Light detecting and angle of view compensation for optical devices and method

• US 20050007504A1
• Filed: 07/08/2004
• Published: 01/13/2005
• Est. Priority Date: 07/08/2003
• Status: Active Grant

• Current Assignee: Taroko International Co., Ltd.
• Original Assignee: Lightswitch Safety Systems Incorporated
• Inventors: Fergason, John D.
• Granted Patent: US 7,501,613 B2
• Time in Patent Office: Days
• US Class Current: 349/14
• CPC Class Codes: G01S 3/783 using amplitude comparison of signals derived from static detectors or detector systems
• CPC Class Codes: G02F 1/13318 Circuits comprising a photodetector

Abstract

A control for a controllable optical device, such as an auto-darkening lens (ADL), such as used in welding helmets, respirators, or other device, includes a sensor sensing the direction of incident light and a control circuit responsive to incident direction information to provide for control of the optical device. Based on at least one of incident direction of light and light intensity a the shade characteristics of the ADL or the like can be controlled and maintained while a person wearing the ADL may move the head to different orientations. Several fixed photosensor arrangements and dynamic systems may be used to sense incident light direction and whether the incident light is a point source. A method of detecting direction of incident light and whether the incident light is from a point source, and of controlling an ADL or the like based on direction and/or intensity of incident light.

Claims

1. A control for a controllable optical device, comprising

a sensor to sense the incident direction of incident light,

a control circuit responsive to incident direction information to provide for control of the optical device.

2. The control of claim 1, wherein the optical device is an auto-darkening lens.

3. The control of claim 2, wherein the control circuit provides for shade adjustment control for the auto-darkening lens to maintain a desired shade for an auto-darkening lens for different directions of incident light.

4. The control of claim 2, and further comprising in combination therewith an auto-darkening welding lens as the optical device.

5. The control and auto-darkening welding lens of claim 3′

, wherein the lens is mounted in a helmet.

6. The control of claim 2, further comprising an input circuit providing for manual adjustment of shade of the auto-darkening lens.

7. The control of claim 1 and further comprising an auto-darkening lens having light transmission characteristics controllable by the control circuit.

8. The control of claim 1, said sensor comprising a photosensor.

9. The control of claim 8, said photosensor comprising a plurality of photosensors.

10. The control of claim 9, further comprising a light restricting opening limiting the direction at which light may impinge on one or more of said photosensors.

11. The control of claim 10, said light restricting opening comprising a tube.

12. The control of claim 10, said light restricting opening comprising an aperture.

13. The control of claim 12, said aperture comprising an elongate aperture.

14. The control of claim 13, a number of said photosensors arranged in a generally linear array and said elongate aperture extending in a direction generally perpendicular to the direction of said generally linear array.

15. The control of claim 14, said sensor comprising at least two arrangements of generally linear arrays of photosensors oriented relative to respective elongate apertures that are generally perpendicular to the respective arrays.

16. The control of claim 9, further comprising a lens for restricting the direction at which light impinges on the photosensors.

17. The control of claim 8, further comprising a shutter to control light incident on the sensor.

18. The control of claim 17, said shutter comprising a movable aperture.

19. The control of claim 18, further comprising a motor for moving the aperture.

20. The control of claim 19, said aperture being in a rotatable member, and said motor being operative to rotate said rotatable member.

21. The control of claim 20, said aperture comprising a generally circular opening in the rotatable member.

22. The control of claim 20, said aperture comprising a slot in the rotatable member.

23. The control of claim 20, said aperture comprising a helical slot.

24. The control of claim 18, further comprising analyzer circuit responsive to outputs from the photosensor and the relative location of the aperture to the photosensor to provide an indication of incident light direction.

25. The control of claim 18, further comprising analyzer circuit responsive to outputs from the photosensor and the relative location of the aperture to the photosensor to provide an indication of whether the incident light is from at least one point source of light.

26. The control of claim 1, and further comprising in combination therewith as an optical device at least one of an auto-darkening welding lens, a welding helmet, a respirator, an auto-darkening lens, a lens, safety eye glasses, and eye glasses.

27. An auto-darkening lens system, comprising

a liquid crystal shutter, including a liquid crystal cell and associated polarizers,

a detector for detecting the direction of incident light on the liquid crystal shutter, and

a circuit for driving the liquid crystal shutter to respective shades of light transmission according to the direction of such incident light.

28. A method of operating an optical device, comprising

providing information representative of incident direction of light, and

adjusting a characteristic of the optical device according to such incident direction.

29. The method of claim 28, wherein the optical device is an auto-darkening lens and the adjusting of a characteristic comprises adjusting light transmission.

30. A method of detecting the angle of incident light, comprising limiting the paths of light to a number of respective photosensors.

31. The method of claim 30, further comprising comparing the outputs of a number of the photosensors as an indication of the direction of incident light.

32. The method of claim 31, further comprising using such comparison to determine whether incident light is from a point source of light.

33. A method of determining whether incident light is generally uniformly distributed ambient light or light from at least one point source of light, comprising comparing the outputs representative of light incident on a number of photosensors to determine whether there is a substantial peak at one or a number of the photosensors relative to the intensity of light on others of the photosensors.

34. An optical filter or lens, comprising a detector to detect the direction of incident light, and an active adjustment for the filter or lens as a function of the direction of incident light.

35. The optical filter or lens of claim 34, said filter comprising an auto-darkening lens, and the active adjustment comprising an adjustment for light transmission through the lens.

36. The optical filter or lens of claim 34, said detector comprising a number of photosensors.

37. The optical filter or lens of claim 36, said detector comprising a circuit for determining from the photosensors the direction of incident light and whether the incident light is from a point source of light.

38. The optical filter or lens of claim 37, said circuit comprising a comparator.

39. The optical filter or lens of claim 34, comprising a camera lens.

40. A light sensor, comprising

a generally linear array of photosensors, and

an aperture arranged relative to the generally linear array to pass light from a light source to a limited number of the photosensors.

41. The sensor of claim 40, said aperture including a lens.

42. The sensor of claim 40, said aperture including a light transmitting window.

43. The sensor of claim 40, said limited number of the photosensors comprising one photosensor.

44. The sensor of claim 40, said aperture comprising a slit.

45. The sensor of claim 44, said slit comprising a generally linear slit in a wall that blocks at least some light incident thereon while such light may transmit through said slit.

46. The sensor of claim 45, said slit being in a wall of a light blocking housing.

47. The sensor of claim 45 said slit being generally non-parallel to the general directional extent of the generally linear array.

48. The sensor of claim 47, said slit being generally perpendicular to the general directional extent of the generally linear array.

49. The sensor of claim 40, and further comprising circuitry to detect output from the photosensors.

50. The sensor of claim 49, said circuitry comprising a circuit to detect whether light incident on one or several of the photosensors is significantly greater than ambient light incident on a larger number of photosensors.

51. An auto-darkening lens including the sensor of claim 49 and a controllable shutter operative under control of said circuitry.

52. An auto-darkening lens including the sensor of claim 40 and a controllable shutter.

53. The sensor of claim 40, and further comprising a further light sensor including a further generally linear array of photosensors oriented generally in non-parallel relation to the first-mentioned generally linear array of photosensors, and a respective aperture for restricting light input to the further generally linear array of photosensors.

54. The sensor of claim 53, said respective generally linear arrays being generally perpendicular to each other, and said apertures comprising respective generally linear slits, each being positioned relative in generally perpendicularly relation to a respective generally linear array of photosensors.

55. The sensor of claim 54 further comprising circuitry responsive to said photosensors to distinguish between generally ambient light and a point light source.

56. The sensor of claim 55, said circuitry being operable to detect the location of a point light source relative to said light sensors.

57. A light sensor for detecting location of a light source, comprising first and second light detectors, each light detector including a light transmitting opening and a number of light sensors arranged in a generally linear arrangement, the linear arrangement of one light detector being generally non-parallel to the linear arrangement of the other light detector.

58. The sensor of claim 57, wherein said light sensors are arranged in respective linear arrays that are generally perpendicular to each other.

59. The sensor of claim 57, said light transmitting opening of each light detector being arranged relative to light sensors thereof to allow ambient light to illuminate a number of light sensors in respective linear arrangement thereof and to limit the light from a point light source to illuminate a smaller number of light sensors of such generally linear arrangement thereof.

60. The sensor of claim 59 wherein said smaller number of light sensors is one.

61. The sensor of claim 57, said light transmitting opening comprising a slit.

62. The sensor of claim 61, wherein said slit is generally linear.

63. The sensor of claim 62, wherein said slit is generally perpendicular to the generally linear arrangement sensors.

64. The sensor of claim 57, further comprising a housing for blocking light to said light detectors, said light transmitting opening being an opening in said housing.

65. The sensor of claim 64, said housing comprising of respective housing for each of said light detectors.

66. The sensor of claim 57, said light sensors comprising photosensitive diodes.

67. The sensor of claim 57, further comprising circuitry to respond to electrical outputs from said light detectors to sense a peak output compared to the approximately average output.

68. The sensor of claim 67, wherein the detecting of such peak is indicative of light directed from a point source through said light transmitting opening.

69. A method of detecting light, comprising

directing light through an opening to a generally linear arrangement of light sensors, whereby the intensity of light on one or several light sensors relative to the intensity of light on a number of other sensors is indicative of the direction of light through the opening.

70. The method of claim 69, said directing light through an opening comprising directing light through a slit, whereby ambient light is approximately uniformly distributed over a number of light sensors and light from a point light source illuminates a reduced number of light sensors.

71. The method of claim 69, further comprising detecting a peak output from at least one of the light sensors relative to the output from a number of other light sensors.

72. A method of detecting light, comprising

directing light through an opening to a generally linear arrangement of light sensors, whereby the intensity of light on one or several light sensors relative to the intensity of light on a number of other sensors is representative of detecting a point light source.

73. A method of detecting a point source of light, comprising

directing light through a light transmitting opening to a generally linear arrangement of light detectors, whereby ambient light illuminates a number of light sensors and light from a point source of light illuminates a reduced number of light sensors.

74. The method of claim 73, said directing light comprising directing light through a generally linear slit that is arranged in a non-parallel relation to the generally linear extend of the generally linear arrangement detectors.

75. A method of detecting the direction of incident light from a generally point light source comprising carrying out the method of claim 74 to detect one direction, and separately carrying out the method of claim 74 to determine a different direction, and comparing the information from both directions as an indication of the direction of light from the point light source.