CAUSING RFID TAGS TO REPLY USING CHANGED REPLY TIMING

• US 20080197979A1
• Filed: 02/21/2008
• Published: 08/21/2008
• Est. Priority Date: 02/21/2007
• Status: Active Grant

• Current Assignee: Impinj, Inc.
• Original Assignee: Impinj, Inc.
• Inventors: Diorio, Christopher J., Kavounas, Gregory T., Enyedy, Arthur Gustav
• Granted Patent: US 8,072,327 B2
• Time in Patent Office: Days
• US Class Current: 340/10.1
• 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: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks

Abstract

RFID reader systems, readers, components, software and methods cause RFID tags to reply using changed reply timing. In a number of embodiments, this timing change is achieved by causing a custom timing command to be transmitted to a tag. In some embodiments, the changed reply timing affects an amount of delay before a tag backscatters a reply.

Claims

1. A component for a Radio Frequency Identification (RFID) reader to communicate with an RFID tag, the tag having received a first command, and backscattered a first reply responsive to the first command, the first reply using a first delay before the tag starts backscattering the first reply after receiving the first command, comprising:

an operational processing block for causing to be transmitted to the tag a custom timing command, the tag then backscattering a second reply that encodes the same functional content as the first reply, the second reply using a second delay before the tag starts backscattering the second reply after receiving a most recent command prior to backscattering the second reply, the second delay different from the first delay responsive to receiving the custom timing command.

2. The component of claim 1, in which

the second reply is identical to the first reply.

3. The component of claim 1, in which

the second reply includes bits more that half of which are arranged similarly to those of the first reply.

4. The component of claim 1, in which

the functional content is one of a code stored in a memory, and a random number.

5. The component of claim 1, in which

the tag is caused to lose power after backscattering the first reply and before receiving the custom timing command.

6. The component of claim 1, in which

the tag is caused to not lose power after backscattering the first reply and before receiving the custom timing command.

7. The component of claim 1, in which

the first command is a command to identify,

the first reply is an identifying reply, and

in which the custom timing command is caused to be transmitted responsive to the identifying reply.

8. The component of claim 1, in which

the most recent command is the custom timing command.

9. The component of claim 1, in which

the most recent command is an intervening command transmitted after the custom timing command.

10. The component of claim 1, in which

a third command is caused to be transmitted to the tag after it has backscattered the second reply, the tag therefore backscattering a third reply using a third delay, the third delay different from the first delay responsive to having received the custom timing command.

11. The component of claim 10, in which

the third delay is substantially the same as the second delay.

12. The component of claim 1, in which

the tag is able to backscatter the second reply using the second delay regardless of what state it is in at the time it receives the custom timing command.

13. The component of claim 1, in which

the tag is in a disabled state where, if it were to receive the custom timing command, the second delay would be the same as the first delay if it were to backscatter the second reply,

the first command is an Enable command caused to be transmitted while the tag is in the disabled state, so as to cause the tag to transition internally to an enabled state, and

the second delay is different from the first delay responsive to receiving the custom timing command while the tag is in the enabled state.

14. The component of claim 13, in which

the Enable command is the Select command of FIG. 9A of this document, and further having a special enable payload, and

the tag further transitions to the enabled state responsive to the Select command having the special enable payload.

15. The component of claim 13, in which

a Disable command is caused to be transmitted to the tag while the tag is in the enabled state, so as to cause the tag to transition internally to the disabled state responsive to receiving the Disable command.

16. The component of claim 15, in which

the Disable command is the Select command of FIG. 9A of this document, and further having a special disable payload, and

the tag further transitions to the disabled state responsive to the Select command having the special disable payload.

17. The component of claim 1, in which

a Tune command is caused to be transmitted to the tag, which encodes a time-indicating parameter, and

the second delay is determined from the time-indicating parameter.

18. The component of claim 1, in which

the Tune command is one of the first command and the custom timing command.

19. An article comprising:

a storage medium, the storage medium having instructions stored thereon, in which when the instructions are executed by at least an RFID reader system component for communicating with an RFID tag, the tag having received a first command, and backscattered a first reply responsive to the first command, the first reply using a first delay before the tag starts backscattering the first reply after receiving the first command, the instructions result in actions comprising;

causing to be transmitted to the tag a custom timing command, the tag then backscattering a second reply that encodes the same functional content as the first reply, the second reply using a second delay before the tag starts backscattering the second reply after receiving a most recent command prior to backscattering the second reply, the second delay different from the first delay responsive to receiving the custom timing command.

20. A method for a Radio Frequency Identification (RFID) reader system component to communicate with an RFID tag, the tag having received a first command, and backscattered a first reply responsive to the first command, the first reply using a first delay before the tag starts backscattering the first reply after receiving the first command, comprising:

causing to be transmitted to the tag a custom timing command, the tag then backscattering a second reply that encodes the same functional content as the first reply, the second reply using a second delay before the tag starts backscattering the second reply after receiving a most recent command prior to backscattering the second reply, the second delay different from the first delay responsive to receiving the custom timing command.

21. The method of claim 20, in which

the tag is caused to lose power after backscattering the first reply and before receiving the custom timing command.

22. The method of claim 20, in which

the tag is caused to not lose power after backscattering the first reply and before receiving the custom timing command.

23. The method of claim 20, in which

the most recent command is the custom timing command.

24. The method of claim 20, in which

the most recent command is an intervening command transmitted after the custom timing command.

25. The method of claim 20, in which

a Tune command is caused to be transmitted to the tag, which encodes a time-indicating parameter, and

the second delay is determined from the time-indicating parameter.