JPH08313353A - Colorimetric value correction method - Google Patents

Abstract

(57) Abstract: Provided is a method for correcting a colorimetric value, which is capable of always performing a measurement operation with high accuracy and easily without causing a measurement error due to a temperature variation even under an arbitrary temperature condition. SOLUTION: A colorimeter (spectrophotometer, colorimeter or densitometer) is used to measure at any temperature of a colored sample, and the obtained colorimetric value is measured under at least two different temperature conditions. It is corrected by the amount of change obtained from the difference between.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for correcting colorimetric values of various colored objects, and more specifically, colorimetric measurement capable of always performing measurement operation with excellent accuracy by correcting errors in measured values due to temperature changes. Regarding the correction method of the value.

Recently, in managing the color of colored products,
For example, a method of using digitized colorimetric values such as L ^* , a ^* , b ^* and Munsell value is widely used. However, there is a drawback that the obtained colorimetric value fluctuates depending on the measurement temperature and gives an error. For this reason, when measuring the colors of multiple samples and comparing the colors, the conventional method is to use the colorimetric values measured under the same temperature conditions or to re-measure the standard samples each time and compare. Has been done.

[0003]

2. Description of the Related Art Usually, a change in colorimetric value due to temperature is about 0.1 to 0.1 as a color difference (ΔE ^* ) when the temperature changes by 1 ° C.
An error of 0.3 occurs. Therefore, when more accurate measurement is required, it is necessary to perform the measurement operation while controlling the temperature of the sample within about ± 1 ° C, but the sample temperature should be kept within ± 1 ° C for each measurement. Because adjustment involves expensive equipment and complicated operations, a method is usually adopted to measure the standard sample and color sample to be measured at the same time to eliminate the effects of errors due to temperature changes. There is.

However, the operation of repeatedly measuring the color of the standard sample is not only a complicated management process, but also care must be taken so that discoloration or contamination does not occur during the long-term storage of the standard sample. In addition, there is an inconvenient problem that a standard sample must be prepared each time measurement is performed, because a sample that changes color over time during storage cannot be used as a standard sample.

Further, for example, when colorimetrically measuring products continuously produced in a production process line, outdoor products, buildings, etc., it is difficult to perform measurement without temperature change. There are quite a few cases in which a colorimetric value including an error is used as it is.

[0006]

The present inventors have investigated the relationship between the temperature of a colored object and the colorimetric value in order to elucidate the temperature dependence of the colorimetric value in detail. Knowing that variations in colorimetric values based on
Further, it was confirmed that the colorimetric value under a given temperature condition can be corrected to a colorimetric value at a specific temperature by utilizing the variation phenomenon of the colorimetric value depending on the temperature.

The present invention was developed on the basis of the above-mentioned findings, and its object is to always perform measurement operation with high accuracy and simply without any measurement error due to temperature change under any temperature condition. It is to provide a method of correcting a colorimetric value that is effective as a management process capable of performing.

[0008]

A method for correcting a colorimetric value according to the present invention for achieving the above object is a colorimetric value obtained by measuring a colored sample at an arbitrary temperature using a colorimeter. Is characterized in that it is corrected by the amount of change obtained from the difference between the measured values under at least two different temperature conditions.

The colorimeter used in the present invention is selected from a spectrophotometer, a colorimeter and a densitometer. Further, the amount of change serving as the correction coefficient in the present invention is given by the difference between the values measured under at least two different temperature conditions for the reference colored sample. The reference colored sample does not have to be a specific colored object, and for example, a plastic material colored with various dyes and pigments or a metal material colored with a paint can be used. Specifically, a colorimetric value at a temperature between arbitrary two points of the colored sample, for example, 30 ° C. and 50 ° C. is calculated,
This is used as a correction coefficient as the amount of change per predetermined temperature.
At this time, the change amount is the difference between the change amounts per 1 ° C.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION A method for correcting a colorimetric value according to the present invention measures a colorimetric value of a colored sample to be measured by a colorimeter at an arbitrary temperature, and changes the obtained colorimetric value to its change. It is done by correcting with a quantity. Spectral reflectance, tristimulus values, and values of various display systems are used as the measurement values and the correction values.

For the measurement operation of the colorimetric value, a temperature sensor can be built in a device such as a spectrophotometer, a colorimeter, and a densitometer, and the sensor can be designed to detect the measured temperature. It is also possible to specify the temperature with the keyboard and execute. Further, if the colorimetric value of the sample to be measured measured at an arbitrary temperature is converted to a specific temperature and made into a database, it becomes more convenient for process control.

The colorimetric object according to the present invention can be applied not only to paints and inks containing dyes and pigments, products colored with these such as plastics, fibers and papers, but also to colored objects existing in nature. it can.

The present invention employs a method of correcting a colorimetric value measured at an arbitrary temperature to a colorimetric value of a specific temperature by utilizing the correlation existing between the colorimetric value and the temperature, and thus the industrial method This is established as a color measuring method suitable as a management method. That is, according to the present invention, the measured value difference (change amount) of the colored sample measured under different temperature conditions between at least two points is obtained as a correction coefficient per unit temperature, and the measured value measured at any temperature is measured. By converting the colorimetric value of the sample into a value at the target temperature using the correction coefficient, it is possible to effectively eliminate the influence of measurement error due to temperature change.

Therefore, accurate colorimetric values can always be measured by simple operations, and simulation can be performed at any temperature, which is extremely effective as a routine measurement management process of colorimetric values. .

[0015]

EXAMPLES The present invention will be described in detail below in comparison with comparative examples. However, the present invention is not limited to these examples.

Example 1 A color sample P29-110 of a standard sample book (wide version) for paint issued by Japan Paint Manufacturers Association (P version in 1988) was used as a reference colored sample, and a spectrophotometer [Dainichi Seika Kogyo Co., Ltd. Manufactured by K. Co., Ltd.) was used to measure the spectral reflectance at a sample temperature of 10 ° C. and 40 ° C. in the wavelength range from 380 nm to 700 nm in units of 10 nm. Temperature difference of 30 ℃
The amount of change (ΔR) per 1 ° C. was calculated for each wavelength from the difference value of the spectral reflectance of the above, and the results shown in Table 1 were obtained.

[0017]

[Table 1]

Next, 1 for each colored sample to be measured.
Spectral reflectance was measured with the same spectrophotometer under the conditions of each sample temperature of 0 ° C, 20 ° C, and 30 ° C, and the amount of change (ΔR) shown in Table 1 was used as a correction coefficient to predict the reflection at 20 ° C temperature. The Munsell value was calculated from the predicted reflectance value by obtaining the reflectance value. The results are shown in Table 2. In addition, obtained 2
10 ℃ and 30 based on Munsell value of 0 ℃
The color difference (ΔE) from the Munsell value at 0 ° C is also shown in Table 2.

[0019]

[Table 2]

From this result, it is recognized that the Munsell value due to the temperature change is suppressed to a very small variation range by the correction and can be obtained as a highly accurate measured value.

Examples 2 to 5 Four colors were selected from the standard sample book for paint (wide version) published by the Japan Paint Manufacturers Association (P edition in 1988) and used as reference colored samples, and the same measurement as in Example 1 was carried out. The Munsell value was calculated by correcting and converting the spectral reflectance of the colored sample. The results obtained are shown in Table 3. From the results in Table 3, it is found that the error in the color difference (ΔE) due to the temperature change is extremely small regardless of the difference in hue.

[0022]

[Table 3]

Comparative Examples 1 to 4 Four colors were selected from the standard sample book (wide version) for paint published by Japan Paint Manufacturers Association (P edition in 1988), and these were used as reference colored samples at 10 ° C, 20 ° C and 30 ° C. The spectral reflectance was measured at each sample temperature and the Munsell value was directly calculated from the measured value and the color difference (ΔE) is shown in Table 4. From the results in Table 4, the color difference (ΔE) compared to the corresponding examples (see Table 3)
It was confirmed that the values vary greatly.

[0024]

[Table 4]

Example 6 A pigment having the same hue as in Example 1 was mixed with a polyethylene resin to prepare a colored plastic molded plate, and the colorimetric value was measured in the same manner as in Example 1. The results obtained are shown in Table 5.

[0026]

[Table 5]

From the results shown in Table 5, even in the case of a molded plate obtained by coloring a plastic with a dye or pigment, as in the case of the coated plate of Example 1,
It has been proved that the accuracy is industrially satisfactory and that the present invention can be effectively applied regardless of the colored substance.

Examples 7 to 12 and Comparative Examples 5 to 10 A colored polyvinyl chloride plate (PVC: 100, stabilizer: 3, lubricant: 1) having a thickness of 1 mm was used as a sample, and 25 ° C, 40 ° C and 50 ° C were used.
The spectral reflectance was measured under the temperature condition of ° C. Obtained 25
The L ^* a ^* b ^* value was calculated from the actually measured reflectance at the temperature of ° C. Next, the change amount per 1 ° C is calculated from 40 ° C and 50 ° C,
Calculate the predicted reflectance at 25 ° C from each measured reflectance,
L ^* a ^* b ^* values were calculated. Table 6 shows the results, and the upper part of each example shows L obtained from the measured reflectance at 25 ° C.
^* a ^* b ^* value, the lower part is the corrected L ^* a ^* b ^* value and the color difference (ΔE ^* ) based on the upper part.

For comparison, 25 ° C., 40 ° C. and 50 ° C.
The L ^* a ^* b ^* value calculated from the spectral reflectance measured at ℃ and the color difference (ΔE) at 40 ℃ and 50 ℃ based on 25 ℃.
^* ) Is shown in Table 7. As is clear from comparing the results of Tables 6 and 7, it is recognized that the corrected color difference (ΔE ^* ) of the example is reduced to about 1/3 to 1/15 as compared with the uncorrected color difference of the comparative example. To be

[0030]

[Table 6]

[0031]

[Table 7]

[0032]

As described above, according to the present invention, it is possible to suppress variations in color measurement values, which are easily influenced by temperature, to a small range by a simple colorimetric value correction operation. Highly accurate comparison is possible. Moreover, even if the temperature control is not strictly controlled at the time of measurement, it becomes easy to convert the measured value to an absolute value at a specific temperature, and the standard storage management and re-measurement that have been performed conventionally are no longer necessary, so it is possible to use it in daily It is extremely useful as a process control method.

Claims (2)

[Claims] 1. A color sample is measured with a colorimeter at an arbitrary temperature, and the obtained colorimetric value is corrected by the amount of change obtained from the difference between the measured values under at least two different temperature conditions. A method for correcting colorimetric values, which is characterized in that 2. The method for correcting a colorimetric value according to claim 1, wherein the colorimeter is a spectrophotometer, a colorimeter or a densitometer.