Misalignment detection method and device

Abstract

The present application provides a method and device for detecting a positional deviation when an electrode assembly is wound, the method and device including: an image acquisition step of acquiring a plurality of first images including a first pole piece and a plurality of second images including a second pole piece by a photographing unit during the winding process of the electrode assembly; an image matching step of matching one first image with one second image including the same or corresponding marked object formed periodically on each winding layer of the electrode assembly; and a deviation determination step of determining whether the electrode assembly has been shifted in the matched set of first and second images according to the boundary of the first pole piece in the first image and / or the boundary of the second pole piece in the second image. This makes it possible to determine the positional deviation of the first pole piece and the second pole piece at the same position on the same winding layer, and to determine the positional deviation more accurately.

Description

[Technical field]

[0001] The present application relates to the field of battery manufacturing, and more particularly to a method and device for detecting misalignment of an electrode assembly during winding and manufacturing of the electrode assembly. [Background technology]

[0002] An electrode assembly is a component that generates an electrochemical reaction in a battery cell, and is generally formed by winding or stacking a first pole piece, a second pole piece, and a separator. During the process of winding the electrode assembly, the first pole piece, the second pole piece, and the separator are prone to wobble, so that the first pole piece, the second pole piece, and the separator are displaced from their normal positions. The quality of the winding of the electrode assembly directly affects the performance of the battery cell. Therefore, how to accurately detect the displacement of the electrode assembly is extremely important in battery manufacturing. Summary of the Invention

[0003] In view of the above problems, the present invention provides a method and device for detecting deviations, which can accurately detect deviations in position when an electrode assembly is wound.

[0004] According to a first aspect, there is provided a misalignment detection method for detecting a positional misalignment when an electrode assembly including a first pole piece and a second pole piece is wound, the misalignment detection method including: an image acquisition step of acquiring a plurality of first images including the first pole piece and a plurality of second images including the second pole piece by a photographing unit during a winding process of the electrode assembly; an image matching step of matching one first image with one second image including the same or corresponding marked object formed periodically in each winding layer portion of the electrode assembly; and a misalignment determination step of determining whether the electrode assembly has been misaligned in the matched set of first and second images, depending on the boundary of the first pole piece in the first image and / or the boundary of the second pole piece 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 equipment and the position of the photographing unit, the first pole piece in the first image and the second pole piece in the second image acquired at the same time may not have a corresponding relationship with each other. That is, the second pole piece in the second image acquired at the same time may enter the electrode assembly winding equipment before the first pole piece in the first image. The technical solution of the embodiment of the present application ensures that the first pole piece and the second pole piece in the matched set of first and second images correspond to each other by matching the first and second images. That is, the first pole piece and the second pole piece in the matched set of first and second images are in the same winding layer of the electrode assembly after winding. Therefore, the position deviation during winding of the electrode assembly can be more accurately determined.

[0006] In some embodiments, in the deviation determination step, a comparison area is set according to the marking object, and whether the electrode assembly is deviation is determined according to the boundary of the first pole piece in the comparison area of ​​the first image and / or the boundary of the second pole piece in the comparison area of ​​the second image. The image matching step can ensure that the determined first image and second image are two images of the same winding layer. The comparison area determined by the marking object can further ensure that the area to be determined as deviation is the same area of ​​the first pole piece and the second pole piece stacked together in the same winding layer. This makes it possible to more accurately determine the deviation of the electrode assembly during winding.

[0007] In some embodiments, the first image is an image of the electrode assembly before it is wound around the winding needle, and the second image is an image of the electrode assembly after it is wound around the winding needle. During the process of winding around the winding needle, the pole piece is likely to become displaced. The first and second images provide the pre-winding and post-winding states of the pole piece, respectively, and can be used to determine whether the electrode assembly has become displaced during the winding process.

[0008] In some embodiments, the image acquisition step includes acquiring the first image and the second image when the winding needle rotates at a default angle. By setting the default angle, it is possible to ensure that each of the output first image and second image contains only one marked object, and to ensure that the comparison area can be determined by the marked object in the first image and the second image. In addition, since the image is acquired at the same time as the rotation, it is possible to perform a deviation judgment immediately.

[0009] In some embodiments, the photographing unit includes a first camera for photographing the first image and a second camera for photographing the second image, and the first camera and the second camera photograph two opposite sides of the electrode assembly, respectively. Since the electrode assembly 100 is easily misaligned during the process of being wound around the winding needle, by comparing the first image T1 and the second image T2 of the two opposite sides of the electrode assembly 100, it can be determined whether the first pole piece 1 and the second pole piece 2 are misaligned during the process of being wound around 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. Due to the influence of the winding speed of the electrode assembly winding equipment and the position of the photographing unit, etc., the electrode assembly in the second image acquired at the same time precedes the first electrode assembly in the first image, and there is no labeled object in the first drawing of the second image T2. By matching the (n+1)th second image with the nth first image, it can be ensured that the matched set of second images and the electrode assembly in the first image correspond to each other, that is, the first pole piece and the second pole piece in the matched set of first images and second images are in the same winding layer of the electrode assembly after winding, and the position deviation during winding of the electrode assembly can be more accurately determined.

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

[0012] In some embodiments, the step of determining the deviation includes obtaining a first distance from a first reference point to a boundary of the first pole piece in the first image and a second distance from a second reference point to a boundary of the second pole piece in the second image, and determining that the electrode assembly has been deviated if a difference between the first distance and the second distance minus a default distance between the boundary of the first pole piece and the boundary of the second pole piece is greater than a first threshold value. Thus, by comparing the first distance with the second distance, the relative positional relationship between the first pole piece and the second pole piece can be determined, and it can be determined whether the electrode assembly has been deviated when wound.

[0013] In some embodiments, the step of determining the deviation includes obtaining a first distance from a first reference point to a boundary of the first pole piece in the first image and a second distance from a second reference point to a boundary of the second pole piece in the second image, comparing the first distance with a default value of the first distance to determine whether the first pole piece of the electrode assembly has been deviated, and comparing the second distance with a default value of the second distance to determine whether the second pole piece of the electrode assembly has been deviated. Thus, by comparing the first distance and the second distance with the default values, respectively, it is possible to determine whether the first pole piece and the second pole piece have been deviated, and it is possible to more accurately determine which pole piece has been deviated, compared with determining the relationship between the first distance and the second distance.

[0014] According to a second aspect, there is provided a displacement detection device for detecting a positional deviation when an electrode assembly including a first pole piece and a second pole piece is wound, the displacement detection device including: an image acquisition unit for acquiring a plurality of first images including the first pole piece and a plurality of second images including the second pole piece during a winding process of the electrode assembly; an image matching unit for matching one first image with one second image including the same or corresponding marking objects that are formed periodically in each winding layer portion of the electrode assembly; and a displacement determination unit for determining whether the electrode assembly has been displaced for a matched set of first and second images, depending on the boundary of the first pole piece in the first image and / or the boundary of the second pole piece in the second image. [Brief description of the drawings]

[0015] The drawings described herein are intended to facilitate a better understanding of the present application and constitute a part of the present application, but the exemplary embodiments and the description thereof are used to interpret the present application and are not intended to unduly limit the present application.

[0016] [Figure 1] 1 is a schematic diagram including an electrode assembly manufacturing facility according to one embodiment of the present application. [Diagram 2] FIG. 2 is a schematic diagram of an electrode assembly after wrapping according to one embodiment of the present disclosure. [Diagram 3] FIG. 2 is a cross-sectional view including an XY cross section of an electrode assembly after winding according to one embodiment of the present application. [Figure 4] FIG. 2 is a schematic diagram of an electrode assembly according to one embodiment of the present application in an expanded state. [Diagram 5] 1 is a flowchart of a deviation detection method according to an embodiment of the present application. [Figure 6] FIG. 2 is a schematic diagram of a pair of matched first and second images according to one embodiment of the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, and not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without any creative effort are all within the scope of protection of the present application.

[0018] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by those skilled in the art. The terms used in this application are only for describing specific embodiments and are not intended to limit this application. The terms "comprise", "have" and any variations thereof in the description of this application, claims and drawings are intended to cover non-exclusive inclusion. The terms "first", "second", etc. in the description of this application, claims and drawings are not intended to describe a specific order or main and sub relationship, but are used to distinguish different objects.

[0019] An "embodiment" referred to in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiment may be included in at least one embodiment of this application. The phrases appearing in various places in the specification do not necessarily all refer to the same embodiment, nor are they separate or alternative embodiments that are mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments.

[0020] In the description of this application, unless otherwise clearly specified or limited, the terms "attachment," "connection," "connection," and "mounting" should be broadly understood. For example, they may be fixedly connected, detachably connected, or integrally connected. They may be directly connected, indirectly connected via an intermediate member, or internal communication between two elements. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific situation.

[0021] In this application, the term "and / or" is merely a correlation that describes related objects, and indicates that three types of relationships can exist. For example, A and / or B can indicate three cases: A exists alone, A and B exist together, and B exists alone. In this application, the character " / " generally indicates that the related objects before and after it are in an "or" relationship.

[0022] As used herein, the term "plurality" refers to two or more (including two). Similarly, a "set" refers to two or more (including two), and a "plurality" refers to two or more (including two).

[0023] FIG. 1 is a schematic diagram including an electrode assembly manufacturing facility according to an embodiment of the present application. FIG. 2 shows an electrode assembly 100 formed by winding. As shown in FIG. 1, the electrode assembly manufacturing apparatus includes a transport device and a winding device (winding needle 5). The transport device transports the strip-shaped first pole piece 1, second pole piece 2, and separator 3 to the winding device (winding needle 5), and the first pole piece 1, separator 3, second pole piece 2, and separator 3 are stacked in order and wound around the winding device (winding needle 5) to form an electrode assembly 100 (see FIG. 2). The winding needle 5 in FIG. 1 is merely an image, and the electrode assembly may be wound to have a cylindrical or elliptical cross section (as shown in FIG. 2 and FIG. 3) depending on the type of battery cell and the shape of the battery case.

[0024] When the winding needle 5 rotates once (360°), the electrode assembly 100 is increased by one layer. As shown in FIG. 2, the thickness of the electrode assembly 100 in the X direction gradually increases with the rotation of the winding needle 5. The widths of the strip-shaped first pole piece 1, second pole piece 2, and separator 3 determine the height of the electrode assembly 100 in the Z-axis direction. FIG. 3 is a cross-sectional view of the electrode assembly 100 in the XY plane shown in FIG. 2. As shown in FIG. 3, in each winding layer, the separator 3, the second pole piece 2, the separator 3, and the first pole piece 1 are arranged in this order from the outside to the inside in the X direction. As a result, in each winding layer, the separator 3 separates the second pole piece 2 and the first pole piece 1.

[0025] An important parameter in the process of winding the electrode assembly is the degree of alignment in the Z-axis direction of the electrode assembly 100 after winding. Specifically, the degree of alignment in the Z-axis direction of the electrode assembly 100 after winding is the relative position of the second pole piece 2 and the first pole piece 1 in the Z-axis direction. FIG. 4 is a development view of the electrode assembly 100 after stacking and winding along the Y-axis. As shown in the figure, in the Z-axis direction (i.e., the width direction of the electrode assembly 100 to be developed), the separator 3, the second pole piece 2, another separator 3, and the first pole piece 1 should be arranged in this order from outside to inside. That is, in the Z-axis direction, the separator 3 is located at the outermost position, the first pole piece 1 is located at the innermost position, and the second pole piece 2 is located at a predetermined distance beyond the first pole piece 1. In the process of winding the electrode assembly 100, the second pole piece 2 and the first pole piece 1 are likely to have a wobble phenomenon, which causes the relative positions of the second pole piece 2 and the first pole piece 1 to be misaligned, which affects the quality and performance of the manufactured battery cell. For this reason, the electrode assembly manufacturing apparatus further includes a photographing unit 4 to monitor the relative positional deviation between the second pole piece 2 and the first pole piece 1 .

[0026] In an ideal situation, the photographing unit photographs the electrode assembly 100 after winding, and identifies the second pole piece 2 and the first pole piece 1 in the obtained image to determine the relative positional relationship between the second pole piece 2 and the first pole piece 1. However, as described above, in each winding layer of the electrode assembly, in order to photograph the first pole piece 1, the separator 3, the second pole piece 2, and another separator 3 between the second pole piece 2 and the first pole piece 1 must be penetrated. Due to limitations of the conventional photographing unit, for example, the penetration ability of the infrared photographing unit is very limited, it is difficult to simultaneously identify the second pole piece 2 and the first pole piece 1 and determine their relative positional relationship in the image in which the electrode assembly 100 after winding is photographed. For this reason, it is necessary to determine the positional deviation of the pole pieces in the images in which the first pole piece 1 and the second pole piece 2 are photographed (corresponding to the first image T1 and the second image T2, respectively).

[0027] In order to photograph the first pole piece 1, it is necessary to use an image before winding (in this case, the second pole piece 2 and the two layers of separator 3 have not yet been laminated on the first pole piece 1). Also, as mentioned above, misalignment is likely to occur during the winding process. For this reason, the photograph in which the second pole piece 2 is photographed must use an image after winding. The first pole piece 1 in the first image T1 and the second pole piece 2 in the second image T2 obtained at the same time do not have a corresponding relationship with each other. That is, the second pole piece 2 in the second image T2 obtained at the same time enters the electrode assembly winding equipment (winding needle 5) before the first pole piece 1 in the first image T1. This raises the problem of how to accurately determine the relative misalignment between the second pole piece 2 and the first pole piece 1 by the photographing unit 4.

[0028] Based on the above consideration, the inventor has studied deeply and proposed a deviation detection method. Figure 5 is a flow chart of a deviation detection method according to an embodiment of the present application. As shown in Figure 5, the deviation detection method 200 includes an image acquisition step 210 of acquiring a plurality of first images T1 including the first pole piece 1 and a plurality of second images T2 including the second pole piece 2 by a photographing unit 4 during the winding process of the electrode assembly 100, an image matching step 220 of matching one first image T1 with one second image T2 including the same or corresponding marking object 6 periodically formed in each winding layer portion of the electrode assembly 100, and a deviation determination step 230 of determining whether the electrode assembly 100 has been deviated according to the boundary of the first pole piece 1 in the first image T1 and / or the boundary of the second pole piece 2 in the second image T2 in the matched pair of first image T1 and second image T2.

[0029] In order to compare the relative positions of the second pole piece 2 and the first pole piece 1 at the same position in the same winding layer of the electrode assembly 100 after winding using the first image T1 and the second image T2, in a method according to an embodiment of the present application, a marking object formed periodically in each winding layer of the electrode assembly 100 is defined. As a result, the first pole piece T1 and the second image T2 taken in each layer all contain the marking object.

[0030] By identifying the marked object, a pair of images T1, T2 in which the same or corresponding marked object is photographed are matched. The pair of matched images T1, T2 are used to perform the misalignment determination step 230. This ensures that what is determined in the misalignment determination step 230 is the first pole piece 1 and the second pole piece 2 at the same position in the same winding layer of the wound electrode assembly 100, and the misalignment of the electrode assembly 100 can be accurately determined.

[0031] According to some embodiments of the present application, as shown in Fig. 6, the marking object 6 is the tab 11 of the first pole piece 1 and / or the tab 22 of the second pole piece 2 in the same winding layer. Since the tab 11 of the first pole piece 1 and / or the tab 22 of the second pole piece 2 are periodically formed in each winding layer of the electrode assembly, there is no need to separately install a marking object on the electrode assembly 100, and the first image T1 and the second image T2 can be matched only by the tab 11 of the first pole piece and / or the tab 22 of the second pole piece. In addition, the marking object 6 is not limited to the tab 11 of the first pole piece 1 and the tab 22 of the second pole piece 2, but may be any object that can appear in each of the first image T1 and the second image T2.

[0032] According to some embodiments of the present application, in the deviation determination step, a comparison area S is set according to the marking object, and it is determined whether the electrode assembly 100 has been deviated according to the boundary of the first pole piece 1 in the comparison area S of the first image T1 and / or the boundary of the second pole piece 2 in the comparison area S of the second image T2.

[0033] As shown in FIG. 6, the distance of the comparison area S in the first image T1 from the labeled object 6 in the Y direction is equal to the distance of the comparison area S in the second image T2 from the same or corresponding labeled object 6. As a result, by ensuring that the labeled object 6 in the first image T1 and the labeled object 6 in the second image T2 correspond to each other, it is possible to ensure that the comparison area S in the first image T1 and the comparison area S in the second image T2 are in the same area of ​​the first pole piece 1 and the second pole piece 2 that are stacked together in the same winding layer. This makes it possible to more accurately determine the positional deviation during winding of the electrode assembly. In addition, the comparison area S is a partial area having a predetermined length in the Y direction. The predetermined length is smaller than the deployed length of the winding layer. The speed of deviation determination can be improved by determining the relative positional deviation between the first pole piece 1 and the second pole piece 2 in the predetermined length without determining the positional deviation in the entire deployed length.

[0034] According to some embodiments of the present application, the first image T1 is an image of the electrode assembly 100 before it is wound around the winding needle 5, and the second image T2 is an image of the electrode assembly 100 after it is wound around the winding needle 5.

[0035] As shown in FIG. 6, in the first image T1 in which the electrode assembly 100 before winding is photographed, the first pole piece 1 is located at the outermost position in the X-axis direction, and the separator 3, the second pole piece 2, and another separator 3 are located below the first pole piece 1 in this order. Depending on the transmission ability of the photographing unit 4, the first pole piece 1 and the separator 3 can be identified in the first image T1. In the second image T2 in which the electrode assembly 100 after winding is photographed, the separator 3 is located at the outermost position in the X-axis direction, and the separator 3 is located below the second pole piece 2, the other separator 3, and the first pole piece 1 in this order. Depending on the transmission ability of the photographing unit 4, the separator 3 and the second pole piece 2 can be identified in the second image T2. And, the first pole piece 1 in the first image T1 is the state of the electrode assembly 100 before winding, and the second pole piece 2 in the second image T2 is the state of the electrode assembly 100 after winding.

[0036] Since the electrode assembly 100 is prone to becoming displaced during the process of being wound around the winding needle, by comparing the second image T2, which shows the electrode assembly 100 after winding, with the first image T1, which shows the state of the electrode assembly 100 before winding, it is possible to determine whether the first pole piece 1 and the second pole piece 2 have become displaced during the winding process.

[0037] According to some embodiments of the present application, in an image acquisition step 210, a first image T1 and a second image T2 are acquired when the winding needle 5 rotates through a default angle α.

[0038] Please refer to Fig. 1. When the winding needle 5 rotates at a default angle α (for example, α = 360°), one first image T1 including the first pole piece 1 and one second image T2 including the second pole piece 2 are output. The angle of α is not limited to 360°, but it is sufficient to ensure that each of the output first image T1 and second image T2 includes only one same or corresponding marking target 6. In addition, since the images are acquired at the same time as the rotation, the deviation can be determined immediately.

[0039] According to some embodiments of the present application, referring to FIG. 1 , the photographing unit 4 includes a first camera 41 for photographing a first image T1 and a second camera 42 for photographing a second image T2, where the first camera 41 and the second camera 42 respectively photograph two opposite sides of the electrode assembly 100.

[0040] 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 from the second camera 42 corresponds to an expansion view along the Y direction of the electrode assembly 100 after winding.

[0041] Since the electrode assembly 100 is prone to shifting during the process of being wound around the winding needle, by comparing the first image T1 and the second image T2 of the two opposite sides of the electrode assembly 100, it is possible to determine whether the first pole piece 1 and the second pole piece 2 have shifted during the winding process.

[0042] According to some embodiments of the present application, in the image matching step 220, the (n+1)th second image T2 captured in the image capturing step 210 is matched with the nth first image T1.

[0043] As described above, when the winding needle 5 rotates at a default angle α (for example, α=360°), one first image T1 and one second image T2 are output, and the output first image T1 and second image T2 are counted. By setting the default angle α to be less than or equal to 360°, it is ensured that the labeled object 6 exists in each of the first image T2 and the first image T1, and that there is only one labeled object 6. Also refer to FIG. 1. The electrode assembly 100 in the output second image T2 is wound around the winding needle 5 before the electrode assembly 100 in the first image T1. And there is no labeled object 6 in the first image of the second image T2. Therefore, the (n+1)th second image T2 and the nth first image T1 are the electrode assembly 100 of the same winding layer. It should also be understood that the matching principle of the first image T1 and the second image T2 depends on the arrangement positions of the first camera 41 and the second camera 42 in the photographing unit 4. For example, when the first camera 41 and the second camera 42 are far apart, it is possible to match the (n+2)th second image T2 with the nth first image T1.

[0044] According to some embodiments of the present application, in the misalignment determination step 230, as shown in FIG. 6, in a matched pair of first and second images T1 and T2, a first distance d1 is obtained in the first image T1, which is the distance from the first reference point A1 to the boundary of the first pole piece 1, and a second distance d2 is obtained in the second image T2, which is the distance from the second reference point A2 to the boundary of the second pole piece 2. If the difference between the first distance d1 and the second distance d2 minus the default distance between the boundary of the first pole piece 1 and the boundary of the second pole piece 2 is greater than a first threshold, it is determined that the electrode assembly 100 has misaligned.

[0045] There is no restriction on the selection of the first reference point A1 and the second reference point A2, but there is only a certain correspondence relationship 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 pole piece 1 and the second pole piece 2 can be determined, and it can be determined whether the electrode assembly 100 has been misaligned during winding.

[0046] According to some embodiments of the present application, in the misalignment determination step 230, in a matched pair of first and second images T1 and T2, a first distance d1 is obtained in the first image T1, which is a distance from the first reference point A1 to the boundary of the first pole piece 1, and a second distance d2 is obtained in the second image T2, which is a distance from the second reference point A2 to the boundary of the second pole piece 2. By comparing the first distance d1 with a default value d1_ref of the first distance, it is determined whether the first pole piece 1 of the electrode assembly 100 has been misaligned, and by comparing the second distance d2 with a default value d2_ref of the second distance, it is determined whether the second pole piece 2 of the electrode assembly 100 has been misaligned.

[0047] By comparing the first distance d1 and the second distance d2, respectively, with default values, it can be determined whether the first pole piece 1 and the second pole piece 2 have respectively become misaligned. If it is determined that a misalignment has occurred, it can be more accurately determined which pole piece has become misaligned compared to determining the relationship between the first distance d1 and the second distance d2.

[0048] First, the relationship between the first distance d1 and the second distance d2 may be determined to determine whether the electrode assembly 100 is misaligned during winding. If it is determined that the electrode assembly 100 is misaligned during winding, the first distance d1 is compared with the default value of the first distance d1_ref, and the second distance d2 is compared with the default value of the second distance d2_ref to more accurately determine which pole piece is misaligned. If it is determined that the electrode assembly 100 is not misaligned during winding, there is no need to perform a next misalignment determination. This can improve the efficiency of the misalignment determination.

[0049] According to some embodiments of the present application, there is provided a deviation detection device for detecting a positional deviation when an electrode assembly 100 including a first pole piece 1 and a second pole piece 2 is wound, the deviation detection device including an image acquisition unit for acquiring a plurality of first images T1 including the first pole piece 1 and a plurality of second images T2 including the second pole piece 2 during the winding process of the electrode assembly 100, an image matching unit for matching one first image T1 with one second image T2 including the same or corresponding marked object 6 periodically formed on each winding layer of the electrode assembly 100, and a deviation determination unit for determining whether the electrode assembly 100 has been shifted according to the boundary of the first pole piece in the first image and / or the boundary of the second pole piece in the second image for the matched pair of first image T1 and second image T2. The deviation detection device can determine the relative positional relationship between the first pole piece 1 and the second pole piece 2 at the same position in the same winding layer, and can more accurately determine whether the electrode assembly 100 has been shifted during the winding process.

[0050] According to some embodiments of the present application, with reference to FIGS. 1 to 6, the present application provides a misalignment detection method 200, including an image acquisition step 210, an image matching step 220, and a misalignment determination step 230.

[0051] In the image acquisition step 210, when the winding needle 5 rotates at a default angle α during the winding process of the electrode assembly 100, the photographing unit 4 acquires a first image T1 including the first pole piece 1 before winding and a second image T2 including the second pole piece 2 after winding.

[0052] In the image matching step 220, the (n+1)th second image T2 is matched with the nth first image T1 to ensure that the second pole piece 2 in the (n+1)th second image T2 and the nth first image T1 are in the same winding layer in the electrode assembly 100, and that one first image T1 and one second image T2 include the same or corresponding labeled object 6 (first tab 11 and / or second tab 22).

[0053] In the deviation determination step 230, first, a marking object 6 is identified in the matched pair of the first image T1 and the second image T2, and a comparison area S is determined according to the marking object 6, thereby determining that the comparison area S of the first pole piece 1 determined to be deviation and the comparison area S of the second pole piece 2 are the same area of ​​the same winding layer in the electrode assembly 100. Then, a first reference point A1 and a second reference point A2 are defined in the comparison area to obtain a first distance d1 (the distance between the boundary between the first reference point A1 and the first pole piece 1) and a second distance d2 (the distance between the boundary between the second reference point A2 and the second pole piece 2). The difference between the distances d1 and d2 is compared with a first threshold value to determine whether the electrode assembly 100 has deviation. If it is determined that the electrode assembly 100 has deviation, d1 is further compared with a default value d1_ref of the first distance, and d2 is compared with a default value d1_ref of the second distance to more accurately determine which pole piece in the first pole piece 1 and the second pole piece 2 has deviation.

[0054] Finally, it should be explained that the present application is not limited to the above examples. The above examples are merely illustrative, and all examples that have substantially the same configuration as the technical ideas and exhibit the same effects within the scope of the technical means of the present application are included in the technical scope of the present application. In addition, various modifications that a person skilled in the art can make to the examples without departing from the spirit of the present application, and other embodiments constructed by combining some of the components in the examples are also included in the scope of the present application. [Explanation of symbols]

[0055] 100 Electrode Assembly 1 First pole piece 11 First Tab 2 Second pole piece 22 Second Tab 3. Separator 4. Shooting Unit 41 Camera No. 1 42 Second Camera 5 Winding needle 6. Labeling Target α Default angle T1 1st image T2 2nd image S comparison area A1 1st reference point A2 2nd reference point d1 First distance d2 2nd distance 200 Misalignment detection method 210 Image Acquisition Step 220 Image Matching Step 230 Deviation judgment step

Claims

1. A method for detecting misalignment when an electrode assembly including a first pole piece and a second pole piece is wound, comprising the steps of: an image capturing step of capturing a plurality of first images including the first pole piece and a plurality of second images including the second pole piece by a photographing unit during a winding process of the electrode assembly; an image matching step of matching a first image with a second image including the same or corresponding marking objects formed periodically on portions of each winding layer of the electrode assembly; and determining whether the electrode assembly is misaligned in a matched pair of first and second images according to a boundary of a first pole piece in the first image and / or a boundary of a second pole piece in the second image, The marking object is a tab of the first pole piece and / or a tab of the second pole piece in the same winding layer; A method for detecting a deviation.

2. In the deviation determination step, a comparison area is set according to the marking object, and whether the electrode assembly is deviation is determined according to a boundary of a first pole piece in the comparison area of ​​the first image and / or a boundary of a second pole piece in the comparison area of ​​the second image.

2. The method of claim 1 .

3. the first image is an image of the electrode assembly before it is wound around a winding needle, and the second image is an image of the electrode assembly after it is wound around the winding needle.

3. The method according to claim 1 or 2.

4. In the image acquisition step, the first image and the second image are acquired when the winding needle rotates at a default angle.

4. The method according to claim 3 .

5. the photographing unit includes a first camera that photographs the first image and a second camera that photographs the second image; the first camera and the second camera respectively photograph two opposite sides of the electrode assembly; The method according to any one of claims 1 to 4.

6. In the image matching step, a (n+1)th second image acquired in the image acquisition step is matched with the nth first image. The method according to any one of claims 1 to 5.

7. In the deviation determination step, In a matched pair of first and second images, a first distance is obtained in the first image, the first distance being a distance from a first reference point to a boundary of the first pole piece, and a second distance is obtained in the second image, the second distance being a distance from a second reference point to a boundary of the second pole piece; determining that the electrode assembly has shifted if a difference between the first distance and the second distance minus a default distance between the boundary of the first pole piece and the boundary of the second pole piece is greater than a first threshold value; The method according to any one of claims 1 to 6.

8. In the deviation determination step, In a matched pair of first and second images, a first distance is obtained in the first image, the first distance being a distance from a first reference point to a boundary of the first pole piece, and a second distance is obtained in the second image, the second distance being a distance from a second reference point to a boundary of the second pole piece; determining whether a first pole piece of the electrode assembly has shifted by comparing the first distance with a default value for the first distance; determining whether a second pole piece of the electrode assembly has shifted by comparing the second distance with a default value for the second distance; The method according to any one of claims 1 to 6.

9. A displacement detection device for detecting a positional displacement when an electrode assembly including a first pole piece and a second pole piece is wound, the device comprising: an image capture unit for capturing a plurality of first images including the first pole piece and a plurality of second images including the second pole piece during a winding process of the electrode assembly; an image matching unit for matching a first image with a second image including the same or corresponding marking objects periodically formed on portions of each winding layer of the electrode assembly; a deviation determination unit for determining whether the electrode assembly is deviation based on a boundary of a first pole piece in the first image and / or a boundary of a second pole piece in the second image for a pair of matched first and second images; The marking object is a tab of the first pole piece and / or a tab of the second pole piece in the same winding layer; A deviation detection device comprising:

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