System and method for selective communication with RFID transponders
View Patent ↗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.
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 having a planar coil formed as a trace upon a first layer of a printed circuit board responsive to a radio frequency input signal; and
a magnetic field pattern former configured to collect flux produced by said magnetic flux generator 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 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.
3. The printer defined by claim 1 wherein said magnetic field pattern former comprises a ferrite structure.
4. 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.
5. 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.
6. 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.
7. 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.
8. The printer defined by claim 7 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.
9. The printer defined by claim 7 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.
10. The printer defined by claim 1 including an electric field suppressor located coplanar with the coil between said magnetic flux generator and said target area.
11. The printer defined by claim 10 wherein said suppressor comprises a metal shield formed as a second layer of the printed circuit board covering the planar coil except for an open circuit adapted to suppress eddy currents.
12. The printer defined by claim 1 wherein said magnetic field pattern former has a relative permeability greater than 20.
13. 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;
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; and
an electric field suppressor located between said magnetic flux generator and said 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.
14. The system defined by claim 13 , wherein said flux generator comprises a coil receiving said input signal.
15. The system defined by claim 14 wherein said magnetic field pattern former comprises a ferrite structure arranged to partially surround said coil and having a gap with and adjacent to which said field pattern is formed.
16. The system defined by claim 13 wherein said magnetic field pattern former comprises a ferrite structure.
17. The system defined by claim 13 wherein said system comprises a printer and includes a printhead.
18. The system defined by claim 17 wherein said printhead is positioned and configured to print on or adjacent said transponder while it is still in said target area.
19. The system defined by claim 17 wherein said printhead is positioned and configured to print on or adjacent said transponder when it is outside of said target area.
20. The system defined by claim 13 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.
21. The system defined by claim 20 wherein said target area is not significantly greater than a periodicity “P”.
22. The system defined by claim 13 wherein said target area is not significantly greater than the width of an individual transponder.
23. The system defined by claim 13 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.
24. The system defined by claim 23 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.
25. The system defined by claim 23 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.
26. The system defined by claim 13 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 colt, 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.
27. The system defined by claim 26 wherein said target area is not significantly greater than “P”.
28. The system defined by claim 26 wherein said target area is not significantly greater than the width of an individual transponder.
29. The system defined by claim 13 wherein said magnetic flux generator comprises a planar coil, and wherein said suppressor comprises a metal shield coplanar with and covering said coil; said metal shield having an open circuit adapted to suppress an electrical component of an RF wave.
30. The system defined by claim 13 wherein said magnetic field pattern former has a relative permeability greater than 20.