WO2014118934A1

WO2014118934A1 - Film measuring device and film measuring method for battery electrode plate

Info

Publication number: WO2014118934A1
Application number: PCT/JP2013/052174
Authority: WO
Inventors: 健夫山田; 小林　正明; 良子西川; 信一西川
Original assignee: 株式会社ニレコ
Priority date: 2013-01-31
Filing date: 2013-01-31
Publication date: 2014-08-07
Also published as: JP5318303B1; JPWO2014118934A1

Abstract

This measuring device is provided with an optical system that includes a light source, an image capture unit, and a data processing unit. The measuring device is configured in such a manner that an object, which is a battery electrode plate comprising a substrate provided with a film on a surface, is illuminated by the optical system, an image of the illuminated object is acquired by the image capture unit, and the image of the object is processed by the data processing unit. The data processing unit is configured in such a manner as to determine, from data of the image of the object and data of an image of a premeasured quasi-blackbody, the reflection brightness of each pixel of the image of the object from which the internal reflection of the optical system has been eliminated, and uses the reflection brightness of each pixel from which the internal reflection of the optical system has been eliminated, to determine at least one of the thickness of the film, the density of the film, and the chromaticity value of the film.

Description

Battery electrode plate film measuring apparatus and film measuring method

The present invention relates to a measuring device for determining at least one of the thickness, density and chromaticity value of a film formed on a substrate surface of a battery electrode plate by using the reflected luminance of light irradiated on the battery electrode plate. And a measuring method.

For example, in the manufacturing process of a lithium ion storage battery, when manufacturing a positive or negative battery electrode plate, a functional material is applied to both sides of the base material and then pressed to roll as a positive electrode or negative electrode sheet (battery electrode plate) Rolled up into a shape. The positive electrode base material is an aluminum thin film, and the negative electrode base material is a copper thin film. The thickness of the thin film is 10 to 25 micrometers. Since the functional material contains various particulate materials and carbon particles or coated carbon, the color is close to black.

The functional material is mixed with water or an oily solvent, discharged from the slit die coat, and applied to one surface of the substrate. Thereafter, the functional material is fixed to the base material in a drying furnace, and the positive electrode or the negative electrode sheet is wound up as a roll. The sheet is rewound and applied to the other surface of the substrate in the same coating line, and then fixed in a drying furnace. Or you may perform the coating of both surfaces of a base material simultaneously. The thickness of the coating film on one side is 50 to 300 micrometers.

Conventionally, in the above process, a radiation film thickness meter is used for measuring the film thickness. However, the measurement by radiation has the following drawbacks.

First, it is difficult to separate and measure the film thickness on both sides of the substrate with radiation.

Second, the density of the film that changes due to press working cannot be measured with radiation. Since the measurement by radiation is essentially a measurement of the weight of the functional material, a change in density cannot be detected.

Third, since radiation is harmful to the human body, strict management is required and the burden of maintenance and management is large.

In addition to measurement by radiation, measurement of film thickness by a laser distance meter, a capacitive distance meter, an eddy current type distance meter, etc. has been studied, but none has been put into practical use.

On the other hand, a method of measuring the film thickness of the film on the base material of the battery electrode plate by measuring the reflection of light irradiated on the object has been developed (for example, Patent Document 1). However, since the functional material of the positive electrode and the negative electrode is almost black as described above, it is difficult to accurately measure the film thickness based on the color gradation. Furthermore, the density of the film cannot be measured by the method of Patent Document 1.

As described above, a measuring apparatus and a measuring method capable of accurately measuring at least one of the thickness, density and chromaticity value of the film on the substrate of the battery electrode plate have not been developed.

JP 2007-66821 A

Therefore, at least one of the thickness, density, and chromaticity value of the film formed on the substrate surface of the battery electrode plate is accurately measured by using the reflection luminance of the light irradiated on the battery electrode plate. There is a need for measuring devices and methods that can be used.

A measuring apparatus according to a first aspect of the present invention includes an optical system including a light source, an imaging unit, and a data processing unit, and irradiates a target which is a battery electrode plate made of a base material having a film on the surface by the optical system. The measurement apparatus is configured to acquire an image of the irradiated object by the imaging unit and process the image of the object by the data processing unit. The data processing unit obtains a reflection luminance obtained by removing reflection inside the optical system for each pixel of the target image from the data of the target image and the data of the quasi-black body image measured in advance. It is configured to obtain at least one of the thickness of the film, the density of the film, and the chromaticity value of the film using a reflection luminance obtained by removing reflection inside the optical system for the pixel.

According to the measuring apparatus of this aspect, the data processing unit performs reflection inside the optical system for each pixel of the target image from the target image data and the pre-measured quasi-blackbody image data. Since the removed reflection luminance is obtained and the reflection luminance obtained by removing the reflection inside the optical system for each pixel is used, even when the reflection luminance of the target is low, the film thickness, the film density, and At least one of the chromaticity values of the film can be determined.

According to the measuring apparatus according to the first embodiment of the first aspect of the present invention, the data processing unit is configured to obtain the density of the film using a standard deviation of the reflected luminance for each pixel. Has been.

According to the present embodiment, the film density can be obtained from the reflection luminance by utilizing the fact that the standard deviation of the reflection luminance has a predetermined relationship with the film density.

According to the measuring apparatus according to the second embodiment of the first aspect of the present invention, the data processing unit obtains the thickness of the film by using an average value of reflection luminance for each pixel. It is configured.

According to this embodiment, the film thickness can be obtained from the reflection luminance by utilizing the fact that the average value of the reflection luminance and the film thickness have a predetermined relationship.

In the measurement apparatus according to the third embodiment of the first aspect of the present invention, the imaging unit acquires the target color image, and the data processing unit reflects each pixel of the target color image. The luminance is used to determine the chromaticity value of the object.

According to the present embodiment, it is possible to grasp the change in the film characteristics from the change in the chromaticity value.

According to the measuring apparatus according to the fourth embodiment of the first aspect of the present invention, the optical system is configured to irradiate parallel light perpendicular to the surface of the object.

Therefore, it is easy to grasp the relationship between the reflected luminance and the film thickness, the film density, or the film chromaticity value.

According to the measuring apparatus according to the fifth embodiment of the first aspect of the present invention, the imaging unit acquires a two-dimensional image of the target.

According to the present embodiment, since the reflected luminance of each pixel of the target two-dimensional image is used, a large amount of data is obtained and the measurement accuracy is improved.

A measuring apparatus according to a second aspect of the present invention includes an optical system including a light source, an imaging unit, and a data processing unit, and irradiates a target which is a battery electrode plate made of a base material having a film on the surface by the optical system. The measurement apparatus is configured to acquire an image of the irradiated object by the imaging unit and process the image of the object by the data processing unit. The data processing unit is configured to obtain a reflection luminance for each pixel of the target image, and obtain a density of the film using a standard deviation of the reflection luminance for each pixel.

According to the measuring apparatus of this aspect, it is possible to obtain the film density from the reflection luminance by utilizing the fact that the standard deviation of the reflection luminance has a predetermined relationship with the film density.

The measurement method according to the third aspect of the present invention is a measurement method for measuring at least one of the thickness of the film, the density of the film, and the chromaticity value of the film provided on the surface of the substrate of the battery electrode plate. The measurement method includes the steps of: irradiating light to a target that is a battery electrode plate; acquiring the image of the target; and data of the target image and data of a quasi-blackbody for each pixel. Determining the reflection luminance of the object from which the reflection inside the optical system is removed, and using the reflection luminance of the object from which the reflection inside the optical system is removed for each pixel, the thickness of the film, Determining at least one of density and chromaticity value of the film.

According to the measurement method of this aspect, the reflection luminance of the object from which the reflection inside the optical system is removed for each pixel is obtained from the data of the object image and the data of the quasi-blackbody, Since at least one of the thickness of the film, the density of the film, and the chromaticity value of the film is obtained using the reflected brightness of the object from which the reflection inside the optical system is removed, the reflected brightness of the object Even if it is low, at least one of the film thickness, the film density, and the film chromaticity value can be obtained with high accuracy.

In the measurement method according to the first embodiment of the third aspect of the present invention, the density of the film is obtained using the standard deviation of the reflection luminance for each pixel.

In the measurement method according to the second embodiment of the third aspect of the present invention, the thickness of the film is obtained using the average value of the reflection luminance for each pixel.

In the measurement method according to the third embodiment of the third aspect of the present invention, a reflectance is obtained from reflected luminance using a calibration plate, and the thickness of the film, the density of the film, and the like are calculated using the reflectance. At least one of the chromaticity values of the film is determined.

According to this embodiment, traceable measurement is possible by using a calibration plate.

It is a figure which shows the structure of the measuring apparatus by one Embodiment of this invention. It is a figure which shows the image data which subtracted the data of the image of a cylindrical black body cavity from the image data of the film | membrane before a press (a brightness | luminance is 16 time). It is a figure which shows the image data which deducted the data of the image of a cylindrical black body cavity from the image data of "large diameter" (luminance is 16 times). It is a figure which shows the image data which deducted the data of the image of a cylindrical black body cavity from the image data of "No. 3" (luminance is 16 times). It is a figure which shows the image data which deducted the data of the image of a cylindrical black body cavity from the image data of "No. 4" (luminance is 16 times). It is a figure which shows the image data which deducted the data of the image of a cylindrical black body cavity from the image data of "No. 5" (luminance is 16 times). It is a figure which shows the image data which deducted the data of the image of a cylindrical black body cavity from the image data of "after press" (luminance is 8 times). It is a flowchart for demonstrating the method to measure the reflectance of a film | membrane with a measuring apparatus. It is a flowchart for demonstrating the method of calculating | requiring a reflectance and the standard deviation of a reflectance from measurement data. It is a figure which shows the reflection distribution of a low reflectance calibration board (SSL). For the positive electrode, before pressing, large diameter, no. 3, no. 4, no. 5 is a diagram showing measured values of average reflectances Rv (R%), Rv (G%), and Rv (B%) of six types of samples after pressing. For the positive electrode, before pressing, large diameter, no. 3, no. 4, no. 5 is a diagram showing measured values of standard deviation values σ · Rv (R%), σ · Rv (G%), and σ · Rv (B%) of six types of samples after pressing. For the positive electrode, before pressing, large diameter, no. 3, no. 4, no. 5. It is a figure which shows the measured value of the film thickness and density by the conventional measuring method of six types of samples after a press. It is a figure which shows the relationship between a film thickness and a reflectance about the sample of a positive electrode. It is a figure which shows the relationship between the density of a film | membrane, and the standard deviation of a reflectance about the sample of a positive electrode. For the negative electrode, before pressing, large diameter, no. 3, no. 4, no. 5 is a diagram showing measured values of average reflectances Rv (R%), Rv (G%), and Rv (B%) of six types of samples after pressing. For the negative electrode, before pressing, large diameter, no. 3, no. 4, no. 5 is a diagram showing measured values of standard deviation values σ · Rv (R%), σ · Rv (G%), and σ · Rv (B%) of six types of samples after pressing. For the negative electrode, before pressing, large diameter, no. 3, no. 4, no. 5. It is a figure which shows the measured value of the film thickness and density by the conventional measuring method of six types of samples after a press. It is a figure which shows the relationship between a film thickness and a reflectance about the sample of a negative electrode. It is a figure which shows the relationship between the density of a film | membrane, and the standard deviation of a reflectance about the sample of a negative electrode. Before pressing the negative electrode, large-diameter pressurization, No. 3 pressurization, no. 4 pressurization, no. It is a figure which shows chromaticity display after 5 pressurization and press. It is a figure which shows the chromaticity value coordinate before the press of a positive electrode sample and a negative electrode sample, and after a press.

FIG. 1 is a diagram showing a configuration of a measuring apparatus according to an embodiment of the present invention. The measuring apparatus 100 includes an optical system 101, an imaging unit 103, a data processing unit 105, and a data storage unit 107. The optical system 101 includes a light source 1011, a beam splitter 1013, and a telecentric lens 1015. The light source 1011 may be a light emitting diode (LED) light source having emission luminance in a wavelength range of 430 nanometers to 700 nanometers.

The imaging unit 103 may be a color video camera. The color video camera signal is divided into R, G, and B color signals, and numerical values from 0 to 4095 are stored as (R, G, B) values corresponding to each pixel by a 12-bit AD converter. The The number of pixels is horizontal X = 1600 on the screen and vertical Y = 1200 mm. (R, G, B) data is obtained for each point of (X, Y) as one screen data. With the optical system 101, the measurement visual field is about 10 × 12 mm, and the RGB information of a small spot of about 9 μm × 9 μm per pixel can be obtained. About 60,000 points of RGB data can be obtained when the final measurement area of the measurement field of view is about 2 mm x 3 mm.

After the light from the light source 1011 is reflected by the beam splitter 1013, it is irradiated as parallel light substantially perpendicular to the surface of the object 201 via the telecentric lens 1015. The light reflected by the surface of the target 201 passes through the telecentric lens 1015 and the beam splitter 1013 and reaches the imaging unit 103. The telecentric lens 1015 forms parallel light substantially perpendicular to the surface of the target 201 and sends only the light reflected in a direction substantially perpendicular to the surface of the target 201 to the imaging unit 103. In this way, a two-dimensional image of the target 201 irradiated by the light source 1011 is collected by the imaging unit 103. The collected two-dimensional image data is sent to the data processing unit 105 for processing. Data necessary for the processing is stored in the data storage unit 107 and used by the data processing unit 105 as necessary.

The functions of the data processing unit 105 and the data storage unit 107 will be described in detail later.

As a result of detailed observation of film samples of various thicknesses and densities while irradiating light on the positive electrode and the negative electrode of a lithium ion storage battery, the inventors changed the appearance of the film due to changes in the film thickness or density. I found out. This suggests the possibility of measuring the thickness or density of the film from the appearance image of the film.

By the way, as described above, the film contains a lot of carbon and the color thereof is almost black. This means that the reflection luminance of the film when irradiated with light is extremely low. Therefore, it is not easy to detect the change in appearance.

Therefore, the inventors have conceived that it is necessary to remove the reflection luminance inside the optical system from the image data of the film in order to accurately acquire the extremely low reflection luminance of the film. The reflection brightness inside the optical system can be obtained from an image of a cylindrical black body cavity as a quasi-black body. Therefore, by subtracting the image data of the cylindrical black body cavity from the data of the film image, the reflection luminance inside the optical system can be removed from the image data of the film.

FIGS. 2 to 7 are diagrams showing image data obtained by subtracting image data of a cylindrical black body cavity from image data of films of various thicknesses and densities. For the positive electrode, before pressing, large diameter, no. 3, no. 4, no. 5. Six types of samples after pressing were prepared. “Before pressing” is a sample that has not been pressurized after coating the membrane. “Large diameter” is a sample pressed with a cylinder having a diameter of 50 mm after coating a film. “No. 3”, “No. 4”, and “No. 5” are samples that were pressurized by changing the pressure with a cylinder having a diameter of 30 mm after coating the film. The applied pressure was increased in the order of “No. 3”, “No. 4”, and “No. 5”. “After pressing” is a sample after being pressed in the process. The pressurizing force of the five pressed samples is from “small diameter” to “large diameter”, “No. 3”, “No. 4”, “No. 5”, and “after pressing”.

FIG. 2 is an image in which the brightness of the “before press” sample is 16 times.

FIG. 3 is an image in which the brightness of the “large diameter” sample is 16 times.

FIG. 4 is an image in which the luminance of the sample of “No. 3” is increased 16 times.

FIG. 5 is an image in which the brightness of the sample of “No. 4” is increased 16 times.

FIG. 6 is an image in which the brightness of the sample of “No. 5” is increased 16 times.

FIG. 7 is an image in which the brightness of the “after press” sample is 8 times.

The reason why the luminance is increased 16 times in the images shown in FIGS. 2 to 6 is to facilitate visual observation. The reason why the image shown in FIG. 7 is 8 times instead of 16 times is to prevent saturation.

According to FIG. 2 to FIG. 7, by observing with the naked eye an image obtained by subtracting the image data of the cylindrical black body cavity from the image data of the film, the pressurization situation is different, and therefore the thickness and density of the film Can distinguish the appearance of different membranes.

Therefore, the inventors have determined the reflection luminance of the film from the image obtained by subtracting the image data of the cylindrical black body cavity from the image data of the film. Furthermore, in order to ensure traceability, the reflectance was determined from the reflected luminance.

As described above, the imaging unit 103 collects an image of reflected light reflected in a direction substantially perpendicular to the surface of the object 201 of parallel light irradiated in a direction substantially perpendicular to the surface of the object 201.

FIG. 8 is a flowchart for explaining a method of measuring the reflectance of the film by the measuring apparatus 100.

In step S010 in FIG. 8, the brightness of the light source is set. Set a sufficient brightness considering the low reflectance of the object. A white LED (light emitting diode) light source was used as the light source. Specifically, it is model MCEC-CW8 (maximum rated current 0.15A, for high power coaxial lighting for applications MML) manufactured by Moritex Corporation.

In step S020 in FIG. 8, the shutter time of the camera is set. A sample that is considered to have the highest reflectance is selected from the samples to be measured, and a shutter time at which the R, G, and B values of the video signal of the camera 103 are not saturated is selected. In this embodiment, the shutter time during sample measurement is 1 millisecond.

In step S030 of FIG. 8, the measurement apparatus 100 measures the reflection luminance of the low-reflectance calibration plate (SSL) having a mirror surface. A shutter time during which the values of R, G, and B are not saturated when SSL is measured is selected and measured. In this embodiment, the shutter time during SSL measurement is set to 0.357 msec. The reflected luminance of SSL was R = 2415.5, G = 3310.7, and B = 3752.2. The reflected luminance of SSL is described in column A of Table 1 described later.

FIG. 10 is a diagram showing the reflectance distribution of the low reflectance calibration plate (SSL). The horizontal axis in FIG. 10 indicates the wavelength, and the vertical axis in FIG. 10 indicates the reflectance. FIG. 10 shows a spectral sensitivity curve obtained by multiplying the spectrum of the LED light source and the sensitivity distribution of R, G, and B.

In step S040 of FIG. 8, the measurement apparatus 100 measures the reflection luminance of the cylindrical black body cavity as a quasi-black body. The shutter time was 0.357 msec. The measured reflection luminance of the cylindrical black body cavity corresponds to the reflection luminance inside the optical system 101 including the light source 101. The reflection luminance of the cylindrical black body cavity is described in column B of Table 1.

In step S050 in FIG. 8, the luminance value with a reflectance of 1% when the shutter time is 1 millisecond is calculated.

Table 1 is a table for explaining a calculation procedure of luminance values (R, G, and B values) with a reflectance of 1% when the shutter time is 1 millisecond. The numerical values in the columns labeled R, G, and B in Table 1 represent the values (counts) of R, G, and B.

The column A in Table 1 shows the reflected luminance (R, G, B) of SSL when the shutter time is 0.357 msec. Column B in Table 1 shows the reflection luminance (R, G, B) of the cylindrical black body cavity when the shutter time is 0.357 msec. The column C in Table 1 shows the reflectivity (R, G, B) of SSL expressed in%. (AB) / C represents the value obtained by subtracting the value in the B column from the value in the A column and dividing by the value in the C column for each of R, G, and B, and setting the shutter time to 0.357 msec. This is a value of (R, G, B) corresponding to 1% reflectance in the case. D is a numerical value obtained by multiplying (AB) / C by 1 / 0.357 for each of R, G, and B, and corresponds to 1% reflectance when the shutter time is 1 msec (R , G, B). In this way, the luminance value (R, G, B values) with a reflectance of 1% when the shutter time is 1 msec can be calculated.

In step S060 of FIG. 8, the reflectance of the target is obtained. First, the reflection time (R, G, B) of the cylindrical black body cavity is measured by the measuring apparatus 100 with a shutter time of 1 millisecond. Next, the reflection time (R, G, B) of the sample after pressing the positive electrode is measured by the measuring apparatus 100 with a shutter time of 1 millisecond.

Table 2 is a table | surface which shows the procedure which calculates | requires the reflectance of the sample after the positive electrode press. The numerical values in the columns labeled R, G, and B in Table 1 represent the values (counts) of R, G, and B.

Column E in Table 2 shows the reflection luminance (R, G, B) of the cylindrical black body cavity when the shutter time is 1 millisecond. The column F in Table 2 shows the reflection luminance (R, G, B) of the sample after pressing the positive electrode when the shutter time is 1 millisecond. FE is a numerical value obtained by subtracting the value in the E column from the value in the F column for each of R, G, and B, and corresponds to the true reflected luminance of the sample after pressing the positive electrode. H is a value obtained by dividing the value of FE by the value of D in Table 1 for each of R, G, and B. The reflectivity Rv (R%) and Rv (G%) of the sample after pressing the positive electrode ), Rv (B%).

Table 3 is a table | surface which shows the procedure which calculates | requires the reflectance of the sample before the positive electrode press.

The reflectance before positive electrode pressing is calculated as Rv (R%) = 0.0091%, Rv (G%) = 0.0086%, Rv (B%) = 0.0093%. Compared to reflectivity after positive electrode pressing, it is as small as 1/10 or less.

In Table 3, R is E = 820.6, F = 833.3, and the difference is very small at 12.7. The reason why this numerical value is reliable is because the AD converter of the color video camera has 12 bits and a high resolution of 0 to 4,095. In addition, taking an average value of about 60,000 pixels also contributes.

FIG. 9 is a flowchart for explaining a method of obtaining the reflectance and the standard deviation of the reflectance from the measurement data. Each step in FIG. 9 is performed by the data processing unit 105.

In step S1010 of FIG. 9, the two-dimensional data (D1) of the measured value of the reflection luminance (R, G, B) of the cylindrical black body cavity is stored in the data storage unit 107. D1 is data corresponding to 201 pixels × 301 pixels at the center of the image.

In step S1020 of FIG. 9, the two-dimensional data (D2) of the measured value of the reflection luminance (R, G, B) of the sample after pressing the positive electrode is stored in the data storage unit 107. D2 is data corresponding to 201 pixels × 301 pixels at the center of the image.

In step S1030 in FIG. 9, the two-dimensional difference data (D2-D1) is stored in the data storage unit 107. D1-D2 is data corresponding to 201 pixels × 301 pixels at the center of the image.

In step S1040 of FIG. 9, the average values R, G, B and standard deviation values σ · R, σ · G, σ · B of the two-dimensional difference data (D2-D1) are calculated.

In step S1050 of FIG. 9, the average reflectance Rv (R%), Rv (G%), Rv (B%) of each pixel and the standard of the reflectance of each pixel are obtained using the 1% reflectance already obtained. Deviation values σ · Rv (R%), σ · Rv (G%), and σ · Rv (B%) are calculated.

In step S1060 in FIG. 9, chromaticity values are obtained from the average reflectances Rv (R%), Rv (G%), and Rv (B%). The chromaticity value will be described later.

Fig. 11 shows the positive electrode before pressing, large diameter, no. 3, no. 4, no. 5 is a diagram showing measured values of average reflectances Rv (R%), Rv (G%), and Rv (B%) of six types of samples after pressing. The measured values of average reflectance are from small to large, before pressing, large diameter, No. 3, no. 4, no. 5. The order after pressing. In FIG. 11 and subsequent figures, “inner”, “middle”, and “outer” indicate measured values at three locations in the radial direction of each sample.

FIG. 12 shows the positive electrode before pressing, large diameter, No. 3, no. 4, no. 5 is a diagram showing measured values of standard deviation values σ · Rv (R%), σ · Rv (G%), and σ · Rv (B%) of six types of samples after pressing. The measurement values of the standard deviation values are from small to large, before pressing, large diameter, No. 3, no. 4, no. 5. The order after pressing.

Fig. 13 shows the positive electrode before pressing, large diameter, No. 3, no. 4, no. 5. It is a figure which shows the measured value of the film thickness and density by the conventional measuring method of six types of samples after a press. The vertical axis in FIG. 13 indicates the film thickness (left scale) and the film density (right scale). The film thickness was determined by measuring the thickness of the sample consisting of the substrate and the film with a precision contact dial gauge and subtracting the known thickness of the substrate. The density was calculated by measuring the weight of a circular sample having a diameter of 100 mm with an electronic balance, subtracting the known weight of the substrate to obtain the weight of the film, and using the measured value of the film thickness.

FIG. 14 is a diagram showing the relationship between the film thickness and the reflectance of the positive electrode sample. The horizontal axis in FIG. 14 indicates the logarithmic value of the reflectance, and the vertical axis indicates the film thickness. FIG. 14 was prepared from the data of the measured values of average reflectance shown in FIG. 11 and the data of the measured values of film thickness by the conventional measuring method shown in FIG.

Since there is a gap inside the film, the light irradiated on the film surface is reflected on the film surface, enters the film, and reaches the substrate (aluminum in the case of the positive electrode) while being irregularly reflected inside the gap. It is reflected, returns to the film surface, and is scattered and emitted from the film surface into the air. The amount of reflected light returning from within the film is absorbed by the film in the same manner as radiation, and therefore decreases as the film thickness increases. Therefore, the relationship between the film thickness and the reflectance as shown in FIG. 14 is obtained.

∙ Since the surface before pressing is almost close to the diffusing surface, the reflectivity from the surface itself is small. However, the surface after pressing and pressing is partially glossy, and the reflected light to be measured is the sum of reflection from the surface and reflection from within the film. Therefore, the approximate expression was created by dividing into two groups of a thick film region and a thin film region.

In this way, a first-order approximation of the film thickness d is obtained by LOG (Rv-R), LOG (Rv-G), and LOG (Rv-B). The degree of correlation R ² varies depending on R, G, and B, but a high value of 0.92 or higher was obtained. It can be expected that the degree of correlation further improves by increasing the number of data.

An example of an approximate expression using LOG (Rv−G) having a high degree of correlation in two film thickness regions in FIG. 14 is shown below.
Thick area: d = -46.419 LOG (Rv-G) -2.1635 R ² = 0.9743 (1)
Thin area: d = -12.74 LOG (Rv-G2) +55.105 R ² = 0.9713 (2)
The coefficient of the first-order approximation formula is the same as that of radiation or the like, if the film material is different. Therefore, it is necessary to create a calibration curve for each material of the film.

FIG. 15 is a diagram showing the relationship between the film density and the standard deviation of the reflectance for the positive electrode sample. The horizontal axis of FIG. 15 indicates the standard deviation of the reflectance, and the vertical axis indicates the density of the film. FIG. 15 was created from the data of the measured value of the standard deviation of the reflectance shown in FIG. 12 and the data of the measured value of the film density by the conventional measuring method shown in FIG.

When the density is small, the value of σ · Rv (R, G, B%) is small, and when the density is large, the value of σ · Rv (R, G, B%) is large. Although the surface gloss is increased by pressing, since the uniform pressing is not performed, the σ of the vertical reflectance increases for all the colors of R, G, and B.

In this case, the relationship between the film density ρ and σ · Rv (R%), σ · Rv (G%), and σ · Rv (B%) can be approximated by a linear expression as shown in FIG. , correlation R ² is as high as about 0.93. The approximate expression of Rv (G%) having the highest degree of correlation is shown below.

ρ = 18.188σ · Rv (G%) + 2.7643 R ² = 0.9356 Formula (3)
Since the coefficient of the approximate expression at this time is influenced by the battery material component and the film thickness range even with the same positive electrode, an approximate expression with higher accuracy can be obtained by increasing the number of samples and the number of data.

Thus, according to the inventors' new knowledge, there is a high correlation between the density of the film and the standard deviation of the reflectance, and the density of the film can be obtained from the standard deviation of the reflectance.

FIG. 16 shows the negative electrode before pressing, large diameter, no. 3, no. 4, no. 5 is a diagram showing measured values of average reflectances Rv (R%), Rv (G%), and Rv (B%) of six types of samples after pressing. The measured values of average reflectance are from small to large, before pressing, large diameter, No. 3, no. 4, no. 5. The order after pressing.

According to FIG. 11 showing the measured value of the average reflectance of the positive electrode sample, the average reflectance before pressing is about 0.01%, and the reflectance after pressing is 0.15% to 0.18%. On the other hand, according to FIG. 16 which shows the measured value of the average reflectance of the negative electrode sample, the average reflectance before pressing is about 0.019%, and the reflectance after pressing is about 0.09%. Thus, the change in average reflectance before and after pressing is much larger in the case of the positive electrode. This is presumably because the material of the positive electrode substrate and the film is different from the material of the negative electrode substrate and the film.

FIG. 17 shows the negative electrode before pressing, large diameter, No. 3, no. 4, no. 5 is a diagram showing measured values of standard deviation values σ · Rv (R%), σ · Rv (G%), and σ · Rv (B%) of six types of samples after pressing. The measurement values of the standard deviation values are from small to large, before pressing, large diameter, No. 3, no. 4, no. 5. The order after pressing.

FIG. 18 shows the negative electrode before pressing, large diameter, No. 3, no. 4, no. 5. It is a figure which shows the measured value of the film thickness and density by the conventional measuring method of six types of samples after a press. The vertical axis in FIG. 18 indicates the film thickness (left scale) and the film density (right scale). The method for measuring the film thickness and the film density is the same as in FIG.

FIG. 19 is a diagram showing the relationship between the film thickness and the reflectance of the negative electrode sample. The horizontal axis in FIG. 19 indicates the logarithmic value of the reflectance, and the vertical axis indicates the film thickness. FIG. 19 was created from the data of the measured values of average reflectance shown in FIG. 16 and the data of the measured values of film thickness by the conventional measuring method shown in FIG.

As in the case of FIG. 14, approximate equations were created by dividing into two groups of a thick film region and a thin film region.

Correlation R ^2, the correlation degree R ² is about 0.92 in the film thickness is thicker regions, 0.97 in thin region. It can be expected that the degree of correlation further improves by increasing the number of data.

FIG. 20 is a diagram showing the relationship between the film density and the standard deviation of the reflectance for the negative electrode sample. The horizontal axis of FIG. 20 indicates the standard deviation of the reflectance, and the vertical axis indicates the density of the film. FIG. 20 was created from the measurement data of the standard deviation of reflectance shown in FIG. 17 and the measurement data of the film density by the conventional measurement method shown in FIG.

In this case, the relationship between the film density ρ and σ · Rv (R%), σ · Rv (G%), and σ · Rv (B%) can be approximated by a linear expression as shown in FIG. , correlation R ² is as high as about 0.91. By increasing the number of samples of the same material and the number of data, a more accurate approximate expression can be obtained.

As shown in FIG. 14 and FIG. 19, it was found that the film thickness d can be measured using a first-order approximation of the logarithmic value of the average reflectance Rv (R, G, B) for both positive and negative electrodes.

15 and 20, it was found that the density ρ can be measured by the linear expression of the standard deviation value σ · Rv (R, G, B) of the reflectance for both positive and negative electrodes.

According to the measuring apparatus and measuring method of the present invention, it is necessary to create a calibration curve for each battery material and film thickness region, but the film thickness and film density on both surfaces are measured without being affected by the opposite surface. be able to. When a film is applied on both sides, it is impossible to measure the film thickness on one side and measure the density of the film with a conventional measurement method including radiation measurement.

What is important in the manufacturing process of the positive electrode and the negative electrode is to uniformly apply the battery material particle group to the base material and obtain a uniform porosity after drying. If the battery material component is non-uniform in the width direction or the porosity distribution is non-uniform, variations in battery performance will occur. Further, if there is a difference in the liquid concentration distribution at the time of ejection, a difference in the porosity distribution occurs, and similarly, the performance as a battery varies.

The battery material is almost black, but the color will change if the concentration ratio of the constituent materials changes. In fact, when FIG. 11 and FIG. 16 are observed, the magnitude relationship among the average reflectances Rv (R%), Rv (G%), and Rv (B%) varies from sample to sample. Therefore, it was decided to measure the color value of the sample.

Specifically, with reference to the display method of tristimulus values X, Y, and Z of the reflected color tristimulus value method obtained by normal color value measurement, the chromaticity value display of RGB reflectance is obtained from the following formula did.

In the XYZ value method, color values are expressed in Yxy. The chromaticity values x and y are expressed by the following equations.
x = X / (X + Y + Z) (4)
y = Y / (X + Y + Z) (5)
z = Z / (X + Y + Z) (6)

Since a color video camera is used in the present invention, chromaticity values are defined from the RGB signals. The calculation method of the chromaticity value is shown below.
X = Rv (R), Y = Rv (G), Z = Rv (B) (7)

Let Grb represent the color video color.
r = Rv (R) / Σ {Rv (R, G, B) (8)
g = Rv (G) / Σ {Rv (R, G, B) (9)
b = Rv (B) / Σ {Rv (R, G, B) (10)

The chromaticity value is (r, b) because it is more intuitive to see if the long wavelength side (R) and short wavelength side (B) increase in the reflectance distribution of the black material. This is because it was judged. Similar to the Yxy method, the chromaticity value may be (r, g).

FIG. 21 shows the negative electrode before pressing, large diameter, no. 3, no. 4, no. 5 is a diagram showing chromaticity display after pressing. The horizontal axis of FIG. 21 indicates r obtained from Expression (8), and the vertical axis indicates b obtained from Expression (10).

FIG. 21 also shows the average value for each state. The average chromaticity values before and after pressing are (r = 0.334, b = 0.362) and (0.330, 0.331), which are clearly different. Also, by pressing, the average value of chromaticity values is as follows: before pressing → large diameter pressing → No. 3 pressing → No. 4 pressing → No. 5 pressing → after pressing and (r, b) coordinates. The center point moves without intersecting.

This means that the hue changes uniformly from before to after pressing.

After drying the coating process, monitor the chromaticity coordinate change and if this value changes significantly,
Information that uniform coating is not completed can be provided.

FIG. 22 is a diagram showing chromaticity value coordinates before and after pressing of the positive electrode sample and the negative electrode sample. The horizontal axis of FIG. 22 represents r obtained from the equation (8), and the vertical axis represents b obtained from the equation (10). According to FIG. 22, the chromaticity values before and after pressing are clearly different for the positive electrode sample and the negative electrode sample. Therefore, the press state of the positive electrode and the negative electrode can be measured by the measuring apparatus of the present invention.

Since the measuring apparatus of the present embodiment performs two-dimensional image measurement, it is possible to perform measurement immediately after ejection of intermittent coating and immediately after stopping. In this case, the measuring device is preferably installed immediately after coating. In addition, even in the wet state, there is a high possibility that the calculation method shown above can be applied.

Also, when the surface of aluminum or copper as a base material is oxidized, the performance as an electrode deteriorates. What is necessary is just to measure the reflective color of an uncoated part about the color measurement of a base material. In this case, since the reflectance is high, a high reflectance calibration plate is required. In addition, it is necessary to adjust the shutter time according to the target. Conversion to reflectance can be performed based on the concept shown in Tables 1 and 2. The same applies to the chromaticity value. Thus, the measuring apparatus of this embodiment can be used also for the measurement of a base material.

In the above-described embodiment, the measurement was performed by calculating the relationship between the film thickness and the film density by converting the reflection luminance into the reflectance using a calibration plate. However, depending on the purpose of use, the measurement may be performed by obtaining the relationship between the reflected luminance, the film thickness, and the film density. In this case, a calibration plate is not necessary.

Further, in the above-described embodiment, since the target is black and the reflection luminance is low, the process of removing the reflection inside the optical system is performed using a quasi-black body. However, it is not necessary to use a quasi-black body in the case of an object having a high reflection luminance. Even in such a case, the measurement can be performed using the relationship between the average value of the reflected luminance and the film thickness and the relationship between the standard deviation of the reflected luminance and the density.

The measuring device of this embodiment is installed on one side or both sides of the coating line and the press line after coating, moved in the width direction by the driving device, and the film thickness, density, and chromaticity value in the width direction and the line running direction. It is also possible to make measurements. In that case, it is desirable that the cylindrical black body cavity and the reflectance calibration plate be installed outside the line and calibrated at regular intervals. This can be done automatically by creating an automatic sequence.

The measuring device of this embodiment can also be used as an off-line device.

The camera used in the measurement apparatus of the present embodiment reduces the time for capturing one image when the number of horizontal scanning lines is reduced, and can measure in a short cycle. Currently, the vertical direction of the screen is 1,200 lines, so when the measurement line is 200 lines, one cycle is shortened to 1/6. Normal measurement is 30Hz, but 180Hz measurement is possible, and more responsive measurement is possible.

Claims

An optical system including a light source, an imaging unit, and a data processing unit are provided. The optical system irradiates a target, which is a battery electrode plate made of a base material having a film on the surface, and captures an image of the irradiated target A measuring device configured to be acquired by a processing unit and to process the target image by the data processing unit,
The data processing unit obtains a reflection luminance obtained by removing reflection inside the optical system for each pixel of the target image from the data of the target image and the data of the quasi-black body image measured in advance. A measurement apparatus configured to obtain at least one of the thickness of the film, the density of the film, and the chromaticity value of the film using a reflection luminance obtained by removing reflection inside the optical system for the pixel.
The measurement apparatus according to claim 1, wherein the data processing unit is configured to obtain the density of the film using a standard deviation of reflection luminance for each pixel.
The measurement apparatus according to claim 1 or 2, wherein the data processing unit is configured to obtain the thickness of the film using an average value of reflection luminance for each pixel.
The imaging unit is configured to acquire an image of the target color, and the data processing unit is configured to obtain a chromaticity value of the target using a reflection luminance of each pixel of the target color image. The measuring apparatus according to claim 1.
The measuring apparatus according to any one of claims 1 to 4, wherein the optical system is configured to irradiate parallel light perpendicularly to the surface of the object.
The measuring apparatus according to claim 1, wherein the imaging unit acquires a two-dimensional image of the target.
An optical system including a light source, an imaging unit, and a data processing unit are provided. The optical system irradiates a target, which is a battery electrode plate made of a base material having a film on the surface, and captures an image of the irradiated target A measuring device configured to be acquired by a processing unit and to process the target image by the data processing unit,
The measurement apparatus configured to obtain a reflection luminance for each pixel of the target image and obtain a density of the film using a standard deviation of the reflection luminance for each pixel.
A measurement method for measuring at least one of a film thickness, a film density, and a film chromaticity value provided on a surface of a substrate of a battery electrode plate,
Irradiating light to an object that is a battery electrode plate;
Obtaining an image of the object;
From the data of the target image and the data of the quasi-blackbody image, obtaining the reflection luminance of the target with the reflection inside the optical system removed for each pixel;
Determining at least one of the thickness of the film, the density of the film, and the chromaticity value of the film using the reflected luminance of the object from which reflection inside the optical system for each pixel is removed; and Including measurement methods.
The measurement method according to claim 8, wherein the density of the film is obtained by using a standard deviation of reflected luminance for each pixel.
The measurement method according to claim 8 or 9, wherein the thickness of the film is obtained using an average value of reflection luminance for each pixel.
11. The reflectivity is obtained from reflection luminance using a calibration plate, and at least one of the thickness of the film, the density of the film, and the chromaticity value of the film is obtained using the reflectivity. The measuring method in any one.