Three dimensional RF signatures

• US 20080074270A1
• Filed: 09/22/2006
• Published: 03/27/2008
• Est. Priority Date: 09/22/2006
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Dasylva, Abel, Ashwood-Smith, Peter, Montuno, Delfin Y.
• Granted Patent: US 8,330,601 B2
• Time in Patent Office: Days
• US Class Current: 340/572.7
• CPC Class Codes: G01S 13/758 using a signal generator powered by the interrogation signal
• CPC Class Codes: G01S 5/0247 Determining attitude
• CPC Class Codes: G06K 19/07749 the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card
• CPC Class Codes: G06K 19/07767 the first and second communication means being two different antennas types, e.g. dipole and coil type, or two antennas of the same kind but operating at different frequencies
• 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
• CPC Class Codes: G08B 13/2428 Tag details

Abstract

Three dimensional RF tag signatures may be obtained from a three dimensional RF tag or multiple two or three dimensional RF tags so that information in addition to presence information may be obtained. In one embodiment, a three dimensional RF tag having two or more power coils disposed in non-coplanar planes enables the coils to experience different levels of excitation from an electromagnetic field. This information may be transmitted along with the RF tag response to enable the orientation of the RF tag relative to an RF tag reader to be determined. In another embodiment, multiple RF tags (either standard RF tags or three dimensional RF tags) may be used on a given article and a response signature from the article as a whole may be recorded. The three dimensional response signature thus collected may be compared with previous versions of the response signature to determine if the article has been altered.

Claims

1. A Radio Frequency (RF) tag, comprising:

at least two non-coplanar power coils; and

a circuit connected to the non-coplanar power coils and configured to detect at least one electrical characteristic from at least two of the non-coplanar power coils, and transmit an RF tag code and an indication of the detected electrical characteristics to an RF tag reader.

2. The RF tag of claim 1, wherein the electrical characteristic is at least one of power, current, and voltage.

3. The RF tag of claim 1, wherein the electrical characteristic is the same for each of the at least two non-coplanar power coils.

4. The RF tag of claim 1, wherein the at least two non-coplanar power coils comprise at least three non-coplanar power coils, at least three of which are formed on orthogonal planes.

5. The RF tag of claim 1, wherein power from each of the non-coplanar power coils is used to provide power to the circuit.

6. The RF tag of claim 1, wherein the RF tag is a passive RF tag.

7. A method of obtaining a multidimensional signature from one or more passive Radio Frequency (RF) tags, the method comprising the steps of:

directing electromagnetic radiation at an article or associated group of articles containing the one or more RF tags arranged to provide a three dimensional RF signature; and

receiving a response from the article or group of articles, the response containing the three dimensional RF signature.

8. The method of claim 7, wherein the one or more RF tags comprise an RF tag having a circuit, and at least two non-coplanar power coils, the circuit being connected to the non-coplanar power coils and configured to detect at least one electrical characteristic from at least two of the non-coplanar power coils, and transmit an RF tag code and an indication of the detected electrical characteristics to an RF tag reader.

9. The method of claim 8, further comprising the step of associating the plurality of electrical characteristics with an orientation of the RF tag relative to an RF field in a vicinity of the RF tag.

10. The method of claim 8, wherein the detected electrical characteristic include at least one of power, current, and voltage generated by the non-coplanar power coils when exposed to the electromagnetic radiation.

11. The method of claim 8, wherein the at least two non-coplanar power coils comprise at least three non-coplanar power coils, at least three of which are formed on orthogonal planes.

12. The method of claim 8, further comprising the step of determining from the three dimensional RF signature an orientation of an article associated with the one or more RF tags.

13. The method of claim 8, further comprising the step of determining from the three dimensional RF signature an orientation of an RF tag reader relative to the one or more RF tags.

14. The method of claim 7, wherein the one or more RF tags comprise a plurality of RF tags arranged on the article or group of articles, and wherein the signature depends on the orientation of the RF tags relative to the directed electromagnetic radiation.

15. The method of claim 7, wherein the one or more RF tags comprise a plurality of RF tags arranged on the article or group of articles, and wherein the signature depends on the placement of the RF tags on the article or group of articles.

16. The method of claim 7, wherein the one or more RF tags comprise a plurality of RF tags arranged on the article or group of articles, and wherein the signature depends on the path of motion of the article or group of articles.

17. A method of obtaining a three dimensional signature, the method comprising the steps of:

receiving a first collective response from a first set of tag response signals from a plurality of RF tags associated with an article or a group of articles at a first point in time;

extracting individual tag responses from the first collective response to identify the RF tags associated with the article or group of articles; and

recording the first collective response as a first response signature for the article or group of articles.

18. The method of claim 17, further comprising the steps of:

receiving a second collective response from a second set of tag response signals from the plurality of RF tags associated with the article or group of articles at a second point in time; and

comparing the second collective response with the first response signature.

19. The method of claim 18, further comprising the step of determining from the step of comparing whether any of the RF tags have been moved spatially relative to the other RF tags.

20. The method of claim 19, further comprising the step of interpreting a result of the step of determining as an indication that the article or group of articles has been tampered.