Square resistance measurement auxiliary device and square resistance measurement method

Abstract

The application discloses a square resistance measurement auxiliary device and a square resistance measurement method, relates to the technical field of semiconductors, and the method comprises the following steps: acquiring sample cell piece images of sample cell pieces; for each sample cell piece image, acquiring the image gray scale of the sample cell piece image; acquiring the square resistance of each sample cell piece; generating a correlation model according to the square resistance of each sample cell piece and the image gray scale corresponding to each sample cell piece, wherein the correlation model comprises a corresponding relationship between the square resistance of the cell piece and the image gray scale, and the correlation model is used for determining the square resistance of a target cell piece according to the image gray scale of the target cell piece. The problems that the cost of square resistance measurement is high and the cell piece is damaged due to square resistance measurement in the prior art are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to a sheet resistance measurement auxiliary device and a sheet resistance measurement method, and belongs to the technical field of semiconductors. BACKGROUND

[0002] In a photovoltaic cell manufacturing process, a key process is diffusion, and the purpose of diffusion is to form a PN junction. The quality of diffusion directly affects the quality level of the cell, and the key indicator for measuring the diffusion effect is the sheet resistance of the cell.

[0003] The existing sheet resistance measurement method is the four-probe method. However, the probe needs to be pressed on the surface of the cell during the measurement process, which will cause damage to the cell to some extent. Moreover, the probe used in the four-probe method is a consumable item that needs to be replaced regularly. Therefore, in the existing solution, the cost of sheet resistance measurement is high and the detected cell is damaged. SUMMARY

[0004] The present application relates to a sheet resistance measurement auxiliary device and a sheet resistance measurement method, and belongs to the technical field of semiconductors.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0006] According to the first aspect, the present application provides a sheet resistance measurement auxiliary device, which comprises a support, a reflecting plate, a light shield, a light source, a filter and a black and white camera.

[0007] The reflecting plate is placed at the bottom of the support.

[0008] The light shield is placed on the upper side of the reflecting plate, and opposite sides of the light shield are provided with through holes. The filter is placed in the light shield through the through holes. The upper surface of the light shield is used to place the cell to be measured.

[0009] The light source is arranged between the reflecting plate and the light shield, and the light emitting surface of the light source faces the reflecting plate.

[0010] The black and white camera is installed on the support, and the viewfinder direction of the black and white camera faces the light shield, which is used to shoot the cell image of the cell placed on the light shield.

[0011] Optionally, the bottom of the support is provided with a lead screw and a driving assembly. The lead screw is provided with a mounting assembly for mounting the reflecting plate. The lead screw and the driving assembly are connected, and the driving assembly is used to drive the mounting assembly to move horizontally and further drive the reflecting plate to translate.

[0012] Optionally, the mounting assembly is provided with two support rollers spaced apart for adjusting the orientation of the reflector placed on the support rollers.

[0013] Secondly, a method for measuring sheet resistance is provided, characterized in that the method includes:

[0014] Obtain sample battery cell images;

[0015] For each sample battery cell image, obtain the image grayscale of the sample battery cell image;

[0016] Obtain the sheet resistance of each sample battery cell;

[0017] Based on the sheet resistance of each sample battery cell and its corresponding image grayscale, a correlation model is fitted and generated. The correlation model includes the correspondence between the sheet resistance of the battery cell and the image grayscale. The correlation model is used to determine the sheet resistance of the target battery cell based on the image grayscale of the target battery cell.

[0018] Optionally, obtaining the sample cell image of the sample cell includes:

[0019] The sample battery cell image is obtained by means of a sheet resistance measurement auxiliary device, the sheet resistance measurement auxiliary device being the device described in the first aspect, and the sample battery cell is placed on the light shield.

[0020] Optionally, obtaining the image grayscale of the sample battery cell image includes:

[0021] The sample battery cell image is divided into an i*j chessboard, where i and j are positive integers;

[0022] For each chessboard, extract the grayscale value of each pixel within the chessboard;

[0023] Update the grayscale value of the pixel based on the grayscale values ​​of its neighboring pixels;

[0024] The image grayscale of the chessboard is calculated based on the grayscale values ​​of each pixel within the chessboard, and then the image grayscale of the battery cell image is calculated.

[0025] Optionally, updating the grayscale value of a pixel based on the grayscale values ​​of its neighboring pixels includes:

[0026] If the grayscale value of the nth pixel is g n The grayscale value of the (n-1)th pixel is g. n-1 The grayscale value of the (n+1)th pixel is g. n+1 If n is an integer greater than 1, then:

[0027] In |gn-1 -g n |>0.5g n or |g n-1 -g n |>0.5g n-1 or |g n+1 -g n |>0.5g n or |g n+1 -g n |>0.5g n+1 when g n＝ (g n-1 +g n+1 ) / 2.

[0028] Optionally, the fitting and generating of the correlation model according to the sheet resistance of each sample cell sheet and the image gray scale corresponding thereto comprises:

[0029] obtaining a correction factor, the correction factor comprising a time factor and / or an environmental factor;

[0030] fitting and generating the correlation model according to the sheet resistance of each sample cell sheet, the image gray scale corresponding thereto and the correction factor.

[0031] In a third aspect, a sheet resistance measurement method is provided, the method comprising:

[0032] obtaining a target cell sheet image of a target cell sheet;

[0033] obtaining an image gray scale of the target cell sheet image;

[0034] determining the sheet resistance of the target cell sheet according to a correlation model and the image gray scale, the correlation model comprising a corresponding relationship between the sheet resistance of the cell sheet and the image gray scale, the correlation model being a model fitted by the method of the second aspect.

[0035] Optionally, the obtaining of the target cell sheet image of the target cell sheet comprises:

[0036] obtaining the target cell sheet image of the target cell sheet by a sheet resistance measurement auxiliary device, the sheet resistance measurement auxiliary device being the device of the first aspect, and the target cell sheet being placed on the light shield cover.

[0037] Optionally, the obtaining of the image gray scale of the target cell sheet image comprises:

[0038] dividing the target cell sheet image into i*j chessboards, i and j being positive integers;

[0039] obtaining the image gray scale of each chessboard, and determining the obtained image gray scale of each chessboard as the image gray scale of the target cell sheet image.

[0040] Optionally, the sheet resistance of the target battery piece is determined according to the correlation model and the image gray scale of the target battery piece.

[0041] For each chessboard, the sheet resistance of each chessboard is determined according to the correlation model and the image gray scale of the chessboard.

[0042] The sheet resistance of the target battery piece is determined according to the calculated sheet resistances of the chessboards.

[0043] The sample battery piece image of a sample battery piece is obtained; for each sample battery piece image, the image gray scale of the sample battery piece image is obtained; the sheet resistance of each sample battery piece is obtained; and the correlation model is generated by fitting according to the sheet resistances of the sample battery pieces and the image gray scales corresponding to the sample battery pieces, the correlation model including the corresponding relationship between the sheet resistances of the battery pieces and the image gray scales, and the correlation model being used to determine the sheet resistance of a target battery piece according to the image gray scale of the target battery piece. The problem that the cost of sheet resistance measurement is high and the battery piece is damaged due to sheet resistance measurement in the prior art is solved, the correlation model is obtained, and the corresponding sheet resistance can be calculated according to the image gray scale and the correlation model only by obtaining the image of the battery piece to be measured during actual measurement, the cost of sheet resistance measurement is reduced, and the battery piece is not pressed or operated in the application, so that damage to the battery piece is avoided.

[0044] The above description is only a summary of the technical scheme of the present application. In order to more clearly understand the technical means of the present application, and to implement the content of the description, the following will be described in detail with the preferred embodiments of the present application and in conjunction with the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 The device schematic diagram of the sheet resistance measurement auxiliary device provided by an embodiment of the present application is shown;

[0046] Figure 2 The schematic diagram of the support in the sheet resistance measurement auxiliary device provided by an embodiment of the present application is shown;

[0047] Figure 3 Another device schematic diagram of the sheet resistance measurement auxiliary device provided by an embodiment of the present application is shown;

[0048] Figure 4 The partial schematic diagram of the sheet resistance measurement auxiliary device provided by an embodiment of the present application is shown;

[0049] Figure 5 The optical path schematic diagram of the sheet resistance measurement auxiliary device provided by an embodiment of the present application is shown;

[0050] Figure 6Another device schematic diagram of the square resistance measurement auxiliary device provided by an embodiment of the present application is shown in the figure;

[0051] Figure 7 A method flow chart of the square resistance measurement method provided by an embodiment of the present application is shown in the figure.

[0052] Figure 8 A schematic diagram of the correlation between the gray scale and the square resistance in the correlation model obtained by fitting is shown in the figure.

[0053] Figure 9 A method flow chart of the square resistance measurement method provided by an embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0054] The technical solutions of the present application will be described clearly and completely below with reference to the drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts fall within the protection scope of the present application.

[0055] In the description of the present application, it should be noted that the orientations or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and thus cannot be understood as indicating or implying that the devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0056] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0057] In addition, the technical features involved in the different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0058] Please refer to Figure 1 which shows a device schematic diagram of the square resistance measurement auxiliary device provided by an embodiment of the present application, as Figure 1As shown, the auxiliary device includes: bracket 1, reflector 2, light shield 3, light source 4, filter 5, and black and white camera 6.

[0059] The reflector 2 is placed at the bottom of the bracket 1.

[0060] Please refer to Figure 2 In one possible embodiment, the bottom of the bracket 1 is provided with a mounting component 7, a lead screw 8, and a drive component 9; wherein, the mounting component 7 is disposed in the lead screw 8 and is used to mount the reflector 2; the lead screw 8 and the drive component 9 are connected, and the drive component 9 can drive the mounting component 7 to move when working, thereby causing the reflector 2 to translate. In actual implementation, the drive component 9 can be a motor, and there is no limitation thereto.

[0061] In one possible embodiment, the reflector 2 is specularly reflective and its shape can be hemispherical, with the center point of the hemispherical arc surface mounted on the bracket 1 via the mounting assembly 7. For example, please refer to... Figure 3 It shows in Figure 2 The diagram shows the device after the reflector 2 is installed in the auxiliary device. The hemispherical reflector can generate a uniform light field, improve the image quality, and obtain more accurate grayscale images.

[0062] like Figure 2 and Figure 3 As shown, in one possible embodiment, the mounting assembly 7 has two support rollers spaced apart for adjusting the orientation of the reflector 2 placed on the support rollers. When a hemispherical reflector is used, the hemispherical reflector can be placed on the support rollers, and its orientation can be easily and conveniently adjusted by pushing the hemispherical reflector. To facilitate adjustment and final fixation of the orientation of the reflector 2 on the support rollers, the support rollers can be selected as rubber rollers with a certain friction.

[0063] A light shield 3 is placed on top of the reflector 2. Two opposite sides of the light shield 3 have through holes, through which the filter 5 is placed. The upper surface of the light shield 3 is used to place the battery cell to be tested. In practice, the light shield 3 can be rectangular, circular, square, or any other possible shape; this application does not limit this.

[0064] The light shield 3 can be a diffuse reflection light shield 3. The diffuse reflection light shield ensures that the light illuminating the battery cell is isotropic, avoiding localized overexposure and improving image quality. In one possible embodiment, please refer to... Figure 4The left and right sides of the light shield 3 are provided with through holes, and the filter 5 is installed in the light shield 3 through the through holes. In actual implementation, different wavelengths of light can be selected according to the thickness of the battery piece, that is, different wavelengths of the filter 5 can be selected according to the actual application scenario in the present application, and the present application does not make any limitation on this. In addition, the present application places the filter 5 in the light shield 3 through the through hole, so that the filter 5 can be replaced, and the versatility is enhanced.

[0065] The light source 4 is arranged between the reflecting plate 2 and the light shield 3, and the light emitting surface of the light source 4 faces the reflecting plate 2.

[0066] The light source 4 can be a mixed wavelength light source, which can be an incandescent lamp or an LED (light-emitting diode) white light source 4 in actual implementation. In the present application, the spectral range of the light source 4 can be from 600 nm to 1400 nm. Moreover, the light source 4 can be located at the geometric center position of the reflecting plate 2.

[0067] In addition, in order to realize the reflection of light, the light emitting surface of the light source 4 faces the reflecting plate 2. In one possible embodiment, please refer to Figure 5 , which shows a possible light path of the light source 4 in the reflecting plate 2.

[0068] The black and white camera 6 is installed on the support 1, and the view direction of the black and white camera 6 faces the light shield 3, which is used to shoot the battery piece image of the battery piece placed on the light shield 3. Moreover, in order to improve the shooting effect, the black and white camera 6 can be directly facing the light shield 3. In actual implementation, the support 1 can be a height-adjustable support. For example, in combination with Figure 1 , the support 1 includes a base, a support rod and a mounting portion perpendicular to the support rod. The mounting portion and the base are located on the same side of the support rod, and the black and white camera 6 can be installed in the mounting portion. The support rod can be a telescopic rod, and the height of the support rod can be adjusted according to actual needs, so as to adjust the height of the black and white camera 6 from the light shield 3. By setting the support 1 to be height-adjustable, the image quality of the battery piece image obtained by shooting can be improved according to actual needs during actual use.

[0069] In order to more stably place the light shield, the above-mentioned auxiliary device can further include a support column for supporting the light shield 3, wherein the height of the support column is greater than the height of the reflecting plate 2, that is, the distance between the reflecting plate 2 and the light shield 3 is the target distance. The angle of the reflecting plate 2 can be adjusted according to actual needs, so as to improve the image quality of the battery piece image obtained by the black and white camera 6.

[0070] In practical implementation, to ensure the stability of the light shield 3, there can be at least three support columns. Each support column is used to support a different position of the light shield 3, optionally supporting three different positions on the periphery of the light shield 3, and the maximum included angle formed by the three different positions is greater than 180°. For example, please refer to... Figure 6 Taking a device with four support columns as an example, this illustrates a schematic diagram of another possible implementation of the auxiliary device.

[0071] It should be noted that the above is only an example of a sheet resistance measurement auxiliary device including the aforementioned components. In actual implementation, it will be combined with... Figure 1 The auxiliary device may also include other components, such as a camera controller, a light source controller, and a host computer. The camera controller controls whether the black-and-white camera takes a picture, the light source controller controls whether the light source emits light, and the host computer controls the camera controller and the light source controller; however, this application does not limit the scope of the application.

[0072] In summary, an auxiliary device for sheet resistance measurement is provided, comprising: a bracket, a reflector, a light shield, a light source, a filter, and a monochrome camera; the reflector is placed at the bottom of the bracket; the light shield is placed on the upper side of the reflector, and through holes are provided on two opposite sides of the light shield, through which the filter is placed; the upper surface of the light shield is used to place the battery cell to be measured; the light source is positioned between the reflector and the light shield, with the emitting surface of the light source facing the reflector; the monochrome camera is mounted on the bracket, and the viewing direction of the monochrome camera is facing the light shield, for capturing images of the battery cell placed on the light shield. After capturing images of the battery cells, the correspondence between image grayscale and sheet resistance can be obtained based on the images and sheet resistance of each battery cell. Therefore, during actual measurement, only the image of the target battery cell needs to be acquired using the aforementioned auxiliary device to determine the specific sheet resistance based on this correspondence. This solves the problems of high cost and potential damage to the battery cells caused by sheet resistance measurement in existing technologies. It achieves the goal of acquiring the image grayscale of the battery cell, fitting a correlation model between the image grayscale and sheet resistance, and calculating the corresponding sheet resistance based on the image grayscale and correlation model during actual measurement. This reduces the cost of sheet resistance measurement, and this application avoids pressing or other operations on the battery cells, thus preventing damage.

[0073] In this application, by setting the reflector to be able to translate and rotate, the area and position of the light illuminating the light shield can be adjusted according to actual needs, which facilitates the detection of the local sheet resistance of the solar cells.

[0074] Please refer to Figure 7 It illustrates a flowchart of a sheet resistance measurement method provided in one embodiment of this application, as follows: Figure 7As shown, the method comprises:

[0075] Step 701, acquiring a sample cell sheet image of a sample cell sheet;

[0076] The sample cell sheet image of the sample cell sheet is acquired by the square resistance measurement auxiliary device, which is the device of the above-mentioned embodiments, and the sample cell sheet is placed on the light shield cover.

[0077] In actual implementation, each sample cell sheet can be placed above the light shield cover in turn, and the black-and-white camera performs shooting to obtain the sample cell sheet image of each sample cell sheet. Since the black-and-white camera is used for shooting in the present application, the obtained sample cell sheet image is a black-and-white image. Moreover, the use of the black-and-white camera for shooting improves the accuracy of the image gray scale obtained in subsequent calculation, thereby improving the measurement accuracy of the square resistance of the cell sheet.

[0078] In addition, the present application can select cell sheets with different square resistances as sample cell sheets, and the square resistance of the sample cell sheet can be a cell sheet with a square resistance increasing by a preset step from a first square resistance to a second square resistance. In one possible embodiment, the sample cell sheet can be from 1 ohm to 500 ohms, with a step of 0.1 ohm to 0.5 ohm.

[0079] Step 702, for each sample cell sheet image, acquiring an image gray scale of the sample cell sheet image;

[0080] Optionally, the present step can comprise:

[0081] First, dividing the sample cell sheet image into an i*j chessboard, i and j being positive integers;

[0082] Wherein, i and j can be the same or different, and no limitation is made thereon. In one possible embodiment, i=j=10 is taken as an example, each sample cell sheet can be divided into a 10*10 chessboard R n n=1~100.

[0083] Second, for each chessboard, extracting the gray scale value of each pixel point in the chessboard;

[0084] The chessboard includes i*j pixel points, and for each chessboard, the gray scale value of each pixel point in the chessboard can be extracted g n .

[0085] Third, updating the gray scale value of each pixel point according to the gray scale value of the adjacent pixel points of each pixel point;

[0086] If the gray scale value of the nth pixel point is g n , the gray scale value of the (n-1)th pixel point is g n-1 , and the gray scale value of the (n+1)th pixel point is g n+1, n is an integer greater than 1, then:

[0087] In |g n-1 -g n |>0.5g n Or |g n-1 -g n |>0.5g n-1 Or |g n+1 -g n |>0.5g n Or |g n+1 -g n |>0.5g n+1 When g n =(g n-1 +g n+1 ) / 2.

[0088] In a possible embodiment, the acquired gray values of the partial pixel points of the chessboard are shown in Table 1. It can be known from Table 1 that the gray of the pixel in the second row and the second column is abnormal, that is, there may be a foreign matter at this position. At this time, if the average gray is directly calculated as 131.1, and if the above method is used for calculation, because (255-105) > 105*0.5, 255 will be modified to 115, and the average gray is 115.6, which is closer to the actual situation and excludes the gray fluctuation caused by the abnormal point. That is, the above gray calculation method excludes the gray fluctuation caused by the abnormal point, improves the accuracy of the calculated gray, and further improves the accuracy of the subsequent correlation model.

[0089] 100 120 125 105 255 125 100 120 130

[0090] Table 1

[0091] Optionally, if the above condition is not met, the gray value of the pixel point does not need to be updated, which will not be described here.

[0092] Fourth, the image gray of the chessboard is calculated according to the gray values of the pixel points in the chessboard, and then the image gray of the battery piece image is calculated.

[0093] After the gray values of the pixel points in the chessboard are calculated, the image gray of each chessboard can be calculated. The image gray

[0094] After the image gray of each chessboard is calculated, the mean value of the image gray of each chessboard can be calculated, and then the image gray of the sample battery piece is obtained.

[0095] Step 703, acquiring the square resistance of each sample battery piece;

[0096] In a possible embodiment, the square resistance of each sample battery piece is measured by a four-probe measurement method.

[0097] At step 704, a correlation model is fitted according to the sheet resistance of each sample battery piece and the image gray scale corresponding to each sample battery piece, the correlation model including a corresponding relationship between the sheet resistance of the battery piece and the image gray scale, and the correlation model being used to determine the sheet resistance of the target battery piece according to the image gray scale of the target battery piece.

[0098] Optionally, the correlation model can be fitted by least squares method or Hough transform method or RANSAC (RANdom SAmple Consensus) according to each sheet resistance and the image gray scale corresponding to each sheet resistance.

[0099] In actual implementation, the present step can include:

[0100] First, an offset factor is obtained, the offset factor including a time factor and / or an environmental factor;

[0101] Since the environmental temperature and the time of absorbing photons can affect the determination of the final sheet resistance, in the present application, the offset factor can include at least one of the time factor and the environmental factor.

[0102] When the offset factor includes the time factor, the step of obtaining the time factor includes: selecting a fixed battery piece, measuring the resistance value R0 of the battery piece in advance at an environmental temperature T0 using a four-probe method, placing the battery piece under a light source while maintaining the temperature T0, taking a picture every 10 seconds, calculating the gray scale value G, and then plotting a plurality of points in a t-G coordinate system, thereby obtaining the function of ε1(t), and taking the function of ε1(t) as the time factor. Similarly, the environmental factor can be obtained by a similar calculation method, and it is assumed that the obtained environmental factor is ε2(T).

[0103] In one possible embodiment, it is assumed that the offset factor includes both the time factor and the environmental factor, and the offset factor b is:

[0104] Second, a correlation model is fitted according to the sheet resistance of each sample battery piece, the image gray scale corresponding to each sample battery piece, and the offset factor.

[0105] Similarly, the fitting can be performed by least squares method or Hough transform method or RANSAC, and no limitation is made in this regard.

[0106] In one possible embodiment, the fitted correlation model is f(G, R) + b, and b = ε1(t) + ε2(T).

[0107] Optionally, please refer to Figure 8 which shows a schematic diagram of a possible correlation relationship between the gray scale and the sheet resistance in the fitted correlation model.

[0108] In summary, by acquiring a sample cell sheet image of a sample cell sheet; for each sample cell sheet image, acquiring an image gray scale of the sample cell sheet image; acquiring a square resistance of each sample cell sheet; according to the square resistance of each sample cell sheet and the image gray scale corresponding thereto, fitting to generate a correlation model, the correlation model including a corresponding relationship between the square resistance and the image gray scale of the cell sheet, the correlation model being used to determine the square resistance of a target cell sheet according to an image gray scale of the target cell sheet. The problem that the square resistance measurement in the prior art is high in cost and causes damage to the cell sheet due to the square resistance measurement is solved, the correlation model can be fitted, and thus only the image of the cell sheet to be measured needs to be acquired to calculate the corresponding square resistance according to the image gray scale and the correlation model in actual measurement, the cost of the square resistance measurement is reduced, and the application does not press the cell sheet and avoids damage to the cell sheet.

[0109] Please refer to Figure 9 which shows a method flowchart of the square resistance measurement method provided by an embodiment of the application, as Figure 9 shown, the method includes:

[0110] Step 901, acquiring a target cell sheet image of a target cell sheet;

[0111] The target cell sheet image of the target cell sheet is acquired by a square resistance measurement auxiliary device, the square resistance measurement auxiliary device is the device as above, and the target cell sheet is placed on a light shield cover.

[0112] This step is similar to step 701 in the above embodiment, and will not be described here again.

[0113] Step 902, acquiring an image gray scale of the target cell sheet image;

[0114] Optionally, this step includes:

[0115] First, dividing the target cell sheet image into i*j chessboards, i and j being positive integers;

[0116] This step is similar to the division step in the above embodiment, and will not be described here again.

[0117] Second, acquiring an image gray scale of each chessboard, and determining the acquired image gray scale of each chessboard as the image gray scale of the target cell sheet image.

[0118] Optionally, this step includes:

[0119] (1) for each chessboard, extracting a gray scale value of each pixel point in the chessboard;

[0120] (2) updating the gray scale value of the pixel point according to the gray scale value of the adjacent pixel point of the pixel point;

[0121] If the gray value of the nth pixel point is g n , the gray value of the n-1th pixel point is g n-1 , the gray value of the n+1th pixel point is g n+1 , and n is an integer greater than 1, then:

[0122] When |g n-1 -g n |>0.5g n or |g n-1 -g n |>0.5g n-1 or |g n+1 -g n |>0.5g n or |g n+1 -g n |>0.5g n+1 , g n＝ (g n-1 +g n+1 ) / 2.

[0123] (3) Calculate the image gray value of the chessboard according to the gray values of the pixel points in the chessboard.

[0124] Step 903, determine the square resistance of the target battery sheet according to the association model and the image gray value, the association model includes the corresponding relationship between the square resistance of the battery sheet and the image gray value, and the association model is a model fitted by the above method.

[0125] Optionally, the step includes:

[0126] First, for each chessboard, determine the square resistance of each chessboard according to the association model and the image gray value of the chessboard.

[0127] Optionally, the image gray value of each chessboard is input into the association model, and the association model can output the corresponding square resistance.

[0128] For example, after the calculated image gray value G is input into the association model f(G, R) + b, the corresponding square resistance can be obtained.

[0129] Second, determine the square resistance of the target battery sheet according to the calculated square resistances of the chessboards.

[0130] After the square resistances of the chessboards are calculated, the average of the square resistances of the chessboards is taken as the square resistance of the target battery sheet, that is, the square resistance of the target battery sheet is

[0131] The application can obtain the sheet resistance distribution in the target battery piece by calculating the sheet resistance of each chessboard, that is, the total sheet resistance of the target battery piece can be output, and the sheet resistance distribution in the target battery piece can be obtained, which provides help for improvement of the battery piece processing technology.

[0132] It should be noted that the application is only illustrated by calculating the image gray scale of each chessboard, then calculating the sheet resistance of each chessboard, and calculating the sheet resistance of the battery piece according to the sheet resistance of each chessboard. In actual implementation, after the image gray scale of each chessboard is calculated, the image gray scale of the battery piece can also be calculated according to the image gray scale of each chessboard, and then the sheet resistance of the battery piece can be calculated according to the image gray scale of the battery piece and the correlation model. The application does not limit this.

[0133] In summary, by obtaining the target battery piece image of the target battery piece, obtaining the image gray scale of the target battery piece image, determining the sheet resistance of the target battery piece according to the correlation model and the image gray scale, the correlation model includes the corresponding relationship between the sheet resistance of the battery piece and the image gray scale, and the correlation model is a model fitted by the above method. The problem that the cost of sheet resistance measurement is high and the battery piece is damaged due to sheet resistance measurement in the prior art is solved. After the correlation model is obtained, only the image of the battery piece to be measured is needed to calculate the corresponding sheet resistance according to the image gray scale and the correlation model, the cost of sheet resistance measurement is reduced, and the application does not press the battery piece to avoid damage to the battery piece.

[0134] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described, but as long as the combinations of the technical features do not exist contradictory, they should be considered as the scope of the present application.

[0135] The above-described embodiments only express several embodiments of the application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be noted that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of the present application. Therefore, the scope of protection of the present application should be subject to the appended claims.

Claims

1. A square resistance measurement aid, characterized by, The auxiliary device includes: a bracket, a reflector, a light shield, a light source, a filter, and a black and white camera; The reflector is placed at the bottom of the bracket; the reflector is specular and hemispherical in shape. The light shield is placed on the upper side of the reflector. Two opposite sides of the light shield have through holes. The filter is placed in the light shield through the through holes. The upper surface of the light shield is used to place the battery cell to be tested. The light source is disposed between the reflector and the light shield, and the light-emitting surface of the light source faces the reflector; The black-and-white camera is mounted on the bracket, and the camera's viewfinder is directed towards the lens hood, for taking images of the battery cells placed on the lens hood.

2. The supplementary device of claim 1, wherein, The bottom of the bracket is provided with a lead screw and a drive assembly. The lead screw contains an installation assembly for mounting the reflector. The lead screw and the drive assembly are connected, and the drive assembly is used to drive the installation assembly to move horizontally, thereby causing the reflector to move horizontally.

3. The supplementary device of claim 2, wherein, The mounting assembly has two support rollers spaced apart for adjusting the orientation of the reflector placed on the support rollers.

4. A method of measuring the square resistance, characterized by, The method includes: Acquiring a sample image of a sample battery cell includes: acquiring the sample image of the sample battery cell through a sheet resistance measurement auxiliary device, wherein the sheet resistance measurement auxiliary device is the device as described in any one of claims 1 to 3, and the sample battery cell is placed on the light shield; For each sample battery cell image, obtain the image grayscale of the sample battery cell image; Obtain the sheet resistance of each sample battery cell; Based on the sheet resistance of each sample battery cell and its corresponding image grayscale, a correlation model is fitted and generated. The correlation model includes the correspondence between the sheet resistance of the battery cell and the image grayscale. The correlation model is used to determine the sheet resistance of the target battery cell based on the image grayscale of the target battery cell.

5. The method of claim 4, wherein, The step of obtaining the image grayscale of the sample battery cell image includes: The sample battery cell image is divided into an i*j chessboard, where i and j are positive integers; For each chessboard, extract the grayscale value of each pixel within the chessboard; Update the grayscale value of the pixel based on the grayscale values ​​of its neighboring pixels; The image grayscale of the chessboard is calculated based on the grayscale values ​​of each pixel within the chessboard, and then the image grayscale of the battery cell image is calculated.

6. The method of claim 5, wherein, The step of updating the grayscale value of a pixel based on the grayscale values ​​of its neighboring pixels includes: If the gray value of the nth pixel point is g n , the gray value of the n-1th pixel point is g n-1 , the gray value of the n+1th pixel point is g n+1 , and n is an integer greater than 1, then: In |g n-1 -g n |>0.5g n or |g n-1 -g n |>0.5g n-1 or |g n+1 -g n |>0.5g n or |g n+1 -g n |>0.5g n+1 then let g n＝ (g n-1 + g n+1 ) / 2.

7. The method according to any one of claims 4 to 6, characterized in that, The step of fitting and generating a correlation model based on the sheet resistance of each sample battery cell and its corresponding image grayscale includes: Obtain correction factors, which include time factors and / or environmental factors; The correlation model is generated by fitting the sheet resistance of each sample battery cell, its corresponding image grayscale, and the correction factor.

8. A method of measuring the square resistance, characterized by, The method includes: Acquiring an image of a target battery cell includes: acquiring the image of the target battery cell using a sheet resistance measurement auxiliary device, wherein the sheet resistance measurement auxiliary device is the device as described in any one of claims 1 to 3, and the target battery cell is placed on the light shield. acquiring image gray scale of the target cell sheet image; determining sheet resistance of the target cell sheet according to the correlation model and the image gray scale, the correlation model including corresponding relationship between sheet resistance and image gray scale of the cell sheet, the correlation model being a model fitted by the method in any one of claims 4 to 7.

9. The method of claim 8, wherein, The acquiring of the image gray scale of the target cell sheet image comprises: dividing the target cell sheet image into i*j chessboards, i and j being positive integers; acquiring image gray scale of each chessboard, and determining the acquired image gray scale of each chessboard as the image gray scale of the target cell sheet image.

10. The method of claim 9, wherein, The determining of the sheet resistance of the target cell sheet according to the correlation model and the image gray scale comprises: for each chessboard, determining sheet resistance of each chessboard according to the correlation model and the image gray scale of the chessboard; and determining the sheet resistance of the target cell sheet according to the calculated sheet resistance of each chessboard.

Images