Offset detection method and offset detection device

Abstract

The present application provides an offset detection method and device, relating to the field of battery manufacturing. The method comprises: an image acquisition step, in which a camera captures multiple first images and multiple second images during the winding process of an electrode assembly, wherein the first image includes the first electrode sheet and the second image includes the second electrode sheet; an image matching step, in which a first image and a second image are matched, wherein the first image and the second image contain the same or corresponding identification objects, which are portions periodically formed in each winding layer of the electrode assembly; and an offset determination step, in which, within a set of matched first and second images, the electrode assembly is determined to be offset based on the boundary of the first electrode sheet in the first image and / or the boundary of the second electrode sheet in the second image. This allows the positional offset of the first and second electrode sheets located at the same position in the same winding layer to be determined more accurately.

Description

Technical Field

[0001] The present application relates to the field of battery manufacturing, and in particular to an offset detection method and an offset detection device for detecting positional offset of an electrode assembly when the electrode assembly is wound and manufactured. Background Art

[0002] The electrode assembly, the component where the electrochemical reaction occurs in a battery cell, is typically formed by winding or stacking a first electrode sheet, a second electrode sheet, and a separator. During the winding process, these electrodes and separators are prone to deflection, causing them to deviate from their normal positions. The quality of electrode assembly winding directly impacts battery cell performance. Therefore, accurately detecting electrode assembly deflection is crucial for battery manufacturing. Summary of the Invention

[0003] In view of the above problems, the present invention provides a deviation detection method and a deviation detection device, which can accurately detect the position deviation of the wound electrode assembly.

[0004] In a first aspect, an offset detection method is provided for detecting the position offset of an electrode assembly during winding, the electrode assembly comprising a first electrode sheet and a second electrode sheet, the offset detection method comprising: an image acquisition step, during the winding process of the electrode assembly, acquiring a plurality of first images and a plurality of second images by a shooting unit, the first image comprising the first electrode sheet, and the second image comprising the second electrode sheet; an image matching step, matching a first image and a second image, the matched first image and the matched second image comprising the same or corresponding identification objects, the identification objects being parts periodically formed in each winding layer of the electrode assembly; an offset determination step, in a set of matched first images and second images, determining whether the electrode assembly is offset based on the boundary of the first electrode sheet in the first image and / or the boundary of the second electrode sheet in the second image.

[0005] In the technical solution of the embodiment of the present application, due to the influence of the winding speed of the electrode assembly winding device and the position of the shooting unit, the first electrode piece on the first image and the second electrode piece on the second image obtained at the same time may not have a corresponding relationship with each other. That is, the second electrode piece on the second image obtained at the same time may enter the electrode assembly winding device earlier than the first electrode piece on the first image. The technical solution of the embodiment of the present application ensures that the first electrode piece and the second electrode piece in a set of matching first and second images correspond to each other by matching the first image and the second image, that is, the first electrode piece and the second electrode piece in a set of matching first and second images are in the same winding layer in the electrode assembly after winding. Therefore, the position offset of the electrode assembly during winding can be determined more accurately.

[0006] In some embodiments, in the offset determination step, a comparison area is set according to the identification object, and whether the electrode assembly has offset is determined based on the boundary of the first electrode piece in the comparison area of ​​the first image and / or the boundary of the second electrode piece in the comparison area of ​​the second image. The image matching step can ensure that the first image and the second image to be determined are two images of the same winding layer. The comparison area determined by the identification object can further ensure that the area for offset determination is the same area of ​​the first electrode piece and the second electrode piece that overlap each other in the same winding layer. In this way, the position offset of the electrode assembly during winding can be determined more accurately.

[0007] In some embodiments, the first image is of the electrode assembly before winding on the winding needle, and the second image is of the electrode assembly after winding on the winding needle. During winding on the winding needle, the electrode sheet is prone to shifting. The first and second images can be used to respectively capture the electrode sheet's pre- and post-winding states, thereby determining whether the electrode assembly has shifted during the winding process.

[0008] In some embodiments, during the image acquisition step, the first and second images are acquired while the winding needle rotates through a preset angle. By setting the preset angle, each of the output first and second images can be guaranteed to contain only one identification object, thereby ensuring that the identification object can be used to determine the comparison area in the first and second images. Furthermore, since the images are acquired while rotating, offset determination can be performed in real time.

[0009] In some embodiments, the capturing unit includes a first camera and a second camera. The first camera captures the first image, and the second camera captures the second image. The first camera and the second camera capture images of opposite sides of the electrode assembly, respectively. Since the electrode assembly 100 is susceptible to displacement during winding on the winding needle, by comparing the first image T1 and the second image T2 of opposite sides of the electrode assembly 100, it can be determined whether the first electrode piece 1 and the second electrode piece 2 have shifted during winding on the winding needle.

[0010] In some embodiments, in the image matching step, the (n+1)th second image acquired in the image acquisition step is matched with the nth first image. Affected by the winding speed of the electrode assembly winding device and the position of the shooting unit, the electrode assembly in the second image acquired at the same time is earlier than the first electrode assembly in the first image, and there is no identification object in the first image of the second image T2. By matching the (n+1)th second image with the nth first image, it is possible to ensure that the electrode assemblies in a set of matched second images and the first image correspond to each other, that is, the first electrode sheet and the second electrode sheet in a set of matched first and second images are in the same winding layer in the wound electrode assembly, thereby more accurately determining the position offset of the electrode assembly during winding.

[0011] In some embodiments, the identification object is the tab of the first electrode piece and / or the tab of the second electrode piece in the same winding layer. Since the tab of the first electrode piece and / or the tab of the second electrode piece are periodically formed in each winding layer of the electrode assembly, there is no need to provide additional identification objects on the electrode assembly. The comparison area in the first image and the second image can be determined solely by the tab of the first electrode piece and / or the tab of the second electrode piece.

[0012] In some embodiments, in the offset determination step, in a set of matched first and second images, a first distance is obtained in the first image, and a second distance is obtained in the second image, wherein the first distance is the distance from a first reference point to the boundary of the first electrode piece, and the second distance is the distance from a second reference point to the boundary of the second electrode piece. When the difference between the first and second distances minus a preset distance between the boundary of the first electrode piece and the boundary of the second electrode piece is greater than a first threshold, it is determined that the electrode assembly has offset. Thus, by comparing the first and second distances, the relative positional relationship between the first and second electrode pieces can be determined, thereby determining whether the electrode assembly has offset during winding.

[0013] In some embodiments, in the offset determination step, in a set of matching first and second images, a first distance is obtained in the first image, and a second distance is obtained in the second image, wherein the first distance is the distance from the first reference point to the boundary of the first pole piece, and the second distance is the distance from the second reference point to the boundary of the second pole piece. By comparing the first distance with a preset value of the first distance, it is determined whether the first pole piece has offset, and by comparing the second distance with the preset value of the second distance, it is determined whether the second pole piece has offset. Thus, by comparing the first and second distances with the preset values, it is possible to determine whether the first pole piece and the second pole piece have offset, respectively. Compared with determining the relationship between the first distance and the second distance, it is possible to more accurately determine which pole piece has offset.

[0014] In a second aspect, an offset detection device is provided for detecting the position offset of an electrode assembly during winding, wherein the electrode assembly includes a first electrode sheet and a second electrode sheet, and the offset detection device includes: an image acquisition unit for acquiring a plurality of first images and a plurality of second images during the winding process of the electrode assembly, wherein the first image includes the first electrode sheet and the second image includes the second electrode sheet; an image matching unit for matching a first image with a second image, wherein the matched first image and the matched second image contain the same or corresponding identification objects, and the identification objects are parts periodically formed in each winding layer of the electrode assembly; an offset determination unit for determining whether the electrode assembly is offset based on a boundary of the first electrode sheet in the first image and / or a boundary of the second electrode sheet in the second image for a set of matched first images and second images. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] 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:

[0016] Figure 1 Schematic diagram of an electrode assembly manufacturing device including an embodiment of the present application.

[0017] Figure 2 Schematic diagram of a wound electrode assembly according to an embodiment of the present application.

[0018] Figure 3 4 is a cross-sectional view of an XY cross-section of a wound electrode assembly according to an embodiment of the present application.

[0019] Figure 4 Schematic diagram of an expanded electrode assembly according to an embodiment of the present application.

[0020] Figure 5 4 is a flow chart of an offset detection method according to an embodiment of the present application.

[0021] Figure 6 Schematic diagram of a set of matching first and second images according to one embodiment of the present application.

[0022] Description of reference numerals:

[0023] 100 electrode assembly, 1 first electrode piece, 11 first electrode tab, 2 second electrode piece, 22 second electrode tab, 3 diaphragm, 4 shooting unit, 41 first camera, 42 second camera, 5 winding needle, 6 identification object, α preset angle, T1 first image, T2 second image, S comparison area, A1 first reference point, A2 second reference point, d1 first distance, d2 second distance, 200 offset detection method, 210 image acquisition step, 220 image matching step, 230 offset determination step. Specific embodiments

[0024] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0025] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first" and "second" in the specification and claims of this application or the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order or a primary-secondary relationship.

[0026] References to "embodiments" in this application mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described in this application may be combined with other embodiments.

[0027] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "attached" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0028] The term "and / or" in this application simply describes an association between related objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects are in an "or" relationship.

[0029] The term "multiple" in this application refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0030] Figure 1 Schematic diagram of an electrode assembly manufacturing device including an embodiment of the present application. Figure 2 FIG. 1 shows an electrode assembly 100 formed by winding. Figure 1 The electrode assembly manufacturing equipment includes a conveying device and a winding device (winding needle 5). The conveying device conveys the strip-shaped first electrode sheet 1, the second electrode sheet 2 and the diaphragm 3 to the winding device, and the first electrode sheet 1, the diaphragm 3, the second electrode sheet 2 and the diaphragm 3 are stacked and wound in the winding device in sequence to form an electrode assembly 100 (refer to Figure 2 ). Figure 1 The winding needle 5 is only for illustration. According to the type of battery cell and the shape of the battery shell, the electrode assembly can be wound into an electrode assembly with a cylindrical cross section, or an elliptical electrode assembly (such as Figure 2 、 Figure 3 shown).

[0031] Each time the winding needle 5 rotates one circle (360°), the electrode assembly 100 increases by one layer. Figure 2 As shown, as the winding needle 5 rotates, the thickness of the electrode assembly 100 in the X-axis direction gradually increases. In addition, the width of the strip-shaped first electrode sheet 1, the second electrode sheet 2 and the diaphragm 3 determines the height of the electrode assembly 100 in the Z-axis direction. Figure 3 yes Figure 2 The cross-sectional view of the electrode assembly 100 shown in FIG. Figure 3 As shown, for each winding layer, from outside to inside along the X direction, there are the diaphragm 3, the second pole piece 2, the diaphragm 3 and the first pole piece 1. Therefore, for each winding layer, the diaphragm 3 separates the second pole piece 2 and the first pole piece 1.

[0032] A more important parameter in the electrode assembly winding process is the alignment of the electrode assembly 100 in the Z-axis direction after winding. Specifically, the alignment of the electrode assembly 100 in the Z-axis direction after winding is the relative position of the second electrode sheet 2 and the first electrode sheet 1 in the Z-axis direction. Figure 4 : is an expanded view of the stacked and wound electrode assembly 100 along the Y direction. Figure 4 As shown, in the Z-axis direction (i.e., the width direction of the unfolded electrode assembly 100), from the outside to the inside, they should be: diaphragm 3, second pole piece 2, another diaphragm 3, and first pole piece 1. That is, in the Z-axis direction, the diaphragm 3 is located at the outermost side, while the first pole piece 1 is located at the innermost side, and the second pole piece 2 exceeds the first pole piece 1 by a preset distance. Since the second pole piece 2 and the first pole piece 1 are prone to deflection during the winding process of the electrode assembly 100, the relative position of the second pole piece 2 and the first pole piece 1 is offset, thereby affecting the quality and performance of the manufactured battery cell. Therefore, in order to monitor the relative position offset of the second pole piece 2 and the first pole piece 1, the electrode assembly manufacturing equipment also includes a shooting unit 4.

[0033] Ideally, the shooting unit shoots the wound electrode assembly 100 and identifies the second electrode piece 2 and the first electrode piece 1 in the obtained image to determine the relative positional relationship between the second electrode piece 2 and the first electrode piece 1. However, as mentioned above, for each winding layer of the electrode assembly, in order to shoot the first electrode piece 1, it is necessary to penetrate the diaphragm 3, the second electrode piece 2, and another diaphragm 3 located between the second electrode piece 2 and the first electrode piece 1. Due to the limitations of existing shooting units, for example, the penetration ability of infrared shooting units is very limited, it is difficult to simultaneously identify the second electrode piece 2 and the first electrode piece 1 and determine their relative positional relationship in an image of the wound electrode assembly 100. Therefore, it is necessary to use images of the first electrode piece 1 and the second electrode piece 2 (corresponding to the first image T1 and the second image T2, respectively) to determine the electrode piece position offset.

[0034] In order to photograph the first electrode 1, it is necessary to use the image before winding (at this time, the second electrode 2 and the two layers of diaphragm 3 have not yet been stacked on the first electrode 1). In addition, as mentioned above, position offset is likely to occur during the winding process. Therefore, the photo of the second electrode 2 needs to use the image after winding. However, the first electrode 1 in the first image T1 obtained at the same time and the second electrode 2 in the second image T2 do not correspond to each other. That is, the second electrode 2 on the second image T2 obtained at the same time enters the electrode assembly winding device (winding needle 5) earlier than the first electrode 1 in the first image T1. Therefore, the problem of how to use the shooting unit 4 to accurately determine the relative position offset between the second electrode 2 and the first electrode 1 arises.

[0035] Based on the above considerations, the inventors have proposed a deviation detection method after in-depth research. Figure 5 FIG. 1 is a flow chart of an offset detection method according to an embodiment of the present application. Figure 5 As shown, the offset detection method 200 includes: an image acquisition step 210, during the winding process of the electrode assembly 100, a plurality of first images T1 and a plurality of second images T2 are acquired by the shooting unit 4, the first image T1 includes the first electrode piece 1, and the second image T2 includes the second electrode piece 2; an image matching step 220, matching a first image T1 and a second image T2, a first image T1 and a second image T2 contain the same or corresponding identification objects 6, and the identification objects 6 are parts periodically formed in each winding layer of the electrode assembly 100; an offset determination step 230, in a set of matched first images T1 and second images T2, judging whether the electrode assembly 100 is offset according to the boundary of the first electrode piece 1 in the first image T1 and / or the boundary of the second electrode piece 2 in the second image T2.

[0036] In order to compare the relative positions of the second electrode sheet 2 and the first electrode sheet 1 located at the same position in the same winding layer in the wound electrode assembly 100 using the first image T1 and the second image T2, a method according to an embodiment of the present application defines an identification object, which is a portion periodically formed in each winding layer of the electrode assembly 100. Therefore, the first image T1 and the second image T2 taken for each layer both contain the identification object.

[0037] By identifying the identification object, a pair of images T1 and T2 capturing the same or corresponding identification object are matched. The offset determination step 230 is performed using the matched pair of images T1 and T2. This ensures that the offset determination step 230 determines the first electrode piece 1 and the second electrode piece 2 located at the same position in the same winding layer of the wound electrode assembly 100, thereby accurately determining the positional offset of the electrode assembly 100.

[0038] According to some embodiments of the present application, Figure 6 As shown, the identification object 6 is the tab 11 of the first electrode sheet 1 and / or the tab 22 of the second electrode sheet 2 in the same winding layer. Since the tab 11 of the first electrode sheet 1 and / or the tab 22 of the second electrode sheet 2 are periodically formed in each winding layer of the electrode assembly, there is no need to set additional identification objects on the electrode assembly 100. The first image T1 and the second image T2 can be matched solely by the tab 11 of the first electrode sheet and / or the tab 22 of the second electrode sheet. In addition, the identification object 6 is not limited to the tab 11 of the first electrode sheet 1 and the tab 22 of the second electrode sheet 2; as long as it appears in each of the first image T1 and the second image T2, it can be used.

[0039] According to some embodiments of the present application, in the offset determination step, a comparison area S is set according to the identification object, and whether the electrode assembly 100 is offset is determined based on the boundary of the first electrode piece 1 in the comparison area S of the first image T1 and / or the boundary of the second electrode piece 2 in the comparison area S of the second image T2.

[0040] like Figure 6 As shown, in the Y direction, the distance between the comparison area S on the first image T1 and the identification object 6 is equal to the distance between the comparison area S on the second image T2 and the same or corresponding identification object 6. Therefore, as long as it is ensured that the identification object 6 on the first image T1 and the identification object 6 on the second image T2 correspond to each other, it can be ensured that the comparison area S on the first image T1 and the comparison area S on the second image T2 are in the same area of ​​the first electrode 1 and the second electrode 2 that are superimposed on each other in the same winding layer. In this way, the position offset of the electrode assembly during winding can be determined more accurately. In addition, the comparison area S is an area with a specified length in the Y direction. The specified length is less than the unfolded length of a winding layer. By determining the relative position offset of the first electrode 1 and the second electrode 2 over the specified length, instead of determining the position offset over the entire unfolded length, the offset determination rate can be improved.

[0041] According to some embodiments of the present application, the first image T1 is an image of the electrode assembly 100 before being wound on the winding needle 5 , and the second image T2 is an image of the electrode assembly 100 after being wound on the winding needle 5 .

[0042] like Figure 6 As shown, in the first image T1, which captures the electrode assembly 100 before winding, the first electrode sheet 1 is located outermost along the X-axis. Below the first electrode sheet 1 are, in order, the separator 3, the second electrode sheet 2, and another separator 3. Due to the penetrating power of the imaging unit 4, the first electrode sheet 1 and the separator 3 can be identified in the first image T1. In the second image T2, which captures the electrode assembly 100 after winding, the separator 3 is located outermost along the X-axis. Below the separator 3 are, in order, the second electrode sheet 2, another separator 3, and the first electrode sheet 1. Due to the penetrating power of the imaging unit 4, the separator 3 and the second electrode sheet 2 can be identified in the second image T2. Furthermore, the first electrode sheet 1 in the first image T1 shows the electrode assembly 100 before winding, while the second electrode sheet 2 in the second image T2 shows the electrode assembly 100 after winding.

[0043] Since the electrode assembly 100 is prone to shifting during winding, by comparing the second image T2 of the electrode assembly 100 after winding with the first image T1 of the electrode assembly 100 before winding, it is possible to determine whether the first electrode sheet 1 and the second electrode sheet 2 have shifted during the winding process.

[0044] According to some embodiments of the present application, in the image acquisition step 210 , when the winding needle 5 rotates by a preset angle α, a first image T1 and a second image T2 are acquired.

[0045] Reference Figure 1 Each time the winding needle 5 rotates through a preset angle α (e.g., α = 360°), it outputs a first image T1 containing the first pole piece 1 and a second image T2 containing the second pole piece 2. The angle α is not limited to 360°; it is sufficient to ensure that each output first image T1 and second image T2 contains only one identical or corresponding identification object 6. Furthermore, because images are acquired during rotation, offset determination can be performed in real time.

[0046] According to some embodiments of the present application, referring to Figure 1 The photographing unit 4 includes a first camera 41 and a second camera 42 . The first camera 41 photographs a first image T1 , and the second camera 42 photographs a second image T2 . The first camera 41 and the second camera 42 photograph two opposite surfaces of the electrode assembly 100 , respectively.

[0047] The first camera 41 and the second camera 42 of the photographing unit 4 may be line scan cameras, and the second image T2 output by the second camera 42 is equivalent to an expanded view of the electrode assembly 100 along the Y direction after winding.

[0048] Since the electrode assembly 100 is prone to shifting during winding, by comparing the first image T1 and the second image T2 of opposite sides of the electrode assembly 100 , it can be determined whether the first electrode sheet 1 and the second electrode sheet 2 are shifted during the winding process.

[0049] According to some embodiments of the present application, in the image matching step 220 , the (n+1)th second image T2 acquired in the image acquiring step 210 is matched with the nth first image T1 .

[0050] As described above, each time the winding needle 5 rotates through a preset angle α (e.g., α=360°), one first image T1 and one second image T2 are output, and the output first images T1 and second images T2 are counted. By setting the preset angle α to be less than or equal to 360°, it is ensured that each second image T2 and first image T1 has only one identification object 6. In addition, referring to Figure 1, the electrode assembly 100 in the output second image T2 is wound on the winding needle 5 earlier than the electrode assembly 100 in the first image T1. Furthermore, the identification object 6 is absent from the first image of the second image T2. Therefore, the (n+1)th second image T2 and the nth first image T1 are of the electrode assembly 100 of the same winding layer. Furthermore, it should be understood that the matching principle between the first image T1 and the second image T2 depends on the placement of the first camera 41 and the second camera 42 in the capturing unit 4. For example, when the first camera 41 and the second camera 42 are far apart, the (n+2)th second image T2 and the nth first image T1 may also match.

[0051] According to some embodiments of the present application, in the offset determination step 230, as shown in FIG. Figure 6 As shown, in a set of matching first images T1 and second images T2, a first distance d1 is obtained in the first image T1, and a second distance d2 is obtained in the second image T2. The first distance d1 is the distance from the first reference point A1 to the boundary of the first electrode 1, and the second distance is the distance from the second reference point A2 to the boundary of the second electrode 2. When the difference between the first distance d1 and the second distance d2 minus the preset distance between the boundary of the first electrode 1 and the boundary of the second electrode 2 is greater than the first threshold value, it is determined that the electrode assembly 100 is offset.

[0052] There is no restriction on the selection of the first reference point A1 and the second reference point A2, as long as there is a fixed correspondence between the first distance d1 determined by the first reference point A1 and the second distance d2 determined by the second reference point A2. Thus, by comparing the first distance d1 and the second distance d2, the relative positional relationship between the first electrode sheet 1 and the second electrode sheet 2 can be determined, thereby determining whether the electrode assembly 100 has shifted during winding.

[0053] According to some embodiments of the present application, in the offset determination step 230, in a set of matching first images T1 and second images T2, a first distance d1 is obtained in the first image T1, and a second distance d2 is obtained in the second image T2, the first distance d1 is the distance from the first reference point A1 to the boundary of the first electrode piece 1, and the second distance d2 is the distance from the second reference point A2 to the boundary of the second electrode piece 2. By comparing the first distance d1 and the first distance preset value d1_ref, it is determined whether the first electrode piece 1 of the electrode assembly 100 is offset, and by comparing the second distance d2 and the second distance preset value d2_ref, it is determined whether the second electrode piece 2 of the electrode assembly 100 is offset.

[0054] By comparing the first distance d1 and the second distance d2 with the preset values ​​respectively, it is possible to determine whether the first pole piece 1 and the second pole piece 2 have positional displacement. When it is determined that positional displacement has occurred, it is possible to more accurately determine which pole piece has positional displacement compared to determining the relationship between the first distance d1 and the second distance d2.

[0055] Alternatively, the relationship between the first distance d1 and the second distance d2 can be first determined to determine whether the electrode assembly 100 has shifted during winding. If it is determined that the electrode assembly 100 has shifted during winding, the first distance d1 is then compared with the first distance preset value d1_ref, and the second distance d2 is then compared with the second distance preset value d2_ref, thereby more accurately determining which electrode piece has shifted. If it is determined that the electrode assembly 100 has not shifted during winding, there is no need to proceed to the next step of shift determination, thereby improving the efficiency of shift determination.

[0056] According to some embodiments of the present application, an offset detection device is provided, which is used to detect the position offset of an electrode assembly 100 during winding, wherein the electrode assembly 100 includes a first electrode sheet 1 and a second electrode sheet 2, and the offset detection device includes: an image acquisition unit, which acquires a plurality of first images T1 and a plurality of second images T2 during the winding process of the electrode assembly 100, wherein the first image T1 includes the first electrode sheet 1, and the second image T2 includes the second electrode sheet 2; an image matching unit, which matches a first image T1 and a second image T2, wherein a first image T1 and a second image T2 contain the same or corresponding identification objects 6, and the identification objects 6 are parts periodically formed in each winding layer of the electrode assembly 100; and an offset determination unit, which determines, for a set of matched first images T1 and second images T2, whether the electrode assembly 100 is offset according to the boundary of the first electrode sheet in the first image and / or the boundary of the second electrode sheet in the second image. The offset detection device can determine the relative position relationship between the first electrode piece 1 and the second electrode piece 2 at the same position in the same winding layer, thereby more accurately determining whether the electrode assembly 100 has positional offset during the winding process.

[0057] According to some embodiments of the present application, see Figures 1 to 6 , the present application provides an offset detection method 100, comprising the following steps:

[0058] In the image acquisition step 210 , during the winding process of the electrode assembly 100 , each time the winding needle 5 rotates through a preset angle α, the photographing unit 4 acquires a first image T1 and a second image T2 . The first image T1 includes the first electrode sheet 1 before winding, and the second image T2 includes the second electrode sheet 2 after winding.

[0059] The image matching step 220 matches the (n+1)th second image T2 with the nth first image T1, thereby ensuring that the second electrode plate 2 on the (n+1)th second image T2 and the nth first image T1 are in the same winding layer of the electrode assembly 100, and the first image T1 and a second image T2 contain the same or corresponding identification objects 6 (first electrode tab 11 and / or second electrode tab 22).

[0060] In the offset determination step 230, first, an identification object 6 is identified in a set of matching first images T1 and second images T2, and a comparison area S is determined based on the identification object 6, thereby determining that the comparison area S of the first electrode 1 and the comparison area S of the second electrode 2 for offset determination are the same area of ​​the same winding layer of the electrode assembly 100. Then, a first reference point A1 and a second reference point A2 are defined in the comparison area, thereby obtaining a first distance d1 (the distance between the first reference point A1 and the boundary of the first electrode 1) and a second distance d2 (the distance between the second reference point A2 and the boundary of the second electrode 2). By comparing the difference between the distances d1 and d2 with the first threshold, it is determined whether the electrode assembly 100 has been offset. When it is determined that the electrode assembly 100 has been offset, d1 is further compared with the first distance preset value d1_ref and d2 and the second distance preset value d1_ref, so as to more accurately determine which electrode of the first electrode 1 and the second electrode 2 has been offset.

[0061] Finally, it should be noted that the present application is not limited to the above-described embodiments. The above-described embodiments are merely illustrative, and embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included within the technical scope of the present application. In addition, without departing from the scope of the present application, other methods of constructing the embodiments by applying various modifications that can be conceived by those skilled in the art and combining some of the constituent elements in the embodiments are also included within the scope of the present application.

Claims

1. A method for detecting an offset, characterized in that: The method is used to detect the positional deviation of an electrode assembly during winding, wherein the electrode assembly includes a first pole piece and a second pole piece, and the deviation detection method includes: an image acquisition step, during the winding process of the electrode assembly, acquiring a plurality of first images and a plurality of second images by a photographing unit, wherein the first image includes the first electrode sheet and the second image includes the second electrode sheet; an image matching step of matching one of the first images and one of the second images, wherein the matched first image and the second image contain the same or corresponding identification objects, and the identification objects are the tabs of the first pole piece and / or the tabs of the second pole piece in the same winding layer; An offset determination step is performed, in a set of matching first and second images, to determine whether the electrode assembly is offset based on the boundary of the first electrode piece in the first image and / or the boundary of the second electrode piece in the second image.

2. The method according to claim 1, characterized in that In the offset determination step, a comparison area is set according to the identification object, and whether the electrode assembly is offset is determined based on the boundary of the first electrode piece in the comparison area of ​​the first image and / or the boundary of the second electrode piece in the comparison area of ​​the second image.

3. The method according to claim 1, characterized in that The first image is an image of the electrode assembly before being wound on the winding needle, and the second image is an image of the electrode assembly after being wound on the winding needle.

4. The method according to claim 3, characterized in that In the image acquisition step, the first image and the second image are acquired when the winding needle rotates by a preset angle.

5. The method according to claim 1, wherein The shooting unit includes a first camera and a second camera; The first camera captures the first image, and the second camera captures the second image; The first camera and the second camera respectively photograph two opposite surfaces of the electrode assembly.

6. The method according to claim 1, characterized in that In the image matching step, the (n+1)th second image acquired in the image acquiring step is matched with the nth first image.

7. The method according to any one of claims 1 to 6, characterized in that In the offset determination step, in a set of matched first and second images, a first distance is obtained in the first image, and a second distance is obtained in the second image, where the first distance is a distance from a first reference point to a boundary of the first pole piece, and the second distance is a distance from a second reference point to a boundary of the second pole piece; When a difference between the first distance and the second distance minus a preset distance between the boundary of the first electrode piece and the boundary of the second electrode piece is greater than a first threshold, it is determined that the electrode assembly is offset.

8. The method according to any one of claims 1 to 6, characterized in that In the offset determination step, in a set of matched first and second images, a first distance is obtained in the first image, and a second distance is obtained in the second image, where the first distance is a distance from a first reference point to a boundary of the first pole piece, and the second distance is a distance from a second reference point to a boundary of the second pole piece; By comparing the first distance with a first distance preset value, determining whether the first pole piece is offset; By comparing the second distance with a second distance preset value, it is determined whether the second pole piece is offset.

9. A deviation detection device, characterized in that: Used to detect the positional deviation of an electrode assembly during winding, the electrode assembly comprising a first pole piece and a second pole piece, the deviation detection device comprising: an image acquisition unit, configured to acquire a plurality of first images and a plurality of second images during the winding process of the electrode assembly, wherein the first images include the first electrode sheet and the second images include the second electrode sheet; an image matching unit, matching one of the first images and one of the second images, wherein the matched one of the first image and the second image contain the same or corresponding identification objects, and the identification objects are the tabs of the first pole piece and / or the tabs of the second pole piece in the same winding layer; An offset determination unit determines, for a set of matching first and second images, whether the electrode assembly is offset according to a boundary of the first electrode piece in the first image and / or a boundary of the second electrode piece in the second image.

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