RFID tag with programmable read range

• US 20070273481A1
• Filed: 05/25/2006
• Published: 11/29/2007
• Est. Priority Date: 05/25/2006
• Status: Abandoned Application

• Current Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: Soleimani, Mohammad
• Application Number:
  US11/440,094
• Publication Number:
  US 20070273481A1
• Time in Patent Office: Days
• US Class Current: 340/10.100
• CPC Class Codes: H01Q 1/2225 used in active tags, i.e. provided with its own power source or in passive tags, i.e. deriving power from RF signal

Abstract

A system and method in a radio frequency identification (RFID) tag for responding to RFID reader communication signals is described. A strength of a signal from a reader is measured. A RFID read signal is received from the reader. A response to the read signal is enabled based on the measured strength.

Claims

1. A method in a radio frequency identification (RFID) tag for responding to RFID reader communication signals, comprising:

measuring a strength of a signal from a reader;

receiving a RFID read signal from the reader; and

enabling a response to the read signal based on the measured strength.

2. The method of claim 1, further comprising:

if the response is enabled;

selecting a data object based on the measured signal strength, and

transmitting a response to the read signal that includes the data object.

3. The method of claim 2, wherein said selecting comprises:

selecting a data object from a plurality of data objects based on the measured signal strength.

4. The method of claim 2, wherein said selecting comprises:

selecting a data object if the measured signal strength is greater than a threshold signal strength value.

5. The method of claim 2, wherein said selecting comprises:

selecting a data object if the measured signal strength is less than a threshold signal strength value.

6. The method of claim 2, wherein said selecting comprises:

selecting a data object if the measured signal strength is greater than a first threshold signal strength value and is less than a second threshold signal strength value.

7. The method of claim 1, further comprising:

selecting a dummy data object due to the measured signal strength.

8. The method of claim 1, further comprising:

if the response is not enabled, inhibiting a response to the read signal.

9. The method of claim 1, further comprising:

measuring a duration of time over which the measured strength is greater than a threshold signal strength value.

10. The method of claim 9, wherein said enabling comprises:

enabling a response to the read signal if the measured duration of time is greater than a threshold time value.

11. The method of claim 10, further comprising:

programming the threshold time value into the RFID tag.

12. The method of claim 1, further comprising:

programming a threshold signal strength value into the RFID tag.

13. A radio frequency identification (RFID) tag, comprising:

means for measuring a strength of a signal from a reader;

means for receiving a RFID read signal from the reader; and

means for enabling a response to the read signal based on the measured strength.

14. A radio frequency identification (RFID) tag, comprising:

an antenna;

a signal strength monitor module configured to measure a strength of a signal received at the antenna from a reader;

a demodulator configured to receive a RFID read signal from the reader; and

a response enable module configured to enable a response to the read signal based on the measured strength.

15. The RFID tag of claim 14, further comprising:

a modulator coupled to the antenna;

wherein the modulator is configured to modulate a response to the read signal onto a radio frequency signal if enabled by the response enable module.

16. The RFID tag of claim 14, further comprising:

a substrate; and

an integrated circuit (IC) die mounted to the substrate, wherein the signal strength monitor module, demodulator, and response enable module are in the IC die;

wherein the antenna is formed on the substrate.

17. The RFID tag of claim 14, wherein the response enable module is configured to enable selection of a stored data object based on the measured signal strength.

18. The RFID tag of claim 14, wherein the response enable module comprises a comparator that compares the measured signal strength to a threshold signal strength value.

19. The RFID tag of claim 14, wherein the response enable module is configured to enable selection of a stored data object from a plurality of stored data objects based on the measured signal strength.

20. The RFID tag of claim 14, wherein the response enable module is configured to enable selection of a stored data object if the measured signal strength is greater than a stored threshold signal strength value.

21. The RFID tag of claim 14, wherein the response enable module is configured to enable selection of a stored data object if the measured signal strength is less than a stored threshold signal strength value.

22. The RFID tag of claim 14, wherein the response enable module is configured to enable selection of a stored data object if the measured signal strength is greater than a stored threshold signal strength value.

23. The RFID tag of claim 14, wherein the response enable module is configured to enable selection of a stored data object if the measured signal strength is greater than a first stored threshold signal strength value and is less than a second stored threshold signal strength value.

24. The RFID tag of claim 14, wherein the response enable module is configured to enable selection of a stored dummy data object based on the measured signal strength.

25. The RFID tag of claim 14, wherein the response enable module is configured to inhibit a response to the read signal based on the measured strength.

26. The RFID tag of claim 14, further comprising:

a timer module configured to measure a duration of time over which the measured strength is greater than a stored threshold signal strength value.

27. The RFID tag of claim 26, wherein the response enable module is configured to enable a response to the read signal if the measured duration of time is greater than a stored threshold time value.

28. The RFID tag of claim 27, further comprising:

a memory that stores the threshold time value.

29. The RFID tag of claim 14, further comprising:

a memory that stores a threshold signal strength value.