Battery piece mark point positioning method, silk-screen printing method and system

Abstract

The invention provides a battery piece mark point positioning method and a silk-screen printing method and system.The battery piece mark point positioning method comprises the steps that a contour camera and a plurality of overprinting cameras are calibrated and unified to a calibration coordinate system; determining contour feature parameters of the battery piece in a contour camera coordinate system based on a contour camera; and determining a first conversion relation between the contour camera coordinate system and the calibration coordinate system and a second conversion relation between the overprint camera coordinate system and the calibration coordinate system, and determining mark point coordinates of the plurality of mark points based on the first conversion relation, the second conversion relation, the distribution parameters of the plurality of mark points and the contour feature parameters. According to the invention, the positioning of the mark point can be realized based on the contour feature parameter, the first conversion relation, the second conversion relation and the distribution parameter obtained by the contour camera, the positioning precision of the coordinate of the mark point is ensured, the determination efficiency of the coordinate of the mark point is improved, and the positioning efficiency of the battery piece is further improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of screen printing in the photovoltaic industry, and particularly relates to a method for positioning marking points on a battery cell, a screen printing method, and a system. Background Art

[0002] In the screen printing technology of photovoltaic cells, non-offset printing is a key technology to improve printing quality. The prerequisite for determining whether printing is offset is to accurately determine the center position and deflection angle of the battery cell based on multiple marking points on the battery cell.

[0003] The prior art directly searches for all marking points in the full field of view and then determines the positions of the marking points. However, it has the following technical problems: The full field of view is much larger than the marking points on the battery cell. Directly performing fine positioning of the marking points in the full field of view is inefficient and time-consuming, and cannot meet the equipment production capacity requirements. If the resolution in the full field of view is reduced, the recognition accuracy of the marking points will decrease, resulting in a lower positioning accuracy of the battery cell and unable to meet the positioning accuracy requirements. Summary of the Invention

[0004] In view of this, it is necessary to provide a method for positioning marking points on a battery cell, a screen printing method, and a system to solve the technical problem in the prior art that it is impossible to balance positioning efficiency and positioning accuracy.

[0005] On the one hand, the present invention provides a method for determining the marking point coordinates of multiple marking points in a battery cell based on a contour camera and multiple overprint cameras; the method for positioning the marking points on the battery cell includes:

[0006] S101. Calibrate the contour camera and the multiple overprint cameras and unify them to a calibration coordinate system;

[0007] S102. Determine the contour feature parameters of the battery cell in the contour camera coordinate system based on the contour camera;

[0008] S103. Determine the first conversion relationship between the contour camera coordinate system and the calibration coordinate system and the second conversion relationship between the overprint camera coordinate system and the calibration coordinate system, obtain the distribution parameters of multiple marking points, and determine the marking point coordinates of the multiple marking points based on the first conversion relationship, the second conversion relationship, the distribution parameters of the multiple marking points, and the contour feature parameters.

[0009] In some possible implementation manners, in S103, determining the marking point coordinates of the multiple marking points based on the first conversion relationship, the second conversion relationship, the distribution parameters, and the feature parameters includes:

[0010] S201. Determine the calibration feature parameters of the cell in the calibration coordinate system based on the first conversion relationship and the profile feature parameters;

[0011] S202. Determine the rough coordinate values of the multiple marking points in the calibration coordinate system based on the calibration feature parameters and the distribution parameters;

[0012] S203. Determine the region of interest of the multiple marking points in the overprint camera coordinate system based on the rough coordinate values and the second conversion relationship;

[0013] S204. Determine the accurate coordinate values of the multiple marking points in the overprint camera coordinate system based on the region of interest;

[0014] S205. Determine the marking point coordinates of the multiple marking points in the calibration coordinate system based on the second conversion relationship and the accurate coordinate values.

[0015] In some possible implementation manners, the profile feature parameters include the profile center coordinates, and S102 includes:

[0016] S301. Obtain the profile image of the cell based on the profile camera, and determine the first corner point coordinates, the second corner point coordinates, the third corner point coordinates, and the fourth corner point coordinates of the cell in the profile camera coordinate system based on the profile image;

[0017] S302. Determine the profile center coordinates based on the first corner point coordinates, the second corner point coordinates, the third corner point coordinates, and the fourth corner point coordinates.

[0018] In some possible implementation manners, in S301, determining the first corner point coordinates, the second corner point coordinates, the third corner point coordinates, and the fourth corner point coordinates of the cell in the profile camera coordinate system based on the profile image includes:

[0019] S401. Determine the first profile edge, the second profile edge, the third profile edge, and the fourth profile edge of the cell based on the profile image;

[0020] S402. Determine the first corner point based on the first profile edge and the second profile edge, determine the second corner point based on the second profile edge and the third profile edge, determine the third corner point based on the third profile edge and the fourth profile edge, and determine the fourth corner point based on the fourth profile edge and the first profile edge;

[0021] S403. Determine the first corner point coordinates of the first corner point, the second corner point coordinates of the second corner point, the third corner point coordinates of the third corner point, and the fourth corner point coordinates of the fourth corner point based on the profile camera coordinate system.

[0022] In some possible implementations, S302 includes:

[0023] S501. Determine a first midpoint coordinate based on the first corner coordinate and the second corner coordinate;

[0024] S502. Determine a second midpoint coordinate based on the third corner coordinate and the fourth corner coordinate;

[0025] S503. Determine a third midpoint coordinate based on the first corner coordinate and the fourth corner coordinate;

[0026] S504. Determine a fourth midpoint coordinate based on the second corner coordinate and the third corner coordinate;

[0027] S505. Determine a first straight line based on the first midpoint coordinate and the second midpoint coordinate, and determine a second straight line based on the third midpoint coordinate and the fourth midpoint coordinate;

[0028] S506. Use the intersection coordinate of the first straight line and the second straight line as the contour center coordinate.

[0029] In some possible implementations, the multiple marking points include a first marking point, a second marking point, a third marking point, and a fourth marking point that enclose a rectangular contour;

[0030] The distribution parameter includes the width and height of the rectangular contour.

[0031] On the other hand, the present invention also provides a screen printing method, which is applied to a screen printing device. The screen printing device includes a movable printing platform and a UVW platform for adjusting the printing platform. The printing platform includes a loading position and a printing position. The loading position includes a contour camera and multiple overprint cameras. The screen printing method includes:

[0032] S801. Sequentially place multiple battery cells into the loading position, determine the marking point coordinates of each battery cell based on the positioning method of the battery cell marking points, and determine the center coordinate and deflection angle of the battery cell based on the marking point coordinates;

[0033] S802. Obtain the reference center coordinate and reference deflection angle of the printing screen zero position, determine the center coordinate difference based on the reference center coordinate and the center coordinate, and determine the deflection angle difference based on the deflection angle and the reference deflection angle;

[0034] S803. Rotate the printing platform to transfer the solar cell to the printing position, and send the central coordinate difference and the deflection angle difference to the UVW platform. The UVW platform adjusts the printing platform based on the central coordinate difference and the deflection angle difference. After the adjustment is completed, print the paste onto the solar cell;

[0035] Among them, the positioning method of the solar cell marking points is the positioning method of the solar cell marking points in any of the above possible implementation manners.

[0036] In some possible implementation manners, the printing platform further includes a blanking position, and the blanking position includes an AOI optical detection camera. The screen printing method further includes:

[0037] S901. Determine the target central coordinates and the target deflection angle of multiple solar cells based on the AOI optical detection camera;

[0038] S902. Determine the target central coordinate difference based on the central coordinates and the target central coordinates, and determine the target deflection angle difference based on the deflection angle and the target deflection angle;

[0039] S903. Determine the target deflection angle difference and the target central coordinate difference corresponding to the deflection angle difference;

[0040] S904. Obtain the rotation limit of the UVW platform, and determine multiple deflection angle adjustment intervals based on the rotation limit;

[0041] S905. Divide the deflection angle difference based on the deflection angle adjustment intervals, and determine the compensation average value of the target deflection angle difference and the target central coordinate difference within the deflection angle adjustment intervals;

[0042] S906. Compensate the next printing of the screen printing equipment based on the compensation average value.

[0043] In some possible implementation manners, S906 includes:

[0044] S1001. Obtain the next solar cell for the next printing, place the next solar cell into the loading position, and determine the solar cell central coordinates and the solar cell deflection angle of the next solar cell;

[0045] S1002. Obtain the reference central coordinates and the reference deflection angle of the printing screen zero position, determine the solar cell central coordinate difference based on the reference central coordinates and the solar cell central coordinates, and determine the solar cell deflection angle difference based on the solar cell deflection angle and the reference deflection angle;

[0046] S1003. Determine the target compensation average value for the next printing based on the difference in the deflection angle of the cell and the deflection angle adjustment range;

[0047] S1004. Rotate the printing platform to transfer the next cell to the printing position, and send the difference in the center coordinates of the cell, the difference in the deflection angle of the cell, and the target compensation average value to the UVW platform. The UVW platform adjusts the printing platform based on the difference in the center coordinates of the cell, the difference in the deflection angle of the cell, and the target compensation average value. After the adjustment is completed, print the paste onto the next cell to obtain the next cell with the printed paste.

[0048] On the other hand, the present invention also provides a positioning system for the marking points of a cell, which is used to determine the marking point coordinates of multiple marking points in the cell based on a contour camera and multiple overprint cameras; the positioning system for the marking points of the cell includes:

[0049] A coordinate calibration module, which is used to calibrate the contour camera and the multiple overprint cameras and unify them to a calibration coordinate system;

[0050] A contour feature parameter determination module, which is used to determine the contour feature parameters of the cell in the contour camera coordinate system based on the contour camera;

[0051] A marking point coordinate determination module, which is used to determine the first conversion relationship between the contour camera coordinate system and the calibration coordinate system and the second conversion relationship between the overprint camera coordinate system and the calibration coordinate system, obtain the distribution parameters of multiple marking points, and determine the marking point coordinates of the multiple marking points based on the first conversion relationship, the second conversion relationship, the distribution parameters of the multiple marking points, and the contour feature parameters.

[0052] On the other hand, the present invention also provides a screen printing system, which is applied to a screen printing device. The screen printing device includes a movable printing platform and a UVW platform for adjusting the printing platform. The printing platform includes a loading position and a printing position. The loading position includes a contour camera and multiple overprint cameras; the screen printing system includes:

[0053] A marking point positioning module, which is used to sequentially place multiple cells into the loading position, determine the marking point coordinates of each cell based on the positioning method of the cell marking points, and determine the center coordinates and deflection angle of the cell based on the marking point coordinates;

[0054] A difference determination module, which is used to obtain the reference center coordinates and reference deflection angle of the zero position of the printing stencil, and determine the difference in the center coordinates based on the reference center coordinates and the center coordinates, and determine the difference in the deflection angle based on the deflection angle and the reference deflection angle;

[0055] A printing module for rotating a printing platform to transfer a solar cell to a printing position, sending the difference in central coordinates and the difference in deflection angles to a UVW platform, and after the UVW platform adjusts the printing platform based on the difference in central coordinates and the difference in deflection angles, printing a paste onto the solar cell;

[0056] Wherein, the positioning method of the marking points on the solar cell is the positioning method of the marking points on the solar cell in any of the above possible implementation manners.

[0057] The beneficial effects of adopting the above implementation manner are as follows: The positioning method of the marking points on the solar cell provided by the present invention determines the contour feature parameters of the solar cell in the contour camera coordinate system based on a contour camera; determines the first conversion relationship between the contour camera coordinate system and the calibration coordinate system and the second conversion relationship between the overprint camera coordinate system and the calibration coordinate system, obtains the distribution parameters of multiple marking points, and determines the marking point coordinates of the multiple marking points based on the first conversion relationship, the second conversion relationship, the distribution parameters of the multiple marking points, and the contour feature parameters. It is not necessary to directly locate the marking points within a relatively large field of view, but the positioning of the marking points can be achieved based on the contour feature parameters, the first conversion relationship, the second conversion relationship, and the distribution parameters obtained by the contour camera. While ensuring the positioning accuracy of the marking point coordinates, the determination efficiency of the marking point coordinates is improved, and thus the positioning efficiency of the solar cell is improved. Description of the Drawings

[0058] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention, and those skilled in the art can also obtain other drawings without creative efforts based on these drawings.

[0059] Figure 1 It is a schematic flowchart of an embodiment of the positioning method of the marking points on the solar cell provided by the present invention;

[0060] Figure 2 For the present invention Figure 1 It is a schematic flowchart of an embodiment of S103 in the present invention;

[0061] Figure 3 For the present invention Figure 1 It is a schematic flowchart of an embodiment of S102 in the present invention;

[0062] Figure 4 For the present invention Figure 3 It is a schematic flowchart of an embodiment of S301 in the present invention;

[0063] Figure 5 For the present invention Figure 3 It is a schematic flowchart of an embodiment of S303 in the present invention;

[0064] Figure 6 Schematic structural diagram of an embodiment of the battery cell provided by the present invention;

[0065] Figure 7 Schematic structural diagram of an embodiment of the screen printing device provided by the present invention;

[0066] Figure 8 Schematic flow diagram of an embodiment of the screen printing method provided by the present invention;

[0067] Figure 9 Schematic flow diagram of an embodiment of compensating the screen printing process based on the compensation average value provided by the present invention;

[0068] Figure 10 For the present invention Figure 9 Schematic flow diagram of an embodiment of S906 in;

[0069] Figure 11 Schematic structural diagram of an embodiment of the positioning system of the marking points of the battery cell provided by the present invention;

[0070] Figure 12 Schematic structural diagram of an embodiment of the screen printing system provided by the present invention. Detailed implementation manners

[0071] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present invention.

[0072] It should be understood that the schematic drawings are not drawn to actual scale. The flowcharts used in the present invention illustrate the operations implemented according to some embodiments of the present invention. It should be understood that the operations in the flowcharts may not be implemented in sequence, and the steps without logical context relationships may be reversed or implemented simultaneously. In addition, those skilled in the art can add one or more other operations to the flowchart or remove one or more operations from the flowchart under the guidance of the content of the present invention. Some of the block diagrams shown in the drawings are functional entities, which do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software form, or implemented in one or more hardware modules or integrated circuits, or implemented in different networks and / or processor systems and / or microcontroller systems.

[0073] In the embodiments of the present invention, the descriptions such as "first" and "second" are only for descriptive purposes, and cannot be construed as indicating or implying their relative importance or implicitly specifying the quantity of the indicated technical features. Therefore, the technical features defined with "first" and "second" may explicitly or implicitly include at least one such feature.

[0074] Reference to "embodiment" herein means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the present invention. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0075] The prior art directly uses an overprint camera to search for a marking point within the full field of view of the overprint camera. However, the field of view of the overprint camera is much larger than the marking point, and it is impossible to quickly find the specific position of the marking point. It is necessary to perform a full-field search through some algorithm processing, which is extremely time-consuming. The present invention first gives a small region of interest within the full field of view of the overprint camera by using a contour camera, and searches within this region, which will greatly reduce the time.

[0076] Specifically, the present invention provides a method for positioning a marking point on a battery cell, a screen printing method, and a system, which will be described separately below.

[0077] Figure 1 FIG. is a schematic flowchart of an embodiment of the method for positioning a marking point on a battery cell provided by the present invention, which is used to determine the marking point coordinates of multiple marking points on the battery cell based on a contour camera and multiple overprint cameras; as Figure 1 shown, the method for positioning a marking point on a battery cell includes:

[0078] S101. Calibrate the contour camera and multiple overprint cameras and unify them to the calibration coordinate system;

[0079] S102. Determine the contour feature parameters of the battery cell in the contour camera coordinate system based on the contour camera;

[0080] S103. Determine the first conversion relationship between the contour camera coordinate system and the calibration coordinate system and the second conversion relationship between the overprint camera coordinate system and the calibration coordinate system, obtain the distribution parameters of multiple marking points, and determine the marking point coordinates of multiple marking points based on the first conversion relationship, the second conversion relationship, the distribution parameters of multiple marking points, and the contour feature parameters.

[0081] Compared with the prior art, the positioning method of the marking points of the battery cell provided by the embodiment of the present invention determines the contour feature parameters of the battery cell in the contour camera coordinate system based on the contour camera; determines the first conversion relationship between the contour camera coordinate system and the calibration coordinate system and the second conversion relationship between the overprint camera coordinate system and the calibration coordinate system, obtains the distribution parameters of multiple marking points, and determines the marking point coordinates of the multiple marking points based on the first conversion relationship, the second conversion relationship, the distribution parameters of the multiple marking points, and the contour feature parameters. Compared with the method of directly determining the marking point coordinates of multiple marking points under the overprint camera in the prior art, the embodiment of the present invention does not need to directly implement the positioning of the marking points within a relatively large visual field range, but can implement the positioning of the marking points based on the contour feature parameters, the first conversion relationship, the second conversion relationship, and the distribution parameters obtained by the contour camera. While ensuring the positioning accuracy of the marking point coordinates, the determination efficiency of the marking point coordinates is improved, and thus the positioning efficiency of the battery cell is improved.

[0082] Among them, step S101 is specifically: based on the calibration board, calibrate the contour camera and multiple overprint cameras and unify them to the calibration coordinate system. Specifically: the contour camera and each overprint camera sequentially photograph the calibration board to obtain the first coordinates of the feature points on the calibration board in the contour camera coordinate system and the second coordinates in the overprint camera coordinate system, obtain the reference coordinates of the feature points on the calibration board in the calibration coordinate system, and calibrate the contour camera and multiple overprint cameras based on the reference coordinates, the first coordinates, and the second coordinates.

[0083] Among them, the calibration coordinate system is a three-dimensional space coordinate system with a point at a specified position on the calibration board as the origin.

[0084] Among them, the specific process of calibrating the contour camera and multiple overprint cameras based on the reference coordinates, the first coordinates, and the second coordinates may be: determining the first conversion relationship between the contour camera coordinate system and the calibration coordinate system based on the reference coordinates and the first coordinates, and determining the second conversion relationship between the overprint camera coordinate system and the calibration coordinate system based on the reference coordinates and the second coordinates.

[0085] Among them, step S102, determining the contour feature parameters of the battery cell in the contour camera coordinate system based on the contour camera, is specifically to photograph the image of the battery cell by the contour camera, thereby obtaining the contour feature parameters.

[0086] In a specific embodiment of the present invention, the contour feature parameters can be of various types (the word "contour" is only used to indicate that this feature parameter was initially captured by a contour camera and is a parameter in the contour camera coordinate system). For example, the coordinates of a certain corner point of the battery cell, or the center coordinates of the battery cell. It should be noted that the contour feature actually refers to the reference feature used when making marking points on the battery cell. When the reference feature is a certain corner point on the battery cell, such as the upper left corner point of the battery cell, then multiple marking points are all made with reference to the upper left corner point; when the reference feature is the center point of the battery cell, then multiple marking points are all made with reference to the center point of the battery cell.

[0087] In step S103, it is also necessary to obtain the distribution parameters of the marking points in order to accurately and quickly determine the marking point coordinates of multiple marking points on the battery cell. In a specific embodiment of the present invention, the distribution parameters of the marking points are used to reflect the relative positions of multiple marking points relative to the contour feature. For example, when the number of marking points is four and the four marking points enclose a rectangular contour, when the reference feature is the center point of the battery cell, the distribution parameters can be the width and height of the rectangular contour. At this time, the center of the rectangular contour is the center of the battery cell. After knowing the center of the battery cell and the width and height of the rectangular contour, the positions of the four marking points can be deduced; when the contour feature is the upper left corner point on the battery cell, then the distribution parameters can be the horizontal and vertical distances of the four marking points relative to the upper left corner point. After knowing the horizontal and vertical distances of the four marking points relative to the upper left corner point and the position of the upper left corner point, the positions of the four marking points can be deduced.

[0088] That is to say, the contour feature parameters can be the contour center coordinates, or the feature point coordinates of any feature point other than the center point set in advance. When the contour feature parameters are the contour center coordinates, the distribution parameters are the distribution parameters between the marking points and the contour center coordinates. When the contour feature parameters are the feature point coordinates, the distribution parameters are the distribution parameters between the marking points and the feature point coordinates. By setting the contour feature parameters as the contour center coordinates or the feature point coordinates, the diversity of the feature parameters can be improved, avoiding the technical problem that when printing on the battery cell, the marking points cannot be effectively located due to the paste covering the feature parameters on the battery cell, and improving the reliability of locating the marking points.

[0089] For the present invention, as a more specific embodiment, it is described by taking an example where there are 4 marking points on the battery cell, the 4 marking points enclose a rectangular contour, and the contour feature is the center of the battery cell. Among them, the number of overprint cameras is also 4. The contour camera and the 4 overprint cameras are arranged at the battery cell loading station. When the battery cell is at the loading station, the contour camera is located above the vicinity of the center of the battery cell, and the four overprint cameras are located above the four corners of the battery cell. Generally, the 4 marking points are roughly made at the four corner points of a rectangle centered on the battery cell.

[0090] In some embodiments of the present invention, as Figure 2 shown, step S103 includes:

[0091] S201. Determine the calibration feature parameters of the battery cell in the calibration coordinate system based on the first conversion relationship and the contour feature parameters;

[0092] S202. Determine the rough coordinate values of multiple marking points in the calibration coordinate system based on the calibration feature parameters and the distribution parameters;

[0093] S203. Determine the regions of interest of multiple marking points in the overprint camera coordinate system based on the rough coordinate values and the second conversion relationship;

[0094] S204. Determine the exact coordinate values of multiple marking points in the overprint camera coordinate system based on the regions of interest;

[0095] S205. Determine the marking point coordinates of multiple marking points in the calibration coordinate system based on the second conversion relationship and the exact coordinate values.

[0096] In the embodiments of the present invention, the rough coordinate values of multiple marking points in the calibration coordinate system are determined based on the calibration feature parameters and the distribution parameters. Then, based on the rough coordinate values and the second conversion relationship, the regions of interest of multiple marking points in the overprint camera coordinate system are determined. Based on the regions of interest, the exact coordinate values of multiple marking points in the overprint camera coordinate system are determined, without the need for the overprint camera to identify the marking points within the full field of view, improving the positioning efficiency of the marking point coordinates. By searching for and precisely positioning the marking points in the region of interest (a region smaller than the field of view of the overprint camera), the search time can be reduced by dozens of times.

[0097] It should be understood that: the regions of interest are located within the field of view of each overprint camera.

[0098] For the convenience of detailed description of the positioning method of the marking points below, taking the contour feature parameter as the center coordinates of the cell contour as an example for detailed description. Regarding step S201, specifically, the center coordinates of the contour include the horizontal coordinate of the center of the contour and the vertical coordinate of the center of the contour in the contour camera coordinate system, and the calibration feature parameters include the horizontal coordinate of the calibration center and the vertical coordinate of the calibration center in the calibration coordinate system. Then, the conversion relationship between the contour feature parameters and the calibration feature parameters is as follows:

[0099]

[0100] In the formula, O X is the horizontal coordinate of the center of the contour; O Y is the vertical coordinate of the center of the contour; O X ' is the horizontal coordinate of the calibration center; O Y ' is the vertical coordinate of the calibration center; M 0 is the first conversion relationship. Thus, based on the first conversion relationship M 0 and the contour feature parameters O X and O Y to determine the calibration feature parameters O X ' and O Y ' in the calibration coordinate system.

[0101] More specifically, for step S202, taking multiple marking points including the first marking point, the second marking point, the third marking point, and the fourth marking point that enclose a rectangular contour as an example, the distribution parameters include the width W and height H of the rectangular contour (it should be noted that: the multiple marking points may also include multiple marking points that enclose a circular contour, and the distribution parameter is the radius of the circular contour. The method for determining the coordinates of each marking point is not specifically limited here). According to the calibration feature parameters O X ' and O Y ' in the calibration coordinate system and the distribution parameters width W and height H, determine the rough coordinate values of the four marking points in the calibration coordinate system:

[0102] X A = O' X - W / 2

[0103] Y A = O' Y - H / 2

[0104] X B = O' X + W / 2

[0105] Y B = O' Y - H / 2

[0106] X C = O' X + W / 2

[0107] Y C = O' Y + H / 2

[0108] X D = O' X - W / 2

[0109] Y D = O' Y + H / 2

[0110] X' A = (X A - O' X ) * cosα - (Y A - O' Y ) * sinα + O' X

[0111] Y' A = (X A - O' X ) * sinα + (Y A - O' Y ) * cosα + O' Y

[0112] X' B = (X B - O' X ) * cosα - (Y B - O' Y ) * sinα + O' X

[0113] Y' B = (X B - O' X ) * sinα + (Y B - O' Y ) * cosα + O' Y

[0114] X' C = (X C - O' X ) * cosα - (Y C - O' Y ) * sinα + O' X

[0115] Y' C = (X C - O' X ) * sinα + (Y C - O' Y ) * cosα + O' Y

[0116] X' D = (X D - O') X ) * cosα - (Y D - O') Y ) * sinα + O' X

[0117] Y' D = (X D - O') X ) * sinα + (Y D - O') Y ) * cosα + O' Y

[0118] In the formula, (X A , Y A ), (X B , Y B ), (X C , Y C ), (X D , Y D ) are the rough coordinate values of the first marking point, the second marking point, the third marking point, and the fourth marking point in the calibration coordinate system without considering the deflection angle of the cell. (X' A , Y' A ), (X' B , Y' B ), (X' C , Y' C ), (X' D , Y' D ) are the rough coordinate values of the first marking point, the second marking point, the third marking point, and the fourth marking point in the calibration coordinate system considering the deflection angle of the cell, respectively.

[0119] Among them, the deflection angle of the cell refers to the deflection angle of the cell in the calibration coordinate system.

[0120] It should be noted that when the cell is loaded, there may be a deflection angle relative to the calibration coordinate system. Therefore, when determining the contour feature parameters of the cell in the contour camera coordinate system based on the contour camera, the rough deflection angle of the incoming material in the calibration plate coordinate system will also be calculated. One of the methods for determining the rough deflection angle is:

[0121] Calculate the angle Angle1 of the straight line AB in the calibration plate coordinate system, calculate the angle Angle2 of the straight line CD in the calibration plate coordinate system, and finally obtain the deflection angle α of the incoming material in the calibration plate coordinate system as α = (Angle1 + Angle2) / 2.

[0122] When there is no rough deflection angle of the incoming material in the calibration plate coordinate system, it need not be considered.

[0123] It should be noted that: The specific process of determining the region of interest in step S203 is as follows: Based on the rough coordinate values and the second conversion relationship, determine the superimposed coordinate values of each marked point in the superimposed camera coordinate system. For example, when the solar cell includes a first marked point, a second marked point, a third marked point, and a fourth marked point, the superimposed coordinate values of each marked point in the corresponding superimposed camera are obtained through four superimposed cameras respectively, and then the region of interest of each superimposed camera is determined based on the superimposed coordinate values.

[0124] More specifically, at this time, the rough coordinate values of multiple marked points in the calibration coordinate system have been obtained. Since it is assumed that there are 4 marked points for example, the rough coordinate values at this time include a first rough coordinate value, a second rough coordinate value, a third rough coordinate value, and a fourth rough coordinate value. The second conversion relationship includes a first sub-conversion relationship between the superimposed camera coordinate system of the first superimposed camera and the calibration coordinate system, a second sub-conversion relationship between the superimposed camera coordinate system of the second superimposed camera and the calibration coordinate system, a third sub-conversion relationship between the superimposed camera coordinate system of the third superimposed camera and the calibration coordinate system, and a fourth sub-conversion relationship between the superimposed camera coordinate system of the fourth superimposed camera and the calibration coordinate system. The superimposed coordinate values include a first superimposed coordinate value, a second superimposed coordinate value, a third superimposed coordinate value, and a fourth superimposed coordinate value that correspond one-to-one to the first marked point, the second marked point, the third marked point, and the fourth marked point respectively. Their expressions are as follows:

[0125]

[0126]

[0127]

[0128]

[0129] In the formula, M A ' is the first sub-conversion relationship, M B ' is the second sub-conversion relationship, M C ' is the third sub-conversion relationship, M' D is the fourth sub-conversion relationship, (X' A , Y' A ) is the first rough coordinate value, (X' B , Y' B ) is the second rough coordinate value, (X' C , Y' C ) is the third rough coordinate value, (X' D , Y' D ) is the fourth rough coordinate value; (X TA , Y TA ) is the first superimposed coordinate value; (X TB , YTB ), which is the second overprint coordinate value, (X TC , Y TC ), which is the third overprint coordinate value, (X TD , Y TD ), which is the fourth overprint coordinate value.

[0130] Next, based on each overprint coordinate value, the region of interest of each overprint camera is determined. Here, the region of interest refers to the region within a preset range centered on the overprint coordinate value. The preset range can be determined according to the size of the outer contour of the marking point. For example, it is a region that is 2 - 5 times the area of the outer contour of the marking point.

[0131] Furthermore, step S204 is specifically as follows: Based on the region of interest, the exact coordinate values of multiple marking points in the overprint camera coordinate system are determined. The overprint camera searches and precisely locates the marking points within this region of interest, and uses targeted positioning algorithms according to the characteristics of the marking points such as shape, color, and contour. Such as template matching positioning, Blob feature analysis positioning, etc. At this time, the exact coordinate values of the marking points in the overprint camera coordinate system can be calculated.

[0132] Furthermore, in step S205, based on the second conversion relationship and the exact coordinate values, the exact coordinate values in the overprint camera coordinate system are converted to the calibration coordinate system, thereby determining the marking point coordinates of multiple marking points in the calibration coordinate system. The coordinates of the first marking point, the second marking point, the third marking point, and the fourth marking point in the calibration coordinate system are respectively (X a , Y a ), (X b , Y b ), (X c , Y c ), (X d , Y d ).

[0133] In some other embodiments of the present invention, S103 may also be:

[0134] Based on the contour feature parameters and distribution parameters, the rough contour coordinate values of multiple marking points in the contour camera coordinate system are determined, and then based on the first conversion relationship and the rough contour coordinate values, the rough coordinate values of multiple marking points in the calibration coordinate system are determined; based on the rough coordinate values and the second conversion relationship, the regions of interest of multiple overprint cameras are determined; based on multiple overprint cameras, the images of interest in the regions of interest are obtained, and based on the images of interest, the exact coordinate values of multiple marking points in the overprint camera coordinate system are determined; based on the second conversion relationship and the exact coordinate values, the marking point coordinates of multiple marking points in the calibration coordinate system are determined.

[0135] The difference between the above process and steps S201 - S205 is that first, based on the distribution parameters, the rough contour coordinate values of multiple marker points in the contour camera coordinate system are determined, and then based on the first conversion relationship, the rough coordinate values of the multiple marker points in the calibration coordinate system are determined.

[0136] When the contour feature parameter is the contour center coordinate, in some embodiments of the present invention, such as Figure 3 shown, S102 includes:

[0137] S301. Obtain the contour image of the battery cell based on the contour camera, and determine the first corner point coordinate, the second corner point coordinate, the third corner point coordinate, and the fourth corner point coordinate of the battery cell in the contour camera coordinate system;

[0138] S302. Determine the contour center coordinate based on the first corner point coordinate, the second corner point coordinate, the third corner point coordinate, and the fourth corner point coordinate.

[0139] In some embodiments of the present invention, such as Figure 4 shown, S301 includes:

[0140] S401. Determine the first contour edge, the second contour edge, the third contour edge, and the fourth contour edge of the battery cell based on the contour image;

[0141] S402. Determine the first corner point based on the first contour edge and the second contour edge, determine the second corner point based on the second contour edge and the third contour edge, determine the third corner point based on the third contour edge and the fourth contour edge, and determine the fourth corner point based on the fourth contour edge and the first contour edge;

[0142] S403. Determine the first corner point coordinate of the first corner point, the second corner point coordinate of the second corner point, the third corner point coordinate of the third corner point, and the fourth corner point coordinate of the fourth corner point based on the contour camera coordinate system.

[0143] In some embodiments of the present invention, such as Figure 5 shown, S302 includes:

[0144] S501. Determine the first midpoint coordinate based on the first corner point coordinate and the second corner point coordinate;

[0145] S502. Determine the second midpoint coordinate based on the third corner point coordinate and the fourth corner point coordinate;

[0146] S503. Determine the third midpoint coordinate based on the first corner point coordinate and the fourth corner point coordinate;

[0147] S504. Determine the fourth midpoint coordinate based on the second corner point coordinate and the third corner point coordinate;

[0148] S505. Determine the first straight line based on the first midpoint coordinate and the second midpoint coordinate, and determine the second straight line based on the third midpoint coordinate and the fourth midpoint coordinate;

[0149] S506. Use the intersection coordinate of the first straight line and the second straight line as the contour center coordinate.

[0150] In a specific embodiment of the present invention, as Figure 6 shown, L1 is the first contour edge, L2 is the second contour edge, L3 is the third contour edge, L4 is the fourth contour edge. From the intersection points of each contour edge, the first corner point A, the second corner point B, the third corner point C, and the fourth corner point D can be determined.

[0151] Furthermore, since in the screen printing technology in the photovoltaic industry, more attention is paid to whether there is a printing offset problem. Therefore, on the premise of proposing the positioning method of the cell marking points, the present invention also provides a screen printing method, which is applied to a screen printing device. As Figure 7 shown, the screen printing device 10 includes a printing platform 11 and a UVW platform (not shown in the figure) for adjusting the printing platform 11. The printing platform 11 includes a loading position and a printing position. The loading position includes a contour camera 111 and a plurality of overprint cameras 112. Then, as Figure 8 shown, the screen printing method includes:

[0152] S801. Sequentially place a plurality of cells into the loading position, determine the marking point coordinates of each cell based on the positioning method of the cell marking points, and determine the center coordinate and deflection angle of the cell based on the marking point coordinates;

[0153] S802. Obtain the reference center coordinate and reference deflection angle of the printing screen zero position, determine the center coordinate difference based on the reference center coordinate and the center coordinate, and determine the deflection angle difference based on the deflection angle and the reference deflection angle;

[0154] S803. Rotate the printing platform 11, transfer the cell to the printing position, and send the center coordinate difference and the deflection angle difference to the UVW platform. The UVW platform adjusts the printing platform 11 based on the center coordinate difference and the deflection angle difference. After the adjustment is completed, print the paste onto the cell;

[0155] Wherein, the positioning method of the cell marking points is the positioning method of the cell marking points in any of the above embodiments.

[0156] Wherein, the printing screen zero position refers to the position of the screen on the UVW platform after the UVW platform is reset (each axis of the UVW platform is at zero position). At this time, the position of the screen on the UVW platform is the printing screen zero position.

[0157] Wherein, the reference deflection angle of the printing screen zero position refers to the deflection angle of the printing screen in the calibrated coordinate system when the printing screen is at the zero position.

[0158] In a specific embodiment of the present invention, the marker coordinates of the first marker point, the second marker point, the third marker point, and the fourth marker point determined in step S801 are respectively (X a , Y a ), (X b , Y b ), (X c , Y c ), (X d , Y d ), then the center coordinates (C X , C Y ) are:

[0159] C X = (X a + X b + X c + X d ) / 4

[0160] C Y = (Y a + Y b + Y c + Y d ) / 4

[0161] The deflection angle is:

[0162] A = (A up + A bottom ) / 2

[0163] A up = arctan((Y c - Y b ) / (X c - X b ) * 180 / Π

[0164] A bottom = arctan((Y d - Y a ) / (X d - X a ) * 180 / Π

[0165] If the reference center coordinates in step S802 are (C mX , C mY ), and the reference deflection angle is A m , then the amount that the UVW platform needs to move is:

[0166] ΔC mX = C X - C mX

[0167] ΔC mY = CY -C mY

[0168] ΔA m = A - A m

[0169] In the formula, ΔC mX is the amount of movement of the UVW platform along the X-axis in the calibrated coordinate system, and ΔC mY is the amount of movement of the UVW platform along the X-axis in the calibrated coordinate system, and ΔA m is the angle of rotation of the UVW platform.

[0170] Among them, ΔA m ranges from ±3°.

[0171] Furthermore, during the printing process of the battery cell, a certain pressure needs to be applied with a squeegee to the paste part of the screen, and at the same time, it moves towards the other end of the screen. The paste is squeezed from the mesh holes of the graphic part onto the battery substrate during the movement to form the required graphic, and then the battery cell is printed. Due to reasons such as uneven printing pressure or loose screen plate, there will be a technical problem that even if the printing platform is adjusted in step S803, printing deviation still occurs. To solve this technical problem, in some embodiments of the present invention, as Figure 7 shown, the printing platform further includes a blanking position, and the blanking position includes an AOI optical inspection camera. Then, as Figure 9 shown, the screen printing method further includes:

[0172] S901. Determine the target center coordinates and target deflection angles of multiple battery cells based on the AOI optical inspection camera 113;

[0173] S902. Determine the target center coordinate difference based on the center coordinates and the target center coordinates, and determine the target deflection angle difference based on the deflection angle and the target deflection angle;

[0174] S903. Determine the target deflection angle difference and target center coordinate difference corresponding to the deflection angle difference; that is, record the deflection angle difference ΔA m after loading a battery cell, and the target deflection angle difference and target center coordinate difference (△X, △Y, △A) corresponding to ΔA m obtained by the AOI optical inspection camera 113 after the battery cell is printed and moves to the printing position;

[0175] S904. Obtain the rotation limit of the UVW platform, and determine multiple deflection angle adjustment intervals based on the rotation limit;

[0176] S905, based on the deflection angle adjustment interval, the deflection angle difference is divided, and the compensation average value of the target deflection angle difference and the target center coordinate difference (△X, △Y, △A) within the deflection angle adjustment interval is determined (the average values ​​of △X, △Y, and △A are calculated N times, respectively);

[0177] S906 , compensating the next printing of the screen printing device based on the compensation average value.

[0178] Calculate the ΔA of each battery cell m , and record the target center coordinate difference and target deflection angle difference (△X, △Y, △A) at each time. It is known that the rotation limit of the UVW platform is ±3°. Divide ±3° into six parts, namely (-3°, -2°)(-2°, -1°)(-1°, 0°)(0°, 1°)(1°, 2°)(2°, 3°). Summarize the recorded differences (△X, △Y, △A) into the corresponding interval according to the value of △Am.

[0179] Set the number of updates N, that is, every N times, the average value of the above six intervals is counted and saved. When the material is loaded again, the saved six interval differences are loaded and the ΔA of the material is calculated. m Perform corresponding interval compensation.

[0180] Specifically,

[0181] ΔX=X m -C x

[0182] ΔY=Y m -C Y

[0183] ΔA=A m -A

[0184] Where ΔX is the target center horizontal coordinate difference; ΔY is the target center vertical coordinate difference; ΔA is the target deflection angle difference; X m Y is the horizontal coordinate of the target center; m is the vertical coordinate of the target center, A m is the target deflection angle, C x is the central horizontal axis, C Y is the center ordinate, and A is the deflection angle.

[0185] The embodiment of the present invention sends the compensation average value to the UVW platform, and the UVW platform adjusts the printing platform based on the center coordinate difference and the deflection angle difference, which can further ensure the printing yield of the battery cell.

[0186] Further, in the embodiments of the present invention, instead of making an adjustment every time a battery cell is produced, after the deviation between the target center coordinates and the target deflection angle obtained by comparing the AOI optical detection camera and the center coordinates and the deflection angle obtained by the loading position camera is greater than the allowable range, data after the printing of the battery cells is collected for a period of time (the reason for collecting for a period of time is that there may be no deviation after printing several pieces). Based on the interval division of the reference deflection angle difference, the compensation average value of each deflection angle adjustment interval is determined, and then the compensation average value is used for segmented compensation of the next printing, so that the system will automatically perform corresponding printing data compensation to prevent losses caused by large-scale printing offset. Further, since the present application determines the supplementary average value of each deflection angle adjustment interval, the randomness and instability of the compensation are eliminated, the stability and rationality of the compensation are improved, and further the printing yield of the battery cells is improved.

[0187] It should be understood that as the number of printings increases, the compensation average value can be updated according to the results obtained from each printing.

[0188] It should be noted that multiple Mark points (such as holes penetrating the screen plate) are also made on the printing screen plate itself. After screen printing is completed at the printing position, the paste on the printing screen plate will be printed onto the battery cell through the Mark points, that is, there will also be paste at the position of the battery cell corresponding to the screen plate Mark points. This facilitates the AOI optical detection camera to capture the paste at the position of the corresponding screen plate Mark points when the battery cell moves from the printing position to the unloading position, so as to obtain the target center coordinates and the target deflection angle of the battery cell.

[0189] Among them, when the number of screen plate Mark points is also 4, the specific process of the target center coordinates and the target deflection angle can refer to the process of determining the rough coordinate values and the rough deflection angle of the four marking points in the calibration coordinate system in the above embodiments, and will not be specifically described here.

[0190] In some embodiments of the present invention, as Figure 10 shown, step S906 includes:

[0191] S1001. Obtain the next battery cell for the next printing, place the next battery cell at the loading position, and determine the battery cell center coordinates and the battery cell deflection angle of the next battery cell;

[0192] S1002. Obtain the reference center coordinates and the reference deflection angle of the zero position of the printing screen plate, determine the battery cell center coordinate difference based on the reference center coordinates and the battery cell center coordinates, and determine the battery cell deflection angle difference based on the battery cell deflection angle and the reference deflection angle;

[0193] S1003. Determine the target compensation average value for the next printing based on the difference in the deflection angle of the battery cell and the deflection angle adjustment range; where the target compensation average value is the actual compensation average value to be adjusted obtained from the compensation average values of each previously obtained deflection angle adjustment range based on the difference in the deflection angle of the current battery cell.

[0194] S1004. Rotate the printing platform to transfer the next battery cell to the printing position, and send the difference in the center coordinates of the battery cell, the difference in the deflection angle of the battery cell, and the target compensation average value to the UVW platform. The UVW platform adjusts the printing platform based on the difference in the center coordinates of the battery cell, the difference in the deflection angle of the battery cell, and the target compensation average value. After the adjustment is completed, print the paste onto the next battery cell to obtain the next battery cell with the printed paste.

[0195] During the next printing process, the difference in the center coordinates of the battery substrate, the difference in the deflection angle of the battery substrate, and the target compensation average value are considered simultaneously, improving the comprehensiveness and rationality of adjusting the printing platform.

[0196] It should be noted that: after printing is completed, it is also possible to determine whether the next battery cell meets the requirements based on the AOI optical detection camera. If it meets the requirements, the printing is completed. Among them, the requirements specifically mean that no abnormal situations such as broken pieces or damage occur.

[0197] In summary, the screen printing method provided by the embodiments of the present invention can quickly locate the marking points of the battery substrate without loss of pixel accuracy, and then quickly determine the center coordinates and deflection angle of the battery substrate, shortening the positioning time to 1 / 20 of the traditional positioning time, improving the efficiency and yield of screen printing.

[0198] Furthermore, by correcting the deviation of the printing platform, it is possible to real-time identify whether the battery cells formed by printing meet the functional requirements, and perform segmented regular deviation correction through data statistics, which can avoid large-scale printing deviation and reduce the printing failure rate.

[0199] The screen printing machine with an automatic deviation correction function can achieve full-automatic calibration during mesh replacement and timing, and no manual intervention is required later.

[0200] In order to better implement the positioning method of the marking points of the battery cell in the embodiments of the present invention, correspondingly, based on the positioning method of the marking points of the battery cell, as Figure 11 shown, the embodiments of the present invention further provide a positioning system for the marking points of the battery cell, which is used to determine the marking point coordinates of multiple marking points in the battery cell based on a contour camera and multiple overprint cameras; the positioning system 1100 for the marking points of the battery cell includes:

[0201] A coordinate calibration module 1101, which is used to calibrate the contour camera and multiple overprint cameras and unify them to the calibration coordinate system;

[0202] The contour feature parameter determination module 1102 is configured to determine the contour feature parameters of the battery cell in the contour camera coordinate system based on the contour camera;

[0203] The marker point coordinate determination module 1103 is configured to determine the first conversion relationship between the contour camera coordinate system and the calibration coordinate system and the second conversion relationship between the overprint camera coordinate system and the calibration coordinate system, obtain the distribution parameters of multiple marker points, and determine the marker point coordinates of the multiple marker points based on the first conversion relationship, the second conversion relationship, the distribution parameters of the multiple marker points, and the contour feature parameters.

[0204] The positioning system 1100 for the battery cell marker points provided in the above embodiments can implement the technical solutions described in the above embodiments of the positioning method for the battery cell marker points. The specific implementation principles of the above modules or units can be referred to the corresponding content in the above embodiments of the positioning method for the battery cell marker points, which will not be elaborated here.

[0205] To better implement the screen printing method in the embodiments of the present invention, correspondingly, on the basis of the screen printing method, as Figure 12 shown, the embodiments of the present invention further provide a screen printing system, which is applied to a screen printing device. The screen printing device includes a movable printing platform and a UVW platform for adjusting the printing platform. The printing platform includes a loading position and a printing position. The loading position includes a contour camera and multiple overprint cameras; the screen printing system 1200 includes:

[0206] The marker point positioning module 1201 is configured to sequentially place multiple battery cells into the loading position, determine the marker point coordinates of each battery cell based on the positioning method for the battery cell marker points, and determine the center coordinates and deflection angles of the battery cells based on the marker point coordinates;

[0207] The difference determination module 1202 is configured to obtain the reference center coordinates and reference deflection angles of the zero position of the printing screen plate, determine the center coordinate difference based on the reference center coordinates and the center coordinates, and determine the deflection angle difference based on the deflection angle and the reference deflection angle;

[0208] The printing module 1203 is configured to rotate the printing platform, transfer the battery cell to the printing position, and send the center coordinate difference and the deflection angle difference to the UVW platform. The UVW platform adjusts the printing platform based on the center coordinate difference and the deflection angle difference. After the adjustment is completed, print the paste onto the battery cell;

[0209] Wherein, the positioning method for the battery cell marker points is the positioning method for the battery cell marker points in any one of the above embodiments.

[0210] The screen printing system 1200 provided in the above embodiments can implement the technical solutions described in the above embodiments of the screen printing method. For the specific implementation principles of the above modules or units, reference can be made to the corresponding content in the above embodiments of the screen printing method, which will not be elaborated here.

[0211] Those skilled in the art can understand that all or part of the processes for implementing the methods in the above embodiments can be completed by instructing relevant hardware (such as a processor, a controller, etc.) through a computer program, and the computer program can be stored in a computer-readable storage medium. Among them, the computer-readable storage medium is a magnetic disk, an optical disk, a read-only memory, or a random access memory, etc.

[0212] The above has introduced in detail the positioning method, screen printing method and system of the battery cell marking points provided by the present invention. Specific examples are used in this article to elaborate on the principles and implementation manners of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those skilled in the art, according to the idea of the present invention, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A positioning method for marking points on a solar cell, characterized in that, it is used to determine the marking point coordinates of multiple marking points on a solar cell based on a contour camera and multiple overprint cameras; the positioning method for the marking points on the solar cell includes: S101. Calibrate the contour camera and the multiple overprint cameras and unify them to a calibration coordinate system; S102. Determine the contour feature parameters of the solar cell in the contour camera coordinate system based on the contour camera; S103. Determine the first conversion relationship between the contour camera coordinate system and the calibration coordinate system and the second conversion relationship between the overprint camera coordinate system and the calibration coordinate system, obtain the distribution parameters of multiple marking points, and determine the marking point coordinates of the multiple marking points based on the first conversion relationship, the second conversion relationship, the distribution parameters of the multiple marking points, and the contour feature parameters.

2. The positioning method for marking points on a solar cell according to claim 1, characterized in that, determining the marking point coordinates of the multiple marking points based on the first conversion relationship, the second conversion relationship, the distribution parameters, and the feature parameters in S103 includes: S201. Determine the calibration feature parameters of the solar cell in the calibration coordinate system based on the first conversion relationship and the contour feature parameters; S202. Determine the rough coordinate values of the multiple marking points in the calibration coordinate system based on the calibration feature parameters and the distribution parameters; S203. Determine the region of interest of the multiple marking points in the overprint camera coordinate system based on the rough coordinate values and the second conversion relationship; S204. Determine the accurate coordinate values of the multiple marking points in the overprint camera coordinate system based on the region of interest; S205. Determine the marking point coordinates of the multiple marking points in the calibration coordinate system based on the second conversion relationship and the accurate coordinate values.

3. The positioning method for marking points on a solar cell according to claim 2, characterized in that, the contour feature parameters include the contour center coordinates, then S102 includes: S301. Obtain the contour image of the solar cell based on the contour camera, and determine the first corner point coordinate, the second corner point coordinate, the third corner point coordinate, and the fourth corner point coordinate of the solar cell in the contour camera coordinate system based on the contour image; S302. Determine the contour center coordinates based on the first corner point coordinate, the second corner point coordinate, the third corner point coordinate, and the fourth corner point coordinate.

4. The positioning method for marking points on a solar cell according to claim 3, characterized in that, determining the first corner point coordinate, the second corner point coordinate, the third corner point coordinate, and the fourth corner point coordinate of the solar cell in the contour camera coordinate system based on the contour image in S301 includes: S401. Determine the first contour edge, the second contour edge, the third contour edge, and the fourth contour edge of the solar cell based on the contour image; S402. Determine the first corner point based on the first contour edge and the second contour edge, determine the second corner point based on the second contour edge and the third contour edge, determine the third corner point based on the third contour edge and the fourth contour edge, and determine the fourth corner point based on the fourth contour edge and the first contour edge; S403. Determine the first corner point coordinate of the first corner point, the second corner point coordinate of the second corner point, the third corner point coordinate of the third corner point, and the fourth corner point coordinate of the fourth corner point based on the contour camera coordinate system.

5. The positioning method of the battery cell marking points according to claim 3, characterized in that, S302 includes: S501. Determine the first midpoint coordinate based on the first corner point coordinate and the second corner point coordinate; S502. Determine the second midpoint coordinate based on the third corner point coordinate and the fourth corner point coordinate; S503. Determine the third midpoint coordinate based on the first corner point coordinate and the fourth corner point coordinate; S504. Determine the fourth midpoint coordinate based on the second corner point coordinate and the third corner point coordinate; S505. Determine the first straight line based on the first midpoint coordinate and the second midpoint coordinate, and determine the second straight line based on the third midpoint coordinate and the fourth midpoint coordinate; S506. Take the intersection coordinate of the first straight line and the second straight line as the contour center coordinate.

6. The positioning method of the battery cell marking points according to claim 1, characterized in that, the multiple marking points include a first marking point, a second marking point, a third marking point, and a fourth marking point that enclose a rectangular contour; the distribution parameter includes the width and height of the rectangular contour.

7. A screen printing method, characterized in that, applied to a screen printing device, the screen printing device includes a movable printing platform and a UVW platform for adjusting the printing platform, the printing platform includes a loading position and a printing position, and the loading position includes a contour camera and a plurality of overprint cameras; the screen printing method includes: S801. Sequentially place a plurality of battery cells into the loading position, determine the marking point coordinates of each battery cell based on the positioning method of the battery cell marking points, and determine the center coordinate and deflection angle of the battery cell based on the marking point coordinates; S802. Obtain the reference center coordinate and reference deflection angle of the printing screen zero position, determine the center coordinate difference based on the reference center coordinate and the center coordinate, and determine the deflection angle difference based on the deflection angle and the reference deflection angle; S803. Rotate the printing platform, transfer the battery cell to the printing position, and send the center coordinate difference and the deflection angle difference to the UVW platform. The UVW platform adjusts the printing platform based on the center coordinate difference and the deflection angle difference. After the adjustment is completed, print the slurry onto the battery cell; wherein, the positioning method of the battery cell marking points is the positioning method of the battery cell marking points according to any one of claims 1-6.

8. The screen printing method according to claim 7, characterized in that, The printing platform further includes a blanking position, and the blanking position includes an AOI optical inspection camera. The screen printing method further includes: S901. Determining the target center coordinates and target deflection angles of a plurality of the battery wafers based on the AOI optical inspection camera; S902. Determining a target center coordinate difference based on the center coordinates and the target center coordinates, and determining a target deflection angle difference based on the deflection angle and the target deflection angle; S903. Determining the target deflection angle difference and the target center coordinate difference corresponding to the deflection angle difference; S904. Obtaining the rotation limit of the UVW platform, and determining a plurality of deflection angle adjustment intervals based on the rotation limit; S905. Dividing the deflection angle difference based on the deflection angle adjustment intervals, and determining a compensation average value of the target deflection angle difference and the target center coordinate difference within the deflection angle adjustment intervals; S906. Compensating the next printing of the screen printing device based on the compensation average value.

9. The screen printing method according to claim 8, wherein, S906 includes: S1001. Obtaining a next battery wafer for the next printing, placing the next battery wafer in the loading position, and determining the battery wafer center coordinates and the battery wafer deflection angle of the next battery wafer; S1002. Obtaining the reference center coordinates and the reference deflection angle of the printing screen zero position, determining a battery wafer center coordinate difference based on the reference center coordinates and the battery wafer center coordinates, and determining a battery wafer deflection angle difference based on the battery wafer deflection angle and the reference deflection angle; S1003. Determining a target compensation average value for the next printing based on the battery wafer deflection angle difference and the deflection angle adjustment intervals; S1004. Rotating the printing platform, rotating the next battery wafer to the printing position, and sending the battery wafer center coordinate difference, the battery wafer deflection angle difference, and the target compensation average value to the UVW platform. The UVW platform adjusts the printing platform based on the battery wafer center coordinate difference, the battery wafer deflection angle difference, and the target compensation average value. After the adjustment is completed, printing the paste onto the next battery wafer to obtain the next battery wafer with the printed paste.

10. A positioning system for battery wafer marking points, wherein, for determining the marking point coordinates of a plurality of marking points in a battery wafer based on a contour camera and a plurality of overprint cameras; the positioning system for battery wafer marking points includes: A coordinate calibration module for calibrating the contour camera and the plurality of overprint cameras and unifying them to a calibration coordinate system; A contour feature parameter determination module for determining the contour feature parameters of the battery wafer in the contour camera coordinate system based on the contour camera; A marking point coordinate determination module, configured to determine a first conversion relationship between the contour camera coordinate system and the calibration coordinate system and a second conversion relationship between the overprint camera coordinate system and the calibration coordinate system, obtain distribution parameters of a plurality of marking points, and determine the marking point coordinates of the plurality of marking points based on the first conversion relationship, the second conversion relationship, the distribution parameters of the plurality of marking points, and the contour feature parameters.

11. A screen printing system Characterized in that It is applied to a screen printing device, and the screen printing device includes a movable printing platform and a UVW platform for adjusting the printing platform. The printing platform includes a loading position and a printing position, and the loading position includes a contour camera and a plurality of overprint cameras; The screen printing system includes: A marking point positioning module, configured to sequentially place a plurality of battery wafers into the loading position, determine the marking point coordinates of each battery wafer based on the positioning method of the battery wafer marking points, and determine the center coordinates and deflection angles of the battery wafers based on the marking point coordinates; A difference determination module, configured to obtain the reference center coordinates and reference deflection angles of the zero position of the printing stencil, determine the center coordinate difference based on the reference center coordinates and the center coordinates, and determine the deflection angle difference based on the deflection angle and the reference deflection angle; A printing module, configured to rotate the printing platform, transfer the battery wafer to the printing position, and send the center coordinate difference and the deflection angle difference to the UVW platform. The UVW platform adjusts the printing platform based on the center coordinate difference and the deflection angle difference. After the adjustment is completed, print the paste onto the battery wafer; Wherein, the positioning method of the battery wafer marking points is the positioning method of the battery wafer marking points according to any one of claims 1-6.

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