Apparatus and method for calibration in a spectrophotometer

A compensation method adapted for use in color measuring apparatus for measuring color characteristics of actual object samples under test, said method comprising the steps of:

• employing a reference sample and projecting light toward said reference sample through use of a light source means;
• performing a plurality of measurements of said reference sample, with said measurements providing measured color characteristic values of said reference sample for a series of spectral segments across a light spectrum;
• performing a plurality of side sensor measurements, with said side sensor measurements providing measured light source intensity values indicative of the intensity of said light source means;
• determining at least one temperature value of said light source means or area adjacent said light source means during performance of said plurality of measurements of said reference sample;
• determining a temperature coefficient for each segment of said series of spectral segments;
• determining at least one temperature value of said light source means or area adjacent said light source means during performance of measurements of color characteristic values of said actual object samples under test;
• and
• compensating measurements of color characteristic values for a particular segment of said actual object samples under test as a function at least in part of said temperature coefficient for said particular segment, said at least one temperature value obtained during measurements of color characteristic values of said actual object samples under test, and at least one temperature value obtained during performance of said plurality of measurements of said reference sample.

A compensation method adapted for use in color measuring apparatus for measuring color characteristics of actual object samples under test, said method comprising the steps of:

• employing a reference sample and projecting light toward said reference sample through use of a light source means;
• performing a plurality of measurements of said reference sample, with said measurements providing measured color characteristic values of said reference sample for a series of spectral segments across a light spectrum;
• performing a plurality of side sensor measurements, with said side sensor measurements providing measured light source intensity values indicative of the intensity of said light source means;
• determining at least one temperature value of said light source means or area adjacent said light source means during performance of said plurality of measurements of said reference sample;
• determining a temperature coefficient for means employed for performing said plurality of side sensor measurements;
• determining at least one temperature value of said light source means or area adjacent said light source means during performance of measurements of color characteristic values of said actual object samples under test;
• and
• compensating measurements of color characteristic values of said actual object samples under test as a function at least in part of said temperature coefficient, said at least one temperature value obtained during performance of said plurality of measurements of said reference sample, and said at least one temperature value obtained during performance of said measurements of color characteristic values of said actual object samples under test.

A color measuring apparatus for use in measuring color characteristics of actual object samples under test and for compensating measurements of said color characteristics through the use of a reference sample, said apparatus comprising:

• light source means for projecting light toward said reference sample;
• color characteristic measuring means for performing a first plurality of measurements of said reference sample, and for generating signals representative of measured color characteristic values of said reference sample for each of a series of spectral segments across a light spectrum and wherein said first plurality of measurements of said reference sample includes a second plurality of measurements made over time for each spectral segment of said series of spectral segments;
• means for performing a plurality of side sensor measurements and generating signals representative of measured light source intensity values indicative of the intensity of said light source means, and with said side sensor measurements being performed in the absence of complete spectral equivalence between said side sensor measurements and said first plurality of measurements of said reference sample;
• a processor responsive to said signals representative of said measured color characteristic values and responsive to said signals representative of said measured light source intensity values for determining a filter compensation coefficient for each of said segments as a function of a ratio of at least two of said measured color characteristic values of said reference sample for the corresponding segment and as a function of a ratio of at least two of said measured light source intensity values;
• and
• said processor comprising means for compensating measurements of color characteristic values of said actual object samples under test for a particular segment, as a function at least in part of said filter compensation coefficient for said particular segment.

A color measuring apparatus for use in measuring color characteristics of actual object samples under test and for compensating measurements of said color characteristics through the use of a reference sample, said apparatus comprising:

• light source means for projecting light toward said reference sample;
• color characteristic measuring means for performing a plurality of measurement of said reference sample, and for generating signals representative of measured color characteristic values of said reference sample for a series of spectral segments across a light spectrum;
• means for performing a plurality of side sensor measurements and generating signals representative of measured light source intensity values indicative of the intensity of said light source means;
• means for determining at least one temperature value of said light source means or area adjacent said light source means during performance of said plurality of measurements of said reference sample;
• means for determining a temperature coefficient for each segment of said series of spectral segments;
• means for determining at least one temperature value of said light source means or area adjacent said light source means during performance of measurements of color characteristic values of said actual object samples under test;
• and
• means for compensating measurements of color characteristic values for a particular segment of said actual object samples under test as a function at least in part of said temperature coefficient for said particular segment, said at least one temperature value obtained during measurements of color characteristic values of said actual object samples under test, and at least one temperature value obtained during performance of said plurality of measurements of said reference sample.

A color measuring apparatus for measuring color characteristics of actual object samples under test and for compensating measurements of said color characteristics through the use of a reference sample, said apparatus comprising:

• light source means for projecting light toward said reference sample;
• means for performing a plurality of measurements of said reference sample, and for generating signals representative of measured color characteristic values of said reference sample for a series of spectral segments across a light spectrum;
• means for performing a plurality of side sensor measurements and for generating signals representative of measured light source intensity values indicative of the intensity of said light source means;
• means for determining at least one temperature value of said light source means or area adjacent said light source means during performance of said plurality of measurements of said reference sample;
• means for determining a temperature coefficient for said means for performing said plurality of side sensor measurements;
• means for determining at least one temperature value of said light source means or area adjacent said light source means during performance of measurements of color characteristic values of said actual object samples under test;
• and
• means for compensating measurements of color characteristic values of said actual object samples under test as a function at least in part of said temperature coefficient, said at least one temperature value obtained during performance of said plurality of measurements of said reference sample, and said at least one temperature value obtained during performance of said measurements of color characteristic values of said actual object samples under test.