Optical displacement sensor utilizing optical diffusion

• US 5,376,785 A
• Filed: 10/02/1992
• Issued: 12/27/1994
• Est. Priority Date: 10/02/1992
• Status: Expired due to Term

• Current Assignee: Commissariat a L'Energie Atomique (AES Corporation), Institut National de La Recherche Agronomique, Institut Pasteur, Philip K. Chin
• Original Assignee: Philip K. Chin
• Inventors: Lynch, P. Michael, Chin, Philip K.
• Primary Examiner(s): Westin, Edward P.
• Assistant Examiner(s): Allen, Stephone B.
• Application Number:
  US07/955,932
• Time in Patent Office: 816 Days
• Field of Search: 250/221, 250/227.21, 250/229, 250/231.13, 250/214 PR, 250/561, 341/31
• US Class Current: 250/214.0PR
• CPC Class Codes: A61M 2205/3306 Optical measuring means
• CPC Class Codes: A61M 2205/3379 Masses, volumes, levels of fluids in reservoirs, flow rates
• CPC Class Codes: A61M 2205/3389 Continuous level detection A61M2205/3393 takes precedence
• CPC Class Codes: A61M 5/1684 by detecting the amount of infusate remaining, e.g. signalling end of infusion
• CPC Class Codes: A61M 5/31568 Means keeping track of the total dose administered, e.g. since the cartridge was inserted
• CPC Class Codes: A61M 5/31573 Accuracy improving means
• CPC Class Codes: G01D 5/30 the beams of light being detected by photocells
• CPC Class Codes: G01D 5/34 the beams of light being detected by photocells

Abstract

An optical displacement sensor is disclosed for use in robotic applications. The sensor can be used to examine the shape and surface texture of an object. In the embodiment which includes a compressible means of known spring constant, the sensor can be used to measure contract force. The position sensor uses an electro-optical displacement transducer to convert a displacement into an electrical output. The sensor utilizes a phototransistor to measure light emitted by an infrared light emitting diode. The amount of light received from by the phototransistor is varied by the displacement of the contact probe, or shadow rod.

Claims

1. An optical displacement transducer, comprising:

an elongated hollow housing having a central chamber therein;

a partition dividing the central chamber into a first portion and a second portion, said partition having a central opening therein;

a light emitting means mounted in the first portion of the central chamber;

a light receiving means mounted opposite said light emitting means in the first portion of the central chamber; and

an axially movable light blocking means extending between the light emitting means and the light receiving means for intermittently, at least partially, blocking the light emitted by said light emitting means.

2. The device of claim 1, wherein said light blocking means moves between a fully extended position, allowing substantially all light emitted by the light emitting means to travel to the light receiving means, and a second position at least partially blocking the light.

3. The device of claim 1, further comprising a compressible means positioned within the second portion of the central chamber.

4. The device of claim 3, wherein said light blocking means has an inner end, and said compressible means contacts said inner end, continuously urging the light blocking means into a fully extended position.

5. The device of claim 1, wherein said light blocking means comprises an elongated rod having a light transmitting window made adjacent to one of its ends.

6. The device of claim 5, wherein said central opening is sized and shaped to receive the rod in a sliding engagement therethrough.

7. The device of claim 5, wherein said housing has a closed end blocked by an end plate having an opening, through which the rod protrudes outwardly from the housing.

8. The device of claim 5, wherein said elongated rod has an inner end which carries an end plate thereon, said end plate frictionally contacting inner walls of the housing.

9. The device of claim 8, wherein said end plate contacts the partition, said partition limiting movement of the rod outwardly.

10. The device of claim 1, wherein said light emitting means comprises a light emitting diode.

11. The device of claim 10, wherein said diode is an infrared light emitting diode.

12. The device of claim 10, wherein said light emitting means further comprises an emitter light pipe housing the light emitting diode therein.

13. The device of claim 12, wherein said emitter light pipe has a surface which faces the light blocking means, said surface having a translucent portion allowing light to travel out of the emitter light pipe.

14. The device of claim 1, wherein said light receiving means comprises a phototransistor.

15. The device of claim 14, wherein said phototransistor is an infrared phototransistor.

16. The device of claim 14, wherein said light receiving means further comprises a receiving light pipe which houses the phototransistor therein.

17. The device of claim 16, wherein said receiving light pipe has a surface which faces the light blocking means, said surface having a translucent portion allowing light to travel to the phototransistor through the receiving light pipe.

18. An optical displacement transducer, comprising:

an elongated hollow housing having a central chamber therein;

a partition dividing the central chamber into a first portion and a second portion, said partition having a central opening therein;

a light emitting means mounted in the first portion of the central chamber, said light emitting means comprising a light emitting diode mounted within an emitter light pipe;

a light receiving means mounted opposite said light means in the first portion of the central chamber, said light receiving means comprising a phototransistor and a receiving light pipe;

an axially movable light blocking means extending between the emitter light pipe and the receiving light pipe, said light blocking means comprising an elongated rod having a light transmitting window made adjacent to one of its ends, an inner end of the rod carrying an end plate which contacts the partition to limit travel of the rod outwardly from the housing, said elongated rod moving between a first position, when said light transmitting window is in alignment with the emitter light pipe and the receiving light pipe, and a second position when said light transmitting window is in at least partial misalignment with the emitter light pipe and the receiving light pipe.

19. The device of claim 18, wherein said emitter light pipe has a surface which faces the elongated rod, at least a portion of said surface being translucent to allow light to travel out of the emitter light pipe.

20. The device of claim 19, wherein said receiving light pipe has a surface which faces the elongated rod, at least a portion of said surface being translucent to allow light to travel into the receiving light pipe.

21. The device of claim 18, wherein said light emitting diode is an infrared light emitting diode.

22. The device of claim 18, wherein said phototransistor is an infrared phototransistor.

23. The device of claim 18, wherein said central opening in the partition is sized and shaped to receive the rod in a sliding engagement therethrough.

24. The device of claim 18, wherein said housing has a closed end blocked by an end plate having an opening, through which the rod protrudes outwardly from the housing.

25. An optical displacement transducer, comprising:

an elongated hollow housing having a central chamber therein;

a partition dividing the central chamber into a first portion and a second portion, said partition having a central opening therein;

a compressible means positioned within the second portion of the central chamber;

a light emitting means mounted in the first portion of the central chamber;

a light receiving means mounted opposite said light emitting means in the first portion of the central chamber; and

an axially movable light blocking means extending between the light emitting means and the light receiving means for intermittently, at least partially, blocking the light emitted by said light emitting means.

26. The device of claim 25, wherein said light blocking means has an inner end, and said compressible means contacts said inner end, continuously urging the light blocking means into a fully extended position.

27. The device of claim 25, wherein said light blocking means is adapted for movement between a fully extended position, allowing substantially all light emitted by the light emitting means to travel to the light receiving means, and a second, compressed position, at least partially blocking the light.

28. The device of claim 25, wherein said light blocking means comprises an elongated rod having a light transmitting window adjacent to one of its ends.

29. The device of claim 28, wherein said elongated rod has an inner end which carries an inner end plate thereon, said inner end plate frictionally contacting the inner walls of the housing.

30. The device of claim 29, wherein said inner end plate has a surface, which contacts the partition, said partition limiting movement of the rod outwardly.

31. The device of claim 28, wherein said housing has a closed end blocked by an outer end plate which has an opening, through which the rod protrudes outwardly from the housing.

32. The device of claim 25, wherein said diode is an infrared light emitting diode.

33. The device of claim 32, wherein said light emitting means further comprises an emitter light pipe housing the light emitting diode therein.

34. The device of claim 33, wherein said emitter light pipe has a surface which faces the light blocking means, said surface having a translucent portion which allows light to travel out of the emitter light pipe.

35. The device of claim 34, wherein said light receiving means comprises a phototransistor.

36. The device of claim 35, wherein said phototransistor is an infrared phototransistor.

37. The device of claim 35, wherein said light receiving means further comprises a receiving light pipe which houses the phototransistor therein.

38. The device of claim 37, wherein said receiving light pipe has a surface which faces the light blocking means, said surface having a translucent portion which allows light to travel to the phototransistor through the receiving light pipe.

39. An optical displacement transducer device comprising:

a light emitting means for emitting a light flow;

a light receiving means for receiving the light flow mounted opposite said light emitting means; and

a means for intermittently blocking at least in part, the light flow from said light emitting means; and

a means associated with at least said light emitting means for distributing the light flow by diffusion.

40. An optical displacement transducer device, comprising:

a light emitting means for emitting a light flow;

a light receiving means for receiving the light flow mounted opposite said light emitting means, wherein said light emitting means comprises a housing having a light source positioned therein, said housing having a light permeable face in at least that portion thereof which faces the light receiving means; and

a means for intermittently blocking, at least in part, the light flow from said light emitting means.

41. The device of claim 40, wherein said housing has a rectangular solid shape, and an opening is formed in one end thereof for receiving said light source therein.

42. The device of claim 40, wherein said light permeable face has a perimeter, at least a portion of which is defined by a straight edge.

43. The device of claim 40, wherein said light receiving means comprises at least one body having a light sensor mounted therein, and a light permeable face formed in that portion of the body which faces the light permeable face of the light emitting housing.

44. The device of claim 43, wherein said light sensor is positioned in an end of the light receiving housing distant from the light permeable face.

45. An optical displacement transducer comprising:

a light emitting means for emitting a light flow;

a light receiving means for receiving the light flow mounted opposite said light emitting means, wherein said light emitting means comprises a housing and a light source connected to the housing in light transferring relationship, said housing being light permeable in at least a portion thereof for transmitting the light flow from said light source to an exterior of the housing; and

a means for intermittently blocking, at least in part, the light flow from said light emitting means.

46. The device of claim 45, wherein said light source is positioned in an end of the housing distant from said light permeable face.

47. The device of claim 45, wherein said light receiving means comprises at least one light receiving body having a light sensor mounted therein and a light permeable face formed in that portion of the body which faces the light permeable face of the light emitting means, the light flow travelling from the light source to the light sensor along a path having a generally C-shaped configuration.

48. An optical displacement transducer device, comprising:

a light emitting means for emitting a light flow;

a light receiving means for receiving the light flow mounted opposite said light emitting means, wherein said light receiving means comprises at least one body having a light permeable face formed in at least that portion of said at least one body which faces the light emitting means; and

a means for intermittently blocking, at least in part, the light flow from said light emitting means.

49. The device of claim 48, wherein said at least one body has a generally rectangular solid shape, one end of said at least one body being provided with an opening for retaining the light sensor therein.

50. The device of claim 48, wherein said light permeable face of said at least one body has a perimeter, at least a portion of which is defined by a straight edge.

51. An optical displacement transducer device comprising:

a light emitting means for emitting a light flow;

a light receiving means for receiving the light flow mounted opposite said light emitting means; and

a means for intermittently blocking, at least in part, the light flow from said light emitting means, wherein said light blocking means comprises at least one solid light impermeable member moving between a first position, at least partially blocking the light flow from the light emitting means and a second position, allowing substantially entire light flow to pass to the light receiving means.

52. The device of claim 51, wherein said at least one solid member moves between said light emitting means and said light receiving means.

53. The device of claim 51, wherein said at least one solid member is provided with a window which is moved in general co-alignment with the light flow when the solid member is in the first position to permit the light flow to pass therethrough.

54. The device of claim 53, wherein said at least one solid member is adapted for a linear movement in a plan generally parallel to normal axes of the light emitting means and the light receiving means.

55. The device of claim 53, wherein said window is generally sized and shaped to permit substantially entire light flow to pass therethrough.

56. The device of claim 53, wherein said window is generally sized and shaped to permit only a limited light flow to pass therethrough.

57. The device of claim 53, wherein said window has a longitudinal axis which is substantially parallel to a longitudinal axis of the solid member, and of said light emitting means and said light receiving means.

58. An optical displacement transducer, comprising:

a light emitting means comprising a housing having an interior chamber formed therein for housing a light source and a translucent face for channeling a light flow emitted by the light source to an exterior of the housing;

a light receiving means mounted opposite the housing and comprising a light receiving body having an interior chamber formed therein for receiving a light sensor therein to detect the amount of light received by the body, said body having a translucent face for channeling the light to the light sensor; and

a light blocking means mounted between the housing and the light receiving body and movable in a linear direction for intermittently blocking the light flow from the light source to the light sensor, said light blocking means comprising a solid member having a window therein to allow the light flow to pass therethrough.

59. The device of claim 58, wherein the light flow is channeled along a path having a general "C"-shape.