Security system having deactivatable security tag

• US 5,442,334 A
• Filed: 07/20/1992
• Issued: 08/15/1995
• Est. Priority Date: 07/20/1992
• Status: Expired due to Fees

• Current Assignee: Stoplift Incorporated
• Original Assignee: Stoplift Incorporated
• Inventors: Sardinha, Mark P., Tebano, Riccardo, Gallo, Frank F., Bielek, Yan P.
• Primary Examiner(s): Peng, John K.
• Assistant Examiner(s): MULLEN, THOMAS J
• Application Number:
  US07/915,310
• Time in Patent Office: 1,121 Days
• Field of Search: 340/572, 340/551, 156/272.2, 156/274.2, 427/457, 427/504
• US Class Current: 340/572.3
• CPC Class Codes: G08B 13/242 Tag deactivation
• CPC Class Codes: G08B 13/2437 Tag layered structure, processes for making layered tags
• CPC Class Codes: G08B 13/2442 Tag materials and material properties thereof, e.g. magnetic material details

Abstract

A security system including a security tag for attachment to an article sold in a retail establishment, the security tag being formed with a coil having a tuned resonant frequency. The coil is formed of a composition of materials that includes a flake-like conductive metal that is intermixed with a resin, solvent and additives to define a paste-like composition that is adhered to a substrate in a coil configuration. A neutralizer device is formed as part of the security system and is operated to produce a high intensity magnetic field that emits eddy currents for melting the coil and thereby disabling the security tag when the tag is placed in close proximity thereto.

Claims

1. A security system having a security tag that is applied to an article located for sale in a retail establishment, said tag comprising a substrate that is formed of a non-conductive material and that includes opposed parallel surfaces, a coil having electrical conductive characteristics and being imprinted on one of said surfaces of said substrate, and a capacitor having portions respectively imprinted on said opposed surfaces of said substrate, said capacitor being electrically connected to said coil, wherein said coil and said capacitor define an electrical circuit having a predetermined single tuned resonant detection frequency and being responsive to a swept radio frequency signal transmitted at said predetermined tuned detection resonant frequency, wherein said circuit resonates to produce a signal that is detected by an alarm circuit, the material from which said coil and capacitor are formed including a plurality of separate particles having electrical conductive characteristics and that are disposed in electrical engaging relation, and a binder that is intermixed with the conductive particles for fixing the particles in said electrical engaging relation to provide for electrical continuity throughout said coil and capacitor, said binder comprising a resin that is selected from a group consisting of alkyd, epoxy, polyacryl, polyamid, polyurethane, polyvinyl acetate, hydrocarbon resin, nitrocellulose, polyvinyl chloride and rosin, said resin further including a copolymer comprising two or more monomers selected from a group consisting of acryl, vinyl, styrene, urethane, vinyl acetate and oil, said coil and capacitor being further responsive to application of a predetermined magnitude of induction heat thereto that results from the emission from a source of an electromagnetic field located in close proximity thereto for breaking down the electrical continuity of the conductive material in said coil and capacitor to increase the resistance thereof thereby inhibiting electrical conductivity therethrough.

2. A security system having a security tag that is applied to an article located for sale in a retail establishment, said tag comprising a substrate that is formed of a non-conductive material and that includes opposed parallel surfaces, a coil having electrical conductive characteristics and being imprinted on one of said surfaces of said substrate, and a capacitor having portions respectively imprinted on said opposed surfaces of said substrate, said capacitor being electrically connected to said coil, wherein said coil and said capacitor define an electrical circuit having a predetermined single tuned resonant detection frequency and being responsive to a swept radio frequency signal transmitted at said predetermined tuned detection resonant frequency, wherein said circuit resonates to produce a signal that is detected by an alarm circuit, the material from which said coil and capacitor are formed including a plurality of separate particles having electrical conductive characteristics and that are disposed in electrical engaging relation, and a binder that is intermixed with the conductive particles for fixing the particles in said electrical engaging relation to provide for electrical continuity throughout said coil and capacitor, said binder in said coil being formed of a resin, the composition of said coil further including a solvent, water and a plurality of additives having predetermined selected characteristics, said coil and capacitor being further responsive to application of a predetermined magnitude of induction heat thereto that results from the emission from a source of an electromagnetic field located in close proximity thereto for breaking down the electrical continuity of the conductive material in said coil and capacitor to increase the resistance thereof thereby inhibiting electrical conductivity therethrough.

3. A security system as claimed in claim 2, an additive in said composition having the characteristics of a defoamer that is utilized for preventing bubbling in the composition of said coil, said defoamer being selected from a group consisting of silicone based aryl-alkyd, modified methyl-alkyl-polysiloxane and non-silicone based 2,4,7,9-tetramethyl-5-decyn-4,7-diol.

4. A security system as claimed in claim 2, an additive in said composition having the characteristics of a dispersing agent for providing for dispersing of the conductive material in the composition of the coil, said dispersing agent being selected from a group consisting of polyethylene-oxide alkyl-aryl ether, dioctyl sodium sulfosuccinate and sodium alkylaryl polyether sulfonate.

5. A security system as claimed in claim 2, an additive in said composition having the characteristics of a leveling agent for providing for an even and glossy substrate surface for the coil composition, said leveling agent including polyether modified di-metyl-polysiloxanes.

6. A security system as claimed in claim 2, an additive in said composition having the characteristics of preventing marring of the substrate on which the conductive coil is adhered and being selected from a group consisting of polyether modified methyl-alkyl polysiloxanes, micronized low density polyethylene and micronized polytetrafluoroethylene.

7. A security system as claimed in claim 6, further comprising a slip additive used with said mar preventing additive and consisting of polyether modified polysiloxane copolymer.

8. A security system as claimed in claim 2, an additive in said composition having the characteristics of wetting the substrate and consisting of polyether modified methyl-ethyl-polysiloxanes.

9. A security system as claimed in claim 2, further comprising a thickener additive for forming the conductive coil composition in a paste-like material for application to said substrate and being selected from a group consisting of water-soluble polymers, including cellulosics, alkali-soluble acrylic polymer, alkali-swellable acrylic polymer, and associative thickeners.

10. A security system having a security tag that is applied to an article located for sale in a retail establishment, said tag comprising a substrate that is formed of a non-conductive material and that includes opposed parallel surfaces, a coil having electrical conductive characteristics and being imprinted on one of said surfaces of said substrate, and a capacitor having portions respectively imprinted on said opposed surfaces of said substrate, said capacitor being electrically connected to said coil, wherein said coil and said capacitor define an electrical circuit having a predetermined single tuned resonant detection frequency and being responsive to a swept radio frequency signal transmitted at said predetermined tuned detection resonant frequency, wherein said circuit resonates to produce a signal that is detected by an alarm circuit, the material from which said coil and capacitor are formed including a plurality of separate particles having electrical conductive characteristics and that are disposed in electrical engaging relation, and a binder that is intermixed with the conductive particles for fixing the particles in said electrical engaging relation to provide for electrical continuity throughout said coil and capacitor, said coil and capacitor being further responsive to application of a predetermined magnitude of induction heat thereto that results from the emission from a source of an electromagnetic field located in close proximity thereto for breaking down the electrical continuity of the conductive material in said coil and capacitor to increase the resistance thereof thereby inhibiting electrical conductivity therethrough, said source including means for transforming and rectifying line voltage to a rectified feed voltage having a range of 5 volts to 12 volts, means for adjusting said rectified feed voltage for introduction into a high voltage transformer, wherein a high voltage is obtained that has a range of 5,000 volts to 40,000 volts, and an emission coil electrically connected to said high voltage transformer and producing a high voltage electromagnetic field that produces induction heating in close proximity to said conductive coil for increasing the resistance therethrough.

11. A security system as claimed in claim 10, said means for adjusting said feed voltage including buffer units arranged in series for obtaining a pulsing effect and a plurality of parallel buffer units that increase the value of said feed voltage as it is introduced into said high voltage transformer.