JPS5957123A - Apparatus for measuring surface color of moving object - Google Patents

Abstract

PURPOSE:To enable remote color measurement good in responsiveness with high accuracy, by a method wherein scattered reflected lights from the surface of the object is received by a converging lens system while the intensities of lights with each wavelengths subjected to spectral diffraction by a spectroscope are simultaneously detected by detecting elements to be converted to electric signals and, after integration, operation treatment is performed. CONSTITUTION:The light from a white light source 4 is irregularily reflected on the surface of moving matter 10 and lights passing the slit 22 of an optical lens system are converted to parallel lights by a colimator lens 24 while lights subjected to spectral diffraction by a diffraction grating 26 are reflected by a concave mirror 28 to be subjected digital conversion by a A/D converter 34 through a circuit 32 for subjecting the electric signal output of a detector 18 in which a photodiode array 30 capable of simultaneously detecting lights with each wave forms is mounted to analogue treatment for a definite integration time. The outputs of the converter 34 are repeatedly subjected to operation treatment by a digital treating circuit 36 comprising a microcomputer to continuously obtain the average chromaticity of a definite area in the running direction of the moving matter or the color difference with a reference sample and the treating result is outputted from an output apparatus 38. As a result, remote color measurement can be performed with high accuracy and it is effective in quality control and yield enhancement.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color measurement device for the surface of a moving object, and in particular, it is suitable for controlling the color tone of the surface of a surface-treated steel sheet such as a colored steel sheet. This invention relates to an improvement in a color measuring device for the surface of a moving object that continuously measures the color tone of the surface.

It is important to control the color tone of surface-treated steel sheets such as colored steel sheets, paper, etc., but increasing the line speed,
As the color unevenness and color differences that need to be detected become more subtle.

Detection by the naked eye of workers is reaching its limits.

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 conducted by sampling during manufacturing, but this has the disadvantage that it is difficult to provide feedback to operations due to the delayed response.

In view of these problems, various online color measurement devices have been devised. It has been made into a 1IiJ product. For example, Japanese Patent Application Laid-Open No. 55-95839 uses a filter.

This method is recommended by the International Commission on Illumination and measures each of the tristimulus values xyzi independently, and although the processing time can be shortened, the problem is that accuracy suffers because spectral distribution cannot be obtained. My father, Special Publication No. 1196/1986, measures color tone by varying the wavelength using a 1-minute light source and determining the spectral reflectance using a cavity and rotating sector, which improves accuracy but requires a large number of moving parts. Yes, and when the object to be measured moves at high speed in order to change the light source wavelength.

Strictly speaking, there is a problem in that continuous measurement is no longer possible.

Furthermore, JP-A-54-10786 discloses a two-dimensional imaging device M? by irradiating white light in a linear manner and separating the diffusely reflected light. f-
The chromaticity is determined at each position along a line by measuring the reflection intensity using a digital camera, but even with this method, it takes a long time to calculate one chromaticity after capturing the electrical signal obtained by receiving light. (Also, since it is irradiated in a linear manner, the scanning of the imaging device.

Even if the measurement is carried out only in the wavelength direction and only the data of each wavelength at the same point is read out, if the object to be measured moves at high speed, the measurement points will be intermittent in the traveling direction, and the light receiving device is also expensive. There is a problem. Also, JP-A-52-
No. 102780 simultaneously disperses light from a sample object and receives the light simultaneously with multiple detectors to perform colorimetric calculations. Although it can be applied to transparent objects where the light from the light source can be effectively used, since the current obtained by the detector is extremely small, when performing colorimetry on reflective objects, the irradiation intensity will be increased. 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. This is particularly problematic when the object to be measured is located far away and remote color measurement is performed.

Furthermore, commercially available three-color separation type telephoto colorimeter using filter paste has problems of poor accuracy and slow response measurement.

The present invention has been made to eliminate the above-mentioned conventional drawbacks. It is an object of the present invention to provide a color measurement device for a surface of a moving object that can perform remote color measurement of the surface of a moving object with high precision, good responsiveness, and continuously.

The present invention provides a color measurement device for the surface of a moving object, which includes a light source section that irradiates the surface of the moving object with white light, and a ninth condenser lens system that forms an image of a part of the diffusely reflected light from the surface of the moving object. , a slit or pinhole for defining a measurement site on the imaging plane of the condensing lens system, a spectrometer for separating the light that has passed through the slit or pinhole, and each spectrometer separated by the spectrometer. a photodetection element capable of simultaneously detecting the intensity of light of different wavelengths; an analog processing circuit that performs analog integration processing on the electric signal obtained by the photodetection element in an integration time corresponding to a subsequent signal processing time; an analog-to-digital converter that converts an analog signal output from an analog processing circuit into a digital signal; and a digital processing circuit for obtaining color information on the surface of the moving object by processing the digital signal output from the analog-to-digital converter. The above object has been achieved by comprising the following.

Further, the light source section includes a plurality of light sources arranged at the same angle with respect to the surface of the moving object.

By providing a light source lens system for each light source to form and irradiate the light emitter image of the light source, the irradiation intensity on the surface of the moving object is stabilized and increased by one.

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

In this embodiment, as shown in FIGS. 1 and 2, a moving object 1
It consists of two white light sources 14 arranged at the same angle with respect to the surface of a moving object in order to irradiate white light onto the surface of A light source unit 12 is provided with a light source lens system 16 for irradiating an image onto the surface of the moving object IO, and -jolt' (i: a condensing lens system 20 for forming an image) of the diffusely reflected light from the surface of the moving object IO.゜Slit 22 for defining the measurement site on the imaging plane of the condenser lens system 20. The slit 2
A collimator lens 24 for collimating the light that has passed through the collimator lens 24, a diffraction grating 26 for simultaneously dispersing the light parallelized by the collimator lens 24 in the visible wavelength range, and a diffraction grating 26 for collimating the light that has passed through the collimator lens 24; A detector 18 (FIG. 2) includes a concave mirror 28 that reflects light of different wavelengths, and a photodiode array 30 that can simultaneously detect the intensity of light of each wavelength reflected by the concave mirror 28; The photodiode array 30 of the detector 18
an analog processing circuit 32 that performs analog integration processing on the electrical signals for each wavelength obtained by using a constant integration time corresponding to the signal processing time of the subsequent stage, and converts the analog signal output from the analog processing circuit 32 into a digital signal. By repeatedly processing the analog-to-digital converter 34 and the digital signal output from the analog-to-digital converter 34.

A digital processing circuit 3G consisting of a microcomputer or the like and outputting the processing results of the digital processing circuit 36 to continuously obtain the average chromaticity of a certain area of the surface of the moving object in the traveling direction or the color difference with a standard sample. and an output device 38 for printing.

The analog processing circuit 32, the analog-to-digital converter 34 and the digital processing circuit 36 are connected to each sensor 30-1 of the photodiode array 30, as shown in detail in FIG.
Preamplifier 32a for amplifying the output of ~30-n
-1 to 32a-n.

integrators 32b-1 to 32b-n for integrating the outputs of the preamplifiers 32a-1 to 32a-n, and the integrator 32
A multiplexer 34& for sequentially taking in the outputs of b-1 to 32b-n, an analog-to-digital converter 34b for converting the analog signal output from the multiplexer 34 to a digital number 16, and a a preamplifier 32C for amplifying the output of the light source light amount detector 17 to be detected; an analog-to-digital converter 34c for converting the analog signal output from the preamplifier 32c into a digital signal; and the analog-to-digital converter. vessels 34b and 3
For example, a central processing unit such as a microcomputer (hereinafter referred to as C
(referred to as PU) 36a, a memory 36b for storing programs, various constants, and calculation data in the CPU 36aK, a program counter 36c, and converting the digital number 100 output from the CPU 36a into an analog signal, It is comprised of a digital-to-analog converter 36d and h for outputting to an output device 38 consisting of an output display or the like.

The reason why the light source section 1sI is composed of two white light sources 14 arranged at the same angle with respect to the surface of the moving object 1O is to strongly irradiate the surface of the moving object 1O with uniform intensity. In addition, each white light source 14 is provided with a light source lens system 16 for irradiating the light emitting body image of the light source onto the surface of the moving object 10 because the light source is the same, the supply voltage is the same, and the irradiation intensity is the same. This is to make it stronger. By configuring this way, the influence of external light can be reduced (because it is possible to reduce the signal S/
Since the N ratio is improved and the supply voltage is lowered, the lamp life is extended (and power consumption is also reduced).In contrast, in conventional colorimeter devices.

When the light emitter image of the light source is formed on the irradiation surface, it directly
In order to prevent this from occurring as a measurement error, the irradiation by the light source was performed as scattered light or parallel light. As in the present invention,
By combining imaging illumination with a spectrometer that focuses the light using a focusing lens system.

Since the measurement data always gives the average value of the irradiated surface, the influence of uneven irradiation due to light source imaging can be avoided. As the white light source 14, a stable white light source such as a halogen lamp is used, and heat-resistant glass such as Pyrex or quartz is used to provide effective illumination. Further, in this embodiment, in order to correct the variation at of the light source intensity, a photodetector 17 (FIG. 3) is attached to the light source section 12, and the signal is sent via the analog-f signal converter 34c. By inputting the signal into the digital processing circuit 36, the signal intensity obtained by the detector 18 is corrected to eliminate measurement errors caused by fluctuations in light source intensity, and is used for monitoring the life of the light source.

In the detector 18, a diffraction grating 26 is used as a spectrometer, and it is combined with a slit 22 and a photodiode array 30.Since the dispersion angle of the diffraction grating 26 has a linear relationship with the wavelength, the slit 22 and the photodiode array 30 are used as a spectrometer. By using the array 30 in combination, the slit 2
After the reflected light from the measurement surface specified in 2 is spectrally divided,
This is because the light is incident on each channel on the photodiode array 30 at equal wavelength intervals, which is convenient for circuit design and manufacturing of the optical system and signal processing section.

For example, as a photodiode array 30.

When using a 35-element device, the geometrical arrangement of the optical system,
By selecting conditions such as slit width.

Using 31 elements out of all elements, visible wavelength range 400
Spectral intensities of ~700 g can be detected at wavelength intervals of 10π, and sufficient accuracy can be obtained for colorimetry.

The analog processing circuit 32 amplifies, for example, 31-point electrical signals obtained by the photodiode array 30 of the detector 18, and performs an integral operation to obtain the values of parameters necessary for one chromaticity calculation as electrical signals. . The reason why analog integration is performed here is 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 object to be measured as it moves over time, it is possible to maintain almost the continuity of the measurement. Therefore, the average chromaticity within a certain area determined by the optical system such as a slit system, the moving speed of the measurement object, the integration time, etc. can be obtained.
Naruga.

Even if you use a cheap microcomputer.

Since the processing time Fi can be reduced to 20 ms or less, the measurement surface does not become so wide. Furthermore, since the signal strength can be reduced, it has the advantage of being resistant to noise.

On the other hand, as suggested in JP-A No. 52-102780, for example, the signal from the photodiode array 30 etc. is directly input into a microcomputer to perform arithmetic processing such as integral calculation necessary for one chromaticity calculation. If all the calculations are performed using a microcomputer, there will be a disadvantage that the calculation time will be long and continuity will not be maintained when the target object moves at high speed.In addition, in order to eliminate this disadvantage,
An expensive computer on the scale of a minicomputer with high calculation speed is required.

Next, a description will be given of an apparatus for measuring the surface color tone of a color steel plate 400 in which the above embodiment is adopted.

In this device, as shown in FIG. 4 and FIG. is installed on the flat surface of a colored steel plate at a certain distance from the surface.When measuring, the light source is turned on and the detector 18
A processing circuit performs arithmetic processing on the signal obtained by the processing circuit, and outputs the resultant signal to an output device. In addition, the detection head 42t is equipped with a standard sample calibration device 46 that can be moved to perform measurements on a standard sample, and the measurement results are stored in the processing unit, so that the color difference between the color steel plate 40 and the measurement color steel plate 40 can be maintained. It is also possible to output a standard output, and an alarm can be sounded if there is a large deviation. Furthermore, if a scanning device 48 for remotely moving the colorimeter detection head 42 in the board width direction is installed,
It becomes possible to obtain color information over a wide range of the surface of the color steel plate 40.

We will explain the results of monitoring and measuring the color tone of an actual colored steel plate using a device like the one described below. Measurements were made using samples C3T (standard plate) and YS, which were subjected to chromate coloring treatment.
Regarding A (online steel plate), JI88730-
It was specified in the color difference display method of 1970. The color difference was determined using the Lab system. The direct measurement data of the spectral reflectance of the steel plate for each lQwi by this device is the chromate-colored steel plate C
8T and C8A, as shown in Fig. 6 and Fig. 7 respectively.
At A.

The results were as shown in FIGS. 8 and 9, respectively.

As the final output, the color difference as shown in Table 1 below was obtained, but the acceptance judgment of the color difference ΔE was determined by online monitoring when ΔE=1
．． It was confirmed that both samples (C8A and Y8) deviated from the specified value.

Table 1 Measurement Examples of Colored Steel Sheets The above device is one in which the present invention is applied to the measurement of the surface color tone of colored steel sheets. It is clear that the present invention can be similarly applied to measuring the surface color tone of stainless steel plates, electromagnetic steel plates, etc., detecting the whiteness of paper in the paper manufacturing process, detecting color shift in the printing process, etc.

As described above, according to the present invention, remote color measurement of the surface of a moving object can be performed with high precision and good responsiveness.

It is now possible to perform continuous product quality control.

Effective for improving yield. Moreover, it has excellent effects such as being expected to be applied to color tone control.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the overall configuration of an embodiment of the color measuring device for the surface of a moving object according to the present invention, FIG. 2 is a sectional view showing the optical system of the detector in the embodiment, and FIG. Similarly, FIG. 4 is a block diagram showing the configuration of an analog processing circuit, an analog-to-digital converter, and a digital processing circuit, in which the above embodiment is adopted. FIG. 5 is a side view showing the configuration around the detection head of the surface color tone measuring device for color steel plates. FIG. 6, which is also a plan view, was measured using the above device. FIG. 7 is a diagram showing the spectral reflectance of a standard plate that has been subjected to chromate coloring treatment, and FIG. FIG. 9 is a diagram showing the spectral reflectance of a standard plate coated with cream coloring, and FIG. 9 is a diagram showing the spectral reflectance of an online steel plate also coated with cream coloring. DESCRIPTION OF SYMBOLS 10... Moving object, 12... Light source part, 14... White light source, 16... Light source lens system, 18... Detector,
20...Condensing lens system, 22゛...Slit. 26... Diffraction grating-30... Photodiode array, 32... Analog processing circuit, 34... Analog-digital converter, 36... Digital processing circuit. 38...Output device. Agent Takaya Ron (and 1 other person) Figure 1 Figure 3 Figure 4 Figure 0 Figure 6 = 7 (nm) Figure 7 4004204404604805005205405
6051i+, Q 600 invasion 06406606a)
7ω□Liquid length (nm) Fig.8 10L length (nm)

Claims (2)

[Claims] (1) A light source unit that irradiates white light onto the surface of a moving object, a condensing lens system that images a part of the diffusely reflected light from the surface of the moving object, and an imaging plane of the condensing lens system. A slit or pinhole for defining the measurement area, a spectrometer for separating the light that has passed through the slit or pinhole, and a light that can simultaneously detect the intensity of the light of each wavelength separated by the spectrometer. a detection element; an analog processing circuit that performs analog integration processing on the electrical signal obtained by the photodetection element in an integration time corresponding to the signal processing time of the subsequent stage; and a digital processing circuit for obtaining color information on the surface of the moving object by means of an analog-to-digital converter for converting into digital signals, and a digital processing circuit for processing digital signals output from the analog-to-digital converter. A color measurement device for the surface of a moving object. (2) The light source section is composed of algebraic 4 light sources arranged at the same angle with respect to the surface of the moving object, and a light source lens for forming and irradiating a light emitting body image of the light source for each light source. A color measuring device for the surface of a moving object according to claim 1, further comprising a color measuring system.