Dual mode EAS/RFID tag based on self tuning RFID chip

Patent metadata

Field	Value
Publication number	US-11630979-B2
Application number	US-202017102100-A
Country	US
Kind code	B2
Filing date	Nov 23, 2020
Priority date	Nov 26, 2019
Publication date	Apr 18, 2023
Grant date	Apr 18, 2023

Abstract

A self-tuning RFID device having an input capacitance that is adjustable in response to a detected signal. The self-tuning RFID device preferably comprises a variable capacitance RFID chip coupled to an inductor, and an input circuit driven by the detected signal from the variable capacitance RFID chip. A change in capacitance with the detected signal is delayed by a specific amount of time, thereby allowing the self-tuning RFID device to function as a dual mode EAS and RFID tag. The ESA functionality can be deactivated by a high field at or near its resonance frequency without disabling the RFID functionality. The effect of the high field may change the input capacitance permanently changing its resonance.

First claim

What is claimed is:

1. A self-tuning RFID device comprising:
a variable capacitance RFID chip that adjusts in response to a level of a detected voltage;
an inductor operatively coupled to the variable capacitance RFID chip; and
an input circuit powered by the detected voltage, wherein when the detected voltage from an illuminating field is above a resonance frequency, a reduction in capacitance of the variable capacitance RFID chip in response to the detected voltage locks the self-tuning RFID device on the illuminating field, and wherein the reduction in the capacitance with the detected voltage is delayed for a period of time.

2. The self-tuning RFID device of claim 1 , wherein the capacitance of the input circuit is inversely proportional to the detected voltage.

3. The self-tuning RFID device of claim 1 , wherein the detected voltage reduces the capacitance of the input circuit.

4. The self-tuning RFID device of claim 1 , wherein the self-tuning RFID device has an EAS functionality and a RFID functionality.

5. The self-tuning RFID device of claim 4 , wherein the RFID device functionality is preserved and the EAS functionality is disabled.

6. The self-tuning RFID device of claim 1 , wherein a capacitance is permanently changed from a value resonating the inductor at 8.2 M HZ to a second value resonating the inductor at 13.56 M Hz.

7. The self-tuning RFID device of claim 1 , wherein a resistive load that the variable capacitance RFID chip presents to the inductor is variable.

8. The self-tuning RFID device of claim 1 , wherein a delay is provided between the detected voltage and a voltage driving the input circuit.

9. The self-tuning RFID device of claim 8 , wherein the delay allows the variable capacitance RFID chip to deactivate an EAS functionality while preserving a RFID functionality.

10. The self-tuning RFID device of claim 1 further comprising a processing unit for adjusting a capacitance of the variable capacitance RFID chip.

11. The self-tuning RFID device of claim 1 , wherein the self-tuning RFID device operates in at least one of: an EAS functionality mode; a deactivated state mode; and a RFID functionality mode.

12. The self-tuning RFID device of claim 1 , wherein, when the self-tuning RFID device is initially tuned to a frequency of 8.2 MHz, the detected voltage causes a reduction in capacitance that retunes the self-tuning RFID device to a frequency of 13.56 MHz.

13. An RFID device having an EAS functionality and a RFID functionality comprising:
a RFID logic circuit;
an inductor operatively coupled to the RFID logic circuit;
a first input capacitance operatively coupled to the RFID logic circuit; and
a second input capacitance operatively coupled to the RFID logic circuit, wherein the RFID logic circuit is powered by a detected voltage, and wherein when the detected voltage from an illuminating field is above a resonance frequency it causes locking of the RFID device on the illuminating field, and wherein further the second input capacitance is disconnected, disabling the EAS functionality of the RFID logic circuit.

14. The RFID device of claim 13 , wherein the RFID device operates with the EAS functionality at a resonance frequency of 8.2 MHz.

15. The RFID device of claim 13 , wherein a resonance frequency of 13.56 MHz disables the EAS functionality while maintaining the RFID functionality.

16. An RFID device having an EAS functionality and a RFID functionality comprising:
a RFID logic circuit;
an inductor;
a first input capacitance;
a second input capacitance; and
a timing circuit operatively coupled to the RFID logic circuit, wherein the RFID logic circuit is powered by a detected voltage, and wherein when the detected voltage from an illuminating field is above a resonance frequency it causes locking of the RFID device on the illuminating field, and wherein further the second input capacitance is disconnected, disabling the EAS functionality of the RFID logic circuit.

17. The RFID device of claim 16 further comprising a power recovery detector operatively coupled to the RFID logic circuit.

18. The RFID device of claim 16 , wherein a parallel input resistance of the RFID logic circuit associated with a power drain dependent on a frequency is alterable.

Assignees

• Forster Ian J
• Avery Dennison Retail Information Services Llc

Inventors

• Forster Ian J

Classifications

• G06K19/0726 Primary

  the arrangement including a circuit for tuning the resonance frequency of an antenna on the record carrier · CPC title

• G08B13/2417

  having a radio frequency identification chip · CPC title

• G08B13/2448

  Tag with at least dual detection means, e.g. combined inductive and ferromagnetic tags, dual frequencies within a single technology, tampering detection or signalling means on the tag · CPC title

• G08B13/242

  Tag deactivation · CPC title

• G08B13/2431 Primary

  Tag circuit details · CPC title