System and Method for Selective Communication with RFID Transponders

• US 20040178267A1
• Filed: 03/11/2003
• Published: 09/16/2004
• Est. Priority Date: 03/11/2003
• Status: Active Grant

• Current Assignee: Zebra Technologies Corporation
• Original Assignee: Zebra Technologies Corporation
• Inventors: Tsirline, Boris Y., Gawelczyk, Robert, Hohberger, Clive P.
• Granted Patent: US 6,848,616 B2
• 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 printer including a transceiver adapted to communicate with RFID transponders, comprising:

a printhead;

a media conveyance adapted to transport a series of discrete media to said printhead and through a transponder target area, at least some of said media including an RFID transponder;

a magnetic flux generator responsive to a radio frequency input signal; and

a magnetic field pattern former configured to collect flux produced by said magnetic coupling device and to form a field pattern in the location of said transponder target area, said transceiver being configured to establish at predetermined power levels a mutual magnetic coupling which is selective exclusively for a single transponder located in said transponder target area.

2. The printer defined by claim 1 wherein said magnetic flux generator comprises a coil receiving said input signal.

3. The printer defined by claim 2 wherein said magnetic field pattern former comprises a ferrite structure arranged to partially surround said coil and having a gap within and adjacent to which said field pattern is formed.

4. The printer defined by claim 1 wherein said magnetic field pattern former comprises a ferrite structure.

5. The printer defined by claim 1 wherein said printhead is positioned and configured to print on or adjacent said transponder while it is still in said target area.

6. The printer defined by claim 1 wherein said printhead is positioned and configured to print on or adjacent said transponder when it is outside of said target area.

7. The printer defined by claim 1 adapted to feed a web of spaced transponders through said target area, and wherein said printer communicates with a transponder located in said target area but concurrently not with another transponder located outside of said target area.

8. The printer defined by claim 1 wherein said magnetic field pattern former comprises a ferrite structure arranged to partially surround said flux generator and having a gap within and adjacent to which said field pattern is formed.

9. The printer defined by claim 8 wherein said gap is located at an end of said pattern former adjacent the printhead, and wherein said printhead is positioned and configured to print on or adjacent said transponder while it is in said target area.

10. The printer defined by claim 8 wherein said gap is located intermediate opposed ends of said pattern former, and wherein said printhead is positioned and configured to print on or adjacent said transponder when it is outside of said target area.

11. The printer defined by claim 1 including an electric field suppressor located between said magnetic flux generator and said target area.

12. The printer defined by claim 11 wherein said magnetic flux generator comprises a coil, and wherein said suppressor comprises a metal shield adapted to suppress eddy currents.

13. The printer defined by claim 1 wherein said magnetic field pattern former has a relative permeability greater than 20.

15. The system defined by claim 1 wherein said flux generator comprises a coil receiving said input signal.

16. The system defined by claim 15 wherein said magnetic field pattern former comprises a ferrite structure arranged to partially surround said coil and having a gap within and adjacent to which said field pattern is formed.

14. A system comprising an RFID transceiver and adapted to communicate exclusively with a single RFID transponder located in a predetermined confined transponder target area, said system comprising:

a magnetic flux generator responsive to a radio frequency input signal; and

a magnetic field pattern former configured to collect flux produced by said flux generator and to form a field pattern in the location of said transponder target area, said system being configured to establish at predetermined transceiver power levels a mutual magnetic coupling which is selective exclusively for a single transponder located in said transponder target area.

17. The system defined by claim 14 wherein said magnetic field pattern former comprises a ferrite structure.

18. The system defined by claim 14 wherein said system comprises a printer and includes a printhead.

19. The system defined by claim 18 wherein said printhead is positioned and configured to print on or adjacent said transponder while it is still in said target area.

20. The system defined by claim 18 wherein said printhead is positioned and configured to print on or adjacent said transponder when it is outside of said target area.

21. The system defined by claim 14 adapted to feed a web of spaced transponders through said target area, and wherein said system communicates with a transponder located in said target area but concurrently not with another transponder located outside of said target area.

22. The system defined by claim 21 wherein said target area is not significantly greater than a periodicity “

P”

.

23. The system defined by claim 14 wherein said target area is not significantly greater than the width of an individual transponder.

24. The system defined by claim 14 which includes a printhead and wherein said magnetic field pattern former comprises a ferrite structure arranged to partially surround said flux generator and having a gap within and adjacent to which said field pattern is formed.

25. The system defined by claim 24 wherein said gap is located at an end of said pattern former adjacent the printhead, and wherein said printhead is positioned and configured to print on or adjacent said transponder while it is in said target area.

26. The system defined by claim 24 wherein said gap is located intermediate opposed ends of said pattern former, and wherein said printhead is positioned and configured to print on or adjacent said transponder when it is outside of said target area.

27. The system defined by claim 14 including a media conveyance configured to transport a web of labels of periodicity “

P”

through said target area, at least some of which labels have an RFID transponder, wherein said system includes a printhead for printing on said labels, wherein said magnetic flux generator comprises a coil, and wherein said magnetic field pattern former comprises a ferrite structure arranged to partially surround said coil and having a gap within and adjacent to which said field pattern is formed.

28. The system defined by claim 27 wherein said target area is not significantly greater than “

P”

.

29. The system defined by claim 27 wherein said target area is not significantly greater than the width of an individual transponder.

30. The system defined by claim 14 including an electric field suppressor located between said magnetic flux generator and said target area.

31. The system defined by claim 30 wherein said magnetic flux generator comprises a coil, and wherein said suppressor comprises a metal shield adapted to suppress an electrical component of an RF wave.

32. The system defined by claim 14 wherein said magnetic field pattern former has a relative permeability greater than 20.

33. 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.

34. The method defined by claim 33 including locating in said magnetic flux field a ferrite structure having a gap, said field pattern being formed within and adjacent to said gap.

35. The method defined by claim 33 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.

36. The method defined by claim 33 including suppressing electric fields associated with said generating of said magnetic flux field, which fields would otherwise reach said target area.

37. 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.

38. The magnetic coupling device of claim 37, wherein the coil is formed as at least a first trace on a printed circuit board.

39. The magnetic coupling device of claim 37, wherein the magnetic field pattern former has a magnetic permeability of at least 20.

40. The magnetic coupling device of claim 39, wherein the magnetic field pattern former is ferrite.

41. The magnetic coupling device of claim 40, 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.

42. The magnetic coupling device of claim 41, wherein the portion of the second side of the coil that is covered by the ferrite is at least 30 percent.

43. The magnetic coupling device of claim 38, further including a first RF shield covering a first side of the coil.

44. The magnetic coupling device of claim 43, wherein the first RF shield has a loop shape with an open circuit.

45. The magnetic coupling device of claim 43, wherein the first RF shield is coupled to an electrical ground.

46. The magnetic coupling device of claim 43, further including a second RF shield covering a second side of the coil.

47. The magnetic coupling device of claim 39, further including a first RF shield covering the first trace;

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

48. The magnetic coupling device of claim 38, further including:

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

49. 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.

50. The magnetic coupling device of claim 49, wherein:

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

51. The magnetic coupling device of claim 49, wherein:

the first RF shield has an open circuit.

52. The magnetic coupling device of claim 49, wherein:

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

53. The magnetic coupling device of claim 52, wherein:

the magnetic field pattern former is flexible ferrite.

54. 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.

55. The method of claim 54, wherein the magnetic field pattern former has a magnetic permeability of at least 20.

56. The method of claim 54, wherein the magnetic field pattern former is flexible ferrite.

57. The method of claim 56, 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.

58. 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.

59. The apparatus of claim 58, further including a printhead arranged to apply indicia upon an outer surface of the transponders.

60. The apparatus of claim 59, wherein the outer surface is a label.

61. The apparatus of claim 58 wherein, the magnetic coupling device is formed as at least a first trace on a printed circuit board.

62. The apparatus of claim 58, wherein the magnetic field pattern former has a magnetic permeability of at least 20.

63. The apparatus of claim 58, wherein the magnetic field pattern former is ferrite.

64. The apparatus of claim 63, 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.

65. The apparatus of claim 64, wherein the portion of the second side of the magnetic coupling device that is covered by the ferrite is at least 30 percent.

66. The apparatus of claim 58, further including a first RF shield covering a first side of the magnetic coupling device.

67. The apparatus of claim 66, wherein the first RF shield has a loop shape with an open circuit.

68. 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.

69. 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.

70. The method of claim 69, wherein the magnetic field pattern former formed from a flexible ferrite material.