DEVICE FOR LOCATING OBJECTS BY RFID COMMUNICATION

• US 20110133889A1
• Filed: 12/07/2010
• Published: 06/09/2011
• Est. Priority Date: 12/08/2009
• Status: Active Grant

• Current Assignee: Commissariat a L'Energie Atomique (AES Corporation)
• Original Assignee: Commissariat a L'Energie Atomique (AES Corporation)
• Inventors: THOMAS, Thierry
• Granted Patent: US 8,928,460 B2
• Time in Patent Office: Days
• US Class Current: 340/8.1
• CPC Class Codes: G06K 17/00 Methods or arrangements for effecting co-operative working between equipments covered by two or more of main groups G06K1/00 - G06K15/00, e.g. automatic card files incorporating conveying and reading operations
• 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 7/10079 the collision being resolved in the spatial domain, e.g. temporary shields for blindfolding the interrogator in specific directions

Abstract

The invention relates to the locating and identifying of objects with radiofrequency communication by inductive coupling, without electrical contact, between a reader and a tag. The device includes an array of N fixed RFID markers of RFID tag type, with inductive antennas placed at known positions, N being an integer greater than 1 and an RFID tag reader provided with a fixed reading inductive antenna passing in proximity to the N markers. The position of the N markers with respect to the inductive reading antenna is such that the mutual inductance between the inductive antenna of any marker and the inductive reading antenna is zero when no object to be located is present in the vicinity of the array of markers, and nonzero when an RFID tag is present in the vicinity of the marker considered. A coupling is established in the presence of a mobile tag in proximity to a marker.

Claims

1. A device for locating objects including an electronic tag of radiofrequency identification (RFID) type having an inductive antenna, the device comprising:

an array of N fixed RFID tags including one of inductive antennas and markers, placed at known positions, N being an integer greater than 1; and

an RFID tag reader including a fixed reading inductive antenna passing in proximity to the N antennas of the N markers,

wherein the configuration of the inductive reading antenna with respect to the positions of the N antennas of the N markers is such that the mutual inductance between the inductive antenna of any marker and the inductive reading antenna is zero.

2. The device according to claim 1, wherein the array of markers is organized into rows passing through the centres of the antennas of the markers, the array defining zones situated between the rows, the device further comprising means for receiving data for several markers whose antennas bracket a zone in which the object is placed.

3. The device according to claim 2, wherein the array of rows is organized into regularly distributed rows and columns.

4. The device according to claim 1, further comprising at least two independent reading pathways each comprising a respective reading antenna.

5. The device according to claim 4, wherein the N markers of the marker array are divided into groups, each group being associated with at least one respective reading pathway, the antennas of the markers of one and the same group being in zero mutual inductance with the reading antenna of the reading pathway associated with this group.

6. The device according to claim 5, wherein the configurations of the antennas of the reading pathways delimit partly overlapping areas in a plane.

7. The device according to claim 5, wherein the configurations of the antennas of the reading pathways delimit disjoint areas in a plane.

8. The device according to claim 1, wherein the RFID reader is able to interrogate the RFID tags affixed to objects to be located as well as the markers, and able to receive an identification of these RFID tags situated in proximity to the array of markers and an identification of the markers having a nonzero electromagnetic coupling with the reading antenna on account of their nonzero inductive coupling with the RFID tags.

9. The device according to claim 1, wherein the markers are able to detect and analyse identification information for the tags.

10. The device according to claim 1, wherein the markers are able to retransmit towards the reader an item of information relating to the identification of the tags associated with the objects to be located, with which tags these markers have a nonzero inductive coupling.

11. The device according to claim 1, wherein the RFID reader is able to operate for various levels of radiofrequency field.

12. The device according to claim 2, comprising at least two independent reading pathways each comprising a respective reading antenna.

13. The device according to claim 12, wherein the N markers of the marker array are divided into groups, each group being associated with at least one respective reading pathway, the antennas of the markers of one and the same group being in zero mutual inductance with the reading antenna of the reading pathway associated with this group.

14. The device according to claim 13, wherein the configurations of the antennas of the reading pathways delimit partly overlapping areas in a plane.

15. The device according to claim 13, wherein the configurations of the antennas of the reading pathways delimit disjoint areas in a plane.

16. The device according to claim 2, wherein the RFID reader is able to interrogate the RFID tags affixed to objects to be located as well as the markers, and able to receive an identification of these RFID tags situated in proximity to the array of markers and an identification of the markers having a nonzero electromagnetic coupling with the reading antenna on account of their nonzero inductive coupling with the RFID tags.

17. The device according to claim 3, comprising at least two independent reading pathways each comprising a respective reading antenna.

18. The device according to claim 17, wherein the N markers of the marker array are divided into groups, each group being associated with at least one respective reading pathway, the antennas of the markers of one and the same group being in zero mutual inductance with the reading antenna of the reading pathway associated with this group.

19. The device according to claim 18, wherein the configurations of the antennas of the reading pathways delimit partly overlapping areas in a plane.

20. The device according to claim 3, wherein the RFID reader is able to interrogate the RFID tags affixed to objects to be located as well as the markers, and able to receive an identification of these RFID tags situated in proximity to the array of markers and an identification of the markers having a nonzero electromagnetic coupling with the reading antenna on account of their nonzero inductive coupling with the RFID tags.