Weld mark inspection system, weld mark inspection method, and current collector production method

Abstract

A weld mark inspection system, a weld mark inspection method, and a current collector (100) production method. The weld mark inspection system comprises a front light source (210), a backlight roller, a first camera (230), and an upper-level computer. The front light source (210) is configured to irradiate a tab welding region (120) from a front side of the current collector (100), so that a weld mark structure (121) appears bright and portions of the tab welding region (120) other than the weld mark structure (121) appear dark. The backlight roller is configured to irradiate a film region (110) from a rear side of the current collector (100), the rear side being disposed opposite to the front side. The first camera (230) is configured to acquire a first image from the front side, the first image at least comprising an image of the weld mark structure (121) and an image of a through-hole. The upper-level computer is configured to enable the first camera (230) to acquire the first image on the basis of the front light source (210) irradiating the tab welding region (120) and the backlight roller irradiating the film region (110), thereby enhancing the contrast between the portions of the tab welding region (120) other than the weld mark structure (121) and the film region (110) in the first image, and improving the inspection success rate of edges of the tab welding region (120).

Description

Solder print detection system, solder print detection method and tab production method

[0001] The present application claims priority to the Chinese patent application No. 202411066797.5, filed on August 5, 2024, and entitled "Solder print detection system, solder print detection method and tab production method", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the technical field of battery cell manufacturing, in particular to a solder print detection system, a solder print detection method and a tab production method. BACKGROUND

[0003] A lithium ion battery cell generally includes a positive tab, a negative tab and a separator between the two, wherein the positive tab generally 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, and the negative tab generally 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, wherein the positive active material includes lithium nickel manganese cobalt oxide and lithium nickel cobalt aluminum oxide, and the negative active material includes graphite or carbon with a graphite-like structure.

[0004] After the positive tab and the negative tab are formed by coating the active material and rolling, some technologies use ultrasonic roll welding to connect the adapter tabs to form the tabs, which forms a solder print structure. In related technologies, one side of the solder print structure is a recess close to a rectangle, and the other side of the solder print structure is a protrusion close to an ellipse.

[0005] In related technologies, visual detection is usually used to detect the distance of the solder print structure to the active material layer, the overall width of the solder print structure or the number of solder print structures. However, sometimes it is difficult to determine the edge of the solder print structure, and the detection success rate needs to be improved. TECHNICAL SOLUTION

[0006] The main purpose of the present application is to provide a solder print detection system to improve the detection success rate.

[0007] To achieve the above object, the welding mark detection system for detecting the current collector of the lithium battery is provided, the current collector comprises a film area and a tab welding area, the film area is provided with a plurality of through holes, and the tab welding area is provided with a welding mark structure, and the welding mark detection system comprises a front light source, a back light roller, a first camera and an upper computer, the front light source is used for irradiating the tab welding area from the front of the current collector, so that the welding mark structure is bright and the tab welding area outside the welding mark structure is dark, the back light roller is used for supporting the back of the current collector and irradiating the film area from the back of the current collector, the first camera is used for acquiring a first image from the front of the current collector, and the first image at least comprises an image of the welding mark structure and an image of the through hole, and the upper computer is used for enabling the first camera to acquire the first image based on the front light source irradiating the tab welding area and the back light roller irradiating the film area.

[0008] The related art generally sets a light source and a camera on the front of the current collector, brightens the welding mark structure and darkens the adapter sheet outside the welding mark structure through the light source, and forms a bright area by forming a gap between the welding mark structure on the current collecting layer and the active material layer, so as to perform image visual detection on the welding mark structure. However, part of the active material area of the current collector is changed from a whole solid structure that is not transparent to a through hole in the form of a mesh hole (for example, the negative current collecting layer adopts a copper foil with multiple micropores), and the adapter sheet covers the active material layer, at this time, most of the light passes through the through hole and is not reflected back to the camera, resulting in that the adapter sheet and the film area where the active material layer is located are both dark, so that the image contrast is insufficient, the boundary between the adapter sheet and the active material layer is dark, and it is difficult to judge the edge condition of the welding mark structure; since the through hole in the form of a micropore on the current collecting layer and a mesh hole on the active material area is relatively small, it is generally difficult to find that the light passes through and is not reflected back to the camera.

[0009] In use, the welding mark detection system in the technical scheme of the present application brightens the welding mark structure and darkens the tab welding area outside the welding mark structure by enabling the front light source to irradiate the tab welding area from the front of the current collector, and brightens the film area by enabling the back light roller to irradiate the film area from the back of the current collector, so that the contrast between the tab welding area outside the welding mark structure and the film area in the first image acquired from the front by the first camera is enhanced, and the detection success rate of the edge of the tab welding area is improved.

[0010] In addition, the upper computer enables the first camera to acquire the first image based on the front light source irradiating the tab welding area and the back light roller irradiating the film area, so that the first image can simultaneously contain the image of the tab welding area and the image of the welding mark structure, the number of shooting times required as a whole is reduced, and the detection efficiency is improved.

[0011] Optionally, the backlight roller comprises a barrel and a light emitter, the light emitter is at least partially arranged in the barrel, the barrel is used to abut the back surface of the current collector sheet; the barrel is at least partially made of light-transmitting material, so that the light of the light emitter irradiates the film area.

[0012] At this time, the barrel can not only support the current collector sheet by abutting the back surface of the current collector sheet, but also reduce the overall space occupation of the welding mark detection system and reduce the risk of damage to the light emitter by external objects by arranging the light emitter at least partially in the barrel.

[0013] Optionally, the welding mark detection system further comprises a traction roller, the traction roller is used to support the current collector sheet and pull the current collector sheet forward; and / or the light emitter is arranged as a linear light source, the light of the light emitter is parallel to the axial line of the barrel, and the barrel is made of a light-uniform material.

[0014] At this time, the current collector sheet can be provided with a forward moving force by the traction roller, which reduces the power output requirement of the backlight roller to the current collector sheet, reduces the friction requirement between the barrel and the current collector sheet, and makes the preparation of the barrel more flexible and convenient. The barrel is made of a light-uniform material, so that the light irradiated by the light emitter to the barrel can be uniformly transmitted outward, thereby uniformly illuminating the above-mentioned film area and the tab welding area.

[0015] Optionally, the welding mark detection system further comprises a stroke sensor, the stroke sensor is used to detect the rolling stroke of the barrel; and the upper computer is used to make the first camera acquire the first image according to the rolling stroke and a preset corresponding relationship.

[0016] At this time, since the shooting range of the first image device has a certain width, the upper computer makes the first camera acquire the first image according to the rolling stroke and the preset corresponding relationship, which can reduce the shooting times of the first image device and improve the automation degree of the welding mark detection system.

[0017] Optionally, the current collector sheet is used to move along the circumferential direction of the barrel, and the first camera comprises a line-scan camera, and the line-scan line of the line-scan camera is parallel to the axial direction of the barrel.

[0018] At this time, since the welding mark structure is usually formed on the side of the transportation direction of the current collector sheet, the line-scan line of the line-scan camera is parallel to the axial direction of the barrel, which is beneficial to improve the concentration degree of the line-scan line and reduce the equipment cost of imaging.

[0019] Optionally, the welding mark detection system comprises at least two first cameras arranged along the axial direction of the cylinder body; along the conveying direction of the current collector, both sides of the film area are respectively provided with the tab welding area, and the two first cameras are used to respectively acquire images of the tab welding area and the adjacent through hole.

[0020] At this time, the first camera is arranged along the axial direction of the cylinder body, which is conducive to improving the detection efficiency of the current collector provided with the tab welding area on both sides.

[0021] Optionally, the welding mark detection system further comprises a second camera, the second camera and the first camera are arranged at intervals along the conveying direction of the current collector; the second camera is used to acquire a second image from the front of the current collector, and the second image at least comprises an image of the film area; and the upper computer is used to make the second camera acquire the second image based on the backlight roller irradiating the film area.

[0022] At this time, the welding mark detection system can acquire the second image through the second camera, so as to detect the forming quality of the film area according to the second image; in addition, the backlight roller can be used to acquire the first image and the second image at the same time, thereby improving the utilization rate of the backlight roller and the degree of simplification of the welding mark detection system.

[0023] Optionally, the current collector is used to convey along the circumferential direction of the cylinder body, and the second camera and the first camera are arranged at intervals along the circumferential direction of the cylinder body; the cylinder body comprises a first light transmission area and a second light transmission area arranged along the circumferential direction of the cylinder body, the first light transmission area is used to be arranged opposite to the first camera, and the second light transmission area is used to be arranged opposite to the second camera.

[0024] At this time, the second camera and the first camera are arranged at intervals along the circumferential direction of the cylinder body, which can not only reduce the shooting interference between each other by being arranged at intervals, but also can cover the light-emitting surface of the backlight roller to a greater extent, thereby further improving the utilization rate of the backlight roller and reducing the irradiation and interference of the backlight roller to the outside world.

[0025] The application further provides a welding mark detection method for detecting a current collector of a lithium battery, the current collector comprising a film area and a tab welding area, the film area being provided with a plurality of through holes, and the tab welding area being provided with a welding mark structure, the welding mark detection method comprising the following steps:

[0026] Irradiating the tab welding area from the front of the current collector, so that the welding mark structure is bright and the tab welding area outside the welding mark structure is dark;

[0027] Irradiating the film area from the back of the current collector;

[0028] acquire a first image from the front of the current collector tab, the first image comprising at least an image of the weld structure and an image of the through hole.

[0029] The weld detection method in the technical solution of the present application can make the weld structure bright and the tab welding area outside the weld structure dark by irradiating the tab welding area from the front of the current collector tab, and make the film area bright by irradiating the film area from the back of the current collector tab, so that the contrast between the tab welding area outside the weld structure and the film area in the first image acquired from the front by the first camera is enhanced, and the detection success rate of the edge of the tab welding area is improved.

[0030] In addition, the first image is acquired by irradiating the tab welding area and the film area, so that the first image can contain the image of the tab welding area and the image of the weld structure at the same time, the number of shooting times is reduced, and the detection efficiency is improved.

[0031] Optionally, the step of acquiring the first image from the front of the current collector tab comprises:

[0032] detect the rolling stroke of a cylinder body, the cylinder body being used to abut against the back of the current collector tab;

[0033] acquire the first image according to the rolling stroke and a preset corresponding relationship.

[0034] At this time, since the first image has a certain width, acquiring the first image according to the rolling stroke and the preset corresponding relationship can reduce the number of shooting times of the first image device and improve the automation degree of the weld detection method.

[0035] Optionally, the weld detection method further comprises the following steps:

[0036] at least two first cameras are arranged along the axial direction of the cylinder body, the cylinder body being used to abut against the back of the current collector tab; and the tab welding area is arranged on both sides of the film area along the transportation direction of the current collector tab;

[0037] The step of acquiring the first image from the front of the current collector tab comprises:

[0038] images of the tab welding area and the adjacent through hole are acquired respectively.

[0039] At this time, based on the arrangement of the first cameras along the axial direction of the cylinder body, images of the tab welding area and the adjacent through hole are acquired respectively, which is beneficial to improving the detection efficiency of the current collector tab with the tab welding area arranged on both sides.

[0040] Optionally, the weld detection method further comprises the following steps:

[0041] According to the first image, a first boundary line of the through-hole is obtained, the first boundary line is towards the tab welding area;

[0042] According to the first image, a second boundary line of the welding mark structure is obtained, the second boundary line is towards the film area;

[0043] According to the first boundary line, the second boundary line and the image parameters corresponding to the first image, the distance from the welding mark structure to the first boundary line is obtained.

[0044] At this time, the welding mark detection method can improve the detection efficiency of detecting the distance from the welding mark structure to the first boundary line through the first boundary line, the second boundary line and the image parameters corresponding to the first image, which is beneficial to find the distance abnormal situation of the welding mark structure as soon as possible.

[0045] Optionally, the image parameters corresponding to the first image include pixel accuracy;

[0046] According to the first boundary line, the second boundary line and the image parameters corresponding to the first image, the step of obtaining the distance from the welding mark structure to the first boundary line includes:

[0047] According to the pixel accuracy, the number of pixels between the first boundary line and the second boundary line, the distance from the welding mark structure to the first boundary line is obtained.

[0048] At this time, according to the pixel accuracy and the number of pixels between the first boundary line and the second boundary line, the distance from the welding mark structure to the first boundary line is obtained, which is beneficial to improve the detection efficiency.

[0049] Optionally, the welding mark detection method further includes the following steps:

[0050] According to the first image, a second boundary line and a third boundary line of the welding mark structure are obtained, the second boundary line is towards the film area, and the third boundary line is away from the film area;

[0051] According to the second boundary line, the third boundary line and the image parameters corresponding to the first image, the distance between the second boundary line and the third boundary line is obtained.

[0052] At this time, the welding mark detection method can improve the detection efficiency of detecting the overall width of the welding mark structure through the second boundary line, the third boundary line and the image parameters corresponding to the first image, which is beneficial to find the overall width abnormal situation of the welding mark structure as soon as possible.

[0053] Optionally, the image parameters corresponding to the first image include pixel accuracy;

[0054] According to the second boundary line, the third boundary line and the image parameters corresponding to the first image, the distance between the second boundary line and the third boundary line is obtained, including:

[0055] According to the pixel accuracy and the number of pixels between the second boundary line and the third boundary line, the distance between the second boundary line and the third boundary line is obtained.

[0056] At this time, according to the pixel accuracy and the number of pixels between the second boundary line and the third boundary line, the distance between the second boundary line and the third boundary line is obtained, which is beneficial to improve the detection efficiency.

[0057] Optionally, the welding mark detection method further comprises the following steps:

[0058] According to the first image and the first preset recognition model, the number of welding mark structures is obtained.

[0059] At this time, the welding mark detection method can improve the detection efficiency of the number of welding mark structures by using the first image and the first preset recognition model.

[0060] Optionally, before the step of obtaining the number of welding mark structures according to the first image and the first preset recognition model, the welding mark detection method further comprises the following steps:

[0061] At least one first training image is obtained from the front of the current collector sheet, and the first training image at least includes an image of the welding mark structure;

[0062] The number of welding mark structures in the first training image is labeled;

[0063] According to the first training image after the number labeling, the first preset recognition model is formed.

[0064] At this time, the welding mark detection method can form a more accurate first preset recognition model by using the first training image and labeling the number of welding mark structures, thereby improving the detection accuracy by using the first preset recognition model.

[0065] Optionally, the welding mark detection method further comprises the following steps:

[0066] Based on the irradiation of the film area, a second image is obtained from the front of the current collector sheet, and the second image at least includes an image of the film area.

[0067] At this time, the welding mark detection method can detect the forming quality of the film area by obtaining the second image; in addition, the welding mark detection method can obtain the first image and the second image at the same time based on the irradiation of the film area, thereby improving the detection efficiency.

[0068] Optionally, the welding mark detection method further comprises the following steps:

[0069] According to the second image and a second preset recognition model, wrinkles or a tab are obtained in the second image.

[0070] At this time, the welding mark detection method can improve the detection efficiency of wrinkles or a tab in the film area by according to the second image and the second preset recognition model.

[0071] The application also proposes a current collector production method, which comprises the following steps:

[0072] The current collector for lithium batteries is prepared, which comprises a film area and a tab welding area, the film area is provided with a plurality of through holes, and the tab welding area is provided with a welding mark structure;

[0073] For at least part of the number of the prepared current collectors, the tab welding area is irradiated from the front surface of the current collector, so that the welding mark structure is bright and the tab welding area outside the welding mark structure is dark;

[0074] The film area is irradiated from the back surface of the current collector;

[0075] A first image is obtained from the front surface of the current collector, which at least includes the image of the welding mark structure and the image of the through hole.

[0076] The current collector production method in the technical scheme of the application can make the welding mark structure bright and the tab welding area outside the welding mark structure dark by irradiating the tab welding area from the front surface of the current collector, and make the film area bright by irradiating the film area from the back surface of the current collector, so that the contrast between the tab welding area outside the welding mark structure and the film area in the first image obtained from the front surface by the first camera is enhanced, and the detection success rate of the edge of the tab welding area is improved.

[0077] In addition, the first image is obtained by irradiating the tab welding area and irradiating the film area, so that the first image can contain the image of the tab welding area and the image of the welding mark structure at the same time, the number of shooting times is reduced, and the detection efficiency is improved.

[0078] Optionally, the step of preparing the current collector for lithium batteries comprises:

[0079] A plurality of arrayed through holes are formed;

[0080] A plurality of welding mark structures are formed, and the arrangement direction of the welding mark structures is parallel to the arrangement direction of the through holes.

[0081] At this time, the current collector tab production method can make the arrangement direction of the welding structure parallel to the arrangement direction of the through hole, so that the through hole can be used as a positioning reference for the welding structure, thereby improving the detection efficiency of detecting the distance of the welding structure.

[0082] The above description is only a summary of the technical solutions of the present application. In order to more clearly understand the technical means of the present application, the following specific embodiments of the present application can be implemented according to the content of the specification, and in order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the following specific embodiments of the present application are described. BRIEF DESCRIPTION OF DRAWINGS

[0083] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can obtain other drawings according to the structures shown in these drawings without creative labor.

[0084] Fig. 1 is a top view of an embodiment of a welding detection system in the related art;

[0085] Fig. 2 is a detection image of a whole piece of solid current collector in the related art;

[0086] Fig. 3 is a detection image of a current collector with a through hole in the related art;

[0087] Fig. 4 is a partial enlarged view of a film area of the current collector in Fig. 3;

[0088] Fig. 5 is a top view of an embodiment of a welding detection system provided by the present application;

[0089] Fig. 6 is a left view of an embodiment of a welding detection system provided by the present application;

[0090] Fig. 7 is a schematic view of the change of a detection image in an embodiment of the present application;

[0091] Fig. 8 is a structural schematic view of a detection image in an embodiment of the present application;

[0092] Fig. 9 is a structural schematic view of another detection image in an embodiment of the present application;

[0093] Fig. 10 is an effect diagram of another detection image in an embodiment of the present application;

[0094] Fig. 11 is a structural schematic view of still another detection image in an embodiment of the present application;

[0095] Fig. 12 is an effect diagram of still another detection image in an embodiment of the present application;

[0096] Fig. 13 is a schematic diagram of steps of an embodiment of the welding mark detection method provided by the present application;

[0097] Fig. 14 is a schematic diagram of steps of another embodiment of the welding mark detection method provided by the present application.

[0098] Brief Description of the Drawings: 100, current collecting sheet; 110, film area; 120, tab welding area; 121, welding mark structure; 210, front light source; 220, light emitter; 230, first camera; 240, barrel; 250, second camera; 260, mounting bracket.

[0099] The implementation, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings.

[0100] Embodiments of the present application

[0101] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some of the embodiments of the present application, but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0102] It should be noted that if the embodiments of the present application involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative positional relationship, movement condition, etc. between the components in a certain posture, and if the certain posture changes, the directional indications also change accordingly.

[0103] In addition, if the embodiments of the present application involve descriptions such as "first", "second", etc., the descriptions of "first", "second", etc. are only for description purposes, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include at least one of the features. In addition, "and / or" or "and / or" appearing throughout the text means that the three parallel solutions are included, for example, "A and / or B" includes A solution, or B solution, or A and B solutions are satisfied at the same time. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the fact that a person of ordinary skill in the art can realize it, and when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, and is not within the scope of protection claimed by the present application.

[0104] A lithium ion cell generally includes a positive current collector, a negative current collector, and a separator between the two, wherein the positive current collector generally includes a positive current collecting layer (usually an aluminum foil or a composite foil containing an aluminum layer) and an active material layer coated on the positive current collecting layer, and the negative current collector generally includes a negative current collecting layer (usually a copper foil or a composite foil containing a copper layer) and an active material layer coated on the negative current collecting layer, wherein the positive active material includes lithium nickel cobalt manganese oxide and lithium nickel cobalt aluminum oxide, and the negative active material includes graphite or carbon with a graphite-like structure.

[0105] After the positive current collector and the negative current collector are coated with active material and rolled to form a tab, some technologies use ultrasonic roll welding to connect the adapter piece to the tab to form a tab lug. At this time, a weld mark structure is formed. In related technologies, one side of the weld mark structure is a recess close to a rectangle, and the other side of the weld mark structure is a protrusion close to an ellipse.

[0106] In related technologies, visual detection is usually used to detect the distance of the weld mark structure to the active material layer, the overall width of the weld mark structure, or the number of weld mark structures. However, sometimes it is difficult to determine the edge of the weld mark structure, and the detection success rate needs to be improved.

[0107] Therefore, based on the above considerations, in order to improve the detection success rate, the present application provides a weld mark detection system. When the weld mark detection system is used, the front light source irradiates the tab lug welding area from the front of the current collector, so that the weld mark structure is bright and the tab lug welding area outside the weld mark structure is dark, and the back light roller irradiates the film area from the back of the current collector, so that the film area is bright. Therefore, the contrast of the tab lug welding area outside the weld mark structure and the film area in the first image obtained by the first camera from the front is enhanced, so as to improve the detection success rate of the edge of the tab lug welding area.

[0108] FIG. 1 shows a top view of an embodiment of a weld mark detection system in related technologies. Related technologies usually set a light source 210a and a camera 230a on the front of the current collector 120a, for example, on the upper side of the current collector 120a. Referring to FIGS. 1 and 2, related technologies use the light source 210a to make the weld mark structure 121a bright and the adapter piece 120a outside the weld mark structure 121a dark, and form a bright area between the weld mark structure 121a on the current layer and the active material layer (the active material layer can be understood as a film area, which can be referred to FIG. 2), thereby performing image visual detection on the weld mark structure 121a.

[0109] However, the active material area of part of the current collector tab is changed from a non-transparent whole entity structure (see FIG. 2) to a through hole in the form of a mesh hole or the like (for example, a porous copper foil is used for the negative current collector layer), and the adapter tab covers the active material layer; for example, the current collector tab 100 shown in FIG. 3 includes a film area 110 (for example, an area coated with an active material layer) and a tab welding area 120 (for example, an area where the adapter tab is located), the film area 110 and the tab welding area 120 are arranged along the surface of the current collector tab 100, the film area 110 is provided with a plurality of through holes, the through holes penetrate the thickness of the current collector tab 100, and the tab welding area 120 is provided with a welding mark structure 121 (for example, a welding mark or the like).

[0110] 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 welding mark structure 121 and the film area 110 where the active material layer is located to be dark, 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 dark, making it difficult to determine the edge condition of the welding mark structure 121 and the tab welding area 120. Since the through hole in the form of a micro-hole on the current collector layer, a mesh hole on the active material area, and the like is relatively small, for example, referring to FIGS. 3 and 4, the ratio of the aperture of the through hole on the current collector layer to the diameter of the envelope circle of the welding mark structure 121 is less than or equal to 0.1, and in some products, the ratio is less than or equal to 0.05, or even less than 0.01, so it is usually difficult to find light passing through without being reflected back to the camera.

[0111] Next, the structure of the welding mark detection system proposed in the present application will be explained in detail with specific embodiments. In an embodiment of the present application, referring to FIGS. 5 and 6, the welding mark detection system is used to detect the current collector tab 100, the current collector tab 100 includes a film area 110 and a tab welding area 120, the film area 110 and the tab welding area 120 are arranged along the surface of the current collector tab 100; the film area 110 is provided with a plurality of through holes, the through holes penetrate the thickness of the current collector tab 100; the tab welding area 120 is provided with a welding mark structure 121, the welding mark detection system includes a front light source 210, a back light roller, a first camera 230, and an upper computer, the front light source 210 is used to irradiate the tab welding area 120 from the front of the current collector tab 100, so that the welding mark structure 121 is bright and the tab welding area 120 outside the welding mark structure 121 is dark; the back light roller is used to support the back of the current collector tab 100 and irradiate the film area 110 from the back of the current collector tab 100; the first camera 230 is used to acquire a first image from the front of the current collector tab 100, the first image at least includes the image of the welding mark structure 121 and the image of the through hole; the upper computer is used to acquire the first image by the first camera 230 based on the front light source 210 irradiating the tab welding area 120 and the back light roller irradiating the film area 110.

[0112] The current collector tab 100 can be a single positive electrode tab or a single negative electrode tab. The current collector tab 100 can also be two or more positive electrode tabs or two or more negative electrode tabs stacked together, for example, two or more positive electrode tabs or two or more negative electrode tabs are stacked together for detection. The first camera 230 can be a line scan camera or a CCD (Charge Coupled Device) camera, and the like, which is not limited in the embodiment.

[0113] The front surface and the back surface of the current collector tab 100 can be understood as two surfaces with relatively large areas of the current collector tab 100, for example, the front surface and the back surface of FIGS. 5 and 6 are arranged upward and downward, respectively. Referring to FIGS. 5 and 6 (where FIGS. 5 and 6 respectively show a top view and a left view of an embodiment of the welding mark detection system provided by the present application), the front surface light source 210 is used to irradiate the tab welding area 120 from the upper side of the current collector tab 100, so that the welding mark structure 121 is bright and the tab welding area 120 outside the welding mark structure 121 is dark; in particular, the reflection or diffuse reflection characteristics of the welding mark structure 121 and the tab welding area 120 outside the welding mark structure 121 can be combined, and the light angle of the front surface light source 210 can be adjusted to make the welding mark structure 121 bright and the tab welding area 120 outside the welding mark structure 121 dark. It can be understood that, since the welding mark structure 121 has protrusions or depressions, the welding mark structure 121 is more likely to reflect light in all directions, so the welding mark structure 121 is more likely to be illuminated than the tab welding area 120 outside the welding mark structure 121. The back light roller is used to irradiate the film area 110 from the lower side of the current collector tab 100, so that the light of the back light roller passes through the through hole on the film area 110 and reaches the first camera 230.

[0114] The host computer can be a terminal device, such as a computer, a PLC (Programmable Logic Controller) controller, and the like. The host computer is used to acquire the first image based on the front surface light source 210 irradiating the tab welding area 120 and the back light roller irradiating the film area 110 to make the first camera 230 acquire the first image; it can be understood that the host computer can be configured to make the first camera 230 acquire the first image when the front surface light source 210 irradiates the tab welding area 120 and the back light roller irradiates the film area.

[0115] The image change detection diagram in an embodiment of the present application is shown in FIG. 7. Referring to FIG. 7, the current collector sheet 100 includes the film area 110 (the film area 110 can be understood as an area that is transparent due to the through holes, mesh holes and other types of through holes) arranged along the film layer surface of the current collector sheet 100 and the tab welding area 120, and the tab welding area 120 is provided with the welding mark structure 121. For example, referring to FIGS. 6 and 7, the current collector sheet 100 can be arranged to be conveyed along the Y-axis direction; referring to FIGS. 7 and 8, the film area 110 and the tab welding area 120 are arranged along the X-axis direction. It can be understood that, along the conveying direction of the current collector sheet 100, the tab welding area 120 is arranged beside the film area 110; and along the conveying direction of the current collector sheet 100, the film area 110 can be arranged on both sides of the tab welding area 120.

[0116] The tab can be formed by connecting the adapter piece to the film area 110 where the active material layer is located, and a plurality of welding mark structures 121 can be formed during the connection. At this time, the tab welding area 120 includes the area where the adapter piece is located. In addition, the tab welding area 120 where the adapter piece is located can cover the film area 110 where the active material layer is located, or the edge of the tab welding area 120 where the adapter piece is located can abut against the edge of the film area 110 where the active material layer is located. It can be understood that the film area 110 is connected to the tab welding area 120.

[0117] The welding mark detection system in the technical solution of the present application can make the welding mark structure 121 bright and the tab welding area 120 outside the welding mark structure 121 dark by making the front light source 210 irradiate the tab welding area 120 from the front of the current collector sheet 100, and can make the film area 110 bright by making the back light roller irradiate the film area 110 from the back of the current collector sheet 100, so that the contrast between the tab welding area 120 outside the welding mark structure 121 and the film area 110 in the first image obtained by the first camera 230 from the front is enhanced, and the detection success rate of the edge of the tab welding area 120 is improved. For example, referring to FIG. 7, the detection image obtained by the related art on the left side of the figure is changed to the detection image obtained by the above-mentioned embodiment of the present application on the right side of the figure; after the change, the contrast between the tab welding area 120 outside the welding mark structure 121 and the film area 110 is enhanced, and the boundary between the tab welding area 120 and the film area 110 is more obvious.

[0118] In addition, the host computer can make the first camera 230 obtain the first image by making the front light source 210 irradiate the tab welding area 120 and the back light roller irradiate the film area 110, so that the first image can contain the image of the tab welding area 120 and the image of the welding mark structure 121 at the same time, the number of shooting times required by the whole process is reduced, and the detection efficiency is improved.

[0119] With reference to FIGS. 5 and 6, in some embodiments, the backlight roller comprises a barrel 240 for abutting the back surface of the current collector sheet 100, for example, the barrel 240 abuts the lower surface of the current collector sheet 100 in FIG. 6. The barrel 240 can be understood as a barrel capable of rolling or rotating, for example, rotating along the U direction in FIG. 6, so as to move relative to the current collector sheet 100 during the conveying of the current collector sheet 100, or drive the current collector sheet 100 to move, or be driven by the current collector sheet 100 to move.

[0120] In some embodiments, the welding mark detection system can further comprise a traction roller for supporting the current collector sheet 100 and driving the current collector sheet 100 to move forward. At this time, the current collector sheet 100 can be provided with a forward movement force by the traction roller, reducing the power output requirement of the backlight roller on the current collector sheet, reducing the friction requirement between the barrel 240 and the current collector sheet 100, making the preparation of the barrel 240 more flexible and convenient. Of course, the welding mark detection system can further comprise a driven roller, and the traction roller, the backlight roller and the driven roller are arranged in sequence, at this time the backlight roller is used as a driven roller. Of course, when the driven roller is not arranged, the backlight roller can also be used as a driven roller.

[0121] The light emitter 220 is at least partially arranged in the barrel 240, including that the light emitter 220 is partially arranged in the barrel 240, or the light emitter 220 is entirely arranged in the barrel 240. The barrel 240 is at least partially made of light-transmitting material, so that the light of the light emitter 220 can be irradiated to the film area 110. The barrel 240 can be made of transparent, translucent plastic or glass and the like.

[0122] In this embodiment, the barrel 240 can support the current collector sheet 100 by abutting the back surface of the current collector sheet 100, and can also reduce the overall space occupation of the welding mark detection system (which can be understood as the welding mark detection system is relatively compact) by arranging the light emitter 220 at least partially in the barrel 240, and reduce the risk of damage to the light emitter 220 by external objects such as seam welding devices and transport vehicles.

[0123] In some embodiments, the light emitter 220 can be arranged as a linear light source, and the light of the light emitter 220 is parallel to the axis of the barrel 240; the barrel 240 is made of light-uniform material, for example, the barrel 240 can be arranged as a white light-uniform plate made of polycarbonate, so that the light irradiated to the barrel 240 by the light emitter 220 can be uniformly transmitted outward, so as to uniformly illuminate the film area 110 and the tab welding area 120.

[0124] In some embodiments, the welding mark detection system further comprises a stroke sensor configured to detect a rolling stroke of the cylinder 240. The stroke sensor can be a rotary encoder or the like, which can be installed on a rotating structure corresponding to the rotating shaft of the cylinder 240 or a motor. The host computer can be configured to control the first camera 230 to capture the first image according to a preset correspondence between the rolling stroke and the first image. It can be understood that the first image device has a certain width of the shooting range, and thus the first camera 230 does not need to capture the first image continuously. The first camera 230 can be controlled to capture the first image according to a preset interval point on the rolling stroke. For example, the first camera 230 can be controlled to capture the first image when the rolling stroke reaches a preset distance value. The rolling stroke can be the rotation angle of the rotating structure corresponding to the rotating shaft of the cylinder 240 or the number of pulses output by the stroke sensor.

[0125] In this embodiment, the host computer controls the first camera 230 to capture the first image according to the preset correspondence between the rolling stroke and the first image, which can reduce the number of times of capturing the first image and improve the automation degree of the welding mark detection system. The automation degree can be improved by setting the execution time sequence in the host computer.

[0126] In some embodiments, referring to FIGS. 5 and 6, the current collector 100 is configured to move along the circumferential direction of the cylinder 240, for example, the current collector 100 is configured to move along the Y direction in the drawing for conveying. The first camera 230 comprises a line-scan camera, and the line-scan line of the line-scan camera is parallel to the axial direction of the cylinder 240. The line-scan camera can also be referred to as a line array camera, which performs line-by-line scanning. Each scanning line (line-scan line) has a large length and a small width, and the whole line-scan camera has a line shape. In this embodiment, as the current collector 100 moves along the circumferential direction of the cylinder 240, the line-scan line of the line-scan camera is parallel to the axial direction of the cylinder 240, so that continuous imaging can be achieved.

[0127] In this embodiment, since the welding mark structure 121 is usually formed on the side of the conveying direction of the current collector 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.

[0128] In some embodiments, referring to FIG. 5, the welding mark detection system comprises at least two first cameras 230, which are arranged along the axial direction of the cylinder 240, for example, along the X axis direction in FIG. 5. Along the conveying direction of the current collector 100, the two sides of the film area 110 are respectively provided with the tab welding area 120. The two first cameras 230 are configured to capture the images of the tab welding area 120 and the adjacent through hole, respectively.

[0129] For example, the first camera 230 includes at least two line scan cameras 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 conveying direction of the current collector tab 100, the two sides of the film area 110 are respectively provided with the tab welding area 120, and the two line scan cameras are used to respectively acquire images of the tab welding area 120 and the adjacent through hole.

[0130] 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 tab 100 provided with the tab welding area 120 on both sides, for example, the first camera 230 on both sides respectively detects the welding mark structure 121 of the tab welding area 120 on both sides of the film area 110.

[0131] In some embodiments, referring to FIGS. 5 and 6, the welding mark detection system further includes a second camera 250, and the second camera 250 and the first camera 230 are arranged in the conveying direction of the current collector tab 100, for example, the second camera 250 and the first camera 230 are arranged in the Y-axis direction or the U direction in FIG. 6. The second camera 250 is used to acquire a second image from the front of the current collector tab 100, and the second image at least includes an image of the film area 110. The host computer is used to make the second camera 250 acquire the second image based on the backlight roller irradiating the film area 110, which can be understood as that the host computer makes the second camera 250 acquire the second image under the condition that the backlight roller irradiates the film area 110. It can be understood that the second camera 250 can be a line scan camera or a CCD (Charge Coupled Device, charge coupled device) camera, and the present embodiment does not limit this.

[0132] In this embodiment, the welding mark detection system can acquire the second image through the second camera 250, so as to detect the forming quality of the film area 110 according to the second image, for example, whether there is a wrinkle or a connecting belt. Wherein, the current collector tab 100 is relatively fragile and sometimes breaks, at which time the connecting belt can be used to connect the current collector tab 100 to keep continuous at the breaking point. The detection image of the wrinkle can refer to FIG. 9 or FIG. 10, and the detection image of the connecting belt can refer to FIG. 11 or FIG. 12.

[0133] In addition, the backlight roller can be used to acquire the first image and the second image at the same time, which can be understood as being used to provide light to the first camera 230 and the second camera 250 at the same time to help acquire the first image and the second image, thereby improving the utilization rate of the backlight roller and the degree of simplification of the welding mark detection system.

[0134] The cylinder 240 can be provided with 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, so that the back light roller can provide light to the first camera 230 and the second camera 250, respectively. It can be understood that, during the rotation of the back light roller and the cylinder 240, the rotation speed of the back light roller and the cylinder 240 can be matched with the shooting time of the first camera 230 and the second camera 250, so that the first light-transmitting area is arranged opposite to the first camera 230 when the first camera 230 shoots, and the second light-transmitting area is arranged opposite to the second camera 250 when the second camera 250 shoots.

[0135] In this embodiment, the second camera 250 and the first camera 230 are arranged at intervals along the circumferential direction of the cylinder 240, which can reduce the shooting interference between them, and can cover the light-emitting surface of the back light roller to a greater extent, thereby improving the utilization rate of the back light roller and reducing the illumination and interference of the back light roller to the outside world.

[0136] In some embodiments, referring to FIG. 6, the first camera 230 can be arranged above the cylinder 240, and the second camera 250 can be arranged 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 back light roller to a greater extent, and further reduce the illumination and interference of the back light roller to the outside world.

[0137] In some embodiments, the back light roller is used to provide adjustable light intensity to the film area 110, for example, the back light roller is provided as a light source with adjustable light intensity, for example, the internal light emitter 220 is provided 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 provided as a structure with adjustable opening area, such as a louver.

[0138] In this embodiment, the back light 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, which is respectively beneficial to adjust the contrast between the tab welding area 120 and the film area 110 of the welding mark detection system, and improve the detection adaptability of the welding mark detection system to different materials of the current collector plate 100.

[0139] In some embodiments, referring to FIG. 5, the light beam axis of the front light source 210 and the light beam axis of the first camera 230 have an included angle, and the included angle between the light beam axis of the front light source 210 and the surface of the film layer of the current collector plate 100 is less than or equal to 45 degrees, so that the overall layout between the front light source 210 and the first camera 230 is more compact, and the compactness of the welding mark detection system is improved.

[0140] In some embodiments, the front light source 210 can include a first linear light source, a light line row of the first linear light source being parallel to the cross section of the cylinder 240, and the light line row of the first linear light source being parallel to the transport direction of the current collector tab 100; at this time, the width of the light line row of the first linear light source can cover the tab welding area 120 and the partial film area 110 adjacent to the tab welding area 120 (the remaining part of the film area 110 is not covered by the light line row of the first linear light source), so that the length of the light line row of the first linear light source is relatively long, so as to cover the shooting range of the first camera 230 (which can be a line scanning camera) in the length direction of the light line row and form redundancy, thereby improving the shooting quality through the length of the light line row and reducing the light energy consumption through the width of the light line row.

[0141] In some embodiments, the back light roller includes a second linear light source, a light line row of the second linear light source being parallel to the cross section of the cylinder 240, and the light line row of the second linear light source being parallel to the transport direction of the current collector tab 100; at this time, the width of the light line row of the second linear light source can cover the tab welding area 120 on the other side and the partial film area 110 adjacent to the tab welding area 120 (the remaining part of the film area 110 is not covered by the light line row of the second linear light source), so that the length of the light line row of the second linear light source is relatively long, so as to cover the shooting range of the other first camera 230 (which can be a line scanning camera) in the length direction of the light line row and form redundancy, thereby improving the shooting quality through the length of the light line row and reducing the light energy consumption through the width of the light line row.

[0142] In some embodiments, referring to FIG. 5, the welding mark detection system further includes a mounting bracket 260, wherein the mounting bracket 260 can be provided as an integral structure, and the mounting bracket 260 can also include at least two spaced-apart bracket sub-bodies. The first camera 230, the front light source 210, and the second camera 250 are respectively movably connected with the mounting bracket 260 along the axial direction of the cylinder 240, for example, through a sliding groove, a guide rail or the like, so that the first camera 230, the front light source 210, and the second camera 250 can respectively adjust the working position, so as to irradiate or shoot different positions of the current collector tab 100, thereby improving the use flexibility of the welding mark detection system.

[0143] The present application also proposes a welding mark detection method, which is used for detecting the above-mentioned current collector tab 100; wherein the welding mark detection method can be executed based on the above-mentioned welding mark detection system, for example, at least part of the steps of the welding mark detection method can be executed by the above-mentioned upper computer.

[0144] Referring to FIG. 13, the welding mark detection method includes the following steps:

[0145] Step S100, irradiate the tab welding area 120 from the front surface of the current collector tab 100, so that the solder structure 121 is bright and the tab welding area 120 outside the solder structure 121 is dark; wherein the irradiation can be performed by the front light source 210 described above.

[0146] Step S200, irradiate the film area 110 from the back surface of the current collector tab 100, which can be performed by the back light roller described above; wherein the step S100 and the step S200 can be executed in sequence before the step S300, or can be executed in parallel before the step S300, which is not limited in the embodiment.

[0147] Step S300, obtain the first image from the front surface of the current collector tab 100, the first image at least includes the image of the solder structure 121 and the image of the through hole, which can be obtained by the first camera 230 described above.

[0148] The solder detection method in the technical solution of the present application can make the solder structure 121 bright and the tab welding area 120 outside the solder structure 121 dark by irradiating the tab welding area 120 from the front surface of the current collector tab 100, and make the film area 110 bright by irradiating the film area 110 from the back surface of the current collector tab 100, so that the contrast between the tab welding area 120 outside the solder structure 121 and the film area 110 in the first image obtained by the first camera 230 from the front surface is enhanced, and the detection success rate of the edge of the tab welding area 120 is improved.

[0149] In addition, the first image is obtained by irradiating the tab welding area 120 and the film area 110, so that the first image can contain the image of the tab welding area 120 and the image of the solder structure 121 at the same time, which reduces the number of shooting times required overall and improves the detection efficiency.

[0150] In some embodiments, the step of obtaining the first image from the front surface of the current collector tab 100 (the step S300 described above) comprises:

[0151] Detect the rolling stroke of the cylinder body 240, which is used to abut against the back surface of the current collector tab 100, for example, the rolling stroke of the cylinder body 240 can be detected by the stroke sensor described above;

[0152] Obtain the first image according to the rolling stroke and a preset corresponding relationship, for example, the first image can be obtained when the rolling stroke reaches a preset distance value.

[0153] In this embodiment, since the first image has a certain width, obtaining the first image according to the rolling stroke and the preset corresponding relationship can reduce the number of shooting times of the first image device and improve the automation degree of the solder detection method.

[0154] In some embodiments, the welding mark detection method further comprises the following steps:

[0155] The at least two first cameras 230 are arranged along the axial direction of the cylinder 240, and the cylinder 240 is used to abut the back surface of the current collector 100; wherein, along the transportation direction of the current collector 100, the two sides of the film area 110 are respectively provided with the tab welding area 120;

[0156] The step of obtaining the first image from the front surface of the current collector 100 (the above-mentioned step S300) comprises:

[0157] The images of the tab welding area 120 and the adjacent through hole are respectively obtained.

[0158] In this embodiment, based on the arrangement of the first cameras 230 along the axial direction of the cylinder 240, the images of the tab welding area 120 and the adjacent through hole are respectively obtained, which is beneficial to improve the detection efficiency of the current collector 100 with the tab welding area 120 on both sides.

[0159] Referring to FIG. 14, in some embodiments, the welding mark detection method can further comprise the following steps:

[0160] Step S410: obtaining a first boundary line of the through hole according to the first image, the first boundary line being towards the tab welding area 120; wherein, the first boundary line can refer to the boundary line a in FIG. 8;

[0161] Step S420: obtaining a second boundary line of the welding mark structure 121 according to the first image, the second boundary line being towards the film area 110; wherein, the second boundary line can refer to the boundary line b in FIG. 8; wherein, the step S410 and the step S420 can be executed in sequence before the following step S430, or can be executed in parallel before the following step S430, and the present embodiment does not limit this;

[0162] Step S430: obtaining the distance from the welding mark structure 121 to the first boundary line a according to the first boundary line a, the second boundary line b and the image parameters corresponding to the first image, for example, obtaining the distance between the boundary lines a and b in FIG. 8.

[0163] In this embodiment, the welding mark detection method can improve the detection efficiency of detecting the distance from the welding mark structure 121 to the first boundary line a by the first boundary line a, the second boundary line b and the image parameters corresponding to the first image, which is beneficial to find the distance abnormality of the welding mark structure 121 as early as possible.

[0164] In some embodiments, the image parameters corresponding to the first image include pixel accuracy;

[0165] According to the first boundary line, the second boundary line and the image parameters corresponding to the first image, the step of obtaining the distance from the weld mark structure 121 to the first boundary line (the above-mentioned step S430) comprises:

[0166] According to the pixel precision, the number of pixels between the first boundary line and the second boundary line, the distance from the weld mark structure 121 to the first boundary line is obtained; for example, the distance from the weld mark structure 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.

[0167] In this embodiment, according to the pixel precision, the number of pixels between the first boundary line and the second boundary line, the distance from the weld mark structure 121 to the first boundary line is obtained, which is beneficial to improve the detection efficiency.

[0168] Referring to FIG. 14, in some embodiments, the weld mark detection method further comprises the following steps:

[0169] Step S510, according to the first image, obtaining the second boundary line and the third boundary line of the weld mark structure 121, the second boundary line faces the film area 110, and the third boundary line faces away from the film area 110; wherein the second boundary line can refer to the boundary line b in FIG. 8, and the third boundary line can refer to the boundary line c in FIG. 8; it can be understood that if it is necessary to obtain the above-mentioned first boundary line a, second boundary line b and 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 executed in sequence or in parallel; in addition, the above-mentioned first boundary line a, second boundary line b and third boundary line c can be respectively identified by image recognition according to pixel characteristics such as pixel gray scale. When each through hole is arranged at intervals, the above-mentioned first boundary line a can be fitted by forming an envelope line of the through hole; when each weld mark structure 121 is arranged at intervals, the above-mentioned second boundary line b and third boundary line c can be fitted by forming an envelope line of the weld mark structure 121;

[0170] Step S520, according to the second boundary line b, the third boundary line c and the image parameters corresponding to the first image, obtaining the distance between the second boundary line b and the third boundary line c, for example, obtaining the distance between the boundary lines b and c in FIG. 8.

[0171] In this embodiment, the weld mark detection method can improve the detection efficiency of detecting the overall width of the weld mark structure 121 by the second boundary line b, the third boundary line c and the image parameters corresponding to the first image, which is beneficial to find out the abnormal situation of the overall width of the weld mark structure 121 as soon as possible.

[0172] In some embodiments, the image parameters corresponding to the first image comprise pixel precision;

[0173] According to the image parameters corresponding to the second boundary line, the third boundary line and the first image, the step (step S520) of obtaining the distance between the second boundary line and the third boundary line comprises:

[0174] According to the pixel quantity between the second boundary line b and the third boundary line c and the pixel precision, the distance between the second boundary line b and the third boundary line c is obtained; for example, the distance between the second boundary line b and the third boundary line c is obtained by multiplying the pixel quantity between the second boundary line b and the third boundary line c by the corresponding pixel precision.

[0175] In this embodiment, according to the pixel quantity between the second boundary line b and the third boundary line c and the pixel precision, the distance between the second boundary line b and the third boundary line c is obtained, which is beneficial to improve the detection efficiency.

[0176] In some embodiments, the welding mark detection method further comprises the following steps:

[0177] According to the first image and the first preset recognition model, the number of welding mark structures 121 is obtained, wherein the first preset recognition model can be a preset corresponding relationship or a preset recognition algorithm.

[0178] In this embodiment, the welding mark detection method can improve the detection efficiency of the number of welding mark structures 121 by using the first image and the first preset recognition model.

[0179] In some embodiments, before the step of obtaining the number of welding mark structures 121 according to the first image and the first preset recognition model, the welding mark detection method further comprises the following steps:

[0180] At least one first training image is obtained from the front of the irradiated current collector 100, and the first training image at least includes an image of the welding mark structure 121, for example, the first camera 230 described above can be used to obtain the first training image;

[0181] The number of welding mark structures 121 in the first training image is labeled, for example, the welding mark structure 121 is labeled in the manner of 1, 2, 3, to n, wherein n is a positive integer;

[0182] According to the first training image after the number labeling, the first preset recognition model is formed, for example, the first preset recognition model can be formed by training a recognition algorithm.

[0183] In this embodiment, the welding mark detection method can form a more accurate first preset recognition model by using the first training image and the number labeling of the welding mark structure 121, thereby facilitating the improvement of detection accuracy by using the first preset recognition model.

[0184] Referring to FIG. 14, in some embodiments, the welding mark detection method further comprises the following steps:

[0185] At step S610, a second image is acquired from the front side of the current collector 100 based on the fact that the film region 110 is irradiated, and the second image at least includes an image of the film region 110. The second image can be acquired by the second camera 250.

[0186] In this embodiment, the welding mark detection method can detect the forming quality of the film region 110 by acquiring the second image, for example, to detect whether there is a wrinkle or a connecting strip. Since the current collector 100 is relatively fragile and may be broken at times, the connecting strip can be used to connect the current collector 100 to keep it continuous at the breaking point. The detection image of the wrinkle can refer to FIG. 9 or FIG. 10, and the detection image of the connecting strip can refer to FIG. 11 or FIG. 12. In addition, the welding mark detection method can acquire the first image and the second image at the same time based on the fact that the film region 110 is irradiated, thereby improving the detection efficiency.

[0187] Referring to FIG. 14, in some embodiments, the welding mark detection method further includes the following steps:

[0188] At step S620, a wrinkle or a connecting strip in the second image is acquired according to the second image and a second preset recognition model. The second preset recognition model can be a preset corresponding relationship or a preset recognition algorithm.

[0189] In this embodiment, the welding mark detection method can improve the detection efficiency of the wrinkle or the connecting strip in the film region 110 by acquiring the wrinkle or the connecting strip in the second image according to the second image and the second preset recognition model.

[0190] In some embodiments, before the step of acquiring the wrinkle or the connecting strip in the second image according to the second image and the second preset recognition model, the welding mark detection method further includes the following steps:

[0191] At least one second training image is acquired from the irradiated front side, and the second training image at least includes an image of the film region 110. The second training image can be acquired by the second camera 250.

[0192] The wrinkle or the connecting strip in the second training image is labeled.

[0193] The second preset recognition model is formed according to the labeled second training image. For example, the second preset recognition model can be formed by training a recognition algorithm.

[0194] In this embodiment, the welding mark detection method can form a more accurate second preset recognition model by using the second training image and labeling the wrinkle or the connecting strip in the second training image, thereby facilitating the improvement of the detection accuracy by using the second preset recognition model.

[0195] In this embodiment, the welding mark detection method further includes the following steps:

[0196] If the difference between the distance of the welding 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 value, or the difference between the distance of the second boundary line b of the welding mark structure 121 and the third boundary line c and the second preset distance value is greater than or equal to the second preset difference value, the prompt information is output; wherein the prompt information can be alarm information and the like. The first preset difference value and the second preset difference value can be set to be less than or equal to 0.5 millimeters.

[0197] Correspondingly, the welding mark detection system can include a corresponding prompt module, which can be included in the above host computer.

[0198] The application also proposes a current collector tab production method, which is used to produce the above-mentioned current collector tab 100. The current collector tab production method comprises the following steps:

[0199] Preparation of the above-mentioned current collector tab 100;

[0200] For at least a part of the number of current collector tabs 100 prepared, the tab welding area 120 of the current collector tab 100 is irradiated from the front surface, so that the welding mark structure 121 is bright and the tab welding area 120 outside the welding mark structure 121 is dark; wherein the irradiation can be specifically performed by the above-mentioned front light source 210;

[0201] The film area 110 of the current collector tab 100 is irradiated from the back surface, and the irradiation can be specifically performed by the above-mentioned back light roller;

[0202] The first image is obtained from the front surface of the current collector tab, and the first image at least includes the image of the welding mark structure 121 and the image of the through hole.

[0203] The current collector tab production method in the technical solution of the application can make the welding mark structure 121 bright and the tab welding area 120 outside the welding mark structure 121 dark by irradiating the tab welding area 120 from the front surface of the current collector tab 100, and can make the film area 110 bright by irradiating the film area 110 from the back surface of the current collector tab 100, so that the contrast between the tab welding area 120 outside the welding mark structure 121 and the film area 110 in the first image obtained by the first camera 230 from the front surface is enhanced, and the detection success rate of the edge of the tab welding area 120 is improved.

[0204] In addition, the first image is obtained by irradiating the tab welding area 120 and irradiating the film area 110, so that the first image can contain the image of the tab welding area 120 and the image of the welding mark structure 121 at the same time, the number of shooting times is reduced, and the detection efficiency is improved.

[0205] In some embodiments, the step of preparing the current collector tab 100 comprises:

[0206] Forming a plurality of through holes arranged in an array; for example, a plurality of through holes arranged in an array and penetrating the thickness of the current collector can be formed on the current collector, such as by laser processing or the like; then the active material layer is arranged on the current collector to form the tab segments, and the through holes are kept open to form the through holes.

[0207] Forming a plurality of welding structures 121, and the arrangement direction of the welding structures 121 is parallel to the arrangement direction of the through holes; for example, a plurality of welding structures 121 can be formed when the tabs are connected (such as by ultrasonic roll welding), the arrangement direction of the welding structures 121 is parallel to the arrangement direction of the through holes, and the tabs cover the active material layer or the edges of the tabs abut the edges of the active material layer; wherein the film area 110 includes the area where the active material layer extends beyond the tabs, and the tab welding area 120 includes the area where the tabs are located.

[0208] In this embodiment, the current collector production method can make the through holes serve as positioning references for the welding structures 121 by making the arrangement direction of the welding structures 121 parallel to the arrangement direction of the through holes, thereby improving the detection efficiency of detecting the distance of the welding structures 121.

[0209] In some embodiments, the steps of preparing the current collector 100 include:

[0210] Stacking at least two tab segments, and making the through holes of the tab segments on different stacks communicate; it can be understood that the current collector 100 can be two or more stacks of positive electrode films or negative electrode films, such as two or more stacks of positive electrode films or negative electrode films being stacked together for detection. At this time, the overall detection efficiency of the tab segments can be improved.

[0211] In some embodiments, the steps of preparing the current collector 100 include:

[0212] The current collector is formed by a copper foil or a composite foil containing a copper layer; and / or, the tab welding area 120 and the film area 110 are connected; and / or, the ratio of the aperture of the through hole on the current collector to the diameter of the envelope circle of the welding structure 121 is less than or equal to 0.1, including less than or equal to 0.05 or 0.01; and / or, the ratio of the aperture of the through hole on the stacked tab segments to the diameter of the envelope circle of the welding structure 121 is less than or equal to 0.1, including less than or equal to 0.05 or 0.01, when projected along the thickness direction of the tab segments. At this time, the overall weight of the current collector 100 can be reduced by the through hole on the current collector while detecting the welding structure 121.

[0213] With reference to FIGS. 5-12, the present application provides a welding mark detection system for detecting a current collector tab 100, the current collector tab 100 comprising a film area 110 and a tab welding area 120 arranged along a film layer surface of the current collector tab 100, the film area 110 being provided with a through hole penetrating through a thickness of the current collector tab 100, and the tab welding area 120 being provided with a welding mark structure 121, the welding mark detection system comprising a front light source 210, a back light roller, a first camera 230, and an upper computer, the front light source 210 being configured to irradiate the tab welding area 120 from a front surface of the current collector tab 100 so that the welding mark structure 121 is bright and the tab welding area 120 outside the welding mark structure 121 is dark; the back light roller being configured to irradiate the film area 110 from a back surface of the current collector tab 100, the back surface being arranged opposite to the front surface; the first camera 230 being configured to acquire a first image from the front surface of the current collector tab 100, the first image comprising at least an image of the welding mark structure 121 and an image of the through hole; and the upper computer being configured to cause the first camera 230 to acquire the first image based on the front light source 210 irradiating the tab welding area 120 and the back light roller irradiating the film area 110. The back light roller comprises a barrel 240 and a light emitter 220, the barrel 240 being configured to abut against the back surface of the current collector tab 100; and the light emitter 220 being at least partially arranged in the barrel 240, the barrel 240 being at least partially made of a light-transmitting material so that light rays of the light emitter 220 irradiate the film area 110. The welding mark detection system further comprises a traction roller configured to support and pull the current collector tab 100 forward; the light emitter 220 is arranged as a linear light source, the light rays of the light emitter 220 are parallel to an axial line of the barrel 240, and the barrel 240 is made of a light-uniform material. The welding mark detection system further comprises a travel sensor configured to detect a rolling travel of the barrel 240; and the upper computer is configured to cause the first camera 230 to acquire the first image according to the rolling travel and a preset corresponding relationship. The current collector tab 100 is configured to move along a circumferential direction of the barrel 240, and the first camera 230 comprises a line-scan camera, a line-scan line of the line-scan camera being parallel to an axial direction of the barrel 240. The welding mark detection system comprises at least two first cameras 230, the first cameras 230 being arranged along the axial direction of the barrel 240; along a conveying direction of the current collector tab 100, the film area 110 is provided with the tab welding area 120 on both sides thereof, and the two first cameras 230 are configured to acquire images of the tab welding areas 120 and the adjacent through holes, respectively. The welding mark detection system further comprises a second camera 250, the second camera 250 and the first camera 230 being arranged at intervals along the conveying direction of the current collector tab 100; the second camera 250 is configured to acquire a second image from the front surface, the second image comprising at least an image of the film area 110; and the upper computer is configured to cause the second camera 250 to acquire the second image based on the back light roller irradiating the film area 110.The current collector tab 100 is used for transportation along the circumferential direction of the cylinder 240, and the second camera 250 and the first camera 230 are arranged at intervals along the circumferential direction of the cylinder 240; the cylinder 240 comprises 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 the 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 comprises at least two line-scan cameras, the line-scan cameras 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 transportation direction of the current collector tab 100, the two sides of the film area 110 are respectively provided with the tab welding area 120, and the two line-scan cameras are used to respectively acquire the images of the tab welding area 120 and the adjacent through holes. The first camera 230 is arranged above the cylinder 240, and the second camera 250 is arranged in front of the cylinder 240. The first camera 230 and the second camera 250 have an included angle between the optical axis of the light beam and the optical axis of the light beam, and the included angle between the optical axis of the first light beam and the film layer surface of the current collector tab 100 is less than or equal to 45 degrees; the front light source 210 comprises a first linear light source, the light row of the first linear light source is parallel to the cross section of the cylinder 240, and the light row of the first linear light source is parallel to the transportation direction of the current collector tab 100; the backlight roller comprises a second linear light source, the light row of the second linear light source is parallel to the cross section of the cylinder 240, and the light row of the second linear light source is parallel to the transportation direction of the current collector tab 100. The welding mark detection system further comprises 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.

[0214] Referring to FIG. 14, the present application provides a welding mark detection method for detecting a current collector tab 100, the current collector tab 100 comprising a film area 110 and a tab welding area 120 arranged along the film layer surface of the current collector tab 100, the film area 110 being provided with a through hole penetrating the thickness of the current collector tab 100, and the tab welding area 120 being provided with a welding mark structure 121, the welding mark detection method comprising the following steps:

[0215] Irradiating the tab welding area 120 from the front of the current collector tab 100 so that the welding mark structure 121 is bright and the tab welding area 120 outside the welding mark structure 121 is dark;

[0216] Irradiating the film area 110 from the back of the current collector tab 100, the back being arranged opposite to the front;

[0217] Acquiring a first image from the front of the current collector tab 100, the first image comprising at least the image of the welding mark structure 121 and the image of the through hole.

[0218] The step of obtaining the first image from the front of the current collector sheet 100 comprises:

[0219] Detecting a rolling stroke of the cylinder 240, the cylinder 240 being configured to abut against the back of the current collector sheet 100;

[0220] Obtaining the first image according to the rolling stroke and a preset corresponding relationship.

[0221] The welding mark detection method further comprises the following steps:

[0222] At least two first cameras 230 are arranged along the axial direction of the cylinder 240, the cylinder 240 being configured to abut against the back of the current collector sheet 100; along the transport direction of the current collector sheet 100, the two sides of the film area 110 are respectively provided with tab welding areas 120;

[0223] The step of obtaining the first image from the front of the current collector sheet 100 comprises:

[0224] Respectively obtaining images of the tab welding area 120 and the adjacent through hole.

[0225] The welding mark detection method further comprises the following steps:

[0226] According to the first image, a first boundary line of the through hole is obtained, the first boundary line being directed towards the tab welding area 120;

[0227] According to the first image, a second boundary line of the welding mark structure 121 is obtained, the second boundary line being directed towards the film area 110;

[0228] According to the first boundary line, the second boundary line and the image parameters corresponding to the first image, a distance from the welding mark structure 121 to the first boundary line is obtained.

[0229] The image parameters corresponding to the first image comprise pixel accuracy;

[0230] The step of obtaining the distance from the welding mark structure 121 to the first boundary line according to the first boundary line, the second boundary line and the image parameters corresponding to the first image comprises:

[0231] According to the pixel accuracy, the number of pixels between the first boundary line and the second boundary line, the distance from the welding mark structure 121 to the first boundary line is obtained.

[0232] The welding mark detection method further comprises the following steps:

[0233] According to the first image, a second boundary line and a third boundary line of the welding mark structure 121 are obtained, the second boundary line being directed towards the film area 110, and the third boundary line being directed away from the film area 110;

[0234] According to the image parameters corresponding to the first image, the second boundary line and the third boundary line, a distance between the second boundary line and the third boundary line is obtained.

[0235] The image parameters corresponding to the first image include pixel accuracy.

[0236] According to the image parameters corresponding to the first image, the second boundary line and the third boundary line, a distance between the second boundary line and the third boundary line is obtained.

[0237] According to the pixel accuracy and the number of pixels between the second boundary line and the third boundary line, the distance between the second boundary line and the third boundary line is obtained.

[0238] The welding mark detection method further includes the following steps:

[0239] According to the first image and the first preset identification model, the number of welding mark structures 121 is obtained.

[0240] Before the step of obtaining the number of welding mark structures 121 according to the first image and the first preset identification model, the welding mark detection method further includes the following steps:

[0241] At least one first training image is obtained from the front surface of the irradiated collector, and the first training image at least includes an image of the welding mark structure 121.

[0242] The welding mark structure 121 in the first training image is labeled in number.

[0243] According to the first training image after number labeling, the first preset identification model is formed.

[0244] The welding mark detection method further includes the following steps:

[0245] Based on the irradiation of the film area 110, a second image is obtained from the front surface of the current collector 100, and the second image at least includes an image of the film area 110.

[0246] The welding mark detection method further includes the following steps:

[0247] According to the second image and the second preset identification model, the wrinkle or the tab in the second image is obtained.

[0248] Before the step of obtaining the wrinkle or the tab in the second image according to the second image and the second preset identification model, the welding mark detection method further includes the following steps:

[0249] At least one second training image is obtained from the front surface of the irradiated current collector 100, and the second training image at least includes an image of the film area 110.

[0250] The wrinkle or the tab in the second training image is labeled.

[0251] According to the second labeled training image, a second preset recognition model is formed.

[0252] The application provides a current collector tab production method, which comprises the following steps:

[0253] A current collector tab 100 is prepared, which comprises a film area 110 and a tab welding area 120 arranged along the surface of the film layer of the current collector tab 100, the film area 110 is provided with a through hole penetrating through the thickness of the current collector tab 100, and the tab welding area 120 is provided with a welding mark structure 121;

[0254] For at least a part of the prepared current collector tabs 100, the tab welding area 120 is irradiated from the front surface of the current collector tab 100, so that the welding mark structure 121 is bright and the tab welding area 120 outside the welding mark structure 121 is dark;

[0255] The film area 110 is irradiated from the back surface of the current collector tab 100, and the back surface is arranged opposite to the front surface;

[0256] A first image is obtained from the front surface of the current collector tab 100, and the first image at least comprises an image of the welding mark structure 121 and an image of the through hole.

[0257] The step of preparing the current collector tab 100 comprises the following steps:

[0258] A plurality of through holes penetrating through the thickness of the current collector tab 100 are formed in an array;

[0259] A plurality of welding mark structures 121 are formed, and the arrangement direction of the welding mark structures 121 is parallel to the arrangement direction of the through holes.

[0260] The step of preparing the current collector tab 100 comprises the following steps:

[0261] A plurality of through holes penetrating through the thickness of the current collector tab 100 are formed in an array;

[0262] An active material layer is arranged on the current collector layer to form a tab segment, and the through hole is kept conductive to form a through hole;

[0263] An adapter piece is connected to the tab segment, a plurality of welding mark structures 121 are formed during the connection, the arrangement direction of the welding mark structures 121 is parallel to the arrangement direction of the through holes, the adapter piece covers the active material layer or the edge of the adapter piece abuts against the edge of the active material layer, the film area 110 comprises an area where the active material layer extends out of the adapter piece, and the tab welding area 120 comprises an area where the adapter piece is located.

[0264] The step of preparing the current collector tab 100 comprises the following steps:

[0265] At least two tab segments are stacked, and the through holes of the tab segments on different layers are connected.

[0266] The step of preparing the current collecting sheet 100 comprises:

[0267] The current collecting layer is formed by a copper foil, or by a composite foil comprising a copper layer;

[0268] The tab welding area 120 and the film area 110 are connected;

[0269] The ratio of the aperture of the through hole on the current collecting layer to the diameter of the envelope circle of the welding mark structure 121 is less than or equal to 0.1;

[0270] The ratio of the aperture of the through hole on the current collecting layer to the diameter of the envelope circle of the welding mark structure 121 is less than or equal to 0.1.

[0271] It can be understood that the specific structure of the welding mark detection method and the current collecting sheet production method refers to the above-mentioned embodiments of the welding mark detection system. Since the welding mark detection method and the current collecting sheet production method adopt all the technical solutions of the above-mentioned embodiments, at least all the beneficial effects brought by the technical solutions of the above-mentioned embodiments are possessed, and thus it is not necessary to repeat them here.

[0272] The above only describes the preferred embodiments of the present application, and does not limit the patent scope of the present application. Any equivalent structural transformation, direct / indirect application in other related technical fields based on the technical concept of the present application, and the content of the present application and the drawings are included in the patent protection scope of the present application.

Claims

1. A flash detection system, characterized by, The welding mark detection system is used for detecting a current collector tab of a lithium battery, the current collector tab comprises a film area and a tab welding area, the film area is provided with a plurality of through holes, the tab welding area is provided with a welding mark structure, and the welding mark detection system comprises: a front light source, which is used for irradiating the tab welding area from the front of the current collector tab, so that the welding mark structure is bright and the tab welding area outside the welding mark structure is dark; a back light roller, which is used for supporting the back of the current collector tab and irradiating the film area from the back of the current collector tab; a first camera, which is used for acquiring a first image from the front of the current collector tab, the first image at least comprising an image of the welding mark structure and an image of the through hole; a host computer, which is used for enabling the first camera to acquire the first image based on the front light source irradiating the tab welding area and the back light roller irradiating the film area.

2. The weld detection system of claim 1, wherein, The back light roller comprises a barrel and a light emitter, the light emitter is at least partially arranged in the barrel, the barrel is used for abutting against the back of the current collector tab; the barrel is at least partially made of a light-transmitting material, so that the light of the light emitter irradiates the film area.

3. The weld detection system of claim 2, wherein, The welding mark detection system further comprises a traction roller, which is used for supporting the current collector tab and pulling the current collector tab to move forward; and / or the light emitter is arranged as a linear light source, the light of the light emitter is parallel to the axial line of the barrel, and the barrel is made of a uniform light material.

4. The weld detection system of claim 2, wherein, The welding mark detection system further comprises a stroke sensor, which is used for detecting the rolling stroke of the barrel; and the host computer is used for enabling the first camera to acquire the first image according to the rolling stroke and a preset corresponding relationship.

5. The weld detection system of claim 2, wherein, The current collector tab is used for moving along the circumferential direction of the barrel, and the first camera comprises a line-scan camera, the line-scan line of the line-scan camera is parallel to the axial direction of the barrel.

6. The weld detection system of any one of claims 2 to 5, wherein, The welding mark detection system comprises at least two first cameras, which are arranged along the axial direction of the barrel; Along the transportation direction of the current collector tab, the two sides of the film area are respectively provided with the tab welding area, and the two first cameras are used for respectively acquiring images of the tab welding area and the adjacent through hole.

7. The weld detection system of any one of claims 2 to 5, wherein, The welding mark detection system further comprises a second camera, which is arranged at intervals with the first camera along the transportation direction of the current collector tab; The second camera is used for acquiring a second image from the front of the current collector tab, the second image at least comprising an image of the film area; The host computer is used for enabling the second camera to acquire the second image based on the back light roller irradiating the film area.

8. The weld detection system of claim 7, wherein, The current collector tab is used for being transported along the circumferential direction of the barrel, and the second camera and the first camera are arranged at intervals along the circumferential direction of the barrel; The barrel comprises a first light-transmitting area and a second light-transmitting area arranged along the circumferential direction of the barrel, the first light-transmitting area is used for being arranged opposite to the first camera, and the second light-transmitting area is used for being arranged opposite to the second camera.

9. A method of detecting a weld, characterized by, The welding mark detection method is used for detecting a current collecting tab of a lithium battery, the current collecting tab comprises a film area and a tab welding area, the film area is provided with a plurality of through holes, the tab welding area is provided with a welding mark structure, and the welding mark detection method comprises the following steps: Irradiating the tab welding area from the front surface of the current collecting tab so that the welding mark structure is bright and the tab welding area other than the welding mark structure is dark; Irradiating the film area from the back surface of the current collecting tab; Obtaining a first image from the front surface of the current collecting tab, the first image at least comprising an image of the welding mark structure and an image of the through hole.

10. The method of weld detection of claim 9, wherein, The step of obtaining the first image from the front surface of the current collecting tab comprises: Detecting the rolling stroke of a cylinder body used for abutting against the back surface of the current collecting tab; Obtaining the first image according to the rolling stroke and a preset corresponding relationship.

11. The method of weld detection of claim 9, wherein, The welding mark detection method further comprises the following steps: Providing at least two first cameras arranged along the axial direction of the cylinder body used for abutting against the back surface of the current collecting tab, and the film area is provided with the tab welding area on both sides along the transportation direction of the current collecting tab; The step of obtaining the first image from the front surface of the current collecting tab comprises: Respectively obtaining the image of the tab welding area and the adjacent through hole.

12. The method of weld detection according to any one of claims 9 to 11, wherein, The welding mark detection method further comprises the following steps: According to the first image, obtaining a first boundary line of the through hole, the first boundary line being towards the tab welding area; According to the first image, obtaining a second boundary line of the welding mark structure, the second boundary line being towards the film area; According to the first boundary line, the second boundary line and the image parameters corresponding to the first image, obtaining the distance from the welding mark structure to the first boundary line.

13. The method of weld detection of claim 12, wherein, The image parameters corresponding to the first image comprise pixel accuracy; According to the first boundary line, the second boundary line and the image parameters corresponding to the first image, obtaining the distance from the welding mark structure to the first boundary line comprises: According to the pixel accuracy, the number of pixels between the first boundary line and the second boundary line, obtaining the distance from the welding mark structure to the first boundary line.

14. The method of weld detection according to any one of claims 9 to 11, wherein, The welding mark detection method further comprises the following steps: According to the first image, obtaining a second boundary line and a third boundary line of the welding mark structure, the second boundary line being towards the film area, and the third boundary line being away from the film area; According to the second boundary line, the third boundary line and the image parameters corresponding to the first image, obtaining the distance between the second boundary line and the third boundary line.

15. The method of weld detection of claim 14, wherein, The image parameters corresponding to the first image comprise pixel accuracy; According to the second boundary line, the third boundary line and the image parameters corresponding to the first image, obtaining the distance between the second boundary line and the third boundary line comprises: According to the pixel accuracy, the number of pixels between the second boundary line and the third boundary line, obtaining the distance between the second boundary line and the third boundary line.

16. The method of weld detection according to any one of claims 9 to 11, wherein, The welding mark detection method further comprises the following steps: According to the first image and a first preset recognition model, obtaining the number of the welding mark structures.

17. The method of weld detection of claim 16, wherein, Before the step of obtaining the number of the welding mark structures according to the first image and the first preset recognition model, the welding mark detection method further comprises the following steps: obtaining at least one first training image from the front of the current collector sheet being irradiated, the first training image at least including images of the welding mark structures; numbering the welding mark structures in the first training image; forming the first preset recognition model according to the first training image after numbering.

18. The method of weld detection according to any one of claims 9 to 11, wherein, The welding mark detection method further comprises the following steps: obtaining a second image from the front of the current collector sheet based on the film area being irradiated, the second image at least including images of the film area.

19. The method of weld detection of claim 18, wherein, The welding mark detection method further comprises the following steps: obtaining the wrinkle or the tab from the second image according to the second image and a second preset recognition model.

20. A method of producing a current collector tab, characterized by, The current collector sheet production method comprises the following steps: preparing a current collector sheet of a lithium battery, the current collector sheet including a film area and a tab welding area, the film area being provided with a plurality of through holes, and the tab welding area being provided with welding mark structures; irradiating the tab welding area from the front of the current collector sheet for at least part of the prepared current collector sheets, so that the welding mark structures are bright and the tab welding area outside the welding mark structures is dark; irradiating the film area from the back of the current collector sheet; obtaining a first image from the front of the current collector sheet, the first image at least including images of the welding mark structures and the through holes.

21. The tab production method according to claim 20, wherein The step of preparing a current collector sheet of a lithium battery comprises: forming a plurality of arrayed through holes; forming a plurality of welding mark structures, and making the arrangement direction of the welding mark structures parallel to the arrangement direction of the through holes.

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