Color measuring spectrophotometer

• US 3,935,436 A
• Filed: 04/24/1973
• Issued: 01/27/1976
• Est. Priority Date: 04/24/1973
• Status: Expired due to Term

• Current Assignee: Greenwood Mills
• Original Assignee: Greenwood Mills
• Inventors: Wilcox, Lyle, Holschlag, deceased, Jerry B.
• Primary Examiner(s): Wise, Edward J.
• Application Number:
  US05/354,090
• Time in Patent Office: 1,008 Days
• Field of Search: 444/1, 356/177, 356/173, 356/96, 356/176, 356/244, 235/151.3, 235/151.35
• US Class Current: 356/320
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/0251 Colorimeters making use of an integrating sphere
• CPC Class Codes: G01J 3/0267 Sample holders for colorimetry
• CPC Class Codes: G01J 3/51 using colour filters
• CPC Class Codes: G01J 3/513 having fixed filter-detector pairs
• CPC Class Codes: G01J 3/524 Calibration of colorimeters

Abstract

A digital, abridged spectrophotometer with a detecting head defining a roughly spherical, reflective inner surface broken by a viewing port and a light source port with a number of filtered photodiodes mounted in the head for each receiving light from a sample or standard in the viewing port. A standard sheet of vitrolite is mounted on the housing for movement with a plunger, which trips a switch, to cover the viewing port, while a standard black sheet can be pivoted to cover the viewing port for the calibration which precedes each reading. A digital computer calculates the tristimulus values from the signals produced by the photodiodes and provides signals for a display of the color values.

Claims

1. A digital, abridged spectrophotometer comprising:

a detecting head with a housing defining a roughly spherical, reflective internal surface, a light source mounted for illuminating said internal surface, a viewing port for receiving a sample image to be analyzed, a plurality of photo-responsive devices each mounted for receiving light over the whole of said sort, a plurality of light filters each removing incident light except from a different band and each mounted so that output light is incident on one of said photoresponsive devices, and

digital computer means for determining the electrical conditions of said photo-responsive devices and calculating color values.

2. A spectrophotometer as in claim 1 wherein said detecting head further includes a movable member means, means mounting said movable member means for movement between an off port position and a port covering position, said member including a sheet of standard color material mounted on said member means for covering said viewing port when said member means is immediately over said viewing port in said port covering position.

3. A spectrophotometer as in claim 2 wherein said detecting head further includes means for urging said member means toward said off port position.

4. A spectrophotometer as in claim 2 wherein said detecting head further includes switch means mounted adjacent said movable member means for operating said computer means while said member means is in said port covering position.

5. A spectrophotometer as in claim 4 wherein said movable member means includes a plunger having a handle portion for engaging said switch means, a further portion being axially movable with respect to said handle portion, a first spring urging said further portion away from said viewing port, and a second spring urging said handle portion away from said viewing port.

6. A spectrophotometer as in claim 2 wherein said detecting head includes a pivotably mounted member mounted on said housing for movement to a position over said viewing port and then down covering said viewing port, a standard second color sheet mounted on said pivotably mounted member, and spring means urging said pivotably mounted member away from said viewing port and wherein said first sheet is vitrolite and said second sheet black.

7. A spectrophotometer as in claim 2 wherein said viewing port includes a clear glass pane.

8. A spectrophotometer as in claim 2 wherein said detecting head includes means for mounting said photo-responsive devices in said housing concentrically about an axis which substantially perpendicularly intersects the center of said viewing port.

9. A spectrophotometer as in claim 8 wherein said detecting means includes heating means mounted in said photo-responsive devices mounting means.

10. A spectrophotometer as in claim 2 wherein said housing has a light port for receiving light from said source and wherein said detecting means includes means for mounting said light source adjacent said light port.

11. A spectrophotometer as in claim 10 wherein said light source mounting means includes a plurality of fins for cooling.

12. A spectrophotometer as in claim 10 further including means for circulating air through said light source mounting means and past said housing for cooling.

13. A spectrophotometer as in claim 2 wherein said housing is provided with cooling fins.

14. A spectrophotometer as in claim 2 wherein said housing includes means for mounting said housing on a table.

15. A spectrophotometer as in claim 2 further including means for displaying color values.

16. A spectrophotometer as in claim 2 wherein said photo-responsive devices are photodiodes.

17. A spectrophotometer as in claim 16 wherein said photo-diodes span the color band between 4000 and 7000 Angstroms with separators of 200 Angstroms.

18. A spectrophotometer as in claim 2 wherein said standard sheet is vitrolite.

19. A spectrophotometer as in claim 2 wherein said movable member means includes a standard second color sheet and means for selecting one or the other of the first mentioned and second standard color sheets to cover said viewing port when said movable member means is in said port covering position.

20. A spectrophotometer as in claim 19 wherein one of said standard sheets is black and the other is of a substantially different color.

21. A spectrophotometer as in claim 19 wherein one of said standard color sheets is black and the other is vitrolite.

22. A digital abidged spectrophotometer as in claim 1 wherein said computer means includes means for calibrating from signals derived by said photo-responsive devices viewing a standard sample prior to each sample reading, means for providing a given time after calibration for sample reading and means for calculating reflectance and color quantifier values from the signals received from said photo-responsive devices during a sample reading.

23. A digital, abridged spectrophotometer comprising:

a detecting head having a housing providing a viewing port for receiving a sample to be color analyzed,

means, including substantially more than five photo-responsive devices each having light receiving means mounted inside said housing to receive incident light from said port with said devices being responsive to a different color band, for simultaneously providing exteriorly of said housing a corresponding number of output signals varying as a function of the respectively received incident light,

standardizing means including at least one standard color sample,

means for moving said standardizing means between a sample off port position and a sample port covering position, and

digital computer means for interrogating each of said photo-responsive devices and determining the color values of material over said viewing port including recalibration means responsive to each of said output signals for calculating the present reflectance equations respectively for said different color bands after said standardizing means has been moved to said port covering position and means operative automatically then on the basis of said present reflectance equations for determining in response to the instant output signals then received from said-photo-responsive devices the reflectance and color quantifier values of an unknown color sample of material covering said port.

24. A spectrophotometer as in claim 23 wherein said moving means includes a movable member means, and means mounting said movable member means for movement between said sample off port and sample port covering positions.

25. A spectrophotometer as in claim 24 wherein said detecting head further includes means for urging said member toward said off port position.

26. A spectrophotometer as in claim 24 wherein said detecting head further includes switch means mounted adjacent said movable member means for operating said computer means while said member means is in said port covering position.

27. A spectrophotometer as in claim 26 wherein said movable member means includes a plunger having a handle portion for engaging said switch means, a further portion being axially movable with respect to said handle portion, a first spring urging said further portion away from said viewing port, and a second spring urging said handle portion away from said viewing port.

28. A spectrophotometer as in claim 24 wherein said detecting head further includes a pivotably mounted member mounted on said housing for mvoement to a position over said viewing port and then down covering said viewing port, a standard second color sheet mounted on said pivotably mounted member, and spring means urging said pivotably mounted member away from said viewing port, and wherein said first sheet is vitrolite said second sheet black.

29. A spectrophotometer as in claim 24 wherein said viewing port includes a clear glass pane.

30. A spectrophotometer as in claim 24 wherein said detecting head includes means for mounting said photo-responsive devices in said housing concentrically about an axis which substantially perpendicularly intersects the center of said viewing port.

31. A spectrophotometer as in claim 30 wherein said detecting means includes heating means mounted in said photo-responsive devices mounting means.

32. A spectrophotometer as in claim 31 wherein said light source mounting means includes a plurality of fins for cooling.

33. A spectrophotometer as in claim 31 further including means for circulating air through said light source mounting means and past said housing for cooling.

34. A spectrophotometer as in claim 24 wherein said housing has a light port for receiving light from said source and wherein said detectig means includes means for mounting said light source adjacent said light port.

35. A spectrophotometer as in claim 24 wherein said housing is provided with cooling fins.

36. A spectrophotometer as in claim 24 wherein said housing includes means for mounting said housing on a table.

37. A spectrophotometer as in claim 24 further including means for displaying color values.

38. A spectrophotometer as in claim 24 wherein said photo-responsive devices are photo-diodes.

39. A spectrophotometer as in claim 38 wherein said photo-diodes span the color band between 4000 and 7000 Angstroms with separators of 200 Angstroms.

40. A spectrophotometer as in claim 24 wherein said standard sheet is vitrolite.

41. A spectrophotometer as in claim 23 wherein said one standard color sample is of one color and said standardizing means includes a second different colored standard color sample which is black,

said moving means being operative to move one of said standard samples and then the other to said port covering position,

said recalibration means being responsive to the plurality of outputs signals resulting from both of said standard samples being successively in said port covering position for calculating the said present reflectance equations for each said different color band based on the present amount of incident light received by said photoresponsive devices while both of said standard samples are successively covering said port,

said moving means being operative to move said standardizing means to said port covering position with said unknown color sample being between said port and one of said standard samples for the determination by said determinng means of the reflectance and color quantifier values of said unknown color sample.

42. A spectrophotometer as in claim 41 wherein said white one standard color sample is vitrolite and said recalibration means includes means for pre-storing reflectance values for each of said different color bands for each of said standard color samples and means for relating the photo-responsive device output signals resulting from the sampled vitrolite and black samples to the stored reflectance values respectively to effect the said present reflectance equations.

43. A digital abridged spectrophotometer for determining color values of material of unknown color comprising:

detecting means including a detecting head having a viewing port for receiving said material to be color analyzed,

said detecting means including source means for providing light over the visible spectrum inside said head and substantially more than five photo-responsive devices each having light receiving means mounted inside said head for receiving incident reflected light from said port with said devices being responsive over all said spectrum respectively to a different color band for simultaneously providing exteriorly of said head a corresponding number of signals varying as a function of the respectively received incident light,

standardizing means including two differently colored standard samples,

means for alternately moving each of said samples between a sample off port position and a sample port covering position during calibrating times and for moving one of said samples to said port covering position with said material therebetween during color analyzing times,

control means for interrogating each of said photoresponsive devices including digital computer means for calibrating from signals derived by said photo-responsive devices effectively viewing said standard samples alternately once for each color analyzing time,

means for alternately establishing said calibrating and analyzing times, and

means in said digital computer for calculating the color values from the signals received from said photoresponsive devices during said color analyzing times.

44. A spectrophotometer as in claim 43 wherein said detecting head further includes a housing, movable member means, means mounting said movable member means on said housing for movement between said sample off port and sample port covering positions.

45. A spectrophotometer as in claim 44 wherein said detecting head further includes means for urging said member toward said off port position.

46. A spectrophotometer as in claim 44 wherein said detecting head includes a pivotably mounted member mounted on said housing for movement to a position over said viewing port and then down covering said viewing port, and spring means urging said pivotably mounted member away from said viewing port, and wherein one sample is vitrolite and the other sample black.

47. A spectrophotometer as in claim 44 wherein said viewing port includes a clear glass pane.

48. A spectrophotometer as in claim 44 wherein said housing has a light port for receiving light from said source and wherein said detecting means includes means for mounting said light source adjacent said light port.

49. A spectrophotometer as in claim 44 further including means for displaying color values.

50. A spectrophotometer as in claim 44 wherein one of said standard samples is vitrolite and the other is black.

51. A digital abridged spectrophotometer comprising:

a detecting head including a plurality of photoresponsive devices each mounted for receiving incident light over a different color band and providing an output signal varying as a function of received light,

control means for interrogating each of said photoresponsive devices including means for calibrating from signals derived by said photo-responsive devices viewing a standard sample prior to each sample reading,

means for providing a given time after calibration for sample reading, and

means for calculating the color values from the signals received from said photo-responsive devices during a sample reading,

wherein said detecting head further includes a housing, movable member means, means mounting said movable member means on said housing for movement from a rest position to a position immediately over said viewing port, a sheet of standard color material mounted on said movable member means for covering said viewing port when said member means is immediately, over said viewing port, and switch means mounted adjacent said member for operating said control means when said standard sheet is covering said viewing port.

52. A spectrophotometer as in claim 51 wherein said member includes a plunger having a handle portion for engagig said switch means, a further portion being axially movable with respect to said handle portion, a first spring urging said further portion away from said viewing port, and a second spring urging said handle portion away from said viewing port.

53. A digital abridged spectrophotometer comprising:

a detecting head including a plurality of photoresponsive devices each mounted for receiving incident light over a different color band and providing an output signal varying as a function of received light,

control means for interrogating each of said photoresponsive devices including means for calibrating from signals derived by said photo-responsive devices viewing a standard sample prior to each sample reading,

means for providing a given time after calibration for sample reading, and

means for calculating the color values from the signals received from said photo-responsive devices during a sample reading,

wherein said detecting head further includes a housing, movable member means, means mounting said movable member means on said housing for movement from a rest position to a position immediately over said viewing port, a sheet of standard color material mounted on said movable member means for covering said viewing port when said member means is immediately over said viewing port, and means for mounting said photo-responsive devices in said housing concentrically about an axis which substantially perpendicularly intersects the center of said viewing port.

54. A spectrophotometer as in claim 53 wherein said detecting means includes heating means mounted in said photo-responsive devices mounting means.

55. A digital abridged spectrophotometer comprising:

a detecting head including a plurality of photoresponsive devices each mounted for receiving incident light over a different color band and providing an output signal varying as a function of received light,

control means for interrogating each of said photoresponsive devices including means for calibrating from signals derived by said photo-responsive devices viewing a standard sample prior to each sample reading,

means for providing a given time after calibration for sample reading, and

means for calculating the color values from the signals received from said photo-responsive devices during a sample reading

wherein said detecting head further includes a housing, movable member means on said housing for movement from a rest position to a position immediately over said viewing port, and a sheet of standard color material mounted on said movable member means for covering said viewing port when said member means is immediately over said viewing port,

wherein said housing has a light port for receiving light from said source, said detecting head includes means for mounting said light source adjacent said light port, and

said light source mounting means includes a plurality of fins for cooling.

56. A digital abridged spectrophotometer comprising:

a detecting head including a plurality of photoresponsive devices each mounted for receiving incident ligh over a different color band and providing an output signal varying as a function of received light,

control means for interrogating each of said photoresponsive devices includng means for calibrating from signals derived by said photo-responsive devices viewing a standard sample prior to each sample reading.

means for providing a given time after calibration for sample reading, and

means for calculating the color values from the signals received from said photo-responsive devices during a sample reading,

wherein said detecting head further includes a housing, movable member means, means mounting said movable member means on said housing for movement from a rest position to a position immediately over said viewing port, and a sheet of standard color material mounted on said movable member means for covering said viewing point when said member means is immediately over said viewing port,

wherein said housing has a light port for receiving light from said source and wherein said detecting means includes means for mounting said light source adjacent said light port, and

further including means for circulating air through said light source mounting means and past said housing for cooling.

57. A digital abridged spectrophotometer comprising:

a detecting head including a plurality of photoresponsive devices each mounted for receiving incident light over a different color band and providing an output signal varying as a function of received light,

control means for interrogating each of said photoresponsive devices including means for calibrating from signals derived by said photo-responsive devices viewing a standard sample prior to each sample reading,

means for providing a given time after calibration for sample reading,

and means for calculating the color values from the signals received from said photo-responsive devices during a sample reading,

wherein said detecting head further includes a housing, movable member means, means mounting said movable member means on said housing for movement from a rest position to a position immediately over said viewing port, and a sheet of standard color material mounted on said movable member means for covering said viewing port when said member means is immediately over said viewing port, and said housing is provided with cooling fins.

58. A digital abridged spectrophotometer comprising:

a detecting head including a plurality of photoresponsive devices each mounted for receiving incident light over a different color band and providing an output siganl varying as a function of received light,

control means for interrogating each of said photoresponsive devices including means for calibrating from signals derived by said photo-responsive devices viewing a standard sample prior to each sample reading,

means for providing a given time after calibration for sample reading, and

means for calculating the color values from the signals received from said photo-responsive devices during a sample reading,

wherein said detecting head further includes a housing, movable member means, means mounting said movable member means on said housing for movement from a rest position to a position immediately over said viewing port, and a sheet of standard color material mounted on said movable member means for covering said viewing port when said member means is immediately over said viewing port, and said housing includes means for mounting said housing on a table.

59. A digital abridged spectrophotometer comprising:

a detecting head including a plurality of photoresponsive devices each mounted for receiving incident light over a different color band and providing an output signal varying as a function of received light,

control means for interrogating each of said photoresponsive devices including means for calibrating from signals derived by said photo-responsive devices viewing a standard sample prior to each sample reading,

means for providing a given time after calibration for sample reading, and

means for calculating the color values from the signals received from said photo-responsive devices during a sample reading,

wherein said detecting head further includes a housing, movable member means, means mounting said movable member means on said housing for movement from a rest position to a position immediately over said viewing port, and a sheet of standard color material mounted on said movable member means for covering said viewing port when said member means is immediately over said viewing port, and

wherein said photo-responsive devices are photo-diodes.

60. A spectrophotometer as in claim 59 wherein said photo-diodes span the color band between 4000 to 7000 Angstroms with separations of 200 Angstroms.

61. A method of measuring the color of a sample comprising the steps of:

calibrating by color analyzing a standard sheet of material,

establishing a predetermined time window following said calibration,

calculating the color values for a sample only if the sample is analyzed within said time window.

62. A method as in claim 61 wherein said step of calibrating includes analyzing first and second sheets of material.

63. A method as in claim 61 further including displaying color values derived from the reflectance values.

64. A digital, abridged spectrophotometer comprising:

a detecting head having a housing providing a viewing port,

a plurality of photo-responsive devices each mounted in said housing for receiving incident light and being responsive to a different color band for providing an output signal varying as a function of the received light,

a sheet of standard color material,

means mounted on said housing for moving said standard sheet from a rest position to a position immediately over said port,

said moving means including a manually operated plunger member and means mounting said plunger member for movement from a rest position to a position immediately over said viewing port, and

digital computer means for interrogating each of said photo-responsive devices and determining the color values of material over said port.