Screen damage detection method, screen damage detection system and screen printing equipment

Abstract

The present invention relates to the field of photovoltaic screen printing technology, and provides a screen damage detection method, a screen damage detection system, and a screen printing device. The screen damage detection method includes: acquiring an image, that is, acquiring an image of the screen to obtain a screen image; processing the image, that is, processing the information of the screen image to obtain the grayscale value of the screen image; judging the damage condition, that is, judging the damage condition of the screen according to the grayscale value of the screen image; wherein the damage condition of the screen includes ruptures and cracks. The present invention can detect damage to the screen in time, making it convenient for staff to replace it in time, and effectively avoiding the problem of multiple countertops needing to be cleaned due to failure to detect it in time, so it can effectively save the time spent on cleaning the countertops, and at the same time can also improve the equipment operation efficiency and the product qualification rate.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic screen printing, and in particular to a screen damage detection method, a screen damage detection system and a screen printing device. Background Art

[0002] At present, photovoltaic manufacturers mostly use screen printing to prepare electrodes and electric fields for solar cells. Among them, it involves the process of replacing the screen, which is indispensable in the screen printing process and can only be optimized to reduce the time spent on replacing the screen. The old replacement method is that the cell is rotated to the printing station through the mechanism. When the cell stops at the printing station, the scraper scrapes the slurry onto the cell through the pattern on the screen. During the scraping process, the screen will be damaged (the screen service life has expired, the cell has hidden cracks, there are foreign objects in the slurry, and there are stuck points on the surface of the cell, etc., which will cause the screen to be scraped). When the screen is damaged, the slurry will be scraped onto the table by the scraper. When the next station rotates over, the slurry will be scraped onto the table again. In this way, when it is detected by humans or publishing cameras, there will be slurry scraped on multiple tables, and then the screen will be removed, multiple tables will be cleaned, the belt will be cleaned, the table paper of multiple tables will be replaced, and a new screen will be installed. This is a complete set of screen replacement processes. In the prior art, if the machine cannot be shut down in time after the screen is damaged, the slurry will fall onto multiple surfaces, or the common situation of screen damage cannot be fully detected, resulting in inadequate detection and failure to discover screen damage in time. As a result, the cleaning time is too long, affecting the operating efficiency of the equipment and reducing the qualified rate of the workpiece (silicon wafer) to be processed.

[0003] In addition, the commonly used assembly line workpiece detection method in the prior art is not suitable for the detection of screen damage in screen printing equipment, mainly because it is limited by the characteristics of printing. Screen printing is a type of hole printing. The screen is an intermediate carrier. The slurry carried on the surface of the screen is printed on the battery cell below the screen through the printing holes on the screen. The detection of the printed screen needs to rely on the detection of the battery cell and the slurry, not just the detection of the screen itself. In the prior art, the detection of assembly line workpieces is based on the detection of the workpiece itself. The appearance of the processed workpieces is inspected one by one to detect whether there are surface defects. Therefore, it is not suitable for screen detection in screen printing equipment.

[0004] The above problems urgently require a complete set of screen detection methods for screen printing equipment to avoid the situation where screen damage is not discovered in time, resulting in slurry scraped on multiple surfaces and the cleaning takes a very long time. Summary of the invention

[0005] In order to solve the above-mentioned problem in the prior art that screen damage cannot be discovered in time and easily leads to slurry being scraped on multiple surfaces, resulting in a very long cleaning time, an object of the present invention is to provide a screen damage detection method.

[0006] Another object of the present invention is to provide a screen damage detection system.

[0007] Another object of the present invention is to provide a screen printing device.

[0008] To achieve the above-mentioned purpose, an embodiment of the first aspect of the present invention provides a screen damage detection method, comprising: acquiring an image, i.e., acquiring an image of the screen to obtain a screen image; processing the image, i.e., processing the information of the screen image to obtain a grayscale value of the screen image; judging the damage condition, i.e., judging the damage condition of the screen according to the grayscale value of the screen image; wherein the damage condition of the screen includes ruptures and cracks.

[0009] The screen damage detection method provided by the above embodiment of the present invention can obtain gray value information of the screen image by collecting the screen image and processing the collected screen image, and judge whether the screen is damaged according to the gray value information. In this way, it can be found in time when the screen is damaged, which is convenient for the staff to replace the screen in time, and effectively avoid the problem of multiple countertops needing to be cleaned due to failure to find it in time, so it can effectively save the time spent on cleaning the countertops, and at the same time improve the equipment operation efficiency and improve the product qualification rate.

[0010] In the above technical solution, the screen is a screen printed with slurry.

[0011] In any of the above technical solutions, collecting images includes: illuminating the screen area with a light source; and capturing an image of the screen area with a camera.

[0012] In this solution, the light source is used to assist the camera in shooting. Providing an appropriate light source can distinguish the screen area from the background area, thereby obtaining a high-quality image.

[0013] In any of the above technical solutions, processing the image includes: performing grayscale processing on the information of the halftone image through an image processing module to obtain the grayscale value of the grayscale image; and obtaining the number of pixels in the grayscale image that meet the grayscale value setting range through a pixel acquisition module.

[0014] In this solution, the number of pixels of an image refers to the number of pixels in the width and height directions of the bitmap image, that is, the number of pixels X in the length direction of the image and the number of pixels Y in the width direction of the image. The product of the two (X*Y) is called the number of pixels. It can be understood that an image with X*Y pixels includes X*Y pixels. By obtaining the number of pixels that meet the grayscale value setting range, it is possible to determine whether the screen is damaged based on the number of pixels, so that the image contrast can be converted into quantitative contrast, so the judgment method is more direct and the result is more accurate.

[0015] In any of the above technical solutions, judging whether the screen is broken includes: selecting a first detection area, that is, a complete detection area of ​​the screen, the number of pixels in the first detection area is m, and m is an integer greater than or equal to 1; obtaining a first number of pixels, that is, the number of pixels that satisfy a first grayscale value range; judging whether it is broken, that is, comparing the first number of pixels with a first preset number of image pixels; when the first number of pixels is greater than or equal to the first preset number of image pixels, judging that the screen is broken; when the first number of pixels is less than the first preset number of image pixels, judging that the screen is not broken; the first grayscale value range is greater than or equal to 0 and less than or equal to 40; when the screen is broken, the first preset number of image pixels is the number of image pixels at the broken part of the screen.

[0016] Cracks refer to large-scale damage to the screen. From the processed image, the workpiece below can be seen from the damaged part. The grayscale value range of the workpiece is different from the grayscale value of the screen. The grayscale range of a normal screen (referring to a screen without damage) is in the range of 80-140. If the screen is cracked, the grayscale range of the crack is only 5-35. Therefore, when judging whether the screen is cracked, the grayscale value of the workpiece is used as the basis for judgment. The workpiece is a silicon wafer, and the normal grayscale value range of a silicon wafer is 5-35. In order to avoid omissions, the grayscale value can be appropriately adjusted. Therefore, the range of 0-40 is selected as the grayscale value range of the silicon wafer, that is, the first grayscale value range, which can ensure that all pixels at the crack can be counted to avoid omissions due to errors.

[0017] The first number of pixels is the image taken when the device is running. After image processing, the number of pixels that meet the above-mentioned silicon wafer grayscale value range in the selected detection area (complete detection area) is compared with the number of pixels of the first preset image. It is possible to draw a conclusion on whether a crack occurs based on the quantitative relationship of the comparison.

[0018] In any of the above technical solutions, judging cracks in the screen includes: selecting a first detection area, i.e., a complete detection area of ​​the screen, the number of pixels in the first detection area is m, and m is an integer greater than or equal to 1; or selecting a second detection area, i.e., a partial detection area of ​​the screen, the edge of the second detection area is located at the edge of the screen and is arranged along the travel direction of the printing device, the number of pixels in the second detection area is n, and n is an integer greater than or equal to 1; obtaining a second number of pixels, i.e., the number of pixels that satisfy a second grayscale value range; judging whether there is a crack, i.e., comparing the second number of pixels with the second preset number of pixels of the image; when the second number of pixels is greater than or equal to the second preset number of pixels of the image, judging that cracks occur in the screen; when the second number of pixels is less than the second preset number of pixels of the image, judging that there is no crack in the screen; the second grayscale value range is greater than or equal to 250 and less than or equal to 255; when cracks occur in the screen, the second preset number of pixels of the image is the number of image pixels at the crack of the screen.

[0019] Cracks refer to tiny cracks or tiny gaps on the screen. At this time, a certain amount of slurry will fall on the workpiece below at the cracks, resulting in slurry concentration. That is, in the captured image, slurry can be observed from the cracks. The grayscale value range of the slurry is different from the grayscale value of the screen. Therefore, when judging whether there are cracks on the screen, the slurry grayscale value is selected as the basis for judgment. The slurry is photographed in white, and the grayscale value of white is 255. In order to reduce the interference of other factors, the grayscale value range of the slurry is appropriately adjusted. Therefore, 250-255 is identified as the grayscale value range of the slurry, that is, the second grayscale value range, which can ensure that the pixels at the cracks are counted to avoid omission due to errors, thereby improving the detection accuracy.

[0020] The second preset number of pixels is the number of pixels that meet the grayscale value range of the slurry after cracks appear on the screen, which is an empirical value. The second number of pixels is the number of pixels that meet the grayscale value range of the slurry in the selected detection area (complete detection area or partial detection area) after image processing in the image taken when the device is running. After comparing it with the second preset number of pixels, it can be concluded whether cracks appear based on the quantitative relationship of the comparison.

[0021] If the screen is damaged, it needs to be replaced in time. Generally, the main reasons for screen damage include the end of the screen service life, hidden cracks in the battery cell, foreign matter in the slurry, stuck points on the surface of the battery cell (for example, in the process before the battery cell printing process, burnt bumps appear on the edge of the battery cell during coating, etc.) or foreign matter retained on the surface of the battery cell, which can be summarized into two situations:

[0022] One is that the screen has reached the end of its service life, and the other is that the screen is affected by external foreign objects; either of the above two situations will affect the operation of the screen; accordingly, the detection method of screen breakage is mainly aimed at the damage caused when the screen has reached the end of its service life, and the detection method of screen cracks is mainly for the damage caused when the screen is scratched by the foreign objects mentioned above.

[0023] In the above scheme, the screen is broken, generally in the middle of the screen. In order to improve the accuracy of detection, detection is carried out in the complete detection area, that is, the first detection area.

[0024] Cracks appear on the screen, generally along the direction of the scraper, at the edge of the screen. To improve accuracy, it is preferred to detect in a local detection area. The local detection area is the second detection area. The local detection area has a small range, and the response of the corresponding parts of the equipment will be more sensitive and the operation speed will be faster. The response time of the corresponding parts can be reduced, and the detection accuracy is improved. In addition, you can also choose to detect in the complete detection area.

[0025] After each printing is completed, the screen is tested for damage, i.e., screen breakage detection and screen crack detection. Specifically, in the first case, the breakage detection can be performed first, and then the crack detection can be performed. It can be understood that: when it is determined that the screen is broken, the screen has been broken, and no crack detection is performed. When it is determined that the screen is not broken, the crack detection is performed. If it is determined that the screen is cracked, the screen is broken. If it is determined that the screen is not cracked, the screen is not broken; or, in the second case, the crack detection is performed first, and then the breakage detection is performed. It can be understood that: when it is determined that the screen is cracked, the screen has been broken, and no breakage detection is performed. When it is determined that the screen is not cracked, the breakage detection is performed. If it is determined that the screen is broken, the screen is broken. If it is determined that the screen is not broken, the screen is not broken.

[0026] Preferably, the second case is adopted because crack detection is performed in a local detection area. Compared with detection in the complete detection area, the response of the corresponding components is more sensitive, the operation speed is faster, and the response time is reduced.

[0027] An embodiment of the second aspect of the present invention provides a screen damage detection system for screen printing equipment, comprising: an image acquisition device for acquiring image information of the screen area; an image processing module for receiving the image information acquired by the image acquisition device and processing the image information to obtain a processed image; a control unit for determining the damage condition of the screen according to the processed image; the damage condition of the screen includes ruptures and cracks.

[0028] The screen damage detection system provided by the above embodiment of the present invention collects image information of the screen area through the set image acquisition module, then processes the collected image information through the image processing module, and then uses the control unit to determine whether the screen is damaged according to the processed image. In this way, it can be discovered in time when the screen is damaged, which is convenient for the staff to replace the screen in time, and effectively avoids the problem of multiple countertops needing to be cleaned due to failure to discover in time, so it can effectively save the time spent on cleaning the countertops, and at the same time can also improve the equipment operation efficiency and product qualification rate.

[0029] An embodiment of the third aspect of the present invention provides a screen printing device, comprising: a screen having slurry pre-stored on its surface; a transport device for transporting the workpiece to the bottom of the screen; a printing device for printing the slurry on the screen on the workpiece; and a screen damage detection system as in any technical solution in the second aspect above, for detecting damage to the screen.

[0030] The screen printing equipment provided by the above embodiment of the present invention can detect whether the screen is broken in time during use through the screen damage detection system. Therefore, the time spent on replacing the screen can be reduced during the printing process, thereby improving the production capacity of the entire screen printing line and greatly improving the operating efficiency of the equipment and the qualified rate of the product.

[0031] In any of the above technical solutions, the image acquisition device includes: a camera for capturing images of the screen area; a light source for providing lighting to the screen area; and a bracket for adjusting and fixing the camera and the light source; the light source is a bright light source, and the illumination area of ​​the light source covers the shooting area of ​​the camera.

[0032] In this solution, the light source should be compatible, and a bright light source should be selected to facilitate color contrast with the screen and slurry during shooting, which is beneficial to imaging contrast. Preferably, a white light source can be used.

[0033] In any of the above technical solutions, the screen printing equipment also includes: a visual positioning device, which is arranged at the front end of the transportation device and is used to photograph the front end processed parts on the transportation device; the camera and the light source are installed on the visual positioning device through a bracket.

[0034] In this solution, the visual positioning device can pick up the position of the workpiece by photographing the front-end workpiece on the transport device, and can send the position information of the workpiece to the control system so that the screen printing equipment can be accurately controlled. The front-end workpiece refers to the workpiece that has not yet run to the bottom of the screen and is about to run.

[0035] Additional aspects and advantages of the present invention will become apparent from the following description or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0037] Figure 1 is a module diagram of a screen damage detection system according to an embodiment of the present invention;

[0038] Figure 2 is a module diagram of a control unit in a screen damage detection system according to an embodiment of the present invention;

[0039] Figure 3 is a partial schematic diagram of a screen printing device according to an embodiment of the present invention;

[0040] Figure 4 yes Figure 3 A partial enlarged schematic diagram of the middle screen area;

[0041] Figure 5 is a schematic diagram of a support structure of an embodiment of the present invention;

[0042] Figure 6 yes Figure 5 A schematic diagram of the structure on the other side;

[0043] Figure 7 is an enlarged schematic diagram of a bracket installation location of a screen printing device according to an embodiment of the present invention;

[0044] Figure 8 is a top view of a screen printing device according to an embodiment of the present invention;

[0045] Fig. 9 is a schematic diagram of a first detection area according to an embodiment of the present invention;

[0046] Fig.10 is a schematic diagram of a second detection area according to an embodiment of the present invention;

[0047] Fig.11 It is one of the flow charts of the screen damage detection method according to one embodiment of the present invention;

[0048] Fig.12 This is a second flow chart of a screen damage detection method according to an embodiment of the present invention;

[0049] Fig.13 This is the third flow chart of the screen damage detection method according to an embodiment of the present invention.

[0050] in, Figures 1 to 10 The corresponding relationship between the reference numerals and component names in the figure is:

[0051] 10 Image acquisition device, 20 Image processing module, 30 Control unit, 32 Pixel acquisition module, 34 Pixel comparison module, 36 Result judgment module, 100 Screen, 110 Detection area, 112 First detection area, 114 Second detection area, 200 Transport device, 300 Printing device, 310 Knife group device, 400 Camera, 500 Light source, 600 Bracket, 610 First bracket, 612 First threaded hole, 614 First waist-shaped hole, 620 Second bracket, 622 Second threaded hole, 630 Third bracket, 632 First adjustment hole, 634 Second adjustment hole, 640 Fourth bracket, 642 Fourth threaded hole, 644 Fourth waist-shaped hole, 700 Visual positioning device, 800 Positioning adjustment device. DETAILED DESCRIPTION

[0052] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0053] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0054] Refer to the following Figures 1 to 13 A screen damage detection method, a screen damage detection system and a screen printing device according to some embodiments of the present invention are described.

[0055] like Figure 1 As shown, an embodiment of the first aspect of the present invention provides a screen damage detection system for screen printing equipment, comprising: an image acquisition device 10, an image processing module 20 and a control unit 30. The image acquisition device 10 is used to acquire image information of the screen area to obtain image information. The image processing module 20 is used to receive the image information obtained by the image acquisition device 10, and process the obtained image information to obtain a processed image. Afterwards, the control unit 30 can judge whether the screen 100 is damaged according to the obtained processed image.

[0056] The screen damage detection system provided by the above embodiment of the present invention collects and processes the image of the screen area and then makes a judgment and analysis. It can judge whether the screen is damaged in an intelligent way, so as to remind the personnel to replace the screen in time, which is helpful to save the time of replacing the screen and cleaning the table, and helps to improve production efficiency and improve the qualified rate of the workpiece to be processed.

[0057] In some embodiments, the image processing module 20 processes the image information as grayscale processing, and a grayscale image can be obtained after grayscale processing. The obtained grayscale image can still reflect the distribution and characteristics of the overall and local chromaticity and brightness levels of the entire image. Then the control unit 30 determines the damage of the screen 100 based on the obtained grayscale image. Using the grayscale image for judgment can reduce the amount of calculation of subsequent images. The grayscale image is a special color image with the same three components (RGB) of the color, and the grayscale value ranges from (0-255).

[0058] In certain embodiments, such as Figure 2 and Figure 8 As shown, the control unit 30 includes a pixel acquisition module 32, a pixel comparison module 34 and a result judgment module 36. The pixel acquisition module 32 is used to obtain the number of pixels in the detection area 110 in the grayscale image, and the number of pixels in the detection area 110 whose grayscale values ​​meet the grayscale value setting range. The pixel comparison module 34 compares the number of pixels whose grayscale values ​​meet the grayscale value setting range with the number of pixels in the preset image, specifically, to compare the numerical values. Then, the result judgment module 36 determines whether there is damage in the detection area 110 according to the comparison result of the pixel comparison module 34, and then draws a conclusion on whether the screen 100 is damaged.

[0059] In some embodiments, the detection area 110 is the first detection area 112. Specifically, the first detection area 112 is the screen area included in the walking path of the printing device 300, that is, the entire range of the detection area 110, which can be understood as a complete detection area; the number of pixels in the first detection area 112 is set to m. Detecting the first detection area 112 can improve the accuracy of detection.

[0060] In some embodiments, the detection area 110 is the second detection area 114, and the second detection area 114 can be any part of the detection area 110. Since cracks mostly appear at the edge of the screen 100, the second detection area 114 is preferably the edge area of ​​the detection area 110 and is set along the walking path of the printing device 300. Detecting only the edge area can reduce the detection area and improve the detection accuracy and efficiency. The number of pixels in the second detection area 114 is set to n, and n is less than m. When the second detection area 114 is detected, since the second detection area 114 will not cover the entire detection area 110, when the second detection area 114 is detected, the response of the corresponding parts of the equipment will be more sensitive, the operation speed will be faster, and the detection accuracy will be improved.

[0061] In some embodiments, when judging the damage of the screen 100 according to the comparison result of the pixel comparison module 34, when the number of pixels satisfying the gray value setting range is greater than or equal to the preset number of image pixels, it is judged that the screen 100 is damaged. When the number of pixels satisfying the gray value setting range is less than the preset number of image pixels, it is judged that the screen 100 is not damaged. Specifically:

[0062] Judgment when the screen 100 is broken:

[0063] (1) Set statistical parameters and comparison parameters.

[0064] When the damage is a crack, the workpiece located below the screen 100 can be seen from the crack in the captured image. Therefore, the grayscale value range of the workpiece can be used as the grayscale value setting range when the screen 100 is cracked. The grayscale value setting range is set to be less than or equal to a1, that is, the first grayscale value range, where a1 is the grayscale value range of the workpiece.

[0065] The workpiece is a silicon wafer, and the grayscale value range of the silicon wafer is 5-35. In order to avoid missing pixels due to errors during detection, the grayscale value range of the silicon wafer is appropriately expanded, that is, the grayscale value range a1 of the workpiece can be set to 0≤a1≤40. This can effectively avoid misjudgment due to missing pixels.

[0066] Statistical parameters: according to the processed grayscale image, the number c1 of first pixels that meet the first grayscale value setting range is counted.

[0067] Contrast parameter: that is, the number of pixels of the first preset image, set to b1; the number of pixels of the first preset image is: when the number of pixels in the first detection area is m, it is obtained through a large number of experiments that if the screen is broken, the number of pixels at the broken part meets the first grayscale value setting range.

[0068] (2) Select the detection area based on the statistical parameters of the detection area.

[0069] When performing crack detection on the screen 100, it is necessary to detect the complete detection area of ​​the screen 100. Fig. 9 As shown, the first detection area 112 is the complete detection area of ​​the screen 100, and the number of pixels in the first detection area 112 is m, where m is an integer greater than or equal to 1. When performing detection, the grayscale image is the grayscale image of the entire range of the first detection area 112, and when statistical parameters are calculated, the number of pixels that meet the grayscale value setting range will be counted in the grayscale image of the entire range of the first detection area 112.

[0070] (3) Determination of statistical parameters and comparative parameters.

[0071] The first number of pixels c1 that meets the first grayscale value setting range is compared with the contrast parameter, and the contrast parameter at this time is set to b1; when c1≥b1, it is judged as unqualified, indicating that the screen 100 is broken, and when c1<b1, it is judged as qualified, and the screen 100 is not broken.

[0072] In a specific embodiment, Fig. 9 As shown, at this time, the number of all pixels m in the first detection area 112 is 560,000. The arrow direction is the printing direction of the knife assembly device, A is the initial end of the knife assembly device, and B is the completion end of the knife assembly device. The number of pixels m in the first detection area 112 is set to 560,000. After a large number of experiments, it is known that when the number of pixels in the first detection area is 560,000, if the screen 100 is broken, the number of pixels that meet the first gray value setting range at the broken part is about 5000. Therefore, the screening condition of the first preset image pixel number when detecting the break is set to be greater than or equal to 5000, and the screening condition of b1 is greater than or equal to 5000.

[0073] Judgment when screen 100 is cracked:

[0074] (1) Set statistical parameters and comparison parameters.

[0075] When the damage is a crack, the slurry at the crack can be seen in the captured image. The gray value of the slurry is greater than the gray value of the screen 100, so at this time, the gray value setting range is set to be greater than or equal to a2, where a2 is the gray value range of the slurry, that is, the second gray value range.

[0076] Since the slurry is photographed in white, and the gray value of white is 255, in order to reduce the interference of other factors, the gray value range of the slurry is appropriately expanded, that is, the gray value range a2 of the slurry can be set to 250≤a2≤255. Therefore, 250-255 is identified as the gray value range of the slurry. At this time, the gray value setting range is set to be greater than or equal to the gray value range a2 of the slurry, that is, the pixels at the cracks can be counted, effectively avoiding omissions and improving detection accuracy.

[0077] Statistical parameters: According to the processed grayscale image, the number of pixels c2 that meet the second grayscale value setting range is counted.

[0078] Contrast parameters: the number of pixels of the second preset image is set to b2; the number of pixels of the second preset image is: when the number of pixels in the first detection area is m, it is obtained through a large number of experiments that if cracks occur in the screen, the number of pixels at the cracks meets the second grayscale value setting range.

[0079] (2) Select the detection area based on the statistical parameters of the detection area.

[0080] When performing crack detection on the screen 100, the entire detection area of ​​the screen 100 may be detected, that is, Fig. 9 The entire range of the first detection area 112 is shown to be detected.

[0081] (3) Determination of statistical parameters and comparative parameters.

[0082] The number of pixels c2 that meet the second gray value setting range is compared with the contrast parameter, and the contrast parameter at this time is set to b2. When c2≥b2, it is judged as unqualified, indicating that cracks appear on the screen 100, and when c2<b2, it is judged as qualified, and no cracks appear on the screen 100.

[0083] In one embodiment, the number of pixels in the first detection area 112 is set to 560,000, and the screening condition of the number of preset image pixels is greater than or equal to 3000, that is, the screening condition of b2 is greater than or equal to 3000. After a large number of experiments, it is known that when the number of pixels in the first detection area is 560,000, if cracks occur in the screen 100, the number of pixels that meet the second grayscale value setting range at the crack is about 3000. Therefore, the screening condition of the second preset number of image pixels when detecting cracks is set to be greater than or equal to 3000, and the screening condition of b2 is greater than or equal to 3000.

[0084] In a specific embodiment, Fig.10 As shown, when crack detection is performed on the screen 100, a local area of ​​the screen 100 is detected, that is, the second detection area 114 is detected. Among them, the second detection area 114 is preferably the edge area of ​​the detection area 110, and is set along the walking path of the printing device 300. When counting parameters, the number of pixels that meet the grayscale value setting range will be counted in the grayscale image of the second detection area 114. At this time, based on the number of pixels in the first detection area of ​​560,000, two local detection areas are selected respectively, and they are selected along the walking path of the printing device 300 at the edge of the screen, that is, two second detection areas 114 are selected. After a large number of experiments, it is known that cracks often occur in the area with a pixel number of 80,000 along the edge of the screen. Therefore, based on the purpose of improving the running speed detection accuracy and reducing the component response time, only the local area of ​​the screen can be detected, and the number of pixels n in the second detection area 114 is 80,000, and the screening condition of the number of pixels in the second preset image is greater than or equal to 3000. Because the number of pixels of the screen crack is irrelevant to whether the first detection area or the second detection area is selected, but is related to the size of the screen crack, when performing local area detection, the screening condition of the second preset image pixel number is still greater than or equal to 3000.

[0085] like Fig.10As shown, the arrow direction is the printing direction of the knife assembly device, and B is the completion end of the knife assembly device. At this time, the comparison parameter is set to b3, that is, the preset number of image pixels at this time. The number of pixels that meet the gray value setting range is set to c3, and c3 and b3 are compared. When c3≥b3, it is judged as unqualified, indicating that cracks appear on the screen 100. When c3<b3, it is judged as qualified, and no cracks appear on the screen 100.

[0086] Specifically, the detection principle of the system is that due to the difference in color of the screen 100, the scraper, the slurry and the silicon wafer itself, after the image grayscale processing, they each present different grayscale values, and combined with statistical probability judgment, whether there is an area with concentrated grayscale values, so as to judge whether the screen 100 is broken or cracked. The screen 100 is broken, which means that the screen 100 is damaged in a large area, and the silicon wafer is exposed in the visual field. The image area captured includes the scraper, the screen 100, the slurry, and the silicon wafer; the screen 100 is cracked, which means that the screen 100 is only slightly damaged, and the image area captured includes: the scraper, the screen 100, and the slurry (the slurry falls on the silicon wafer through the mesh of the screen 100, and only the slurry is visible in the mesh area of ​​the screen 100). A certain amount of slurry will fall on the silicon wafer, and then the slurry concentration phenomenon will occur. In screen printing, the normal situation is to photograph the screen 100. When the screen 100 is damaged, the slurry or silicon wafer will be exposed at the damaged part of the screen 100. When cracks appear, the slurry is detected, and when large-area cracks are detected, the silicon wafer is detected. The above-mentioned grayscale range value and the number of pixels of the image screening conditions refer to the more appropriate values ​​based on the statistics of a large number of cracks or cracks. Specifically, combined with Figure 8 As shown, the detection area is set to a specified range, that is, the operating range of the scraper in the knife assembly device 310.

[0087] In a preferred embodiment, after each printing is completed, the screen 100 is subjected to damage detection, that is, the screen 100 is subjected to breakage detection and crack detection, which may be the following two situations:

[0088] First case:

[0089] The crack detection can be performed first, and then the crack detection can be performed. It can be understood that: when it is determined that the screen 100 is cracked, the screen 100 has been damaged, and the crack detection is no longer performed. When it is determined that the screen 100 is not cracked, the crack detection is performed. If it is determined that the screen 100 is cracked, the screen 100 is damaged. If it is determined that the screen 100 is not cracked, the screen 100 is not damaged.

[0090] Second case:

[0091] Crack detection is performed first, and then rupture detection is performed. It can be understood that: when it is determined that cracks appear on the screen 100, the screen 100 has been damaged, and rupture detection is no longer performed. When it is determined that no cracks appear on the screen 100, rupture detection is performed. If it is determined that the screen 100 is ruptured, the screen 100 is damaged. If it is determined that the screen 100 is not ruptured, the screen 100 is not damaged.

[0092] Preferably, the second case is adopted because crack detection is performed in a local detection area. Compared with detection in the complete detection area, the response of the corresponding components is more sensitive, the operation speed is faster, and the response time is reduced.

[0093] The embodiment of the second aspect of the present invention provides a screen printing device, such as Figure 3 and Figure 4 As shown, it includes a screen 100, a transport device 200, a printing device 300, and a screen damage detection system in any one of the embodiments of the first aspect. The surface of the screen 100 is pre-stored with slurry. The transport device 200 is used to transport the workpiece to the bottom of the screen 100. The printing device 300 is located above the screen 100 and acts on the screen 100 to print the slurry pre-stored on the screen 100 on the workpiece on the transport device 200, thereby completing the printing operation on the workpiece. The screen damage detection system can detect the damage of the screen 100 to determine whether the screen 100 needs to be replaced.

[0094] In certain embodiments, such as Figure 4 As shown, the image acquisition device 10 in the screen damage detection system includes a camera 400, a light source 500 and a bracket 600. Figure 4 In the figure, the arrow direction is the printing direction, and the camera 400 is used to capture images of the screen area to obtain image information of the screen area. The light source 500 is used to provide illumination to the screen area to improve the image quality captured by the camera 400. The camera 400 and the light source 500 are both mounted on the bracket 600, and are mounted on the screen printing device through the bracket 600, so that the camera 400 and the light source 500 can be adjusted in angle under the action of the bracket 600, so that the camera 400 and the light source 500 can capture images of the screen area more accurately and clearly.

[0095] Specifically, the light source 500 is a bright color light source, preferably a white light source. The white light source can form a color difference contrast with the screen and the slurry during shooting, which is beneficial to imaging contrast.

[0096] In certain embodiments, such as Figure 7As shown, the screen printing device further includes a visual positioning device 700. The visual positioning device 700 is disposed at the front end of the transport device 200 and is used to photograph the front end processed parts on the transport device 200. At the same time, the camera 400 and the light source 500 are also fixedly mounted on the visual positioning device 700 through the bracket 600. It should be noted that the front end processed parts refer to the processed parts that have not yet run to and are about to run under the screen 100.

[0097] In certain embodiments, such as Figure 3 As shown, the screen printing device also includes an alignment adjustment device 800. After the visual positioning device 700 picks up the position information of the front-end workpiece, it will send the position information to the alignment adjustment device 800 through the control system. The screen 100 is set on the alignment adjustment device 800. After receiving the position information, the alignment adjustment device 800 can control the screen model to align the mesh of the screen 100 and the printing position of the workpiece to improve the printing accuracy. The printing device 300 is set above the alignment adjustment device 800. After the alignment adjustment device 800 aligns the screen 100 and the workpiece located below the screen 100, the printing device 300 prints the workpiece located below the screen 100.

[0098] In certain embodiments, such as Figure 5 and Figure 6 As shown, the bracket 600 includes a first bracket 610, a second bracket 620, a third bracket 630 and a fourth bracket 640. Among them, the rear end of the second bracket 620 is adjustable and mounted on the first bracket 610, so that the angle can be adjusted on the first bracket 610, and the camera 400 is installed at the front end of the second bracket 620. The front end of the third bracket 630 is connected to the rear end of the first bracket 610, and then the third bracket 630 is fixedly mounted on the visual positioning device 700 through the lower end to achieve the fixation of the third bracket 630. The upper end of the fourth bracket 640 is fixedly mounted on the lower end of the second bracket 620, and the light source 500 is adjustable and mounted at the lower end of the fourth bracket 640. When the angle of the second bracket 620 is adjusted, the angle of the camera 400 will also be adjusted accordingly, and at the same time, the fourth bracket 640 and the light source 500 installed below will be driven to adjust synchronously, so that the camera 400 and the light source 500 can always maintain a relatively fixed position and angle, which is convenient for image shooting.

[0099] In certain embodiments, such as Figure 5 and Figure 6As shown, a first threaded hole 612 and a first waist-shaped hole 614 are provided on the first bracket 610, and two second threaded holes 622 are provided on the second bracket 620, wherein one of the second threaded holes 622 corresponds to the first threaded hole 612 and is connected via a connecting piece, where rotation is possible; the other second threaded hole 622 corresponds to the first waist-shaped hole 614 and is also connected via a connecting piece, where the second threaded hole 622 can slide around the first threaded hole 612 within the range of the first waist-shaped hole 614, thereby adjusting the angle of the second bracket 620.

[0100] The third bracket 630 is provided with a first adjustment hole 632 and a second adjustment hole 634, wherein the third bracket 630 is fixedly connected to the first bracket 610 through the first adjustment hole 632, and then the third bracket 630 is fixedly installed on the visual positioning device 700 through the second adjustment hole 634. It should be noted that the first adjustment hole 632 and the second adjustment hole 634 are bar-shaped holes, so that when they are fixedly connected to the first bracket 610 or fixedly installed on the visual positioning device 700, they can be adjusted to a certain extent.

[0101] A fourth threaded hole 642 and a fourth waist-shaped hole 644 are provided on the lower side of the fourth bracket 640, and two threaded holes are provided on the outer shell of the light source 500, one of which corresponds to the fourth threaded hole 642 and is connected by a connecting piece, and can be rotated here; the other corresponds to the fourth waist-shaped hole 644, and is also connected by a connecting piece, and the threaded hole can slide around the fourth threaded hole 642 within the range of the fourth waist-shaped hole 644, so as to adjust the illumination angle of the light source 500.

[0102] By connecting the four brackets to each other, the remaining brackets, the camera 400, and the light source 500 can be fixed on the visual positioning device through the third bracket 630. In addition, the shooting and irradiation angles of the camera 400 and the light source 500 can be adjusted to ensure the quality of the photographs.

[0103] By using the screen printing equipment in this embodiment for production, when the screen is damaged, 10-20 minutes of replacement time can be saved, thereby improving the production capacity of the entire screen printing equipment and greatly improving the market competitiveness of the equipment.

[0104] The embodiment of the third aspect of the present invention provides a screen damage detection method, comprising the following steps:

[0105] Capturing an image means capturing an image of the screen 100 to obtain a screen image.

[0106] Processing the image means processing the information of the halftone image to obtain the grayscale value of the halftone image.

[0107] The damage condition is determined, that is, the damage condition of the screen 100 is determined according to the gray value of the screen image. The damage condition of the screen 100 includes cracks and fissures.

[0108] It should be noted that the screen plate 100 is a screen plate after slurry printing.

[0109] In one embodiment, collecting images includes: illuminating the screen area with a light source 500 and capturing images of the screen area with a camera 400 .

[0110] In one embodiment, processing the image includes: performing grayscale processing on the information of the halftone image through the image processing module 20 to obtain the grayscale value of the grayscale image; and obtaining the number of pixels in the grayscale image that meet the grayscale value setting range through the pixel acquisition module 32.

[0111] In one embodiment, determining the damage condition includes the following two conditions:

[0112] (1) Determining whether the screen 100 is broken includes:

[0113] A first detection area 112 is selected, ie, the complete detection area of ​​the screen 100 . The number of pixels in the first detection area 112 is m, where m is an integer greater than or equal to 1.

[0114] The first number of pixels is obtained, that is, the number of pixels that satisfy the first grayscale value range.

[0115] It should be noted that the first grayscale value range is greater than or equal to 0 and less than or equal to 40, and the first grayscale value range here is the grayscale value range of the workpiece. The first number of pixels is the number of pixels of the workpiece that can be seen from the rupture in the grayscale image after the screen 100 is ruptured.

[0116] Determine whether it is broken, that is, compare the first number of pixels with the first preset number of pixels. When the first number of pixels is greater than or equal to the first preset number of pixels, it is determined that the screen 100 is broken; when the first number of pixels is less than the first preset number of pixels, it is determined that the screen 100 is not broken.

[0117] It should be noted that the first preset number of image pixels is an empirical value, which is the empirical value of the number of image pixels at the broken part of the screen when the screen is broken. It can also be understood that the first preset number of image pixels is: when the number of pixels in the first detection area is m, after a large number of experiments, if the screen is broken, the number of pixels at the broken part that meet the first gray value setting range.

[0118] (2) Determine the screen 100 cracks, including:

[0119] A first detection area 112 is selected, i.e., the complete detection area of ​​the screen 100, the number of pixels in the first detection area 112 is m, and m is an integer greater than or equal to 1; or a second detection area 114 is selected, i.e., the partial detection area of ​​the screen 100, the second detection area 114 is located at the edge of the screen 100 and is arranged along the moving direction of the printing device 300, the number of pixels in the second detection area 114 is n, and n is an integer greater than or equal to 1.

[0120] The second number of pixels is obtained, that is, the number of pixels that satisfy the second grayscale value range.

[0121] It should be noted that the second grayscale value range is greater than or equal to 250 and less than or equal to 255. Here, the second grayscale value range is the grayscale value range of the slurry. The second number of pixels is the number of slurry pixels that can be seen from the crack in the grayscale image when a crack appears on the screen 100.

[0122] Determine whether cracks are generated, that is, compare the second number of pixels with the second preset number of pixels. When the second number of pixels is greater than or equal to the second preset number of pixels, it is determined that cracks are generated in the screen 100; when the second number of pixels is less than the second preset number of pixels, it is determined that no cracks are generated in the screen 100.

[0123] It should be noted that

[0124] When the first detection area is selected:

[0125] The first preset number of image pixels is: when the number of pixels in the first detection area is m, it is obtained through a large number of experiments that if cracks occur in the screen, the number of pixels at the cracks meets the first grayscale value setting range.

[0126] When the second detection area is selected:

[0127] The second preset number of image pixels is an empirical value, which is the empirical value of the number of image pixels at the crack of the screen when the crack occurs. It can also be understood that the second preset number of image pixels is: when the number of pixels in the second detection area is n, n is less than m, and after a large number of experiments, if the crack occurs in the screen, the number of pixels at the crack that meets the second gray value setting range.

[0128] In a specific embodiment, a screen damage detection method is described in more detail.

[0129] like Fig.11 As shown, the following steps are included:

[0130] Step 1000, conveying the slurry onto the screen.

[0131] After the slurry is transferred to the screen 100 , for subsequent printing, the knife assembly 310 of the printing device 300 scrapes the slurry evenly on the screen 100 , so that the slurry passes through the mesh of the screen 100 and is printed on the printing area of ​​the workpiece.

[0132] Step 2000: The transport device transports the workpiece to below the screen.

[0133] The workpiece is transported to the bottom of the screen 100 by the transport device 200 to facilitate subsequent printing.

[0134] Step 3000: The printing device performs unidirectional printing on the screen and the workpiece.

[0135] When the printing device 300 prints on the screen 100 and the workpiece, the blade assembly 310 on the printing device 300 will scrape the slurry on the surface of the screen 100 evenly on the surface of the screen 100, so that the slurry can pass through the mesh of the screen 100 and be printed on the workpiece below. Specifically, before the printing device 300 prints, the screen 100 and the workpiece are first aligned by the alignment adjustment device 800 to align the mesh of the screen 100 with the workpiece.

[0136] Step 4000: The image acquisition device acquires an image of the screen area and obtains image information.

[0137] Here, when the image of the screen area is captured, the screen 100 is a screen after slurry printing.

[0138] Step 5000: The image processing module processes the image information to obtain a processed image.

[0139] Here, when the image processing module 20 processes the image, it can specifically process the image in grayscale, so as to convert the image information into a grayscale image to obtain the grayscale value of the grayscale image. When the image processing module 20 processes the image, it will be started when the control system of the screen printing device monitors that there is image data to perform image processing.

[0140] Step 6000: The control unit determines the damage of the screen according to the processed image.

[0141] Here, when making a judgment, the control unit 30 may make a judgment based on the converted grayscale image. Making a judgment based on the grayscale image can reduce the amount of calculation during the judgment.

[0142] It should be noted that before carrying out all the steps, you first need to set the parameters through the software setting interface of the screen printing equipment. After the parameters are set, set them to automatic state, and then start running to start normal production of the screen printing equipment.

[0143] In certain embodiments, such as Fig.12 As shown, the image acquisition device 10 is used to acquire an image of the screen area and obtain image information, including the following steps:

[0144] Step 4100, illuminating the screen area with a light source.

[0145] After the light source 500 illuminates the screen area, the brightness of the screen area can be increased, and the image information collected during image acquisition can be clearer and more accurate.

[0146] Step 4200, taking an image of the screen area by using a camera.

[0147] Here, when the camera 400 is shooting, after the light source 500 is illuminated, a clearer image can be obtained, so that subsequent judgment is more accurate.

[0148] It should be noted that when the workpiece runs to the printing position below the screen 100, the knife assembly device 310 of the printing device 300 will start to run, and at the same time, the control system of the screen printing device will trigger the light source 500 to light up, and when the knife assembly device 310 runs to the distance completion position, it will trigger the camera 400 to take an image. Specifically, the time required for the camera 400 to start taking pictures and complete taking pictures is 15ms.

[0149] In certain embodiments, such as Fig.13 As shown, the control unit 30 determines the damage of the screen 100 according to the grayscale image, including the following steps:

[0150] Step 6100, obtaining the number c of pixels in the detection area that meet the grayscale value setting range through the pixel acquisition module.

[0151] Set the number of pixels that satisfy the grayscale value setting range to c.

[0152] Step 6200, compare c and b through a pixel comparison module.

[0153] The contrast parameter b, i.e., the preset number of image pixels, can be understood as the number of pixels in the grayscale image that meet the grayscale value range within the damage range, i.e., the number of pixels that meet the grayscale value range of the silicon wafer at the crack, or the number of pixels that meet the grayscale value range of the slurry at the crack.

[0154] The pixel comparison module 34 compares the number c of pixels satisfying the gray value setting range with the comparison parameter b.

[0155] Step 6300: judge the comparison result through the result judgment module.

[0156] Here, when the result judgment module 36 makes a judgment, according to the comparison result of the pixel comparison module 34, when c is greater than or equal to b, it means that damage has occurred, and the comparison result is unqualified. At this time, the display screen will display unqualified, and the alarm device will respond at the same time to remind the on-site personnel to handle and replace the screen in time. When c is less than b, it means that there is no damage, and the comparison result is qualified. At this time, the display screen will display qualified, and the printing device 300 will proceed to the next printing action.

[0157] It should be noted that after the result judgment module 36 judges the result, it will send a signal to the control system of the screen printing device at the same time, and the control system will control the screen of the screen printing device to display qualified or unqualified, and control the screen printing device to stop running, and respond to the alarm at the same time. After the staff finds the alarm, they remove the screen, clean one table, replace the table paper of another table, and install a new screen.

[0158] By detecting the screen of the screen printing equipment through the method, damage of the screen can be found in time, thereby saving 10-20 minutes of time for each replacement of the screen.

[0159] In the present invention, the terms "first", "second", and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance; the term "plurality" refers to two or more, unless otherwise clearly defined. The terms "installed", "connected", "connected", "fixed", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; "connected" can be a direct connection or an indirect connection through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0160] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by terms such as “upper”, “lower”, “left”, “right”, “front” and “back” are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or unit referred to must have a specific direction, be constructed and operated in a specific orientation, and therefore, cannot be understood as a limitation on the present invention.

[0161] In the description of this specification, the description of the terms "one embodiment", "some embodiments", "specific embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0162] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A screen damage detection method, characterized in that: include: Capturing images, i.e., capturing images of the screen to obtain a screen image; Processing the image, that is, processing the information of the halftone image to obtain the grayscale value of the halftone image; Determining the damage condition, that is, determining the damage condition of the screen according to the gray value of the screen image; Wherein, the damage of the screen includes rupture and cracks; The screen is a screen printed with slurry; The image acquisition includes: illuminating the screen area with a light source; and Taking an image of the screen area by a camera; The processing image comprises: Performing grayscale processing on the information of the halftone image through an image processing module to obtain a grayscale value of the grayscale image; The number of pixels in the grayscale image that meet the grayscale value setting range is obtained by a pixel acquisition module; Determining that the screen is broken includes: Selecting a first detection area, that is, a complete detection area of ​​the screen, wherein the number of pixels in the first detection area is m, where m is an integer greater than or equal to 1; Obtaining a first number of pixels, that is, the number of pixels satisfying a first grayscale value range; Determine whether it is broken, that is: comparing the first number of pixels with the number of pixels of a first preset image; When the first number of pixels is greater than or equal to the first preset number of pixels, determining that the screen is broken; When the first number of pixels is less than the first preset number of pixels, it is determined that the screen is not broken; The first grayscale value range is greater than or equal to 0 and less than or equal to 40; When the screen is broken, the first preset number of image pixels is the number of image pixels at the location where the screen is broken; Determining the screen crack includes: Selecting a first detection area, that is, a complete detection area of ​​the screen, wherein the number of pixels in the first detection area is m, where m is an integer greater than or equal to 1; or Selecting a second detection area, that is, a local detection area of ​​the screen, the second detection area is located at the edge of the screen and is set along the travel direction of the printing device, the number of pixels in the second detection area is n, and n is an integer greater than or equal to 1; Obtaining a second number of pixels, that is, the number of pixels satisfying a second grayscale value range; Determine whether there is a crack, that is: comparing the second number of pixels with the number of pixels of a second preset image; When the second number of pixels is greater than or equal to the second preset number of pixels of the image, determining that the screen has cracks; When the second number of pixels is less than the second preset number of pixels, it is determined that the screen has no cracks; The second grayscale value range is greater than or equal to 250 and less than or equal to 255; When a crack occurs on the screen, the second preset number of image pixels is the number of image pixels at the crack of the screen.

2. A screen damage detection system, characterized in that: For screen printing equipment, including: An image acquisition device, used to acquire image information of the halftone area to obtain a halftone image; An image processing module, used for receiving the information of the halftone image acquired by the image acquisition device, and performing grayscale processing on the information of the halftone image to obtain a grayscale value of the grayscale image; A control unit, used for judging the damage of the screen according to the gray value of the screen image; The damage of the screen includes cracks and fissures; The screen is a screen printed with slurry; Image acquisition includes: illuminating the screen area with a light source; and Taking an image of the screen area by a camera; Image processing includes: The number of pixels in the grayscale image that meet the grayscale value setting range is obtained by a pixel acquisition module; Determining that the screen is broken includes: Selecting a first detection area, that is, a complete detection area of ​​the screen, wherein the number of pixels in the first detection area is m, where m is an integer greater than or equal to 1; Obtaining a first number of pixels, that is, the number of pixels satisfying a first grayscale value range; Determine whether it is broken, that is: comparing the first number of pixels with the number of pixels of a first preset image; When the first number of pixels is greater than or equal to the first preset number of pixels, determining that the screen is broken; When the first number of pixels is less than the first preset number of pixels, it is determined that the screen is not broken; The first grayscale value range is greater than or equal to 0 and less than or equal to 40; When the screen is broken, the first preset number of image pixels is the number of image pixels at the location where the screen is broken; Determining the screen crack includes: Selecting a first detection area, that is, a complete detection area of ​​the screen, wherein the number of pixels in the first detection area is m, where m is an integer greater than or equal to 1; or Selecting a second detection area, that is, a local detection area of ​​the screen, the second detection area is located at the edge of the screen and is set along the travel direction of the printing device, the number of pixels in the second detection area is n, and n is an integer greater than or equal to 1; Obtaining a second number of pixels, that is, the number of pixels satisfying a second grayscale value range; Determine whether there is a crack, that is: comparing the second number of pixels with the number of pixels of a second preset image; When the second number of pixels is greater than or equal to the second preset number of pixels of the image, determining that the screen has cracks; When the second number of pixels is less than the second preset number of pixels, it is determined that the screen has no cracks; The second grayscale value range is greater than or equal to 250 and less than or equal to 255; When a crack occurs on the screen, the second preset number of image pixels is the number of image pixels at the crack of the screen.

3. A screen printing device, characterized in that: include: Screen, with slurry pre-stored on the surface; A transport device, used for transporting the workpiece to below the screen; A printing device, used for printing the slurry on the screen on the workpiece; and The screen damage detection system as described in claim 2 is used to detect the damage of the screen.

4. The screen printing device according to claim 3, characterized in that: The image acquisition device comprises: A camera, used for capturing an image of the screen area; A light source for providing illumination to the screen area; and A bracket, used for adjusting and fixing the camera and the light source; the light source is a bright light source; The illumination area of ​​the light source covers the shooting area of ​​the camera.

5. The screen printing device according to claim 4, characterized in that: The screen printing device also includes: A visual positioning device, arranged at the front end of the transport device, for photographing the workpiece on the transport device; The camera and the light source are mounted on the visual positioning device via the bracket.

Images