Theft detection apparatus and target and method of making same
First Claim
1. A magnetic type electronic theft detection apparatus comprising means for generating an alternating magnetic interrogation field in an interrogation zone, means for detecting magnetic response fields having predetermined characteristics in said interrogation zone and responder targets mounted on protected items which must be carried through said interrogation zone when taken from a protected area, said responder targets each comprising a length of drawn wire of an easily saturable magnetic material, heat treated, after drawing, to substantially increase its magnetic permeability.
4 Assignments
0 Petitions
Accused Products
Abstract
Items of merchandise (30) are protected from shoplifting or theft by affixing to them, special responder targets (32), which are formed by drawing a material of high magnetic permeability into a thin wire, then heat treating the wire to substantially increase its magnetic permeability and thereafter severing the wire into individual lengths. Several wires (32a, 32b and 32c) may be positioned on a common adhesively coated base strip (42) and covered by a peel strip (46) and wire like deactivation elements (48) of hard magnetic material may be positioned adjacent the wires for deactivating them.
52 Citations
29 Claims
- 1. A magnetic type electronic theft detection apparatus comprising means for generating an alternating magnetic interrogation field in an interrogation zone, means for detecting magnetic response fields having predetermined characteristics in said interrogation zone and responder targets mounted on protected items which must be carried through said interrogation zone when taken from a protected area, said responder targets each comprising a length of drawn wire of an easily saturable magnetic material, heat treated, after drawing, to substantially increase its magnetic permeability.
- 13. A responder target for use in a magnetic theft detection system of the type in which an alternating magnetic interrogation field is generated in an interrogation zone and magnetic response fields produced by a responder target passing through said interrogation zone are detected and, in response thereto, an alarm is actuated, said responder target comprising a drawn wire of easily saturable magnetic material, said wire being heat treated after drawing to substantially increase its magnetic permeability.
- 22. A method of manufacturing a responder target for use in a magnetic theft detection system of the type in which an alternating magnetic interrogation field is generated in an interrogation zone and magnetic response fields produced by a target passing through said interrogation zone are detected, and in response thereto an alarm is actuated, said method comprising the steps of drawing an easily saturable magnetic material into a wire, heat treating the drawn wire to substantially increase its magnetic permeability and cutting the wire into individual lengths.
Specification