Amorphous antipilferage marker

• US 4,495,487 A
• Filed: 10/27/1982
• Issued: 01/22/1985
• Est. Priority Date: 11/02/1981
• Status: Expired due to Fees

• Current Assignee: Allied Corp. (Honeywell International Inc.)
• Original Assignee: Allied Corp. (Honeywell International Inc.)
• Inventors: Kavesh, Sheldon, Sellers, Gregory J., Witte, Wayne H.
• Primary Examiner(s): Swann, III, Glen R.
• Application Number:
  US06/437,073
• Time in Patent Office: 818 Days
• Field of Search: 340/572, 340/551, 335/296, 324/201, 324/260
• US Class Current: 340/572.2
• CPC Class Codes: C22C 45/02 with iron as the major constituent
• CPC Class Codes: G08B 13/24 by interference with electromagnetic field distribution
• CPC Class Codes: G08B 13/2442 Tag materials and material properties thereof, e.g. magnetic material details
• CPC Class Codes: H01F 1/15308 based on Fe/Ni H01F1/15325 takes precedence
• CPC Class Codes: Y10S 428/928 Magnetic property

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 having a composition defined by the formula Fe_a Cr_b C_c P_d Mo_e Cu_f B_g Si_h where "a" ranges from about 63-81 atom %, "b" ranges from about 0-10 atom %, "c" ranges from about 11-16 atom %, "d" ranges from about 4-10 atom %, "e" ranges from about 0-2 atom %, "f" ranges from about 0-1 atom %, "g" ranges from about 0-4 atom % and "i" ranges from about 0-2 atom %, with the proviso that the sum (c+d+g+h) ranges from 19-24 atom % and the fraction [c/(c+d+g+h)] is less than about 0.84.

Claims

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 comprising an elongated, ductile strip of amorphous ferromagnetic material having a composition consisting essentially of the formula Fe_a Cr_b C_c P_d Mo_e Cu_f B_g Si_h where "a" ranges from about 71-79 atom %, "b" ranges from about 0-10 atom %, "c" ranges from about 13-15 atom %, "d" ranges from about 4-7 atom %, "e" ranges from about 0-2 atom %, "f" ranges from about 0-0.1 atom %, "g" ranges from about 0.5-2 atom % and "h" ranges from about 0-2 atom %, with the proviso that the sum (c+d+g+h) ranges from 19-24 atom % and the fraction c/(c+d+g+h) is less than about 0.84.

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

said marker comprises an elongated, ductile strip of amorphous ferromagnetic material having a composition consisting essentially of the formula Fe_a Cr_b C_c P_d Mo_e Cu_f B_g Si_h where "a" ranges from about 71-79 atom %, "b" ranges from about 0-10 atom %, "c" ranges from about 13-15 atom %, "d" ranges from about 4-7 atom %, "e" ranges from about 0-2 atom %, "f" ranges from about 0-0.1 atom %, "g" ranges from about 0.5-2 atom % and "h" ranges from about 0-2 atom %, with the proviso that the sum (c+d+g+h) ranges from 19-24 atom % and the fraction c/(c+d+g+h) is less than about 0.84.

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 comprising an elongated, ductile strip of amorphous ferromagnetic metal having a composition consisting essentially of the formula Fe_a Cr_b C_c P_d Mo_e Cu_f B_g Si_h where "a" ranges from about 71-79 atom %, "b" ranges from about 0-10 atom %, "c" ranges from about 13-15 atom %, "d" ranges from about 4-7 atom %, "e" ranges from about 0-2 atom %, "f" ranges from about 0-0.1 atom %, "g" ranges from about 0.5-2 atom % and "h" ranges from about 0-2 atom %, with the proviso that the sum (c+d+g+h ranges from 19-24 atom % and the fraction c/(c+d+g+h) is less than about 0.84, said marker being 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.