Electronic article surveillance and identification device, system, and method

• US 6,356,197 B1
• Filed: 04/03/2000
• Issued: 03/12/2002
• Est. Priority Date: 04/03/2000
• Status: Expired due to Term

• Current Assignee: Sensormatic Electronics LLC (Johnson Controls International plc)
• Original Assignee: Sensormatic Electronics Corporation (Johnson Controls International plc)
• Inventors: Lian, Ming-Ren, Patterson, Hubert A.
• Primary Examiner(s): TWEEL JR, JOHN ALEXANDER
• Application Number:
  US09/541,419
• Time in Patent Office: 708 Days
• Field of Search: 340/572.1, 340/572.4, 340/572.5, 340/551, 340/562, 340/825.44, 340/572.3
• US Class Current: 340/572.1
• CPC Class Codes: G06K 19/0723 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 Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer

Abstract

An electronic article surveillance and identification tag and system is provided. The tag couples energy from a radiated energy source, which comprises first and second radiated signals. A mixing member in the tag mixes the first and second signals to produce a sideband of the first signal, which is re-radiated by the tag. The mixing member is activated by a controller that switches the mixing member into and out of the circuit according to a code stored within the controller that is associated with an article to be identified. As the mixing member is activated and deactivated, the sideband is radiated in a sequential manner according to the stored code. A receiver detects the sideband, and a decoder recovers the stored code according to the sequence of received sideband emissions from the tag.

Claims

1. An electronic article surveillance and identification tag, comprising:

energy coupling means for receiving transmitted energy and re-radiating said energy, said transmitted energy comprising a first signal at a first frequency and a second signal at a second frequency;

means for mixing said first and said second signals together forming a sideband signal for re-radiating by said energy coupling means; and

a controller for switching on and off said means for mixing according to a pre-selected stored data code associated with an article to be identified.

2. The tag as recited in claim 1, wherein said energy coupling means comprises an inductor and a capacitor.

3. The tag as recited in claim 2, wherein said means for mixing comprises a magnetic member connected to said inductor and said capacitor.

4. The tag as recited in claim 3, wherein said second signal is a magnetic field and said magnetic member exhibits a magneto-impedance effect by changing impedance when said magnetic field is applied to said magnetic member.

5. The tag as recited in claim 4, wherein said first frequency is about 13.56 MHz, and said second frequency is lower that said first frequency.

6. The tag as recited in claim 4, wherein said first frequency is about 25.50 MHz, and said second frequency is lower that said first frequency.

7. The tag as recited in claim 1 further comprising means for deactivating said controller when said energy coupling means receives said transmitted energy below a pre-selected minimum level, said means for mixing being on when said controller is deactivated wherein said sideband signal is continuously formed and re-radiated.

8. The tag as recited in claim 7 wherein said controller comprises a power rectifier connected to said energy coupling means, a logic control unit connected to said power rectifier, a switching unit connected to said means for mixing and to said logic control unit, and a programmable nonvolatile memory module connected to said logic control unit, said memory module comprising storage of said pre-selected stored data code, said code being changeable.

9. The tag as recited in claim 1, wherein said energy coupling means comprises a dipole antenna.

10. The tag as recited in claim 9, wherein said means for mixing comprises a diode connected to said dipole antenna, said controller connected to said diode for momentarily and sequentially shorting said diode according to said pre-selected stored data code.

11. The tag as recited in claim 10 further comprising means for deactivating said controller when said transmitted energy received from said dipole antenna falls below a pre-selected minimum level, said means for mixing being switched on when said controller is deactivated to continue re-radiating said sideband from said energy coupling means.

12. The tag as recited in claim 11 wherein said controller comprises a power rectifier connected to said dipole antenna, a logic control unit connected to said power rectifier, a switching unit connected to said diode and to said logic control unit, and a programmable nonvolatile memory module connected to said logic control unit, said memory module comprising storage of said pre-selected data code, said code being changeable.

13. The tag as recited in claim 12, wherein said first frequency is in the frequency range of about 900 MHz to about 3 GHz and said second frequency is lower that said first frequency.

14. An electronic article surveillance and identification tag, comprising:

a substrate;

an inductor formed on said substrate;

a capacitor formed on said substrate and connected to said inductor, said inductor and said capacitor defining a resonant circuit;

a magnetic member connected to said inductor and said capacitor; and

,

a controller connected to said magnetic member for momentarily and sequentially shorting said magnetic member according to a pre-selected stored data code associated with an article to be identified.

15. The tag as recited in claim 14, wherein said magnetic member exhibits a magneto-impedance effect by changing impedance when a magnetic field is applied to said magnetic member.

16. The tag as recited in claim 15 further comprising means for deactivating said controller when power received from said inductor and said capacitor falls below a pre-selected minimum level, said magnetic member being non-shorted when said controller is deactivated.

17. The tag as recited in claim 16 wherein said controller comprises a power rectifier connected to said inductor and said capacitor, a logic control unit connected to said power rectifier, a switching unit connected to said magnetic member and to said logic control unit, and a programmable nonvolatile memory module connected to said logic control unit, said memory module comprising storage of said pre-selected data code, said code being changeable.

18. An electronic article surveillance and identification system, comprising:

interrogation means for generating a first signal at a first frequency and a second signal at a second frequency, said second signal being a magnetic field at a second frequency lower than said first frequency;

a tag having energy coupling means for receiving said first and said second signals, means for mixing said first and said second signals together and generating a sideband of said first frequency for re-radiating by said energy coupling means, said means for mixing comprising a magnetic member exhibiting a magneto-impedance effect from said second signal, and a controller for switching on and off said means for mixing according to a pre-selected stored data code associated with an article to be identified;

detection means for detecting said sideband; and

decoding means for decoding said pre-selected stored data code from said sideband.

19. The system as recited in claim 18 further comprising means to change said pre-selected stored data code.

20. A method of operating an electronic article surveillance and identification system, comprising the steps of:

providing a tag comprising a tuned circuit and a signal mixing member;

transmitting a first signal at a resonant frequency of said tuned circuit;

transmitting a second signal at a frequency that is lower than said first signal, said second signal activating said signal mixing member;

sequentially turning on and off said signal mixing member according to a pre-selected data code associated with an article to be identified;

detecting a sideband of said first signal, said sideband generated by said signal mixing member mixing said first and said second signals; and

decoding said pre-selected data code from said detected sideband.

21. The method of claim 20 wherein the step of providing said tag comprises providing a tuned LC circuit and a magnetic signal mixing member exhibiting a magneto-impedance effect when exposed to a magnetic field;

and,

transmitting said first signal at a resonant frequency of said LC circuit;

transmitting said second signal at a frequency that is lower than said first signal, said second signal comprising said magnetic field;

sequentially turning on and off said magnetic signal mixing member according to said pre-selected data code associated with an article to be identified;

detecting a sideband of said first signal, said sideband generated by said magnetic signal mixing member mixing said first and said second signals; and

decoding said pre-selected data code from said detected sideband.

22. The method of claim 20 wherein the step of providing said tag comprises providing a tuned dipole antenna and a diode signal mixing member activated by exposure to an electric field;

and,

transmitting said first signal at a resonant frequency of said tuned dipole antenna;

transmitting said second signal at a frequency that is lower than said first signal, said second signal comprising said electric field;

momentarily and sequentially disabling said diode signal mixing member according to said pre-selected data code associated with an article to be identified;

detecting a sideband of said first signal, said sideband generated by said diode signal mixing member mixing said first and said second signals; and