Passive microwave tag identification system

• US 6,798,349 B1
• Filed: 10/04/1999
• Issued: 09/28/2004
• Est. Priority Date: 10/04/1999
• Status: Expired due to Fees

• Current Assignee: Chartoleaux KG LLC (Intellectual Ventures LLC)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Harrison, Beverly L., Richley, Edward A.
• Primary Examiner(s): TONG, NINA C
• Application Number:
  US09/411,268
• Time in Patent Office: 1,821 Days
• Field of Search: 340/10.41, 340/825.49, 340/225.36, 340/988, 340/990, 340/989, 340/995, 340/572.1, 340/572.5, 340/572.9, 340/572.8, 340/572.7, 342/25, 342/5, 342/6, 342/44, 342/42, 342/29, 342/30, 342/147, 342/118, 342/114, 342/61
• US Class Current: 340/539.13
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
• 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

Abstract

A system for identification and tracking of microwave responsive tags, the system comprising, a microwave responsive tag having a passive modulating element to uniquely backscatter directed microwave beams, a microwave base station for directing microwave beams in room sized areas, and a tag tracking system receiving input from the microwave base station, the tag tracking system storing state records of position and informational content of the microwave tag.

Claims

1. A system for identification and tracking of microwave responsive tags, the system comprising,

a microwave responsive tag having a passive modulating element to uniquely backscatter directed microwave beams,

a microwave base station for directing microwave beams in room sized areas, and

a tag tracking system receiving input from the microwave base station, the tag tracking system storing state records of position and informational content of the microwave tag, wherein the tag tracking system determines angular position of the microwave responsive tag with respect to the microwave base station.

2. The system of claim 1, wherein the microwave responsive tag is attached to a document.

3. The system of claim 1, wherein the microwave responsive tag is embedded in an object.

4. A system for identification and tracking of microwave responsive tags, the system comprising,

a microwave responsive tag having a passive modulating element to uniquely backscatter directed microwave beams and provide a signal,

a sensor circuit connected to the passive modulating elements, with state of the sensor circuit selectively modifying the signal,

a microwave base station for directing microwave beams in room sized areas, and

a tag tracking system receiving input from the microwave base station, the tag tracking system storing state records of position and informational content of the microwave tag, wherein the microwave base station generates a signal receivable by the sensor circuit to change sensor circuit state and selectively modifying the signal.

5. The system of claim 4, wherein the tag tracking system determines angular position of the microwave responsive tag with respect to the microwave base station.

6. The system of claim 4, further comprising at least two microwave base stations, and wherein the tag tracking system determines absolute position of the microwave responsive tag based on input from at least two microwave base stations.

7. The system of claim 4, wherein the microwave responsive tag further comprises a resonant circuit that amplitude modulates a backscattered directed microwave beam.

8. The system of claim 4, wherein the microwave responsive tag further comprises a Complimentary Metal Oxide Semiconductor circuit for varying voltage on a varactor diode connected to the stub to selectively amplitude modulate a backscattered directed microwave beam.

9. The system of claim 4, wherein the microwave responsive tag further comprises a resonant circuit that phase modulates a backscattered directed microwave beam.

10. The system of claim 4, wherein the microwave responsive tag further comprises a Complimentary Metal Oxide Semiconductor circuit for varying voltage on a varactor diode connected to the stub to selectively phase modulate a backscattered directed microwave beam.

11. The system of claim 4, wherein the microwave responsive tag is attached to a document.

12. The system of claim 4, wherein the microwave responsive tag is embedded in an object.

13. A system for identification and tracking of microwave responsive tags, the system comprising,

a microwave responsive tag having a passive modulating element to uniquely backscatter directed microwave beams,

a microwave base station for directing microwave beams in room sized areas,

a tag tracking system receiving input from the microwave base station, the tag tracking system storing state records of position and informational content of the microwave tag, and

at least two microwave base stations, and wherein the tag tracking system determines absolute position of the microwave responsive tag based on input from at least two microwave base stations.

14. The system of claim 13, wherein the microwave responsive tag is attached to a document.

15. The system of claim 13, wherein the microwave responsive tag is embedded in an object.

16. A system for identification and tracking of microwave responsive tags, the system comprising,

a microwave responsive tag having a passive modulating element to uniquely backscatter directed microwave beams,

a microwave base station for directing microwave beams in room sized areas, and

a tag tracking system receiving input from the microwave base station, the tag tracking system storing state records of position and informational content of the microwave tag, wherein the microwave responsive tag further comprises a resonant circuit that amplitude modulates a backscattered directed microwave beam.

17. A system for identification and tracking of microwave responsive tags, the system comprising,

a microwave responsive tag having a passive modulating element to uniquely backscatter directed microwave beams,

a microwave base station for directing microwave beams in room sized areas, and

a tag tracking system receiving input from the microwave base station, the tag tracking system storing state records of position and informational content of the microwave tag, wherein the microwave responsive tag further comprises a Complimentary Metal Oxide Semiconductor circuit for varying voltage on a varactor diode connected to the stub to selectively amplitude modulate a backscattered directed microwave beam.

18. A system for identification and tracking of microwave responsive tags, the system comprising,

a microwave responsive tag having a passive modulating element to uniquely backscatter directed microwave beams,

a microwave base station for directing microwave beams in room sized areas, and

a tag tracking system receiving input from the microwave base station, the tag tracking system storing state records of position and informational content of the microwave tag, wherein the microwave responsive tag further comprises a resonant circuit that phase modulates a backscattered directed microwave beam.

19. A system for identification and tracking of microwave responsive tags, the system comprising,

a microwave responsive tag having a passive modulating element to uniquely backscatter directed microwave beams,

a microwave base station for directing microwave beams in room sized areas, and

a tag tracking system receiving input from the microwave base station, the tag tracking system storing state records of position and informational content of the microwave tag, wherein the microwave responsive tag further comprises a Complimentary Metal Oxide Semiconductor circuit for varying voltage on a varactor diode connected to the stub to selectively phase modulate a backscattered directed microwave beam.

20. A system for identification and tracking of microwave responsive tags, the system comprising,

a microwave responsive tag having a passive modulating element to uniquely backscatter directed microwave beams,

a microwave base station for directing microwave beams in room sized areas, and

a tag tracking system receiving input from the microwave base station, the tag tracking system storing state records of position and informational content of the microwave tag, wherein the tag tracking system can generate a series of time dependent snapshots of position of microwave responsive tags and any associated informational content.