SYSTEMS AND METHODS FOR COMPENSATION OF INTERFERENCE IN RADIOFREQUENCY IDENTIFICATION (RFID) DEVICES

• US 20170364718A1
• Filed: 06/17/2016
• Published: 12/21/2017
• Est. Priority Date: 06/17/2016
• Status: Active Grant

• Current Assignee: Intermec (Honeywell International Inc.)
• Original Assignee: Intermec (Honeywell International Inc.)
• Inventors: FINKE, Thomas
• Granted Patent: US 10,055,619 B2
• Time in Patent Office: Days
• CPC Class Codes: G06K 19/07749 the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card
• CPC Class Codes: G06K 19/07771 the record carrier comprising means for minimising adverse effects on the data communication capability of the record carrier, e.g. minimising Eddy currents induced in a proximate metal or otherwise electromagnetically interfering object
• CPC Class Codes: G06K 7/10158 methods and means used by the interrogation device for reliably powering the wireless record carriers using an electromagnetic interrogation field
• CPC Class Codes: G06K 7/10336 the antenna being of the near field type, inductive coil
• CPC Class Codes: H01Q 1/2208 associated with components used in interrogation type services, i.e. in systems for information exchange between an interrogator/reader and a tag/transponder, e.g. in Radio Frequency Identification [RFID] systems methods or arrangements for sensing record carriers, e.g. for reading patterns G06K7/00; record carrier for use with machines and with at least a part designed to carry digital markings G06K19/00
• CPC Class Codes: H01Q 7/00 Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop

Abstract

Systems and methods for compensating for interference in radiofrequency identification (RFID) devices are provided. One system includes an RFID antenna structure having a fixed antenna having a plurality of loops, one or more additional inductive loops and a switching arrangement coupled with the one or more additional inductive loops. The RFID antenna structure further includes a controller configured to control the switching arrangement to selectively switch the one or more additional inductive loops to change an inductance of the fixed antenna.

Claims

1. A radiofrequency identification (RFID) antenna structure comprising:

a fixed antenna having a plurality of loops;

one or more additional inductive loops that are not in direct electrical contact with the plurality of loops;

a switching arrangement coupled with the one or more additional inductive loops; and

a controller configured to control the switching arrangement to selectively switch the one or more additional inductive loops to change an inductance of the fixed antenna.

2. The RFID antenna of claim 1, wherein the one or more additional inductive loops comprise one or more loops positioned within the plurality of loops of the fixed antenna.

3. The RFID antenna of claim 1, further comprising a plurality of additional inductive loops, wherein the controller is configured to selectively and independently switch each of the loops of the plurality of additional inductive loops to activate or deactivate each of the loops.

4. The RFID antenna of claim 3, further comprising at least one switch coupled with each loop of the plurality of loops.

5. The RFID antenna of claim 1, wherein the switching arrangement comprises at least one metal-oxide-semiconductor (MOS) transistor.

6. The RFID antenna of claim 1, wherein the controller is configured for auto-tuning to change the inductance of the fixed antenna based on a surrounding conducted environment.

7. A radiofrequency identification (RFID) reader comprising:

a frequency generator configured to generate a carrier frequency signal;

an LC-matching circuit coupled to an output of the frequency generator;

an antenna coupled to an output of the LC-matching circuit and having one or more switchable inductive coils; and

a controller coupled with the antenna and configured to control the one or more switchable inductive coils of the antenna based on a surrounding conducted environment affecting an impedance of the antenna.

8. The RFID reader to claim 7, wherein the controller is configured to maintain a constant impedance of the antenna in different conducted environments.

9. The RFID reader to claim 8, wherein the controller is configured to maintain a constant card detection range in the different conducted environments.

10. The RFID reader to claim 8, wherein the controller is configured to maintain a constant impedance of 1 μ

H.

11. The RFID reader to claim 7, wherein the controller is configured to maintain a constant impedance of the antenna in different conducted environments including one or metal surfaces within six millimeters of the antenna.

12. The RFID reader to claim 7, wherein the antenna is a fixed loop coil antenna and the one or more switchable inductive coils comprise one or more inner antenna loop coils within loop coils of the fixed loop antenna.

13. The RFID reader to claim 12, further comprising a switching arrangement that includes one or more switching elements for resonantly coupling the one or more inner antenna loop coils to the fixed loop coil antenna to change the impedance of the fixed loop coil antenna.

14. The RFID reader to claim 13, further comprising at least two inner antenna loop coils.

15. The RFID reader to claim 7, wherein the antenna is configured to operate at a resonance frequency of between 9 MHz and 25 MHz.

16. The RFID reader to claim 7, wherein the controller is configured for auto-tuning operation to automatically change the inductance of the antenna based on the surrounding conducted environment affecting the impedance of the antenna.

17. A method for compensating for a conducted environment in radiofrequency identification (RFID), the method comprising selectively switching one or more inductive loops to resonantly couple, but not directly electrically contact, the one or more inductive loops with a fixed antenna of an RFID device to change the resonant operation of the antenna based on the conducted environment.

18. The method of claim 17, further comprising maintaining a substantially constant impedance of the fixed antenna in different conducted environments.

19. The method of claim 18, further comprising maintaining a constant impedance of about 1 μ

H.

20. The method of claim 17, further comprising maintaining the constant impedance of the antenna in different conducted environments including one or metal surfaces within six millimeters of the antenna.