A method for detecting alignment of battery pole pieces

Abstract

The present application discloses a method for detecting the alignment of battery pole pieces, including obtaining an image of staggered arrangement of positive and negative pole pieces; extracting an image to be detected from the image of staggered arrangement of positive and negative pole pieces; dividing the image to be detected into multiple sub-image areas, and the multiple sub-image areas are sequentially distributed along a direction perpendicular to the arrangement of the positive and negative pole pieces; generating a comparison image for each sub-image area; judging whether the alignment of the battery pole pieces is qualified according to the comparison image. By detecting the alignment of the battery pole pieces, it is possible to accurately judge whether the alignment of the positive and negative pole pieces meets the specifications during the battery stacking or winding process, so as to avoid the stacked battery or wound battery performance not meeting the requirements when the alignment of the positive and negative pole pieces does not meet the specifications, thereby affecting the battery performance.

Description

Technical Field

[0001] The present application relates to the field of battery preparation, and in particular, to a method for detecting the alignment of battery pole pieces. Background Art

[0002] During the production of laminated batteries or wound batteries, multiple positive electrodes and multiple negative electrodes need to be arranged in an interlaced manner to form laminated batteries or wound batteries. However, during the lamination or winding process, if the alignment of multiple positive electrodes and multiple negative electrodes does not meet the requirements, the performance of the laminated batteries or wound batteries is affected. Traditionally, X-rays are usually used to detect whether the alignment of multiple positive electrodes and multiple negative electrodes meets the requirements, that is, X-rays are used to irradiate the staggered positive electrodes and negative electrodes, and obtain the staggered images of the positive and negative electrodes during the irradiation. The obtained staggered images of the positive and negative electrodes are binarized to form a binary image, and the image is extracted from the binary image for feature analysis. This detection method can only judge the image features and the detection is inaccurate. Summary of the invention

[0003] In view of the deficiencies in the prior art, the present application provides a method for detecting the alignment of battery pole pieces.

[0004] The battery pole piece alignment detection method of the present application includes:

[0005] Obtain an image of the staggered arrangement of positive and negative electrodes;

[0006] Extract the image to be detected from the staggered arrangement image of the positive and negative electrodes;

[0007] Dividing the image to be detected into a plurality of sub-image areas, wherein the plurality of sub-image areas are sequentially distributed along a direction perpendicular to the arrangement direction of the positive and negative electrode sheets;

[0008] A comparison image is generated for each sub-image region;

[0009] Determine whether the alignment of the battery electrodes is qualified based on the comparison image.

[0010] According to one embodiment of the present application, generating a comparison image for each sub-image region includes:

[0011] Obtaining the inflection point in each sub-image area;

[0012] A comparison image is generated according to the inflection points in each sub-image area.

[0013] According to an embodiment of the present application, obtaining the inflection point in each sub-image area includes:

[0014] Each sub-image area is converted into a binary image, and each binary image has a plurality of pixels arranged along a direction perpendicular to the arrangement direction of the positive and negative electrodes;

[0015] A group of mean data columns are obtained according to the grayscale values ​​of multiple pixels in each binary image, and each group of mean data columns has multiple mean data;

[0016] Convert each set of mean data columns into a two-dimensional image;

[0017] Get the inflection point from each 2D image.

[0018] According to one embodiment of the present application, obtaining a set of mean data columns according to the grayscale values ​​of multiple pixels in each binary image includes:

[0019] Set a window in each binary image;

[0020] Sliding window, the window starts from the first pixel among multiple pixels and traverses all pixels in sequence, and after each sliding action stops, multiple pixels are located in the window;

[0021] A mean value is calculated based on the grayscale values ​​of multiple pixels in the window after each sliding action stops;

[0022] According to the order in which the mean data are obtained, each mean data is combined to form a set of mean data columns.

[0023] According to one embodiment of the present application, converting each set of mean data columns into a two-dimensional image includes:

[0024] Set 2D coordinates;

[0025] Each mean data in each set of mean data columns is sequentially presented in the form of points in two-dimensional coordinates;

[0026] Connect multiple points in sequence to form a two-dimensional image in two-dimensional coordinates.

[0027] According to one embodiment of the present application, obtaining an inflection point from each two-dimensional image includes:

[0028] Obtain the point with the smallest ordinate value and the point with the largest ordinate value from the two-dimensional image;

[0029] Starting from the point with the smallest ordinate value to the point with the largest ordinate value, calculate the gradient of each point in turn;

[0030] If the gradient value calculated at one of the points is greater than or equal to a predetermined value, then the point is an inflection point.

[0031] According to an embodiment of the present application, starting from the point with the smallest ordinate value to the point with the largest ordinate value, sequentially calculating the gradient of each point includes: starting from the point with the smallest ordinate value to the point with the largest ordinate value, sequentially calculating the gradient of each point and three other points sequentially arranged with the point, and sequentially obtaining a first gradient value, a second gradient value, and a third gradient value;

[0032] If the gradient value calculated at one of the points is greater than or equal to a predetermined value, then the point is an inflection point, including: if the first gradient value is greater than or equal to a first predetermined value, the second gradient value is greater than or equal to a second predetermined value, and the third gradient value is greater than or equal to a third predetermined value, then the point is an inflection point, wherein the first predetermined value, the second predetermined value, and the third predetermined value are respectively between 0.8 cm and 1.2 cm, 1.8 cm and 2.2 cm, and 2.8 cm and 3.2 cm.

[0033] According to one embodiment of the present application, if among the first gradient value, the second gradient value and the third gradient value calculated for each point, the first gradient value is less than the first predetermined value, the second gradient value is less than the second predetermined value and / or the third gradient value is less than the third predetermined value, then the point with the smallest ordinate value and the point with the largest ordinate value are defined as inflection points.

[0034] According to one embodiment of the present application, judging whether the alignment of the battery pole pieces is qualified according to the comparison image includes:

[0035] Generate a comparison image based on the inflection point;

[0036] Displaying the comparison image in the sub-image area;

[0037] The alignment of the battery electrodes is judged to be qualified based on the height value of the comparison image.

[0038] According to an embodiment of the present application, judging whether the alignment of the battery electrode pieces is qualified according to the height value of the comparison image includes:

[0039] Get the height value of the comparison image;

[0040] If the height value of the comparison image is within the predetermined range, the battery electrode alignment is qualified, otherwise it is unqualified.

[0041] The battery pole piece alignment detection method of the present application, after obtaining the staggered arrangement image of the positive and negative pole pieces, extracts the image to be detected from the staggered arrangement image of the positive and negative pole pieces, and removes unnecessary images from it, thereby retaining necessary data, reducing redundant data, and avoiding unnecessary calculations. At the same time, the image to be detected is divided into multiple sub-image areas, and each sub-image area is calculated and detected separately, which further reduces the difficulty of calculation and improves the accuracy of detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0043] Figure 1 A schematic diagram of the staggered arrangement of positive and negative electrode sheets obtained in the embodiment;

[0044] Figure 2 A schematic diagram of an image to be detected in an embodiment;

[0045] Figure 3 A schematic diagram of a process for obtaining a mean data column in an embodiment;

[0046] Figure 4 is a schematic diagram of a two-dimensional image in an embodiment;

[0047] Figure 5 A schematic diagram showing a comparison image displayed in a sub-image area;

[0048] Figure 6 Schematic diagram of the stacked battery after stacking is completed. DETAILED DESCRIPTION

[0049] The following will disclose multiple embodiments of the present application with drawings. For the purpose of clear description, many practical details will be described together in the following description. However, it should be understood that these practical details should not be used to limit the present application. In other words, in some embodiments of the present application, these practical details are not necessary. In addition, in order to simplify the drawings, some conventional structures and components will be depicted in a simple schematic manner in the drawings.

[0050] In addition, in the present application, the descriptions of "first", "second", etc. are only used for descriptive purposes, and do not specifically refer to the order or sequence, nor are they used to limit the present application. They are only used to distinguish components or operations described with the same technical terms, and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present application.

[0051] The present application provides a battery pole piece alignment detection method, which is used in the production process of laminated batteries or wound batteries to detect whether the battery pole piece alignment meets the requirements. In this example, a laminated battery is taken as an example to further illustrate the battery pole piece alignment detection method of the present application.

[0052] Please refer to Figure 1 , Figure 1 The diagram is a schematic diagram of the staggered arrangement of the positive and negative electrodes. In the process of manufacturing the stacked battery, the positive electrode sheet-negative electrode sheet-positive electrode sheet-negative electrode sheet are stacked repeatedly, that is, the positive electrode sheet and the negative electrode sheet are stacked alternately. After the positive electrode sheet and the negative electrode sheet are stacked, the following is obtained: Figure 1 The staggered arrangement image of the positive and negative electrodes is shown. The staggered arrangement image 1 of the positive and negative electrodes consists of three regions, namely the first region 11, the second region 12 and the third region 13. The first region 11 is the background image, the second region 12 is the top region of the stacked sheets, and the third region 13 is the middle region of the stacked sheets. The staggered arrangement image 1 of the positive and negative electrodes can be obtained by taking a picture of the stacked sheets using an image capturing element such as a CCD camera. Figure 1 In the stacked battery, the direction along which the positive and negative electrodes are arranged is the direction in which the positive and negative electrodes are arranged alternately. In the stacked battery, the direction in which the positive and negative electrodes are arranged is the direction in which the electrodes are stacked. Figure 1 The horizontal direction in the diagram is the direction in which the positive and negative electrodes are arranged.

[0053] like Figure 2 As shown, Figure 2 The obtained positive and negative electrode staggered arrangement image 1 is processed, and the image to be detected 2 is extracted from the positive and negative electrode staggered arrangement image 1. Figure 1 The image 2 to be detected is extracted from the image 1 of the staggered arrangement of the positive and negative electrodes to form a new image, and other unnecessary areas are removed, and the image 2 to be detected is retained to reduce unnecessary calculations. In the process of removing unnecessary areas, part of the first area 11 away from the second area 12 in the image 1 of the staggered arrangement of the positive and negative electrodes is removed, and part of the third area 13 away from the second area 12 is removed, and part of the first area 11 and part of the third area 13 continuous with the second area 12 are retained.

[0054] After the extraction of the image 2 to be detected is completed, the image 2 to be detected is divided into a plurality of sub-image areas 21, and the plurality of sub-image areas 21 are sequentially distributed along a direction perpendicular to the arrangement direction of the positive and negative electrodes, that is, the image 2 to be detected is divided along the horizontal direction, so that the image 2 to be detected is divided into a plurality of sub-image areas 21. Among them, when dividing the sub-image areas 21, the sub-image areas 21 can be divided into (N-1)*2, where N is the number of positive electrodes in the stack. Subsequently, each of the plurality of sub-image areas 21 is processed and calculated, and each sub-image area 21 generates a comparison image, that is, the number of comparison images is the same as the number of sub-image areas 21, and whether the stack alignment is qualified is judged based on each comparison image.

[0055] When generating a comparison image for each sub-image region 21, the inflection point in each sub-image region 21 is first obtained, and then the comparison image is generated according to the inflection point in each sub-image region 21. Figure 2 As shown, since the image grayscale values ​​in the first area 11 , the second area 12 and the third area 13 are different, there is an inflection point between the first area 11 and the second area 12 , and there is an inflection point between the second area 12 and the third area 13 .

[0056] When obtaining the inflection point in each sub-image area 21, each sub-image area 21 is first subjected to binarization processing. When binarization processing is performed, the grayscale value of the pixel points on each sub-image area 21 is set to 0 or 255, that is, the entire sub-image area 21 presents an obvious black and white effect, so that in each sub-image area 21, the black area is blacker, the white area is whiter, and the area boundary is more obvious, so that each sub-image area 21 is converted into a binary image 3. In addition, in each binary image 3, a plurality of pixels 31 are arranged in a direction perpendicular to the stacking of the pole pieces, and then a group of mean data columns are obtained according to the grayscale values ​​of the plurality of pixels 31 in each binary image 3, each group of mean data columns has a plurality of mean data, and each group of mean data columns is converted into a two-dimensional image; and the inflection point is obtained from each two-dimensional image.

[0057] Among them, Figure 3As shown, it is a schematic diagram of the process of obtaining the mean data column. As shown in the figure, in this example, there are 50 pixels 31 in one of the binary images 3, and the 50 pixels 31 are arranged along the direction perpendicular to the arrangement of the positive and negative electrodes, that is, arranged along the longitudinal direction. A window 32 is set in the binary image 3, and the window 32 is slid from top to bottom along the direction perpendicular to the arrangement of the positive and negative electrodes. The window 32 starts to slide from the first pixel 31 at the top of the 50 pixels 31, and traverses all the pixels 31 in sequence. Specifically, when a window 32 is set in the binary image 3, the window 32 can frame a plurality of pixels 31 arranged in sequence. In order to facilitate the calculation of the mean and simplify the calculation, the number of pixels 31 that can be framed in the window can be an odd number and should not be too many, such as 3. The window 32 starts to slide from the first pixel 31 at the top. When sliding from the first pixel 31, there are 3 pixels 31 in the window 32, namely the first pixel 31, the second pixel 31 and the third pixel 31. The mean of the grayscale values ​​of the first pixel 31, the second pixel 31 and the third pixel 31 is calculated to obtain the first mean data, and then the window 32 slides down to the second pixel 31. At this time, there are 3 pixels 31 in the window 32, namely the second pixel 31, the third pixel 31 and the fourth pixel 31. The mean of the grayscale values ​​of the second pixel 31, the third pixel 31 and the fourth pixel 31 is calculated. , and the second mean data is obtained, and then the window 32 slides to the third pixel point 31. At this time, there are 3 pixel points 31 in the window, namely the third pixel point 31, the fourth pixel point 31 and the fifth pixel point 31. The mean of the grayscale values ​​of the third pixel point 31, the fourth pixel point 31 and the fifth pixel point 31 is calculated to obtain the third mean data. By analogy, the window slides over the fourth pixel point 31, the fifth pixel point 31 to the forty-eighth pixel point 31 in turn, and slides 47 times in total to obtain 47 mean data. The 47 mean data are combined in the order of acquisition to obtain a group of mean data columns. In this way, the mean data columns of each binary image 3 can be obtained respectively.

[0058] After obtaining the mean data column, each set of mean data column is converted into a two-dimensional image 4, such as Figure 4 As shown, it is a schematic diagram of a two-dimensional image 4. First, a two-dimensional coordinate is set, wherein the two-dimensional coordinate has an X-axis and a Y-axis, and each mean data in each group of mean data columns is sequentially presented in the two-dimensional coordinate in the form of a point, and multiple points are sequentially connected to form a two-dimensional image 4 in the two-dimensional coordinate. The point with the smallest ordinate value and the point with the largest ordinate value are obtained from the two-dimensional image 4; starting from the point with the smallest ordinate value to the point with the largest ordinate value, the gradient of each point is calculated in sequence, and if the gradient value calculated for one of the points is greater than or equal to the predetermined value, the point is an inflection point.

[0059] When performing gradient calculation, starting from the point with the smallest ordinate value to the point with the largest ordinate value, the gradient of each point and the other three points arranged in sequence with the point are calculated in sequence, and three gradient values ​​are obtained in sequence, and the three gradient values ​​are respectively the first gradient value, the second gradient value and the third gradient value. If the first gradient value is greater than or equal to the first predetermined value, the second gradient value is greater than or equal to the second predetermined value and the third gradient value is greater than or equal to the third predetermined value, then the point is an inflection point, wherein the first predetermined value, the second predetermined value and the third predetermined value are respectively between 0.8cm and 1.2cm, 1.8cm and 2.2cm and 2.8cm and 3.2cm. If among the first gradient value, the second gradient value and the third gradient value calculated for each point, the first gradient value is less than the first predetermined value, the second gradient value is less than the second predetermined value and / or the third gradient value is less than the third predetermined value, then the point with the smallest ordinate value and the point with the largest ordinate value are defined as inflection points. That is to say, when one of the following three conditions is not satisfied: the first gradient value calculated for each point is greater than or equal to the first predetermined value, the second gradient value is greater than or equal to the second predetermined value, and the third gradient value is greater than or equal to the third predetermined value, the inflection point cannot be obtained through the gradient calculation method. At this time, the point with the smallest ordinate value and the point with the largest ordinate value are defined as the inflection point.

[0060] Please continue reading Figure 4 , Figure 4The vertical coordinate value of point A is the smallest, and the vertical coordinate value of point B is the largest. Therefore, from point A all the way up to point B, the gradient of each point between A and B is calculated. When calculating the gradient specifically, the gradients of point A with C, D and E are calculated first, and the gradient values ​​|AC|, |AD| and |AE| are obtained in sequence. If |AC| is greater than or equal to the first predetermined value, |AD| is greater than or equal to the second predetermined value, and |AE| is greater than or equal to the third predetermined value, and the first gradient value, the second gradient value and the third gradient value are between 0.8cm and 1.2cm, 1.8cm and 2.2cm, and 2.8cm and 3.2cm, then point A is an inflection point. Otherwise, if any one, two or three of |AC| is greater than or equal to the first predetermined value, |AD| is greater than or equal to the second predetermined value, and |AE| is greater than or equal to the third predetermined value are not satisfied, point A is not an inflection point. Then the gradients of point C with D, E and F are calculated respectively, and the gradient values ​​|CD|, |AE| are obtained in sequence. |CE| and |CF|, if |CD| is greater than or equal to the first predetermined value, |CE| is greater than or equal to the second predetermined value, and |CF| is greater than or equal to the third predetermined value, wherein the first gradient value, the second gradient value, and the third gradient value are between 0.8cm and 1.2cm, 1.8cm and 2.2cm, and 2.8cm and 3.2cm, then point C is the inflection point, otherwise, if any one, two, or three of |CD| is greater than or equal to the first predetermined value, |CE| is greater than or equal to the second predetermined value, and |CF| is greater than or equal to the third predetermined value are not satisfied, point C is not the inflection point, and so on and so forth, two inflection points are found in each two-dimensional image 4, one of which is located between the first area 11 and the second area 12, and the other is located between the second area 12 and the third area 13. When the inflection point cannot be obtained by calculating the gradient, the highest point B and the lowest point A are the inflection points.

[0061] Please refer to Figure 5As shown, it is a schematic diagram of the comparison image displayed in the sub-image area. After completing the search for the inflection point in each two-dimensional image 4, a comparison image 5 is generated according to the inflection point, and the comparison image 5 is displayed in the sub-image area 21. The stacking alignment is judged to be qualified according to the height value of the comparison image 5. Among them, after obtaining the inflection point between the first area 11 and the second area 12 and the two inflection points between the second area 12 and the third area 13, the corresponding positions of the two inflection points in the corresponding two-dimensional image 4 are determined, and then according to the corresponding positions of the two inflection points in the corresponding two-dimensional image 4, the mean data of the grayscale values ​​corresponding to the two inflection points are obtained, and then the 6 pixel points 31 when calculating the mean data are obtained according to the two mean data, so as to form a comparison image 5 according to the 6 pixel points 31, and the comparison image 5 is displayed in the corresponding sub-image area 21, and then the height value of the comparison image 5 along the direction perpendicular to the stacking direction of the pole pieces is calculated. If the height value of the comparison image 5 is within the predetermined range, the stacking alignment is qualified, otherwise it is unqualified. Among them, the predetermined range can be set according to the requirements of different types of stacked batteries. Under normal circumstances, please refer to Figure 6 As shown, it is a schematic diagram of a laminated battery after lamination is completed. When lamination is completed to form a laminated battery 6, the two corners 63 and 64 located on the same side of the positive ear 61 or the same side of the negative ear 62 are grouped together. After detecting and obtaining the corresponding images of the corners 63 and 64, when the sum of the distance difference between the positive electrode sheet and the negative electrode sheet in the two corners 63 and 64 images is 2 cm, the height value of the comparison image 5 is 0.15 cm to 1.85 cm. At this time, the laminated battery obtained is a good product. If the performance requirements of the laminated battery are higher, the height value of the comparison image 5 is smaller.

[0062] The stacking alignment detection method of the present application, after obtaining the staggered arrangement image of the positive and negative electrodes, extracts the image to be detected from the staggered arrangement image of the positive and negative electrodes, and removes unnecessary images from the staggered arrangement image of the positive and negative electrodes, thereby retaining necessary data, reducing redundant data, and avoiding unnecessary calculations. When processing the sub-image area, the sub-image area is first binarized to obtain a binary image. The grayscale changes in the binary image are obvious, the boundaries are clear, and it is more conducive to subsequent image processing and calculation. At the same time, the image to be detected is divided into multiple sub-image areas, and each sub-image area is calculated and detected separately, which further reduces the difficulty of calculation and improves the accuracy of detection.

[0063] The above is only an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. A method for detecting the alignment of battery pole pieces, characterized in that: include: Obtain an image of the staggered arrangement of positive and negative electrodes; Extracting the image to be detected from the staggered arrangement image of the positive and negative electrode sheets; Dividing the image to be detected into a plurality of sub-image areas, wherein the plurality of sub-image areas are sequentially distributed along a direction perpendicular to the arrangement direction of the positive and negative electrode sheets; A comparison image is generated for each sub-image region; Judging whether the alignment of the battery pole pieces is qualified according to the comparison image; Generating a comparison image for each sub-image area includes: Obtaining the inflection point in each sub-image area; Generate a comparison image according to the inflection points in each sub-image area; The obtaining of the inflection point in each sub-image area comprises: Each sub-image area is converted into a binary image, and each binary image has a plurality of pixels arranged along a direction perpendicular to the arrangement direction of the positive and negative electrodes; A group of mean data columns are obtained according to the grayscale values ​​of multiple pixels in each binary image, and each group of mean data columns has multiple mean data; Convert each set of mean data columns into a two-dimensional image; Obtain inflection points from each 2D image; The step of obtaining a set of mean value data columns according to the grayscale values ​​of a plurality of pixels in each binary image comprises: Set a window in each binary image; Sliding the window, wherein the window starts from a first pixel point among the multiple pixel points and sequentially traverses all the pixel points, and after each sliding action stops, the multiple pixel points are located within the window; A mean value is calculated based on the grayscale values ​​of multiple pixels in the window after each sliding action stops; According to the order in which the mean data are obtained, each mean data is combined to form a set of mean data columns.

2. The battery pole piece alignment detection method according to claim 1, characterized in that: The step of converting each set of mean value data columns into a two-dimensional image comprises: Set 2D coordinates; Each mean data in each set of mean data columns is sequentially presented in the form of points in two-dimensional coordinates; A plurality of points are connected in sequence to form a two-dimensional image in the two-dimensional coordinates.

3. The battery pole piece alignment detection method according to claim 2, characterized in that: The step of obtaining an inflection point from each two-dimensional image comprises: Obtaining a point with a minimum ordinate value and a point with a maximum ordinate value from the two-dimensional image; Starting from the point with the smallest ordinate value to the point with the largest ordinate value, the gradient of each point is calculated in sequence; If the gradient value calculated at one of the points is greater than or equal to a predetermined value, then the point is an inflection point.

4. The battery pole piece alignment detection method according to claim 3, characterized in that: Starting from the point with the smallest ordinate value to the point with the largest ordinate value, sequentially calculating the gradient of each point includes: starting from the point with the smallest ordinate value to the point with the largest ordinate value, sequentially calculating the gradient of each point and three other points arranged sequentially with the point, and sequentially obtaining a first gradient value, a second gradient value, and a third gradient value; If the gradient value calculated at one of the points is greater than or equal to a predetermined value, then the point is an inflection point, including: if the first gradient value is greater than or equal to a first predetermined value, the second gradient value is greater than or equal to a second predetermined value, and the third gradient value is greater than or equal to a third predetermined value, then the point is an inflection point, wherein the first predetermined value, the second predetermined value, and the third predetermined value are respectively between 0.8 cm~1.2 cm, 1.8 cm~2.2 cm, and 2.8 cm~3.2 cm.

5. The battery pole piece alignment detection method according to claim 4, characterized in that: If among the first gradient value, the second gradient value and the third gradient value calculated for each point, the first gradient value is less than the first predetermined value, the second gradient value is less than the second predetermined value and / or the third gradient value is less than the third predetermined value, then the point with the smallest ordinate value and the point with the largest ordinate value are defined as inflection points.

6. The battery pole piece alignment detection method according to any one of claims 3 to 5, characterized in that: Judging whether the alignment of the battery pole pieces is qualified according to the comparison image includes: generating the comparison image according to the inflection point; Displaying the comparison image in the sub-image area; Whether the alignment of the battery pole pieces is qualified is judged according to the height value of the comparison image.

7. The battery pole piece alignment detection method according to claim 6, characterized in that: Judging whether the alignment of the battery pole pieces is qualified according to the height value of the comparison image includes: Obtaining a height value of the comparison image; If the height value of the comparison image is within a predetermined range, the alignment of the battery electrode sheets is qualified, otherwise it is unqualified.

Images