Radio frequency identification (RFID) tag location systems and methods

• US 20080100439A1
• Filed: 10/31/2006
• Published: 05/01/2008
• Est. Priority Date: 10/31/2006
• Status: Active Grant

• Current Assignee: Symbol Technologies, LLC (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: Rinkes, Charles
• Granted Patent: US 8,519,823 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 7/10079 the collision being resolved in the spatial domain, e.g. temporary shields for blindfolding the interrogator in specific directions
• CPC Class Codes: G06K 7/10217 parameter settings controlling the transmission power of the interrogator

Abstract

Methods, systems, and apparatuses for ways of locating tags are described. A power level of a RFID communication signal transmitted by a RFID device, such as a reader, is adjusted to hone in on a specific tag. For example, the power level may be decreased or increased, depending on the situation, to hone in on the tag. The RFID device may be repositioned to aid in further honing in on the tag. Transmitting RFID communication signals, adjusting transmit power levels, and repositioning the RFID device may be iterated as needed to hone in on the tag.

Claims

1. A method for locating a radio frequency identification (RFID) tag, comprising:

transmitting at least one communication signal from a transmitter at a selected transmit power level to determine a group of one or more tags present within a region and a read rate of a desired RFID tag, the group including the desired RFID tag; and

performing one or more of the following steps at least once to hone in on a physical location of the desired RFID tag;

adjusting the transmit power level based at least in part on a number of tags present in the determined group and the read rate,

transmitting a subsequent at least one communication signal from the transmitter at the adjusted transmit power level to determine a subsequent group of one or more tags present within a subsequent region and a subsequent read rate of the desired RFID tag, and

repositioning the transmitter.

2. A method for locating a radio frequency identification (RFID) tag, comprising:

selecting a first transmit power level;

transmitting a first at least one communication signal from a transmitter at the first transmit power level to determine a first group of one or more tags present within a first region and a read rate of a desired RFID tag; and

adjusting the first transmit power level to a second transmit power level based on a number of tags present in the first group and on the read rate of the desired RFID tag.

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

selecting the second transmit power level to be less than the first transmit power level if the first group includes the desired RFID tag.

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

selecting the second transmit power level to be greater than the first transmit power level if the first group does not include the desired RFID tag.

5. The method of claim 2, further comprising:

transmitting a second at least one communication signal from the transmitter at the second transmit power level to determine a second group of one or more tags present within a second region and a second read rate of the desired RFID tag; and

adjusting the second transmit power level to a third transmit power level based on a number of tags present in the second group and on the second read rate of the desired RFID tag.

6. The method of claim 2, further comprising:

iterating at least one of the transmitting step and the adjusting step at least once to hone in on a physical location of the desired RFID tag.

7. The method of claim 2, wherein said transmitting step comprises:

transmitting the first at least one communication signal from the transmitter at a first location.

8. The method of claim 7, further comprising:

repositioning the transmitter from the first location to a second location; and

transmitting a second at least one communication signal from the transmitter at the second location and at the second transmit power level to determine a second group of one or more tags present within a second region and a second read rate of the desired RFID tag.

9. The method of claim 8, further comprising:

selecting the second location to be within the first region if the first group includes the desired RFID tag.

10. The method of claim 8, further comprising:

selecting the second location to be outside of the first region if the first group does not include the desired RFID tag.

11. The method of claim 2, further comprising:

repositioning the transmitter from a first location to a second location; and

iterating at least one of the transmitting step, the adjusting step, and the repositioning step at least once to hone in on a physical location of the desired RFID tag.

12. The method of claim 2, further comprising:

enabling a user to interact with a user interface associated with the transmitter to perform said adjusting of the first transmit power level.

13. A method for locating a radio frequency identification (RFID) tag, comprising:

transmitting a first at least one communication signal from a transmitter at a first location to determine a first group of one or more tags present within a first region and a read rate of a desired RFID tag;

selecting a second location to be located within the first region if the first group includes the desired RFID tag or to be located outside of the first region if the first group does not include the desired RFID tag;

repositioning the transmitter from the first location to a second location; and

transmitting a second at least one communication signal from the transmitter at the second location to determine a second group of one or more tags present within a second region.

14. The method of claim 13, wherein said transmitting the first at least one communication signal comprises:

transmitting the first at least one communication signal at a first transmit power level; and

wherein said transmitting the second at least one communication signal comprises;

transmitting the second at least one communication signal at a second transmit power level.

15. The method of claim 14, further comprising:

selecting the second transmit power level to be less than the first transmit power level if the first group includes the desired RFID tag.

16. The method of claim 14, further comprising:

selecting the second transmit power level to be greater than the first transmit power level if the first group does not include the desired RFID tag.

17. The method of claim 13, further comprising:

performing one or more of the following steps at least once to hone in on a physical location of the desired RFID tag;

repositioning the transmitter to a subsequent location, and

transmitting a subsequent at least one communication signal from the transmitter at the subsequent location to determine a subsequent group of one or more tags present within a subsequent region and a subsequent read rate of the desired RFID tag.

18. A radio frequency identification (RFID) communications device, comprising:

an antenna;

a radio frequency identification (RFID) module coupled to the antenna, wherein the RFID module is configured to generate at least one communication signal that is transmitted by the antenna at a transmit power level, and the RFID module is configured to demodulate at least one tag response signal received by the antenna in response to the at least one communication signal to determine a group of one or more tags present within a region and a read rate of a desired RFID tag; and

a power ranging module configured to adjust the transmit power level of the communication signal to enable an operator of the RFID communications device to hone in on a physical location of the desired RFID tag.

19. The RFID communications device of claim 18, wherein the RFID communications device is mobile, thereby enabling an operator of the RFID communications device to reposition the RFID communications device to hone in on the physical location of the desired RFID tag.

20. The RFID communications device of claim 18, further comprising:

a user interface configured to enable an operator to interact with the power ranging module to adjust the transmit power level.

21. The RFID communications device of claim 18, wherein the RFID communications device is a RFID reader.

22. The RFID communications device of claim 18, wherein the RFID communications device is an RFID module that is attachable as an accessory to a handheld device.

23. The RFID communications device of claim 18, wherein transmit power level is decreased if a first at least one tag response signal received by the antenna determines that the desired RFID tag is present within the region.

24. The RFID communications device of claim 18, wherein transmit power level is increased if a first at least one tag response signal received by the antenna determines that the desired RFID tag is not present within the region.

25. A system for locating a radio frequency identification (RFID) tag, comprising:

means for transmitting at least one communication signal from a transmitter at a selected transmit power level to determine a group of one or more tags present within a region and a read rate of a desired RFID tag, the group including the desired RFID tag;

means for adjusting the transmit power level based at least in part on a number of tags present in the determined group and the read rate of the desired RFID tag; and

means for iterating at least one of the means for transmitting and the means for adjusting at least once to hone in on a physical location of the desired RFID tag.

26. The system of claim 25, further comprising:

enabling means for repositioning the transmitter.