Amorphous antipilferage marker

Abstract

A magnetic theft detection system marker is adapted to generate magnetic fields at frequencies that (1) are harmonically related to an incident magnetic field applied within an interrogation zone and (2) have selected tones that provide the marker with signal identity. The marker is an elongated, ductile strip of amorphous ferromagnetic material that retains its signal identity after being flexed or bent.

What is claimed is: 
     
       1. For use in a magnetic theft detection system, a marker adapted to generate magnetic fields at frequencies that are harmonically related to an incident magnetic field applied within an interrogation zone and have selected tones that provide said marker with signal identity, said marker being an elongated, ductile strip of amorphous ferromagnetic material and retaining its signal identity after being flexed or bent. 
     
     
       2. A marker as recited in claim 1, said marker having at least one magnetizable portion integral therewith, the magnetizable portion having coercivity higher than that of said amorphous material. 
     
     
       3. A marker as recited in claim 2, wherein said magnetizable portion is adapted to be magnetized to bias said strip and thereby decreases the amplitude of the magnetic fields generated by said marker. 
     
     
       4. A marker as recited in claim 2, wherein said magnetizable portion comprises a crystalline region of said material. 
     
     
       5. A marker as recited in claim 3, wherein said decrease in amplitude of magnetic fields generated by said marker causes said marker to lose its signal identity. 
     
     
       6. In a magnetic theft detection system marker for generating magnetic fields at frequencies that are harmonically related to an incident magnetic field applied within an interrogation zone and have selected tones that provide said marker with signal identity, the improvement wherein: a. said marker is an elongated, ductile strip of amorphous ferromagnetic material;   b. said marker retains its signal identity after being flexed or bent.   
     
     
       7. A magnetic detection system responsive to the presence of an article within an interrogation zone, comprising: a. means for defining an interrogation zone;   b. means for generating a magnetic field within said interrogation zone;   c. a marker secured to an article appointed for passage through said interrogation zone, said marker being an elongated, ductile strip of amorphous ferromagnetic metal capable of producing magnetic fields at frequencies which are harmonics of the frequency of an incident field;   d. detecting means for detecting magnetic field variations at selected tones of said harmonics produced in the vicinity of the interrogation zone by the presence of the marker therewithin, said selected tones providing said marker with signal identity and said marker retaining said signal identity after being flexed or bent. .Iadd.   
     
     
       8.  A marker as recited in claim 1, said marker comprising at least one crystalline phase and at least one amorphous phase. .Iaddend. .Iadd.9. A marker as recited in claim 1, said marker comprising an amorphous ferromagnetic strip provided with at least one magnetizable element. .Iaddend. .Iadd.10. A marker as recited in claim 9, said marker comprising a plurality of hard magnetic chips. .Iaddend. .Iadd.11. A marker as recited in claim 10, said marker comprising an ordered pattern of said plurality of hard magnetic chips. .Iaddend. .Iadd.12. A marker as recited in claim 11, said marker comprising at least one ordered row of said 
     
     
        plurality of hard magnetic chips. .Iaddend. .Iadd.13.  A marker as recited in claim 1, said marker comprising an at least 50% glassy ferromagnetic alloy of such ductility as to permit flexing or bending without degradation of the signal identity thereof. .Iaddend. .Iadd.14. A marker as recited in claim 13, said marker comprising an at least 80% glassy ferromagnetic alloy of such ductility as to permit flexing or bending without degradation of the signal identity thereof. .Iaddend. .Iadd.15. A marker as recited in claim 14, said marker comprising an amorphous ferromagnetic foil adapted to be bent to a round radius, without fracture, as small as ten times the foil thickness thereof. .Iaddend. .Iadd.16. A marker as recited in claim 1, said marker comprising a solid solution of said amorphous ferromagnetic material. .Iaddend. .Iadd.17. A marker as recited in claim 1, said marker comprising a ribbon or foil, wire, or sheet. .Iaddend. .Iadd.18. A marker as recited in claim 17, said marker 
     
     
        comprising a ribbon or foil. .Iaddend. .Iadd.19.  A marker as recited in claim 17, said marker comprising a wire. .Iaddend. .Iadd.20. A marker as recited in claim 17, said marker comprising a sheet. .Iaddend. .Iadd.21. An article of merchandise having an amorphous antipilferage marker secured thereto, said marker comprising that as recited in claim 1. .Iaddend. .Iadd.22. An article of merchandise as recited in claim 21, comprising book, wearing apparel or appliance. .Iaddend.