Electro-optic reader for retro-reflective bar codes

• US 20040211837A1
• Filed: 02/17/2004
• Published: 10/28/2004
• Est. Priority Date: 08/16/2001
• Status: Active Grant

• Current Assignee: Optidtech Optical Identification Technologies
• Original Assignee: Optidtech Optical Identification Technologies
• Inventors: Eisenberg, Naftali P, Drori, Avishai H
• Granted Patent: US 7,273,176 B2
• Time in Patent Office: Days
• US Class Current: 235/462.41
• CPC Class Codes: G02B 5/124 plural reflecting elements forming part of a unitary plate or sheet
• CPC Class Codes: G06K 19/06009 with optically detectable marking G06K19/063, G06K19/08 take precedence
• CPC Class Codes: G06K 2019/0629 Holographic, diffractive or retroreflective recording
• CPC Class Codes: G08G 1/017 identifying vehicles G08G1/015, G08G1/054 take precedence
• CPC Class Codes: G08G 1/04 using optical or ultrasonic detectors

Abstract

A system for identification comprising: a surface (14) comprising retro-reflective indicta; a source of light that illuminates the indicta (18) along an illumination direction; and a detector (20, 21) that views light reflected from the indicta, wherein the retro-reflector reflects the light that illuminates it as a plurality of beams at a plurality of angles relative to the illumination direction.

Claims

1. A system for identification comprising:

a surface comprising retro-reflective indicta;

a source of light that illuminates the indicta along an illumination direction; and

a detector that views light reflected from the indicta,

wherein the retro-reflector reflects the light that illuminates it as a plurality of beams at a plurality of angles relative to the illumination direction.

3. A system according to claim 1 wherein the plurality of beams lie on the surface of a circular or elliptical cone.

5. A system according to claim 1 wherein the plurality of beams provide a substantially continuous ring of reflected light.

6. A system according to claim 5 wherein the ring of light has substantially of the same intensity along its length.

7. A system according to claim 1 wherein the source and detector illuminate and view the surface at angles having a difference substantially equal to at least one of the multiple reflection angles.

9. A system according to claim 1 wherein the plurality of beams define the surface of two or more cones.

15. A system according to claim 7, wherein the detector is an imaging detector, that forms an image of the light retro-reflected from the surface.

17. A system according to claim 15 wherein the source of light does not scan the surface.

18. A system according to claim 15, wherein the imaging detector images a field of view that has an area at least 5 times as large as the area of the surface.

19. A system according to claim 18 wherein the imaging detector images a field of view that has an area at least 20 times as large as the area of the surface.

21. A system according to claim 19 wherein the imaging detector images a field of view that has an area at least 100 times as large as the area of the surface.

22. A system according to claim 15 and including an image processor that detects the presence of the surface in an image acquired by the imaging detector, wherein the retro-reflecting surface reflects light that forms an information carrying image and wherein the image processing circuitry is operative to extract the information from the image.

24. A system according to claim 22 wherein the information comprises a bar code.

25. A system according to claim 22 wherein the information comprises a two dimensional code.

26. A system according to claim 22 wherein the information comprises spectral information.

27. A system according to claim 1 wherein the source of light illuminates the surface with incoherent light.

28. A system according to claim 1, wherein the source and detector illuminate and view the surface at substantially the same angle.

29. A system according to claim 28, wherein the detector is an imaging detector.

30. A system according to claim 29 wherein the image on the imaging detector comprises a pattern corresponding to the angles at which the light is reflected.

31. A system according to claim 28 and including authentication circuitry which authenticates the surface when the detector detects a predetermined pattern of light.

32. A system according to claim 28 and including a reflector that reflects the light reflected by the retro-reflector so that it can be viewed outside the path of illumination.

34. A system according to claim 33claim 32 wherein the detector is situated at the plane of the source or at a virtual plane of the source or at an image of said source plane or virtual source plane.

36. A system according to claim 28 wherein the light source is a laser.

37. A system according to claim 36 wherein the detector views the light reflected by the retro-reflector without any focusing of the reflected light.

79. A system according to claim 9, wherein the detector is an imaging detector, that forms an image of the light retro-reflected from the surface.

80. A system according to claim 79 wherein the source of light does not scan the surface.

81. A system according to claim 79, wherein the imaging detector images a field of view that has an area at least 5 times as large as the area of the surface.

82. A system according to claim 79 wherein the imaging detector images a field of view that has an area at least 100 times as large as the area of the surface.

83. A system according to claim 79 and including an image processor that detects the presence of the surface in an image acquired by the imaging detector, wherein the retro-reflecting surface reflects light that forms an information carrying image and wherein the image processing circuitry is operative to extract the information from the image.

2. (Canceled)

4. (Canceled)

8. (Canceled)

10-14. -14. (Canceled)

16. (Canceled)

20. (Canceled)

23. (Canceled)

33. (Canceled)

35. (Canceled)

38. A system according to claim 35 or claim 36 and including a focusing element, having a focal length, that receives the light reflected by the retro-reflector, wherein the detector is placed in the path of the thus reflected beam, spaced from the focusing element by a distance other than the focal length.

39-43. -43. (Canceled)

44. A retro-reflective surface having information encoded thereon by having different areas thereof retro-reflecting with different retro-reflective intensities, to form indicta carrying the information, wherein the retro-reflector reflects the light that illuminates it as a plurality of beams at a plurality of angles to the illumination direction.

45. A surface according to claim 44 wherein the plurality of beams lie on the surface of a circular or elliptical cone.

47. A surface according to claim 44 wherein the plurality of beams provide a substantially continuous ring of reflected light when illuminated by a beam of light.

53. A surface according to claim 44 wherein the information is comprised in a two-dimensional code.

54. A surface according to claim 44 wherein the information is comprised in a bar code.

55. A surface according to claim 54 wherein the bar code is a stacked one-dimensional type code.

62. A surface according to claim 44 wherein the plurality of beams define the surface of two or more circular or elliptical cones.

46. (Canceled)

48-52. -52. (Canceled)

56-61. -61. (Canceled)

63-70. -70. (Canceled)

71. A method of reading a bar code comprising:

forming an image of a bar code, having at least 8 symbols with a camera from a distance of more than 10 meters; and

determining the symbols represented by the bar code.

72. (Canceled)

73. A method of reading a bar code comprising:

forming an image of a bar code with a camera from a distance of more than 10 meters; and

determining the symbols represented by the bar code,

wherein the bar code is comprised in a retro-reflected image and including illuminating the bar code with light from a controllable light source; and

wherein the retro-reflected image is reflected with a offset angle relative to the angle of incidence of the illumination from the light source.

74. A method according to claim 73 wherein the distance is more than 15 meters.

75. A method according to claim 73 wherein the distance is more than 20 meters.

76. A method according to claim 73 wherein the distance is more than 25 meters.

77. A method according to claim 73 wherein the bar code is formed on a credit card sized substrate.

78. A method according to claim 77 wherein the bar code includes at least 8 symbols.