Electronic anti-theft element

• US 6,262,663 B1
• Filed: 02/08/1999
• Issued: 07/17/2001
• Est. Priority Date: 08/06/1996
• Status: Expired due to Term

• Current Assignee: CHECKPOINT SYSTEMS, INC. (CCL Industries Incorporated)
• Original Assignee: CHECKPOINT SYSTEMS, INC. (CCL Industries Incorporated)
• Inventors: Lendering, Peter, Altwasser, Richard
• Primary Examiner(s): Lee, Benjamin C.
• Application Number:
  US09/147,646
• Time in Patent Office: 890 Days
• Field of Search: 340/572.5, 340/572.7
• US Class Current: 340/572.5
• CPC Class Codes: G08B 13/242 Tag deactivation
• CPC Class Codes: G08B 13/2437 Tag layered structure, processes for making layered tags

Abstract

An electronic anti-theft element consists of at least one spiral printed circuit, a capacitor and a dielectric layer arranged therebetween, or of two spiral printed circuits which are arranged on respective sides of a dielectric layer in an at least partially overlapping manner (forming resonant circuit). The object of the invention is to provide a resonant circuit which is less liable to be reactivated. For that purpose, in at least one selected area (a rated break point) of the dielectric layer a short-circuit is created between the opposite capacitor plates or spiral printed circuits when a sufficiently high energy is supplied by a magnetic alternating field. The selected area is locally reinforced, preventing the suppression of the short-circuit by mechanical stress and the reactivation of the anti-theft element.

Claims

1. A security element for electronic article surveillance, comprising:

a capacitor element;

at least one coiled conductive track; and

a dielectric layer arranged so as to overlap said at least one coiled conductive track at least in part, wherein the dielectric layer includes at least one selected area serving as a zone of preferred breaking in which a short circuit is produced between the opposed capacitor element and the at least one coiled conductive track by a supply of energy in a sufficiently high amount by an alternating magnetic field, and wherein the selected area is strengthened locally, such that a destruction of the short circuit by mechanical loads, and hence a reactivation of the security element are prevented.

2. The security element as claimed in claim 1, wherein the dielectric layer is of substantially uniform thickness and has uniform density.

3. The security element as claimed in claim 2, wherein the areas of overlap between said two coiled conductive tracks and hence the capacitance between said two coiled conductive tracks are concentrated at the inner ends of said two coiled conductive tracks.

4. The security element as claimed in claim 3, wherein the outer ends of said two coiled conductive tracks overlap in a small area and there is a relatively long area with no overlap adjacent to the outer ends of said two coiled conductive tracks.

5. The security element as claimed in claim 1, wherein two, at least partly overlapping, coiled conductive tracks are provided, being wound in opposite directions, with the selected area being located in the outer end areas of said two coiled conductive tracks where the induced voltage is at its highest level.

6. The security element as claimed in claim 5, wherein said dielectric layer is fabricated by one of a coating or a laminating process.

7. The security element as claimed in claim 5, wherein weak zones are provided on one or both sides of said selected area.

8. The security element as claimed in claim 7, wherein said weak zones are formed by narrowing down the width of said two coiled conductive tracks.

9. The security element as claimed in claim 7, wherein in said weak zones the dielectric layer is less strongly bonded to said capacitor element or said two coiled conductive tracks than in the remaining areas.

10. The security element as claimed in claim 7, wherein said weak zones are characterized in that the said two coiled conductive tracks are perforated.

11. The security element as claimed in claim 1, wherein the selected area is characterized in that the dielectric layer is thinner in said selected area than in the remaining areas.

12. The security element as claimed in claim 1, wherein the selected area is characterized in that the dielectric layer has in said area a different chemical or physical property than in the remaining areas.

13. The security element as claimed in claim 1, wherein the dielectric layer is comprised of at least two components.

14. The security element as claimed in claim 13, wherein the melting point of one component of dielectric layer lies above the production temperature for security elements.

15. The security element as claimed in claim 1, wherein two coiled conductive tracks are provided, with at least one coiled conductive track defining a strong zone, and wherein the strengthening in said strong zone is accomplished by the application of additional pressure to enhance the bond at said capacitor element or at at least partly overlapping ones of said two coiled conductive tracks.

16. The security element as claimed in claim 15, wherein said strong zone is obtained by pressure forming said capacitor element or the at least partly overlapping ones of said two coiled conductive tracks into a three-dimensional shape.

17. The security element as claimed in claim 15, wherein the enhanced bonding and the forming of said capacitor element or said two coiled conductive tracks are accomplished in a single operation.

18. The security element as claimed in claim 1, wherein said selected area is characterized in that the dielectric layer has holes resulting from air inclusion.