Self-detaching anti-theft device with energy limit

Patent metadata

Field	Value
Publication number	US-11205106-B2
Application number	US-202016784666-A
Country	US
Kind code	B2
Filing date	Feb 7, 2020
Priority date	Sep 19, 2019
Publication date	Dec 21, 2021
Grant date	Dec 21, 2021

Abstract

Systems and methods for operating a security tag. The methods comprise: receiving a first wireless signal using a receive circuit of the security tag; inducing a voltage in the receive circuit of the security tag while the first wireless signal is being received; performing operations by a controller to selectively close a switch while the voltage is being induced in the circuit; causing a release of a mechanical component of the security tag by allowing energy to flow from the receive circuit to the mechanical component when the switch is closed; and performing operations by the controller to prevent damage to the mechanical component as a result of the security tag being a certain distance from an external device.

First claim

We claim:

1. A method for operating a security tag, comprising:
receiving a first wireless signal transmitted from an external transmit circuit using a receive circuit of the security tag;
inducing a voltage in the receive circuit of the security tag while the first wireless signal is being received;
performing operations by a controller of the security tag to selectively close a switch;
causing a release of a mechanical component of the security tag by allowing energy to flow from the receive circuit to the mechanical component when the switch is closed;
monitoring a level of energy dissipation by the mechanical component;
determining when an accumulated amount of energy dissipation by the mechanical component exceeds a threshold value; and
interrupting the flow of energy from the from the receive circuit to the mechanical component when the accumulated amount of energy dissipation by the mechanical component exceeds the threshold value.

2. The method according to claim 1 , wherein the flow of energy is interrupted by opening the switch.

3. The method according to claim 1 , wherein the threshold value represents an upper safe operational limit of the mechanical component.

4. The method according to claim 1 , further comprising selectively opening the switch upon expiration of a pre-defined period of time starting from a time at which the switch was closed.

5. The method according to claim 1 , further comprising selectively opening the switch when motion of the mechanical component is detected by the controller.

6. The method according to claim 1 , wherein the release of the mechanical component is achieved by transitioning a pin from an engaged position to an unengaged position without any human assistance or mechanical assistance by a device external to the security tag.

7. The method according to claim 1 , wherein the voltage is induced in the receive circuit via resonant inductive coupling between the external transmit circuit and the inductor of the receive circuit.

8. The method according to claim 1 , wherein an inductor in the receive circuit resonates with a capacitor when the switch is closed.

9. The method according to claim 8 , wherein the capacitor is tuned to a frequency that is the same as a frequency to which the external transmit circuit is tuned.

10. The method according to claim 1 , wherein the mechanical component of the security tag is connected directly between the switch and a capacitor of the receive circuit.

11. The method according to claim 1 , further comprising harvesting energy by the security tag when the switch is open.

12. The method according to claim 11 , further comprising discontinuing energy harvesting by the security tag when the switch is closed.

13. A security tag, comprising:
a switch;
a receive circuit configured to receive a wireless signal transmitted from an external transmit circuit;
a controller coupled to the switch and the receive circuit; and
a mechanical component that is coupled to the switch and facilitates attachment of the security tag to an article;
wherein a voltage is induced in the receive circuit when the wireless signal is being received;
wherein the mechanical component is released by allowing energy to flow from the receive circuit to the mechanical component when the switch is closed; and
wherein the controller:
monitors a level of energy dissipation by the mechanical component;
determines when an accumulated amount of energy dissipation by the mechanical component exceeds a threshold value; and
interrupts the flow of energy from the from the receive circuit to the mechanical component when the accumulated amount of energy dissipation by the mechanical component exceeds the threshold value.

14. The security tag according to claim 13 , wherein the flow of energy is interrupted by opening the switch.

15. The security tag according to claim 13 , wherein the threshold value represents an upper safe operational limit of the mechanical component.

16. The security tag according to claim 13 , wherein the switch is selectively opened upon expiration of a pre-defined period of time starting from a time at which the switch was closed.

17. The security tag according to claim 13 , wherein the switch is selectively opened when motion of the mechanical component is detected.

18. The security tag according to claim 13 , wherein the release of the mechanical component is achieved by transitioning a pin from an engaged position to an unengaged position without any human assistance or mechanical assistance by a device external to the security tag.

19. The security tag according to claim 13 , wherein the voltage is induced in the receive circuit via resonant inductive coupling between the external transmit circuit and the inductor of the receive circuit.

20. The security tag according to claim 13 , wherein an inductor in the receive circuit resonates with a capacitor when the switch is closed.

21. The security tag according to claim 20 , wherein the capacitor is tuned to a frequency that is the same as a frequency to which the external transmit circuit is tuned.

22. The security tag according to claim 13 , wherein the mechanical component of the security tag is connected directly between the switch and a capacitor of the receive circuit.

23. The security tag according to claim 13 , wherein the security tag harvests energy when the switch is open.

24. The security tag according to claim 23 , wherein energy harvesting by the security tag is discontinued with the switch is closed.

Assignees

• Easter Ronald B
• Soto Manuel
• Mohiuddin Mohammad
• Sensormatic Electronics Llc

Inventors

• Easter Ronald B
• Soto Manuel
• Mohiuddin Mohammad

Classifications

• G06K19/0723 Primary

  the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs · CPC title

• H04B5/02

  Electricity · mapped topic

• H04B5/48 Primary

  Transceivers · CPC title