JPS6014132A - Colorimetric device of surface of moving object - Google Patents

Abstract

PURPOSE:To perform the remote colorimetry of the surface of a moving object continuously with a high precision and a high responsiveness, by irradiating a white light, which has >=200-fold illuminance of an external light, to the surface of the moving object at 45 deg. to the surface alignment. CONSTITUTION:The white light having >=200-fold illuminance of an external light is irradiated to the surface of a moving object 10 at an angle theta=45 deg. to a furface alignment C from a white light source 14 through a lens 16. A surface alignment component out of the irregularly reflected light from the surface of the object 10 is focused by a condenser lens 20. A slit 22 prescribes a measuring place on the focusing surface of the lens 20. A collimator lens 24 collimates the light transmitted through the slit 22. A diffraction grating 26 subjects the light to spectral diffraction, and spectral components are reflected on a concave mirror 28, and intensities of them having respective wavelengths are detected simultaneously by a photodiode array 30. The electric signal for each wavelength is subjected to an operation processing in an operation processing device 31, and an average chromaticity or a color difference from a standard sample on a certain area in the running direction of the surface of the moving object is attained continuously.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color measuring device for the surface of a moving object, and is particularly suitable for use in controlling the color tone of a surface-treated steel sheet such as a colored steel sheet, or for measuring the temperature of a cold-rolled steel sheet. ·Color,
The present invention relates to an improvement in a color measuring device for the surface of a moving object, which continuously measures the color tone of the surface of a moving object, and is suitable for use in determining the quality of pickling of a pickling plate.

It is important to control the color tone of surface-treated steel sheets and assemblies, such as colored steel sheets, but as line speeds increase and the color unevenness and color differences that need to be detected become more subtle, it is difficult to detect them with the naked eye of workers. It's reaching its limit. This is because it requires a great deal of effort and skill, and there are problems with detection accuracy due to individual differences and various disturbances. On the other hand, off-line inspections are also carried out by sampling during manufacturing, but this has the disadvantage that the response is delayed and it is difficult to provide feedback to operations.

In view of these problems, various online color measurement devices have been devised and commercialized. For example, JP11α55
No. 95839 uses a filter to independently measure the tristimulus values X, Y, and Z as recommended by the International Commission on Illumination. Although the processing time can be shortened by C, it is impossible to obtain a spectral distribution! The problem is that once in a while is sad.

In addition, Japanese Patent Publication No. 1196/1986 measures color tone by varying the wavelength using a spectral light source and measuring the spectral reflectance using a cavity and a rotating sector. Although this method improves accuracy, it requires a large number of moving parts. , and if the measurement object moves at high speed in order to change the light source wavelength, +Iii!
There is a problem that continuous measurement cannot be performed at high density. Furthermore, Japanese Patent Application Laid-Open No. 10786/1986 irradiates white light in a linear manner, spectrally spectrally reflects the diffusely reflected light, and uses a two-dimensional imager (
It is necessary to calculate the chromaticity at each linear position by measuring the reflection intensity, but this method also requires the calculation of chromaticity after capturing the electrical signal obtained by receiving light. It takes a long time to scan, and even if the imaging device scans only in the wavelength direction and reads out data for each wavelength at the same point, the object to be measured is moving at high speed. if,
There are problems in that the measurement points are intermittent in the traveling direction, and the light receiving device is also expensive.

Furthermore, Japanese Patent Application Laid-open No. 52-102780 discloses a method that simultaneously disperses light from a sample object and receives the light simultaneously with multiple detectors to perform colorimetric calculations. This method uses a focusing lens in front of the slit. Since it is not equipped with a light source, it can be applied to transparent objects where the light from the light source can be used effectively.However, since the current obtained by the detector is extremely small, when performing colorimetry on reflective objects, it is necessary to In order to increase the intensity, the optical system must be brought extremely close to the sample object, and as a result, uneven illumination of the illumination light and minute positional fluctuations between the measuring instrument and the object to be measured directly affect the measurement data. There is a problem, particularly when the object to be measured is located far away and remote side coloring is performed. Furthermore, 3 using commercially available filters
The color separation type telephoto color meter has problems of poor accuracy and slow response speed. Furthermore, in those that apply the integrating sphere method used to measure the turbidity of liquids,
The use of an integrating sphere increases the size of the device, and it is also difficult to change the area of the surface to be measured or to place a standard plate for calibration, and the dirt inside the sphere makes measurement difficult. There was a problem in that the reliability of the ``i'' was lost or lost, so maintenance work was often required.

This technology has been developed to solve these conventional problems. The purpose is to provide a color measuring device.

The present invention provides a color measurement device for the surface of a moving object that emits white light having an illuminance 200 times or more of external light onto the surface of the moving object from a direction at an angle of 45°±10° with the surface normal. A plurality of light source units capable of image irradiation, a condensing lens system for forming an image of the surface normal component of the diffusely reflected light from the surface of the moving object, and an odor (a measurement site It is equipped with a built-in slit for spectroscopic measurement, a spectroscope for separating the light that has passed through the Surins 1 to 1, and a photodetection element that can simultaneously detect the intensity of the light of each wavelength separated by the spectroscope. , a colorimetric unit formed integrally with the plurality of light source units, and an Ic calculation process for obtaining color information on the surface of the moving object by calculating and processing electrical signals obtained by a photodetection element of the colorimetric unit. The above object has been achieved by comprising the following apparatus.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

As shown in FIG. 1, this colorimeter A measures the surface of a moving object 10 at an angle of θ-45° with the plane direction C from the J direction.
It has two built-in white light sources 14 that emit white light with an illuminance 200 times that of external light, and each white light source #A1
4m, a light source lens system 16 is installed for irradiating the light emitting body image of the light source onto the surface of the moving object 10.
2, and diffusely reflected light from the surface of the moving object 10,
A condensing lens system 20 for imaging plane line components, a slit 1-22 for defining a measurement area on the imaging plane of the condensing lens system 20, and converting the light passing through the slit 22 into parallel rays. A collimator lens 24 for converting the light into parallel light by the remeter lens 24, a reciprocal diffraction grating 26 serving as a spectrometer for separating the light into parallel light beams in the iIJ visual wavelength range, A concave mirror 28 for reflecting the light of each wavelength reflected by the concave mirror 28, and a photodetecting element such as Noah II to a diode array 30 capable of simultaneously detecting the intensity of the light of each wavelength reflected by the concave mirror 28 are built-in. Color measurement unit '1 formed integrally with a plurality of light source units 12
8, and the 7-otodiode Inoy 30 of the 3111 e section 18 calculates the average chromaticity of a certain area in the traveling direction of the surface of a moving object or a standard sample by processing the electrical signals for each wavelength (η). The color difference between
ζ consists of an arithmetic processing unit 31 consisting of a micro-nobuter and the like for ascending.

The irradiation angle θ of the light from the white light source 14 of the handle 12 is set to 4.
The reason for setting the angle to 5° is as follows. Figure 2 shows that for various color samples, standard color samples and limit samples of different colors are prepared.
The determined color difference value is set as ΔE0, and the angle θ with the surface direction line C in the optical system shown in Fig. 1 is set to a mutually equal angle on the surface to be measured using the water colorimeter @A. If △E is the color difference measurement value when the color difference is changed while maintaining the condition that
The results of investigating the angle dependence of are shown. From the results in Figure 2, it can be seen that when the irradiation angle θ is 45°, the absolute value of the difference between the constant values on both sides is the smallest, and within the range of 45° ± 10°, it is within 596 and can be used sufficiently. Recognize. The irradiation angle θ was set to 45° in consideration of this point.

Next, the reason why the light source section 12 is made up of two is as follows. FIG. 3 shows changes over time in measured values when there is one light source section 12 and when there are two light source sections 12. The amount of variation is expressed as the relative output intensity of the measured colorimetry 1 and the standard color value.

As is clear from the figure, when two lights 181S12 are provided, there is almost no variation, but when one light is used, the variation is larger. This can be understood to be because the temporal changes in the light source intensity are averaged out, and the illuminance unevenness caused by the filament image caused by imaging is also reduced by the combination of 'e' number of light sources. The reason why the white light source 14 is composed of two is to take this point into account and to provide temporally uniform light.

Furthermore, the reason why the irradiation intensity was 200 times that of external light was as follows.
Due to the reason. This apparatus A does not have an external shielding part having a complex structure such as an integrating sphere system. Therefore, it has the advantage that it can be measured at any location with relative ease, but it is affected by external light.

When the irradiation angle θ was 45° and the surface to be measured was irradiated with external light, the dependence of the color difference measurement error on the irradiation illuminance was investigated, and the result was as shown in FIG.

In the figure, LSIXj at d3 represents the illuminance of the light source, and LO[L×1 represents the external light illuminance. It is clear from the figure that J, sea urchin light source illuminance LS1. LX] is the external light illuminance and OIX] is 200
If it is more than twice the standard value, it can be confirmed that the absolute value of the difference between the value measured by Water Apparatus A and the standard JP value is within 5% of the standard value. Therefore, considering this point, 200% of external light
The irradiation intensity was doubled. Since there are a plurality of light source units 12, this realization is relatively easy.

Furthermore, the reason why each light source unit 12 is provided with a light source lens system 16 to cover the surface of the moving object 10 with a light emitting body image of the light source is to provide stronger irradiation intensity with the same light source and the same supply voltage. It's the first thing I get.

By adopting the above configuration next to the light source section 12, the influence of ambient light can be relatively reduced, the signal S/N ratio is improved, and the supply voltage can be lowered, resulting in longer lamp life and savings. Electricity can also be measured. Note that the white light source 1
As for 4, specifically, it is preferable to use a stable white light source such as a halogen lamp, and to perform effective illumination using heat-resistant glass such as Pyrex or quartz. In addition, in J3 of this embodiment, a photodetector 17 (Fig. 5) is attached to the light source section 12 in order to correct fluctuations in light source intensity, and the colorimeter section 1
The signal intensity obtained by 8 is corrected to eliminate measurement errors caused by fluctuations in light source intensity, and is also used to monitor the life of the light source.

In the color measurement section 18, a spectrometer is used as a -C diffraction grating 26.
Using the slit 22 and photodiode array 30, match i! The difference is that the dispersion angle of the diffraction grating 26C has a linear relationship with the wavelength, so the difference between Surin 1-22 and No;t l-
By using the diode array 30 in combination, the reflected light from the measurement surface defined by the slit 22 is separated and then applied to each channel at equal wavelength intervals on the photodiode array 30. This is because it is convenient for circuit design and manufacturing of optical systems and signal processing sections. That is, for example, if a 35-element photo die array 30 is used, by selecting conditions such as the geometric door opening of the optical system, the width of the
Using one element, it is possible to detect the spectral intensity in the visible wavelength range of 400 to 700 nm at intervals of 1Qnll1 wavelengths, and it is possible to obtain sufficient accuracy for colorimetry.

The reason why the embellishing section 18 and the light source section 12 are integrally formed is as follows. That is, remote color measurement device A having the above structure
For example, when used in a line that continuously produces copper strips, paper, etc., it is often necessary to measure the width of the object, not just the longitudinal force. At that time, the light source section 12
, and the colorimeter 18 at the same time. However, as mentioned above, in order to suppress uneven illuminance, multiple light sources 12 are irradiated to form an image, and in order to overlap each other's images, each light source must be scanned simultaneously. It is necessary that the relative position of the section 12 with respect to the colorimetric section 18 is always constant. Even if there are a plurality of light source sections 12, if they are all integrated with the color measurement section 18, such positional deviation will not occur. Furthermore, since the entire device is compact, it also has the advantage of making scanning easier. This is the reason why the color measurement section 18 and the light source section 12 are integrated.

As shown in FIG.
The electrical signals obtained by the photodiode array 30 of 8 are processed according to the signal processing time of the subsequent stage. l:
Analog processing circuit 32 that performs analog integration processing using integration time
and an analog-to-digital converter 34 that converts the analog signal output from the analog processing circuit 32 into a digital signal.
and a digital processing circuit 36 for obtaining color information on the surface of the moving object by processing the digital signal output from the analog-to-digital converter 34. That is, this Entaku TgA device 31 is shown in detail in FIG. 9.
111, preamplifiers 3281 to 32an for amplifying the output of each sensor 30+ to 30n of the photodiode array 30, and preamplifiers 32a1 to 32a.
Integrator 321 for integrating the output of n] 1 to 321
) n, a 1-multiplexer 34a for sequentially taking in the outputs of the integrators 321)+ to 32bn, and an analog-to-digital converter 34b for converting the analog signal output from the multiplexer 34a into a digital signal. , a preamplifier 32c for amplifying the output of the light source light amount detector 17 for detecting the intensity of the white light source 14, and the preamplifier 32
an analog-to-digital converter 34c for converting the C output output signal into a digital signal;
A central processing unit (hereinafter referred to as CPtJ) 36a for performing various calculation processes according to the outputs of the digital converters 341) and 340, and a central processing unit (hereinafter referred to as CPtJ) 36a for recording programs, various constants, and calculation data in the CPU 36a. a memory 36b, a program counter 360, and the CP
It is comprised of a digital-to-analog converter 36d for converting the digital signal output from U36a into an analog signal and outputting it to an output device 38 consisting of an output display or the like.

The analog processing circuit 32 amplifies, for example, 31 electrical signals obtained by the photodiode array 30 of the color embellishing section 18, and performs an integral calculation to obtain parameter values necessary for chromaticity calculation as electrical signals. here,
Analog integration is performed to shorten calculation time and to make the measurement surface continuous. That is, by setting the integration time according to the time required for computation, input/output, etc. in the digital processing circuit 36, the digital processing circuit 36 performs digital processing during integration, shortens the time required for digital processing, and Since it is possible to detect the intensity of reflected light from the entire surface of the measurement target that moves over time, the continuity of the measurement surface can be almost maintained. Often, an average chromaticity over a certain area is obtained, which is determined by the optical system such as a slit system, the moving speed of the measurement object, the integration time, etc.
Even if an inexpensive micron viewer is used, the processing time can be reduced to less than 20m5g, so the measurement surface will not be that large. Furthermore, since the signal strength can be increased, it has the advantage of being resistant to noise. On the other hand, as suggested in, for example, Japanese Patent Application Laid-Open No. 52-102780,
Directly transmit signals from diode array 30 etc.
If all arithmetic processing such as C, phase separator pupil, etc. required for chromaticity calculation is carried out in a digital camera, the calculation time will be long, and if the target object is moving at high speed, continuity cannot be maintained. However, in order to overcome this drawback, an expensive computer on the scale of a mini-computer with high calculation speed is required.

Furthermore, it is desirable to suppress the variation in amplification characteristics of the preamplifiers 3281 to 32an to within 0.1%.
Nijii. Since this device @A does not use an integrating sphere, it can be miniaturized, and the standard plate can be easily inserted in 1 t, making it easy to calibrate measured values. Furthermore, the measurement area can be easily changed by simple slit operation, and the maintainability of the device is also good.

Note that the optical system of this apparatus A satisfies the standard colorimetric conditions specified by the Japanese Industrial Standards (JIS) as is.

Next, the results of measuring the color tone of a colored steel sheet on an actual production line using the above-mentioned apparatus will be explained. As shown in FIG. 6, the device A is installed at a position where the moving object 10 travels vertically from above to below in front of the winding machine, after the color burn-in has been processed by the burn-in line B. . The distance between the moving object 10 and the collective lens system 20 is 500 inches, and
The irradiation angle θ was set to 451 in each case, and a halogen lamp with the same output (650 W) was used as the white light source 14.

After l+11 of this apparatus, rubber-lined holding rolls R1 and R2 were installed to keep the distance between the moving object 10 and the apparatus A constant.

During online measurement, we checked the relationship between the measured value (ΔE1) when external light was continuously connected and the measured value (ΔE) when natural light from ceiling lighting and windows was incident, as shown in Figure 7. We obtained the following results. From this, it became clear that there was almost no difference between the constant values on both sides.

Immediately, 650W has illumination intensity more than 200 times that of external light.
At Hoga@A, which used two halogen lamps, it was confirmed that the bright light in the factory did not affect the measured values.

After confirming this, under the environment where the factory lighting light is irradiated, the Δ-line measurement is performed and the value (ΔE) is 1 [value (ΔE)].
FIG. 8 shows the relationship between As is clear from the figure, the constant values on both sides coincide within a range of ±5%.

In addition, although the present invention is applied to the above-mentioned device for measuring the surface color tone of colored steel sheets, the scope of application of the present invention is not limited thereto. Monitoring of appropriate pickling conditions, measuring the surface color of plated steel sheets, stainless steel sheets, electromagnetic steel sheets, etc. in the rolling process, or measuring the whiteness of paper, color shift in printing, or product color in fields such as paper manufacturing and textiles. It is clear that this method can be similarly applied to color tone monitoring and the like.

According to the present invention described above, it is possible to perform remote color measurement of the surface of a moving object in a rational, highly accurate, highly responsive, and continuous manner, which is effective for product quality control and yield improvement. be. Moreover, it can be expected to be applied to color tone control and has excellent effects such as φ.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the overall configuration of an embodiment of the color measurement device for the surface of a moving object according to the present invention. FIG. 2 is a diagram showing the influence on measurement errors when the incident angle of the light source varies. , Figure 3 is a diagram showing the influence on the light source intensity fluctuation when there is one light source and when there are two light sources, and Figure 4 is a graph showing the influence on the measurement error of the ratio of external light intensity and irradiation intensity. FIG. 5 is a block diagram showing the configuration of the arithmetic processing device; FIG. 6 is an explanatory layout diagram showing an example in which the above embodiment device is applied to a color steel plate manufacturing line; FIG. A diagram showing a comparison of the measured values with and without external light during online measurement on the same line, and Figure 8 is a diagram showing a comparison between the online measured value on the 11]j line and the online measured value using the standard device. There is C. DESCRIPTION OF SYMBOLS 10... Moving object, 12... Light source part, 14... White light source, 16... Light source lens system, 18... Colorimeter,
20... Condensing lens system, 22... Slit, 26
...Diffraction grating (spectroscope) 30..., t1~tie A~door array (photodetection element), 31...pupil processing device, 32...analog processing circuit, 34...ana 1-1
Goo digital converter, 3G...digital processing circuit, 3
8... Output device, θ... Irradiation angle melon. Agent Takaya Lo (1 idiot) Fig. 1 Fig. 2) t, J, person M way summer action (deg) Fig. 3 □ r41 house a1 Fig. 4 0 0.5 l 1.5 (Lo/ Ls) x 200 evenings)
Figure 5, Figure 6, Figure 7 (Evening) Wakashita Koji IJ, Figure 8, 5-13-12 Daisawa, Setagaya-ku, Tokyo.

Claims (1)

[Claims] (1) Multiple light sources capable of irradiating the surface of a moving object from the J direction at an angle of 45°±10° with the surface normal, in an image form with white light with an illuminance more than 200 times that of external light. and a condensing lens system for forming an image of the surface normal component of the diffusely reflected light from the surface of the moving object, a slit for defining a measurement site on the imaging plane of the condensing lens system, and a slit for defining a measurement site on the imaging plane of the condensing lens system, and a colorimeter unit formed integrally with the plurality of light source units, which includes a spectrometer for separating the light and a photodetection element capable of simultaneously detecting the intensity of the light of each wavelength separated by the spectrometer; and an arithmetic processing device for obtaining color information on the surface of the moving object by performing interference processing on the electric signal obtained by the photodetecting element of the colorimeter. Colorimetric device.