System and Method for Selective Communication with RFID Transponders

• US 20050092838A1
• Filed: 11/19/2004
• Published: 05/05/2005
• Est. Priority Date: 03/11/2003
• Status: Abandoned Application

• Current Assignee: ZIH Corporation A Delaware Corporation With Its Principal Office In Hamilton Bermuda
• Original Assignee: ZIH Corp. (Zebra Technologies Corporation)
• Inventors: Tsirline, Boris Y., Gawelczyk, Robert, Hohberger, Clive P.
• Application Number:
  US10/904,635
• Publication Number:
  US 20050092838A1
• Time in Patent Office: Days
• US Class Current: 235/449
• CPC Class Codes: G06K 17/0025 the arrangement consisting of a wireless interrogation device in combination with a device for optically marking the record carrier
• 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 7/087 flux-sensitive, e.g. magnetic, detectors G06K7/10336 takes precedence

Abstract

A system having an RFID transceiver is adapted to communicate exclusively with a single RFID transponder located in a predetermined confined transponder target area. The system includes a magnetic coupling device comprising a magnetic flux generator responsive to a radio frequency input signal and a magnetic field pattern former. The pattern former is configured to collect flux produced by the flux generator and to form a field pattern in the location of the transponder target area. The system establishes, at predetermined transceiver power levels, a mutual magnetic coupling which is selective exclusively for a single transponder located in the transponder target area.

Claims

1. A method of establishing communication between a transceiver and a single RFID transponder located in a predetermined confined transponder target area, comprising:

generating a magnetic flux field which varies in response to a radio frequency input signal; and

collecting and forming said magnetic field pattern in the location of said transponder target area; and

establishing at predetermined power levels of the transceiver a mutual magnetic coupling which is selective exclusively for a single transponder located in said transponder target area.

2. The method defined by claim 1 including locating in said magnetic flux field a ferrite structure having a gap, said field pattern being formed within and adjacent to said gap.

3. The method defined by claim 1 including transporting a web of labels through said target area, at least some of which labels have an RFID transponder, and wherein said method includes printing on said labels.

4. The method defined by claim 1 including suppressing electric fields associated with said generating of said magnetic flux field, which fields would otherwise reach said target area.

5. A magnetic coupling device, comprising:

a coil having a first side and a second side;

a magnetic field pattern former; and

the magnetic field pattern former covering the first side of the coil and at least a portion of the second side of the coil.

6. The magnetic coupling device of claim 5, wherein the coil is formed as at least a first trace on a printed circuit board.

7. The magnetic coupling device of claim 5, wherein the magnetic field pattern former has a magnetic permeability of at least 20.

8. The magnetic coupling device of claim 5, wherein the magnetic field pattern former is ferrite.

9. The magnetic coupling device of claim 8, wherein the ferrite is flexible and the ferrite is applied to cover the first side of the coil, around at least a first edge and at least a portion of a second side of the coil.

10. The magnetic coupling device of claim 9, wherein the portion of the second side of the coil that is covered by the ferrite is at least 30 percent.

11. The magnetic coupling device of claim 5, further including a first RF shield covering a first side of the coil.

12. The magnetic coupling device of claim 11, wherein the first RF shield has a loop shape with an open circuit.

13. The magnetic coupling device of claim 11, wherein the first RF shield is coupled to an electrical ground.

14. The magnetic coupling device of claim 11, further including a second RF shield covering a second side of the coil.

15. The magnetic coupling device of claim 6, further including a first RF shield covering the first trace;

the first RF shield formed as a second trace on the printed circuit board.

16. The magnetic coupling device of claim 5, further including:

at least one capacitor in one of series with the coil for series resonance and across the coil for parallel resonance.

17. A planar coil printed circuit board magnetic coupling device, comprising:

a first trace on the printed circuit board forming the planar coil;

a first RF shield, the first RF shield insulated from and covering a first side of the first trace;

a second RF shield, the second RF shield insulated from and covering a second side of the first trace; and

a magnetic field pattern former covering a first side of the printed circuit board area covered by the first trace and at least a portion of a second side of the printed circuit board area covered by the first trace.

18. The magnetic coupling device of claim 17, wherein:

the first RF shield is a second trace on the printed circuit board.

19. The magnetic coupling device of claim 17, wherein:

the first RF shield has an open circuit.

20. The magnetic coupling device of claim 17, wherein:

the magnetic field pattern former has a magnetic permeability of at least 20.

21. The magnetic coupling device of claim 20, wherein:

the magnetic field pattern former is flexible ferrite.

22. A method for increasing planar selectivity of a magnetic coupling device, comprising the steps of:

covering an area of the magnetic coupling device where a magnetic field emanation is not desired with a magnetic field pattern former.

23. The method of claim 22, wherein the magnetic field pattern former has a magnetic permeability of at least 20.

24. The method of claim 22, wherein the magnetic field pattern former is flexible ferrite.

25. The method of claim 24, wherein the flexible ferrite is arranged to cover a first side of the magnetic coupling device, a first edge of the magnetic coupling device and at least a portion of a second side of the magnetic coupling device.

26. A transponder communication selective module, comprising:

a magnetic coupling device partially covered by a magnetic field pattern former;

located proximate a media feed path;

the media feed path arranged to carry a plurality of transponders sequentially past the magnetic coupling device.

27. The apparatus of claim 26, further including a printhead arranged to apply indicia upon an outer surface of the transponders.

28. The apparatus of claim 26, wherein the outer surface is a label.

29. The apparatus of claim 26 wherein, the magnetic coupling device is formed as at least a first trace on a printed circuit board.

30. The apparatus of claim 26, wherein the magnetic field pattern former has a magnetic permeability of at least 20.

31. The apparatus of claim 26, wherein the magnetic field pattern former is ferrite.

32. The apparatus of claim 31, wherein the ferrite is flexible and the ferrite is applied to cover the first side of the magnetic coupling device, around at least a first edge and at least a portion of a second side of the magnetic coupling device.

33. The apparatus of claim 32, wherein the portion of the second side of the magnetic coupling device that is covered by the ferrite is at least 30 percent.

34. The apparatus of claim 26, further including a first RF shield covering a first side of the magnetic coupling device.

35. The apparatus of claim 34, wherein the first RF shield has a loop shape with an open circuit.

36. A system for sequentially communicating with a plurality of RFID transponders, comprising:

a magnetic coupling device located proximate a media supply path arranged to transport RFID transponders sequentially past the magnetic coupling device;

the magnetic coupling device having a magnetic field pattern former arranged to minimize magnetic flux emanation away from the magnetic coupling device, except through a gap; and

the gap dimensioned to enable inductive coupling with only a single RFID transponder at a time.

37. A method for selectively communicating with a desired RFID transponder among a plurality of RFID transponders, comprising the steps of:

energizing a magnetic coupling device; and

passing the desired RFID transponder through a magnetic flux field generated by the magnetic coupling device;

the magnetic coupling device covered on a first side and at least a portion of a second side by a magnetic field pattern former whereby a magnetic flux field generated by the magnetic coupling device is in an area small enough so that only the desired RFID transponder is energized.

38. The method of claim 37, wherein the magnetic field pattern former is formed from a flexible ferrite material.