Method and device for reading radio frequency identification (RFID) tags

• US 8,416,060 B2
• Filed: 12/08/2009
• Issued: 04/09/2013
• Est. Priority Date: 12/08/2009
• Status: Active Grant

• Current Assignee: Symbol Technologies, LLC (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: Strzelczyk, Martin, Connolly, Sean, Duron, Mark
• Primary Examiner(s): Mehmood, Jennifer
• Assistant Examiner(s): WILSON, BRIAN P
• Application Number:
  US12/632,833
• Publication Number:
  US 20110133901A1
• Time in Patent Office: 1,218 Days
• Field of Search: None
• 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
• CPC Class Codes: H04Q 2213/13095 PIN / Access code, authentication

Abstract

A method and device enables reading radio frequency identification (RFID) tags in a localized area. The method according to one embodiment includes commencing transmission of an interference signal from a reader device (step 505). A command signal is then transmitted from the device while the interference signal is still being transmitted (step 510). The command signal instructs non-target RFID tags to not respond to an interrogation signal, and the target RFID tags do not process the command signal because the command signal is blocked by the interference signal. Transmission of the interference signal from the device is then stopped (step 515). The interrogation signal is then transmitted from the device after the interference signal is no longer being transmitted (step 520). Finally, a response signal is received at the device from the target RFID tags that enables the device to read only the target RFID tags (step 525).

Claims

1. A method for reading a target radio frequency identification (RFID) tag at an RFID reader device, the method comprising:

commencing transmission of an interference signal from the reader device;

transmitting a do not respond command signal from the reader device while the interference signal is still being transmitted, whereby the do not respond command signal instructs non-target RFID tags to not respond to an interrogation signal, and wherein the target RFID tag does not process the do not respond command signal because the do not respond command signal is blocked by the interference signal;

stopping transmission of the interference signal from the reader device;

transmitting the interrogation signal from the reader device after the interference signal is no longer being transmitted; and

receiving a response signal at the reader device from the target RFID tag that enables the reader device to read the target RFID tag

wherein RFID tags respond to the interrogation signal unless a do not respond command signal has been received by the RFID tag.

2. The method of claim 1, wherein the interrogation signal is transmitted at a higher power level than the interference signal.

3. The method of claim 1, wherein after the interrogation signal is transmitted a plurality of response signals are received at the reader device from a plurality of target RFID tags.

4. The method of claim 1, wherein the do not respond command signal comprises a Select command that conforms to an Electronic Product Code (EPC) Class 1 Generation 2 Ultra High Frequency (UHF) Air Interface Protocol Standard.

5. The method of claim 4, wherein in the Select command comprises a specific, low-probability match field.

6. The method of claim 1, wherein the interference signal, do not respond command signal, interrogation signal, and response signal are all within the range of 860MHz to 960MHz or 2400MHz to 2483.5MHz.

7. A method for reading target radio frequency identification (RFID) tags at an RFID reader device, the method comprising:

commencing transmission of an interference signal from the reader device;

transmitting a first interrogation signal from the reader device while the interference signal is still being transmitted, wherein the interference signal interferes with the first interrogation signal;

receiving at the reader device, in response to the first interrogation signal, a plurality of first response signals from a first set of non-target RFID tags;

stopping transmission of the interference signal from the reader device;

transmitting a second interrogation signal from the reader device after transmission of the interference signal stops;

receiving at the reader device, in response to the second interrogation signal, a plurality of second response signals from a second set of non-target and target RFID tags; and

reading the target RFID tags by processing at the RFID reader device response signals from RFID tags included only in the second set and not in the first set;

wherein RFID tags respond to the interrogation signal unless they have been interfered with by the interference signal.

8. The method of claim 7, wherein the first set can be defined as set B, the second set can be defined as set A∪

B, and the target RFID tars consist of set A, wherein A=A∪

B−

((A∪

B) ∩

B).

9. A reader device for reading a target radio frequency identification (RFID) tag, the device comprising:

a transceiver; and

a processor operatively coupled to the transceiver and to a memory, wherein the memory includes;

computer readable program code components for commencing transmission of an interference signal from the transceiver;

computer readable program code components for transmitting a do not respond command signal from the transceiver while the interference signal is still being transmitted, whereby the do not respond command signal instructs non-target RFID tags to not respond to an interrogation signal, and whereby the target RFID tag does not process the do not respond command signal because the do not respond command signal is blocked by the interference signal;

computer readable program code components for stopping transmission of the interference signal from the transceiver;

computer readable program code components for transmitting the interrogation signal from the transceiver after the interference signal is no longer being transmitted; and

computer readable program code components for receiving a response signal at the transceiver from the target RFID tag that enables the reader device to read the target RFID tag;

wherein RFID tags respond to the interrogation signal unless a do not respond command signal has been received by the RFID tag.

10. The device of claim 9, wherein the interrogation signal is transmitted at a higher power level than the interference signal.

11. The device of claim 9, wherein after the interrogation signal is transmitted a plurality of response signals are received at the reader device from a plurality of target RFID tags.

12. The device of claim 9, wherein the do not respond command signal comprises a Select command that conforms to an Electronic Product Code (EPC) Class 1 Generation 2 Ultra High Frequency (UHF) Air Interface Protocol Standard.

13. The device of claim 12, wherein in the Select command comprises a specific, low-probability match field.

14. The device of claim 9, wherein the interference signal, do not respond command signal, interrogation signal, and response signal are all within the range of 860MHz to 960MHz or 2400MHz to 2483.5MHz.

15. The device of claim 9, further comprising a first antenna for transmitting the do not respond command signal and a second antenna for transmitting the interference signal.

16. The device of claim 15, wherein the first antenna and the second antenna are not co-located.