What is the cause of the colorimeter test error?
The colorimeter test results why there will be errors? Many users operate the colorimeter using the wrong method or did not choose the correct colorimeter products. This is why the test results are not accurate enough, the following analysis of the main reasons for the existence of errors in the colorimeter test.
The difference in the working principle of different colorimeter
Colorimeter is developed after the principle of human eye color detection equipment, it is composed of lighting system, detection system and data system three parts, which lighting, detection part can be divided into “0/45”, “45/0”, “d/0”, “d/0”, “d/0”, “d/0”, “d/0”, “d/0”, “d/0”, “d/0”, “d/0”. “d/0”, “d/8” and other measurement and observation methods. “0/45” and “45/0” are designed to simulate the observation angle of the human eye, the light source from 45 ° angle into the 0 ° angle for measurement, this measurement method is suitable for flat objects. For irregular surfaces, it is difficult to measure accurately. The “d/8” integrating sphere colorimeter uses a ball with a white interior to diffuse illuminate the sample and measure at an angle of 8°. The data system can directly display the color parameters of the object through numerical values and translate them into our easily understood L*, a*, b* according to the three stimulus value chromaticity coordinates specified by CIE. With these three values, the color of the object is accurately expressed.
Choose different colorimeter; there are different working principles, the measurement method is also different, the final color difference value results will be different. It should be especially noted that even if the same model of colorimeter equipment, measuring the same object color difference results may have deviations. Different color difference meter standard version is different, generally speaking, the same model color difference meter normal stage difference will be controlled within ΔE*ab 0.2. Two-color difference meter parameters are not consistent, which may also lead to greater measurement value error, such as the choice of the light source, angle.
Light source parameters
Many color difference meters will be configured with a variety of internal light sources, referring to the CIE regulations to simulate a variety of artificial light sources under the ambient light, such as the standard light source D65, A light source, etc., the relative spectral distribution is close to the CIE standard illumination body relative spectral distribution. In terms of colorimeter measurement values, choosing the appropriate detection light source, for the accuracy of the measurement results is also critical, if you choose a different light source, then there will be differences in the measurement results
Field of view angle
When we choose a colorimeter, there is such a parameter: the observer angle of 2 ° / 10 °. Here the observer angle refers to the measurement of the field of view angle. The formation of the field of view angle is related to the structure of the human eye, in order to more accurately simulate the process of human eye observation, choose a different field of view angle, the color difference results will also be different. However, in the relevant literature analysis, in A light source, 2 ° and 10 ° measurement results do not differ significantly.
The temperature when measuring
Chromatic aberration meter detection is the temperature change, which will also affect the accuracy of the measurement results. Temperature changes therefore the color change, which is a physical phenomenon, different materials whose thermal discoloration is different, if it is some temperature-sensitive materials, then if the temperature is inconsistent when measuring, the results detected by the color difference meter will be different.
In the use of a colorimeter, improper operation, will also lead to inaccurate measurement results. For example, the color difference meter power supply voltage is unstable, the light source luminescence is not stable; the calibration plate can not be successfully calibrated; the measurement sample measurement area is too small, less with the instrument lens area, etc. Users can be based on the colorimeter operation specification requirements, the correct completion of the color measurement steps.
Color difference test dark color is not accurate why?.
Generally speaking, black and dark blue is the color management link is difficult to control the color because the black for visible light reflection is very little, the conventional colorimeter products are through the sample surface to measure the reflected light, therefore, the dark color compared to medium or light color more difficult to measure. To determine if the colors match, the manufacturer measures the target color and the resulting sample and then compares the spectral data. The color tolerance limit, also known as the allowable color difference, provides a guide to the size of acceptable color difference. This color difference is referred to as ΔE.
What should I do if my colorimeter test deviates too much?
In the process of colorimeter measurement, if the measurement result is very abnormal, the user needs to analyze the cause of the excessive deviation, and the method of calibration is as follows.
1, the colorimeter for correction, if the colorimeter calibration is not accurate, then the measurement results will have a large deviation.
2, check whether the instrument’s power supply voltage is normal, if the instrument’s power supply is insufficient, then the measurement can not ensure the normal work of the instrument, the measurement results will have a large deviation
3, check whether the measurement sample is flat, if the measurement port and the measurement surface contact is not close, it will lead to the interference of external light so that the wrong colorimetric calibration results.
4, check whether the measured sample surface is neat, there are no impurities mixed color, if the measured sample color is a mixed color, then it is difficult to accurately assess the measurement results.