Method and Apparatus Pertaining to Radio-Frequency Identification Tags

• US 20120274449A1
• Filed: 02/16/2012
• Published: 11/01/2012
• Est. Priority Date: 04/27/2011
• Status: Active Grant

• Current Assignee: Walmart Apollo, LLC (WalMart Inc.)
• Original Assignee: Wal-Mart Stores Texas LLC (WalMart Inc.)
• Inventors: Wilkinson, Bruce W.
• Granted Patent: US 9,892,358 B2
• Time in Patent Office: Days
• US Class Current: 340/10.1
• CPC Class Codes: G01S 11/06 using intensity measurements
• CPC Class Codes: G01S 13/751 wherein the responder or reflector radiates a coded signal
• CPC Class Codes: G01S 13/767 Responders; Transponders teaching or practice apparatus for gun-aiming or gun-laying using reflecting targets or active targets F41G3/26
• CPC Class Codes: G01S 13/825 with exchange of information between interrogator and responder
• CPC Class Codes: G06K 19/0712 the arrangement being capable of triggering distinct operating modes or functions dependent on the strength of an energy or interrogation field in the proximity of the record carrier active means for hindering electromagnetic reading or writing G06K19/07336
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
• CPC Class Codes: H05K 999/99 dummy group

Abstract

A presently-powered RFID tag can itself determine its own relative movement with respect to a reader. This RFID tag can responsively alter its read state to thereby permit the RFID tag to respond to a subsequent read inquiry. By one approach the RFID tag assesses its own movement by monitoring the strength of its received power. By another approach, the RFID tag has a power source that becomes electrically charged via radio-frequency energy received by the tag antenna and that power source is configured to become operably discharged at a point in time that corresponds to a typical null-sensing duration of time for a given application setting for that RFID tag.

Claims

1. A radio-frequency identification (RFID) tag configured to unilaterally seek to detect its own motion relative to its environment.

2. The RFID tag of claim 1 wherein the RFID tag seeks to detect its own motion relative to its environment by sensing at least one circumstance that evidences movement with respect to at least one RFID-tag reader.

3. The RFID tag of claim 2 wherein the at least one circumstance comprises an indication of received signal strength.

4. The RFID tag of claim 3 wherein the received signal strength comprises the received signal strength of a signal as transmitted by the RFID-tag reader.

5. The RFID tag of claim 2 wherein the at least one circumstance comprises a null in RFID-tag reader transmissions.

6. The RFID tag of claim 5 wherein the null in RFID-tag transmissions comprises a null having a duration of time that corresponds to a typical null-sensing duration of time for a given application setting for the RFID tag.

7. The RFID tag of claim 6 wherein the null-sensing duration of time comprises a duration of time in a range from about three seconds to about five seconds.

8. The RFID tag of claim 6 wherein the null-sensing duration of time corresponds to a typical time that a person carrying the RFID tag will be in a radio-frequency null when walking at a typical rate through a multi-RFID tag reader application setting.

9. The RFID tag of claim 1 wherein the RFID tag is further configured to unilaterally change its own read state in response to detecting its own motion relative to its environment.

13. The RFID tag of claim 1 further comprising:

a control circuit configured to use a specific reader-response state upon regaining power.

14. The RFID tag of claim 13 wherein the specific reader-response state comprises a specific inventory state per the Electronic Product Code (EPC) Radio-Frequency Identity Protocols Class-1 Generation-2 Ultra-High Frequency (UHF) RFID Protocol for Communications at 860 MHz-960 MHz Version 1.0.9 (EPC GEN2).

15. The RFID tag of claim 14 wherein the specific inventory state comprises inventory state B.

10. A radio-frequency identification (RFID) tag configured to unilaterally change its own read state other than in response to a mere passage of time and other than in response to merely powering up.

11. The RFID tag of claim 10 wherein the RFID tag is configured to unilaterally change its own read state as a function of information that tends to indicate movement of the RFID tag.

12. The RFID tag of claim 11 wherein the information comprises information regarding signal strength as pertains to a signal received from a reader.