Optical sensor device

• US 5,844,682 A
• Filed: 03/20/1995
• Issued: 12/01/1998
• Est. Priority Date: 03/25/1994
• Status: Expired due to Fees

• Current Assignee: Omron Corporation
• Original Assignee: Omron Corporation
• Inventors: Ekawa, Kouichi, Yasuda, Naru, Hosokawa, Hayami, Kiyomoto, Hironobu
• Primary Examiner(s): Font, Frank G.
• Assistant Examiner(s): Ratliff, Reginald A.
• Application Number:
  US08/406,540
• Time in Patent Office: 1,352 Days
• Field of Search: 356/356, 356/369, 356/385, 356/73.1, 356/237
• US Class Current: 356/237.1
• CPC Class Codes: B60H 1/00785 by the detection of humidity or frost
• CPC Class Codes: B60H 2003/0683 the quality of the filter or the air being checked
• CPC Class Codes: B60H 3/06 Filtering B60H3/0078 takes precedence
• CPC Class Codes: B60S 1/0818 including control systems responsive to external conditions, e.g. by detection of moisture, dirt or the like
• CPC Class Codes: B60S 1/0833 Optical rain sensor
• CPC Class Codes: B60T 8/17 Using electrical or electronic regulation means to control braking detecting or indicating faulty operation B60T8/885
• CPC Class Codes: G01N 21/21 Polarisation-affecting properties G01N21/19 takes precedence
• CPC Class Codes: G02B 27/283 used for beam splitting or combining

Abstract

Whether or not an object is present, the surface state of the object, the material constituting the object and the presence of scattering bodies are discriminated through a simple arrangement which includes a light-emitting element for projecting light upon an object to be sensed, and a polarization beam splitter upon which light reflected from the object (or light transmitted through or scattered from the object) impinges. Reflected light from the polarization beam splitter is received by a first light-receiving element, and transmitted light from the polarization beam splitter is received by a second light-receiving element. The aforesaid discrimination is performed on the basis of the value of S/P, S-P, S-kP or (S-P)/(S+P), where S and P represent light-reception signals from the first and second light-receiving elements, and k is a constant.

Claims

1. An optical sensor device comprising:

a light-projecting optical system for projecting light toward an object to be sensed, said projected light having the characteristic that it is not separated into a plurality of polarized light beams by said light-projecting optical system; and

a light-receiving optical system upon which reflected light, transmitted light or scattered light from the object to be sensed impinges;

said light-projecting optical system including at least a light-emitting element for outputting projected light; and

said light-receiving optical system including;

a polarization beam splitter for separating the reflected light, transmitted light or scattered light from the object into a first luminous flux which is mainly an s-polarized component with regard to the plane of incidence and a second luminous flux which is mainly a p-polarized component with regard to the plane of incidence, said polarization beam splitter having a light separating characteristic that is substantially constant within a range of angles of incidence used;

a first light-receiving element for receiving the first luminous flux; and

a second light-receiving element for receiving the second luminous flux.

2. The device according to claim 1, wherein said polarization beam splitter maintains said light separating characteristic, which is substantially constant within the range of angles of incidence used, within a range of wavelength spread exhibited by the projected light from said light-emitting element.

3. The device according to claim 1, further comprising discriminating means for outputting a signal relating to absence/presence of the object, surface property of the object or material constituting the object on the basis of outputs from said first and second light-receiving elements.

4. The device according to claim 1, wherein said light-projecting optical system is so arranged that the projected light is projected upon the surface of the object obliquely or substantially perpendicularly, and said light-receiving optical system is so arranged that the reflected light or scattered light from the surface of the object impinges upon it obliquely or substantially perpendicularly.

5. The device according to claim 1, wherein said light-projecting optical system and said light-receiving optical system are arranged to oppose each other in spaced-apart relation.

6. The device according to claim 1, wherein said light separating characteristic is represented by:

a first proportion expressed by a ratio of the quantity of light of the s-polarized component contained in the first luminous flux to the quantity of light of the s-polarized component incident upon said polarization beam splitter,

a second proportion expressed by a ratio of the quantity of light of the p-polarized component contained in the second luminous flux to the quantity of light of the p-polarized component incident upon said polarization beam splitter, or

the ratio of said first proportion to said second proportion;

at least one of said first proportion and said second proportion or said ratio between them being held substantially constant.

7. The device according to claim 6, wherein said first proportion, said second proportion and said ratio between them are represented by values obtained by multiplying a light-emission spectrum of said light-emitting element and a spectral sensitivity characteristic of said light-receiving element and by integrating the result with regard to wavelength.

8. The device according to claim 1, further comprising a projecting lens, wherein the projected light is projected upon being converged, diverged or collimated by said projecting lens.

9. The device according to claim 1, further comprising polarizing means for converting projected light composed of randomly polarized light to projected light composed of linearly polarized light.

10. The device according to claim 1, wherein light which has emerged from said light-emitting element is introduced to a projecting optical fiber and light which has emerged from an end face of said projecting optical fiber is projected.

11. The device according to claim 1, further comprising a light-receiving lens for converging light incident upon said light-receiving optical system.

12. The device according to claim 11, wherein said polarization beam splitter is placed in the optical path of the light converged by said light-receiving lens.

13. The device according to claim 1, wherein the first and second luminous fluxes are introduced to said first and second light-receiving elements, respectively, by respective light-receiving optical fibers.

14. The device according to claim 1, further comprising at least one of first analyzing means provided in front of said first light-receiving element for allowing transmission of s-polarized light and second analyzing means provided in front of said second light-receiving element for allowing transmission of p-polarized light.

15. The device according to claim 1, further comprising a reflector provided to face said polarization beam splitter on a side from which the first or second luminous flux emerges, wherein the first or second luminous flux is reflected from said reflector.

16. The device according to claim 1, wherein an opening for limiting incident light is formed in front of said light-receiving optical system.

52. An inspection method comprising the steps of:

discriminating the surface state of an article, conveyed on a conveyance path, by the optical sensor device described in claim 1; and

controlling the conveyance direction of the article on the basis of the results of discrimination.

53. An inspection method comprising the steps of:

discriminating the surface state of an article, conveyed on a conveyance path, by the optical sensor device described in claim 2; and

controlling the conveyance direction of the article on the basis of the results of discrimination.

54. An inspection method comprising the steps of:

discriminating the surface state of an article, conveyed on a conveyance path, by the optical sensor device described in claim 3; and

controlling the conveyance direction of the article on the basis of the results of discrimination.

55. An inspection method comprising the steps of:

discriminating the surface state of an article, conveyed on a conveyance path, by the optical sensor device described in claim 4; and

controlling the conveyance direction of the article on the basis of the results of discrimination.

56. An inspection method comprising the steps of:

discriminating the surface state of an article, conveyed on a conveyance path, by the optical sensor device described in claim 5; and

controlling the conveyance direction of the article on the basis of the results of discrimination.

57. An inspection method comprising the steps of:

discriminating the surface state of an article, conveyed on a conveyance path, by the optical sensor device described in claim 6; and

controlling the conveyance direction of the article on the basis of the results of discrimination.

58. An inspection method comprising the steps of:

discriminating the surface state of an article, conveyed on a conveyance path, by the optical sensor device described in claim 7; and

controlling the conveyance direction of the article on the basis of the results of discrimination.

59. An inspection method comprising the steps of:

discriminating the surface state of an article, conveyed on a conveyance path, by the optical sensor device described in claim 8; and

controlling the conveyance direction of the article on the basis of the results of discrimination.

60. An inspection method comprising the steps of:

discriminating the surface state of an article, conveyed on a conveyance path, by the optical sensor device described in claim 9; and

controlling the conveyance direction of the article on the basis of the results of discrimination.

61. An inspection method comprising the steps of:

discriminating the surface state of an article, conveyed on a conveyance path, by the optical sensor device described in claim 10; and

controlling the conveyance direction of the article on the basis of the results of discrimination.

62. An inspection method comprising the steps of:

discriminating the surface state of an article, conveyed on a conveyance path, by the optical sensor device described in claim 11; and

controlling the conveyance direction of the article on the basis of the results of discrimination.

63. An inspection method comprising the steps of:

discriminating the surface state of an article, conveyed on a conveyance path, by the optical sensor device described in claim 12; and

controlling the conveyance direction of the article on the basis of the results of discrimination.

64. An inspection method comprising the steps of:

discriminating the surface state of an article, conveyed on a conveyance path, by the optical sensor device described in claim 13; and

controlling the conveyance direction of the article on the basis of the results of discrimination.

65. An inspection method comprising the steps of:

discriminating the surface state of an article, conveyed on a conveyance path, by the optical sensor device described in claim 14; and

controlling the conveyance direction of the article on the basis of the results of discrimination.

66. An inspection method comprising the steps of:

discriminating the surface state of an article, conveyed on a conveyance path, by the optical sensor device described in claim 15; and

controlling the conveyance direction of the article on the basis of the results of discrimination.

67. An inspection method comprising the steps of:

discriminating the surface state of an article, conveyed on a conveyance path, by the optical sensor device described in claim 16; and

controlling the conveyance direction of the article on the basis of the results of discrimination.

17. An optical sensor device comprising:

a light-projecting optical system for projecting light toward an object to be sensed, said projected light having the characteristic that it is not separated into a plurality of polarized light beams by said light-projecting optical system; and

a light-receiving optical system upon which reflected light, transmitted light or scattered light from the object to be sensed impinges;

said light-projecting optical system including at least a light-emitting element for outputting projected light; and

said light-receiving optical system including;

a polarization beam splitter for separating the reflected light, transmitted light or scattered light from the object into a first luminous flux which is mainly an s-polarized component with regard to the plane of incidence and a second luminous flux which is mainly a p-polarized component with regard to the plane of incidence, said polarization beam splitter having a light separating characteristic that is substantially constant within a range of wavelength spread exhibited by the projected light from said light-emitting element;

a first light-receiving element for receiving the first luminous flux; and

a second light-receiving element for receiving the second luminous flux.

18. The device according to claim 17, further comprising discriminating means for outputting a signal relating to absence/presence of the object, surface property of the object or material constituting the object on the basis of outputs from said first and second light-receiving elements.

19. The device according to claim 17, wherein said light-projecting optical system is so arranged that the projected light is projected upon the surface of the object obliquely or substantially perpendicularly, and said light-receiving optical system is so arranged that the reflected light or scattered light from the surface of the object impinges upon it obliquely or substantially perpendicularly.

20. The device according to claim 17, wherein said light-projecting optical system and said light-receiving optical system are arranged to oppose each other in spaced-apart relation.

21. The device according to claim 17, wherein said light separating characteristic is represented by:

a first proportion expressed by a ratio of the quantity of light of the s-polarized component contained in the first luminous flux to the quantity of light of the s-polarized component incident upon said polarization beam splitter,

a second proportion expressed by a ratio of the quantity of light of the p-polarized component contained in the second luminous flux to the quantity of light of the p-polarized component incident upon said polarization beam splitter, or

the ratio of said first proportion to said second proportion;

at least one of said first proportion and said second proportion or said ratio between them being held substantially constant.

22. The device according to claim 21, wherein said first proportion, said second proportion and said ratio between them are represented by values obtained by multiplying a light-emission spectrum of said light-emitting element and a spectral sensitivity characteristic of said light-receiving element and by integrating the result with regard to wavelength.

23. The device according to claim 17, further comprising a projecting lens, wherein the projected light is projected upon being converged, diverged or collimated by said projecting lens.

24. The device according to claim 17, further comprising polarizing means for converting projected light composed of randomly polarized light to projected light composed of linearly polarized light.

25. The device according to claim 17, wherein light which has emerged from said light-emitting element is introduced to a projecting optical fiber and light which has emerged from an end face of said projecting optical fiber is projected.

26. The device according to claim 17, further comprising a light-receiving lens for converging light incident upon said light-receiving optical system.

27. The device according to claim 26, wherein said polarization beam splitter is placed in the optical path of the light converged by said light-receiving lens.

28. The device according to claim 17, wherein the first and second luminous fluxes are introduced to said first and second light-receiving elements, respectively, by respective light-receiving optical fibers.

29. The device according to claim 17, further comprising at least one of first analyzing means provided in front of said first light-receiving element for allowing transmission of s-polarized light and second analyzing means provided in front of said second light-receiving element for allowing transmission of p-polarized light.

30. The device according to claim 17, further comprising a reflector provided to face said polarization beam splitter on a side from which the first or second luminous flux emerges, wherein the first or second luminous flux is reflected from said reflector.

31. The device according to claims 17, wherein an opening for limiting incident light is formed in front of said light-receiving optical system.

68. An inspection method comprising the steps of:

discriminating the surface state of an article, conveyed on a conveyance path, by the optical sensor device described in claim 17; and

controlling the conveyance direction of the article on the basis of the results of discrimination.

69. An inspection method comprising the steps of:

discriminating the surface state of an article, conveyed on a conveyance path, by the optical sensor device described in claim 18; and

controlling the conveyance direction of the article on the basis of the results of discrimination.

70. An inspection method comprising the steps of:

discriminating the surface state of an article, conveyed on a conveyance path, by the optical sensor device described in claim 19; and

controlling the conveyance direction of the article on the basis of the results of discrimination.

32. An optical sensor device comprising:

a light-projecting optical system for projecting light toward an object to be sensed, said projected light having the characteristic that it is not separated into a plurality of polarized light beams by said light-projecting optical system; and

a light-receiving optical system upon which reflected light, transmitted light or scattered light from the object to be sensed impinges;

said light-projecting optical system including at least a light-emitting element for outputting projected light; and

said light-receiving optical system including;

a polarization beam splitter for separating the reflected light, transmitted light or scattered light from the object into a first luminous flux which is mainly an s-polarized component with regard to the plane of incidence and a second luminous flux which is mainly a p-polarized component with regard to the plane of incidence;

a first light-receiving element for receiving the first luminous flux; and

a second light-receiving element for receiving the second luminous flux.

33. The device according to claim 32, further comprising discriminating means for outputting a signal relating to absence/presence of the object, surface property of the object or material constituting the object on the basis of outputs from said first and second light-receiving elements.

35. The method according to claim 32, wherein said polarization beam splitter maintains said light separating characteristic, which is substantially constant within the range of angles of incidence used, within a range of wavelength spread exhibited by the projected light.

38. An object identification apparatus in which the optical sensor device described in claim 32 is placed on an object conveyance path and objects conveyed on said conveyance path are identified on the basis of an output signal from said optical sensor device.

39. A printing apparatus in which the optical sensor device described in claim 32 is placed on a conveyance path of a printing medium and an edge or positional offset of the printing medium is sensed on the basis of an output signal from said optical sensor device.

40. The printing apparatus according to claim 39, wherein said optical sensing device is held so as to move together with a printing head.

41. A printing apparatus comprising:

the optical sensor device described in claim 32;

discriminating means for discriminating the type of a printing medium on the basis of an output signal from said optical sensor device; and

control means for controlling printing conditions on the basis of results of discrimination performed by said discriminating means.

42. An air conditioner comprising:

the optical sensor device, which is described in claim 32, arranged so as to discriminate the surface state of a condensation medium or frost medium; and

control means for controlling air-conditioning running conditions on the basis of an output signal from said optical sensor device.

43. A humidity control apparatus comprising:

a heat exchanger;

the optical sensor device, which is described in claim 32, for discriminating the surface state of said heat exchanger; and

a control unit for controlling running conditions on the basis of an output signal from said optical sensor device.

44. A vehicle comprising:

the optical sensor device, which is described in claim 32, so arranged as to discriminate the surface state on the inner side of a window glass of the vehicle;

defogging means for eliminating fogging of said window glass; and

control means for controlling said defogging means on the basis of an output signal from said optical sensor device.

45. A vehicle comprising:

the optical sensor device, which is described in claim 32, so arranged as to discriminate the surface state on the outer side of a window glass of the vehicle;

a window wiper device for cleaning the surface on the outer side of said window glass; and

control means for controlling the operation of said window wiper device on the basis of an output signal from said optical sensor device.

46. A vehicle comprising:

the optical sensor device, which is described in claim 32, so arranged as to discriminate the state of a road surface;

operating-state detecting means for detecting the state in which the vehicle is being operated; and

control means for controlling drive of an actuator, which is related to a driving operation of the vehicle, on the basis of results of discriminating the road surface by said optical sensor device and results of detecting the operating state by said operating-state detecting means.

47. A vehicle comprising:

the optical sensor device, which is described in claim 32, so arranged and constructed as to sense a mark or the like represented on a road surface;

warning means for warning an individual driving the vehicle; and

control means for controlling said warning means on the basis of an output signal from said optical sensor device.

48. A vehicle comprising:

the optical sensor device, which is described in claim 32, for sensing deviation from a guide provided along a path of travel; and

means for performing steering on the basis of a detection signal from said optical sensor device.

49. A bank note handling apparatus comprising:

the optical sensor device, which is described in claim 32, for sensing the surface of a bank note; and

control means for controlling operation of the apparatus on the basis of an output from said sensor device.

50. An offset printing apparatus comprising:

a printing roller for fixing a printing original sheet;

wetting-water supply means for supplying the printing original sheet with wetting water;

the optical sensor device, which is described in claim 32, for sensing the surface of the printing original sheet; and

control means for controlling said wetting-water supply means on the basis of an output from said optical sensor device.

51. An inspection apparatus comprising:

the optical sensor device, which is described in claim 32, so arranged as to discriminate the surface state of an article conveyed on a conveyance path;

direction changing means for changing conveyance direction of the conveyed article; and

means for controlling said direction changing means on the basis of results of discrimination by said optical sensor device.

34. A sensing method comprising the steps of:

projecting projected light toward an object to be sensed, said projected light having the characteristic that it is not separated into a plurality of polarized light beams by said light-projecting optical system;

using a polarization beam splitter having a light separating characteristic that is substantially constant within a range of angles of incidence used;

separating reflected light, transmitted light or scattered light from the object into a first luminous flux which is mainly an s-polarized component with regard to the plane of incidence of said polarization beam splitter and a second luminous flux which is mainly a p-polarized component with regard to the plane of incidence of said polarization beam splitter; and

outputting a signal relating to absence/presence of the object, surface property of the object or material constituting the object on the basis of quantity of light of the first luminous flux and quantity of light of the second luminous flux.

36. A sensing method comprising the steps of:

projecting projected light toward an object to be sensed, said projected light having the characteristic that it is not separated into a plurality of polarized light beams by said light-projecting optical system;

using a polarization beam splitter having a light separating characteristic that is substantially constant within a range of wavelength spread exhibited by the projected light;

separating reflected light, transmitted light or scattered light from the object into a first luminous flux which is mainly an s-polarized component with regard to the plane of incidence of said polarization beam splitter and a second luminous flux which is mainly a p-polarized component with regard to the plane of incidence of said polarization beam splitter; and

outputting a signal relating to absence/presence of the object, surface property of the object or material constituting the object on the basis of quantity of light of the first luminous flux and quantity of light of the second luminous flux.

37. A sensing method comprising the steps of:

projecting projected light toward an object to be sensed, said projected light having the characteristic that it is not separated into a plurality of polarized light beams by said light-projecting optical system;

separating, by using a polarization beam splitter, reflected light, transmitted light or scattered light from the object into a first luminous flux which is mainly an s-polarized component with regard to the plane of incidence of said polarization beam splitter and a second luminous flux which is mainly a p-polarized component with regard to the plane of incidence of said polarization beam splitter; and

outputting a signal relating to absence/presence of the object, surface property of the object or material constituting the object on the basis of quantity of light of the first luminous flux and quantity of light of the second luminous flux.

71. An optical sensor device comprising:

a light-projecting optical system for projecting light toward an object to be sensed; and

a light-receiving optical system upon which reflected light, transmitted light or scattered light from the object to be sensed impinges;

said light-projecting optical system including at least a light-emitting element for outputting projected light; and

said light-receiving optical system including;

a polarization beam splitter for separating the reflected light, transmitted light or scattered light from the object into a first luminous flux which is mainly an s-polarized component with regard to the plane of incidence and a second luminous flux which is mainly a p-polarized component with regard to the plane of incidence, said polarization beam splitter having a light separating characteristic that is substantially constant within a range of angles of incidence used, and wherein said light separating characteristic is represented by;

a first proportion expressed by a ratio of the quantity of light of the s-polarized component contained in the first luminous flux to the quantity of light of the s-polarized component incident upon said polarization beam splitter,

a second proportion expressed by a ratio of the quantity of light of the p-polarized component contained in the second luminous flux to the quantity of light of the p-polarized component incident upon said polarization beam splitter, or

the ratio of said first proportion to said second proportion;

at least one of said first proportion and said second proportion or said ratio between them being held substantially constant;

a first light-receiving element for receiving the first luminous flux; and

a second light-receiving element for receiving the second luminous flux.

72. The device according to claim 71, wherein said first proportion, said second proportion and said ratio between them are represented by values obtained by multiplying a light-emission spectrum of said light-emitting element and a spectral sensitivity characteristic of said light-receiving element and by integrating the result with regard to wavelength.

73. An optical sensor device comprising:

a light-projecting optical system for projecting light toward an object to be sensed; and

a light-receiving optical system upon which reflected light, transmitted light or scattered light from the object to be sensed impinges;

a light-receiving lens for converging light incident upon said light-receiving optical system;

said light-projecting optical system including at least a light-emitting element for outputting projected light; and

said light-receiving optical system including;

a polarization beam splitter for separating the reflected light, transmitted light or scattered light from the object into a first luminous flux which is mainly an s-polarized component with regard to the plane of incidence and a second luminous flux which is mainly a p-polarized component with regard to the plane of incidence, said polarization beam splitter having a light separating characteristic that is substantially constant within a range of angles of incidence used;

a first light-receiving element for receiving the first luminous flux; and

a second light-receiving element for receiving the second luminous flux.

74. An optical sensor device comprising:

a light-projecting optical system for projecting light toward an object to be sensed; and

a light-receiving optical system upon which reflected light, transmitted light or scattered light from the object to be sensed impinges;

said light-projecting optical system including at least a light-emitting element for outputting projected light; and

said light-receiving optical system including;

a polarization beam splitter for separating the reflected light, transmitted light or scattered light from the object into a first luminous flux which is mainly a p-polarized component with regard to the plane of incidence, said polarization beam splitter having a light separating characteristic that is substantially constant within a range of angles of incidence used;

a first light-receiving element for receiving the first luminous flux;

a second light-receiving element for receiving the second luminous flux; and

,

a reflector provided to face said polarization beam splitter on a side from which the first or second luminous flux emerges, wherein the first or second luminous flux is reflected from said reflector.