic marker having switching section for use in electronic article

A marker adapted to be used with cloth or fabric articles to enable the detection thereof in an electromagnetic article surveillance system within which the marker generates a detectable signal related to an alternating electromagnetic field applied within an interrogation zone, wherein the marker comprises an elongated strip of amorphous ferromagnetic ribbon sealed on all major surfaces within flexible polymeric cover layers having a low rate of water vapor transmission, and a high degree of thermal stability, puncture resistance and conformability, such that the articles having the marker included therein may be subjected to repeated flexing and high temperature and humidity conditions such as encountered in commercial laundry operations without affecting the magnetic properties of the marker, while also not appreciably stiffening the article itself, thus being readily attached to or concealed therein.

Flexible ferromagnetic marker for the detection of objects having

A desensitizer apparatus for use with magnetically based electronic article surveillance systems having a marker containing at least one magnetizable section which when magnetized, alters the response of the marker produced by an alternating magnetic field provided in an interrogation zone. The apparatus includes a magnet assembly having an elongated permanent magnet section and a pair of elongated pole pieces which concentrate external fields produced by the magnet sections near a gap extending the length of the magnet section, the external field near the gap being sufficient in intensity to magnetize the magnetizable section of a marker positioned proximate thereto, and being rapidly attenuated a short distance from the gap. Accordingly, magnetically sensitive articles such as prerecorded magnetic recording cassettes to which the markers are affixed are not affected.

Desensitizer for ferromagnetic markers used with electromagnetic article

A widely accepted type of antipilferage system provides in an interrogation zone a magnetic field which periodically alternates at a predetermined frequency. Such systems further include means for detecting very high order harmonics of the predetermined frequency such as result from the presence within the zone of a marker having non-linear electrical or magnetic properties. In the present invention, such a marker includes an asymmetrically shaped piece or pieces of low-coercive force ferromagnetic material, including a center section and flux concentrator sections at opposite ends of the center section. Such a marker enables the protection of objects having a maximum dimension which is less than the length of prior art 'open-strip' markers.

Growing community of inventors

Blaine, MN, United States of America

Samuel Montean