Item finding using RF signalling

• US 20050285742A1
• Filed: 06/29/2004
• Published: 12/29/2005
• Est. Priority Date: 06/29/2004
• Status: Active Grant

• Current Assignee: Symbol Technologies, LLC (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: Bridgelall, Raj, Charych, Hal, Malik, Sumita, O'Haire, Michael
• Granted Patent: US 7,142,120 B2
• Time in Patent Office: Days
• US Class Current: 340/572.1
• CPC Class Codes: G01S 13/751 wherein the responder or reflector radiates a coded signal
• CPC Class Codes: G01S 3/20 derived by sampling signal received by an antenna system having periodically-varied orientation of directivity characteristic
• CPC Class Codes: G06K 17/00 Methods or arrangements for effecting co-operative working between equipments covered by two or more of main groups G06K1/00 - G06K15/00, e.g. automatic card files incorporating conveying and reading operations
• 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

Abstract

Methods and apparatus are provided for locating one among many items equipped with RFID tags. The apparatus comprises a portable system interrogating the RFID tags and receiving responses therefrom that depend at least on their bearing angle. A comparator selects responses from the one item and ignores others. An annunciator indicates the presence of the one item in the interrogator field of view and, desirably but not essentially, its relative proximity. A directional antenna whose beam pattern is limited in azimuth and/or elevation provides bearing angle information. Its field of view becomes progressively smaller as the antenna approaches the one item so that a user can substantially pinpoint its location without needing any of the usual RFID infrastructure. Tag response hit rate and/or signal strength provides range related information to the interrogator. Optionally, the presence of each new tag is announced until all new tags have been identified.

Claims

1. An item locating system comprising:

a portable communication system for interrogating an initially unknown item and receiving responses therefrom that depend upon the angle of bearing of the initially unknown item;

a comparator coupled to the communication system for comparing the received responses with a unique identifier for the item desired to be located; and

an annunciator coupled to the communication system and the comparator for indicating whether the communication system is directed along the angle of bearing.

2. The locating system of claim 1 further comprising a directional antenna coupled to the communication system for interrogating the item, wherein a spatially limited beam pattern of the antenna provides an indication of the angle of bearing of the particular item.

3. The locating system of claim 2 wherein the annunciator provides audible signals whose repetition rate depends upon the proximity of the item.

4. The locating system of claim 3 wherein the repetition rate of the audible signals increases as the directional antenna approaches the item.

5. The locating system of claim 3 wherein the repetition rate of the audible signals increases as the directional antenna points toward the item and decreases as the directional antenna points in other directions.

6. The locating system of claim 2 wherein output of the annunciator increases as the directional antenna points toward the item and decreases as the directional antenna points in other directions.

7. The locating system of claim 2 wherein the directional antenna has a principal lobe in a direction toward the item to be located.

8. The location system of claim 7 wherein the principal antenna lobe is limited in both azimuth and elevation.

9. The locating system of claim 1 wherein the item provides responses in the form of RF signaling packets comprising an identifier unique to the item.

10. The locating system of claim 9 wherein the annunciator gives an indication of the time rate of receipt of the RF signaling packets.

11. A system for locating an item having an RFID tag with a unique identifier, comprising:

an annunciator for providing item location information to a system user;

a data input for entering the unique identifier;

a memory coupled to the data input for storing the unique identifier;

one or more antennas for transmitting interrogation signals to the RFID tag and receiving responses from the RFID tag, wherein at least one of the one or more antennas is directional so as to have a field of view that is spatially limited in azimuth or elevation and range;

an RFID tag interrogator coupled to the one or more antennas, wherein the interrogator is adapted to transmit an RFID tag interrogation signal to and receive a response from the RFID tag by means of the one or more antennas, wherein the response includes an identifier for the RFID tag providing the response;

a processor coupled to the annunciator, the data input;

the memory and the interrogator, wherein the processor compares the RFID tag identifier received by the interrogator to the unique identifier stored in the memory and if they match, causes the annunciator to emit a user alert signal dependant on the proximity to the interrogator of the RFID tag providing the matching response.

12. The system of claim 111 further adapted to receive an on-board power source so that the system is portable.

13. The system of claim 111 wherein the interrogator provides a range related signal to the processor, the range related signal depending on the signal strength or repetition rate or both of the responses received from the RFID tag, and wherein the user alert emitted by the annunciator is derived by the processor from such range related signal.

14. A method of locating a particular item from among a plurality of items, using an RFID tag interrogator, wherein each item has thereon an RFID tag containing a unique identifier, comprising:

obtaining and storing the unique identifier for the particular item desired to be located;

interrogating the tags of the plurality of items to determine their unique identifiers;

comparing the unique identifiers obtained from the multiplicity of items to the stored unique identifier for the particular item desired to be located and, if there is a match;

presenting to a user relative position dependant data for the tag having the unique identifier for the particular item desired to be located; and

repeating the interrogating, comparing steps and presenting steps for different locations of the interrogator, thereby obtaining position dependant data pointing to the particular item.

15. The method of claim 14 wherein the position dependant data has a repetition rate or intensity or both that increases as the distance between the particular item and interrogator decreases.

16. The method of claim 14 wherein the interrogating step comprises interrogating those of the plurality of items that are within an RF field of view of the interrogator.

17. The method of claim 14 wherein the interrogating step comprises interrogating the plurality of items using a directional antenna.

18. The method of claim 15 wherein the repeating step comprises moving the interrogator in a direction corresponding to increases in repetition rate or intensity of the position dependant data.

19. The method of claim 14 further comprising:

prior to the interrogating step, setting an annunciator to provide an alert output the first time a response is received from a tag being interrogated; and

if there is no match in the comparing step, then shutting off the annunciator.

20. The method of claim 19 further comprising after the setting step, if there is a match in the comparing step, switching the annunciator to the presenting step.

21. A method by which a user can identify items containing RFID tags using a tag interrogator, comprising:

interrogating the RFID tags in the field of view of the interrogator;

obtaining the ID#s associated with the read tags;

determining whether new ID#s have been obtained and if so;

providing an announcement to the user for each new ID#, and

repeating the interrogating, obtaining, determining and providing steps until no new ID#s are obtained.

22. The method of claim 21 further comprising wirelessly transmitting the ID#s obtained to a system base station.

23. The method of claim 21 wherein the providing step comprises providing an audible announcement to the user substantially only for each new tag ID# obtained, said audible announcement ceasing when no further new tags ID#s are obtained.

24. The method of claim 21 further comprising after the repeating step:

determining whether the unique ID# of an item desired to be located has been entered by the user, and if so;

presenting range and bearing information concerning the item desired to be found to the user.

25. The method of claim 24 wherein, when the outcome of the step of determining whether the unique ID# has been entered is NO (FALSE), proceeding to END.