Color sensor

• US 6,147,761 A
• Filed: 04/14/1998
• Issued: 11/14/2000
• Est. Priority Date: 09/12/1996
• Status: Expired due to Term

• Current Assignee: Color Savvy Systems Ltd.
• Original Assignee: Color Savvy Systems Ltd.
• Inventors: Duke, Ronald J., Walowit, Eric, Sam, Long B., Iseli, Victor L.
• Primary Examiner(s): Font, Frank G.
• Assistant Examiner(s): STAFIRA, MICHAEL PATRICK
• Application Number:
  US09/059,889
• Time in Patent Office: 945 Days
• Field of Search: 356/326, 356/320, 356/330-334, 356/445-448, 356/237.1, 356/402, 356/406-408, 356/420, 356/425, 356/430, 356/431, 250/226
• US Class Current: 356/425
• CPC Class Codes: G01J 2003/2866 Markers; Calibrating of scan
• CPC Class Codes: G01J 3/0251 Colorimeters making use of an integrating sphere
• CPC Class Codes: G01J 3/0272 Handheld
• CPC Class Codes: G01J 3/46 Measurement of colour; Colour measuring devices, e.g. colorimeters measuring colour temperature G01J5/60
• CPC Class Codes: G01J 3/463 Colour matching
• CPC Class Codes: G01J 3/465 taking into account the colour perception of the eye; using tristimulus detection
• CPC Class Codes: G01J 3/50 using electric radiation detectors
• CPC Class Codes: G01J 3/501 Colorimeters using spectrally-selective light sources, e.g. LEDs
• CPC Class Codes: G01J 3/524 Calibration of colorimeters

Abstract

A sensor for measuring reflective, transmissive, or self-luminous samples, comprises a plurality of light sources, where each of the light sources emit light of a substantially different wavelength band spaced in the visible spectrum; a reference channel photodetector; a sample channel photodetector; an optical cap adapted to direct a first portion of the light emitted by each of the light sources to the reference channel photodetector, a reflector cone for directing a second portion of the light emitted by each of the light sources to the sample; and a receptor piece for directing the diffuse portion of the light reflected from the sample to the sample channel photodetector. Preferably, the reference channel and sample channel photodetectors are identical devices and are mounted back-to-back to share environmental characteristics, and in turn, minimize the variation between their respective responses. The sensor is preferably incorporated into a hand-held "mouse" device, which includes an area on its top surface for seating an index finger of the human hand. Positioned within this area is a pressure-activated switch that is operatively coupled to the sensor circuitry for performing the various readings. And the sensor is preferably mounted into the mouse device such that the focal aperture of the downward pointing reflector cone is in axial alignment with the pressure-activated switch. Accordingly, a user will be able to use the mouse to "point" with his or her index finger to an area of the sample surface, and will then simply press the switch using the same index finger.

Claims

1. A sensor for sensing reflective, spectrophotometric, densitometric, colorimetric, self-luminous or radiometric characteristics of a sample, comprising:

a base having a lower surface;

a plurality of light sources respectively emitting light of a substantially different wavelength band, mounted to said base such that a first portion of light emitted by said light sources transmits below said lower surface of said base;

a sample photodetector; and

a first optical assembly, mounted to said lower surface of said base, said first optical assembly being configured to direct said first portion of the light to the sample while excluding direct transmission of said first portion of light to said sample photodetector and being further configured to direct a portion of light reflected from the sample to said sample photodetector;

said first optical assembly includes an annular collar mounted to said lower surface of said base and positioned over said plurality of light sources and over said sample photodetector, said collar including a plurality of emitter apertures extending axially therethrough, each emitter aperture being provided for a corresponding one of said light sources, and said collar includes a receiver aperture extending axially through said collar so as to provide optical communication between the sample and said sample photodetector;

said emitter apertures being arranged about said sample photodetector;

said first optical assembly further including a reflector cone, said reflector cone including a central axis, a hollow cavity, a tip, and a focal aperture in said tip, said focal aperture providing optical communication into said hollow cavity;

said reflector cone extending from a lower surface of said collar;

said focal aperture and said receiver aperture being coaxially aligned on said central axis;

each of said emitter apertures including an emitter axis;

said reflector cone including a frustoconically shaped reflective inner surface, coaxially aligned with said central axis and positioned to intersect with each of said emitter axes; and

said reflective inner surface of said hollow cavity being angled inwardly toward said central axis at an angle so as to direct said first portion of light emitted by said light sources towards said focal aperture at substantially a 45°

angle with respect to said central axis;

whereby, when said focal aperture is placed on a sample surface said first portion of light emitted by said light sources is reflects off of said inner surface of said hollow cavity, and is directed toward the sample surface at substantially a 45°

angle, and reflects off of the sample surface at substantially a 45°

angle, and said sample photodetector receives a diffuse component of said light reflected off of the sample surface.

2. The sensor of claim 1, wherein said light sources are light emitting diodes, and said light emitting diodes are encapsulated so as to provide a lens integral with said light emitting diodes.

3. The sensor of claim 1, wherein said collar is configured to thermally isolate said light sources from said sample photodetector.

4. The sensor of claim 1, further comprising an optical filter mounted within said receiver aperture for excluding a predetermined component of light entering said receiver aperture.

5. The sensor of claim 1, wherein said base is a printed circuit board, said light sources are light emitting diodes, and said light emitting diodes and said sample photodetector are mounted to said printed circuit board.

6. A sensor for sensing reflective, spectrophotometric, densitometric, calorimetric, self-luminous or radiometric characteristics of a sample, comprising:

a base having a lower surface;

a plurality of light sources respectively emitting light of a substantially different wavelength band, mounted to said base such that a first portion of light emitted by said light sources transmits below said lower surface of said base;

a sample photodetector; and

a first optical assembly, mounted to said lower surface of said base, said first optical assembly being configured to direct said first portion of the light to the sample while excluding direct transmission of said first portion of light to said sample photodetector and being further configured to direct a portion of light reflected from the sample to said sample photodetector;

said first optical assembly includes an annular collar mounted to said lower surface of said base and positioned over said plurality of light sources and over said sample photodetector, said collar including a plurality of emitter apertures extending axially therethrough, each emitter aperture being provided for a corresponding one of said light sources, and said collar includes a receiver aperture extending axially through said collar so as to provide optical communication between the sample and said sample photodetector;

said emitter apertures including an upper cylindrical channel and a lower cylindrical channel coaxially aligned with one another and said corresponding emitter axis, the lower cylindrical channel having a diameter smaller than the upper cylindrical channel so as to collimate said first portion of light emitted by said light sources.

7. A sensor for sensing reflective, spectrophotometric, densitometric, calorimetric, self-luminous or radiometric characteristics of a sample, comprising:

a base having a lower surface;

a plurality of light sources respectively emitting light of a substantially different wavelength band, mounted to said base such that a first portion of light emitted by said light sources transmits below said lower surface of said base;

a sample photodetector; and

a first optical assembly, mounted to said lower surface of said base, said first optical assembly being configured to direct said first portion of the light to the sample while excluding direct transmission of said first portion of light to said sample photodetector and being further configured to direct a portion of light reflected from the sample to said sample photodetector;

said first optical assembly includes an annular collar mounted to said lower surface of said base and positioned over said plurality of light sources and over said sample photodetector, said collar including a plurality of emitter apertures extending axially therethrough, each emitter aperture being provided for a corresponding one of said light sources, and said collar includes a receiver aperture extending axially through said collar so as to provide optical communication between the sample and said sample photodetector;

the sensor further comprising a reference photodetector; and

a second optical assembly configured to direct a second portion of light emitted by said light sources to said reference photodetector.

8. The sensor of claim 7, wherein:

said reference photodetector includes a reference output channel;

said sample photodetector includes a sample output channel; and

the sensor further comprises a processing circuit coupled to said reference output channel and to said sample output channel, said processing circuit being configured to generate reflective, spectrophotometric, densitometric or colorimetric data pertaining said sample according, at least in part, to a ratio of data received from said reference channel versus data received from said sample channel.

9. The sensor of claim 8, wherein said processing circuit includes an adjustable current source for providing controlled power to each of said light sources.

10. The sensor of claim 9, wherein said processing circuit includes a current detector for monitoring current to said light sources, said current detector generating a current signal used by said processing circuit in controlling said adjustable current source.

11. The sensor of claim 10, wherein said current signal is used by said processing circuit to correct said reference channel output response against an expected output response.

12. The sensor of claim 8, wherein said processing circuit includes a switch component, coupled to said plurality of light sources, allowing said processing circuit to activate each of said light sources separately, or in combination, in a predetermined sequence.

13. The sensor of claim 8, wherein said processing circuit is a successive approximation circuit.

14. A sensor for sensing reflective, spectrophotometric, densitometric, colorimetric, self-luminous or radiometric characteristics of a sample, comprising:

a base having a lower surface;

a plurality of light sources respectively emitting light of a substantially different wavelength band, mounted to said base such that a first portion of light emitted by said light sources transmits below said lower surface of said base;

a sample photodetector; and

a first optical assembly, mounted to said lower surface of said base, said first optical assembly being configured to direct said first portion of the light to the sample while excluding direct transmission of said first portion of light to said sample photodetector and being further configured to direct a portion of light reflected from the sample to said sample photodetector;

said first optical assembly includes an annular collar having a central axis mounted to said lower surface of said base and positioned over said plurality of light sources and over said sample photodetector, said collar including a plurality of emitter apertures extending axially therethrough, each emitter aperture being provided for a corresponding one of said light sources, and said collar includes a receiver aperture extending axially through said collar so as to provide optical communication between the sample and said sample photodetector;

the sensor further comprising a second photodetector, positioned at substantially a 45°

angle with respect to said central axis and diametrically aligned with at least one of said light sources to thereby receive a specular component of said light reflected from the sample, whereby said sensor can be used to measure surface gloss of the sample.

15. A sensor for sensing reflective, spectrophotometric, densitometric, colorimetric, self-luminous or radiometric characteristics of a sample, comprising:

a base having a lower surface;

a plurality of light sources respectively emitting light of a substantially different wavelength band, mounted to said base such that a first portion of light emitted by said light sources transmits below said lower surface of said base;

a sample photodetector; and

a first optical assembly, mounted to said lower surface of said base, said first optical assembly being configured to direct said first portion of the light to the sample while excluding direct transmission of said first portion of light to said sample photodetector and being further configured to direct a portion of light reflected from the sample to said sample photodetector;

said first optical assembly includes an annular collar mounted to said lower surface of said base and positioned over said plurality of light sources and over said sample photodetector, said collar including a plurality of emitter apertures extending axially therethrough, each emitter aperture being provided for a corresponding one of said light sources, and said collar includes a receiver aperture extending axially through said collar so as to provide optical communication between the sample and said sample photodetector;

said sample photodetector including a sample output channel;

the sensor further comprising a processing circuit coupled to said sample output channel, said processing circuit being configured to generate reflective, densitometric, spectrophotometric or calorimetric, self-luminous or radiometric data of said sample based upon data received from said sample channel; and

said processing circuit including a current detector for monitoring current to said light sources, said current detector generating a current signal used by said processing circuit to correct said reflective, densitometric, spectrophotometric or colorimetric data.

16. A sensor for detecting colorimetric, reflective, densitometric or spectrophotometric, self-luminous or radiometrc characteristics of a sample, comprising:

a plurality of light emitting diodes for emitting light of substantially different wavelength bands spaced in a predefined spectrum;

a base having top surface and a bottom surface, a plurality of emitter apertures extending completely therethrough from said top surface to said bottom surface;

an optical cap having a substantially non-absorbing interior integrating surface mounted over said top surface of said base;

a reference photodetector mounted to said top surface of said base;

a sample photodetector mounted to said bottom surface of said base;

said light emitting diodes being mounted within said cap and adjacent to or in said emitter apertures such that a first portion of light emitted by said light emitting diodes is transmitted through said emitter apertures to a sample and reflected from said sample to said sample photodetector, and such that a second portion of light emitted by said light emitting diodes is transmitted to said integrating surface and directly or indirectly reflected from said integrating surface to said reference photodetector.

17. The sensor of claim 16, wherein said light emitting diodes are encapsulated so as to provide a lens integral with said light emitting diodes.

18. The sensor of claim 16, wherein said reference photodetector and said sample photodetector are mounted in close proximity to one another so as to share environmental characteristics.

19. The sensor of claim 18, further comprising a thermally conductive material mounted in said base, between said sample photodetector and said reference photodetector.

20. The sensor of claim 19, herein said thermally conductive material is also electrically conductive.

21. The sensor of claim 16, further comprising a reflecting surface extending below said bottom surface of said base and in alignment with said apertures, said reflector surface being angled so as to reflect said first portion of light emitted by said light emitting diodes to said sample at substantially a 45°

angle.

22. The sensor of claim 16, wherein said emitter apertures include a cylindrical channel axially aligned with said corresponding emitter axis so as to collimate said portion of light emitted by said light emitting diodes.

23. The sensor of claim 16, further comprising a programmable light emitting diode power source for activating said light emitting diodes or combinations of said light emitting diodes in a predetermined sequence.

24. The sensor of claim 16, wherein said predefined spectrum is a spectrum of visible light.

25. The sensor of claim 16, wherein said predefined spectrum is a spectrum of infrared light.

26. A sensor for sensing colorimetric, reflective, densitometric or spectrophotometric characteristics of a sample, comprising:

a printed circuit board;

a plurality of light sources, each of said light sources respectively emitting light of a substantially different wavelength band;

a reference photodetector surface mounted to a surface of said printed circuit board;

a sample photodetector surface mounted to an opposite surface of said printed circuit board;

a first optical element adapted to direct a first portion of the light emitted by each of said light sources to said reference photodetector;

a second optical element adapted to direct a second portion of the light emitted by each of said light sources to the sample; and

a third optical element adapted to direct a portion of light reflected off of the sample to said sample photodetector.

27. A sensor for detecting calorimetric, reflective, densitometric or spectrophotometric, self-luminous or radiometric characteristics of a sample, comprising:

a plurality of light sources for emitting light of substantially different wavelength bands spaced in a predefined spectrum;

a base having top surface and a bottom surface, a plurality of emitter apertures extending completely therethrough from said top surface to said bottom surface;

a substantially non-absorbing interior integrating surface positioned over said top surface of said base;

a reference photodetector mounted to said top surface of said base;

a sample photodetector mounted to said bottom surface of said base;

said light sources being positioned adjacent to or in said emitter apertures such that a first portion of light emitted by said light sources is transmitted to a sample and reflected from said sample to said sample photodetector, and such that a second portion of light emitted by said light sources is transmitted to said integrating surface and directly or indirectly reflected from said integrating surface to said reference photodetector.