Electrode tab inspection apparatus for electrode assembly and electrode tab inspection method using same

Abstract

The present invention provides a cost-effective electrode tab inspection apparatus for quickly and accurately determining whether a stacked electrode tab is defective, and an electrode tab inspection method using same, the electrode tab inspection apparatus comprising: an imaging unit that images the electrode tab through transmission; an edge setting unit that sets edges for portions where color or brightness changes in an imaging result of the imaging unit; and a classification unit that classifies the edges set by the edge setting unit into edges related to stability and edges unrelated to stability.

Description

Electrode tab inspection device of electrode assembly and electrode tab inspection method using the same

[0001] The present invention relates to an electrode tab inspection device of an electrode assembly and an electrode tab inspection method using the same. Specifically, the present invention relates to an electrode tab inspection device for detecting defects occurring in electrode tabs that are laminated together when a plurality of electrodes are laminated, and an electrode tab inspection method using the same.

[0002] The electrode assembly may be formed as a jelly-roll type assembly having a structure in which a separator is interposed between long sheet-shaped positive and negative electrodes and then rolled up, a stack type assembly having a structure in which rectangular positive and negative electrodes are stacked with a separator interposed between them, a stack-folding type assembly in which unit cells are rolled up by a long separator film, or a lamination-stack type assembly in which battery cells are stacked with a separator interposed between them and attached to each other. An electrode assembly having a stacked structure is typically used for pouch-type battery cells.

[0003] Among various electrode assemblies, the laminated electrode assembly is formed by first manufacturing the positive electrode, negative electrode, and separator separately and then laminating them. The portion of the current collector formed by the thin metal foil used in the manufacture of the positive and negative electrodes, which forms the non-conductive portion, constitutes the electrode tab. When the negative electrode, separator, and positive electrode are laminated, the electrode tab is also laminated in the same manner.

[0004] Considering manufacturing efficiency, etc., the above lamination process is very fast, and as a result, folding, bending, and tearing may occur in the electrode tabs of the thin metal foil. In addition to folding, bending, and tearing, wrinkles and burrs also occur. Folding refers to the thin metals overlapping each other and folding, while bending refers to the shape itself being deformed, and tearing refers to the part of the thin metal foil being torn and separated from each other. During the lamination process, parts that have been stressed may be pushed, causing wrinkles, and wrinkles that have become stronger may also occur.

[0005] The electrode tabs are extremely thin and protrude outward as a non-laminated portion. This abnormal phenomenon can occur in various processes, including lamination, folding, and packaging processes, in addition to the lamination process of the cathode, separator, and anode. In other words, in addition to folding, bending, and tearing, wrinkles and dents can also occur in processes other than lamination.

[0006] Patent Document 1 relates to a device for determining deformation of laminated electrode tabs. The device measures the thickness of the electrode tab using short-circuit measuring devices positioned on one and the other sides of the electrode tab. If the measured thickness of the electrode tab is thicker than a predetermined thickness, it is determined that a bend or fold has occurred. Patent Document 1 determines whether a single electrode tab is defective by looking at it as a whole, and can only confirm macroscopic defects such as bending or folding of a single electrode tab. Since the defect is indirectly confirmed by measuring the thickness due to a short-circuit, there is also the problem of low accuracy.

[0007] Patent Document 2 discloses a device for detecting deformation of laminated electrode tabs. The device captures images from both sides of the laminated electrode tabs, and if the images differ, it determines that a fold has occurred. Patent Document 2 detects deformation based on laminated images of the side surfaces, making it impossible to identify defects that occur only internally and not on the side surfaces. Patent Document 2 also has the limitation that it uses two image sensors, which only support two sides and do not observe the front.

[0008] Patent Document 3 relates to a device for detecting defects in secondary battery electrode tabs, such as omissions and folding defects, and is a device that detects abnormalities using an image obtained by projecting X-rays at an angle onto stacked electrode tabs. The gap between the electrode tabs is checked in one image to detect defects. Patent Document 3 also acquires images for a first inclination angle and a second inclination angle rotated 90 degrees relative to the first inclination angle, and can detect defects by overlapping them. The projected image of Patent Document 3 has a stepped shape, and the gaps between them are not constant and gradually decrease or increase. In order to check the gaps or identify defects by overlapping, a separate means for judging these must be provided, or a person must directly judge them with the naked eye.

[0009] Patent Document 4 discloses a device and method for determining whether an electrode tab is folded. The device detects the load generated in the electrode tab by region during the process of bending and then elastically restoring the laminated electrode tab, thereby determining whether the electrode tab is folded. Since load testing requires the assumption that the material used is of consistent quality, errors may occur.

[0010] Various methods are being attempted to detect defects in laminated electrode tabs. Defects caused by folding or tearing of the tabs can cause low voltage or fire in battery cells, so they must be carefully selected and detected. With the increasing use of large-capacity battery packs for electric vehicles, ESS, and other applications, interest in methods capable of rapidly and comprehensively detecting laminated defects is also growing.

[0011] Among the various detection methods previously mentioned, the visual detection method using X-rays offers the highest precision in terms of measurement results. While the measurement results themselves are precise, the technology used to determine defects based on the visual data measured leaves many areas unsatisfactory.

[0012] The results measured by X-ray are black and white photographs, and the areas where the electrode tabs are laminated without any abnormalities have the same shade, but areas where folds, bends, tears, or wrinkles or dents occur show different shades from the surrounding areas.

[0013] The most basic method for assessing defects based on shade is human vision. While this method offers relatively high accuracy, it's performed manually, making it slow and impractical for practical application. Workers are constantly exposed to repetitive tasks, which can lead to stress and make it difficult to expect a consistent inspection rate.

[0014] It is possible to determine whether a product is defective by setting an absolute standard for shading or a relative standard with respect to the surroundings, but in this case, as can be seen in the examples / comparative examples below, there is a problem in that even non-defective cases are determined to be defective.

[0015] Judging shades is akin to pattern recognition, and artificial intelligence, such as deep learning, can be leveraged for this purpose. However, AI requires a separate learning process, making products produced during this learning process unreliable. Pattern learning typically requires approximately 10,000 samples, which may not be sufficient for the initial batch. Furthermore, for learning, users must manually determine whether each product is normal or defective and provide this information to deep learning. Continuous learning is also necessary to reduce detection errors. Furthermore, retraining is required if product specifications change. Electrode tab lamination is the most fundamental step in the entire battery cell manufacturing process, with a large number of cathodes and anodes being laminated at a very rapid pace. To smoothly apply deep learning to meet this rapid manufacturing speed, extremely powerful computing power is also required.

[0016] In line with these increased safety standards, a cost-effective electrode tab inspection device and an electrode tab inspection method using the same that can quickly and accurately determine whether laminated electrode tabs are defective have not yet been provided.

[0017] (Patent Document)

[0018] Republic of Korea Patent Publication No. 2020-0109040 (Patent Document 1)

[0019] U.S. Patent Publication No. 2023-0064943 (Patent Document 2)

[0020] Republic of Korea Patent Publication No. 10-2236815 ('Patent Document 3')

[0021] Republic of Korea Patent Publication No. 2023-0011760 (Patent Document 4)

[0022] The present invention is intended to solve the above-mentioned problem, and aims to provide an electrode tab inspection device that can quickly and accurately determine whether a laminated electrode tab is defective, and at a low cost, and an electrode tab inspection method using the same.

[0023] In order to achieve the above purpose, the present invention provides an electrode tab inspection device of an electrode assembly, comprising: a photographing unit that transmits and photographs the electrode tab; an edge setting unit that sets an edge for a portion of the photographing result of the photographing unit in which color or brightness changes; and a classification unit that classifies the edge set by the edge setting unit into one related to stability and one not related to stability. The electrode tab may be two or more single electrode tabs stacked. The photographing unit may transmit and photograph using X-rays.

[0024] The photographing unit according to the present invention corresponds to a conventional X-ray inspection device. When an electrode assembly including stacked electrode tabs is continuously moved via a conveyor belt, an X-ray device disposed on the upper or lower surface thereof emits X-rays, and equipment is disposed on the opposite surface of the X-ray device based on the electrode assembly to detect the X-rays that have passed through the electrode tabs. In order to minimize the impact on the electrode assembly and detect defects in the electrode tabs, it is preferable to use a low-power device of 50 kV or less for the X-rays.

[0025] The photographed results taken by the X-ray detection equipment are transmitted as digitalized photographed results to a computer placed on the side of the X-ray inspection device or to a server placed in a separate location for analysis.

[0026] The resulting images captured by X-ray detection equipment are grayscale, not black-and-white. Grayscale images or photographs can display varying levels of brightness depending on the settings. An 8-bit image can display 256 levels of black and white, while a 16-bit image can display 65,536 levels.

[0027] Fig. 1 is a diagram illustrating the form of a defect occurring in a laminated electrode tab. Fig. 1 is an enlarged view of a portion of an electrode assembly having an electrode tab. The protruding portion represents a laminated electrode tab, and the lower portion represents a portion having an active material. Fig. 1 illustrates the form of a defect by showing the defective portion as being laminated on the uppermost layer. In Fig. 1, the middle portion of the electrode tab represents the uppermost electrode tab, and the outermost portion of the electrode tab represents the electrode tab laminated on its lower surface. (a), (b), and (c) represent the back (flipped surface) of the uppermost electrode tab. The dotted line indicates a fold mark.

[0028] In Fig. 1, (a) to (c) illustrate folding of the electrode tab, and (d) to (f) illustrate cutting of the electrode tab. In (a), a portion of the left edge is folded, but the folded portion is inside the electrode tab, and the right edge shows a folded trace. In (b), the folded portion overlaps the electrode active material area. In (c), the upper portion of the electrode tab is completely folded horizontally.

[0029] (d) shows a part of the left corner cut off, and the right corner shows signs of being folded. (e) shows a form in which the right corner is largely cut off. In the case of (f), the upper part of the outermost electrode tab is completely folded. Due to the nature of X-rays, detection is possible even if they occur internally.

[0030] All of (a) to (f) in Figure 1 are defects that must be screened out as they affect the safety of the battery cell. However, the folded right corners of (a) and (d) may not be considered defects in some cases.

[0031] In the present invention, in the X-ray photographing results for the electrode tab, all folded portions or fold traces in (a) to (f) of FIG. 1 are set as edges. Setting an edge may be setting an edge for a portion where the color or brightness of a pixel changes in a digitized photographing result, and the portion where the color or brightness of the pixel changes may be a portion where the rate of change in the color or brightness of the pixel is greater than a reference value when measured. Setting a boundary by digitizing a digitized photographing result or digitizing a photographing result is one of the techniques widely used in recent photo editing programs.

[0032] By setting the edge, abnormal parts such as folds, bends, tears, wrinkles, and dents of the electrode tab are indicated. Setting the edge uses the differential value, which is the rate of change of the color or brightness of the pixel, for the digitized photographic result. Since the digitized photographic result is a collection of many numbers that cannot be expressed by a formula, a method of approximating the first derivative can be used to analytically simulate this rate of change or differential value. In addition, since the digitized photographic result is a two-dimensional result, a gradient including the rate of change in the x-axis and y-axis directions can be used.

[0033] Specific examples of methods for defining edges in digitized photographic results include the Sobel filter, the Marr-Hildreth edge filter, and the Canny edge filter, but any method capable of defining edges is not limited to these. Since the method of defining edges in digitized photographic results has been applied since the 1980s and is already widely known, a detailed explanation will be omitted.

[0034] The photographed results obtained by passing through the electrode tab according to the present invention are not complicated in color, brightness, and shape, and thus similar results can be obtained even using conventional edge setting methods. However, in terms of setting the criteria for whether there is an edge or selecting a specific filter, a method must be selected that can display wrinkles and burrs in addition to folds, bends, and tears that may appear in the electrode tab. A person skilled in the art can easily determine whether wrinkles and burrs are displayed in addition to the folds, bends, and tears by applying an edge selection method to a small number of digitized electrode tab photographed results that were previously photographed. Through this, an edge setting method or filter suitable for the process can be easily selected, and the selected method can be easily applied to subsequent detection.

[0035] The above classification unit may include a boundary setting unit that sets a predetermined closed polygon or closed curve for the photographing result, an edge classification unit that divides each edge that is not connected to each other, and a first classification unit that classifies the divided edges as being related to stability if they completely divide the predetermined closed polygon or closed curve into two regions, and classifies the divided edges as not related to stability if they do not.

[0036] The above classification unit may be replaced with a second classification unit that classifies the edge as being related to stability if each of the divided edges touches the corners of the predetermined closed polygon or closed curve more than twice, and classifies it as not being related to stability if it does not.

[0037] The above-described closed polygon or closed curve may be formed at the outer periphery of the electrode tab as viewed from above, or at a location spaced inward from the outer periphery. A specific example of the spaced location may be a location spaced inward from the outer periphery by 1 mm to 5 mm, preferably 2 mm to 3 mm.

[0038] If the above classification section classifies the electrode assembly as having an edge related to safety, a judgment section for determining the electrode assembly as defective may be added.

[0039] When the laminated electrode assembly is photographed using X-rays, the electrode tabs of the non-coated portion and the electrode active material layer show a large difference in shading. Through this, the outer perimeter of only the electrode tabs, which are non-coated portions, can be set as the above-described closed polygon or closed curve. When the electrode tabs are folded or bent, if the folded or bent portion does not extend beyond the boundary of the electrode tabs, i.e., if it does not come into contact with the electrode active material portion, the effect on safety is not significant in reality, so the corresponding portion can be excluded from the defect. In addition, the outer perimeter of the laminated electrode tabs can be cut separately. Taking these cases into consideration, the above-described closed polygon or closed curve can be set at a certain distance inward from the outer perimeter of only the electrode tabs, which are actually non-coated portions.

[0040] The present invention also provides an electrode tab inspection method of an electrode assembly, comprising a first step of photographing the electrode tab through the lens, a second step of setting an edge for a portion of the photographed result of the first step in which color or brightness changes, and a third step of classifying the edge of the second step into one related to stability and one unrelated to stability.

[0041] The above-described transmission and photography utilizes light that can penetrate the electrode tabs, and is not limited to anything that can penetrate and photograph the electrode tab material, but preferably, X-rays can be used. Meanwhile, the transmission and photography can be performed on the upper or lower surface of the stacked electrode tabs.

[0042] The above electrode tabs may be two or more single electrode tabs laminated.

[0043] The above first step may be to take a photograph by transmitting it using X-rays.

[0044] Setting the edge in the second step may be to set the edge for a portion of the digitized photographed result where the color or brightness of the pixel changes, and the portion where the color or brightness of the pixel changes may be a portion where the rate of change in the color or brightness of the pixel is greater than a reference value when measured. Setting a boundary in a digitized photographed result or by digitizing a photographed result is one of the techniques widely used in recent photo editing programs.

[0045] Setting the edge of the second step may be such that folds, bends, tears, wrinkles, and nicks of the electrode tab can be displayed.

[0046] Specifically, setting the edge uses the differential value, which is the rate of change in the color or brightness of the pixel, for the digitized photographic result. Since the digitized photographic result is a collection of many numbers that cannot be expressed in a formula, a method of approximating the first derivative can be used to analytically simulate this rate of change or differential value. In addition, since the digitized photographic result is a two-dimensional result, a gradient including the rate of change in the x-axis and y-axis directions can be used.

[0047] Specific examples of methods for defining edges in digitized photographic results include the Sobel filter, the Marr-Hildreth edge filter, and the Canny edge filter, but any method capable of defining edges is not limited to these. Since the method of defining edges in digitized photographic results has been applied since the 1980s and is already widely known, a detailed explanation will be omitted.

[0048] The photographed results obtained by passing through the electrode tab according to the present invention are not complicated in color, brightness, and shape, and thus similar results can be obtained even using conventional edge setting methods. However, in terms of setting the criteria for whether there is an edge or selecting a specific filter, a method must be selected that can display wrinkles and burrs in addition to folds, bends, and tears that may appear in the electrode tab. A person skilled in the art can easily determine whether wrinkles and burrs are displayed in addition to the folds, bends, and tears by applying an edge selection method to a small number of digitized electrode tab photographed results that were previously photographed. Through this, an edge setting method or filter suitable for the process can be easily selected, and the selected method can be easily applied to subsequent detection.

[0049] The third step may include a step 3-1 of setting a predetermined closed polygon or closed curve for the photographing result of the first step, a step 3-2 of dividing edges that are not connected to each other for the edges of the second step, and a step 3-3 of classifying the edges as being related to stability if each of the divided edges in the third step completely divides the predetermined closed polygon or closed curve into two regions, and classifying the edges as not related to stability if it does not.

[0050] The above step 3-3 can be replaced by classifying the edge divided in the above step 3-2 as being related to stability if it touches the corner of the predetermined closed polygon or closed curve more than twice, and classifying it as not related to stability if it does not.

[0051] The above steps 3-1 and 3-2 may be performed in a different order or simultaneously.

[0052] The above-described closed polygon or closed curve may be formed at the outer periphery of the electrode tab as viewed from above, or at a location spaced inward from the outer periphery. A specific example of the spaced location may be a location spaced inward from the outer periphery by 1 mm to 5 mm, preferably 2 mm to 3 mm.

[0053] In the above third step, if there is an edge related to safety, a fourth step may be added to determine that the electrode assembly is defective.

[0054] When the laminated electrode assembly is photographed using X-rays, the electrode tabs of the non-coated portion and the electrode active material layer show a large difference in shading. Through this, the outer perimeter of only the electrode tabs, which are non-coated portions, can be set as the above-described closed polygon or closed curve. When the electrode tabs are folded or bent, if the folded or bent portion does not extend beyond the boundary of the electrode tabs, i.e., if it does not come into contact with the electrode active material portion, the effect on safety is not significant in reality, so the corresponding portion can be excluded from the defect. In addition, the outer perimeter of the laminated electrode tabs can be cut separately. Taking these cases into consideration, the above-described closed polygon or closed curve can be set at a certain distance inward from the outer perimeter of only the electrode tabs, which are actually non-coated portions.

[0055] The present invention can also be provided by arbitrarily combining the means for solving the above problems.

[0056] The present invention provides an electrode tab inspection device for an electrode assembly, comprising: a photographing unit that takes pictures by penetrating the electrode tab; an edge setting unit that sets an edge for a part of the photographing result of the photographing unit where the color or brightness changes; and a classification unit that classifies the edges set by the edge setting unit into those related to stability and those not related to stability.

[0057] In addition, the present invention can also provide an electrode tab inspection method of an electrode assembly, which includes a first step of photographing the electrode tab through the first step, a second step of setting an edge for a part of the photographed result of the first step where the color or brightness changes, and a third step of classifying the edge of the second step into one related to stability and one not related to stability.

[0058] The electrode tab inspection device and the electrode tab inspection method using the same according to the present invention have the advantages of being able to quickly and accurately determine whether laminated electrode tabs are defective, and are also inexpensive. When applied, the electrode tab inspection device and the electrode tab inspection method using the same according to the present invention demonstrate 100% detection capability.

[0059] In addition, the electrode tab inspection device according to the present invention and the electrode tab inspection method using the same have simple inspection and detection methods, enabling real-time comprehensive inspection of produced electrode assemblies. The electrode tab inspection device according to the present invention and the electrode tab inspection method using the same can inspect 15 electrode assemblies per minute.

[0060] Figure 1 is a diagram illustrating the form of defects that occur in electrode tabs when laminating.

[0061] Figure 2 is an example of sequential application of the device and method according to the present invention to the photographing results of the electrode tab.

[0062] Figure 3 is a diagram illustrating the analysis mechanism of the device and method according to the present invention.

[0063] Figures 4 and 5 show examples of applying the device and method according to the present invention to defects in various electrode tabs.

[0064] In this application, the terms “includes,” “has,” or “comprises” are intended to specify the presence of a feature, number, step, component, part, or combination thereof described in the specification, but should be understood not to preclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0065] Additionally, the same drawing reference numerals are used for parts with similar functions and actions throughout the drawings. Throughout the specification, when a part is said to be connected to another part, this includes not only direct connections but also indirect connections with other elements intervening. Furthermore, inclusion of a component does not exclude other components unless specifically stated otherwise, but rather implies the inclusion of additional components.

[0066] Below, the present invention is explained using the photographing results of the electrode tab.

[0067] Fig. 2 is an example of sequential application of the device and method according to the present invention to the photographing results of electrode tabs. Fig. 2 shows the results of photographing stacked electrode tabs using X-rays and sequentially processing them using the device and method according to the present invention. In Fig. 2, A is an original photograph, B is a photograph with an edge set, and C is a photograph after classification. The electrode tab of Fig. 2 has a horizontally folded portion as in Fig. 1 (c), and the lower portion of the electrode tab in the photograph, that is, the portion close to the active material coating portion, has wrinkles in the electrode tab.

[0068] When an edge is set according to the present invention, a separate edge is displayed on top of the original photo as in B.

[0069] In B and C, various closed polygons or closed curves are set according to the present invention. If the folding or cutting of the electrode occurs close to the outermost part of the electrode tab, the affected part may not have a significant impact on the safety of the electrode. In addition, if the wrinkle of the electrode tab occurs immediately adjacent to the upper left or upper right corner of the electrode tab, if a closed polygon or closed curve is set as the shape of the electrode tab, such wrinkle can also be detected as a defect. In addition, a process of cutting a portion of the outer surface of the laminated electrode tab may be added through a post-process. In order to increase the detection rate for defects, it is preferable to set the closed polygon or closed curve at a certain distance inward rather than matching the actual outer surface of the electrode tab. In Fig. 2, such an inwardly spaced shape is indicated by a light-colored square. The preferable separation distance is adjustable, but 2 to 3 mm from the outer surface of the electrode tab is appropriate.

[0070] In Fig. 2, C divides each edge that is not connected to the edge set in B, and if each divided edge completely divides the predetermined closed polygon or closed curve into two regions, it is classified as being related to stability and is kept, and if not, it is classified as not being related to stability and is deleted.

[0071] FIG. 2 C can also be determined by classifying the edge as being related to stability and keeping it if the edge of each of the divided edges touches the corner of the predetermined closed polygon or closed curve more than twice, and classifying it as not related to stability and deleting it if not.

[0072] It is also mathematically easy to determine whether an edge, that is, a kind of straight line or curve, completely divides another closed polygon or closed curve into two regions, or touches the corners of another closed polygon or closed curve more than twice. All edges, closed polygons, or closed curves can be modeled on coordinates using formulas, etc., and whether they overlap can be easily determined by mathematically calculating them. Analysis tools for such images are simpler than the method of setting the edge mentioned above and have been widely used as vision tools for cameras since the 1980s. When applying the method according to the present invention, it has the advantage of not requiring a lot of computing resources such as deep learning, analysis is very fast, and separate training is not required, so it can be immediately applied to all products.

[0073] Referring to C of FIG. 2, it can be seen that wrinkles not related to defects have been removed, while folds remain. If an edge remains in C of FIG. 2, the corresponding electrode tab is defective, and if no edge remains, the corresponding electrode tab is not defective.

[0074] Figure 3 is a schematic diagram illustrating the analysis mechanism of the device and method according to the present invention. Figure 3 is a simple schematic diagram of the edge and closed polygon or closed curve of Figure 2. The squares in (a) and (b) represent closed polygons or closed curves, and the line segments with round points at both ends represent edges.

[0075] In Figure 3, (a) represents all edges that are defective, and (b) represents all edges that are not related to defects. It is very simple and efficient to capture results using X-rays. However, technology for determining defects using these results has not yet been developed. It requires a very long period of training and experience for a doctor to judge whether a patient has a disease based on X-ray results. The same applies to determining defects in electrode tabs using X-ray results. Methods using skilled users or artificial intelligence such as deep learning have been proposed. However, artificial intelligence requires separate learning, and for learning, the user must manually determine whether each product is normal or defective, which requires a high-spec computer. Continuous learning is necessary to increase the detection rate for defects, and even after going through this process, the detection rate for defects does not reach 100%.

[0076] The present invention has developed a very groundbreaking technology that achieves a 100% detection rate while very quickly determining defects in electrode tabs by setting edges using a conventional image processing method, separating each unconnected edge, and determining the physical contact relationship between these edges and a closed polygon or closed curve forming an electrode tab.

[0077] Figures 4 and 5 illustrate examples of applying the device and method according to the present invention to defects in various electrode tabs. In Figures 4 and 5, A is an original photograph, B is a photograph with edges set, and C is a photograph after classification. Since these are the same as Figure 2, a redundant description thereof will be omitted.

[0078] Fig. 4 specifically relates to the case of detecting a defect in a corner diagonal, and corresponds to (a) or (b) of Fig. 1. Fig. 5 corresponds to the case of a middle fold, and corresponds to (c) of Fig. 1 or the same case as Fig. 2. In Figs. 4 and 5, a to h indicated in parentheses correspond to respective electrode tabs.

[0079] (a) in Fig. 4 corresponds to a dent and was not considered a defect, and (b) corresponds to an electrode wrinkle and was not considered a defect. (c) and (d) show corner folding, wrinkles, and dents all occurring, but only the corner folding is clearly shown in the final C. (e) to (h) show corner folding and wrinkles occurring simultaneously, but only the corner folding is clearly shown in the final C.

[0080] Figures 5 (a) to (f) all have wrinkles, but it can be seen that the wrinkles appear as edges in B, but are completely removed in C, through the device and method according to the present invention. (c), (d), (e), and (f) all show cases where folding occurred, and (f) shows cases where upper folding and corner folding occurred simultaneously. It can be seen that the type and number of defects can be clearly identified in all cases.

[0081] The device and method according to the present invention were applied to the field for defects such as folding and cutting, and 156 cases of folding defects were judged as defective in 100%, and 132 cases of normal cases with only wrinkles, etc., which were not actual defects but were tested at the same time, were judged as normal in 100%. In addition, 153 cases of cutting defects were judged as defective in 100%, and 135 cases of normal cases with only wrinkles, etc., which were not actual defects but were tested at the same time, were judged as normal in 100%. As such, the device and method according to the present invention show an extremely high detection rate. On the other hand, when judging only with the image itself, the cases of judging as defective even though they are not defective are very high, at 37 / (37+156) for folding (19.4%) and 31 / (31+153) for cutting (16.8%).

[0082] As described above, specific parts of the present invention have been described in detail. To a person having ordinary skill in the art, such specific descriptions are merely preferred embodiments, and the scope of the present invention is not limited thereby. It is obvious to a person skilled in the art that various changes and modifications are possible within the scope and technical idea of ​​the present invention, and it is natural that such changes and modifications fall within the scope of the appended patent claims.

Claims

1. As an electrode tab inspection device of an electrode assembly, A photographing unit that takes pictures by penetrating the above electrode tab; An edge setting unit that sets an edge for a part of the photographed results of the above photographing unit where the color or brightness changes; A classification unit that classifies the edges set in the above edge setting unit into those related to stability and those not related to stability; An electrode tab inspection device including:

2. In paragraph 1, The above electrode tab inspection device is an electrode tab inspection device in which two or more single electrode tabs are laminated.

3. In paragraph 1, The above photographing unit is an electrode tab inspection device that uses X-rays to transmit and photograph.

4. In paragraph 1, An electrode tab inspection device that sets the edge for a part where the color or brightness of a pixel changes in a digitalized photographed result.

5. In paragraph 4, An electrode tab inspection device in which the color or brightness of the pixel changes and the rate of change of the color or brightness of the pixel is measured and the rate of change is greater than the reference value.

6. In paragraph 1, An electrode tab inspection device wherein the above edge setting is configured to display folds, bends, tears, wrinkles, and dents of the electrode tab.

7. In paragraph 1, The above classification section is, A boundary setting unit that sets a predetermined closed polygon or closed curve for the above shooting results; An edge classification unit that divides each edge that is not connected to each other into edges; A first classification unit that classifies the edge as being related to stability if each of the above divided edges completely divides the predetermined closed polygon or closed curve into two regions, and classifies it as not related to stability if it does not; An electrode tab inspection device including:

8. In paragraph 7, An electrode tab inspection device in which the above classification unit is replaced with a second classification unit that classifies the divided edges as being related to stability if they touch the corners of the predetermined closed polygon or closed curve more than twice, and classifies them as not being related to stability if they do not.

9. In paragraph 7, An electrode tab inspection device in which the above-described closed polygon or closed curve is formed on the outer periphery of the electrode tab as viewed from above, or at a position spaced inward from the outer periphery.

10. As a method for inspecting electrode tabs of an electrode assembly, Step 1: Taking a picture by penetrating the above electrode tab; A second step of setting an edge for a part of the photographed result of the first step where the color or brightness changes; and A third step that classifies the edges of the second step into those related to stability and those not related to stability; An electrode tab inspection method including:

11. In paragraph 10, The above electrode tab inspection method is an electrode tab inspection method in which two or more single electrode tabs are laminated.

12. In paragraph 10, The above first step is an electrode tab inspection method that uses X-rays to pass through and take pictures.

13. In paragraph 10, The electrode tab inspection method is to set the edge in the second step above by setting the edge for a part where the color or brightness of the pixel changes in the digitalized photographed result.

14. In paragraph 13, A method for inspecting electrode tabs in which the color or brightness of the pixel changes and the rate of change of the color or brightness of the pixel is greater than the reference value.

15. In paragraph 10, An electrode tab inspection method wherein the edge of the second step is set so that folding, bending, tearing, wrinkles, and nicks of the electrode tab can be displayed.

16. In paragraph 10, The third step above is, Step 3-1 of setting a predetermined closed polygon or closed curve for the shooting result of the above step 1; Step 3-2, which divides each edge that is not connected to the edge of the above step 2; Step 3-3, where if each edge divided in the above step 3-2 completely divides the predetermined closed polygon or closed curve into two regions, it is classified as being related to stability, and if not, it is classified as not being related to stability; An electrode tab inspection method including:

17. In paragraph 16, The above step 3-3 is an electrode tab inspection method in which, if each edge divided in the above step 3-2 touches the corner of the predetermined closed polygon or closed curve more than twice, it is classified as being related to stability, and if not, it is classified as not being related to stability.

18. In paragraph 16, An electrode tab inspection method in which the above steps 3-1 and 3-2 are performed in a changed order or simultaneously.

19. In paragraph 16, An electrode tab inspection method in which the above-described closed polygon or closed curve is formed at an outer periphery of the electrode tab as viewed from above, or at a location spaced inward from the outer periphery.

20. In paragraph 10, A fourth step of determining the electrode assembly as defective if there is an edge related to safety in the third step; A method for inspecting electrode tabs to which an electrode tab is added.

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