Color sensor employing optical fiber bundles with varied diameters

• US 5,229,841 A
• Filed: 07/10/1991
• Issued: 07/20/1993
• Est. Priority Date: 07/10/1991
• Status: Expired due to Term

• Current Assignee: Camp Inc.
• Original Assignee: Eaton Corp. (Wisconsin) (Eaton Corporation PLC.)
• Inventors: McClanahan, David L., Taranowski, Michael G.
• Primary Examiner(s): Evans, F. L.
• Assistant Examiner(s): HANTIS, KAREN
• Application Number:
  US07/727,730
• Time in Patent Office: 741 Days
• Field of Search: 356/402-411, 356/326, 356/328, 385/12, 362/32, 362/231, 362/800
• US Class Current: 356/406
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/0218 using optical fibers
• 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
• CPC Class Codes: G01N 2201/084 Fibres for remote transmission

Abstract

A device (1) for photoelectrically sensing the color of an object (18) includes a plurality of light emitting diodes (4, 6, 8) emitting light in a narrow range of wavelengths and where the light is transmitted through a corresponding fiber optic bundle (10, 12, 14) with a diameter in proportion to the transmission loss of the bundle and in inverse proportion to the emitted light energy of the corresponding light emitting diode and in proportion to the spectral response of a receiving photodiode (24). A receiving section (22) utilizes a PIN type photodiode (24) with an input section (40) that matches the shape of a receiving optical fiber bundle termination (42) where the photodiode (24) converts the reflected light from the object (18) into electrical signals which are then processed by a microprocessor (28) which also controls the activation of the light emitting diodes (4, 6, 8) and outputs a signal indicative of the color of the object (18).

Claims

1. A color sensing system for the recognition of a colored object comprising:

a plurality of electronic light emitters, each emitting light in a predetermined narrow-band range of wavelengths;

a receiving randomized optical fiber bundle having a first and second end for conducting a reflected light from a colored object;

said first end directed at said colored object;

an electronic light receiver means coupled to said second end of said receiving randomized optical fiber bundle for converting said reflected light into an electrical signal; and

a plurality of light transmitting randomized optical fiber bundles, each bundle coupled to a respective one of said light emitters and having a cross-sectional area approximately inversely proportional to the product of a light power level of said respective light emitter multiplied by the spectral response of said electronic light receiver, said emitting light conducted through said transmitting randomized optical fiber bundle and illuminating said colored object causing light to be reflected therefrom where said transmitting randomized optical fiber bundle is substantially constant in effective cross-sectional area over its length; and

an electronic processing means connected to said electronic light receiver means for making a color recognition determination based on said electrical signal.

2. The color sensing system according to claim 1, wherein said electronic light emitters are light emitting diodes.

3. The color sensing system according to claim 2, wherein said diodes are selected having one emitting light with a peak wavelength of approximately 605 nm, one emitting light with a peak wavelength of approximately 555 nm, and one emitting light with a peak wavelength of approximately 470 nm.

4. The color, sensing system according to claim 1, wherein said transmitting randomized optical fiber bundles have cross-sectional diameters approximately in the ratio of 1:

1.5;

1.8 respectively connected to an orange, green and blue electronic light emitter of the type known as light emitting diodes.

5. The color sensing system according to claim 1, wherein said electronic light receiver means is of the type using a PIN photodiode, said receiving randomized optical fiber bundle having said second end shaped to match an input receptacle to said PIN photodiode.

6. The color sensing system according to claim 1, wherein an optical lens is placed between said colored object and said first end.

7. The color sensing system according to claim 1, wherein said receiving randomized optical fiber bundle is joined to and randomized with said light transmitting randomized optical fiber bundles.

8. The color sensing system according to claim 1, wherein said transmitting randomized optical fiber bundles and said receiving randomized optical fiber bundles are formed of a plurality of randomized single optical fiber strands, said transmitting randomized optical fiber bundles and said receiving randomized optical fiber bundles are separate and then joined by intermixing and randomizing said fiber strands forming a single optical fiber bundle having a substantially constant cross-sectional area and having an end directed at said colored object.

9. A color sensing system for the recognition of colored objects, comprising:

at least two light transmitters each emitting light in a predetermined narrow-based range of wavelengths;

light receiving means for receiving reflected light from the colored object and converting said reflected light into individual electrical signals;

at least two transmitting randomized optical fiber bundles each having a first end converted to a respective light transmitter and a second end directed at the colored object said bundles conducting said emitting light from said first end to said second end and emerging from said second end to illuminate the colored object where each of the said transmitting randomized optical fiber bundles has an approximately constant diameter approximately in inverse proportion to the light output power of said light transmitter and where each of said transmitting randomized optical fiber bundles has an approximately constant effective cross-sectional area;

a receiving randomized optical fiber bundle having a first end directed at the object and a second end directed as said light receiving means; and

signal processing means coupled to said individual electrical signals for generating an output signal representative of the colored surface of said object.

10. The color sensing system according to claim 9, wherein said electronic light transmitters are light emitting diodes, said diodes selected to transmit light in a narrow-band range of wavelengths.

11. The color sensing system according to claim 9, wherein said light receiver comprises a light sensitive semiconductor where said second end of said receiving optical fiber bundle is shaped to match the shape of an input section of said light sensitive semiconductor.

12. The color sensing system according to claim 11, wherein said light sensitive semiconductor is a PIN photodiode.

13. The color sensing system according to claim 9, wherein said second ends of said transmitting randomized optical fiber bundles and said second end of said receiving randomized optical bundle are comprised of a plurality of optical fibers which are randomized in a sensing end.

14. The color sensing system according to claim 9, wherein said cross-sectional area is further sized to offset a difference is light transmission loss of said transmitting randomized optical fiber bundle.

15. The color sensing system according to claim 9, wherein an optical lens is interposed between said first end of said receiving randomized optical fiber bundle and the object.

16. The color sensing system according to claim 9, wherein said first end of said receiving randomized optical fiber bundle is grouped in a package with said second end of said transmitting randomized optical fiber bundles and a reflective surface is placed opposite said package with the colored object therebetween, said reflective surface positioned to reflect a portion of said emitting light passing through said colored object back through said colored object and into said first end of said receiving randomized optical fiber bundle.

17. The color sensing system according to claim 9, wherein said second ends of said transmitting randomized optical fiber bundles are positioned opposing said first end of said receiving randomized optical fiber bundle, a colored object being placed therebetween.

18. The color sensing system according to claim 9, wherein said transmitting randomized fiber bundles have a cross-sectional area in proportion to the spectral response of said light receiving means.