Welding mark detection system, welding mark detection method and current collector production method

Abstract

The invention discloses a welding mark detection system, a welding mark detection method and a current collector production method, and relates to the technical field of battery cell manufacturing. The welding mark detection system comprises a front light source, a backlight roller, a first camera and an upper computer, and the front light source is used for irradiating a tab welding area from the front face of the current collector so that a welding mark structure can be brightened and the tab welding area outside the welding mark structure can be darkened; the backlight roller is used for irradiating the film area from the back face of the collector piece, and the back face and the front face are oppositely arranged. The first camera is used for acquiring a first image from the front side, and the first image at least comprises an image of the welding printing structure and an image of the through hole; the upper computer is used for enabling the first camera to acquire a first image based on the front light source irradiating the tab welding area and the backlight roller irradiating the film area, so that the contrast ratio of the tab welding area except the welding printing structure in the first image and the film area is enhanced, and the detection success rate of the edge of the tab welding area is improved.

Description

Technical Field

[0001] This application relates to the field of battery cell manufacturing technology, and in particular to a solder mark detection system, a solder mark detection method, and a current collector production method. Background Technology

[0002] A lithium-ion battery cell typically includes a positive current collector, a negative current collector, and a separator between them. The positive current collector typically includes a positive current collector layer (usually an aluminum foil or a composite foil containing an aluminum layer) and an active material layer coated on the positive current collector layer. The negative current collector typically includes a negative current collector layer (usually a copper foil or a composite foil containing a copper layer) and an active material layer coated on the negative current collector layer. The positive active material includes lithium nickel cobalt manganese oxide and lithium nickel cobalt aluminum oxide, etc., and the negative active material includes graphite or graphite-like carbon, etc.

[0003] After the positive and negative current collectors are coated with active materials and rolled to form electrode sheets, some technologies use connection methods such as ultrasonic roll welding on the electrode sheets to connect the adapter sheets in order to form electrode tabs. At this time, a solder mark structure will be formed. In related technologies, one side of the solder mark structure is a near-rectangular depression, and the other side of the solder mark structure is a near-elliptical protrusion.

[0004] In related technologies, visual inspection is typically used to detect the distance between the solder joint and the active material layer, the overall width of the solder joint, or the number of solder joints. However, sometimes it is difficult to determine the edges of the solder joint, and the success rate of detection needs to be improved. Summary of the Invention

[0005] The main purpose of this application is to propose a solder mark inspection system aimed at improving the inspection success rate.

[0006] To achieve the above objectives, the solder mark inspection system proposed in this application is used to inspect current collectors of lithium batteries. The current collector includes a film region and a tab welding region. The film region has multiple through holes, and the tab welding region has a solder mark structure. The solder mark inspection system includes: a front light source, a backlight roller, a first camera, and a host computer. The front light source is used to illuminate the tab welding region from the front of the current collector, so that the solder mark structure is illuminated and the tab welding region outside the solder mark structure is darkened. The backlight roller is used to support the back of the current collector and illuminate the film region from the back of the current collector. The first camera is used to acquire a first image from the front of the current collector. The first image includes at least an image of the solder mark structure and an image of the through holes. The host computer is used to enable the first camera to acquire the first image based on the front light source illuminating the tab welding region and the backlight roller illuminating the film region.

[0007] Related technologies typically place a light source and camera on the front of the current collector. The light source illuminates the solder structure while darkening the transition piece outside the solder structure. A bright area is formed between the solder structure and the active material layer on the current collector layer, allowing for visual image inspection of the solder structure. However, some current collectors have changed their active material area from an opaque solid structure to through-holes with mesh-like openings (e.g., the negative electrode current collector layer uses multi-microporous copper foil), and the transition piece covers the active material layer. In this case, most light passes through the through-holes without reflecting back to the camera, resulting in darkness of the transition piece outside the solder structure and the film area containing the active material layer, leading to insufficient image contrast. The boundary between the transition piece and the active material layer is also dark, making it difficult to determine the edge condition of the solder structure. Because the micropores on the current collector layer (such as copper foil) and the mesh-like openings on the active material area are relatively small, it is usually difficult to detect light passing through without reflecting back to the camera.

[0008] The solder mark detection system in this application illuminates the tab welding area from the front of the current collector, making the solder mark structure bright and the tab welding area outside the solder mark structure dark. The backlight roller illuminates the film area from the back of the current collector, making the film area bright. This enhances the contrast between the tab welding area outside the solder mark structure and the film area in the first image acquired by the first camera from the front, thereby improving the detection success rate of the edge of the tab welding area.

[0009] In addition, the host computer uses the front light source to illuminate the tab welding area and the backlight roller to illuminate the film area to enable the first camera to acquire the first image, so that the first image can simultaneously contain the image of the tab welding area and the image of the soldering structure, reducing the number of shots required overall and improving the detection efficiency.

[0010] Optionally, the backlight roller includes a cylindrical body and a light-emitting element, the light-emitting element being at least partially disposed within the cylindrical body, the cylindrical body being used to abut against the back of the current collector; the cylindrical body is at least partially made of a light-transmitting material so that the light from the light-emitting element illuminates the film area.

[0011] At this point, the cylinder can support the collector plate by abutting against the back of the collector plate, and can also reduce the overall space occupied by the solder stamp detection system by setting the light source at least partially inside the cylinder, and reduce the risk of the light source being damaged by external objects.

[0012] Optionally, the solder mark detection system further includes a traction roller for supporting the collector plate and pulling the collector plate forward; and / or, the light source is configured as a linear light source, the light rays of the light source are parallel to the axis of the cylinder, and the cylinder is made of a light-diffusing material.

[0013] At this point, the collector plate can be propelled forward by the traction roller, reducing the power output requirement of the backlight roller on the collector plate and lowering the friction requirement between the cylinder and the collector plate, making the cylinder manufacturing process more flexible and convenient. The cylinder is made of a light-diffusing material, which allows the light emanating from the light source onto the cylinder to be transmitted outward evenly, thus uniformly illuminating the aforementioned film area and the tab welding area.

[0014] Optionally, the solder stamp detection system further includes a stroke sensor for detecting the rolling stroke of the cylinder; the host computer is used to enable the first camera to acquire the first image based on the rolling stroke and a preset correspondence.

[0015] At this time, since the shooting range of the first image device has a certain width, the host computer enables the first camera to acquire the first image according to the rolling stroke and the preset correspondence, which can reduce the number of shots taken by the first image device and improve the automation level of the solder stamp detection system.

[0016] Optionally, the collector plate is used to move along the circumferential direction of the cylinder, and the first camera includes a line scan camera, the line scan line of the line scan camera being parallel to the axial direction of the cylinder.

[0017] At this time, since the solder mark structure is usually formed on the side of the transport direction of the collector plate, the line scan line of the line scan camera is parallel to the axial direction of the cylinder, which is beneficial to improve the concentration of the line scan line and reduce the equipment cost of imaging.

[0018] Optionally, the solder stamp inspection system includes at least two first cameras arranged along the axial direction of the cylinder; along the transport direction of the collector plate, the electrode welding areas are respectively provided on both sides of the membrane area, and the two first cameras are used to acquire images of the electrode welding areas and the adjacent through holes respectively.

[0019] At this time, the first camera is arranged along the axial direction of the cylinder, which is beneficial to improve the detection efficiency of the current collectors with electrode welding areas on both sides.

[0020] Optionally, the solder stamp inspection system further includes a second camera, which is spaced apart from the first camera along the transport direction of the current collector; the second camera is used to acquire a second image from the front of the current collector, the second image including at least an image of the film area; the host computer is used to enable the second camera to acquire the second image based on the backlight roller illuminating the film area.

[0021] At this time, the solder stamp inspection system can acquire a second image through the second camera, so as to detect the forming quality of the film area based on the second image; in addition, the backlight roller can be used to acquire the first image and the second image at the same time, which improves the utilization rate of the backlight roller and improves the simplification of the solder stamp inspection system.

[0022] Optionally, the collector plate is used for transporting along the circumferential direction of the cylinder, and the second camera and the first camera are spaced apart along the circumferential direction of the cylinder; the cylinder includes a first light-transmitting area and a second light-transmitting area arranged along the circumferential direction of the cylinder, the first light-transmitting area is used to be arranged opposite to the first camera, and the second light-transmitting area is used to be arranged opposite to the second camera.

[0023] At this time, the second camera and the first camera are set at intervals along the circumferential direction of the cylinder. This not only reduces mutual shooting interference by spacing them out, but also covers the light-emitting surface of the backlight roller to a greater extent, further improving the utilization rate of the backlight roller and reducing the backlight roller's exposure to external light and interference.

[0024] This application also proposes a solder mark detection method for detecting current collectors in lithium batteries. The current collector includes a film region and a tab welding region. The film region has multiple through holes, and the tab welding region has solder mark structures. The solder mark detection method includes the following steps: The electrode welding area is illuminated from the front of the current collector so that the solder pattern is illuminated and the electrode welding area outside the solder pattern is darkened. The membrane region is illuminated from the back of the current collector; A first image is obtained from the front of the current collector, the first image including at least an image of the solder pattern and an image of the through hole.

[0025] The solder mark detection method in this application can illuminate the electrode welding area from the front of the current collector, making the solder mark structure bright and the electrode welding area outside the solder mark structure dark, and illuminate the film area from the back of the current collector, thereby enhancing the contrast between the electrode welding area outside the solder mark structure and the film area in the first image acquired by the first camera from the front, and improving the detection success rate of the electrode welding area edge.

[0026] Furthermore, by acquiring a first image while irradiating the tab welding area and the irradiated film area, the first image can simultaneously contain an image of the tab welding area and an image of the solder pattern, reducing the number of shots and improving detection efficiency.

[0027] Optionally, the step of acquiring a first image from the front of the current collector includes: The rolling stroke of the detection cylinder is used to abut against the back side of the collector plate; The first image is obtained based on the scrolling stroke and the preset correspondence.

[0028] At this time, since the first image has a certain width, the first image is obtained according to the scroll stroke and the preset correspondence, which can reduce the number of shots taken by the first image device and improve the automation level of the solder stamp detection method.

[0029] Optionally, the solder mark detection method further includes the following steps: At least two first cameras are provided, arranged along the axial direction of the cylinder, which is used to abut the back of the current collector; along the transport direction of the current collector, the electrode tab welding area is provided on both sides of the membrane region; The step of acquiring a first image from the front of the current collector includes: Images of the electrode welding area and the adjacent through hole are acquired respectively.

[0030] At this time, the images of the electrode welding area and the adjacent through hole are obtained by arranging the first camera along the axial direction of the cylinder, which is beneficial to improve the detection efficiency of the current collector with electrode welding areas on both sides.

[0031] Optionally, the solder mark detection method further includes the following steps: Based on the first image, obtain the first boundary line of the through hole, with the first boundary line facing the electrode welding area; Based on the first image, obtain the second boundary line of the solder mark structure, the second boundary line facing the film region; The distance from the solder mark structure to the first boundary line is obtained based on the image parameters corresponding to the first boundary line, the second boundary line, and the first image.

[0032] At this time, the solder stamp detection method can improve the detection efficiency of the distance from the solder stamp structure to the first boundary line by using the image parameters corresponding to the first boundary line, the second boundary line, and the first image, which is conducive to discovering possible distance anomalies in the solder stamp structure as early as possible.

[0033] Optionally, the image parameters corresponding to the first image include pixel precision; The step of obtaining the distance from the solder mark structure to the first boundary line based on the first boundary line, the second boundary line, and the image parameters corresponding to the first image includes: The distance from the solder pattern to the first boundary line is obtained based on the pixel precision and the number of pixels between the first boundary line and the second boundary line.

[0034] At this point, obtaining the distance from the solder pattern to the first boundary line based on the pixel precision and the number of pixels between the first and second boundary lines is beneficial for improving detection efficiency.

[0035] Optionally, the solder mark detection method further includes the following steps: Based on the first image, a second boundary line and a third boundary line of the solder pattern are obtained, wherein the second boundary line faces the film region and the third boundary line faces away from the film region. The distance between the second boundary line and the third boundary line is obtained based on the image parameters corresponding to the second boundary line, the third boundary line, and the first image.

[0036] At this point, the solder stamp detection method can improve the detection efficiency of the overall width of the solder stamp structure by using the image parameters corresponding to the second boundary line, the third boundary line and the first image, which is beneficial to detect possible abnormalities in the overall width of the solder stamp structure as early as possible.

[0037] Optionally, the image parameters corresponding to the first image include pixel precision; The step of obtaining the distance between the second boundary line and the third boundary line based on the second boundary line, the third boundary line, and the image parameters corresponding to the first image includes: The distance between the second boundary line and the third boundary line is obtained based on the pixel precision and the number of pixels between the second boundary line and the third boundary line.

[0038] At this point, obtaining the distance between the second and third boundary lines based on pixel precision and the number of pixels between the second and third boundary lines is beneficial for improving detection efficiency.

[0039] Optionally, the solder mark detection method further includes the following steps: The number of the solder marks is obtained based on the first image and the first preset recognition model.

[0040] At this point, the solder stamp detection method can improve the detection efficiency of the number of solder stamp structures by using the first image and the first preset recognition model.

[0041] Optionally, before the step of obtaining the number of solder marks based on the first image and the first preset recognition model, the solder mark detection method further includes the following steps: At least one first training image is obtained from the front of the current collector being illuminated, the first training image including at least an image of the solder pattern; The number of solder marks in the first training image is labeled. The first preset recognition model is formed based on the first training image after numerical labeling.

[0042] At this point, the solder stamp detection method can form a more accurate first preset recognition model through the first training image and the number of solder stamp structures, which is beneficial to improve the detection accuracy through the first preset recognition model.

[0043] Optionally, the solder mark detection method further includes the following steps: A second image is acquired from the front of the current collector based on the irradiation of the membrane region, the second image including at least an image of the membrane region.

[0044] At this point, the solder stamp inspection method can detect the forming quality of the film area by acquiring the second image; in addition, the solder stamp inspection method can simultaneously acquire the first image and the second image based on the irradiation of the film area, thereby improving the inspection efficiency.

[0045] Optionally, the solder mark detection method further includes the following steps: Based on the second image and the second preset recognition model, obtain the folds or seams in the second image.

[0046] At this point, the solder mark detection method can improve the detection efficiency of wrinkles or joints in the film area by using the second image and the second preset recognition model.

[0047] This application also proposes a method for manufacturing current collectors, the method comprising the following steps: A current collector for preparing a lithium battery is provided, the current collector comprising a film region and a tab welding region, the film region having multiple through holes and the tab welding region having a solder mark structure; For at least a portion of the current collectors prepared, the tab welding area is illuminated from the front of the current collectors so that the solder pattern is illuminated and the tab welding area outside the solder pattern is darkened. The membrane region is illuminated from the back of the current collector; A first image is obtained from the front of the current collector, the first image including at least an image of the solder pattern and an image of the through hole.

[0048] The current collector production method in this application, when in use, can make the soldering structure bright and the soldering area outside the soldering structure dark by irradiating the tab welding area from the front of the current collector, and make the film area bright by irradiating the film area from the back of the current collector, thereby enhancing the contrast between the tab welding area outside the soldering structure and the film area in the first image acquired by the first camera from the front, and improving the detection success rate of the edge of the tab welding area.

[0049] Furthermore, by acquiring a first image while irradiating the tab welding area and the irradiated film area, the first image can simultaneously contain an image of the tab welding area and an image of the solder pattern, reducing the number of shots and improving detection efficiency.

[0050] Optionally, the steps for fabricating the current collector of a lithium battery include: The through holes are arranged in a plurality of arrays; Multiple solder patterns are formed, and the arrangement direction of the solder patterns is parallel to the arrangement direction of the through holes.

[0051] At this point, the current collector manufacturing method can improve the detection efficiency of the distance of the solder pattern by making the arrangement direction of the solder pattern parallel to the arrangement direction of the through hole, so that the through hole can be used as a positioning reference for the solder pattern. Attached Figure Description

[0052] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0053] Figure 1 This is a top view of an embodiment of a solder stamp inspection system in the related art; Figure 2 Images of the current collector of the entire entity obtained by related technologies; Figure 3 This is a test image of a current collector with a through hole, based on relevant technologies. Figure 4 for Figure 3 A magnified view of a portion of the membrane region on a CIMC wafer. Figure 5 This is a top view of an embodiment of the solder stamp inspection system provided in this application; Figure 6 Left view of an embodiment of the solder stamp inspection system provided in this application; Figure 7 This is a schematic diagram illustrating changes in the detected image in one embodiment of this application; Figure 8 This is a schematic diagram of the structure of the detected image in one embodiment of this application; Figure 9 This is a schematic diagram of the structure of another detection image in one embodiment of this application; Figure 10 This is a rendering of another detection image in one embodiment of this application; Figure 11This is a schematic diagram of the structure of another detection image in one embodiment of this application; Figure 12 This is a rendering of another detection image in one embodiment of this application; Figure 13 A schematic diagram of the steps of an embodiment of the solder mark detection method provided in this application; Figure 14 This is a schematic diagram of the steps of another embodiment of the solder mark detection method provided in this application.

[0054] Explanation of icon numbers: 100. Current collector; 110. Membrane area; 120. Electrode welding area; 121. Welding structure; 210. Front light source; 220. Light emitter; 230. First camera; 240. Cylinder; 250. Second camera; 260. Mounting bracket.

[0055] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0056] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0057] It should be noted that if the embodiments of this application involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0058] Furthermore, if the embodiments of this application involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution that simultaneously satisfies A and B. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed in this application.

[0059] A lithium-ion battery cell typically includes a positive current collector, a negative current collector, and a separator between them. The positive current collector typically includes a positive current collector layer (usually an aluminum foil or a composite foil containing an aluminum layer) and an active material layer coated on the positive current collector layer. The negative current collector typically includes a negative current collector layer (usually a copper foil or a composite foil containing a copper layer) and an active material layer coated on the negative current collector layer. The positive active material includes lithium nickel cobalt manganese oxide and lithium nickel cobalt aluminum oxide, etc., and the negative active material includes graphite or graphite-like carbon, etc.

[0060] After the positive and negative current collectors are coated with active materials and rolled to form electrode sheets, some technologies use connection methods such as ultrasonic roll welding on the electrode sheets to connect the adapter sheets in order to form electrode tabs. At this time, a solder mark structure will be formed. In related technologies, one side of the solder mark structure is a near-rectangular depression, and the other side of the solder mark structure is a near-elliptical protrusion.

[0061] In related technologies, visual inspection is typically used to detect the distance between the solder joint and the active material layer, the overall width of the solder joint, or the number of solder joints. However, sometimes it is difficult to determine the edges of the solder joint, and the success rate of detection needs to be improved.

[0062] Therefore, based on the above considerations, in order to improve the detection success rate, this application proposes a solder stamp detection system. In use, this system illuminates the tab welding area from the front of the current collector, making the solder stamp structure bright and the area outside the solder stamp structure dark, while a backlight roller illuminates the film area from the back of the current collector, making the film area bright. This enhances the contrast between the tab welding area outside the solder stamp structure and the film area in the first image acquired by the first camera from the front, thereby improving the detection success rate of the tab welding area edge.

[0063] Figure 1 A top view of an embodiment of a solder joint inspection system in the related art is shown. In the related art, a light source 210a and a camera 230a are typically arranged on the front side of the current collector 120a, for example, both the light source 210a and the camera 230a are arranged on the upper side of the current collector 120a. (Refer to...) Figure 1 and Figure 2 The related technology uses a light source 210a to illuminate the solder structure 121a and darken the adapter piece 120a outside the solder structure 121a. Furthermore, the solder structure 121a and the active material layer (the active material layer can be understood as a film region, see reference) on the current collector layer... Figure 2 The space between the two sides forms a bright area, thereby performing image visual inspection on the solder pattern 121a.

[0064] However, the active material region of some current collectors consists of an opaque, solid structure (see reference). Figure 2The diagram shows a replacement with through-holes in the form of mesh or similar structures (e.g., using porous copper foil in the negative electrode current collector), and the adapter sheet is covered with an active material layer; for example... Figure 3 The current collector 100 shown includes a membrane region 110 (e.g., a region coated with an active material layer) and a tab welding region 120 (e.g., the region where the adapter plate is located). The membrane region 110 and the tab welding region 120 are arranged along the surface of the current collector 100. The membrane region 110 is provided with a plurality of through holes that penetrate the thickness of the current collector 100. The tab welding region 120 is provided with a solder mark structure 121 (e.g., a solder mark).

[0065] At this time, most of the light passes through the through-hole without being reflected back to the camera, causing the tab welding area 120 outside the solder structure 121 and the film area 110 where the active material layer is located to be darkened, resulting in insufficient image contrast. The boundary between the tab welding area 120 and the film area 110 where the active material layer is located is also darkened, making it difficult to determine the edge conditions of the solder structure 121 and the tab welding area 120. Because the through-holes in the current collector layer such as copper foil and the mesh-like holes in the active material area are relatively small, for example, refer to… Figure 3 and Figure 4 The ratio of the diameter of the through hole on the current collector layer to the diameter of the envelope circle of the solder pattern 121 is less than or equal to 0.1. In some products, this ratio is less than or equal to 0.05, or even less than 0.01. Therefore, it is usually difficult to detect that light passes through without being reflected back to the camera.

[0066] The structure of the solder stamp inspection system proposed in this application will now be explained using specific embodiments. In one embodiment of this application, referring to... Figure 5 and Figure 6 The solder mark inspection system is used to inspect a current collector 100, which includes a film region 110 and a tab welding region 120, arranged along the surface of the current collector 100. The film region 110 has multiple through holes that penetrate the thickness of the current collector 100. The tab welding region 120 has a solder mark structure 121. The solder mark inspection system includes a front light source 210, a backlight roller, a first camera 230, and a host computer. The front light source 210 is used to illuminate the tab welding region from the front of the current collector 100. 120, so that the soldering structure 121 is illuminated and the tab welding area 120 outside the soldering structure 121 is darkened; the backlight roller is used to support the back of the current collector 100 and irradiate the film area 110 from the back of the current collector 100; the first camera 230 is used to acquire a first image from the front of the current collector 100, the first image including at least an image of the soldering structure 121 and an image of the through hole; the host computer is used to enable the first camera 230 to acquire the first image based on the front light source 210 irradiating the tab welding area 120 and the backlight roller irradiating the film area 110.

[0067] The current collector 100 can be a single positive or negative electrode film; it can also be two or more stacked positive or negative electrode films, for example, two or more positive or negative electrode films can be stacked together for detection. The first camera 230 can be a line scan camera or a CCD (Charge Coupled Device) camera, etc., and this embodiment does not limit it.

[0068] The front and back sides of the current collector 100 can be understood as the two relatively large surfaces of the current collector 100, for example... Figure 5 and Figure 6 The front and back are positioned facing up and down, respectively. (Refer to...) Figure 5 and Figure 6 (in Figure 5 , Figure 6 The images show a top view and a left view of an embodiment of the solder stamp inspection system provided in this application. The front light source 210 is used to illuminate the tab welding area 120 from the upper side of the current collector 100, so that the solder stamp structure 121 is illuminated and the tab welding area 120 outside the solder stamp structure 121 is darkened. Specifically, the reflection or diffuse reflection characteristics of the solder stamp structure 121 and the tab welding area 120 outside the solder stamp structure 121 can be combined, and the light angle of the front light source 210 can be adjusted to make the solder stamp structure 121 illuminated and the tab welding area 120 outside the solder stamp structure 121 darkened. It can be understood that because the solder stamp structure 121 has protrusions or depressions, the solder stamp structure 121 is more likely to reflect light in all directions, so the solder stamp structure 121 is more easily illuminated than the tab welding area 120 outside the solder stamp structure 121. The backlight roller is used to illuminate the film area 110 from below the collector plate 100, so that the light from the backlight roller passes through the through hole on the film area 110 and reaches the first camera 230.

[0069] The host computer can be set as a terminal device, such as a computer, a PLC (Programmable Logic Controller), etc. The host computer is used to enable the first camera 230 to acquire the first image based on the front light source 210 illuminating the tab welding area 120 and the backlight roller illuminating the film area 110; that is, the host computer can be set to enable the first camera 230 to acquire the first image when the front light source 210 illuminates the tab welding area 120 and the backlight roller illuminating the film area.

[0070] in, Figure 7 A schematic diagram illustrating changes in the detected image is shown in one embodiment of this application. (Refer to...) Figure 7The current collector 100 includes a membrane region 110 (the membrane region 110 can be understood as a region that transmits light due to through holes, mesh holes, or similar perforations) arranged along the membrane surface of the current collector 100, and an electrode tab welding region 120, on which the aforementioned solder mark structure 121 is provided. For example, refer to... Figure 6 and Figure 7 The collector plate 100 can be configured to transport along the Y-axis direction; refer to Figure 7 and Figure 8 The membrane region 110 and the tab welding region 120 are arranged along the X-axis. It can be understood that the tab welding region 120 is located on the side of the membrane region 110 along the conveying direction of the current collector 100; wherein, along the conveying direction of the current collector 100, the membrane region 110 can be provided on both sides of the tab welding region 120.

[0071] In this configuration, an adapter piece can be connected to the membrane region 110 where the active material layer is located to form a tab, and multiple solder structures 121 are formed during the connection process; at this time, the tab soldering region 120 includes the region where the adapter piece is located. Furthermore, the tab soldering region 120 where the adapter piece is located can either cover the membrane region 110 where the active material layer is located, or the edge of the tab soldering region 120 where the adapter piece is located can abut against the edge of the membrane region 110 where the active material layer is located. This can be understood as the membrane region 110 being connected to the tab soldering region 120.

[0072] The solder joint detection system in this application, when in use, illuminates the tab welding area 120 from the front of the current collector 100 using a front light source 210, causing the solder joint structure 121 to light up and the tab welding area 120 outside the solder joint structure 121 to darken. Meanwhile, a backlight roller illuminates the film area 110 from the back of the current collector 100, causing the film area 110 to light up. This enhances the contrast between the tab welding area 120 outside the solder joint structure 121 and the film area 110 in the first image acquired by the first camera 230 from the front, thereby improving the detection success rate of the tab welding area 120 edge. For example, see reference... Figure 7 The detection image obtained by the related technology on the left side of the figure is changed to the detection image obtained by the above-described embodiment of this application on the right side of the figure; after the change, the contrast between the tab welding area 120 and the film area 110 outside the soldering structure 121 is enhanced, and the boundary between the tab welding area 120 and the film area 110 is more obvious.

[0073] In addition, the host computer uses the front light source 210 to illuminate the tab welding area 120 and the backlight roller to illuminate the film area 110, so that the first image can simultaneously include the image of the tab welding area 120 and the image of the soldering structure 121, reducing the number of shots required and improving the detection efficiency.

[0074] Continue to refer to Figure 5 and Figure 6In some embodiments, the backlight roller includes a cylinder 240 and a light-emitting element 220, the cylinder 240 being used to abut against the back of the collector plate 100, for example... Figure 6 The middle cylinder 240 abuts against the lower surface of the collector plate 100. The cylinder 240 can be understood as a cylinder capable of rolling and rotating, for example, along... Figure 6 The U-direction rotation of the current collector 100 causes it to move relative to the current collector 100 during the transport process, or to drive the current collector 100 to move, or to be driven by the current collector 100 to move.

[0075] In some embodiments, the solder stamp inspection system may further include a traction roller, which supports the collector plate 100 and pulls it forward. In this case, the collector plate 100 can be propelled forward by the traction roller, reducing the power output requirement of the backlight roller on the collector plate and lowering the frictional requirements between the cylinder 240 and the collector plate 100, making the preparation of the cylinder 240 more flexible and convenient. Alternatively, the solder stamp inspection system may include a driven roller, with the traction roller, backlight roller, and driven roller arranged sequentially, in which case the backlight roller is used as a guide roller. Of course, without a driven roller, the backlight roller can also be used as a driven roller.

[0076] The light-emitting element 220 is at least partially disposed within the cylindrical body 240, including cases where the light-emitting element 220 is partially disposed within the cylindrical body 240 or where the light-emitting element 220 is completely disposed within the cylindrical body 240. The cylindrical body 240 is at least partially made of a light-transmitting material to allow the light from the light-emitting element 220 to illuminate the membrane region 110. The cylindrical body 240 may be made of transparent or translucent materials such as plastic or glass.

[0077] In this embodiment, the cylinder 240 can support the collector plate 100 by abutting against the back of the collector plate 100, and can also reduce the overall space occupied by the solder stamp detection system by having the light emitter 220 at least partially disposed inside the cylinder 240 (which can be understood as making the solder stamp detection system more compact), and reduce the risk of the light emitter 220 being damaged by external objects such as the welding device and transport vehicle.

[0078] In some embodiments, the light source 220 can be configured as a linear light source, with the light rays of the light source 220 parallel to the axis of the cylinder 240; the cylinder 240 is made of a light-diffusing material, for example, the cylinder 240 can be configured as a white light-diffusing plate made of polycarbonate, so that the light rays irradiated by the light source 220 onto the cylinder 240 can be transmitted outward evenly, thereby uniformly illuminating the above-mentioned film region 110 and the tab welding region 120.

[0079] In some embodiments, the solder stamp inspection system further includes a stroke sensor for detecting the rolling stroke of the cylinder 240. The stroke sensor can be configured as an angle encoder, which can be mounted on a rotating structure such as a shaft or motor corresponding to the cylinder 240. A host computer is used to cause the first camera 230 to acquire a first image based on the rolling stroke and a preset correspondence. It is understood that the first image capture range has a certain width, therefore continuous shooting by the first camera 230 is usually unnecessary. The first camera 230 can acquire the first image based on preset intervals along the rolling stroke; for example, the first camera 230 acquires the first image every time the rolling stroke reaches a preset distance value. The rolling stroke can be the rotation angle of the rotating structure such as the shaft or motor corresponding to the cylinder 240, the number of pulses given by the stroke sensor, etc.

[0080] In this embodiment, the host computer enables the first camera 230 to acquire the first image according to the rolling stroke and the preset correspondence, which can reduce the number of shots taken by the first image device and improve the automation level of the solder stamp detection system. Specifically, the automation level can be improved by setting the execution sequence in the host computer.

[0081] In some implementations, refer to Figure 5 and Figure 6 The collector plate 100 is used to move along the circumferential direction of the cylinder 240, for example, the collector plate 100 is used to move along the Y direction in the figure for conveying. The first camera 230 includes a line scan camera, the line scan lines of which are parallel to the axial direction of the cylinder 240. The line scan camera, also commonly referred to as a line array camera, performs line-by-line scanning, with each scan line (line scan line) being relatively long and narrow, forming an overall "line" shape. In this embodiment, as the collector plate 100 moves along the circumferential direction of the cylinder 240, the line scan lines of the line scan camera are parallel to the axial direction of the cylinder 240, thus enabling continuous imaging.

[0082] In this embodiment, since the solder mark structure 121 is usually formed on the side of the transport direction of the collector plate 100, the line scan line of the line scan camera is parallel to the axial direction of the cylinder 240, which is beneficial to improve the concentration of the line scan line and reduce the equipment cost of imaging.

[0083] In some implementations, refer to Figure 5 The solder stamp inspection system includes at least two first cameras 230, which are arranged along the axial direction of the cylinder 240, for example along... Figure 5 The current collectors are arranged along the X-axis. Along the transport direction of the current collector 100, there are tab welding areas 120 on both sides of the membrane region 110. Two first cameras 230 are used to acquire images of the tab welding areas 120 and the adjacent through holes, respectively.

[0084] For example, the first camera 230 includes at least two line scan cameras, which are arranged along the axial direction of the cylinder 240 and the line scan lines of the line scan cameras are parallel to the axial direction of the cylinder 240. Along the transport direction of the collector plate 100, the two sides of the membrane region 110 are respectively provided with tab welding regions 120, and the two line scan cameras are used to acquire images of the tab welding regions 120 and the adjacent through holes respectively.

[0085] In this embodiment, the first camera 230 is arranged along the axial direction of the cylinder 240, which is beneficial to improve the detection efficiency of the current collector 100 with electrode welding areas 120 on both sides. For example, the first cameras 230 on both sides detect the welding structure 121 of the electrode welding areas 120 on both sides of the membrane area 110.

[0086] In some implementations, refer to Figure 5 and Figure 6 The solder stamp inspection system also includes a second camera 250, which and the first camera 230 are spaced apart along the transport direction of the collector 100, for example, the second camera 250 and the first camera 230 are arranged along... Figure 6 The Y-axis or U-axis of the image is spaced apart. The second camera 250 is used to acquire a second image from the front of the current collector 100, and the second image includes at least an image of the film region 110. The host computer is used to enable the second camera 250 to acquire the second image based on the backlight roller illuminating the film region 110. It can be understood that the host computer enables the second camera 250 to acquire the second image under the condition that the backlight roller illuminating the film region 110. The second camera 250 can be set as a line scan camera or a CCD (Charge Coupled Device) camera, etc., and this embodiment does not limit it.

[0087] In this embodiment, the solder joint inspection system can acquire a second image via the second camera 250 to detect the forming quality of the film region 110 based on the second image, such as detecting whether there are wrinkles or splices. Since the current collector 100 is relatively fragile and may sometimes break, splices can be used to connect it, ensuring continuity of the current collector 100 at the break point. The image for detecting wrinkles can be referenced... Figure 9 or Figure 10 The detection images of the tape can be referenced. Figure 11 or Figure 12 .

[0088] Furthermore, the backlight roller can be used to acquire both the first and second images simultaneously. This can be understood as providing light to both the first camera 230 and the second camera 250 at the same time to help acquire the first and second images, thereby improving the utilization rate of the backlight roller and simplifying the solder stamping inspection system.

[0089] The cylinder 240 can be configured to include a first light-transmitting area and a second light-transmitting area arranged along its circumference. The first light-transmitting area is positioned opposite to the first camera 230, and the second light-transmitting area is positioned opposite to the second camera 250, thereby enabling the backlight roller to provide light to both the first camera 230 and the second camera 250. This can be understood as follows: during the rotation of the backlight roller and the cylinder 240, the rotation speed of the backlight roller and the cylinder 240 can be adjusted to match the shooting timing of the first camera 230 and the second camera 250, so that when the first camera 230 is shooting, the first light-transmitting area is positioned opposite to the first camera 230, and when the second camera 250 is shooting, the second light-transmitting area is positioned opposite to the second camera 250.

[0090] In this embodiment, the second camera 250 and the first camera 230 are spaced apart along the circumferential direction of the cylinder 240. This not only reduces mutual shooting interference by spacing them apart, but also covers the light-emitting surface of the backlight roller to a greater extent, further improving the utilization rate of the backlight roller and reducing the backlight roller's exposure to external light and interference.

[0091] In some implementations, refer to Figure 6 The first camera 230 can be positioned above the cylinder 240, and the second camera 250 can be positioned in front of the cylinder 240, so that the first camera 230 and the second camera 250 can cover the light-emitting surface of the backlight roller to a greater extent, thereby further reducing the backlight roller's illumination and interference to the outside world.

[0092] In some embodiments, the backlight roller is used to provide adjustable light intensity to the film area 110. For example, the backlight roller is configured as a light source with adjustable light intensity, or the internal light-emitting element 220 is configured as a light source with adjustable light intensity. In some embodiments, the light-transmitting structure provided on the cylinder 240 is used to provide adjustable light intensity to the film area 110. For example, the light-transmitting structure provided on the cylinder 240 is configured as a structure with adjustable opening and closing area, such as a louver.

[0093] In this embodiment, the backlight roller is used to provide adjustable light intensity to the film area 110, and the light-transmitting structure provided on the cylinder 240 is used to provide adjustable light intensity to the film area 110. These features help the soldering inspection system to adjust the contrast between the tab welding area 120 and the film area 110, thereby improving the adaptability of the soldering inspection system to the detection of current collectors 100 made of different materials.

[0094] In some implementations, refer to Figure 5The beam axis of the front light source 210 and the beam axis of the first camera 230 are at an angle, and the angle between the beam axis of the front light source 210 and the film surface of the current collector 100 is less than or equal to 45 degrees, thereby making the overall layout between the front light source 210 and the first camera 230 more compact and improving the compactness of the solder stamping detection system.

[0095] In some embodiments, the front light source 210 may include a first linear light source, the light rays of which are parallel to the cross-section of the cylinder 240 and parallel to the transport direction of the collector plate 100. In this case, the width of the light rays of the first linear light source can cover the tab welding area 120 and the portion of the film area 110 adjacent to the tab welding area 120 (the remaining portion of the film area 110 is not covered by the light rays of the first linear light source), so that the length of the light rays of the first linear light source is relatively long, thereby covering the shooting range of the first camera 230 (which may be a line scan camera) and forming redundancy in the length direction of the light rays, thereby improving the shooting quality through the length of the light rays and reducing the light energy consumption through the width of the light rays.

[0096] In some embodiments, the backlight roller includes a second linear light source, the light beam of which is parallel to the cross-section of the cylinder 240 and parallel to the transport direction of the collector plate 100. In this case, the width of the light beam of the second linear light source can cover the tab welding area 120 on the other side and the portion of the film area 110 adjacent to the tab welding area 120 (the remaining portion of the film area 110 is not covered by the light beam of the second linear light source). As a result, the length of the light beam of the second linear light source is relatively long, which can cover the shooting range of another first camera 230 (which can be a line scan camera) in the length direction of the light beam and form redundancy. Thus, the shooting quality is improved by the length of the light beam and the light energy consumption is reduced by the width of the light beam.

[0097] In some implementations, refer to Figure 5 The solder stamp inspection system also includes a mounting bracket 260, which can be an integral structure or comprise at least two spaced-apart bracket units. The first camera 230, the front light source 210, and the second camera 250 are movably connected to the mounting bracket 260 along the axial direction of the cylinder 240, for example, through structures such as slides or guide rails. This allows the first camera 230, the front light source 210, and the second camera 250 to adjust their working positions to illuminate or photograph different positions of the current collector 100, improving the flexibility of the solder stamp inspection system.

[0098] This application also proposes a solder mark detection method for detecting the aforementioned current collector 100; wherein, the solder mark detection method can be executed based on the aforementioned solder mark detection system, for example, at least some steps of the solder mark detection method can be executed by the aforementioned host computer.

[0099] Reference Figure 13 The solder stamp inspection method includes the following steps: In step S100, the tab welding area 120 is illuminated from the front of the current collector 100 so that the soldering structure 121 is illuminated and the tab welding area 120 outside the soldering structure 121 is darkened; specifically, the illumination can be performed by the aforementioned front light source 210.

[0100] In step S200, the film area 110 is irradiated from the back of the current collector 100, specifically by the backlight roller described above. Steps S100 and S200 can be executed sequentially before step S300 below, or steps S100 and S200 can be executed in parallel before step S300 below. This embodiment does not limit this.

[0101] Step S300: Obtain a first image from the front of the current collector 100. The first image includes at least an image of the solder structure 121 and an image of the through hole. Specifically, the first image can be obtained through the first camera 230.

[0102] The solder mark detection method in this application, when in use, can make the solder mark structure 121 bright and the solder mark area 120 outside the solder mark structure 121 dark by irradiating the electrode solder area 120 from the front of the current collector 100, and make the film area 110 bright by irradiating the film area 110 from the back of the current collector 100. This enhances the contrast between the solder mark area 120 outside the solder mark structure 121 and the film area 110 in the first image acquired by the first camera 230 from the front, thereby improving the detection success rate of the edge of the solder mark area 120.

[0103] Furthermore, by acquiring a first image while irradiating the tab welding area 120 and the film area 110, the first image can simultaneously contain an image of the tab welding area 120 and an image of the solder mark structure 121, reducing the overall number of images required and improving detection efficiency.

[0104] In some embodiments, the step of acquiring a first image from the front of the collector 100 (step S300 above) includes: The rolling stroke of the cylinder 240 is detected. The cylinder 240 is used to abut the back of the collector plate 100. For example, the rolling stroke of the cylinder 240 can be detected by the aforementioned stroke sensor. The first image is obtained based on the scroll stroke and a preset correspondence. For example, it can be set to obtain the first image every time the scroll stroke reaches a preset distance value.

[0105] In this embodiment, since the first image has a certain width, the first image is acquired according to the scroll stroke and the preset correspondence, which can reduce the number of times the first image device takes pictures and improve the automation level of the solder stamp detection method.

[0106] In some implementations, the solder stamp inspection method further includes the following steps: At least two first cameras 230 are provided, and the first cameras 230 are arranged along the axial direction of the cylinder 240. The cylinder 240 is used to abut the back of the collector plate 100. Along the transport direction of the collector plate 100, the two sides of the membrane region 110 are respectively provided with tab welding areas 120. The step of acquiring the first image from the front of the current collector 100 (step S300 above) includes: Images of the tab welding area 120 and the adjacent through hole are obtained respectively.

[0107] In this embodiment, the first camera 230 is arranged along the axial direction of the cylinder 240 to obtain images of the tab welding area 120 and the adjacent through hole, which is beneficial to improve the detection efficiency of the current collector 100 with tab welding areas 120 on both sides.

[0108] Reference Figure 14 In some implementations, the solder stamp inspection method may further include the following steps: Step S410: Based on the first image, obtain the first boundary line of the through hole, with the first boundary line facing the tab welding area 120; wherein, the first boundary line can be referenced Figure 8 Boundary line a in the middle; Step S420: Based on the first image, obtain the second boundary line of the solder joint structure 121, with the second boundary line facing the film region 110; wherein, the second boundary line can be referenced Figure 8 The boundary line b in the middle; wherein, steps S410 and S420 can be executed sequentially before step S430 below, or steps S410 and S420 can be executed in parallel before step S430 below, and this embodiment does not limit this. Step S430: Based on the first boundary line a, the second boundary line b, and the image parameters corresponding to the first image, obtain the distance from the solder structure 121 to the first boundary line a, for example, obtain... Figure 8 The distance between the middle boundary lines a and b.

[0109] In this embodiment, the solder stamp detection method can improve the detection efficiency of the distance between the solder stamp structure 121 and the first boundary line a by using the image parameters corresponding to the first boundary line a, the second boundary line b, and the first image, which is beneficial to detect possible distance anomalies in the solder stamp structure 121 as early as possible.

[0110] In some implementations, the image parameters corresponding to the first image include pixel precision; The step of obtaining the distance from the solder mark structure 121 to the first boundary line based on the first boundary line, the second boundary line, and the image parameters corresponding to the first image (step S430 above) includes: The distance from the solder pattern 121 to the first boundary line is obtained based on the pixel precision and the number of pixels between the first boundary line and the second boundary line; for example, the distance from the solder pattern 121 to the first boundary line is obtained by multiplying the number of pixels between the first boundary line and the second boundary line by the corresponding pixel precision.

[0111] In this embodiment, the distance from the solder mark structure 121 to the first boundary line is obtained based on the pixel accuracy and the number of pixels between the first boundary line and the second boundary line, which helps to improve the detection efficiency.

[0112] Reference Figure 14 In some implementations, the solder stamp inspection method further includes the following steps: Step S510: Based on the first image, obtain the second boundary line and the third boundary line of the solder joint structure 121. The second boundary line faces the film region 110, and the third boundary line faces away from the film region 110. The second boundary line can be referenced... Figure 8 Boundary line b in the middle, the third boundary line can be referred to Figure 8 The boundary line c in the diagram; it is understood that if it is necessary to obtain the first boundary line a, the second boundary line b, and the third boundary line c, the steps of obtaining the first boundary line a, obtaining the second boundary line b, and obtaining the third boundary line c can be performed sequentially or in parallel; in addition, the first boundary line a, the second boundary line b, and the third boundary line c can be obtained by image recognition based on pixel features such as pixel grayscale. Specifically, when the through holes are spaced apart, the first boundary line a can be fitted and formed by forming the envelope of the through holes; when the solder structures 121 are spaced apart, the second boundary line b and the third boundary line c can be fitted by forming the envelope of the solder structures 121. Step S520: Based on the second boundary line b, the third boundary line c, and the image parameters corresponding to the first image, obtain the distance between the second boundary line b and the third boundary line c, for example, obtain... Figure 8 The distance between the middle boundary lines b and c.

[0113] In this embodiment, the solder mark detection method can improve the detection efficiency of the overall width of the solder mark structure 121 by using the image parameters corresponding to the second boundary line b, the third boundary line c, and the first image, which is beneficial to detect possible abnormalities in the overall width of the solder mark structure 121 as early as possible.

[0114] In some implementations, the image parameters corresponding to the first image include pixel precision; The step of obtaining the distance between the second boundary line and the third boundary line based on the second boundary line, the third boundary line, and the image parameters corresponding to the first image (step S520 above) includes: The distance between the second boundary line b and the third boundary line c is obtained based on the pixel precision and the number of pixels between the second boundary line b and the third boundary line c; for example, the distance between the second boundary line b and the third boundary line c is obtained by multiplying the number of pixels between the second boundary line b and the third boundary line c by the corresponding pixel precision.

[0115] In this embodiment, the distance between the second boundary line b and the third boundary line c is obtained based on the pixel precision and the number of pixels between the second boundary line b and the third boundary line c, which helps to improve detection efficiency.

[0116] In some implementations, the solder stamp inspection method further includes the following steps: The number of solder mark structures 121 is obtained based on the first image and the first preset recognition model, wherein the first preset recognition model may be a preset correspondence or a preset recognition algorithm, etc.

[0117] In this embodiment, the solder mark detection method can improve the detection efficiency of the number of solder mark structures 121 by using a first image and a first preset recognition model.

[0118] In some embodiments, before the step of obtaining the number of solder mark structures 121 based on the first image and the first preset recognition model, the solder mark detection method further includes the following steps: At least one first training image is acquired from the front of the illuminated current collector 100. The first training image includes at least an image of the solder structure 121, which can be acquired, for example, by the first camera 230 described above. The solder structure 121 in the first training image is labeled with a number, for example, the solder structure 121 is labeled with a number from 1, 2, 3 to n, where n is a positive integer; Based on the first training image after quantitative labeling, a first preset recognition model is formed, for example, by training a recognition algorithm.

[0119] In this embodiment, the solder stamp detection method can form a more accurate first preset recognition model by using the first training image and the number of solder stamp structures 121, thereby improving the detection accuracy through the first preset recognition model.

[0120] Reference Figure 14 In some implementations, the solder stamp inspection method further includes the following steps: In step S610, based on the illumination of the membrane region 110, a second image is acquired from the front side of the current collector 100, the second image including at least an image of the membrane region 110; wherein, the second image can be acquired by the second camera 250 described above.

[0121] In this embodiment, the solder joint inspection method can detect the forming quality of the film region 110 by acquiring a second image, such as detecting whether there are wrinkles or splices. Since the current collector 100 is relatively fragile and may sometimes break, splices can be used to connect it, thus maintaining the continuity of the current collector 100 at the break point. The image for detecting wrinkles can be referenced... Figure 9 or Figure 10 The detection images of the tape can be referenced. Figure 11 or Figure 12 Furthermore, the solder mark detection method can simultaneously acquire a first image and a second image based on the irradiation of the film region 110, thereby improving detection efficiency.

[0122] Reference Figure 14 In some implementations, the solder stamp inspection method further includes the following steps: Step S620: Based on the second image and the second preset recognition model, obtain the wrinkles or joints in the second image, wherein the second preset recognition model may be a preset correspondence or a preset recognition algorithm, etc.

[0123] In this embodiment, the solder mark detection method can improve the detection efficiency of wrinkles or splices in the membrane region 110 by using a second image and a second preset recognition model.

[0124] In some embodiments, before the step of obtaining the wrinkles or joints in the second image based on the second image and the second preset recognition model, the solder stamp detection method further includes the following steps: At least one second training image is acquired from the illuminated front side, the second training image including at least an image of the membrane region 110, for example, by the second camera 250 described above; Label the folds or seams in the second training image; Based on the labeled second training image, a second preset recognition model is formed, for example, by training a recognition algorithm.

[0125] In this embodiment, the solder stamp detection method can form a more accurate second preset recognition model by using a second training image and annotating the wrinkles or joints in the second training image, thereby improving the detection accuracy through the second preset recognition model.

[0126] In this embodiment, the solder stamp detection method further includes the following steps: If the difference between the distance from the solder mark structure 121 to the first boundary line a and the first preset distance value is greater than or equal to the first preset difference, or if the difference between the distance between the second boundary line b and the third boundary line c of the solder mark structure 121 and the second preset distance value is greater than or equal to the second preset difference, then a prompt message will be output; the prompt message may be an alarm message, etc. The first preset difference and the second preset difference can be set to be less than or equal to 0.5 mm.

[0127] Correspondingly, the solder stamp detection system may include a corresponding prompting module, which may be included in the aforementioned host computer.

[0128] This application also proposes a method for manufacturing a current collector 100. The current collector manufacturing method includes the following steps: Prepare the above-mentioned current collector 100; For at least a portion of the current collectors 100 that have been prepared, the tab welding area 120 is irradiated from the front of the current collector 100 so that the solder pattern 121 is illuminated and the tab welding area 120 outside the solder pattern 121 is darkened; specifically, the irradiation can be performed by the aforementioned front light source 210. The film area 110 is irradiated from the back of the current collector 100, specifically through the aforementioned backlight roller; A first image is obtained from the front of the current collector, the first image including at least an image of the solder pattern 121 and an image of the through hole.

[0129] When the current collector production method of the present application is used, it can make the tab welding area 120 bright and the tab welding area 120 outside the tab welding area dark by irradiating the tab welding area 120 from the front of the current collector 100, and make the film area 110 bright by irradiating the film area 110 from the back of the current collector 100. This enhances the contrast between the tab welding area 120 outside the tab welding area 121 and the film area 110 in the first image acquired by the first camera 230 from the front, thereby improving the detection success rate of the edge of the tab welding area 120.

[0130] Furthermore, by acquiring a first image while irradiating the tab welding area 120 and the film area 110, the first image can simultaneously contain an image of the tab welding area 120 and an image of the solder mark structure 121, reducing the number of shots and improving detection efficiency.

[0131] In some embodiments, the step of fabricating the current collector 100 includes: Multiple arrays of through holes are formed; for example, multiple arrays of through holes that penetrate the thickness of the current collector layer can be formed first, for example, through laser processing or other means; then an active material layer is formed on the current collector layer to form electrode segments, and the through holes are kept conductive to form through holes.

[0132] Multiple solder patterns 121 are formed, and the arrangement direction of the solder patterns 121 is parallel to the arrangement direction of the through holes; for example, adapter plates can be connected on electrode segments and multiple solder patterns 121 are formed during connection (e.g., the adapter plates are connected by ultrasonic roll welding), and the arrangement direction of the solder patterns 121 is parallel to the arrangement direction of the through holes, and the adapter plates cover the active material layer or the edge of the adapter plates abuts against the edge of the active material layer; wherein, the film region 110 includes the area where the active material layer extends out of the adapter plate, and the tab welding region 120 includes the area where the adapter plate is located.

[0133] In this embodiment, the current collector manufacturing method can improve the detection efficiency of detecting the distance of the solder pattern 121 by making the arrangement direction of the solder pattern 121 parallel to the arrangement direction of the through hole, so that the through hole can be used as a positioning reference for the solder pattern 121.

[0134] In some embodiments, the step of fabricating the current collector 100 includes: At least two electrode segments are stacked, and the through holes of the electrode segments on different layers are connected. This can be understood as the current collector 100 being two or more stacked positive or negative electrode films, for example, two or more positive or negative electrode films are stacked together for testing. This improves the overall testing efficiency of the electrode segments.

[0135] In some embodiments, the step of fabricating the current collector 100 includes: The current collector layer is formed from copper foil or a composite foil containing a copper layer; and / or, the tab soldering area 120 and the film area 110 are connected; and / or, the ratio of the aperture of the through hole on the current collector layer to the diameter of the envelope circle of the solder pattern 121 is less than or equal to 0.1, including less than or equal to 0.05 or 0.01; and / or, projecting along the thickness direction of the electrode segment, the ratio of the aperture of the through hole on the stacked electrode segment to the diameter of the envelope circle of the solder pattern 121 is less than or equal to 0.1, including less than or equal to 0.05 or 0.01. In this case, the overall weight of the current collector 100 can be reduced by using the through holes on the current collector layer while simultaneously detecting the solder pattern 121.

[0136] Reference Figures 5 to 12This application proposes a solder stamp inspection system for inspecting a current collector 100. The current collector 100 includes a film region 110 and a tab welding region 120 arranged along the film surface of the current collector 100. The film region 110 has a through hole penetrating the thickness of the current collector 100, and the tab welding region 120 has a solder stamp structure 121. The solder stamp inspection system includes a front light source 210, a backlight roller, a first camera 230, and a host computer. The front light source 210 is used to irradiate the tab welding region 120 from the front of the current collector 100. 20, so that the soldering structure 121 is illuminated and the tab welding area 120 outside the soldering structure 121 is darkened; the backlight roller is used to irradiate the film area 110 from the back of the current collector 100, the back and front are arranged opposite each other; the first camera 230 is used to acquire a first image from the front of the current collector 100, the first image including at least an image of the soldering structure 121 and an image of the through hole; the host computer is used to enable the first camera 230 to acquire the first image based on the front light source 210 irradiating the tab welding area 120 and the backlight roller irradiating the film area 110. The backlight roller includes a cylinder 240 and a light emitter 220, the cylinder 240 is used to abut the back of the current collector 100; the light emitter 220 is at least partially disposed inside the cylinder 240, the cylinder 240 is at least partially made of a light-transmitting material so that the light from the light emitter 220 irradiates the film area 110. The solder stamp detection system also includes a traction roller, which supports the collector plate 100 and pulls it forward; the light source 220 is configured as a linear light source, and the light rays of the light source 220 are parallel to the axis of the cylinder 240, which is made of a light-diffusing material. The solder stamp detection system also includes a stroke sensor, which detects the rolling stroke of the cylinder 240; the host computer is used to enable the first camera 230 to acquire a first image based on the rolling stroke and a preset correspondence. The collector plate 100 is used to move along the circumferential direction of the cylinder 240, and the first camera 230 includes a line scan camera, the line scan of which is parallel to the axial direction of the cylinder 240. The solder stamp detection system includes at least two first cameras 230, which are arranged along the axial direction of the cylinder 240; along the transport direction of the collector plate 100, electrode welding areas 120 are respectively provided on both sides of the membrane area 110, and the two first cameras 230 are used to acquire images of the electrode welding areas 120 and adjacent through holes, respectively. The solder stamp inspection system also includes a second camera 250, and the second camera 250 and the first camera 230 are spaced apart along the transport direction of the collector sheet 100; the second camera 250 is used to acquire a second image from the front, and the second image includes at least an image of the film area 110; the host computer is used to enable the second camera 250 to acquire the second image based on the backlight roller illuminating the film area 110.The collector plate 100 is used for transporting along the circumferential direction of the cylinder 240. The second camera 250 and the first camera 230 are spaced apart along the circumferential direction of the cylinder 240. The cylinder 240 includes a first light-transmitting area and a second light-transmitting area arranged along the circumferential direction of the cylinder 240. The first light-transmitting area is arranged opposite to the first camera 230, and the second light-transmitting area is arranged opposite to the second camera 250. The backlight roller or light emitter 220 is used to provide adjustable light intensity to the film area 110, and / or the light-transmitting structure provided on the cylinder 240 is used to provide adjustable light intensity to the film area 110. The first camera 230 includes at least two line scan cameras, which are arranged along the axial direction of the cylinder 240, and the line scan lines of the line scan cameras are parallel to the axial direction of the cylinder 240. Along the transport direction of the collector plate 100, tab welding areas 120 are respectively provided on both sides of the film area 110. The two line scan cameras are used to acquire images of the tab welding areas 120 and adjacent through holes, respectively. The first camera 230 is positioned above the cylinder 240, and the second camera 250 is positioned in front of the cylinder 240. The beam axis of the front light source 210 forms an angle with the beam axis of the first camera 230, and the angle between the beam axis of the first beam and the film surface of the current collector 100 is less than or equal to 45 degrees. The front light source 210 includes a first linear light source, the ray beams of which are parallel to the cross-section of the cylinder 240 and the transport direction of the current collector 100. The backlight roller includes a second linear light source, the ray beams of which are parallel to the cross-section of the cylinder 240 and the transport direction of the current collector 100. The solder joint detection system also includes a mounting bracket 260, and the first camera 230, the front light source 210, and the second camera 250 are movably connected to the mounting bracket 260 along the axial direction of the cylinder 240.

[0137] Reference Figure 14 This application proposes a solder mark detection method for detecting current collectors 100. The current collector 100 includes a film region 110 and a tab welding region 120 arranged along the film surface of the current collector 100. The film region 110 has a through hole penetrating the thickness of the current collector 100, and the tab welding region 120 has a solder mark structure 121. The solder mark detection method includes the following steps: The tab welding area 120 is illuminated from the front of the current collector 100, so that the solder pattern 121 is bright and the tab welding area 120 outside the solder pattern 121 is dark. The film area 110 is irradiated from the back side of the current collector 100, with the back side and the front side facing each other; A first image is obtained from the front of the current collector 100. The first image includes at least an image of the solder pattern 121 and an image of the through hole.

[0138] The step of acquiring the first image from the front of the collector 100 includes: The rolling stroke of the detection cylinder 240 is used to abut the back of the collector plate 100; The first image is obtained based on the scrolling stroke and the preset correspondence.

[0139] The solder stamp inspection method also includes the following steps: At least two first cameras 230 are provided, and the first cameras 230 are arranged along the axial direction of the cylinder 240. The cylinder 240 is used to abut against the back of the collector plate 100. Along the transport direction of the collector plate 100, the two sides of the membrane region 110 are respectively provided with tab welding areas 120. The step of acquiring a first image from the front of the collector 100 includes: Images of the tab welding area 120 and the adjacent through hole are obtained respectively.

[0140] The solder stamp inspection method also includes the following steps: Based on the first image, the first boundary line of the through hole is obtained, and the first boundary line is directed toward the tab welding area 120; Based on the first image, the second boundary line of the solder structure 121 is obtained, and the second boundary line faces the membrane region 110. Based on the first boundary line, the second boundary line, and the image parameters corresponding to the first image, the distance from the solder mark structure 121 to the first boundary line is obtained.

[0141] The image parameters corresponding to the first image include pixel precision; The step of obtaining the distance from the solder mark structure 121 to the first boundary line based on the first boundary line, the second boundary line, and the image parameters corresponding to the first image includes: The distance from the solder pattern 121 to the first boundary line is obtained based on the pixel precision and the number of pixels between the first boundary line and the second boundary line.

[0142] The solder stamp inspection method also includes the following steps: Based on the first image, the second boundary line and the third boundary line of the solder structure 121 are obtained. The second boundary line faces the membrane region 110 and the third boundary line faces away from the membrane region 110. The distance between the second boundary line and the third boundary line is obtained based on the image parameters corresponding to the second boundary line, the third boundary line, and the first image.

[0143] The image parameters corresponding to the first image include pixel precision; The step of obtaining the distance between the second boundary line and the third boundary line based on the second boundary line, the third boundary line, and the image parameters corresponding to the first image includes: The distance between the second and third boundary lines is obtained based on the pixel precision and the number of pixels between the second and third boundary lines.

[0144] The solder stamp inspection method also includes the following steps: The number of solder marks 121 is obtained based on the first image and the first preset recognition model.

[0145] Prior to the step of obtaining the number of solder mark structures 121 based on the first image and the first preset recognition model, the solder mark detection method further includes the following steps: At least one first training image is obtained from the illuminated front side, the first training image including at least an image of the solder structure 121; The number of solder joint structures 121 in the first training image is labeled; Based on the first training image after quantitative labeling, a first preset recognition model is formed.

[0146] The solder stamp inspection method also includes the following steps: A second image is acquired from the front side of the current collector 100 based on the irradiation of the membrane region 110. The second image includes at least an image of the membrane region 110.

[0147] The solder stamp inspection method also includes the following steps: Based on the second image and the second preset recognition model, obtain the folds or seams in the second image.

[0148] Prior to the step of obtaining the wrinkles or joints in the second image based on the second image and the second preset recognition model, the solder stamp detection method further includes the following steps: At least one second training image is acquired from the front of the irradiated current collector 100, the second training image including at least an image of the membrane region 110; Label the folds or seams in the second training image; A second preset recognition model is formed based on the labeled second training image.

[0149] This application proposes a method for manufacturing current collectors, which includes the following steps: A current collector 100 is prepared. The current collector 100 includes a membrane region 110 and an electrode welding region 120 arranged along the membrane surface of the current collector 100. The membrane region 110 is provided with a through hole that penetrates the thickness of the current collector 100, and the electrode welding region 120 is provided with a solder mark structure 121. For at least a portion of the current collectors 100 prepared, the tab welding area 120 is irradiated from the front of the current collector 100 so that the solder pattern 121 is illuminated and the tab welding area 120 outside the solder pattern 121 is darkened. The film area 110 is irradiated from the back side of the current collector 100, with the back side and the front side facing each other; A first image is obtained from the front of the current collector 100. The first image includes at least an image of the solder pattern 121 and an image of the through hole.

[0150] The steps for preparing the current collector 100 include: Multiple arrays are formed with through holes that penetrate the thickness of the current collector 100; Multiple solder patterns 121 are formed, and the arrangement direction of the solder patterns 121 is parallel to the arrangement direction of the through holes.

[0151] The steps for preparing the current collector 100 include: Multiple arrays of through-holes are formed on the current collector layer, extending through the thickness of the current collector layer; An active material layer is set on the current collector layer to form electrode segments, and the through holes are kept open to form through holes; Connect the adapter sheet to the electrode segment and form multiple solder patterns 121 during connection. The arrangement direction of the solder patterns 121 is parallel to the arrangement direction of the through holes, and the adapter sheet covers the active material layer or the edge of the adapter sheet abuts the edge of the active material layer. The film region 110 includes the area where the active material layer extends out of the adapter sheet, and the tab welding region 120 includes the area where the adapter sheet is located.

[0152] The steps for preparing the current collector 100 include: Stack at least two electrode segments and connect the through holes of the electrode segments on different stacks.

[0153] The steps for preparing the current collector 100 include: The current collector layer is formed by copper foil or by a composite foil containing a copper layer; And / or, to connect the tab welding area 120 and the membrane area 110; And / or, the ratio of the aperture of the through hole on the current collector layer to the diameter of the envelope circle of the solder pattern 121 is less than or equal to 0.1; And / or, projecting along the thickness direction of the electrode segment, the ratio of the diameter of the through hole on the stacked electrode segment to the diameter of the envelope circle of the solder pattern 121 is less than or equal to 0.1.

[0154] It is understood that the specific structure of the solder stamp inspection method and the current collector production method refers to the above-described embodiment of the solder stamp inspection system. Since the solder stamp inspection method and the current collector production method adopt all the technical solutions of all the above embodiments, they have at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated here.

[0155] The above description is merely a preferred embodiment of this application and does not limit the patent scope of this application. Any equivalent structural transformations made based on the technical concept of this application and the contents of the specification and drawings of this application, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this application.

Claims

1. A solder stamp inspection system, characterized in that, The solder mark inspection system is used to inspect the current collector of a lithium battery. The current collector includes a film region and a tab welding region. The film region has multiple through holes, and the tab welding region has a solder mark structure. The solder mark inspection system includes: A front light source is used to illuminate the tab welding area from the front of the current collector, so that the soldering structure is illuminated and the tab welding area outside the soldering structure is darkened. A backlight roller, which supports the back side of the current collector and illuminates the film area from the back side of the current collector; A first camera is used to acquire a first image from the front of the current collector, the first image including at least an image of the solder pattern and an image of the through hole; A host computer is configured to enable the first camera to acquire the first image based on the front light source illuminating the tab welding area and the backlight roller illuminating the film area.

2. The solder mark detection system as described in claim 1, characterized in that, The backlight roller includes a cylindrical body and a light-emitting element. The light-emitting element is at least partially disposed within the cylindrical body, and the cylindrical body is used to abut against the back of the current collector. The cylindrical body is at least partially made of a light-transmitting material so that the light from the light-emitting element can irradiate the membrane area.

3. The solder mark detection system as described in claim 2, characterized in that, The solder mark detection system further includes a traction roller, which supports the collector plate and pulls the collector plate forward; and / or, the light source is configured as a linear light source, the light rays of the light source are parallel to the axis of the cylinder, and the cylinder is made of a light-diffusing material.

4. The solder mark detection system as described in claim 2, characterized in that, The solder mark detection system also includes a stroke sensor, which is used to detect the rolling stroke of the cylinder; the host computer is used to enable the first camera to acquire the first image according to the rolling stroke and a preset correspondence.

5. The solder mark detection system as described in claim 2, characterized in that, The collector plate is used to move along the circumferential direction of the cylinder, and the first camera includes a line scan camera, the line scan line of the line scan camera being parallel to the axial direction of the cylinder.

6. The solder mark detection system as described in any one of claims 2 to 5, characterized in that, The solder stamp detection system includes at least two first cameras, which are arranged along the axial direction of the cylinder. Along the transport direction of the current collector, the tab welding area is provided on both sides of the membrane region, and the two first cameras are used to acquire images of the tab welding area and the adjacent through hole, respectively.

7. The solder mark detection system as described in any one of claims 2 to 5, characterized in that, The solder stamp inspection system also includes a second camera, which is spaced apart from the first camera along the transport direction of the collector plate; The second camera is used to acquire a second image from the front of the current collector, the second image including at least an image of the membrane region; The host computer is used to enable the second camera to acquire the second image based on the backlight roller illuminating the film area.

8. The solder mark detection system as described in claim 7, characterized in that, The collector plate is used for transporting along the circumferential direction of the cylinder, and the second camera and the first camera are spaced apart along the circumferential direction of the cylinder; The cylinder includes a first light-transmitting area and a second light-transmitting area arranged along the circumferential direction of the cylinder. The first light-transmitting area is arranged opposite to the first camera, and the second light-transmitting area is arranged opposite to the second camera.

9. A method for detecting solder marks, characterized in that, The solder mark detection method is used to inspect the current collector of a lithium battery. The current collector includes a film region and a tab welding region. The film region has multiple through holes, and the tab welding region has a solder mark structure. The solder mark detection method includes the following steps: The electrode welding area is illuminated from the front of the current collector so that the solder pattern is illuminated and the electrode welding area outside the solder pattern is darkened. The membrane region is illuminated from the back of the current collector; A first image is obtained from the front of the current collector, the first image including at least an image of the solder pattern and an image of the through hole.

10. The solder mark detection method as described in claim 9, characterized in that, The step of acquiring a first image from the front of the current collector includes: The rolling stroke of the detection cylinder is used to abut against the back side of the collector plate; The first image is obtained based on the scrolling stroke and the preset correspondence.

11. The solder mark detection method as described in claim 9, characterized in that, The solder stamp detection method further includes the following steps: At least two first cameras are provided, arranged along the axial direction of the cylinder, which is used to abut the back of the current collector; along the transport direction of the current collector, the electrode tab welding area is provided on both sides of the membrane region; The step of acquiring a first image from the front of the current collector includes: Images of the electrode welding area and the adjacent through hole are acquired respectively.

12. The solder mark detection method according to any one of claims 9 to 11, characterized in that, The solder stamp detection method further includes the following steps: Based on the first image, obtain the first boundary line of the through hole, with the first boundary line facing the electrode welding area; Based on the first image, obtain the second boundary line of the solder mark structure, the second boundary line facing the film region; The distance from the solder mark structure to the first boundary line is obtained based on the image parameters corresponding to the first boundary line, the second boundary line, and the first image.

13. The solder mark detection method as described in claim 12, characterized in that, The image parameters corresponding to the first image include pixel precision; The step of obtaining the distance from the solder mark structure to the first boundary line based on the first boundary line, the second boundary line, and the image parameters corresponding to the first image includes: The distance from the solder pattern to the first boundary line is obtained based on the pixel precision and the number of pixels between the first boundary line and the second boundary line.

14. The solder mark detection method according to any one of claims 9 to 11, characterized in that, The solder stamp detection method further includes the following steps: Based on the first image, a second boundary line and a third boundary line of the solder pattern are obtained, wherein the second boundary line faces the film region and the third boundary line faces away from the film region. The distance between the second boundary line and the third boundary line is obtained based on the image parameters corresponding to the second boundary line, the third boundary line, and the first image.

15. The solder mark detection method as described in claim 14, characterized in that, The image parameters corresponding to the first image include pixel precision; The step of obtaining the distance between the second boundary line and the third boundary line based on the second boundary line, the third boundary line, and the image parameters corresponding to the first image includes: The distance between the second boundary line and the third boundary line is obtained based on the pixel precision and the number of pixels between the second boundary line and the third boundary line.

16. The solder mark detection method according to any one of claims 9 to 11, characterized in that, The solder stamp detection method further includes the following steps: The number of the solder marks is obtained based on the first image and the first preset recognition model.

17. The solder mark detection method as described in claim 16, characterized in that, Before the step of obtaining the number of solder marks based on the first image and the first preset recognition model, the solder mark detection method further includes the following steps: At least one first training image is obtained from the front of the current collector being illuminated, the first training image including at least an image of the solder pattern; The number of solder marks in the first training image is labeled. The first preset recognition model is formed based on the first training image after numerical labeling.

18. The solder mark detection method according to any one of claims 9 to 11, characterized in that, The solder stamp detection method further includes the following steps: A second image is acquired from the front of the current collector based on the irradiation of the membrane region, the second image including at least an image of the membrane region.

19. The solder mark detection method as described in claim 18, characterized in that, The solder stamp detection method further includes the following steps: Based on the second image and the second preset recognition model, obtain the folds or seams in the second image.

20. A method for producing current collector chips, characterized in that, The current collector manufacturing method includes the following steps: A current collector for preparing a lithium battery is provided, the current collector comprising a film region and a tab welding region, the film region having multiple through holes and the tab welding region having a solder mark structure; For at least a portion of the current collectors prepared, the tab welding area is illuminated from the front of the current collectors so that the solder pattern is illuminated and the tab welding area outside the solder pattern is darkened. The membrane region is illuminated from the back of the current collector; A first image is obtained from the front of the current collector, the first image including at least an image of the solder pattern and an image of the through hole.

21. The method for producing current collectors as described in claim 20, characterized in that, The steps for preparing current collectors for lithium batteries include: The through holes are arranged in a plurality of arrays; Multiple solder patterns are formed, and the arrangement direction of the solder patterns is parallel to the arrangement direction of the through holes.

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