INTERROGATING RADIO FREQUENCY TAGS

• US 20080150692A1
• Filed: 06/22/2007
• Published: 06/26/2008
• Est. Priority Date: 06/22/2006
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: Sirit Technologies, Inc.
• Inventors: Cruickshanks, George D., Lin, Steven C., Missimer, David Ross, Frederick, Thomas J.
• Granted Patent: US 8,228,173 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: G06K 7/10039 interrogator driven, i.e. synchronous

Abstract

The present disclosure is directed to a system and method for interrogating radio frequency tags. In some implementations, a method includes A method includes successively polling, for a specified number of inventory cycles, a plurality of Radio Frequency Identification (RFID) tags in a first state. At least a first subset of the plurality of RFID tags transitions from the first state to a second state in response to the poll. After the specified number of inventory cycles, a command is transmitted to update at least a second subset of the plurality of RFID tags from the second state to first state. The plurality of RFID tags are subsequently polled after transmitting the update command.

Claims

1. A method, comprising:

successively polling, for a specified number of inventory cycles, a plurality of Radio Frequency Identification (RFID) tags in a first state, wherein at least a first subset of the plurality of RFID tags transitions from the first state to a second state in response to the poll;

transmitting, after the specified number of inventory cycles, a command to update at least a second subset of the plurality of RFID tags from the second state to first state; and

subsequently polling the plurality of RFID tags after transmitting the update command.

2. The method of claim 1, wherein the polling is transmitted in accordance with an A only singulation.

3. The method of claim 1, wherein the command comprises a select command in accordance with EPC Global Class-1 Generation-2 protocol.

4. The method of claim 1, further comprising dynamically adjusting an initial inventory frame size associated with each inventory cycle based, at least in part, on responses to the polls.

5. The method of claim 1, further comprising dynamically updating, prior to resetting tags from the second state to the first state, the specified number of inventory cycles based, at least in part, on responses to the polls.

6. The method of claim 1, wherein the update is based, at least in part, on an estimate of a number of new RFID tags expected in each inventory cycle.

7. A method for interrogating RFID tags, comprising:

transmitting requests to a plurality of RFID tags for information associated with RFID tags in a specified state; and

dynamically switching between a first singulation algorithm and a second singulation algorithm based, at least in part, on responses to the requests.

8. The method of claim 7, the first singulation algorithm comprising an A only singulation algorithm, the second singulation algorithm comprising an ABA singulation algorithm.

9. The method of claim 7, wherein the first singulation algorithm is associated with a select period for executing the first singulation algorithm, the method further comprising dynamically adjusting the select period based, at least in part, on the responses to the requests.

10. The method of claim 9, further comprising:

successively executing the first singulation algorithm for the select period; and

executing the second singulation algorithm in response to at least the select period being satisfied.

11. A method comprising:

successively reading a plurality of RFID tags in a predetermined state by each one of a plurality of antennas, each antenna performing an inventory round at each read; and

issuing a select command by each one of the plurality of antennas every P inventory rounds.

12. The method of claim 11, wherein Pisa number not divisible by a number of antennas.

13. A method of reading a plurality of RFID tags affixed to goods placed on a pallet and passing through an interrogation zone equipped with RFID antennas comprising:

successively reading, by the RFID antennas a subset of the plurality of RFID tags in a predetermined session state, each reading by all antennas being an inventory cycles;

completing a predetermined number of inventory cycles by the antennas;

issuing a select command by one of the antennas in response to completing the predetermined number of inventory cycles, the select command causing a subset of the plurality of RFID tags to switch to the predetermined session state; and

repeating the above steps.

14. A system comprising:

a plurality of RFID antennas disposed about an interrogation zone;

means for successively reading a plurality of RFID tags in a predetermined session state passing by the plurality of RFID antennas by each one of a plurality of antennas, each antenna performing an inventory round at each read; and

means for issuing a select command by each one of the plurality of antennas every P inventory rounds and causing at least one of the plurality of RFID tags to switch to the predetermined session state.

15. An RFID reader, comprising:

a plurality of RF antennas configured to generate an interrogation zone; and

a controller configured to;

successively poll, for a specified number of inventory cycles, a plurality of Radio Frequency Identification (RFID) tags in a first state, wherein at least a first subset of the plurality of RFID tags transitions from the first state to a second state in response to the poll,

transmit, after the specified number of inventory cycles, a command to update at least a second subset of the plurality of RFID tags from the second state to first state; and

subsequently poll the plurality of RFID tags after transmitting the update command.

16. The reader of claim 15, wherein the polling is transmitted in accordance with an A only singulation.

17. The reader of claim 15, wherein the command comprises a select command in accordance with EPC Global Class-1 Generation-2 protocol.

18. The reader of claim 15, further comprising dynamically adjusting an initial inventory frame size associated with each inventory cycle based, at least in part, on responses to the polls.

19. The reader of claim 15, further configured to dynamically update, prior to resetting tags from the second state to the first state, the specified number of inventory cycles based, at least in part, on responses to the polls.

20. The reader of claim 15, wherein the update is based, at least in part, on an estimate of a number of new RFID tags expected in each inventory cycle.

21. An RFID reader, comprising:

a plurality of RF antennas configured to generate an interrogation zone; and

a controller configured to;

transmit requests to a plurality of RFID tags for information associated with RFID tags in a specified state; and

dynamically switch between a first singulation algorithm and a second singulation algorithm based, at least in part, on responses to the requests.

22. The reader of claim 21, the first singulation algorithm comprising an A only singulation algorithm, the second singulation algorithm comprising an ABA singulation algorithm.

23. The reader of claim 21, wherein the first singulation algorithm, is associated with a select period for executing the first singulation algorithm, the reader further configured to dynamically adjust the select period based, at least in part, on the responses to the requests.

24. The reader of claim 23, further configured to:

successively execute the first singulation algorithm for the select period; and

execute the second singulation algorithm in response to at least the select period being satisfied.