Device for locating objects by RFID communication

Patent metadata

Field	Value
Publication number	US-8928460-B2
Application number	US-96176010-A
Country	US
Kind code	B2
Filing date	Dec 7, 2010
Priority date	Dec 8, 2009
Publication date	Jan 6, 2015
Grant date	Jan 6, 2015

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.

First claim

What is claimed is:

1. A device for determining a position, with respect to known fixed positions, of an object provided with an electronic radiofrequency identification (RFID) tag having an inductive antenna, the device comprising:
an array of N fixed RFID tags each provided with a respective inductive antenna, said N fixed RFID tags placed at said known fixed positions with respective each other, N being an integer greater than 1; and
an RFID tag reader provided with a fixed inductive reading antenna passing in proximity to the N respective inductive antennas of the N fixed RFID tags,
a configuration of the fixed inductive reading antenna with respect to each of the N antennas of the N fixed RFID tags being such that the mutual inductance between the inductive antenna of any one of the N fixed RFID tags and the inductive reading antenna is zero in the absence of the object, and
means for determining a proximity of the object to a given fixed RFID tag from a non-zero coupling between said given fixed RFID tag and the inductive reading antenna, said non-zero coupling induced by a proximity between the inductive antenna of the RFID tag of the object, the inductive antenna of said given fixed RFID tag and the inductive reading antenna of the reader,
wherein the array of fixed RFID tags is organized into rows linking centres of the antennas of the fixed RFID tags, the array defining zones situated between the rows, the device further comprising means for receiving data from several RFID tags whose antennas bracket a zone in which the object is placed.

2. The device according to claim 1 , wherein the array of rows is organized into regularly distributed rows and columns.

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

4. The device according to claim 3 , wherein the N RFID tags of the array are divided into groups, each group being associated with at least one respective reading pathway, the antennas of the RFID tags of one and the same group being in zero mutual inductance with the respective reading antenna of the reading pathway associated with this group.

5. The device according to claim 4 , wherein the configurations of the respective reading antenna of one reading pathway delimit a planar area which is partly overlapping with an area delimited by the respective reading antenna of another reading pathway.

6. The device according to claim 2 , wherein the RFID reader is able to interrogate the RFID tag of said object to be located and the N fixed RFID tags, and able to receive an identification of said RFID tag of said object when said object is situated in proximity to the array of fixed RFID tags and an identification of those RFID tags among the N fixed RFID tags that have a nonzero electromagnetic coupling with the reading antenna on account of their nonzero inductive coupling with said RFID tag of said object.

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

8. The device according to claim 7 , wherein the N RFID tags of the array are divided into groups, each group being associated with at least one respective reading pathway, the antennas of the fixed RFID tags of one and the same group being in zero mutual inductance with the respective reading antenna of the reading pathway associated with this group.

9. The device according to claim 8 , wherein the configurations of the respective reading antenna of one reading pathway delimit a planar area which is partly overlapping with an area delimited by the respective reading antenna of another reading pathway.

10. The device according to claim 8 , wherein the configurations of the reading antennas of the reading pathways delimit disjoint areas in a plane.

11. The device according to claim 1 , wherein the RFID reader is able to interrogate the RFID tag of said object to be located and the N fixed RFID tags, and able to receive an identification of said RFID tag when the object is situated in proximity to the array of fixed RFID tags and an identification of those RFID tags among the N fixed RFID tags that have a nonzero electromagnetic coupling with the reading antenna on account of their nonzero inductive coupling with said RFID tag of said object.

12. The device according to claim 1 , wherein the fixed RFID tags are able to detect and analyse identification information from the tags of said object to be located.

13. The device according to claim 1 , wherein the fixed RFID tags are able to retransmit towards the reader an item of information relating to the identification of the tag of said object to be located, with which tag these fixed RFID tags have a nonzero inductive coupling.

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

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

16. The device according to claim 15 , wherein the N fixed RFID tags of the array are divided into groups, each group being associated with at least one respective reading pathway, the antennas of the RFID tags of one and the same group being in zero mutual inductance with the respective reading antenna of the reading pathway associated with this group.

17. The device according to claim 16 , wherein the configurations of the respective reading antenna of one reading pathway delimit a planar area which is partly overlapping with an area delimited by the respective reading antenna of another reading pathway.

18. The device according to claim 16 , wherein the configurations of the reading antennas of the reading pathways delimit disjoint areas in a plane.

19. The device according to claim 1 , wherein the RFID reader is able to interrogate the RFID tag of said object to be located and the N fixed RFID tags, and able to receive an identification of said RFID tag of said object when the object is situated in proximity to the array of fixed RFID tags and an identification of those RFID tags among the N fixed RFID tags that have a nonzero electromagnetic coupling with the reading antenna on account of their nonzero inductive coupling with said RFID tag of said object.

Assignees

• Thomas Thierry
• Commissariat Energie Atomique

Inventors

• Thomas Thierry

Classifications

• G06K7/0008 Primary

  General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer · CPC title

• G06K7/10079

  the collision being resolved in the spatial domain, e.g. temporary shields for blindfolding the interrogator in specific directions · CPC title

• G06K17/00

  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 title

• G06K2017/0045

  Physics · mapped topic