Meto International Gmbh

Walker Magnetics Group, Inc.

Braillon Magnetique, Societe Anonyme

Braillon Magnetique

Parc D'activites De La Grande Ile

Pierre Doyelle

Michael Rapp

Jean-Michel Gambut

Delphin Sibue

Fernand Buisson

A method and device for activation of large quantities of security elements for the electronic article protection. The security elements are exposed to at lease one magnetic field produced by one or more coils carrying a line current subjected to sine oscillations. The coils are supplied with current pulses that are shorter than the sine oscillations. The amplitude of the current pulses diminishes as a function of time.

Method and device for the activation of large quantities of security elements for the electronic article protection

A method and device for activation of large quantities of security elements for the electronic article protection. The security elements are exposed to at least one magnetic field produced by one or more coils carrying a line current subjected to sine oscillations. The coils are supplied with current pulses that are shorter than the sine oscillations. The amplitude of the current pulses diminishes as a function of time.

A holder having at least one magnetizable body surrounded by a coil is demagnetized by passing through the coil a succession of groups of pulses. The pulses of each group are of the same polarity and the polarity of each group of pulses is opposite that of the preceding group while the current of the pulses of each group is less than that of the pulses of the preceding group. Each group has 2 to 8 identical pulses and the pulses are formed by clipping an incoming alternating-current line voltage.

Demagnetizable electropermanent magnetic holder

A magnetic grab has a pair of vertically elongated magnetic pole pieces each having an upper end and a lower end. The pole pieces diverge downward symmetrically with respect to a vertical symmetry plane with the upper ends substantially more closely spaced than the lower ends. A plurality of nonmagnetic elements fixed to the pole pieces secure same together and a generally cylindrical rotor engaged between the pole pieces and centered on and rotatable about a rotor axis extending horizontally parallel to and between the pole pieces is formed by a pair of soft-iron bodies one of which is substantially thicker in a direction transverse to the axis than the other. One or more permanent magnets are sandwiched between the bodies and polarized generally diametrically of the rotor axis. The rotor can be turned between an active position with one of the bodies juxtaposed with one of the pole pieces and the other body juxtaposed with the other pole piece and one of the bodies lying mainly to one side of the plane and the other body lying mainly to the other side of the plane and an inactive position with the plane generally bisecting both bodies and each body closely juxtaposed with both pole pieces.

Permanent-magnet grab

In the magnetic chuck disclosed herein, a pair of elongate pole members are arranged to provide magnetic contact with a workpiece along parallel lines and thus are somewhat in the nature of rails. Preferably, the ends of the poles are segmented and provide for height adjustment to accommodate workpieces which are not entirely flat. The pole members extend along the sides of an elongate base plate with a space therebetween. Interposed between each pole member and the base member is a relatively thin layer of permanent magnetic material which resists de-magnetation. A switchable permeable magnet is provided between the pole members above the base plate and this latter permanent magnet is surrounded by a coil which allows the polarity of its magnetism to be switched so that it either aids or opposes the thin magnetic layer in polarizing the pole ends.

Magnetic rail chuck

A magnetic grab has a pair of pole pieces each forming a downwardly directed pole and formed adjacent the respective poles with horizontally extending semicylindrical seats having approximately the same center of curvature and open concavely inward toward each other. One of the pieces has an upwardly directed upper surface to one side of the seats and the other piece has a lower surface directed downward at the upper surface and also to the one side of the seats. A rotor fitting in the seats is provided with a plurality of high-flux rotor magnets polarized about respective axes extending generally diametrically of the rotor axis. At least one low-flux permanent magnet having a vertical polarization axis between the upper and lower surfaces has its north pole engaging one of the surfaces and its south pole engaging the other surface. The rotor can be turned about its axis between an inactive position with the north poles of the rotor magnets turned toward the seat of the piece having the other surface and the south poles of the rotor magnets turned toward the seat of the piece having the one surface, and an active position with the north poles of the rotor magnets turned toward the seat of the piece having the one surface and the south poles of the rotor magnets turned toward the seat of the piece having the other surface.

Growing community of inventors

Montmelian, France

Pierre Doyelle