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US 4,727,668 AGranted
Coded surveillance marker with improved biasing
AssigneeAllied Corporation
InventorsPhilip M. Anderson, Ronald K. Reich
Life of this patent
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Abstract
A surveillance marker is provided for utilization in antipilferage and anticounterfeiting systems. The marker includes a housing formed of barium ferrite impregnated plastic. Advantageously, the barium ferrite impregnated plastic housing provides a quasi-solenoidal dc magnetic bias field for activating one or more stacked ferromagnetic ribbons contained within the housing to produce an identifiable signal in response to an applied ac magnetic interrogation field.
Claims7
A surveillance marker for utilization in antipilferage, anticounterfeiting and like systems, comprising:
- ferromagnetic signal producing means comprising at least one strip of magnetostrictive ferromagnetic material;
- and
- combined housing and biasing means for said signal producing means formed of plastic impregnated with ferrimagnetic or ferromagnetic powder of relatively high coercivity;
- said high coercivity powder providing a quasi-solenoidal dc magnetic bias field for activating said ferromagnetic signal producing means to produce an identifiable singal in response to an applied magnetic interrogation field.
1 more element
Dependencies are inferred from the claim text.