Apparatus and method for measuring color

• US 7,113,283 B2
• Filed: 11/22/2002
• Issued: 09/26/2006
• Est. Priority Date: 01/02/1996
• Status: Expired due to Fees

• Current Assignee: RPX Corporation
• Original Assignee: JJL Technologies, L.L.C.
• Inventors: Jung, Wayne D., Jung, Russell W., Loudermilk, Alan R.
• Primary Examiner(s): EVANS, FANNIE L
• Application Number:
  US10/302,459
• Publication Number:
  US 20040012785A1
• Time in Patent Office: 1,404 Days
• Field of Search: 356/402, 356/405, 356/406, 356/407, 356/416, 356/419, 356/425
• US Class Current: 356/419
• CPC Class Codes: A61B 2560/0223 of calibration, e.g. protocols for calibrating sensors
• CPC Class Codes: A61B 2560/0233 Optical standards
• CPC Class Codes: A61C 19/10 Supports for artificial teeth for transport or for comparison of the colour
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/0208 using focussing or collimating elements, e.g. lenses or mirrors; performing aberration correction
• CPC Class Codes: G01J 3/0218 using optical fibers
• CPC Class Codes: G01J 3/0264 Electrical interface; User interface
• CPC Class Codes: G01J 3/0272 Handheld
• CPC Class Codes: G01J 3/0291 Housings; Spectrometer accessories; Spatial arrangement of elements, e.g. folded path arrangements
• CPC Class Codes: G01J 3/0297 Constructional arrangements for removing other types of optical noise or for performing calibration
• CPC Class Codes: G01J 3/04 Slit arrangements slit adjustment
• CPC Class Codes: G01J 3/10 Arrangements of light sources specially adapted for spectrometry or colorimetry
• CPC Class Codes: G01J 3/46 Measurement of colour; Colour measuring devices, e.g. colorimeters measuring colour temperature G01J5/60
• CPC Class Codes: G01J 3/50 using electric radiation detectors
• CPC Class Codes: G01J 3/508 measuring the colour of teeth
• 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
• CPC Class Codes: G01N 2021/6484 Optical fibres
• CPC Class Codes: G01N 21/251 Colorimeters; Construction thereof
• CPC Class Codes: G01N 21/474 : Details of optical heads therefor, e.g. using optical fibres
• CPC Class Codes: G01N 21/57 : Measuring gloss

Abstract

Color measuring systems and methods are disclosed. Perimeter receiver fiber optics are spaced apart from a central source fiber optic and receive light reflected from the surface of the object being measured. Light from the perimeter fiber optics pass to a variety of filters. The system utilizes the perimeter receiver fiber optics to determine information regarding the height and angle of the probe with respect to the object being measured. Under processor control, the color measurement may be made at a predetermined height and angle. Various color spectral photometer arrangements are disclosed. Translucency, fluorescence and/or surface texture data also may be obtained. Audio feedback may be provided to guide operator use of the system. The probe may have a removable or shielded tip for contamination prevention.

Claims

1. A color sensing apparatus for determining a color characteristic of received light comprising:

at least one light receiving input;

a plurality of filter elements;

a plurality of sensors, wherein at least certain of the sensors receive light from the at least one input via a respective one of the filter elements, wherein the sensors generate a plurality of signals having a frequency proportional to an intensity of light received by the at least one input;

wherein the color characteristic of the received light is determined based on the plurality of signals.

2. The apparatus of claim 1, wherein the filter elements comprise a gradient filter.

3. The apparatus of claim 1, wherein the filter elements comprise a plurality of bandpass filters.

4. The apparatus of claim 1, wherein the filter elements comprise a color filter array.

5. The apparatus of claim 1, wherein the sensors output digital signals.

6. The apparatus of claim 5, wherein the digital signals comprise TTL or CMOS compatible signals.

7. The apparatus of claim 6, wherein the digital signals are coupled to a microprocessor or logic circuitry without analog-to-digital conversion.

8. The apparatus of claim 1, wherein data from the sensors is coupled to a processing element, wherein the color characteristic is determined based on measuring a frequency of each of the plurality of signals.

9. The apparatus of claim 1, wherein data from the sensors is coupled to a processing element, wherein the color characteristic is determined based on measuring a period of each of the plurality of signals.

10. The apparatus of claim 1, wherein the apparatus comprises a spectrometer.

11. The apparatus of claim 1, wherein the apparatus comprises a colorimeter.

12. The apparatus of claim 1, wherein the at least one input receives light from one or more fiber optics.

13. The apparatus of claim 1, wherein the color characteristic is determined based on a calibration measurement.

14. The apparatus of claim 1, wherein the color characteristic is used to determine a closest color among a set of stored colors.

15. The apparatus of claim 1, wherein one or more sensors receive light that is not provided through a color filter element, wherein the one or more sensors that receive light that is not provided through a color filter element determine a gray level characteristic of the received light.

16. The apparatus of claim 1, wherein one or more sensors receive light that is not provided through a color filter element, wherein the one or more sensors that receive light that is not provided through a color filter element determine a physical position characteristic of a probe that couples light to the at least one input.

17. The apparatus of claim 1, wherein a processing element receives a plurality of inputs based on the plurality of signals, wherein the processing element determines a plurality of data values from the plurality of inputs at a known timing, and based on the plurality of data values from the plurality of inputs a frequency or period determination is made of each of the plurality of signals.

18. The apparatus of claim 1, wherein each of the sensors comprise an array of photodiodes.

19. The apparatus of claim 1, wherein IR light is reduced prior to being coupled to the plurality of sensors.

20. The apparatus of claim 1, wherein the IR light is reduced by removal of the IR light from a light source.

21. The apparatus of claim 1, wherein light is provided from at least one light source on a probe, wherein light is received by at least one light receiver on the probe and coupled to the at least one input;

wherein the at least one light receiver has a spacing from the at least one light source, wherein a first height is defined, wherein, when the probe is a distance from a surface of an abject under evaluation that is less than the first height, light that is reflected from the surface of the object is not received by the at least one light receiver.

22. The apparatus of claim 1, wherein the filter elements comprise a red filter, a green filter and a blue filter.

23. The apparatus of claim 22, wherein a red sensor is positioned to receive light via the red filter, a green sensor is positioned to receive light via the green filter, and a blue sensor is positioned to receive light via the blue filter.

24. The apparatus of claim 23, further comprising a broadband sensor, wherein light received by the broadband sensor does not pass through the red filter, the green filter or the blue filter.

25. The apparatus of claim 24, wherein the light received by the broadband sensor passes through a neutral density filter.

26. The apparatus of claim 24, wherein a gray level value is determined from data from the broadband sensor.

27. A color sensing apparatus for determining a color characteristic of received light comprising:

at least one light receiving input;

a plurality of filter elements;

a plurality of light-to-frequency converter sensors, wherein at least certain of the sensors receive light from the at least one input via a respective one of the filter elements, wherein the sensors generate a plurality of signals having a frequency that varies based on the light intensity received by the sensors;

wherein the color characteristic of the received light is determined based on the plurality of the signals.

28. The apparatus of claim 27, wherein each of the sensors comprises an array of photodiodes.

29. The apparatus of claim 27, wherein each of the signals comprises a digital signal.

30. The apparatus of claim 27, wherein each of the signals comprises a digital signal that is coupled to a processing element, wherein the processing element determines the frequency or period of each of the signals without analog-to-digital conversion.

31. A color sensing apparatus for determining a color characteristic of received light comprising:

at least one light receiving input;

at least a red filter element, a green filter element and a blue filter element;

a plurality of light-to-frequency converter sensors, wherein the sensors comprise at least a red sensor, a green sensor and a blue sensor that receive light from the at least one input via the red filter element, the green filter element and the blue filter element, respectively, wherein the sensors generate a plurality of signals having a frequency that varies based on an intensity of light received by the sensors;

wherein the color characteristic of the received light is determined based on the plurality of the signals.

32. The apparatus of claim 31, wherein each of the sensors comprises an array of photodiodes.

33. The apparatus of claim 31, wherein each of the signals comprises a digital signal.

34. The apparatus of claim 31, wherein each of the signals comprises a digital signal that is coupled to a processing element, wherein the processing element determines the frequency or period of each of the signals without analog-to-digital conversion.

35. A color sensing apparatus for determining a color characteristic of received light comprising:

at least one light receiving input;

at least a red filter element, a green filter element and a blue filter element;

a plurality of light-to-frequency converter sensors, wherein the sensors comprise at least a red sensor, a green sensor and a blue sensor that receive light from the at least one input via the red filter element, the green filter element and the blue filter element, respectively, wherein the sensors further comprise at least one broadband sensor that does not receive light via the red filter element, the green filter element or the blue filter element, wherein the sensors generate a plurality of signals having a frequency that varies based on an intensity of light received by the sensors;

wherein the color characteristic of the received light is determined based on the plurality of the signals.

36. The apparatus of claim 35, wherein each of the sensors comprises an array of photodiodes.

37. The apparatus of claim 35, wherein each of the signals comprises a digital signal.

38. The apparatus of claim 35, wherein each of the signals comprises a digital signal that is coupled to a processing element, wherein the processing element determines the frequency or period of each of the signals without analog-to-digital conversion.

39. The apparatus of claim 35, wherein the light received by the broadband sensor passes through a neutral density filter.

40. The apparatus of claim 35, wherein a gray level value is determined from data from the broadband sensor.