Radio frequency automatic identification system

• US 5,581,257 A
• Filed: 08/30/1994
• Issued: 12/03/1996
• Est. Priority Date: 09/24/1991
• Status: Expired due to Fees

• Current Assignee: Gordian Holding Corporation
• Original Assignee: Gordian Holding Corporation
• Inventors: Hurley, G. William, Greene, Morton
• Primary Examiner(s): PITTS, HAROLD I
• Application Number:
  US08/298,070
• Time in Patent Office: 826 Days
• Field of Search: 342/27, 342/51, 342/44, 235/375
• US Class Current: 342/51
• CPC Class Codes: C30B 29/18 Quartz
• CPC Class Codes: C30B 33/00 After-treatment of single crystals or homogeneous polycrystalline material with defined structure C30B31/00 takes precedence
• CPC Class Codes: G01S 13/753 using frequency selective elements, e.g. resonator
• CPC Class Codes: G06K 19/0672 with resonating marks
• CPC Class Codes: G06K 19/07 with integrated circuit chips
• 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
• CPC Class Codes: G06K 7/10009 sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves
• CPC Class Codes: G08B 13/2414 using inductive tags
• CPC Class Codes: G08B 13/2417 having a radio frequency identification chip
• CPC Class Codes: G08B 13/2422 using acoustic or microwave tags
• CPC Class Codes: G08B 13/244 Tag manufacturing, e.g. continuous manufacturing processes
• CPC Class Codes: G08B 13/2442 Tag materials and material properties thereof, e.g. magnetic material details
• CPC Class Codes: G08B 13/2445 Tag integrated into item to be protected, e.g. source tagging
• CPC Class Codes: G08B 13/2471 Antenna signal processing by receiver or emitter
• CPC Class Codes: G08B 13/2482 EAS methods, e.g. description of flow chart of the detection procedure

Abstract

A radio frequency automatic identification system detects targets which include a plurality of radio frequency resonators. Information is attributed to the target in accordance with the radio frequency response characteristics of the target, such as the resonant frequencies of resonators present, and/or the spatial locations within the target of the resonators. Preferred resonators include thin dipoles, which may be metallizations on a plastic film substrate. Information may be attributed to a target by fabricating the target with resonators disposed at locations to encode information in accordance with a predetermined encoding system; alternatively, resonators may be randomly disposed, and a translation code applied to convert the radio frequency information to particular information in a particular format. Readers for use in the system read the radio frequency response characteristics of a target in the near field of a radiating aperture which is illuminated by a radio frequency source. Items which may be encoded with radio frequency readable information include documents, credit cards, and computer diskettes.

Claims

1. A target for authenticating a document, comprising:

a plurality of thin dipoles disposed in a fixed arrangement on a substrate, each of said thin dipoles being formed of an elongated metal article having a random spatial position on said substrate, wherein said fixed arrangement of thin dipoles generates a composite RF waveform associated with said document when said plurality of thin dipoles are illuminated with RF energy.

2. The target of claim 1, wherein said plurality of thin dipoles are randomly disposed in said fixed arrangement on said substrate.

3. The target of claim 2, wherein each of said thin dipoles has a random angular orientation on said substrate.

4. The target of claim 1, wherein said fixed arrangement corresponds to an ordered arrangement of said plurality of thin dipoles on said substrate.

5. The target of claim 4, wherein each of said thin dipoles has an ordered angular orientation on said substrate.

6. The target of claim 1, wherein said thin dipoles are formed of metalized fibers.

7. The target of claim 6, wherein said thin dipoles are formed of metalized glass fibers.

8. The target of claim 1, wherein said thin dipoles are formed of aluminum.

9. The target of claim 1, wherein each of said thin dipoles is resonant at an interrogating frequency having a 1/2 wavelength equal to a length of said thin dipoles.

10. The target of claim 1, wherein said substrate is non-conductive.

11. The target of claim 10, wherein said substrate is selected from the group consisting of paper or plastic.

12. The target of claim 11, wherein said thin dipoles are disposed between inner and outer layers of plastic.

13. The target of claim 12, wherein said inner and outer layers of plastic represent first and second layers of an identification card.

14. The target of claim 13, wherein said identification card is a credit card.

15. The target of claim 1, wherein said substrate has a surface area and said plurality of thin dipoles are disposed throughout all of said surface area.

16. The target of claim 1, wherein said substrate has a surface area and said plurality of thin dipoles occupy only a portion of said surface area.

17. The target of claim 1, wherein said plurality of thin dipoles do not overlap on said substrate.

18. The target of claim 1, wherein said plurality of thin dipoles partially overlap on said substrate.

19. A method for forming a target for use in authenticating a document, comprising the step of disposing a plurality of thin dipoles in a fixed arrangement on a substrate, each of said thin dipoles being formed of an elongated metal article having a fixed spatial position on said substrate, wherein said fixed arrangement of thin dipoles generates a composite RF waveform associated with said document when said plurality of thin dipoles are illuminated with RF energy.

20. The method of claim 19, wherein said disposing step comprises the steps of:

(1) coating said substrate with a layer of metal to form a coated substrate;

(2) forming a plurality of exposed metal areas by applying a photo-resist layer to said coated substrate; and

(3) forming said plurality of thin dipoles by removing said exposed metal areas from said substrate with a chemical etchant.

21. The method of claim 19, wherein said plurality of thin dipoles are randomly disposed in said fixed arrangement on said substrate.

22. The method of claim 21, wherein each of said thin dipoles is disposed at a random angular orientation on said substrate.

23. The method of claim 19, wherein said fixed arrangement corresponds to an ordered arrangement of said plurality of thin dipoles on said substrate.

24. The method of claim 23, wherein each of said thin dipoles has an ordered angular orientation on said substrate.

25. The method of claim 19, wherein said thin dipoles are formed of metalized fibers.

26. The method of claim 19, wherein each of said thin dipoles is resonant at an interrogating frequency having a 1/2 wavelength equal to a length of said thin dipoles.

27. The method of claim 19, wherein said substrate is non-conductive.

28. The method of claim 19, wherein said substrate is selected from the group consisting of paper or plastic.

29. The method of claim 28, wherein said thin dipoles are disposed between inner and outer layers of plastic.

30. The method of claim 29, wherein said inner and outer layers of plastic represent first and second layers of an identification card.

31. The method of claim 30, wherein said identification card is a credit card.

32. The method of claim 19, wherein said substrate has a surface area and said plurality of thin dipoles are disposed throughout all of said surface area.

33. The method of claim 19, wherein said substrate has a surface area and said plurality of thin dipoles occupy only a portion of said surface area.

34. The method of claim 19, wherein said plurality of thin dipoles do not overlap on said substrate.

35. The method of claim 19, wherein said plurality of thin dipoles partially overlap on said substrate.

36. A system for authenticating an object, comprising:

(A) an RF source for illuminating said object with an RF source signal;

(B) an RF detector for receiving a composite RF response signal from said object in response to said RF source signal; and

(C) a processor, coupled to said detector, for determining whether said composite RF response signal is representative of an authentic response signal;

wherein a plurality of thin dipoles are disposed in a fixed arrangement on said object, each of said thin dipoles being formed of an elongated metal article having a fixed spatial position on said object, wherein said fixed arrangement of thin dipoles generates said composite RF response signal when said plurality of thin dipoles are illuminated with said RF source signal.

37. The system of claim 36, wherein said plurality of thin dipoles are randomly disposed in said fixed arrangement.

38. The system of claim 37, wherein each of said thin dipoles has a random angular orientation.

39. The system of claim 36, wherein said fixed arrangement corresponds to an ordered arrangement of said plurality of thin dipoles.

40. The system of claim 39, wherein each of said thin dipoles has an ordered angular orientation.

41. The system of claim 36, wherein said thin dipoles are formed of metalized fibers.

42. The system of claim 36, wherein said thin dipoles are formed of aluminum.

43. The system of claim 36, wherein each of said thin dipoles is resonant at an interrogating frequency having a 1/2 wavelength equal to a length of said thin dipoles.

44. The system of claim 36, wherein said plurality of thin dipoles are positioned on a substrate on said object.

45. The system of claim 44, wherein said substrate is non-conductive.

46. The system of claim 45, wherein said substrate is selected from the group consisting of paper or plastic.

47. The system of claim 46, wherein said thin dipoles are disposed between inner and outer layers of plastic.

48. The system of claim 47, wherein said inner and outer layers of plastic represent first and second layers of an identification card.

49. The system of claim 48, wherein said identification card is a credit card.

50. The system of claim 44, wherein said substrate has a surface area and said plurality of thin dipoles are disposed throughout all of said surface area.

51. The system of claim 44, wherein said substrate has a surface area and said plurality of thin dipoles occupy only a portion of said surface area.

52. The system of claim 44, wherein said plurality of thin dipoles do not overlap on said substrate.

53. The system of claim 44, wherein said plurality of thin dipoles partially-overlap on said substrate.

54. A method for authenticating an object, comprising the steps of:

(A) illuminating said object with an RF source signal from an RF source;

(B) receiving, with an RF detector, a composite RF response signal from said object in response to said RF source signal; and

(C) determining whether said composite RF response signal is representative of an authentic response signal;

wherein a plurality of thin dipoles are disposed in a fixed arrangement on said object, each of said thin dipoles being formed of an elongated metal article having a fixed spatial position on said object, wherein said fixed arrangement of thin dipoles generates said composite RF response signal when said plurality of thin dipoles are illuminated with said RF source signal.

55. The method of claim 54, further comprising the step of moving said object through a reading slot while illuminating said object with said RF source signal.

56. The method of claim 55, wherein said composite RF response signal represents an amplitude of an RF signal generated by said thin dipoles as said object is moved through said reading slot.

57. The method of claim 54, wherein said plurality of thin dipoles are randomly disposed in said fixed arrangement.

58. The method of claim 57, wherein each of said thin dipoles has a random angular orientation.

59. The method of claim 54, wherein said fixed arrangement corresponds to an ordered arrangement of said plurality of thin dipoles.

60. The method of claim 59, wherein each of said thin dipoles has an ordered angular orientation.

61. The method of claim 54, wherein each of said thin dipoles is resonant at an interrogating frequency having a 1/2 wavelength equal to a length of said thin dipoles.

62. The method of claim 54, wherein said plurality of thin dipoles are positioned on a substrate on said object.

63. The method of claim 62, wherein said substrate is non-conductive.

64. The method of claim 63, wherein said substrate is selected from the group consisting of paper or plastic.

65. The method of claim 64, wherein said thin dipoles are disposed between inner and outer layers of plastic.

66. The method of claim 65, wherein said inner and outer layers of plastic represent first and second layers of an identification card.

67. The method of claim 66, wherein said identification card is a credit card.

68. The method of claim 62, wherein said substrate has a surface area and said plurality of thin dipoles are disposed throughout all of said surface area.

69. The method of claim 62, wherein said substrate has a surface area and said plurality of thin dipoles occupy only a portion of said surface area.

70. The method of claim 62, wherein said plurality of thin dipoles do not overlap on said substrate.

71. The method of claim 62, wherein said plurality of thin dipoles partially-overlap on said substrate.