JPH05231940A - Measuring method of surface color tone - Google Patents

Abstract

PURPOSE:To measure a surface color tone of a substance to be measured which has the color tone of an achromatic color system and is in movement, by measuring reflectances in three wavelengths (narrow wavelength bands) in a specific wavelength region of a visible light and by determining an average value of gradients of the reflectances among these three wavelength bands. CONSTITUTION:Three wavelengths (narrow wavelength bands) are selected from a reflected light in a visible light region of a substance to be measured and reflectances are determined. In other words, a central wavelength is selected from a wavelength range of 480 to 550nm and a reflectance in a wavelength band of + or -10nm or below in relation to the central wavelength is measured. Next, the central wavelength is selected from the wavelength range of 550 to 620nm and the reflectance in the wavelength band of + or -10nm or below in relation to this central wavelength is measured. Subsequently, the central wavelength is selected from the wavelength range of 620 to 700nm and the reflectance in the wavelength band of + or -10nm or below in relation to the central wavelength is measured. An average value of gradients (reflectance difference (%)/wavelength difference (nm) between central wavelengths) of the reflectances among these three wavelength bands is made a measured value of a surface color tone of the substance to be measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a colorimetric method suitable for measuring the surface color tone of an achromatic object such as tin-free steel (hereinafter referred to as TFS).

[0002]

2. Description of the Related Art TFS has anisotropy in that color tones differ in the width direction and the length direction. Therefore, the direct light from the light source cannot be used for the illumination when performing the colorimetry, and it is necessary to perform the scattered light illumination that irradiates the measurement point with light from all directions. As a colorimeter capable of scattered light illumination,
An integrating sphere type colorimeter called -d or d-O type is known. However, in the conventional integrating sphere colorimeter, it is necessary to bring the object to be measured in close contact with the detection unit so as not to be affected by external light, and the color of the object to be measured cannot be measured while moving. Compared to direct illumination from a light source, the amount of reflected light from the DUT is 1/2 in conventional scattered light illumination using an integrating sphere.
This is because it is extremely small, 0 to 1/100, and the difference in the amount of light with the outside light is small. Therefore, T which passes through this system
It cannot be applied to the FS strip colorimetric method.

In view of the above, the present applicant has previously proposed, as Japanese Patent Application No. 1-331038, a colorimetric method which enables the perfect evaluation of the surface color tone of a moving object to be measured. This method, the slope of the spectral reflectance curve of the object to be measured, specifically, the reflectance of the spectral reflectance curve peak of the wavelength from the wavelength to the longest wavelength of visible light in the appropriate wavelength range Based on the knowledge that the color tone of an object can be distinguished by the slope of the reflectance curve, the spectral reflectance curve of the DUT is determined, and the reflectance of this spectral reflectance curve is from the peak wavelength to the longest wavelength of visible light. 1 wavelength difference in the wavelength range
The average gradient of the reflectance curve with respect to the wavelength in the wavelength region of 00 nm or more is obtained, and this average gradient is used as the measured value of the color tone of the surface of the object to be measured. According to such a method, it is possible to measure the color tone of an achromatic object such as a moving TFS with a high degree of correlation with the visual evaluation. It is possible to bring about great effects on manufacturing, production control, and quality control.

[0004]

However, in this method, it is necessary to measure the spectral reflectance at every 10 to 20 nm in the wavelength range of visible light and calculate the gradient, and such a measurement can be performed online. Such a device must be very complicated and expensive. The present invention has been made to solve the above problems, and it is possible to easily perform online colorimetry even on the surface color tone of a moving object to be measured having an achromatic color tone such as TFS. It seeks to provide a way to do it.

[0005]

Means for Solving the Problems The inventors of the present invention have found the reflectances of three wavelengths (narrow wavelength bands) in a specific wavelength range of visible light, and have a gradient of the reflectances (reflectances between these wavelength ranges). It was found that the average value of (difference (%) / wavelength difference between central wavelengths (nm)) has a high correlation with the average gradient of the reflectance curve obtained by the colorimetric method according to Japanese Patent Application No. 1-3331038. The present invention has been completed.

That is, the present invention has a center wavelength in the wavelength range of 480 to 550 nm from the reflected light in the visible light range of an object to be measured and a reflectance in a wavelength range of ± 10 nm or less with respect to the center wavelength. , With a center wavelength in the wavelength range of 550 to 620 nm, a reflectance in a wavelength range of ± 10 nm or less with respect to the center wavelength, and a center wavelength in the wavelength range of 620 to 700 nm, and with respect to the center wavelength. The reflectance in the wavelength range of ± 10 nm or less is measured, and the average value of the gradient of the reflectance (reflectance difference (%) / wavelength difference (nm) between central wavelengths) between these three wavelength ranges is measured. A surface color tone colorimetric method characterized in that a measured value of a surface color tone of a measurement object is used.

Further, such a method of the present invention can be easily carried out by the following method. The object to be measured is irradiated with scattered light, and the reflected light of the object to be measured is captured by a color camera in which the light receiving characteristics of the red component, the green component, and the blue component are narrow band, and the respective reflectances are measured. The measured light is irradiated with scattered light, the reflected light of the measured light is dispersed by a spectroscope, and the light in the above three wavelength regions is extracted from the dispersed light with a slit plate having openings at multiple locations. , And measure the reflectance of each. The scattered light can be applied to the object to be measured by integrating sphere illumination in which a plurality of light sources are installed in different directions.

[0008]

In the method of the present invention, the average gradient of reflectance as the colorimetric value of an object is the average gradient of the reflectance curve obtained by the measuring method according to Japanese Patent Application No. 1-331038, that is, the wavelength in the visible light region. Regarding the spectral reflectance curve with a difference of 100 nm or more, it shows a very high correlation with the gradient obtained by simple regression of reflectance with respect to wavelengths of 10 to 20 nm.

Table 1 shows a comparison between the colorimetric values based on the average gradient of the reflectance curve obtained by the measuring method of Japanese Patent Application No. 1-3331038 and the colorimetric values according to the method of the present invention. In this measurement test, 10 sheets of TFS from A to J
About the sample C light according to JIS Z 8722-1981 condition b
The spectral reflectance was measured under the conditions of a visual field of 2 degrees and an angle of 0-45 degrees (incident angle-reflection angle). According to the method of Japanese Patent Application No. 1-331038, a reflectance-wavelength gradient (reflectance difference (%) / 10 nm interval / wavelength 480 nm to 700 nm at 10 nm intervals).
10 (nm)), and the average value of these is further 1000
A numerical value corrected to the gradient of the reflectance difference per nm was obtained and used as a colorimetric value.

On the other hand, according to the method of the present invention, in the visible light wavelength range of 480 to 700 nm, the wavelength range of 480 to 550 nm is 500 nm, the wavelength range of 550 to 620 nm is 600 nm, and the wavelength range of 620 to 700 nm is 7 nm.
Select each center wavelength of 00 nm (ie,
The central wavelength is selected at 100 nm intervals), and from the reflectance in the narrow wavelength range of ± 10 nm or less with respect to each central wavelength, the gradient of the reflectance between the wavelength ranges (reflectance difference (%) / 100 (n
m)) was obtained, and the average value of this gradient was further corrected to the gradient of the reflectance difference per 1000 nm to obtain a numerical value, which was taken as a colorimetric value.

Further, the wavelength range of visible light is 480 to 700.
nm from the wavelength range of 480 to 550 nm, 53
580n from the wavelength range of 0 nm and 550 to 620 nm
± 10 nm with respect to each center wavelength by selecting each center wavelength of 630 nm from the wavelength range of m, 620 to 700 nm (that is, selecting the center wavelength at intervals of 50 nm).
From the reflectance in the following narrow wavelength region, the gradient of the reflectance between the respective wavelength regions (reflectance difference (%) / 50 (nm)) was determined and used as the colorimetric value.

As is clear from Table 1, Japanese Patent Application No. 1-3
There is a high correlation between the colorimetric value obtained by the method of No. 31038 and the colorimetric value obtained by the method of the present invention, and the colorimetric value obtained based on the reflectance in three narrow wavelength ranges selected from a specific wavelength range. It can be seen that the surface color tone can be sufficiently measured even with the color value.

In the method of the present invention, the wavelength difference between the three central wavelengths selected as described above is preferably 50 nm or more. The wavelength difference between the central wavelengths is 50 nm
If the amount is less than the above, the correlation between the colorimetric value obtained by the method of Japanese Patent Application No. 1-3331038 and the colorimetric value obtained by the method of the present invention decreases, and accurate colorimetric values cannot be obtained. Further, in the method of the present invention, it is preferable to use a value obtained by further correcting the average gradient value based on the reflectance between the above three wavelength ranges to the gradient of the reflectance difference per 500 nm or more (for example, 1000 nm). This is because the average gradient value based on the reflectance between the above three wavelength regions is very small, and the handling becomes complicated when displaying the colorimetric value by the colorimetric apparatus according to the present invention.

The color camera divides the wavelength range of visible light into red component (R), green component (G), and blue component (B) for each pixel in its field of view, and corresponds to the amount of light in each wavelength region. The R, G, and B values are output as a voltage. Therefore, the R, G, and B light receiving characteristics of the color camera are narrowed around a specific wavelength, and the R, G, and B outputs of the color camera are the same in white with a uniform spectral reflectance in the visible light wavelength range. By doing so, the spectral reflectance in the vicinity of the specific wavelength described above can be measured. For example, 6 for R
It has a center wavelength in the wavelength range of 20 to 700 nm and has a characteristic of receiving light in a wavelength range of ± 10 nm or less with respect to the center wavelength, and G has a center wavelength in the wavelength range of 550 to 620 nm and In contrast, B has a characteristic of receiving light in a wavelength range of ± 10 nm or less, B has a center wavelength in a wavelength range of 480 to 550 nm, and has a characteristic of receiving light in a wavelength range of ± 10 nm or less with respect to the center wavelength, By measuring the spectral reflectance at each wavelength, the surface color tone of the measured object can be measured.

As a detector, a visible wavelength range (for example, 4
The reflected light from the surface of the object to be measured is dispersed by using a spectroscope (00-800 nm), a wavelength range of 620-700 nm, a wavelength range of 550-620 nm, and a wavelength range of 480-550.
The center wavelength is selected in each wavelength range of the wavelength range of nm, and for example, the center wavelength is set to 630 nm (R), 580
nm (G), 530 nm (B), a slit having a width that allows passage of a wavelength range of ± 10 nm or less is provided at these spectral positions, and the intensity of light that has passed through this slit can be measured. The spectral reflectances at 530, 580, and 630 nm can be measured by making the R, G, and B outputs of the detector the same in a white color with a uniform spectral reflectance in the wavelength range of The surface color of an object can be measured.

Scattered light is used for the colorimetric illumination. The scattered light is generated by, for example, mounting a plurality of fluorescent lamps in the box to form an illumination box and scattering the light using frosted glass. By disposing the illumination box in four directions with the color camera or the detector center, scattered light from all directions can be applied to the colorimetric position of the measured object. Further, when the scattered light is irradiated by the integrating sphere illumination, the light amount of the light source for irradiating the integrating sphere is increased, for example, by making light incident on the integrating sphere from multiple directions,
By illuminating the visual field of the color camera or the detector by creating scattered light in the integrating sphere, it is possible to irradiate the measurement position of the object to be measured with a sufficient amount of scattered light for measuring the intensity of reflected light.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram of a surface color tone measuring apparatus used for carrying out the present invention, FIG. 2 is a principle diagram of a color camera constituting the apparatus, and FIG. 3 is a characteristic diagram of the color camera.

In the method of the present invention, as shown in FIG. 1, the object to be measured 1 (for example, an object whose surface color tone is achromatic) is illuminated by the illumination boxes 3a, 3b, 3c and 3d in four directions centering on the color camera 2. The scattered light is emitted from the device, and the reflected light of the DUT 1 at the irradiation position is received by the color camera 2. Of the light received through the lens 6 as shown in FIG. 2, the color camera 2 first reflects only the light in the wavelength range of the blue (B) component by the dichroic mirror 7a and allows the light in other wavelength ranges to pass through. Then, the dichroic mirror 7b reflects light in the wavelength range of the green (G) component and allows light in other wavelength ranges to pass through. The light passing through the dichroic mirror 7b is passed through the filter 8 only in the wavelength region of the red (R) component. The light amounts of the light reflected by the dichroic mirrors 7a, 7b and the light passing through the filter 8 are measured by the light receiving elements 9a, 9b, 9c.

FIG. 3 shows an example of light receiving characteristics of the color camera 2. The dichroic mirror 7a in FIG.
As for the reflection characteristic of 7b and the characteristic of the filter 8, a central wavelength is selected in a wavelength range of 480 to 550 nm for a specific wavelength, for example, B, a central wavelength is selected in a wavelength range of 550 to 620 nm for G, and R is selected for R. Is 620-700
The characteristics of the color camera 2 as shown in FIG. 3 are obtained by selecting the center wavelength in the wavelength range of nm and narrowing the light receiving band at each of the center wavelengths to about ± 10 nm or less with respect to the center wavelength.

Therefore, according to the selection of the center wavelengths of R, G, and B described above regarding the light receiving characteristics of the color camera 2 shown in FIG. 1, for example, R is 700 nm, G is 600 nm, and B is 5 nm.
Select 00 nm. As a result, the color camera 2 that receives the reflected light from the DUT 1 has a reflected light wavelength range of 50.
It is possible to obtain B, G, and R outputs corresponding to reflectances near 0 nm, 600 nm, and 700 nm. The B, G and R outputs are sent to the arithmetic unit 5 through the camera controller 4,
In this arithmetic unit 5, wavelengths 500, 600, 7 in the visible light range
The average slope of the reflectance is obtained by simple regression based on the reflectance in the wavelength range having a center wavelength of 00 nm, and this is output as the colorimetric value of the surface color tone of the DUT 1. Further, in this method, the brightness of the surface of the DUT 1 can be evaluated by the average value of the reflectances in the wavelength regions having the respective central wavelengths of 500, 600 and 700 nm.

Next, an embodiment in which an integrating sphere is used for illumination and a spectroscope is used for the detector will be described. FIG. 4 and FIG. 5 are configuration diagrams of the surface color tone inspection device configured by an integrating sphere and a spectroscope, FIG. 6 is a principle diagram of the detector, and FIG. 7 is a drawing showing a light receiving characteristic of the detector using the spectroscope. is there.

In FIG. 4 and FIG. 5, the integrating sphere illumination device 10 irradiates the DUT 1 whose surface color tone is achromatic with scattered light. The integrating sphere illuminating device 10 has an integrating sphere body 11 and a plurality of light sources 12a, 12b, 12c for irradiating the DUT 1 with a large irradiation light amount, and from these light sources 12a, 12b, 12c. Of the irradiation light is taken into the inside of the integrating sphere body 11 from different positions, for example, at positions shifted by 120 ° and scattered inside the integrating sphere body 11, and the scattered light is taken out from the irradiation side opening O to be measured. 1 can be irradiated with scattered light. The inner surface of the integrating sphere body 11 is coated with a white material having a high reflectance, such as barium sulfate, to minimize the attenuation of scattered light.

The reflected light from the DUT 1 is the integrating sphere body 11
The light is taken in from the irradiation side opening O and is made incident on the detector 20 through the light receiving side opening I. The detector 20 has a light collecting unit 21,
The spectroscopic section 22 and the light receiving section 23 are provided, and the incident light is guided to the spectroscopic section 22 through the condensing section 21. The incident light is dispersed by the spectroscopic unit 22 in the visible wavelength region, for example, in the wavelength band of 400 to 800 nm, and the wavelength range of 480 to 550 nm and 5
The center wavelength is, for example, 53 in the respective wavelength ranges of 50 to 620 nm and 620 to 700 nm.
Light of 0, 580, and 630 nm is extracted and guided to the light receiving unit 23. The light receiving section 23 measures the intensity of the light of the central wavelength,
Convert to electrical signal.

According to FIG. 6, the light incident on the condenser 21 is condensed by the lens 24, is collimated again by the lens 26 through the slit 25, then enters the spectroscope 22, and the spectroscope 2 is used.
7, the light is dispersed in the wavelength band of, for example, 400 to 800 nm, and the split light is applied to the slit plate 28. The slit plate 28 has a specific wavelength position, for example, 530 nm,
Slits S at 580 nm and 630 nm, respectively
a, Sb, Sc are opened, and these slits S
The light receiving wavelength band can be determined to be, for example, about 20 nm by the aperture widths of a, Sb, and Sc. The slits Sa, S
The light passing through b and Sc receives the light receiving elements 29a, 29b, 29.
The light is received by c and converted into an electric signal corresponding to the intensity of each passing light. These electric signals are sent to the amplifier 30, and the electric signals which are easy to handle, for example, the reflectance is 0 to 0.
DC, 0 to 10V Ba, Ga,
Converted to Ra. If the DUT 1 is measured using a standard plate whose reflectance is known in advance, electric signals Ba, Ga, Ra corresponding to the reflectance of the DUT 1 are obtained.

FIG. 7 shows an example of the light receiving characteristic of the detector 20 using a spectroscope. The spectral range of the spectroscope 27 in FIG. 6 is, for example, 400 to 800 nm in the visible light range,
Specific wavelength, eg 480-550 nm for Ba
Select the center wavelength in the wavelength range of
The central wavelength is selected in the wavelength range of 620 nm to 620 nm, the central wavelength is selected in the wavelength range of 620 to 700 nm for Ra, and the light receiving band at each of these central wavelengths is narrowed to about ± 10 nm or less with respect to the central wavelength. By providing the slits Sa, Sb, and Sc having different aperture widths at the positions of the respective special wavelengths, the characteristics of the detector 20 using the spectroscope as shown in FIG. 7 can be obtained.

From the above, from the reflected light of the DUT 1 in FIGS. 4 and 5, for example, wavelength bands of 530 nm and 580
signal B corresponding to the reflectance in the vicinity of nm and 630 nm
It is possible to obtain a, Ga and Ra outputs. Electric signal B
The a, Ga, and Ra outputs are sent to the arithmetic unit 5, and in the arithmetic unit 5, wavelengths in the visible light range of 530 nm, 580 nm, 6
The average slope (reflectance difference% / 50 nm) of the spectral reflectance is obtained by single regression of reflectance at 30 nm and each wavelength,
The surface color tone of the DUT 1 is evaluated by a value obtained by further correcting the average value to the reflectance difference per 1000 nm. Also, 530
The brightness of the surface of the DUT 1 can also be evaluated by the average value of the reflectance at nm, 580 nm, and 630 nm. According to the surface color tone measuring method according to the present invention described above, for example, in a continuous manufacturing facility of TFS or the like, by setting the country value in the color measuring value and the brightness, an online tone adjusting guidance is provided. It is also possible to issue an abnormal alarm.

Next, an example of measurement test using the above colorimetric method will be described. In this measurement test, the amount of metallic chromium is usually 70 to 130 mg /
m ² and a hydrated chromium oxide amount of 10 to 20 mg / m ² (in terms of Cr amount), a TFS sample on which a chromate film was formed was used as a test material. The grades were classified into A, B, C, and D in the order of good color tone to poor color tone.

With respect to this TFS sample, in the visible light wavelength range of 480 to 700 nm of reflected light, from the wavelength range of 480 to 550 nm, 500 nm, 5
From the wavelength range of 50 to 620 nm, 600 nm, 620 to 620
From the wavelength range of 700 nm to each wavelength of 700 nm is 100
Each is selected as a central wavelength at an interval of nm, and based on the reflectance in the wavelength range of ± 10 nm or less with respect to this central wavelength,
Gradient of reflectance between each wavelength range (reflectance difference (%) / 100
(Nm)), and the average value was further corrected to the gradient of the reflectance difference per 1000 nm to obtain a colorimetric value.

In addition, the visible light wavelength range 480 of the reflected light is obtained by the colorimetric method of the present invention having the above-described configurations of FIGS. 4 and 5.
˜700 nm, the wavelength range from 480 to 550 nm is 530 nm, and the wavelength range from 550 to 620 nm is 5
630n from the wavelength range of 80nm, 620-700nm
Each wavelength of m is selected as a center wavelength at intervals of 50 nm, and the gradient of the reflectance between the wavelength ranges (reflectance difference (%)) based on the reflectance in the wavelength range of ± 10 nm or less with respect to the center wavelength. / 50 (nm)) was obtained, and the average value was further corrected to the gradient of reflectance difference per 1000 nm to obtain a colorimetric value.

FIG. 8 shows the relationship between the colorimetric value thus obtained and the visual evaluation. According to the figure, by providing a stepwise threshold value for the colorimetric value according to the present invention,
It can be seen that the grades of A, B, C and D classified by visual judgment can be completely separated, and that the surface color tone of TFS can be classified by the method according to the present invention.

Next, TF using the above-described colorimetric method
An online measurement test example in the S manufacturing facility will be described. In this measurement test, in the TFS manufacturing facility,
The amount of metallic chrome on the surface of a cold rolled steel sheet for tin is 70 to 1
30 mg / m ² , hydrated chromium oxide amount 8 to ²⁰ mg / m ²
The surface color tone is changed by forming a film in which the amount of adhesion is changed in the range of (Cr amount conversion) or changing the amount of oil coating in the range of 0 to 10 mg / m ² , and the final step of the TFS manufacturing facility. Immediately before the coil winding, the surface color tone of TFS was measured by the color measurement method of the present invention. Further, a sample is cut out from the measurement position, and this sample is used in Japanese Patent Application No.
It was compared with the measured value of the surface color tone by the colorimetric method shown in No. 331038 (hereinafter referred to as "comparative method").

9 to 12 show TF according to the method of the present invention.
The relationship between the measured value of S surface color tone and the measured value of TFS surface color tone by the comparison method is shown. Of these, FIG. 9 and FIG.
Is an online test with a color camera, Fig. 11 and Fig. 12
Is based on an online test using a spectroscope.
According to these, a high correlation is obtained between the colorimetric value of the TFS surface color tone by the method of the present invention and the colorimetric value of the TFS surface color tone by the comparison method, and the method of the present invention is used for the online colorimetric measurement of the TFS surface color tone. It can be seen that a highly reliable measurement value can be obtained even by using the colorimetric value according to, and the surface color tone can be adjusted in manufacturing.

[0033]

As described above, according to the present invention, even an object such as a TFS strip whose surface color tone is an achromatic system and which is moving can be measured with high accuracy. In such a colorimetric method of the present invention, the color tone of the measured object can be measured only by the reflectances of the reflected light of the measured object at the three wavelengths, and the color tone can be measured while irradiating the measured object with scattered light. Since it can be easily implemented by using a camera or a detector having a spectroscope, there is an effect that color tone management and color tone adjustment can be performed online with simple and inexpensive equipment. For this reason, the surface quality information can be grasped during the manufacturing in the TFS manufacturing line or the like, which is very effective in stabilizing the quality and improving the yield.

[0034]

[Table 1]

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an example of a surface color tone measuring device used for carrying out the present invention.

FIG. 2 is a principle diagram of the color camera used in FIG.

FIG. 3 is a characteristic diagram of the color camera used in FIG.

FIG. 4 is a configuration diagram showing another example of the surface color tone measuring device used for carrying out the present invention.

5 is a sectional view taken along line VV of FIG.

6 is a principle diagram of a detector using the spectroscope shown in FIG.

FIG. 7 is a drawing showing a light receiving characteristic of a detector using the spectroscope shown in FIG.

FIG. 8 is a diagram showing a relationship between a colorimetric value obtained in an example of the present invention and visual evaluation.

FIG. 9 is a drawing showing the relationship between the colorimetric value of TFS surface color tone by the method of the present invention and the colorimetric value of TFS surface color tone by the comparison method.

FIG. 10 is a drawing showing the relationship between the colorimetric value of TFS surface color tone by the method of the present invention and the colorimetric value of TFS surface color tone by the comparison method.

FIG. 11 is a drawing showing the relationship between the colorimetric value of TFS surface color tone by the method of the present invention and the colorimetric value of TFS surface color tone by the comparison method.

FIG. 12 is a drawing showing the relationship between the colorimetric value of TFS surface color tone by the method of the present invention and the colorimetric value of TFS surface color tone by the comparison method.

[Explanation of symbols]

1 ... Object to be measured, 2 ... Color camera, 3a, 3b, 3c,
3d ... Illumination box, 4 ... Camera controller, 5 ... Computing device, 6 ... Lens, 7a, 7b ... Dichroic mirror,
8 ... Filter, 9a, 9b, 9c ... Light receiving element, 10 ...
Integrating sphere lighting device, 11 ... Integrating sphere body, 12a, 12b,
12c ... Light source, 20 ... Detector, 21 ... Condensing part, 22 ... Spectral part, 23 ... Light receiving part, 24 ... Lens, 25 ... Slit plate, 26 ... Lens, 27 ... Spectrometer, 28 ... Slit plate,
29a, 29b, 29c ... Light receiving element, O ... Irradiation side opening, I ... Light receiving side opening, Sa, Sb, Sc ... Slit

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Mamoru Inaba 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Shinsuke Watanabe 1-2-1 Marunouchi, Chiyoda-ku, Tokyo Main Steel Pipe Co., Ltd.

Claims (4)

[Claims] 1. From the reflected light in the visible light range of the measured object, 48
Having a center wavelength in the wavelength range of 0 to 550 nm and a reflectance in a wavelength range of ± 10 nm or less with respect to the center wavelength;
It has a center wavelength in the wavelength range of 550 to 620 nm, a reflectance in a wavelength range of ± 10 nm or less with respect to the center wavelength, and a center wavelength in the wavelength range of 620 to 700 nm,
The reflectance in the wavelength range of ± 10 nm or less with respect to the central wavelength is measured, and the gradient of the reflectance (reflectance difference (%) / wavelength difference between the central wavelengths (n
A method for measuring the surface color tone, wherein the average value of m)) is used as the measured value of the surface color tone of the object to be measured. 2. A reflected light of an object to be measured is captured by a color camera which irradiates the object to be measured with scattered light and narrows the light receiving characteristics of the red component, the green component and the blue component, and has a wavelength range of 480 to 550 nm. Has a central wavelength at ± 10n with respect to the central wavelength
reflectance in the wavelength range of m or less and 550 to 620 nm
Has a center wavelength in the wavelength range of
Reflectance in the wavelength range of 0 nm or less, 620 to 700
The surface color tone colorimetry method according to claim 1, wherein the surface color tone has a center wavelength in a wavelength range of nm and the reflectance in a wavelength range of ± 10 nm or less with respect to the center wavelength is measured. 3. An object to be measured is irradiated with scattered light, the reflected light of the object to be measured is dispersed by a spectroscope, and a slit plate having openings at a plurality of locations provides 480 to 550 of the separated light.
having a center wavelength in the wavelength range of nm, light in the wavelength range of ± 10 nm or less with respect to the center wavelength, and having a center wavelength in the wavelength range of 550 to 620 nm and having a center wavelength of ± 10 nm.
measuring the reflectance of each of the light having a wavelength range of nm or less and the light having a center wavelength in the wavelength range of 620 to 700 nm and having a wavelength range of ± 10 nm or less with respect to the center wavelength. The surface color tone colorimetry method according to claim 1. 4. The surface color tone colorimetry method according to claim 2, wherein the object to be measured is irradiated with scattered light by integrating sphere illumination in which a plurality of light sources are installed in different directions.