Apparatus and method for measuring color

• US 8,159,666 B2
• Filed: 07/14/2008
• Issued: 04/17/2012
• Est. Priority Date: 01/02/1996
• Status: Expired due to Fees

• Current Assignee: RPX Corporation
• Original Assignee: JJL Technologies, L.L.C.
• Inventors: Jung, Russell W., Loudermilk, Alan R., Jung, Wayne D.
• Primary Examiner(s): Evans, Fannie L.
• Application Number:
  US12/218,339
• Publication Number:
  US 20090306926A1
• Time in Patent Office: 1,373 Days
• Field of Search: None
• US Class Current: 356/326
• 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

Methods in a spectral measurement apparatus are disclosed. Light is received with a plurality of sensors. Each sensor generates an output signal having a frequency proportional to an intensity of light received by the sensor. First, second and third signals are generated each having a frequency proportional to an intensity of light received by a sensor of a wavelength or spectral band. A spectral characteristic of the received light is determined based on at least the first, second and third signals, which are are coupled to a processing element and input in parallel. The spectral characteristic is determined based on measuring a frequency or period of the at least first, second and third signals. Spectral data based on the determined spectral characteristic is generated by the processing element and displayed on a display device for perception by a viewer or transmitted to a data interface for transmission to an electronic device external to the spectral measurement apparatus.

Claims

1. A method in a spectral measurement apparatus comprising the steps of:

receiving light with a plurality of sensors, wherein each sensor generates an output signal having a frequency proportional to an intensity of light received by the sensor;

generating at least a first signal having a frequency proportional to an intensity of light received by a first sensor of a first wavelength or spectral band;

generating at least a second signal having a frequency proportional to an intensity of light received by a second sensor of a second wavelength or spectral band; and

generating at least a third signal having a frequency proportional to an intensity of light received by a third sensor of a third wavelength or spectral band;

wherein a spectral characteristic of the received light is determined based on at least the first, second and third signals;

wherein the at least first, second and third signals are coupled to a processing element and input to the processing element in parallel, wherein the spectral characteristic is determined based on measuring a frequency or period of the at least first, second and third signals;

wherein spectral data based on the determined spectral characteristic is generated by the processing element and displayed on a display device for perception by a viewer or transmitted to a data interface for transmission to an electronic device external to the spectral measurement apparatus.

2. The method of claim 1, wherein the sensors each output one or more digital signals.

3. The method of claim 2, wherein the one or more digital signals comprise TTL or CMOS compatible signals.

4. The method of claim 3, wherein the one or more digital signals are coupled to a microprocessor or logic circuitry without analog-to-digital conversion.

5. The method of claim 1, wherein the spectral characteristic is determined based on measuring a frequency of the at least first, second and third signals.

6. The method of claim 1, wherein the spectral characteristic is determined based on measuring a period of the at least first, second and third signals.

7. The method of claim 1, wherein the spectral measurement apparatus comprises a spectrometer.

8. The method of claim 1, wherein the spectral measurement apparatus comprises a colorimeter.

9. The method of claim 1, wherein light is received from an object or material via one or more fiber optics.

10. The method of claim 1, wherein the spectral characteristic is determined based on a calibration measurement.

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

12. The method of claim 1, wherein the light is generated via a broadband light source.

13. The method of claim 1, wherein the light is generated via a plurality of light sources of different colors.

14. The method of claim 1, wherein the processing element determines a plurality of data values from the first, second and third signals at a predetermined timing, wherein, based on the plurality of data values determined from the first, second and third signals, a frequency or period determination is made for each of the first, second and third signals.

15. The method of claim 1, wherein the sensors each comprise an array of photodiodes.

16. The method of claim 1, wherein the spectral characteristic is used to determine one or more closest matches to a plurality of stored colors or shades, wherein the stored colors or shades comprise shades of one or more dental shade guide systems.

17. The method of claim 1, wherein the processing element is coupled to a light source, wherein the light source is controlled based on a signal from the processing element.

18. A method in a spectral measurement apparatus for determining a spectral characteristic of received light comprising the steps of:

generating and supplying light of a plurality of wavelengths or spectral bands;

receiving light with a plurality of sensors, wherein each sensor generates an output signal having a frequency proportional to an intensity of light received by the sensor;

generating at least a first signal having a frequency proportional to an intensity of light received by a first sensor of a first wavelength or spectral band;

generating at least a second signal having a frequency proportional to an intensity of light received by a second sensor of a second wavelength or spectral band; and

generating at least a third signal having a frequency proportional to an intensity of light received by a third sensor of a third wavelength or spectral band;

wherein a spectral characteristic of the received light is determined based on at least the first, second and third signals;

wherein the at least first, second and third signals are coupled to a processing element and input to the processing element in parallel, wherein the spectral characteristic is determined based on measuring a frequency or period of the at least first, second and third signals;

wherein spectral data based on the determined spectral characteristic is generated by the processing element and displayed on a display device for perception by a viewer or transmitted to a data interface for transmission to an electronic device external to the spectral measurement apparatus.

19. The method of claim 18, wherein the spectral measurement apparatus comprises a spectrometer.

20. The method of claim 18, wherein the processing element is coupled to a light source, wherein the light source is controlled based on a signal from the processing element.