RFID material tracking method and apparatus

• US 20070296595A1
• Filed: 08/31/2007
• Published: 12/27/2007
• Est. Priority Date: 08/09/1999
• Status: Active Grant

• Current Assignee: Round Rock Research LLC
• Original Assignee: Micron Technology, Inc.
• Inventors: Moore, Scott
• Granted Patent: US 8,378,789 B2
• Time in Patent Office: Days
• US Class Current: 340/572.7
• 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 7/10336 the antenna being of the near field type, inductive coil
• CPC Class Codes: G08B 13/2462 Asset location systems combined with EAS inventory, tracking, logistic G06Q10/00; entrance control systems G07C9/00

Abstract

A method and apparatus for tracking items automatically is described. A passive RFID (Radio Frequency IDentification) tag is used with a material tracking system capable of real-time pinpoint location and identification of thousands of items in production and storage areas. Passive RFID tags are attached to the item to be tracked, remote sensing antennas are placed at each remote location to be monitored, interrogators with several antenna inputs are connected to the sensing antennas to multiplex the antenna signals, and a host computer communicates with the interrogators to determine item locations to an exacting measure.

Claims

1. A method of detecting the presence or absence of an identification tag at a location using a sensing antenna, comprising:

exciting a tuned tank circuit that includes the sensing antenna, the tuned tank circuit and the sensing antenna being separate from the identification tag, the tuned circuit and the sensing antenna separate from an interrogator that initiates the exciting of the tuned tank circuit; and

determining, in the interrogator, if a dipped pulse stream is present at the excited tank circuit.

2. The method of claim 1, wherein exciting a tuned tank circuit includes driving the tuned tank circuit with a square wave power signal.

3. The method of claim 2, wherein driving the tuned tank circuit with a square wave power signal includes operating the drive signal at about 125 kHz.

4. The method of claim 1, wherein exciting a tuned tank circuit includes driving the tuned tank circuit with a square wave power signal such that the tuned tank circuit smoothes the square wave signal to substantially a sine wave signal.

5. The method of claim 1, wherein exciting a tuned tank circuit includes providing a signal through a first inductor to a driver to the tuned tank circuit, the driver coupled to ground by a second inductor, wherein the first and second inductor are used to control the rise and fall times of the driver.

6. The method of claim 1, wherein determining if a dipped pulse stream is present at the excited tuned tank circuit includes detecting a signal appearing as a pulse stream in the form of a series of dips in a 125 kHz rectified carrier signal.

7. The method of claim 1, wherein determining if a dipped pulse stream is present at the excited tuned tank circuit includes detecting a signal from the identification tag with an antenna coil and rectifying the signal with a diode.

8. The method of claim 7, wherein rectifying the signal is followed by decoding the signal for extracting information related to the identification tag.

9. The method of claim 8, wherein extracting information related to the identification tag includes extracting a serial number.

10. A method of detecting the presence or absence of an identification tag, comprising:

exciting a tuned tank circuit that includes a sensing antenna, the tuned tank circuit and the sensing antenna being separate from the identification tag, the tuned circuit and the sensing antenna being separate from an interrogator that initiates the exciting of the tuned tank circuit;

detecting a signal from the identification tag in response to exciting the tuned tank circuit in the sensing antenna; and

decoding, in the interrogator, the detected signal to extract identification tag data carried in the detected signal.

11. The method of claim 10, wherein exciting a tuned tank circuit includes driving the tuned tank circuit with a square wave power signal.

12. The method of claim 10, wherein exciting a tuned tank circuit includes driving the tuned tank circuit with a square wave power signal such that the tuned tank circuit smoothes the square wave signal to substantially a sine wave signal.

13. The method of claim 10, wherein exciting a tuned tank circuit includes providing a signal through a first inductor to a driver to the tuned tank circuit, the driver coupled to ground by a second inductor, wherein the first and second inductor are used to control the rise and fall times of the driver.

17. A method of detecting the presence or absence of an identification tag, comprising:

exciting a tuned tank circuit that includes a sensing antenna, the tuned tank circuit and the sensing antenna being separate from the identification tag, the tuned circuit and the sensing antenna being separate from an interrogator that initiates the exciting of the tuned tank circuit;

decoding a detected signal in the interrogator, the detected signal responsive to exciting the tuned tank circuit and generated from the identification tag; and

storing information indicative of the presence or absence of the identification tag.

14. The method of claim 21, wherein detecting a signal from the identification tag in response to exciting the tuned tank circuit in the sensing antenna includes detecting a signal from the identification tag with an antenna coil and rectifying the signal with a diode.

15. The method of claim 21, wherein decoding the detected signal to extract identification tag data carried in the detected signal includes decoding data from a detector circuit using a processor for extracting identification tag data.

16. The method of claim 26, wherein decoding data from a detector circuit using a processor for extracting identification tag data includes extracting a serial number.

18. The method of claim 17, wherein exciting a tuned tank circuit includes driving the tuned tank circuit with a square wave power signal.

19. The method of claim 17, wherein exciting a tuned tank circuit includes providing a signal through a first inductor to a driver to the tuned tank circuit, the driver coupled to ground by a second inductor, wherein the first and second inductor are used to control the rise and fall times of the driver.

20. The method of claim 17, wherein decoding a detected signal includes decoding data from a detector circuit using a processor for extracting identification tag data.

21. The method of claim 17, wherein storing information indicative of the presence or absence of an identification tag includes storing the information in a database.

22. The method of claim 17, wherein storing information indicative of the presence or absence of an identification tag includes storing a serial number.

23. The method of claim 17, wherein storing information indicative of the presence or absence of an identification tag includes storing the information in a processor having on board memory.

24. The method of claim 17, wherein storing information indicative of the presence or absence of an identification tag includes storing the information in a processor for subsequent communication to a host computer.

25. The method of claim 24, wherein communicating the stored information to a host computer includes communicating the stored information wirelessly.

26. The method of claim 24, wherein communicating the stored information to a host computer includes communicating the stored information using an ETHERNET protocol.

27. The method of claim 17, wherein storing information indicative of the presence or absence of an identification tag includes forming historical information related to the identification tag.

28. A method of detecting the presence or absence of a plurality of identification tags, comprising:

for each identification tag of the plurality of identification tags,

associating a sensing antenna with the identification tag;

exciting a tuned tank circuit that includes the sensing antenna, the tuned tank circuit and the sensing antenna being separate from the identification tag, the tuned circuit and the sensing antenna being separate from an interrogator that initiates the exciting of the tuned tank circuit;

detecting a signal from the identification tag in response to exciting the tuned tank circuit that includes the sensing antenna; and

decoding in the interrogator, the detected signal from the identification tag to extract data carried in the detected signal, wherein detecting the presence or absence of each identification tag is performed sequentially.

29. The method of claim 28, wherein the method further includes, for each identification tag, removing the excitation from the tuned tank circuit in the sensing antenna prior to exciting a tuned circuit in a sensing antenna for another identification tag of the plurality of identification tags.

30. The method of claim 28, wherein exciting a tuned tank circuit includes driving the tuned tank circuit with a square wave power signal.

31. The method of claim 28, wherein exciting a tuned tank circuit includes providing a signal through a first inductor to a driver to the tuned tank circuit, the driver coupled to ground by a second inductor, wherein the first and second inductor are used to control the rise and fall times of the driver.

32. The method of claim 28, wherein detecting a signal from the identification tag in response to exciting the tuned tank circuit in the sensing antenna includes detecting a signal from the identification tag with an antenna coil and rectifying the signal with a diode.

33. The method of claim 28, wherein decoding the detected signal from the identification tag to extract data carried in the detected signal includes decoding data from a detector circuit using a processor for extracting identification tag data.

34. The method of claim 28, the method further including, for each identification tag, storing information indicative of the presence or absence of an identification tag.

35. The method of claim 34, wherein storing information indicative of the presence or absence of an identification tag includes storing the information in a database.

36. The method of claim 34, wherein storing information indicative of the presence or absence of an identification tag includes storing a serial number.

37. The method of claim 34, wherein storing information indicative of the presence or absence of an identification tag includes storing the information in a processor having on board memory.

38. The method of claim 34, wherein storing information indicative of the presence or absence of an identification tag includes storing the information in a processor for subsequent communication to a host computer.

39. The method of claim 34, wherein storing information indicative of the presence or absence of an identification tag includes forming historical information related to the identification tag.

40. A machine-readable medium having machine-executable instructions for performing a method of detecting the presence or absence of an identification tag, the method comprising:

exciting a tuned tank circuit that includes an antenna, the tuned tank circuit and the antenna being separate from the identification tag, the tuned circuit and the sensing antenna being separate from an interrogator that initiates the exciting of the tuned tank circuit; and

determining, in the interrogator, if a dipped pulse stream is present at the excited tuned tank circuit.

41. The machine-readable medium of claim 40, wherein exciting a tuned tank circuit includes driving the tuned tank circuit with a square wave power signal.

42. The machine-readable medium of claim 41, wherein driving the tuned tank circuit with a square wave power signal includes operating the drive signal at about 125 kHz.

43. The machine-readable medium of claim 40, wherein exciting a tuned tank circuit includes driving the tuned tank circuit with a square wave power signal such that the tuned circuit smoothes the square wave signal to substantially a sine wave signal.

44. The machine-readable medium of claim 40, wherein exciting a tuned tank circuit includes providing a signal through a first inductor to a driver to the tuned tank circuit, the driver coupled to ground by a second inductor, wherein the first and second inductor are used to control the rise and fall times of the driver.

45. The machine-readable medium of claim 40, wherein determining if a dipped pulse stream is present at the excited tuned tank circuit includes detecting a signal appearing as a pulse stream in the form of a series of dips in a 125 kHz rectified carrier signal.

46. The machine-readable medium of claim 40, wherein determining if a dipped pulse stream is present at the excited tuned tank circuit includes detecting a signal from the identification tag with an antenna and rectifying the signal with a diode.

47. The machine-readable medium of claim 46, wherein rectifying the signal is followed by decoding the signal for extracting information related to the identification tag.

48. The machine-readable medium of claim 47, wherein extracting information related to the identification tag includes extracting a serial number.

49. A machine-readable medium having machine-executable instructions for performing a method of detecting a presence or absence of a plurality of identification tags, the method comprising:

for each identification tag of the plurality of identification tags,

associating a sensing antenna with the identification tag;

exciting a tuned tank circuit that includes the sensing antenna, the tunned tank circuit and the sensing antenna being separate from the identification tag, the tuned circuit and the sensing antenna being separate from an interrogator that initiates the exciting of the tuned tank circuit;

detecting a signal from the identification tag in response to exciting the tuned tank circuit in the sensing antenna; and

decoding, in the interrogator, the detected signal from the identification tag to extract data carried in the detected signal.

50. The machine-readable medium of claim 49, wherein the machine-executable instructions include, for each identification tag, removing the excitation from the tuned tank circuit in the sensing antenna prior to exciting a tuned circuit in a sensing antenna for another identification tag of the plurality of identification tags.

51. The machine-readable medium of claim 49, wherein exciting a tuned tank circuit includes driving the tuned tank circuit with a square wave power signal.

52. The machine-readable medium of claim 49, wherein exciting a tuned tank circuit includes providing a signal through a first inductor to a driver to the tuned tank circuit, the driver coupled to ground by a second inductor, wherein the first and second inductor are used to control the rise and fall times of the driver.

53. The machine-readable medium of claim 49, wherein detecting a signal from the identification tag in response to exciting the tuned tank circuit in the sensing antenna includes detecting a signal from the identification tag with an antenna coil and rectifying the signal with a diode.

54. The machine-readable medium of claim 49, wherein decoding the detected signal from the identification tag to extract data carried in the detected signal includes decoding data from a detector circuit using a processor for extracting identification tag data.

55. The machine-readable medium of claim 49, wherein the machine-executable instructions include, for each identification tag, storing information indicative of the presence or absence of an identification tag.

56. The machine-readable medium of claim 55, wherein storing information indicative of the presence or absence of an identification tag includes storing the information in a database.

57. The machine-readable medium of claim 55, wherein storing information indicative of the presence or absence of an identification tag includes storing a serial number.

58. The machine-readable medium of claim 55, wherein storing information indicative of the presence or absence of an identification tag includes storing the information in a processor having on board memory.

59. The machine-readable medium of claim 55, wherein storing information indicative of the presence or absence of an identification tag includes storing the information in a processor for subsequent communication to a host computer.

60. The machine-readable medium of claim 55, wherein storing information indicative of the presence or absence of an identification tag includes forming historical information related to the identification tag.