RFID TAG CHIPS AND TAGS REFRAINING FROM PARTICIPATING IN A SUBSEQUENT INVENTORYING ATTEMPT AND METHODS

• US 20080258916A1
• Filed: 03/28/2008
• Published: 10/23/2008
• Est. Priority Date: 03/29/2007
• Status: Active Grant

• Current Assignee: Impinj, Inc.
• Original Assignee: Impinj, Inc.
• Inventors: Diorio, Christopher J., Aiouaz, Ali, Dietrich, Paul, Rahimi, Kambiz, Stanford, Theron, Lindhorst, Chad, Esterberg, Aanand
• Granted Patent: US 8,279,045 B2
• Time in Patent Office: Days
• US Class Current: 340/572.1
• 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: G06K 7/10039 interrogator driven, i.e. synchronous
• CPC Class Codes: G06Q 10/087 Inventory or stock management, e.g. order filling, procurement or balancing against orders

Abstract

RFID tags and chips for RFID tags are capable of being inventoried in one or more early attempts. These tags are capable of then refraining from participating in one or more subsequent inventorying attempts. In some embodiments refraining is performed solely by the tag, while in others it is guided by the RFID reader. In some embodiments, an inventoried indicator in the tag becomes updated upon backscattering. The updated value is used by the tag to recognize a subsequent attempt, and thus refrain from participating in it. This permits the subsequent attempt to be used more intensively for inventorying the more elusive, harder-to-read tags, especially in more demanding scenarios.

Claims

1. An Integrated Circuit (IC) chip for use with a Radio Frequency Identification (RFID) tag having an antenna, comprising:

a memory for storing a code, an inventoried flag capable of being flipped between two states, and an inventoried indicator; and

a processing block for coupling with the antenna and operable to;

detect a first attempt to read the code, the first attempt agreeing with a current state of the inventoried flag,

cause the code to be backscattered responsive to the first attempt,

update the inventoried indicator in conjunction with causing the code to be backscattered,

one of;

flip and not flip the state of the inventoried flag responsive to the first attempt,

then detect a second attempt to read the code, the second attempt agreeing with a current state of the inventoried flag, and

cause the code to be backscattered responsive to the second attempt if the updated inventoried indicator meets a participation condition, else not causing the code to be backscattered.

2. The IC chip of claim 1, in which

nothing is caused to be backscattered responsive to the second attempt, if the updated inventoried indicator does not meet the participation condition.

3. The IC chip of claim 1, in which

an error code is caused to be backscattered responsive to the second attempt, if the updated inventoried indicator does not meet the participation condition.

4. The IC chip of claim 1, in which

the tag becomes further singulated from a population of tags during the first attempt so as to cause the code to be backscattered, and

in which the inventoried indicator is updated responsive to becoming singulated.

5. The IC chip of claim 1, in which

updating the inventoried indicator caused the participation condition to no longer be met.

6. The IC chip of claim 1, in which

the updated inventoried indicator does not meet the participation condition during the second attempt,

the inventoried indicator later becomes reset so that it meets the participation condition.

7. The IC chip of claim 6, in which the processing block is further operable to:

then detect a third attempt to read the code, the third attempt agreeing with a current state of the inventoried flag; and

cause the code to be backscattered responsive to the third attempt and to the updated inventoried indicator meeting the participation condition.

8. The IC chip of claim 6, in which

the inventoried indicator becomes reset after a preset time elapses from an event.

9. The IC chip of claim 6, in which

the inventoried indicator becomes reset responsive to receiving wirelessly a suitable Reset command.

10. The IC chip of claim 1, in which

power has not been lost in the tag after the inventoried indicator is updated and before the second attempt is detected.

11. The IC chip of claim 1, in which

power has been lost and regained in the tag after the inventoried indicator is updated and before the second attempt is detected.

12. The IC chip of claim 1, in which

a first serial number is received in association with the first attempt,

the inventoried indicator is updated by being set to a new value that is determined from the first serial number, and

the participation condition refers to whether the updated inventoried indicator differs from the new value.

13. The IC chip of claim 12, in which

the new value is equal to the first serial number.

14. The IC chip of claim 12, in which

the first serial number is received via one of:

a Select command and a BlockWrite command of the Gen2 Spec.

15. The IC chip of claim 12, in which

a second serial number is further received in association with the second attempt, and

the inventoried indicator is updated further from the second serial number.

16. The IC chip of claim 1, in which

the inventoried indicator includes a number stored in a counter,

updating is performed by adjusting the number in the counter, and

the participation condition is that the number in the counter has not reached a limit.

17. The IC chip of claim 16, in which

the number in the counter is adjusted by being decremented.

18. The IC chip of claim 16, in which

the limit is zero.

19. The IC chip of claim 16, in which

a participation parameter is received wirelessly, and

at least one of a number initially stored in the counter and the limit is determined from the received participation parameter.

20. The IC chip of claim 16, in which

the participation parameter is received via one of:

a Select command and a BlockWrite command of the Gen2 Spec.

21. A Radio Frequency Identification (RFID) tag, comprising:

an antenna;

a memory for storing a code, an inventoried flag capable of being flipped between two states, and an inventoried indicator; and

a processing block coupled with the antenna and operable to;

detect a first attempt to read the code, the first attempt agreeing with a current state of the inventoried flag,

cause the code to be backscattered responsive to the first attempt,

update the inventoried indicator in conjunction with causing the code to be backscattered,

one of;

flip and not flip the state of the inventoried flag responsive to the first attempt,

then detect a second attempt to read the code, the second attempt agreeing with a current state of the inventoried flag, and

cause the code to be backscattered responsive to the second attempt if the updated inventoried indicator meets a participation condition, else not causing the code to be backscattered.

22. A method for a Radio Frequency Identification (RFID) tag storing a code, an inventoried flag capable of being flipped between two states, and an inventoried indicator, comprising:

detecting a first attempt to read the code, the first attempt agreeing with a current state of the inventoried flag;

backscattering the code responsive to the first attempt;

updating the inventoried indicator in conjunction with backscattering the code;

one of;

flipping and not flipping the state of the inventoried flag responsive to the first attempt;

then detecting a second attempt to read the code, the second attempt agreeing with a current state of the inventoried flag; and

backscattering the code responsive to the second attempt if the updated inventoried indicator meets a participation condition, else not backscattering the code.

23. The method of claim 22, in which

the updated inventoried indicator does not meet the participation condition during the second attempt,

the inventoried indicator later becomes reset so that it meets the participation condition.

24. The method of claim 22, in which

a first serial number is received in association with the first attempt,

the inventoried indicator is updated by being set to a new value that is determined from the first serial number, and

the participation condition refers to whether the updated inventoried indicator differs from the new value.

25. The method of claim 22, in which

the inventoried indicator includes a number stored in a counter,

updating is performed by adjusting the number in the counter, and

the participation condition is that the number in the counter has not reached a limit.