Article recognition and verification

• US 6,598,793 B1
• Filed: 06/30/1999
• Issued: 07/29/2003
• Est. Priority Date: 12/12/1996
• Status: Expired due to Fees

• Current Assignee: NV Bekaert SA
• Original Assignee: NV Bekaert SA
• Inventors: Fisher, John, Robertson, Paul, Burrell, Jon, Cross, David
• Primary Examiner(s): Lee, Diane I.
• Application Number:
  US09/308,566
• Time in Patent Office: 1,490 Days
• Field of Search: 235/449, 235/450, 235/472.01, 235/493, 902/7, 902/11, 324/605, 324/606, 324/609, 324/617, 324/642, 194/212, 194/213
• US Class Current: 235/449
• CPC Class Codes: G06K 7/084 sensing magnetic material by relative movement detecting flux changes without altering its magnetised state
• CPC Class Codes: G07D 7/04 Testing magnetic properties of the materials thereof, e.g. by detection of magnetic imprint G07D7/01 takes precedence
• CPC Class Codes: G07F 7/086 by passive credit-cards adapted therefor, e.g. constructive particularities to avoid counterfeiting, e.g. by inclusion of a physical or chemical security-layer for security documents G07D7/00; for the reading of record-carriers in general G06K7/00; for the design of coded credit-cards G06K19/10

Abstract

A method for checking the authenticity of a security article of the type containing magnetic particles having a magnetic saturation field H_s being greater than 100 A/m. The method includes the following steps: (a) generating an alternating field of one or more fundamental frequencies; (b) subjecting an article to be detected to the field; (c) detecting a detection signal emanating from the article to be detected; and (d) examining the detection signal for the presence of any particular higher harmonics of the fundamental frequencies or of any linear combination of the fundamental frequencies and of the harmonics, the particular harmonics or the linear combination being indicative of the presence of the magnetic particles. The method is applied at point of transaction locations, where the article to be detected is brought into close proximity with a sensor.

Claims

1. A method for checking the authenticity of a security article, said security article containing a plurality of randomly dispersed magnetic metal fibers, said method comprising the following steps:

(a) generating an alternating field of one or more fundamental frequencies with an amplitude being greater than the saturation field of the magnetic metal fibers of the security article;

(b) subjecting the security article to be detected to said field;

(c) detecting a detection signal emanating from said security article to be detected; and

(d) examining the detection signal for the presence of any particular harmonics of said fundamental frequency or said fundamental frequencies or of any linear combination of said fundamental frequencies and of said harmonics, said particular harmonics or said linear combination being indicative of the presence of the plurality of randomly dispersed magnetic metal fibers.

2. A method according to claim 1 wherein said magnetic metal fibers have a saturation field H_s of at least 100 A/m.

3. A method according to claim 2, wherein said magnetic saturation field is greater than 200 A/m.

4. A method according to claim 3, wherein said magnetic saturation field is greater than 300 A/m.

5. A method according to claim 1, wherein said alternating field is of sufficient strength to cause a substantial nonlinear response in flux density in the magnetic element or magnetic metal fibers to generate said harmonics.

6. A method according to claim 1, wherein the detection signal is constituted by electrical signals, said method further comprising the step of selectively processing said electrical signals at said particular harmonic frequencies in preference to signals at other frequencies, detecting for the presence of signals in the output of the said selective processing and generating an authentication signal in response to the said detection.

7. A method according to claim 1, wherein said generated alternating field has only one fundamental frequency.

8. A method according to claim 1, wherein said magnetic metal fibers have a demagnetisation factor smaller than {fraction (1/20)}.

9. A method according to claim 8, wherein said magnetic metal fibers have a demagnetisation factor N smaller than {fraction (1/250)}.

10. A method according to claim 1, wherein said alternating field is a local field operating in close proximity to the article to be detected.

11. A method according to claim 10, wherein said local field is generated by means of a sensor and wherein said sensor is brought into contact with said article to be detected or wherein said article to be detected is brought into contact with said sensor.

12. A method according to claim 11, wherein a relative movement is introduced between said sensor and said article to be detected, so that if perchance a region which is devoid of said magnetic metal fibers is in registry with the sensor, the movement will cause a region which does contain said magnetic metal fibers to be moved in registry with the sensor.

13. A method according to claim 12, wherein said movement involves a wiping action of said sensor with respect to said article to be detected or vice versa to enable different regions of the article to be detected by the sensor.

14. A method according to claim 11, wherein said method further comprises an initial step of activating said sensor so that checking of an article is restricted to when said sensor is activated.

15. A method according to claim 1, wherein said method comprises a step of producing an authentication signal in case magnetic metal fibers are detected in at least one region of said article to be detected.

16. A method according to claim 15, wherein a visual authentication signal is produced.

17. A method according to claim 16, wherein said method comprises the steps of:

a) causing a first lamp to operate when said sensor is activated and when no magnetic metal fibers are detected; and

b) causing a second lamp to operate when magnetic metal fibers are detected.

18. A method according to claim 15, wherein an audible authentication signal is produced.

19. A method according to claim 18, wherein said method comprises the steps of:

a) producing a first tone when said sensor is activated; and

b) producing a second tone in place of the first tone when magnetic metal fibers are detected.

20. A method according to claim 19, wherein said first tone and said second tone are at substantially different pitches.

21. A method according to claim 19, wherein said first tone and said second tone are at substantially different power levels.

22. A method according to any one of claim 19, wherein the first tone is produced for a set period of time before the second tone can be generated so that any user has to listen initially to the first tone.

23. A method according to any one of claim 15, wherein a vibratory authentication signal is produced.

24. A method according to claim 1, wherein said method comprises a step of producing an alarm signal in case no magnetic metal fibers are detected in said article to be detected.

25. A method according to claim 1, wherein said one or each said fundamental frequency lies above 1 kHz.

26. An apparatus adapted for carrying out a method for checking the authenticity of a security article according to claim 1, said security article containing at least one magnetic element, said apparatus comprising:

a) means for generating an alternating field of one or more fundamental frequencies with an amplitude being greater than the saturation field of the magnetic element;

b) means for detecting a detection signal emanating from said article to be detected; and

c) means for examining the detection signal for the presence of any particular harmonics of said fundamental frequency or said fundamental frequencies or any linear combination of said fundamental frequencies and of said harmonics, said particular harmonics or said linear combination being indicative of the presence of said magnetic element.

27. An apparatus according to claim 26, said apparatus comprising an inductor for generating said alternating field and for detecting said detection signal.

28. An apparatus according to claim 27, wherein said inductor comprises at least two separate windings, a first winding being associated with said alternating field and a second winding being associated with a field emanating from said article to be detected.

29. An apparatus according to claim 28, wherein said winding or windings are wound around a ferrite core.

30. An apparatus according to claim 29, wherein said ferrite core has an E-section.

31. An apparatus according to claim 29, wherein said ferrite core is a pot core.

32. An apparatus according to claim 27, wherein said inductor comprise a single winding being associated with both said alternating field and a field emanating from said article to be detected.

33. An apparatus according to claim 26, wherein said apparatus comprises a Hall effect device.

34. An apparatus according to claims 26, wherein said apparatus comprises a magneto-resistive device.

35. An apparatus according to claim 26, said apparatus comprising means for examining the detection signal, wherein said means comprises a narrow bandpass filter restricted to one, or to a group, of the harmonics of the source signal.

36. An apparatus according to claim 35, wherein said means for examining the detection signal comprises a surface acoustic wave filter.

37. An apparatus according to claim 26, wherein said means for examining the detection signal comprises a phase sensitive detector so as to produce maximum rejection of unwanted frequencies and maximum separation of desired harmonics.

38. An apparatus according to claim 26, wherein said apparatus further comprises means for producing an authentication signal.

39. An apparatus according to claim 26, wherein said apparatus further comprises a document screening device to which a document to be detected can be presented.

40. An apparatus according to claim 26, wherein a sensor comprises means for activating the apparatus so that the checking of an article is restricted to when the apparatus is activated.

41. An apparatus according to claim 40, wherein said means for activating the apparatus comprise a switch operable from open to closed condition if the apparatus is pressed into contact with the article to be detected or vice versa.

42. An apparatus according to claim 26, wherein the apparatus is part of a portable device suitable for being held in a hand.

43. A portable device according to claim 42, wherein said device is in the form of an elongate pen-like member.

44. A hand-held device according to claim 42, wherein said device is in the form of a thumb stall or finger stall.

45. An apparatus according to claim 26, said apparatus further comprising a platform on which the article to be detected can be placed.

46. An apparatus according to claim 45, further comprising means for moving said sensor relative to the platform to enable different regions of the article to be detected.

47. An apparatus according to claim 26, wherein the apparatus is a part of a cash register.

48. An apparatus according to claim 26, wherein the apparatus is a part of a computer terminal.

49. An apparatus according to claim 26, wherein the apparatus is a part of an automatic vending machine.

50. An apparatus according to claim 26, wherein the apparatus is a part of an automatic bank note counting machine.

51. An apparatus according to claim 26, wherein the apparatus is a part of a bank note checking machine.

52. A method of making a verifiable article which is to be detected by subjecting it to an alternating magnetic field to determine whether there is at least one specific harmonic response generated by interaction between the article and the field due to the non-linear response of the flux density with the applied field from randomly dispersed metal fibers of magnetic material associated with the article, said method comprising the step of selecting the magnetic material properties and the shape of the metal fibers so that they have a magnetic saturation field greater than 100 A/m so as to prevent triggering off electronic article surveillance (EAS) systems which also include magnetic fields, and incorporating said randomly dispersed metal fibers of magnetic material into the said article.

53. A method as in claim 52, wherein:

a) the step of selecting includes the selection of the said magnetic material and the selection of the said shape being restricted to metal fibers which require magnetic fields in excess of 300 A/m before they become saturated.

54. A system by which security articles can be verified, wherein authentic articles have incorporated therein randomly dispersed metal fibers of a selected magnetic material and of a selected shape, said randomly dispersed metal fibers being saturable by an alternating magnetic field thereby to generate at least one harmonic of a fundamental frequency of the alternating field;

and wherein a sensor is provided, a first part of which generates a local alternating magnetic field to which articles as aforesaid are to be subjected for verification, and a second part of which generates by induction electric signals indicative of the response of the material making up the article to the said alternating field;

a signal analysing device is provided, configured to determine if a particular harmonic or a spectrum of harmonics, is present in the generated signals;

the selection of the said magnetic material and the selection of the said shape is restricted to metal fibers which require magnetic fields in excess of 100 A/m before they become saturated, to prevent authentic articles as aforesaid from triggering electronic articles surveillance alarms, and the first part of the sensor generates a local field of sufficient strength to saturate any such metal fibers if in close proximity to, or in contact with, the sensor.

55. A system as in claim 54, wherein:

a) the selection of the said magnetic material and the selection of the said shape is restricted to metal fibers which require magnetic fields in excess of 300 A/m before they become saturated.