Defect inspection method and defect inspection device

Abstract

In this invention, in a process of manufacturing a secondary battery using a flat layer member formed on an opaque base material, a defect in the layer member is inspected using a captured image obtained by imaging the layer member at a facing position. The electrode layer is irradiated with first color light at a first incident angle. The layer member is irradiated with second color light different from the first color light at a second incident angle larger than the first incident angle. A captured image is acquired by imaging the layer member simultaneously irradiated with the first color light and the second color light. A defect in the layer member is detected on the basis of a color of a bright spot and a shadow included in the captured image.

Description

Defect inspection method and defect inspection apparatus

[0001] This invention relates to a defect inspection method and a defect inspection apparatus for inspecting defects in the electrode layer during the manufacturing process of secondary batteries.

[0002] JP6860098B1 discloses an image inspection device that uses images of an object to inspect for defects such as scratches, cracks, chips, dents, and deformations formed on the surface of the object. In particular, this image inspection device uses a dome-shaped lighting fixture consisting of multiple lighting elements to photograph the object with multiple lighting patterns that differ in direction, wavelength, or intensity, allowing the user to search for the optimal lighting pattern that makes it easier to find defects.

[0003] In the manufacturing process of secondary batteries, defect inspection (visual inspection) is performed on the electrode layer, for example, using captured images. The electrode layer may have defects such as pinholes, aggregation of electrode material, contamination or adhesion of foreign matter, and metal deposition. Of these, for example, the lighting conditions that are most effective for detecting pinholes differ from those that are most effective for detecting irregularities caused by the aggregation of electrode material. Therefore, defect inspection of the electrode layer requires changing the lighting conditions and imaging the electrode layer at least twice, which has resulted in a time-consuming defect inspection process.

[0004] The present invention aims to provide a defect inspection method and defect inspection apparatus that can detect pinhole defects and surface irregularities in a single imaging (single image).

[0005] One aspect of the present invention is a defect inspection method for inspecting defects in an electrode layer during the process of manufacturing a secondary battery having a flat electrode layer formed on an opaque substrate, using an image of the electrode layer captured at a frontal position. In this defect inspection method, the electrode layer is irradiated with a first color light at a first incidence angle, and then irradiated with a second color light different from the first color light at a second incidence angle greater than the first incidence angle. An image is obtained by capturing the electrode layer irradiated with the first and second color lights simultaneously, and defects in the electrode layer are detected based on the color of bright spots and shading contained in the captured image.

[0006] Figure 1 is a block diagram showing the configuration of the defect inspection device. Figure 2 is an explanatory diagram showing the layout of the first light source, the second light source, and the imaging device. Figure 3 is an explanatory diagram showing the imaging method using the first light source and the first color image. Figure 4 is an explanatory diagram showing the imaging method using the second light source and the second color image. Figure 5 is an explanatory diagram showing the captured image. Figure 6 is a flowchart related to defect inspection. Figure 7 is an explanatory diagram showing the layout of the light source in a modified example.

[0007] Embodiments of the present invention will be described below with reference to the drawings.

[0008] Figure 1 is a block diagram showing the configuration of the defect inspection device 100. As shown in Figure 1, the defect inspection device 100 is a device that captures an image of the external appearance of the workpiece 10 and uses the captured image to detect defects in the object being inspected.

[0009] The workpiece 10 is an intermediate product (inspection item) that includes a portion to be inspected for defects. In this embodiment, the defect inspection device 100 detects defects in a flat electrode layer 11 (see Figure 2, etc.) that constitutes a secondary battery, for example, during the manufacturing process of a secondary battery such as an all-solid-state battery. For this reason, in this embodiment, the workpiece 10 consists of an electrode layer 11 and a flat base material 12 that supports the electrode layer 11.

[0010] The base material 12 is a member that supports the electrode layer 11 and other layers that constitute a secondary battery during the process of forming such layers. The base material 12 can become a component of a secondary battery together with the electrode layer 11 and other layers. However, the electrode layer 11 and other layers may be separated (peeled off) from the base material 12 and used in a secondary battery, and the base material 12 may not become a component of the final secondary battery. Furthermore, the base material 12 is at least flat and substantially opaque. In this embodiment, the base material 12 is formed from a metal foil such as aluminum or copper, and functions as a current collector in a secondary battery. For this reason, the base material 12 is usually opaque and has a metallic luster. Accordingly, in this embodiment, the base material 12 of the workpiece 10 is a flat and opaque metal foil.

[0011] The electrode layer 11 is a layered or thin-film component (hereinafter referred to as a layered component) that constitutes a secondary battery, and is particularly a part that constitutes the electrode of the secondary battery. The electrode layer 11 is subject to defect inspection by the defect inspection device 100. However, the defect inspection device 100 can perform defect inspections not only on the electrode layer 11 containing the active material, but also on the solid electrolyte layer and the intermediate layer provided between the electrode layer 11 and the solid electrolyte layer (for example, the negative electrode intermediate layer provided between the negative electrode layer and the solid electrolyte layer). In other words, the object of inspection by the defect inspection device 100 is each layered component that constitutes the secondary battery, or a composite (laminated) of each layered component. In the following, as an example, the electrode layer 11 will be considered to be the object of substantial defect inspection.

[0012] In this embodiment, the electrode layer 11 is formed by, for example, applying a slurry of electrode materials such as an active material, a conductive additive, a binder, and a solid electrolyte to a substrate 12 in a uniform thickness and drying it. The electrode layer 11 may contain particles containing one or more types of metals. For example, the electrode layer 11 may contain particles containing silver (Ag), gold (Au), palladium (Pd), silicon (Si), aluminum (Al), bismuth (Bi), magnesium (Mg), tin (Sn), zinc (Zn), gallium (Ga), germanium (Ge), indium (In), or antimony (Sb).

[0013] Various defects can occur in the electrode layer 11. Specifically, the electrode layer 11 may have defects such as pinholes 26 where the substrate 12 is exposed (see Figure 3, etc.), irregularities 27 caused by aggregation of electrode material (see Figure 3, etc.), deposition of metal particles, or contamination or adhesion of foreign matter. The defect inspection device 100 simultaneously detects these defects, particularly pinholes 26 and irregularities 27, in a single image (one captured image).

[0014] The workpiece 10 is automatically transported to the defect inspection device 100 by the transport device 13. The transport device 13 is composed of, for example, a conveyor or transport rollers. The defect inspection device 100 is located at a predetermined imaging position P ｉｍｇ (See Figure 2) The workpiece 10 that has been transported is imaged.

[0015] The defect inspection device 100 includes a first light source 21, a second light source 22, an imaging device 24, and an image analysis device 25.

[0016] The first light source 21 is an illumination light source that irradiates the electrode layer 11 of the workpiece 10 at the imaging position P ｉｍｇ with illumination light of a first color (hereinafter referred to as the first color light λ １ ). The first color is one of the plurality of colors of pixels (color filters) that the imaging device 24 has. Therefore, the first color light λ １ substantially only responds to one of the plurality of colors of pixels that the imaging device 24 has.

[0017] The second light source 22 is an illumination light source that irradiates the electrode layer 11 of the workpiece 10 at the imaging position P ｉｍｇ with illumination light of a second color (hereinafter referred to as the second color light λ ２ ). The second color is one of the plurality of colors of pixels that the imaging device 24 has. However, the second color has a color (wavelength) different from the first color. Therefore, the second color light λ ２ substantially only responds to one of the plurality of colors of pixels that is different from the first color light λ １ . Briefly speaking, the second color light λ ２ is illumination light with a color (peak wavelength or wavelength band) different from the first color light λ <00.org / legalcode> １

[0018] The imaging device 24 is at the imaging position P <00.org / legalcode> ｉｍｇ and captures the electrode layer 11 in a state where the first color light λ １ and the second color light λ ２ １ is reflected or scattered light of the first color light λ ２ is an image captured by the reflected or scattered light of the second color light λ

[0019] The imaging device 24 images one workpiece 10 (electrode layer 11) once. That is, the imaging device 24 acquires one image 30 for each workpiece 10 (electrode layer 11). Also, the defect inspection device 100 has only one imaging device 24. Therefore, in the defect inspection device 100, the entire electrode layer 11 is imaged in one pass using a single imaging device 24.

[0020] The imaging device 24 may be composed of one or more cameras, such as line scan cameras or area scan cameras. However, it is preferable that the imaging device 24 be composed of one camera. In this embodiment, the imaging device 24 is assumed to be composed of one area scan camera.

[0021] The imaging device 24 has pixels of multiple colors. For example, the imaging device 24 is composed of primary color pixels of blue (B), green (G), and red (R). In addition, the imaging device 24 may be composed of complementary color pixels of cyan (C), magenta (M), and yellow (Y). Furthermore, the imaging device 24 may include pixels that are sensitive to ultraviolet light or infrared light. However, the imaging device 24 shall have at least two types of pixels whose sensitive light wavelength bands (colors) do not substantially overlap.

[0022] In this embodiment, the imaging device 24 has blue (B), green (G), and red (R) pixels. The blue pixels are, for example, pixels that are sensitive to light in a wavelength band of approximately 490 nm or less. The green pixels are, for example, pixels that are sensitive to light in a wavelength band of approximately 490 nm to approximately 600 nm. The red pixels are, for example, pixels that are sensitive to light in a wavelength band of approximately 600 nm or more.

[0023] Therefore, the first color light λ １ This is the illumination light of one of the BGR colors, and the second color light λ ２ This is the first color light λ of the BGR. １ It is a single-color illumination light, different from the first color light λ. １ When it is blue light, the second color light λ ２ This is green light or red light. The first color light λ １ When it is green light, the second color light λ２ This is blue light or red light. The first color light λ １ When the light is red, the second color light λ ２ This is blue light or green light. In this embodiment, the first color light λ １ This is blue light, and the second color light λ ２ Assume that it is green light.

[0024] The image analysis device 25 inspects for defects in the electrode layer 11 by analyzing the captured image 30 acquired by the imaging device 24. In other words, the image analysis device 25 detects defects in the electrode layer 11 using the captured image 30. In particular, in this embodiment, if the image analysis device 25 detects a defect, it can identify the type of defect.

[0025] Specifically, the image analysis device 25 detects defects in the electrode layer 11 based on the bright spots and shadows contained in the captured image 30. In particular, in this embodiment, the image analysis device 25 detects defects based on the color of the bright spots and the presence or absence of shadows contained in the captured image 30. As a result, the image analysis device 25 can not only detect all defects in the electrode layer 11 without fail, but also identify their type.

[0026] Figure 2 is an explanatory diagram showing the layout of the first light source 21, the second light source 22, and the imaging device 24.

[0027] As shown in Figure 2, the imaging device 24 is positioned at imaging position P ｉｍｇ The imaging device 24 is positioned directly opposite the workpiece 10 (electrode layer 11) located therein. That is, the imaging device 24 is positioned along its optical axis (hereinafter referred to as the imaging optical axis L ｉｍｇ The electrodes are arranged so as to be parallel to the normal of the electrode layer 11. ｉｍｇ It is vertical. In this embodiment, the imaging device 24 is positioned so that the entire electrode layer 11 fits within its field of view 35 (angle of view).

[0028] The first light source 21 is located at imaging position P ｉｍｇ With respect to the workpiece 10 (electrode layer 11) located there, the first incident angle θ １ Then the first color light λ １ It is positioned to irradiate with the normal of the electrode layer 11 and the first color light λ. １The optical axis (hereinafter referred to as the first illumination optical axis L) １ The angle formed by ( ) is the first angle of incidence θ １ In this embodiment, the imaging optical axis L ｉｍｇ Since it is parallel to the normal of the electrode layer 11, the imaging optical axis L ｉｍｇ and the first illumination optical axis L １ The angle formed is the first angle of incidence θ １ That is the case.

[0029] 1st angle of incidence θ １ This is between 0 degrees and 45 degrees (0 ≤ θ). １ Preferably, the temperature is ≤45, and 0 degrees or more and 30 degrees or less (0 ≤ θ １ It is more preferable that the first incidence angle θ is ≤ 30. １ This is between 0 degrees and 15 degrees (0 ≤ θ). １ It is particularly preferable that ≤ 15. That is, the first light source 21 emits the first color light λ １ The light source is positioned to irradiate the electrode layer 11 approximately perpendicularly. In this embodiment, the first incident angle θ １ It is approximately 0 degrees (θ １ ≈0).

[0030] The second light source 22 is located at imaging position P ｉｍｇ With respect to the workpiece 10 (electrode layer 11) located there, the second incidence angle θ ２ Then the second color light λ ２ It is positioned to irradiate with the normal to the electrode layer 11 and the second color light λ. ２ The optical axis (hereinafter referred to as the second illumination optical axis L) ２ The angle formed by ( ) is the second angle of incidence θ ２ In this embodiment, the imaging optical axis L ｉｍｇ Since it is parallel to the normal of the electrode layer 11, the imaging optical axis L ｉｍｇ and the second illumination optical axis L ２ The angle formed is the second angle of incidence θ ２ That is the case.

[0031] Second angle of incidence θ ２ This is between 45 degrees and 90 degrees (45 ≤ θ). ２ Preferably, the angle is 70 degrees or more and 90 degrees or less (70 ≤ θ). ２ It is more preferable that the second incidence angle θ is ≤ 90. ２ is 85 degrees or more and 90 degrees or less (85 ≤ θ)２ It is particularly preferable that the second light source 22 emits the second color light λ ２ The light is positioned to irradiate the electrode layer 11 in a manner that is approximately parallel to it. In this embodiment, the second incident angle θ ２ The angle is approximately 85 degrees (θ ２ ≈85).

[0032] In addition, the first light source 21 and the second light source 22 have a first incidence angle θ １ and the second incidence angle θ ２ The sum of the two is at least 45 degrees (45 ≤ θ) １ +θ ２ They are arranged such that ). In other words, the first light source 21 and the second light source 22 are aligned along the first illumination optical axis L １ and the second illumination optical axis L ２ The two are arranged such that the angle between them is 45 degrees or more. The first light source 21 and the second light source 22 are arranged at a first incident angle θ １ and the second incidence angle θ ２ The sum of the θ is 60 degrees (60 ≤ θ) １ +θ ２ It is more preferable that they be arranged such that the first incidence angle θ １ and the second incidence angle θ ２ The sum of the angles is 75 degrees (75 ≤ θ) １ +θ ２ It is particularly preferable that they be arranged such that ). In this embodiment, the first incident angle θ １ and the second incidence angle θ ２ The sum is approximately 85 degrees (θ １ +θ ２ It is approximately 85.

[0033] Furthermore, the first light source 21 and the second light source 22 are defined as the first incident angle θ mentioned above. １ and second angle of incidence θ ２ The following conditions must be met, and the device can be positioned at any location within a range that does not obstruct the field of view 35 of the imaging device 24. In this embodiment, the transport direction of the workpiece 10 is the X direction, and the imaging position P ｉｍｇ Within the plane of the workpiece 10 located at the position P, the direction perpendicular to the X direction is defined as the Y direction, and the imaging position P ｉｍｇ The normal direction of the workpiece 10 located there is defined as the Z direction. The first light source 21 emits the first color light λ from the positive side in the X direction (downstream side in the transport direction). １is arranged to irradiate, and the second light source 22 irradiates the second color light λ from the negative side in the X direction (the upstream side in the conveyance direction). ２ is arranged to irradiate. In FIG. 2, the conveyance direction of the workpiece 10 is indicated by a white arrow.

[0034] Also, in the present embodiment, the first color light λ １ and the second color light λ ２ are both parallel lights (collimated lights). Therefore, the workpiece 10 (electrode layer 11) is illuminated particularly uniformly by the first color light λ １ and the second color light λ ２ . However, when it can be considered that the workpiece 10 (electrode layer 11) is substantially uniformly illuminated by the first color light λ １ and the second color light λ ２ , the first color light λ １ and the second color light λ ２ may be diffused lights.

[0035] FIG. 3 is an explanatory diagram showing an imaging method using the first light source 21 and a first color image 31. FIG. 3(A) is an explanatory diagram showing an imaging method using the first light source 21. FIG. 3(B) is a schematic diagram of the first color image 31.

[0036] As shown in FIG. 3(A), the first light source 21 irradiates the workpiece 10 with the first color light λ １ at a first incident angle θ １ . Therefore, the first color light λ １ incides on the electrode layer 11 substantially perpendicularly. Therefore, the first color light λ １ is reflected or scattered on the surface of the electrode layer 11 and incides on the imaging device 24. In particular, since the surface of the electrode layer 11 is flat, in particular, the reflected light of the first color light λ １ easily incides on the imaging device 24. Therefore, the imaging method using the first light source 21 is basically an imaging method for imaging the electrode layer 11 by the reflected light on the surface of the electrode layer 11.

[0037] When there is a defect of the pinhole 26 in the electrode layer 11, the first color light λ １The light is reflected by the substrate 12 exposed by the pinhole 26 and incident on the imaging device 24. As mentioned above, the substrate 12 is made of metal foil and has a higher reflectivity than the electrode layer 11, so the first color light λ incident on the pinhole 26 is reflected. １ This is the first color light λ incident on the electrode layer 11. １ More than that enters the imaging device 24.

[0038] If the electrode layer 11 has defects such as irregularities 27, the first color light λ １ The light is reflected or scattered by the irregularities 27 and incident on the imaging device 24. However, as mentioned above, the irregularities 27 are formed of aggregates of electrode material, and their reflectivity is the same as that of the electrode layer 11.

[0039] From these observations, as shown in Figure 3(B), in the first-color image 31, the pinhole 26 appears as a distinct bright spot against the background 28, which is an image of the defect-free area. That is, the first-color light λ １ The first angle of incidence θ １ The illumination conditions for irradiating the electrode layer 11 are such that the pinholes 26 can be easily detected. However, in the first color image 31, the irregularities 27 are almost indistinguishable from the background 28. That is, the first color light λ １ The first angle of incidence θ １ Under the illumination conditions used to irradiate the electrode layer 11, it is difficult to reliably and reliably detect the irregularities 27 without any omissions.

[0040] Figure 4 is an explanatory diagram showing the imaging method using the second light source 22 and the second color image 32. Figure 4(A) is an explanatory diagram showing the imaging method using the second light source 22. Figure 4(B) is a schematic diagram of the second color image 32.

[0041] As shown in Figure 4(A), the second light source 22 emits a second color light λ to the workpiece 10. ２ The second incidence angle θ ２ Since it is irradiated with, the first color light λ １ In comparison, the second color light λ ２ The light is incident on the electrode layer 11 approximately parallel to it. Therefore, the second color light λ ２ Almost no directly reflected light enters the imaging device 24. However, the second color light λ on the surface of the electrode layer 11 ２The scattered light from the second light source 22 is incident on the imaging device 24. Therefore, the imaging method using the second light source 22 is basically an imaging method that images the electrode layer 11 using scattered light on the surface of the electrode layer 11.

[0042] If there is a pinhole 26 defect in the electrode layer 11, the second color light λ ２ The light is reflected by the substrate 12 exposed by the pinhole 26, but this reflected light from the substrate 12 is unlikely to enter the imaging device 24.

[0043] If the electrode layer 11 has defects such as irregularities 27, the second color light λ ２ The light is scattered according to the shape of the irregularities 27. Also, when there are irregularities 27, the second color light λ is behind the irregularities 27. ２ It is difficult to reach. For this reason, scattered light is less likely to occur in the area behind the uneven surface 27, and the scattered light in the area behind the uneven surface 27 is less than the scattered light from the other flat areas.

[0044] From these observations, as shown in Figure 4(B), in the second-color image 32, the contours of the reliefs 27 are emphasized against the background 28. Furthermore, shading 29 is formed behind the reliefs 27. That is, the second-color light λ ２ The second incidence angle θ ２ The illumination conditions for irradiating the electrode layer 11 are such that the irregularities 27 are easily detectable. However, in the second-color image 32, the pinholes 26 are almost indistinguishable from the background 28. That is, the second-color light λ ２ The second incidence angle θ ２ Under the illumination conditions used to irradiate the electrode layer 11, it is difficult to reliably and reliably detect pinholes 26 without any leaks.

[0045] Figure 5 is an explanatory diagram showing the captured image 30. As described above, the captured image 30 of the defect inspection device 100 is a color image in which the first color image 31 is assigned to the first color channel and the second color image 32 is assigned to the second color channel. Therefore, as shown in Figure 5, in the captured image 30, the pinhole 26 appears as a bright spot of the first color, or a bright spot having a mixed color of the first and second colors. In addition, in the captured image 30, the contours of the irregularities 27 are emphasized, and shading 29 is also added.

[0046] First color light λ １ or second-color light λ２ It depends on the intensity (light quantity) and the sensitivity of each color pixel, but for example, the first color light λ １ This is blue light, and the second color light λ ２ When the light is green, the pinhole 26 becomes a blue bright spot. The uneven surface 27 as a whole exhibits a green color that is roughly the same as the background 28 (the part without defects), but the shading 29 and outlines appear more clearly compared to the background 28.

[0047] Therefore, the image analysis device 25 can simultaneously detect pinholes 26 and irregularities 27 using a single captured image 30. Furthermore, the image analysis device 25 can distinguish pinholes 26 by the color of bright spots and irregularities 27 by shading 29 and contours (especially shading 29).

[0048] Furthermore, defects caused by metal particles or foreign matter appear as bright spots in both the first color image 31 and the second color image 32. Therefore, in the captured image 30, metal particles and foreign matter appear as bright spots. For example, the first color light λ １ This is blue light, and the second color light λ ２ When the light is green, metal particles and foreign objects appear as bright spots with a cyan color that is almost white in the captured image 30. Therefore, the image analysis device 25 can detect (distinguish) the pinholes 26 and irregularities 27 separately from the metal particles or foreign objects.

[0049] Figure 6 is a flowchart related to defect inspection. As shown in Figure 6, in step S10, the workpiece 10 is at imaging position P ｉｍｇ It is transported to the following location. Specifically, a slurry of electrode material is applied onto the substrate 12 and dried. This creates a workpiece 10 with an electrode layer 11 formed on the substrate 12. The workpiece 10 thus created is then transported by the transport device 13 to the imaging position P ｉｍｇ It is transported to the imaging position P. More specifically, the workpiece 10 is transported to the imaging position P. ｉｍｇ It passes through.

[0050] In step S11, the first light source 21 is positioned at imaging position P ｉｍｇ First color light λ is emitted from the workpiece 10 located there. １ The first incidence angle θ １The light source is used to irradiate the image at position P. In step S12, the second light source 22 is used to irradiate the image at position P. ｉｍｇ Second-color light λ is emitted from the workpiece 10 located there. ２ Irradiate the area. That is, during transport, the imaging position P ｉｍｇ The electrode layer 11 of the workpiece 10 that passes through receives the first color light λ １ and the second color light λ ２ The two are irradiated substantially simultaneously. However, the electrode layer 11 is irradiated with the first color light λ １ The first angle of incidence is θ １ Irradiated with the second color light λ ２ The second incidence angle θ ２ It is irradiated with light.

[0051] In step S13, the imaging device 24 moves to imaging position P ｉｍｇ The electrode layer 11 of the workpiece 10 located there is imaged. Here, the first incidence angle θ １ The first color light λ １ and the second incidence angle θ ２ The second color light λ ２ The entire electrode layer 11, which is simultaneously irradiated, is imaged in a single pass by a single imaging device 24.

[0052] In step S14, the image analysis device 25 detects the pinholes 26 using the captured image 30 acquired by the imaging device 24. Specifically, the image analysis device 25 detects the pinholes 26 in the electrode layer 11 based on the color of the bright spots in the captured image 30. In this embodiment, the first color light λ １ This is blue light, and the second color light λ ２ Because the light is green, the image analysis device 25 identifies the area that appears as a blue bright spot as a pinhole 26.

[0053] In step S15, the image analysis device 25 uses the same captured image 30 used to detect the pinhole 26 to detect the irregularities 27 of the electrode layer 11 based on the shading 29 and contours (especially the shading 29) of the image in the captured image 30. Specifically, the image analysis device 25 determines that the areas accompanied by shading 29 are irregularities 27. In this embodiment, the first color light λ １ This is blue light, and the second color light λ ２Since the light is green, the image analysis device 25 determines that the green area with a contour accompanied by shading 29 is an uneven surface 27.

[0054] As described above, the detection of pinholes 26 and irregularities 27 is performed using a single captured image 30. Therefore, the detection of pinholes 26 and irregularities 27 is performed substantially simultaneously. In addition, the image analysis device 25 can detect defects caused by metal particles or foreign matter, in addition to pinholes 26 and irregularities 27, using a single captured image 30. In this embodiment, the image analysis device 25 identifies bright, almost white spots as metal particles or foreign matter.

[0055] As described above, the defect inspection device 100 has a first incidence angle θ with respect to the electrode layer 11. １ Then the first color light λ １ The light is irradiated, and at the same time, the first incident angle θ １ A second incidence angle θ that is larger than ２ Then, the second color light λ is different from the first color light. ２ The electrode layer 11, which is the object to be inspected, is imaged by irradiating it with light. As a result, the defect inspection device 100 can detect pinholes 26 and irregularities 27 in a single image (one image 30). Consequently, the defect inspection device 100 can quickly inspect the electrode layer 11 for defects while the workpiece 10 is being transported.

[0056] For example, to detect a pinhole 26, it is desirable to illuminate the electrode layer 11 with illumination light approximately perpendicular to it, but in this case, it is difficult to detect irregularities 27. On the other hand, to detect irregularities 27, it is desirable to illuminate the electrode layer 11 with illumination light from an oblique direction (especially an approximately parallel direction), but in this case, it is difficult to detect a pinhole 26. Furthermore, if illumination light is irradiated from two directions, perpendicular and oblique, to the electrode layer 11 in order to simultaneously detect both pinholes 26 and irregularities 27, the pinholes 26 become the same color as the background 28 and are difficult to distinguish, and the irregularities 27 become difficult to distinguish due to the fading of the shadows 29 and the outlines. In other words, simply irradiating with illumination light from two directions makes it difficult to detect both pinholes 26 and irregularities 27. Therefore, in defect inspection of the electrode layer 11, it is usually necessary to image the electrode layer 11 with illumination conditions for detecting pinholes 26, and then re-image the electrode layer 11 with illumination conditions for detecting irregularities 27.

[0057] In contrast, the defect inspection device 100 of this embodiment uses two lights with different colors (wavelengths) and angles of incidence to the electrode layer 11 in the imaging device 24 to image the electrode layer 11. As a result, in the image 30 acquired by the defect inspection device 100, pinholes 26 appear as bright spots of the first color, and irregularities 27 are emphasized as images of the second color accompanied by shading 29. That is, in a single image 30, the defect inspection device 100 can distinguish pinholes 26 based on the color of the bright spots and distinguish irregularities 27 based on the shading 29. As a result, since imaging of the electrode layer 11 is only required once, the defect inspection device 100 can perform defect inspection of the electrode layer 11 more quickly than conventional devices. Furthermore, the defect inspection device 100 can perform defect inspection of the electrode layer 11 while the workpiece 10 is substantially moving.

[0058] Furthermore, when using a dome-shaped lighting fixture, as in the image inspection device described in prior art documents, even if the color (wavelength) and incident angle of the illumination light are changed, the curvature of the illumination element and diffuse reflection within the dome mean that very small irregularities 27 on the electrode layer 11 are hardly shadowed 29. Therefore, it is not possible to detect the irregularities 27 on the electrode layer 11 with this dome-shaped lighting fixture.

[0059] Furthermore, if a dome-shaped lighting fixture is used, as in the image inspection apparatus described in the prior art documents, the size of this lighting fixture will be several times larger than the object being inspected. Even if the size of the object being inspected is, for example, only a few tens of millimeters square, a huge dome-shaped lighting fixture with an outer dimension of several hundred millimeters in diameter would be required. Since the electrode layer 11 is, for example, only a few hundred millimeters square, if a dome-shaped lighting fixture is used to inspect defects in the electrode layer 11, its outer dimension would be on the order of several meters in diameter, making the lighting fixture extremely large. In this respect, the defect inspection apparatus 100 of this embodiment can be compactly constructed, with a size substantially similar to the workpiece 10 (electrode layer 11) that is the object being inspected.

[0060] [Modified Example] In the above embodiment, the defect inspection device 100 uses the first color light λ １ The first angle of incidence θ １ The first light source 21 and the second color light λ are irradiated by ２ The second incidence angle θ ２ The device uses two illumination light sources, including a second light source 22 that irradiates with the first light source 21 and the second light source 22, but is not limited to this. The defect inspection device 100 may further include illumination light sources other than the first light source 21 and the second light source 22.

[0061] Figure 7 is an explanatory diagram showing the layout of the light sources in a modified example. As shown in Figure 7, the defect inspection device 100 may further include a third light source 23 in addition to the first light source 21 and the second light source 22.

[0062] The third light source 23 emits the first color light λ １ and second-color light λ ２ From a different direction, the first color light λ １ and second-color light λ ２ A third color of illumination light that is different from (hereinafter referred to as third color light λ) ３ (This refers to) imaging position P ｉｍｇ The third light source 23 is directed to the workpiece 10 (electrode layer 11) located at imaging position P. ｉｍｇ With respect to the workpiece 10 located at the third incidence angle θ ３ The third color light λ ３ It is positioned so that the light is incident on it. That is, the normal to the electrode layer 11 and the third color light λ ３ The optical axis (hereinafter referred to as the third illumination optical axis L) ３The angle formed by ( ) is the third angle of incidence θ ３ This is the imaging optical axis L. ｉｍｇ When the normal to the electrode layer 11 is parallel, the imaging optical axis L ｉｍｇ and the third illumination optical axis L ３ The angle formed is the third angle of incidence θ. ３ That is the case.

[0063] The third color is one of the multiple colored pixels of the imaging device 24. However, the third color has a different color from the first and second colors. Therefore, the third color light λ ３ This refers to the first color light λ, which is substantially one of the multiple color pixels of the imaging device 24. １ and second-color light λ ２ It is sensitive only to pixels that are different from the third color light λ. ３ This is the first color light λ １ and second-color light λ ２ This refers to illumination light with different colors (peak wavelength or wavelength band). For example, if the imaging device 24 has primary color pixels of blue (B), green (G), and red (R), the first color light λ １ and second-color light λ ２ When these are blue light and green light respectively, the third color light λ ３ It is red light.

[0064] Here, the third color light λ ３ This is the first color light λ １ and second-color light λ ２ Similarly, it is parallel light (collimated light). Therefore, the third color light λ ３ As a result, the workpiece 10 (electrode layer 11) is illuminated particularly uniformly. However, the third color light λ ３ If the workpiece 10 (electrode layer 11) can be considered to be illuminated substantially uniformly by this, then the third color light λ ３ It may also be diffuse light.

[0065] Third angle of incidence θ ３ It does not physically interfere with the first light source 21, the second light source 22, and the imaging device 24, and the third color light λ ３ The range is arbitrarily determined within a range that allows for substantially uniform illumination of the workpiece 10 (electrode layer 11).

[0066] However, the third angle of incidence θ ３This is at least the first incidence angle θ １ and second angle of incidence θ ２ It is preferable to set it to a different angle. That is, θ ３ ≠θ １ and θ ３ ≠θ ２ It is preferable that this is the case. And the third incidence angle θ ３ The first angle of incidence θ １ Larger than the second incidence angle θ ２ It is preferable that it be smaller than (θ １ <θ ３ <θ ２ ). Also, the third color light λ ３ When a shadow is cast behind the uneven surface 27, the third incidence angle θ ３ This is the third color light λ ３ The shadows of the uneven surface 27 caused by the second color light λ ２ The shape is determined so as not to encompass the entirety of the shading 29 of the uneven surface 27.

[0067] Thus, when the defect inspection device 100 includes a third light source 23 in addition to the first light source 21 and the second light source 22, the captured image 30 is composed of the first color light λ １ , second color light λ ２ , and the third color light λ ３ This is obtained by imaging the electrode layer 11 that is simultaneously irradiated with the first color λ. This image 30 is obtained by imaging the electrode layer 11 that is irradiated with the first color λ. １ The corresponding first-color image 31 is assigned to the first-color channel, and the second-color light λ ２ The corresponding second color image 32 is assigned to the second color channel, and the third color light λ ３ The image is obtained by assigning a third color image (not shown) corresponding to the third color to the third color channel. In this captured image 30, the pinhole 26, the unevenness 27, the background 28, and the shadows 29 each have different colors. For example, the first color light λ １ This is blue light, and the second color light λ ２ This is green light, and the third color light λ ３When the light source is red, in the captured image 30, for example, the shadows 29 will be red or magenta against a generally yellow background 28. In other words, by introducing the third light source 23, the shadows 29 are colored and emphasized. As a result, the image analysis device 25 can more easily and accurately detect (distinguish) the surface irregularities 27 with a single capture (one captured image 30).

[0068] In the above embodiment and modified defect inspection apparatus 100, various types of light sources can be used as the first light source 21, the second light source 22, and the third light source 23. For example, the first light source 21, the second light source 22, and the third light source 23 can all be made up of bar-type (rod-shaped) lighting fixtures. The first light source 21 can be made up of a ring-type (annular) lighting fixture installed around the imaging device 24.

[0069] In the above embodiment and modified defect inspection apparatus 100, various types of light sources can be used as the first light source 21, the second light source 22, and the third light source 23. For example, the first light source 21, the second light source 22, and the third light source 23 can be configured to extract illumination light of the required color from light emitted by, for example, an LED (Light Emitting Diode), a fluorescent lamp, an incandescent lamp, or a mercury lamp.

[0070] In the above embodiment and modified defect inspection apparatus 100, the first illumination optical axis L １ , second illumination optical axis L ２ , third illumination optical axis L ３ , and the imaging optical axis L ｉｍｇ These can all be bent as needed by using mirrors, semi-transparent mirrors, or prisms.

[0071] In the above embodiment and modified defect inspection apparatus 100, for the sake of explanation, the first color light λ １ , second color light λ ２ , and the third color light λ ３ However, each corresponds to one color of a pixel in the imaging device 24, but is not limited to this. First color light λ １ , second color light λ ２ , and the third color light λ ３The wavelength bands may be such that they are sensitive to multiple color pixels among the pixels of the imaging device 24, provided that they have different wavelength bands. For example, the first color light λ １ Let be white light, and second color light λ ２ The illumination light can be blue light, green light, or red light. In this case as well, the defect inspection device 100 can detect pinholes 26 and irregularities 27 using a single captured image 30, similar to the embodiment described above.

[0072] In the above embodiment and modified defect inspection apparatus 100, the first color light λ １ and second-color light λ ２ It is preferable that the light source be selected from blue light, green light, or red light. In this case, the defect inspection device 100 can be easily configured using the most common imaging device 24 having BGR pixels. And in this way the first color light λ １ and second-color light λ ２ When selecting from blue light, green light, or red light, the first color light λ １ or second-color light λ ２ It is preferable that one of the light sources is blue light. This is because the shorter the wavelength of the illumination light, the more easily it is reflected or scattered by the pinholes 26 and the uneven surfaces 27, making it easier to obtain a clear image of the pinholes 26 and the uneven surfaces 27.

[0073] As described above, the defect inspection method according to the above embodiment and its modifications is a defect inspection method that inspects defects in a layer member (11) using an image 30 taken of the layer member (11) in a frontal position during the process of manufacturing a secondary battery using a flat layer member (e.g., an electrode layer 11) formed on an opaque substrate 12. In this defect inspection method, the layer member (11) is subjected to a first incidence angle θ １ Then the first color light λ １ The light is irradiated onto the layer member (11) at a first incident angle θ １ A second incidence angle θ that is larger than ２ Then, the first color light λ １ The second color light λ is different from the second color light λ ２ Irradiate with the first color light λ １ and second-color light λ ２By imaging the layer member (11) that is simultaneously irradiated, an image 30 is obtained, and defects in the layer member (11) are detected based on the color of the bright spots and the shading 29 contained in this image 30.

[0074] Thus, the first angle of incidence θ １ The first color light λ １ and the second incidence angle θ ２ The second color light λ ２ According to the defect inspection method that uses an image 30 captured by simultaneously irradiating and capturing, in a single image 30, pinholes 26 are emphasized by the color of the bright spots, and irregularities 27 are emphasized by the deliberately added shading 29. Therefore, with this defect inspection method, pinholes 26 and irregularities 27 can be detected in a single image. Furthermore, with this defect inspection method, pinholes 26, irregularities 27, and metal particles or foreign matter can be distinguished separately in a single image. Consequently, with this defect inspection method, defect inspection of the layer member (11) can be performed in a shorter time compared to conventional defect inspection devices that require multiple images.

[0075] In the above embodiment and modified defect inspection method, the first incidence angle θ １ and the second incidence angle θ ２ The sum of the angles is 45 degrees or more.

[0076] Thus, the first angle of incidence θ １ and the second incidence angle θ ２ By making the sum of these angles at least 45 degrees, the color of the pinhole 26 and the shading 29 of the unevenness 27 become clearer in the captured image 30. Therefore, the pinhole 26 and the unevenness 27 can be easily and accurately detected.

[0077] In the above embodiment and modified defect inspection method, the first incidence angle θ １ The angle is between 0 and 45 degrees, and the second incidence angle θ ２ It is between 45 degrees and 90 degrees.

[0078] Thus, the first angle of incidence θ １ The angle is set to 0 degrees or more and 45 degrees or less, and the first color light λ １When the light is shone approximately perpendicularly to the layer member (11), the image and color of the pinhole 26 tend to appear clearly in the captured image 30. Then, the second incident angle θ ２ The angle is set to 45 degrees or more and 90 degrees or less, and the second color light λ ２ When the light is shone approximately parallel to the layer member (11), the shadows 29 of the irregularities 27 tend to appear clearly in the captured image 30. For this reason, the first incident angle θ １ The angle is set to be between 0 degrees and 45 degrees, and the second incidence angle θ ２ If the angle is set to between 45 and 90 degrees, pinholes 26 and uneven surfaces 27 are particularly easy to detect in a single image 30.

[0079] In the defect inspection method according to the above embodiment and modified example, the first color light λ １ and second-color light λ ２ The light source can be selected from blue, green, or red light.

[0080] Thus, the first color light λ １ and second-color light λ ２ By selecting blue light, green light, or red light, the defect inspection device 100 can be easily constructed using the most common imaging device 24 having BGR pixels.

[0081] In the defect inspection method according to the above embodiment and modified example, the first color light λ １ or second-color light λ ２ That is blue light.

[0082] Thus, the first color light λ １ and second-color light λ ２ When selecting from blue light, green light, or red light, the first color light λ １ or second-color light λ ２ By using blue light for one of the two, it is easier to obtain a clear image of the pinhole 26 and the uneven surface 27.

[0083] In the defect inspection method according to the above embodiment and modified example, the layer member (11) is imaged while the workpiece 10, which consists of a base material 12 and a layer member (11), is being transported.

[0084] In this way, by imaging the layer member (11) while the workpiece 10 is being transported, defect inspection of the layer member (11) can be smoothly performed within the series of steps in the secondary battery manufacturing process. In other words, accurate defect inspection of the layer member (11) can be performed at the stage when the layer member (11) is formed, without extending the cycle time (manufacturing pitch) related to secondary battery manufacturing. Furthermore, the yield in secondary battery manufacturing is also improved.

[0085] In the defect inspection method according to the above embodiment and modified example, the layer member (11) is imaged while the workpiece 10 is moving during transport.

[0086] In this way, by imaging while the workpiece 10 is moving, defect inspection of the layer members (11) can be performed substantially continuously for each workpiece 10 as they are produced, without delaying (or pausing) the transport of the workpiece 10. Therefore, accurate defect inspection of the layer members (11) can be performed without extending the cycle time.

[0087] In the defect inspection method according to the above embodiment and modified example, the first color light λ １ and second-color light λ ２ The light is directed at the entire layer member (11), and the entire layer member (11) is imaged in a single pass by one imaging device 24.

[0088] Thus, the first color light λ １ and second-color light λ ２ By irradiating the entire layer member (11) and imaging the entire layer member (11) in one pass with a single imaging device 24, pinholes 26 and irregularities 27 can be detected easily and accurately, especially in a short time. Specifically, when using multiple imaging devices, synchronization processing and alignment of images obtained from each imaging device are necessary. However, as described above, if the entire layer member (11) is imaged in one pass with a single imaging device 24, synchronization processing and image alignment are unnecessary. For this reason, pinholes 26 and irregularities 27 can be detected easily and accurately, especially in a short time.

[0089] In the defect inspection method according to the above embodiment and modified example, the first color light λ １and second-color light λ ２ These are parallel rays.

[0090] Thus, the first color light λ １ and second-color light λ ２ If the light is parallel, the layer member (11) to be inspected can be illuminated uniformly. Therefore, pinholes 26 and irregularities 27 can be detected without fail, regardless of their position on the layer member (11). In particular, the second color light λ ２ If the light source is parallel, clear shadows 29 are easily created on the uneven surfaces 27. This makes it easier to detect the uneven surfaces 27.

[0091] In the defect inspection method according to the above embodiment and modified example, the first color light λ １ Based on the bright spots having the corresponding colors, the pinholes 26 are identified, and based on the shading 29, the irregularities 27 are identified.

[0092] In this way, by referring to the color of the bright spots that appear in the captured image 30, the pinholes 26 can be easily and accurately detected. Furthermore, by using the shading 29, the irregularities 27 can be easily and accurately detected.

[0093] In the defect inspection method according to the above embodiment and modified example, the first color light λ １ and second-color light λ ２ From a different direction, the first color light λ １ and second-color light λ ２ A different third color of light λ ３ Irradiate with the first color light λ １ , second color light λ ２ , and the third color light λ ３ By imaging the layer member (11) that is simultaneously irradiated, an imaged image 30 is obtained.

[0094] Thus, when imaging the layer member (11), the first color light λ １ and second-color light λ ２ In addition, the third color light λ ３ When both are irradiated simultaneously, the shadows 29 of the irregularities 27 are colored and emphasized in the captured image 30. As a result, the irregularities 27 can be easily and accurately detected.

[0095] The defect inspection apparatus according to the above embodiment and its modified form is a defect inspection apparatus 100 that inspects defects in a layer member (e.g., an electrode layer 11) formed on an opaque substrate 12 during the process of manufacturing a secondary battery using an image 30 of the layer member (11) taken at a frontal position. This defect inspection apparatus 100 applies a first incidence angle θ to the layer member (11). １ Then the first color light λ １ A first light source 21 that irradiates the layer member (11) with respect to the first incident angle θ １ A second incidence angle θ that is larger than ２ Then, the first color light λ １ The second color light λ is different from the second color light λ ２ A second light source 22 that irradiates with light, and a first color light λ positioned directly opposite the layer member (11) １ and second-color light λ ２ The system includes an imaging device 24 that acquires an image 30 by imaging a layer member (11) that is simultaneously irradiated, and an image analysis device 25 that detects defects in the layer member (11) based on the color of bright spots and shading 29 contained in the image 30.

[0096] Thus, the first angle of incidence θ １ The first color light λ １ and the second incidence angle θ ２ The second color light λ ２ In the defect inspection device 100, which uses an image 30 captured by simultaneously irradiating and capturing two elements, in a single image 30, pinholes 26 are emphasized by the color of the bright spots, and irregularities 27 are emphasized by the deliberately added shading 29. Therefore, this defect inspection device 100 can detect pinholes 26 and irregularities 27 in a single image. Furthermore, this defect inspection device 100 can distinguish between pinholes 26, irregularities 27, and metal particles or foreign matter in a single image. Consequently, this defect inspection device 100 can perform defect inspection of layer members (11) in a shorter time compared to conventional defect inspection devices that require multiple images.

[0097] Although embodiments and modifications of the present invention have been described above, the configurations described in the above embodiments and modifications represent only a part of the application examples of the present invention and are not intended to limit the technical scope of the present invention.

Claims

1. A defect inspection method for inspecting defects in a layer member in the process of manufacturing a secondary battery using a flat layer member formed on an opaque substrate, using an image of the layer member taken at a frontal position, comprising: irradiating the layer member with a first color light at a first incidence angle; irradiating the layer member with a second color light different from the first color light at a second incidence angle greater than the first incidence angle; acquiring an image by imaging the layer member irradiated with the first color light and the second color light simultaneously; and detecting defects in the layer member based on the color of bright spots and shading contained in the image.

2. A defect inspection method according to claim 1, wherein the sum of the first angle of incidence and the second angle of incidence is 45 degrees or more.

3. A defect inspection method according to claim 2, wherein the first angle of incidence is 0 degrees or more and 45 degrees or less, and the second angle of incidence is 45 degrees or more and 90 degrees or less.

4. A defect inspection method according to claim 1, wherein the first color light and the second color light are selected from blue light, green light, or red light.

5. A defect inspection method according to claim 4, wherein the first color light or the second color light is blue light.

6. A defect inspection method according to claim 1, comprising imaging the layer member while the workpiece consisting of the substrate and the layer member is being transported.

7. A defect inspection method according to claim 6, wherein the layer member is imaged while the workpiece is moving during transport of the workpiece.

8. A defect inspection method according to claim 1, wherein the first color light and the second color light are irradiated onto the entire layer member, and the entire layer member is imaged in one pass using a single imaging device.

9. A defect inspection method according to claim 1, wherein the first color light and the second color light are parallel light.

10. A defect inspection method according to claim 1, comprising: determining pinholes based on bright spots having a color corresponding to the first color light; and determining irregularities based on shading.

11. A defect inspection method according to claim 1, comprising: irradiating a third color light, different from the first color light and the second color light, from a different direction from the first color light and the second color light, and acquiring the captured image by imaging the layer member irradiated simultaneously with the first color light, the second color light, and the third color light.

12. A defect inspection apparatus for inspecting defects in a layer member in the process of manufacturing a secondary battery using a flat layer member formed on an opaque substrate, using an image of the layer member taken at a frontal position, comprising: a first light source that irradiates the layer member with a first color light at a first incidence angle; a second light source that irradiates the layer member with a second color light different from the first color light at a second incidence angle greater than the first incidence angle; an imaging device positioned in front of the layer member and acquiring the image by imaging the layer member irradiated simultaneously with the first and second color lights; and an image analysis device that detects defects in the layer member based on the color of bright spots and shading included in the image.

Images