Self-parameterising RFID antenna extender

• US 8,840,023 B2
• Filed: 11/10/2010
• Issued: 09/23/2014
• Est. Priority Date: 12/01/2009
• Status: Active Grant

• Current Assignee: Schneider Electric Industries SAS (Schneider Electric SE)
• Original Assignee: Schneider Electric Industries SAS (Schneider Electric SE)
• Inventors: Chauvet, Francis
• Primary Examiner(s): St Cyr, Daniel
• Application Number:
  US13/509,123
• Publication Number:
  US 20120248186A1
• Time in Patent Office: 1,413 Days
• Field of Search: 235/439, 235/492
• US Class Current: 235/439
• 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 19/0726 the arrangement including a circuit for tuning the resonance frequency of an antenna on the record carrier
• CPC Class Codes: G06K 19/07767 the first and second communication means being two different antennas types, e.g. dipole and coil type, or two antennas of the same kind but operating at different frequencies
• 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
• CPC Class Codes: G06K 7/10178 including auxiliary means for focusing, repeating or boosting the electromagnetic interrogation field comparable booster antennas integrated on the record carrier itself G06K19/07794

Abstract

An antenna extender configured to be coupled electromagnetically to an RFID read/write station. The extender includes a first circuit oscillating at variable frequency and a second oscillating circuit coupled to the first oscillating circuit, and a processing unit which is powered by energy supplied by the second oscillating circuit when the extender is placed close to the read/write station. The processing unit includes a mechanism to measure voltage at terminals of the second oscillating circuit and a controller that can be used to vary resonance frequency of the first oscillating circuit as a function of the value of the measured voltage to optimize frequency tuning between the extender and the read/write station.

Claims

1. An antenna extender configured to be coupled electromagnetically to an RFID read/write station, the antenna extender comprising:

a first oscillating circuitry and a second oscillating circuitry coupled to the first oscillating circuitry; and

a processing circuitry which is powered by energy provided by the second oscillating circuitry when the antenna extender is placed near the RFID read/write station,

wherein the processing circuitry includes;

a measurement circuitry configured to measure a voltage across terminals of the second oscillating circuitry, and

a control circuitry configured to vary a resonance frequency of the first oscillating circuitry as a function of a value of the measured voltage, so as to optimize frequency tuning between the antenna extender and the RFID read/write station.

2. The antenna extender as claimed in claim 1, wherein the control circuitry varies the resonance frequency of the first oscillating circuitry so as to obtain a maximum value of the measured voltage.

3. The antenna extender as claimed in claim 1, wherein the measurement circuitry measures a peak voltage at the terminals of the second oscillating circuitry.

4. The antenna extender as claimed in claim 3, wherein varying the resonance frequency of the first oscillating circuitry automatically varies a value of the peak voltage of the second oscillating circuitry.

5. The antenna extender as claimed in claim 3, wherein the measurement circuitry comprises a diode and a capacitor connected in parallel to measure the peak voltage at the terminals of the second oscillating circuitry.

6. The antenna extender as claimed in claim 1, wherein the measurement circuitry measures an effective voltage or a mean voltage at the terminals of the second oscillating circuitry.

7. The antenna extender as claimed in claim 1, wherein the first oscillating circuitry includes a variable capacitor, and the control circuitry varies a value of the variable capacitor.

8. The antenna extender as claimed in claim 1, wherein the variable capacitor includes one or more variable-capacitance diodes.

9. The antenna extender as claimed in claim 7, wherein the variable capacitor includes a plurality of capacitors linked in parallel and switchable with aid of bistable switches controlled by the control circuitry.

10. The antenna extender as claimed in claim 7, wherein the first oscillating circuitry further includes a fixed additional capacitor linked in parallel with the variable capacitor.

11. The antenna extender as claimed in claim 7, wherein the control circuitry varies the resonance frequency of the first oscillating circuitry by varying the value of the variable capacitor.

12. The antenna extender as claimed in claim 7, wherein the processing circuitry further includes a backup memory circuitry configured to store the value of the variable capacitor when a power supply is cut off.

13. The antenna extender as claimed in claim 1, wherein the first oscillating circuitry includes a variable coil, and the control circuitry varies a value of the variable coil.

14. The antenna extender as claimed in claim 1, wherein a first resonance frequency of the second oscillating circuitry is different from a second resonance frequency of an antenna of the RFID read/write station.

15. The antenna extender as claimed in claim 1, wherein the first oscillating circuitry and the second oscillating circuitry are electromagnetically coupled.

16. A system for exchanging data, comprising:

an RFID read/write station;

at least one RFID tag; and

an antenna extender configured to be coupled electromagnetically to the RFID read/write station to allow the RFID read/write station to be able to communicate with the at least one RFID tag by electromagnetic coupling, the antenna extender including;

a first oscillating circuitry and a second oscillating circuitry coupled to the first oscillating circuitry; and

a processing circuitry which is powered by energy provided by the second oscillating circuitry when the antenna extender is placed near the RFID read/write station,

wherein the processing circuitry includes;

a measurement circuitry configured to measure a voltage across terminals of the second oscillating circuitry, and

a control circuitry configured to vary a resonance frequency of the first oscillating circuitry as a function of a value of the measured voltage, so as to optimize frequency tuning between the antenna extender and the RFID read/write station.

17. A method for optimizing frequency tuning of an antenna extender coupled electromagnetically with an RFID read/write station, the antenna extender comprising a processing circuitry, a first oscillating circuitry, and a second oscillating circuitry, the method comprising:

measuring, using the processing circuitry, a voltage across terminals of the second oscillating circuitry; and

varying, using the processing circuitry, a resonance frequency of the first oscillating circuitry as a function of a value of the measured voltage, so as to obtain a maximum value of the measured voltage.

18. The method of optimization as claimed in claim 17, wherein the method is executed each time the processing circuitry is powered up.

19. The method of optimization as claimed in claim 17, wherein the method is executed periodically by the processing circuitry.