Gloss Measurement Using Reflectance Spectra Difference
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Solution Overview
Problem
Current methods for determining the gloss of color standards, particularly for matt finishes, face challenges in unifying instrumental approaches between integrating sphere instruments and spectrophotometers, leading to sub-optimal predictions and the need for additional gloss measurement devices.
Innovation Solution
A method that involves experimentally determining reflection spectra with and without specular components, converting these data into gloss values using calibration curves, and applying these values to determine the necessary matting agent amount for achieving desired gloss levels in color standards, thereby integrating gloss measurement across different geometries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate gloss measurement devices are used for integrating sphere instruments and spectrophotometers, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent combines gloss measurement capability into the spectrophotometer by using the same optical sensor to detect both colorimetric data (L*, a*, b*) and gloss values (Y values). The integrating sphere instrument is modified to include a specular component exclusion capability, allowing it to function as both a colorimeter and gloss meter, thereby eliminating the need for separate gloss measurement devices while maintaining measurement precision
Solution Approach 2:
The spectrophotometer is designed with multi-functionality to perform both color measurement and gloss measurement using the same instrument and sensor system. By detecting reflectance data at multiple angles and processing it through specific algorithms (calculating Y values from L*, a*, b* data), the single device accomplishes what previously required multiple specialized instruments
2Measurement precision
If different measurement geometries are used for glossy and matt samples, then measurement precision is improved, but ease of operation deteriorates
Solution Approach 1:
The measurement system dynamically adapts its geometry based on the sample properties. The instrument automatically selects appropriate measurement angles (20°, 60°, or 85°) and specular component handling (included or excluded) based on the gloss level of the sample being measured. This dynamic adaptation allows a single instrument to optimally measure both glossy and matt samples without requiring manual geometry changes or operator expertise
Solution Approach 2:
The system changes measurement parameters (measurement angle, specular component exclusion) automatically based on the detected gloss level of the sample. By calculating Y values from colorimetric data and comparing against threshold values, the instrument dynamically adjusts its measurement geometry to match the appropriate scale (glossy or matt), eliminating the need for manual geometry selection
3Measurement precision
If multiple calibration scales are used for different gloss levels, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent introduces a new dimension of measurement by utilizing the L*, a*, b* colorimetric data to derive gloss information through Y value calculation. Instead of relying solely on traditional gloss meter readings, the system uses the spectral reflectance data from the integrating sphere to calculate gloss values, creating an additional measurement dimension that simplifies the calibration approach while maintaining precision across different gloss levels
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for accurate and automated determination of gloss values for color standards, enhancing the efficiency of color development processes and eliminating the need for separate gloss measurement devices, particularly for matt finishes.
Implementation Method 1
The first reflection spectrum (A1) includes a specular component, and the second reflection spectrum (A2) excludes the specular component
Implementation Method 2
the difference spectrum ΔR=R(SPIN)−R(SPEX) between specular included (SPIN) and specular excluded (SPEX) readings is a function of surface gloss
Data Source
AI summary
The invention relates to a method for determining the gloss of a colour standard comprising the following steps:A) experimentally determining reflection spectra R(exp) of the colour standard, comprising a first reflection spectrum and a second reflection spectrum, with an integrating sphere colour measurement instrument, wherein said first reflection spectrum is obtained at (A1) d/8°—geometry with the specular component included, and said second reflection spectrum is obtained at (A2) d/8°—geometry with the specular component excluded, andB) converting reflection spectra data of the experimentally determined reflection spectra R(exp) of the colour standard to gloss values by:B1) acquiring the difference reflection spectrum ΔR of the experimentally determined reflection spectrum R(exp) with the specular component included (A1) and the reflection spectrum R(exp) with the specular component excluded (A2), andB2) determining the gloss values corresponding to said difference reflection spectrum ΔR with the assistance of previously prepared calibration curves, representing the functional relationship between the difference reflection spectrum ΔR and the gloss values measured at one or more gloss angles.