Defect detection mechanism for screen printing and screen printing process

Abstract

The application discloses a kind of screen printing flaw detection mechanism and screen printing flow, it is related to printing flaw detection, and its technical solution main points are: including frame and the two guide rails of fixed connection on the top surface of frame, bearing platform is slidably connected on guide rail, heating component for heating ink is equipped on screen printing plate, temperature information acquisition module, image acquisition module, display module are equipped on frame.The position of ink is judged by the difference of temperature, even if the color difference between ink and textile is not obvious, it does not affect the collection of information, the thermal image is generated by the color identification of different temperatures, and the image information of the surface of textile is collected by camera, the thermal image and the image information collected by camera are image processed, the accuracy of judging ink distribution is improved by the combination of the two, to find the pattern change flaw caused by the position offset of ink on textile, and finally feedback to operator through display screen.

Description

Technical Field

[0001] This invention relates to the detection of printing defects, and more specifically, to a defect detection mechanism and a screen printing process for screen printing. Background Technology

[0002] Screen printing, as an important printing technology, is characterized by simple equipment, convenient operation, strong adaptability, and low cost. It is widely used in various fields, such as textile printing, paper printing, plastic printing, wood product printing, metal product printing, and glass and ceramic product printing. Its basic principle is to use the principle that ink can pass through the mesh openings of the screen printing plate in the image areas, while ink cannot pass through the mesh openings in the non-image areas. However, in the actual printing process, due to the influence of various factors, such as the viscosity of the ink, the pressure of the squeegee, and the tension of the screen, various defects often occur, such as uneven printing, missing prints, broken lines, and blurring.

[0003] For defect detection in screen printing, traditional methods mostly rely on manual visual inspection. This method is not only inefficient but also easily affected by human factors, making it difficult to guarantee the accuracy and consistency of the detection results. Therefore, with the continuous development of image processing and machine vision technologies, automated and intelligent defect detection agencies have been gradually introduced into the screen printing field. These defect detection agencies typically acquire images of printed materials, use image processing algorithms to preprocess the images such as grayscale conversion, filtering and noise reduction, brightness equalization, and contrast equalization, and then use techniques such as template matching, feature extraction, and deep learning to identify and classify defects.

[0004] However, defect detection agencies mainly rely on image information provided by cameras. In cases where the color difference is not obvious, such as when the color of textile ink is similar to the color of textile fabric, errors can easily occur during image processing, causing the defect detection agency to report incorrect results during inspection. This results in the operator receiving defect information that does not match the actual defect information. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a defect detection mechanism and screen printing process for screen printing.

[0006] The above-mentioned technical objective of the present invention is achieved through the following technical solution: a defect detection mechanism for screen printing, comprising a frame and two guide rails fixedly connected to the top surface of the frame, a support platform slidably connected to the guide rails, the upper part of the frame being divided into a detection area and a processing area along the length of the guide rails, a screen printing plate being provided in the processing area, a heating component for heating ink being provided on the screen printing plate, and a temperature information acquisition module, an image acquisition module, and a display module being provided on the frame;

[0007] The temperature information acquisition module includes a first temperature sensor, which is located at one end of the detection area near the processing area and is higher than the support platform.

[0008] The image acquisition module includes a camera, which is located in the detection area, above the support platform, and on the side of the first temperature sensor away from the detection area.

[0009] The display module includes an interactive component and a connecting cable. The first temperature sensor and the camera are both connected to the interactive component via the connecting cable.

[0010] The present invention is further configured such that: the temperature information acquisition module further includes a second temperature sensor, the second temperature sensor is fixedly connected to the bottom of the support platform, and the second temperature sensor is communicatively connected to the interactive component.

[0011] The present invention is further configured such that: a photosensitive sensor is fixedly connected to one side of the first temperature sensor, a plurality of LED beads are fixedly connected to the top edge of the support platform, the LED beads are linearly arrayed along the length direction of the guide rail, the photosensitive sensor is located directly above the movement path of the LED beads, and the photosensitive sensor is electrically connected to the interactive component.

[0012] The present invention is further configured such that: the screen printing plate is composed of a border and a plurality of metal wires, the heating component is in contact with the metal wires, the metal wires are made of aluminum-copper alloy, and the diameter of the metal wires is not less than 0.08 mm.

[0013] The present invention is further configured such that: the frame includes an upper frame and a lower frame, the upper frame is fixedly connected to the heating component, the lower frame is fixedly connected to the metal wire, and the upper frame and the lower frame are detachably connected.

[0014] A screen printing process using the aforementioned defect detection mechanism includes the following steps:

[0015] S1. Preheating: The ink on the screen printing plate is heated by a heating element.

[0016] S2. Placement: Place the textile on the support platform;

[0017] S3. Positioning: The location information of the textile after placement is obtained through the camera, and the textile is positioned.

[0018] S4. Printing: The carrier table enters the processing area from the inspection area along the guide rail, and the ink is pressed down by the scraper to form a pattern on the surface of the textile.

[0019] S5. Collect temperature information. During the process of the carrier moving from the processing area to the detection area, the temperature of the textile surface is detected by the first temperature sensor, and the temperature difference between each block is recorded.

[0020] S6. Acquire image information: When the carrier platform is completely located in the detection area, acquire image information of the textile surface through the camera;

[0021] S7. By comparing the location information of the higher temperature area obtained in S5, the location information of the ink is simulated, and the simulated information is combined with the image information collected in S6 to ensure the accuracy of the ink location information.

[0022] S8. Feedback: Based on the ink position information obtained in S7, compare it with the expected ink position to determine the number and location of defects, and then provide feedback to the operator through the interactive component.

[0023] The present invention is further configured such that, in step S3, the temperature of each part of the textile is detected by a second temperature sensor, thereby detecting whether there is a significant local temperature difference in the textile before printing.

[0024] The present invention is further configured such that: in step S5, a photosensitive sensor detects the LED beads passing below the photosensitive sensor, thereby obtaining the position of the first temperature sensor relative to the support platform.

[0025] The present invention is further configured such that, in step S3, the accuracy of the placement of the textile is determined by a camera based on the position of the LED beads, thereby reducing defective products caused by misalignment during textile printing.

[0026] In summary, the present invention has the following beneficial effects: the position of ink is determined by temperature difference, and the information acquisition is not affected even if the color difference between ink and textile is not obvious. The temperature difference is marked by color to generate thermal images, and then image information of the textile surface is collected by a camera. The thermal images and the image information collected by the camera are processed, and the combination of the two improves the accuracy of ink distribution judgment. In this way, the pattern change defects on the textile caused by ink position displacement can be found, and finally the feedback is given to the operator through the display screen. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of the present invention;

[0028] Figure 2 This is a partial cross-sectional view of the present invention;

[0029] Figure 3 for Figure 2 Enlarged view of point A in the middle;

[0030] Figure 4 for Figure 2 Enlarged view of point B in the middle;

[0031] Figure 5 for Figure 2 A magnified view of point C in the middle.

[0032] In the diagram: 1. Frame; 2. Guide rail; 3. Support platform; 4. Heating component; 5. First temperature sensor; 6. Camera; 7. Interactive component; 8. Connecting cable; 9. Second temperature sensor; 10. Photosensitive sensor; 11. Top frame; 12. Bottom frame; 13. LED. Detailed Implementation

[0033] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0034] Example 1: A defect detection mechanism for screen printing, such as... Figures 1-3 As shown, the system includes a frame 1 and two guide rails 2 fixedly connected to the top surface of the frame 1. A support platform 3 is slidably connected to the guide rails 2. The upper part of the frame 1 is divided into a detection area and a processing area along the length of the guide rails 2. A screen printing plate is provided in the processing area, and a heating element 4 for heating ink is provided on the screen printing plate. The frame 1 is equipped with a temperature information acquisition module, an image acquisition module, and a display module. The temperature information acquisition module includes a first temperature sensor 5, which is located at the end of the detection area closer to the processing area and is higher than the support platform 3. The image acquisition module includes a camera 6, which is located in the detection area and is higher than the support platform 3. The camera 6 is located on the side of the first temperature sensor 5 away from the detection area. The display module includes an interactive component 7 and a connecting cable 8. The first temperature sensor 5 and the camera 6 are both connected to the interactive component 7 through the connecting cable 8.

[0035] Specifically, two guide rails 2 are fixedly connected to the top surface of the frame 1. An operating table is located at one end of the frame 1. The end of the guide rail 2 within the detection area is close to the operating table, and the other end is located within the processing area. In the processing area, from the guide rail 2 upwards, are a screen printing plate, a squeegee, and a heating element 4 located on the upper surface of the screen printing plate. The heating element 4 is square-shaped, and the squeegee moves horizontally within the frame of the heating element 4. The area enclosed by the heating element 4 is larger than the area of ​​the top surface of the support platform 3. In the detection area, along the direction away from the processing area, are a first support, a second support, and an interactive component 7. The first support supports a first temperature sensor 5, which is an infrared temperature sensor. The first temperature sensor 5 is a linear array, and the first temperature sensor... The direction of the linear array 5 is perpendicular to the length direction of the guide rail 2, and the direction of the infrared temperature sensor array is perpendicular to the length direction of the guide rail 2. The first temperature sensor 5 is set close to the processing area, which reduces the distance the textile travels from the completion of printing to being detected by the first temperature sensor 5, reduces the time for heat exchange between the outside and the ink and the time for heat transfer between the ink and the textile, and ensures the accuracy of the first temperature sensor 5. The second bracket is used to support the camera 6. A horizontal plate is slidably connected to the top of the second bracket, and the camera 6 is clipped onto the horizontal plate. The interactive component 7 includes a housing, a microcomputer, and a display screen. The interactive component 7 is located on one side of the operating table. A wire clamp for constraining the connecting line 8 is integrally formed at the end of the horizontal plate near the interactive component 7.

[0036] like Figures 1-4 As shown, the temperature information acquisition module also includes a second temperature sensor 9, which is fixedly connected to the bottom of the support platform 3. The second temperature sensor 9 is communicatively connected to the interactive component 7. Specifically, the second temperature sensor 9 is an infrared temperature sensor. Several through holes are provided through the support platform 3, and a slider is slidably connected to the guide rail 2. A groove is opened on the top surface of the slider, and the second temperature sensor 9 is arranged in a rectangular array on the bottom surface of the groove. The support platform 3 is fixedly connected to the top surface of the slider, and the second temperature sensor 9 corresponds to the through holes, so that the second temperature sensor 9 can detect the temperature of the textile above the support platform 3.

[0037] like Figures 1-3As shown, a photosensitive sensor 10 is fixedly connected to one side of the first temperature sensor 5. Several LED beads 13 are fixedly connected to the top edge of the support platform 3. The LED beads 13 are arranged in a linear array along the length direction of the guide rail 2. The photosensitive sensor 10 is located directly above the moving path of the LED beads 13. The photosensitive sensor 10 is electrically connected to the interactive component 7. Specifically, the LED beads 13 are embedded in the support platform 3. A power supply is fixed on the bottom surface of the groove. The bottom end of the LED beads 13 is electrically connected to the power supply. The photosensitive sensor 10 and the first temperature sensor 5 are installed on the same surface of the first bracket. The position on the support platform 3 detected by the first temperature sensor 5 is determined by the LED beads 13 passing below the photosensitive sensor 10. The photosensitive sensor 10 is located at the extension of the array direction of the first temperature sensor 5.

[0038] like Figure 1 , Figure 4 As shown, the screen printing plate consists of a frame and several metal wires. The heating element 4 is in contact with the metal wires, which are made of aluminum-copper alloy and have a diameter of not less than 0.08 mm. The frame includes an upper frame 11 and a lower frame 12. The upper frame 11 is fixedly connected to the heating element 4, and the lower frame 12 is fixedly connected to the metal wires. The upper frame 11 and the lower frame 12 are detachably connected. Specifically, clamping elements are provided on both sides of the lower frame 12 and the upper frame 11. The clamping elements have a C-shaped cross-section, and a clamping bolt is provided through the top surface of the clamping elements. The lower frame 11... The bottom surface of 2 abuts against the inner wall of the clamping member, the bottom surface of the upper frame 11 abuts against the top surface of the lower frame 12, the top surface of the upper frame 11 abuts against the bottom surface of the clamping bolt, and the mesh made of metal wire is fixed to the lower frame 12. When the upper frame 11 and the lower frame 12 are fixed, the heating element 4 is in contact with the mesh. When the mesh needs to be replaced, the lower frame 12 can be pulled out by loosening the clamping bolt. The aluminum-copper alloy has good thermal conductivity, and the thermal conductivity of the metal wire is improved by increasing the diameter of the metal wire, so as to ensure the heating effect of the heating element 4 on the ink.

[0039] Example 2: A screen printing process using the aforementioned defect detection mechanism, comprising the following steps:

[0040] S1. Preheating: The ink on the screen printing plate is heated by heating component 4;

[0041] S2, Placement: Place the textile on the support platform 3;

[0042] S3. Positioning: The location information of the textile after placement is obtained through camera 6, and the textile is positioned.

[0043] S4. Printing: The carrier table 3 enters the processing area from the inspection area along the guide rail 2, and the ink is pressed down by the scraper to form a pattern on the surface of the textile.

[0044] S5. Collect temperature information. During the process of the carrier platform 3 moving from the processing area to the detection area, the temperature of the textile surface is detected by the first temperature sensor 5, and the temperature difference between each block is recorded.

[0045] S6. Acquire image information. When the carrier platform 3 is completely located in the detection area, acquire image information of the textile surface through the camera 6.

[0046] S7. By comparing the location information of the higher temperature area obtained in S5, the location information of the ink is simulated, and the simulated information is combined with the image information collected in S6 to ensure the accuracy of the ink location information.

[0047] S8 Feedback: Based on the ink position information obtained in S7, the expected ink position is compared to determine the number and location of defects, and then fed back to the operator through the interactive component 7.

[0048] Specifically, heating component 4 is activated first to heat the metal wire and ink. In subsequent stages, heating component 4 maintains this heat to ensure the ink carries sufficient heat when leaving the screen printing plate. This reduces the possibility of ink clogging and facilitates subsequent temperature sensor 5 detection of the ink's position on the textile. When the textile reaches the support platform 3, camera 6 acquires the textile's relative position to the support platform 3. The textile is then fed into the processing area via the support platform 3. The screen printing squeegee extrudes the heated ink from the screen, and the falling ink forms a pattern on the textile. The support platform 3 moves the patterned textile outwards, passing below the first temperature sensor 5. The temperature of the area on the fabric with ink is higher than that of other areas because the location of the ink is determined by the temperature difference. Even if the color difference between the ink and the fabric is not obvious, it does not affect the information collection. When the carrier platform 3 is completely in the detection area, it means that the first temperature sensor 5 has completed the detection of the entire fabric on the carrier platform 3, and generated a thermal image by color marking the temperature difference. At this time, the camera 6 collects the image information of the fabric surface. The thermal image and the image information collected by the camera 6 are processed. By combining the two, the accuracy of judging the ink distribution is improved, so as to find the pattern change defects on the fabric caused by the displacement of the ink position, and finally feed back to the operator through the display screen.

[0049] In S3, the temperature of various parts of the textile is detected by the second temperature sensor 9 to detect whether there is a significant local temperature difference in the textile before printing. Specifically, the second temperature sensor 9 detects the temperature of the textile placed on the carrier stage 3 through the through hole. The temperature of the textile is measured before S4 to avoid significant temperature differences between different areas of the textile before contact with the ink due to external factors, which would cause a difference between the hot area detected by the first temperature sensor 5 and the actual position of the ink.

[0050] In S5, the photosensitive sensor 10 detects the LED bead 13 passing below it to obtain the position of the first temperature sensor 5 relative to the support platform 3. In S3, based on the position of the LED bead 13, the camera 6 determines the accuracy of the textile placement to reduce defects caused by offset during textile printing. Specifically, the photosensitive sensor 10 detects the position of the LED bead 13, and the position of the textile detected by the first temperature sensor 5 is determined based on the position of the LED bead 13, ensuring that the output thermal image accurately corresponds to the textile. At the same time, when placing the textile, the camera 6 determines whether the textile placement is accurate by using the relative position of the LED bead 13 and the textile, thereby ensuring that the printed pattern falls accurately in the desired position during printing.

[0051] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A defect detection mechanism for screen printing, comprising a frame (1) and two guide rails (2) fixedly connected to the top surface of the frame (1), wherein a support platform (3) is slidably connected to the guide rails (2), and the upper part of the frame (1) is divided into a detection area and a processing area along the length direction of the guide rails (2), wherein a screen printing plate is provided in the processing area, characterized in that: The screen printing plate is provided with a heating component (4) for heating ink, and the frame (1) is provided with a temperature information acquisition module, an image acquisition module, and a display module; The temperature information acquisition module includes a first temperature sensor (5), which is located at one end of the detection area near the processing area and is higher than the support platform (3). The image acquisition module includes a camera (6), which is located in the detection area. The camera (6) is higher than the support platform (3) and is located on the side of the first temperature sensor (5) away from the detection area. The display module includes an interactive component (7) and a connecting cable (8). The first temperature sensor (5) and the camera (6) are both connected to the interactive component (7) via the connecting cable (8). During the process of the carrier platform (3) moving from the processing area to the detection area, the temperature of the textile surface is detected by the first temperature sensor (5), and the temperature difference between each block is recorded. When the carrier platform (3) is completely in the detection area, the image information of the textile surface is obtained by the camera (6), and the different temperatures are marked by color to generate thermal images. The thermal images and the image information collected by the camera (6) are processed to improve the accuracy of judging the ink distribution.

2. The defect detection mechanism for screen printing according to claim 1, characterized in that: The temperature information acquisition module also includes a second temperature sensor (9), which is fixedly connected to the bottom of the support platform (3) and is communicatively connected to the interactive component (7).

3. The defect detection mechanism for screen printing according to claim 1, characterized in that: A photosensitive sensor (10) is fixedly connected to one side of the first temperature sensor (5). Several lamp beads (13) are fixedly connected to the top edge of the support platform (3). The lamp beads (13) are arranged in a linear array along the length of the guide rail (2). The photosensitive sensor (10) is located directly above the moving path of the lamp beads (13). The photosensitive sensor (10) is electrically connected to the interactive component (7).

4. The defect detection mechanism for screen printing according to claim 1, characterized in that: The screen printing plate consists of a frame and several metal wires. The heating component (4) is in contact with the metal wires. The metal wires are made of aluminum-copper alloy and the diameter of the metal wires is not less than 0.08 mm.

5. The defect detection mechanism for screen printing according to claim 4, characterized in that: The frame includes an upper frame (11) and a lower frame (12). The upper frame (11) is fixedly connected to the heating component (4), and the lower frame (12) is fixedly connected to the metal wire. The upper frame (11) and the lower frame (12) are detachably connected.

6. A screen printing process using a defect detection mechanism as described in any one of claims 1-5, characterized in that: Includes the following steps: S1. Preheating: The ink on the screen printing plate is heated by the heating component (4); S2, Placement: Place the textile on the support platform (3); S3. Positioning: The location information of the textile after placement is obtained through the camera (6), and the textile is positioned. S4, Printing: The carrier table (3) enters the processing area from the inspection area along the guide rail (2), and the ink is pressed down by the scraper to form a pattern on the surface of the textile. S5. Collect temperature information. During the process of the carrier platform (3) moving from the processing area to the detection area, the temperature of the textile surface is detected by the first temperature sensor (5), and the temperature difference between each block is recorded. S6. Acquire image information. When the carrier platform (3) is completely located in the detection area, acquire image information of the textile surface through the camera (6). S7. By comparing the location information of the higher temperature area obtained in S5, the location information of the ink is simulated, and the simulated information is combined with the image information collected in S6 to ensure the accuracy of the ink location information. S8. Feedback: Based on the ink position information obtained in S7, compare it with the expected ink position to obtain the number and position of defects, and then feed it back to the operator through the interactive component (7).

7. The screen printing process according to claim 6, characterized in that: In S3, the temperature of each part of the textile is detected by the second temperature sensor (9) to detect whether there is a significant local temperature difference in the textile before printing.

8. The screen printing process according to claim 6, characterized in that: In S5, the LED bead (13) passing below the photosensitive sensor (10) is detected by the photosensitive sensor (10) to obtain the position of the first temperature sensor (5) relative to the support platform (3).

9. The screen printing process according to claim 6, characterized in that: In S3, the accuracy of the placement of the textile is determined by the camera (6) based on the position of the LED (13) to reduce the number of defective products caused by offset during textile printing.

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