EAS tag with helical coil

• US 4,774,504 A
• Filed: 06/22/1987
• Issued: 09/27/1988
• Est. Priority Date: 06/22/1987
• Status: Expired due to Term

• Current Assignee: Sensormatic Electronics Corporation (Johnson Controls International plc)
• Original Assignee: Monarch Marking Systems, Inc. (Avery Dennison Corporation)
• Inventors: Hartings, Michael F.
• Primary Examiner(s): Swann, III, Glen R.
• Application Number:
  US07/064,712
• Time in Patent Office: 463 Days
• Field of Search: 340/572, 343/866, 343/894, 343/895
• US Class Current: 340/572.5
• CPC Class Codes: E05B 73/0017 Anti-theft devices, e.g. tags or monitors, fixed to articles, e.g. clothes, and to be removed at the check-out of shops
• CPC Class Codes: E05B 73/0052 of the magnetic type

Abstract

An anti-theft tag for use in an electronic article surveillance system has a housing, a lock for releasably attaching the housing to an article to be protected, and a marker on the housing, the marker having a resonant circuit including an inductor and a capacitor, the inductor including a solenoid type winding defining a winding opening, wherein the circuit has a Performance Factor P of at least 1×10⁶ in the equation P=QA¹.5, wherein Q is equal to the circuit Q, and wherein A is equal to the area of the winding opening in square millimeters.

Claims

1. A tag for use in an electronic article surveillance system, the tag comprising:

a housing, a detectable marker held by the housing, means for attaching the housing to an article to be protected, wherein the marker includes a resonant circuit including an inductor and a capacitor, wherein the inductor is comprised of a solenoid type winding defining a winding opening, wherein the circuit has a Performance Factor P of at least 1×

10⁶ in the equation P=QA¹.5, wherein Q is equal to the circuit Q, and wherein A is equal to the area of the winding opening in square millimeters.

2. A tag as defined in claim 1, wherein the winding opening is generally square.

3. A tag as defined in claim 1, wherein the area A is at least 980 sq. millimeters.

4. A tag as defined in claim 1, wherein the attaching means includes a metal component and is disposed outside the winding opening.

5. A tag as defined in claim 4, wherein the winding has no more than two turns.

6. A tag as defined in claim 4, wherein the winding has no more than three turns.

7. A tag as defined in claim 1, wherein the winding is comprised of one piece of wire having a diameter of at least 0.16 millimeter.

8. A tag as defined in claim 1, wherein the winding is comprised of one piece of wire having a diameter of between 0.16 and 2.05 millimeters.

9. A tag as defined in claim 1, wherein the winding has no more than two turns.

10. A tag as defined in claim 1, wherein the winding has no more than three turns.

11. A tag as defined in claim 1, wherein the winding has no more than ten turns.

12. A tag for use in an electronic article surveillance system, the tag comprising:

a housing, a detectable marker held by the housing, means for attaching the housing to an article to be protected, wherein the marker includes a resonant circuit including an inductor and a capacitor, wherein the inductor is comprised of a solenoid-type winding defining a winding opening, the winding having spaced terminal end portions extending into the opening, and the capacitor being electrically connected to the terminal end portions.

13. A tag as defined in claim 12, wherein the winding comprises no more than three turns.

14. A tag as defined in claim 12, wherein the winding comprises essentially two complete turns.

15. A tag as defined in claim 12, wherein the winding is comprised of wire having a diameter of between 0.16 and 2.05 millimeters.

16. A tag as defined in claim 12, wherein the opening has an area of between 980 and 7500 square millimeters.

17. A tag as defined in claim 12, wherein the opening has an area of at least 980 square millimeters.

18. A tag as defined in claim 12, wherein the opening has an area of between 980 and 2000 square millimeters.

19. A tag as defined in claim 12, wherein the circuit has a Q of at least 25.