Machine vision-based adhesive label defect detection device and detection method

Abstract

This invention relates to the field of defect detection technology, and proposes a machine vision-based device and method for detecting defects in self-adhesive labels. It can perform multi-data detection with self-adhesive labels, providing a richer variety of data for easier evaluation and analysis. It can also perform dynamic detection with the movement of self-adhesive labels, resulting in higher detection efficiency and greater practicality. The device includes an installation frame and a dynamic detection structure. The installation frame includes a lifting table, on which a gantry frame and a label receiving / discharging assembly are mounted. The label receiving / discharging assembly contains a roll of labels to be inspected, which passes across the lifting table. The dynamic detection structure includes a lifting frame slidably connected within the gantry frame, and an electric lifting rod is mounted on the gantry frame. The lifting end of the electric lifting rod is connected to the lifting frame, and a pressure detection module is installed between the lifting frame and the lifting end of the electric lifting rod. A prism is rotatably connected to the lifting frame, and a first servo motor is mounted on the lifting frame.

Description

Technical Field

[0001] This invention relates to the field of self-adhesive label defect detection technology, specifically to a self-adhesive label defect detection device and method based on machine vision. Background Technology

[0002] As is well known, machine vision-based self-adhesive label defect detection devices are industrial inspection equipment that automatically identifies defects such as label damage, missing prints, and misalignment by relying on visual acquisition and intelligent analysis technology. Machine vision-based self-adhesive label defect detection methods are specific detection methods formed in conjunction with machine vision-based self-adhesive label defect detection devices.

[0003] A search revealed that Chinese patent application number CN202311824280.3 discloses a machine vision-based label defect detection method, which is roughly described as follows: The method includes acquiring a label image of the label to be detected and preprocessing the label image; extracting contours from the target label image and a pre-acquired target template image; performing preliminary matching between the contour of the label to be detected and each template label contour in the template label contour set; classifying the label contours to be detected in the template label contour set; performing refined matching between the label contour to be refined and the corresponding set of matching contours; and generating label defect information corresponding to the label to be detected. Chinese patent application number CN202310628586.5 discloses a machine vision-based method for detecting defects in cylindrical joints, mainly including the following steps: S1: image acquisition based on a single camera; S2: feature extraction and labeling of the image; S3: editing the extracted features into a dataset; S4: target detection; S5: creating an image model; S6: improving training parameters; S7: training the model; S8: defect detection based on templates.

[0004] While both of the aforementioned existing technical solutions can perform target detection operations based on machine vision, both solutions only briefly describe image acquisition of the target object without specifying a concrete method for acquisition. This lack of specific image acquisition techniques for self-adhesive labels is a significant deficiency. Furthermore, in the actual comparison, a... Figure 1 The comparison format involves a massive amount of image processing, which significantly increases the hardware requirements for information processing and necessitates further improvements in detection efficiency. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a machine vision-based device and method for detecting defects in self-adhesive labels. The device, designed for machine vision-based defect detection, enables continuous and rapid image acquisition of self-adhesive labels. After acquisition, it allows for stacked processing of image data, enabling the detection of multiple self-adhesive label images in a single process. This optimizes data processing volume and improves processing efficiency.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a machine vision-based self-adhesive label defect detection device, comprising an installation frame and a dynamic detection structure. The installation frame includes a lifting table, on which a gantry frame and a label receiving / discharging assembly are mounted. A roll of labels to be inspected is installed within the label receiving / discharging assembly, and the roll of labels to be inspected passes across the lifting table. The dynamic detection structure includes a lifting frame, which is slidably connected within the gantry frame. An electric lifting rod is mounted on the gantry frame, and the lifting end of the electric lifting rod is connected to the lifting frame. A pressure detection module is installed between the lifting frame and the lifting end of the electric lifting rod. A prism is rotatably connected to the lifting frame, and a first... A servo motor is provided to drive the rotation of the prism relative to the lifting frame. Multiple detection wheels are slidably connected to the prism, and each detection wheel is equipped with an adjustment mechanism. The adjustment mechanisms are mounted on the lifting frame. Each detection wheel has an annular side groove, and each annular side groove contains a detection frame. Each detection frame is connected to the adjustment mechanism. The bottom of each detection frame has a horizontal surface, and a central camera and two side light rangefinders are mounted on each horizontal surface. The detection wheels are made of transparent material. A grating ruler is mounted on the lifting frame, and an auxiliary bracket is mounted on the detection end of the grating ruler. The bottom end of the auxiliary bracket matches the top surface of the lifting table.

[0007] Preferably, the pressure detection module includes a mounting cylinder and an insertion frame. The mounting cylinder is fixedly connected to the bottom end of the lifting end of the electric lifting rod, and the insertion frame is fixedly connected to the top end of the lifting frame. The insertion frame is slidably connected to the mounting cylinder. A pressure sensor is installed inside the mounting cylinder. A pressure spring is fixedly connected to the top end of the insertion frame. The top end of the pressure spring is fixedly connected inside the mounting cylinder, and a central plate is fixedly connected inside the pressure spring. The central plate is used for contact pressure application of the pressure sensor.

[0008] Preferably, the mounting cylinder has a side lead hole, through which the external data cable of the pressure sensor extends.

[0009] Preferably, the adjustment mechanism includes a rack and a plurality of movable frames. The rack is fixedly connected to the top of the lifting frame. A central groove is provided at the top of the lifting frame. The plurality of movable frames are slidably connected in the central groove. A second servo motor is installed on each of the movable frames. A drive gear is installed on the output shaft of each of the second servo motors. The drive gears mesh with the rack. A plurality of detection frames are fixedly connected to the plurality of movable frames. An arc-shaped frame is connected to each of the movable frames. A first limiting ring and a second limiting ring are fixedly connected in each of the plurality of detection wheels. The first limiting rings are matched with the arc-shaped frames, and the second limiting rings are matched with the arc-shaped frames.

[0010] Preferably, each of the multiple movable frames is provided with a suspension support, and each of the multiple suspension supports is provided with an embedding groove. The multiple arc-shaped frames are slidably connected in the multiple embedding grooves, and each of the multiple suspension supports is provided with a threaded hole. The multiple threaded holes are respectively connected to the multiple embedding grooves, and each of the multiple threaded holes is threaded with a threaded rod. The multiple threaded rods are respectively rotatably connected to the multiple arc-shaped frames.

[0011] Preferably, the label receiving and discharging assembly includes two rotating seats, which are respectively fixedly connected to both ends of the lifting table. The two rotating seats are rotatably connected to an unwinding frame and a winding frame, respectively. A fine-adjusting spring is fixedly connected to both the unwinding frame and the winding frame. The two fine-adjusting springs are respectively fixedly connected to the two rotating seats. An unwinding shaft and a winding shaft are rotatably connected inside the unwinding frame and the winding frame, respectively. An obstructing friction element and a third servo motor are respectively installed outside the unwinding frame and the winding frame. The third servo motor is used to drive the rotation of the winding shaft, and the obstructing friction element is used to obstruct the rotation of the unwinding shaft.

[0012] Preferably, the friction-blocking component includes an external mounting frame and a rotating friction head. The external mounting frame is fixedly connected to the uncoiling frame, and the rotating friction head is fixedly connected to the uncoiling shaft. An internally threaded cylinder is fixedly connected to the external mounting frame. A screw is internally threadedly connected to the internally threaded cylinder. A compression spring is fixedly connected to the screw. A friction pressure plate is rotatably connected to the compression spring. The friction pressure plate matches the rotating friction head. A rotation limit rod is fixedly connected to the friction pressure plate. A guide sleeve is slidably connected to the rotation limit rod. The guide sleeve is fixedly connected to the internally threaded cylinder.

[0013] Preferably, two rails are fixedly connected to the lifting table, and two rail grooves are opened at the bottom of the gantry frame. The two rails are slidably engaged in the two rail grooves respectively. A limit pin is detachably provided on the gantry frame, and multiple auxiliary insertion holes matching the limit pin are opened on one of the two rails.

[0014] Preferably, the bottom end of the auxiliary support is provided with a wheel groove, and a supporting rolling wheel is rotatably connected in the wheel groove. The central camera, which is installed on the same horizontal plane, is located between the two side light rangefinders.

[0015] A machine vision-based method for detecting defects in self-adhesive labels includes the following steps:

[0016] S1. Before measurement, first equip the label take-up and drop-off assembly, electric lifting rod, grating ruler, pressure detection module, first servo motor, adjustment mechanism, central camera and two side light rangefinders with a control computer. Through the control computer, the operation control of the label take-up and drop-off assembly, electric lifting rod, first servo motor and adjustment mechanism can be realized. At the same time, the detection data of the grating ruler, pressure detection module, central camera and two side light rangefinders can be read, stored and displayed. The grating ruler is adjusted. When the label roll to be tested is not installed, the value of the grating ruler when the bottom end of the auxiliary support and the top surface of the lifting table form a support match is recorded, and this value is marked as the initial value of the grating ruler.

[0017] S2. During measurement, first turn on the power to the control computer, label take-up and drop assembly, electric lifting rod, grating ruler, pressure detection module, first servo motor, adjustment mechanism, central camera and two side light rangefinders. Then, install the label roll to be tested into the label take-up and drop assembly. The label take-up and drop assembly enables the label roll to be tested to slide flat on the lifting table. As the label roll to be tested slides flat on the lifting table, the first servo motor is started to drive the rotation of the prism shaft. The circumferential linear velocity of the detection wheel on the prism shaft is controlled to be consistent with the speed of the label roll to be tested passing through the lifting table. The electric lifting rod is used to adjust the relative position of the lifting frame within the gantry, thereby achieving relative position control of the detection wheel relative to the label roll to be tested.

[0018] S3. During the operation of the detection wheel, when the detection wheel is in a suspended state without contacting the label roll to be tested, the detection pressure reading of the pressure detection module is stable at a fixed reading. However, when the detection wheel comes into contact with the self-adhesive label and forms an interaction force, the reading of the pressure detection module will change. During the relative descent of the detection wheel, the grating ruler will form a real-time detection of the height change of the detection wheel. When the reading of the pressure detection module changes, the electric lifting rod will maintain the current working position and stop. Since the circumferential linear velocity of the detection wheel is the same as the speed of the label roll to be tested passing through the lifting table, the detection wheel will form a rolling operation relative to the label roll to be tested. The relative frictional displacement of the contact area between the two can be ignored.

[0019] S4. The control computer records the final detection value of the grating ruler. At the same time, the central camera detects the relative distance between the label roll to be tested pressed down directly under the detection wheel and the central camera. The two side light rangefinders detect the relative distance between the label roll to be tested before and after being pressed down and the side light rangefinders, respectively. The control computer records the detection data of the side light rangefinders and the central camera, and combines the recorded data to form data analysis.

[0020] S5. During data analysis, the final measured value of the grating ruler is subtracted from its initial value to obtain the relative distance between the bottom of the detection wheel and the lifting table. This distance represents the thickness of the label roll being tested when the detection wheel is pressed down. Subtracting the data of the label roll not yet pressed down by the detection wheel from the data detected by the central camera from the data detected by the edge light rangefinder gives the pressing distance of the detection wheel on the label roll. Adding this pressing distance to the thickness of the label roll after being pressed down by the detection wheel gives the natural thickness of the label roll when it is not pressed down by the detection wheel. By comparing the difference between the data of the label roll already pressed down by the detection wheel detected by the edge light rangefinder and the data detected by the central camera, the elastic recovery of the label roll can be evaluated.

[0021] S6. When analyzing and processing the self-adhesive label image information acquired by the camera, the images of multiple self-adhesive labels acquired in the order of delivery are semi-transparent one by one. Then, the processed images are superimposed and overlapped in sequence. The composite image is visually compared and analyzed. If the overlap of the multiple label images is high and the overall outline of the self-adhesive labels in the superimposed image is regular and clear, it indicates that the corresponding self-adhesive labels have no obvious defects. If the edge boundaries of the self-adhesive labels in the superimposed composite image are blurred, the outline is misaligned, or there is abnormal local overlap, it is determined that the corresponding self-adhesive labels in this batch have quality defects such as printing deviation, irregular size, or edge damage. Then, the multiple superimposed images are further screened to identify the corresponding defective self-adhesive labels.

[0022] Compared with existing technologies, the present invention provides a machine vision-based device and method for detecting defects in self-adhesive labels, which has the following advantages:

[0023] (1) In this invention, through the design of the dynamic detection structure, not only can it be matched with the label roll to be tested to form a corresponding measurement function component, but it can also be matched with the label roll to be tested to form multiple data detection, with a rich variety of detection data, which makes it more convenient for the evaluation and analysis of the label.

[0024] (2) In this invention, the design of the mounting frame facilitates the corresponding installation of the dynamic detection structure and also facilitates the installation of the label take-up and take-down components, thereby enabling the unwinding and rewinding of rolled labels to facilitate the movement and detection of the label roll to be detected in conjunction with the dynamic detection structure, and the detection efficiency is further improved.

[0025] (3) In this invention, by equipping a pressure detection module, the relative force between the electric lifting rod and the lifting frame can be detected and quantified, and finally the downward pressure of the detection wheel relative to the label roll to be tested can be detected, so as to facilitate the determination of the detection status of the label roll to be tested.

[0026] (4) In this invention, by equipping the adjustment mechanism, the detection wheel can be driven to adjust laterally along the prism axis, thereby achieving the lateral position adjustment of the detection wheel relative to the label roll to be detected, and also providing the necessary mounting position for the central camera and the two side light rangefinders. Attached Figure Description

[0027] Figure 1 This is a three-dimensional structural diagram of the entire invention;

[0028] Figure 2 For the present invention Figure 1 A magnified schematic diagram of the partial structure at point A in the middle;

[0029] Figure 3 For the present invention Figure 1 A magnified schematic diagram of the local structure at point B;

[0030] Figure 4 This is a three-dimensional structural diagram of the detection frame, moving frame, and second servo motor of the present invention.

[0031] Figure 5 This is a three-dimensional structural diagram of the interaction between the movable frame and the suspension support of the present invention;

[0032] Figure 6 This is a three-dimensional structural diagram showing the assembly of the connecting seat, unwinding frame, and unwinding shaft of the present invention.

[0033] Figure 7 This is a three-dimensional structural diagram of the entire invention from another angle;

[0034] Figure 8 For the present invention Figure 7 A magnified schematic diagram of the local structure at point C;

[0035] Figure 9 This is a three-dimensional structural diagram of the gantry frame, lifting frame, and electric lifting rod of the present invention.

[0036] Figure 10This is a three-dimensional structural diagram showing the assembly of the screw, compression spring, and friction plate of the present invention.

[0037] Figure 11 This is a three-dimensional structural diagram of the detection wheel, the first limiting ring, and the second limiting ring of the present invention.

[0038] Figure 12 This is a three-dimensional structural diagram of the invention viewed from below.

[0039] Figure 13 For the present invention Figure 12 A magnified schematic diagram of the local structure at point D;

[0040] Figure 14 This is a three-dimensional structural diagram of the gantry frame, electric lifting rod, and detection wheels of the present invention.

[0041] Figure 15 For the present invention Figure 14 A magnified schematic diagram of the local structure at point E;

[0042] Figure 16 This is a bottom-view three-dimensional structural diagram of the detection frame, moving frame, and second servo motor of the present invention.

[0043] In the diagram: 1. Lifting table; 2. Gantry frame; 3. Label roll to be inspected; 4. Lifting frame; 5. Electric lifting rod; 6. Prism shaft; 7. First servo motor; 8. Inspection wheel; 9. Annular side groove; 10. Inspection frame; 11. Horizontal plane; 12. Center camera; 13. Side light rangefinder; 14. Grating ruler; 15. Auxiliary support; 16. Mounting cylinder; 17. Insertion frame; 18. Pressure sensor; 19. Compression spring; 20. Center plate; 21. Side lead hole; 22. Straight rack; 23. Moving frame; 24. Center groove; 25. Second servo motor; 26. Drive gear; 27. Arc-shaped frame; 28. First limiting ring; 29. ​​Second limiting ring; 30. Suspension support; 31. Embedded groove; 32. Threaded rod; 33. Rotary connecting seat; 34. Uncoiling frame; 35. Winding frame; 36. Fine-tuning spring; 37. Uncoiling shaft; 38. Winding shaft; 39. Third servo motor; 40. External assembly frame; 41. Rotating friction head; 42. Internal threaded cylinder; 43. Screw; 44. Compression spring; 45. Friction pressure plate; 46. Rotating limiting rod; 47. Guide sleeve; 48. Track bar; 49. Track groove; 50. Limiting pin; 51. Auxiliary insertion hole; 52. Support roller. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] For examples, please refer to Figures 1-16 A machine vision-based self-adhesive label defect detection device includes a mounting frame and a dynamic detection structure. The mounting frame includes a lifting table 1, on which a gantry frame 2 and a label take-up and drop-down assembly are mounted. A label roll 3 to be inspected is installed inside the label take-up and drop-down assembly, spanning across the lifting table 1. The label take-up and drop-down assembly includes two rotating seats 33, which are fixedly connected to both ends of the lifting table 1. An uncoiling frame 34 and a winding frame 35 are rotatably connected to the two rotating seats 33. Fine-adjusting springs 36 are fixedly connected to both the uncoiling frame 34 and the winding frame 35, respectively. An uncoiling shaft 37 and a winding shaft 38 are rotatably connected inside the uncoiling frame 34 and the winding frame 35, respectively. Friction-resistant components and a third servo motor 39 are mounted outside the uncoiling frame 34 and the winding frame 35, respectively. The third servo motor 39 drives the rotation of the winding shaft 38. The rotational obstruction for the unwinding shaft 37 includes an external mounting frame 40 and a rotating friction head 41. The external mounting frame 40 is fixedly connected to the unwinding frame 34, and the rotating friction head 41 is fixedly connected to the unwinding shaft 37. An internally threaded cylinder 42 is fixedly connected to the external mounting frame 40. A screw 43 is internally threaded to the internally threaded cylinder 42. A compression spring 44 is fixedly connected to the screw 43. A friction pressure plate 45 is rotatably connected to the compression spring 44. The friction pressure plate 45 matches the rotating friction head 41. A rotational limit rod 46 is fixedly connected to the friction pressure plate 45. A guide sleeve 47 is slidably connected to the rotational limit rod 46. The guide sleeve 47 is fixedly connected to the internally threaded cylinder 42. The design of the mounting frame facilitates the corresponding installation of the dynamic detection structure and the label take-up and unwinding components. This enables the unwinding and rewinding of rolled labels, facilitating the movement and detection of the label roll 3 to be inspected in conjunction with the dynamic detection structure, thus further improving the detection efficiency.

[0046] It should be further explained that the dynamic detection structure includes a lifting frame 4, which is slidably connected within the gantry frame 2. An electric lifting rod 5 is installed on the gantry frame 2. The lifting end of the electric lifting rod 5 is connected to the lifting frame 4. A pressure detection module is installed between the lifting frame 4 and the lifting end of the electric lifting rod 5. The pressure detection module includes an installation cylinder 16 and an insertion frame 17. The installation cylinder 16 is fixedly connected to the bottom end of the lifting end of the electric lifting rod 5. The insertion frame 17 is fixedly connected to the top end of the lifting frame 4 and is slidably connected to the installation cylinder 16. A pressure sensor 18 is installed inside the installation cylinder 16. A pressure spring 19 is fixedly connected to the top end of the insertion frame 17. The top end of the pressure spring 19 is fixedly connected inside the installation cylinder 16, and the pressure spring 19 is fixedly... A central plate 20 is fixedly connected, which is used for contact pressure application of the pressure sensor 18. With the addition of a pressure detection module, the relative force between the electric lifting rod 5 and the lifting frame 4 can be detected and quantified, ultimately detecting the downward pressure of the detection wheel 8 relative to the label roll 3 to be tested, thus facilitating the determination of the detection status of the label roll 3. A side lead hole 21 is provided on the mounting cylinder 16, through which the external data cable of the pressure sensor 18 extends, facilitating signal connection with the control computer and electrical connection with external power lines. A prism shaft 6 is rotatably connected to the lifting frame 4, and a first servo motor 7 is mounted on the lifting frame 4. The first servo motor 7 drives the rotation of the prism shaft 6 relative to the lifting frame 4. Multiple detection wheels 8 are slidably connected to shaft 6. Each detection wheel 8 is equipped with an adjustment mechanism, which is mounted on lifting frame 4. The adjustment mechanism includes a rack 22 and multiple movable frames 23. The rack 22 is fixedly connected to the top of lifting frame 4. A central groove 24 is provided at the top of lifting frame 4. Multiple movable frames 23 are slidably connected within the central groove 24. A second servo motor 25 is mounted on each of the movable frames 23. A drive gear 26 is mounted on the output shaft of each of the second servo motors 25. The drive gears 26 mesh with the rack 22. Multiple detection frames 10 are fixedly connected to the multiple movable frames 23 respectively. Each movable frame 23 is connected to an arc-shaped frame 27. A first limiting ring 2 is fixedly connected within each of the multiple detection wheels 8. 8. The second limiting ring 29, multiple first limiting rings 28 are respectively matched with multiple arc-shaped frames 27, and multiple second limiting rings 29 are also respectively matched with multiple arc-shaped frames 27. Multiple movable frames 23 are provided with suspension supports 30, and multiple suspension supports 30 are respectively provided with embedding grooves 31. Multiple arc-shaped frames 27 are respectively slidably connected in multiple embedding grooves 31, and multiple suspension supports 30 are respectively provided with threaded holes, multiple threaded holes are respectively connected to multiple embedding grooves 31, and multiple threaded rods 32 are respectively rotatably connected to multiple arc-shaped frames 27. With the configuration of the adjustment mechanism, the detection wheel 8 can be driven to adjust laterally along the prism axis 6, thereby achieving the lateral position adjustment of the detection wheel 8 relative to the label roll 3 to be detected.It also provides the necessary mounting locations for the central camera 12 and the two side-mounted light rangefinders 13.

[0047] Furthermore, each of the multiple detection wheels 8 is equipped with annular side grooves 9, and each of the multiple annular side grooves 9 is equipped with a detection frame 10. The multiple detection frames 10 are connected to multiple adjustment mechanisms. The bottom of each of the multiple detection frames 10 is provided with a horizontal surface 11. A central camera 12 and two side-beam distance meters 13 are mounted on each of the multiple horizontal surfaces 11. The central camera 12, mounted on the same horizontal surface 11, is located between the two side-beam distance meters 13. All of the multiple detection wheels 8 are made of transparent material. A grating ruler 14 is mounted on the lifting frame 4. An auxiliary support 15 is mounted on the detection end of the grating ruler 14. The bottom end of the auxiliary support 15 matches the top surface of the lifting table 1. A wheel groove is formed at the bottom end of the auxiliary support 15, and a supporting roller 52 is rotatably connected within the wheel groove. Through the design of the dynamic detection structure, it can not only form a corresponding measurement function component with the label roll 3 to be tested, but also form multiple data detection with the label roll 3 to be tested. The detection data is relatively rich and more convenient for the evaluation and analysis of self-adhesive labels. Two rails 48 are fixedly connected on the lifting table 1. Two rail grooves 49 are opened at the bottom of the gantry 2. The two rails 48 are slidably fitted in the two rail grooves 49 respectively. A limit pin 50 is detachably installed on the gantry 2. One of the two rails 48 has multiple auxiliary insertion holes 51 that match the limit pin 50, which facilitates the position adjustment of the gantry 2 on the lifting table 1 and also facilitates the limiting of the gantry 2 after the relative position adjustment on the lifting table 1.

[0048] In this embodiment, the electric lifting rod 5, the first servo motor 7, the central camera 12, the side light rangefinder 13, the grating ruler 14, the pressure sensor 18, the second servo motor 25, and the third servo motor 39 are all commercially available conventional devices known to those skilled in the art. In this invention, we are simply using them without modifying their structure or function. Their setting method, installation method, and electrical connection method can be easily understood by those skilled in the art by following the instructions for use, and will not be described in detail here.

[0049] In summary, the working principle of this machine vision-based self-adhesive label defect detection device is as follows: Before formally commencing detection and measurement work, a control computer is uniformly equipped and installed on the label receiving and discharging assembly, electric lifting rod 5, grating ruler 14, pressure detection module, first servo motor 7, adjustment mechanism, central camera 12, and two edge light rangefinders 13. Through this control computer, not only can precise operation control of the label receiving and discharging assembly, electric lifting rod 5, first servo motor 7, and adjustment mechanism be achieved, ensuring the coordinated operation of each component, but also the grating ruler 14 can be monitored. The system enables real-time reading, storage, and display of various detection data collected by the pressure detection module, the central camera 12, and the two side light rangefinders 13, providing reliable data support for subsequent data processing and analysis. Subsequently, the grating ruler 14 is calibrated and adjusted. Without the label roll 3 to be tested installed, the specific value of the grating ruler 14 is recorded when the bottom end of the auxiliary support 15 forms a stable support match with the top surface of the lifting table 1. This value is marked as the initial reference value of the grating ruler 14, providing a reference standard for height measurement in the subsequent testing process. When entering the actual measurement stage, the system first connects... Power is supplied to the control computer, label take-up and drop assembly, electric lifting rod 5, grating ruler 14, pressure detection module, first servo motor 7, adjustment mechanism, central camera 12, and two side light rangefinders 13 to ensure all components are in normal working condition. Then, the label roll 3 to be tested is installed into the label take-up and drop assembly. Through the coordinated operation of the label take-up and drop assembly, the label roll 3 to be tested can smoothly slide across the lifting table 1, laying the foundation for subsequent continuous testing. As the label roll 3 to be tested smoothly slides across the lifting table 1, the first servo motor 7 is started. The rotation drive of the prism shaft 6 is achieved by the first servo motor 7, which strictly controls the circumferential linear velocity of the detection wheel 8 on the prism shaft 6, so that its circumferential linear velocity is consistent with the speed of the label roll 3 to be tested passing through the lifting table 1. This avoids damage to the label to be tested or affect the detection accuracy due to relative frictional displacement caused by the speed difference between the two. At the same time, the operation of the electric lifting rod 5 realizes the vertical relative position adjustment of the lifting frame 4 within the gantry 2, thereby accurately controlling the vertical relative position of the detection wheel 8 relative to the label roll 3 to be tested, ensuring that the detection wheel 8 can form a suitable contact state with the label roll 3 to be tested.

[0050] During the operation of the detection wheel 8, when it is suspended and not in contact with the label roll 3 to be tested, the pressure reading of the pressure detection module remains stable at a fixed value. However, when the detection wheel 8 descends and comes into contact with the label roll 3 to be tested, forming an interaction force, the reading of the pressure detection module changes immediately and significantly. Throughout the relative descent of the detection wheel 8, the grating ruler 14 detects the height change of the detection wheel 8 in real time and provides feedback data. When the reading of the pressure detection module reaches the preset value, the electric lifting rod 5 immediately maintains its current working position and stops. Since the circumferential linear velocity of the detection wheel 8 is exactly the same as the speed of the label roll 3 to be tested passing through the lifting table 1, the detection wheel 8 will form a smooth rolling operation relative to the label roll 3 to be tested. The relative frictional displacement at the contact point between the two is negligible, which ensures the stability of the detection and avoids damage to the self-adhesive label. Furthermore, the control computer records the final detection value of the grating ruler 14 in real time. At the same time, the central camera 12 installed on the horizontal plane 11 of the detection frame 10 will detect the area directly below the detection wheel 8. The pressed label roll 3 is photographed and sampled. Two edge light rangefinders 13 respectively detect the relative distance between the label roll 3 that has not yet been pressed by the detection wheel 8 and the corresponding edge light rangefinder 13. The control computer records all detection data collected by the edge light rangefinder 13 and the central camera 12 in real time, and combines it with the previously recorded data of the grating ruler 14 and pressure detection data to form a complete data analysis system. During the data analysis process, the final detection value of the grating ruler 14 is compared with the grating ruler 14 recorded during the debugging stage. 4. Subtract the initial values ​​to obtain the relative distance between the bottom of the detection wheel 8 and the lifting table 1. This distance is the actual thickness of the label roll 3 under test when it is pressed down by the detection wheel 8. By comparing the difference between the data detected by the two side light rangefinders 13 on both sides of the central camera 12 that have not been pressed by the detection wheel 8 and the data that have been pressed by the detection wheel 8 with the data detected in the previous step, the elastic deformation degree and elastic recovery performance of the label roll 3 under test after being pressed can be effectively evaluated, and it can be determined whether it meets the quality standards.

[0051] It should be noted that the core electrical components of the pressure detection module, the label take-up and drop assembly, and the adjustment mechanism are the pressure sensor 18, the third servo motor 39, and the second servo motor 25, respectively. These electrical components are all electrically connected to the control computer, receiving instructions from the control computer and feeding back operating data. During operation, when the detection wheel 8 is suspended, the mounting cylinder 16 and the insertion frame 17 are in a relatively pulled-out limit state due to the weight of the lifting frame 4 and the elasticity of the pressure spring 19. At this time, the pressure spring 19 is under relatively small compression, and the pressure exerted by the central plate 20 on the pressure sensor 18 is also small, resulting in a low detection value for the pressure sensor 18. However, when the detection wheel 8 forms vertical support with the label roll 3 to be detected and generates a certain vertical interaction force, the detection wheel 8 tends to lift upwards relative to the gantry 2 under this force, which in turn causes the pressure spring 19 to further compress, leading to an increase in the pressure of the central plate 20 relative to the pressure sensor 18. The detection value of sensor 18 also increases accordingly. According to the actual detection needs, the staff can set the increase in the detection value of pressure sensor 18 to achieve precise control of the downward pressure of detection wheel 8 relative to the label roll 3 to be tested, ensuring the stability of the detection process and the accuracy of the detection results. After the second servo motor 25 of the adjustment mechanism is powered on, it can drive the rotation of drive gear 26. Under the mutual meshing transmission of drive gear 26 and rack 22, it can drive the moving frame 23 to move smoothly relative to the middle groove 24 on the lifting frame 4, thereby realizing the relative position adjustment of moving frame 23 relative to lifting frame 4. Finally, it drives detection wheel 8 to slide relative to the prism 6 in the lifting frame 4, so that detection wheel 8 can realize flexible adjustment of longitudinal relative position according to the specifications of label roll 3 to be tested and the detection requirements, expand the detection coverage, and improve the comprehensiveness of label full-area detection. At the same time, according to the distance pressed by the rotating roller of detection wheel 8, the length of label roll 3 to be tested can also be detected simultaneously, expanding the detection function of the device.

[0052] When installing the rolled label roll 3 to be tested into the label take-up and unwinding assembly, simply adjust the relative position of the rolled label roll 3 to be tested and the unwinding shaft 37 so that the unwinding shaft 37 is inserted into the center of the rolled label roll 3, ensuring that there is a certain degree of rotational freedom between the unwinding shaft 37 and the rolled label roll 3. If necessary, external rods can be used to create a support and positioning between the unwinding shaft 37 and the rolled label roll 3 to prevent the self-adhesive label roll from shifting during operation. Then, the self-adhesive label head of the rolled label roll 3 is passed through the space between the detection wheel 8 and the lifting table 1 and wound onto the winding shaft 38. The third servo motor 39 is then started, and the third servo motor 39 is used to achieve... The rotation drive of the winding shaft 38 enables the continuous winding of the label roll 3 to be inspected relative to the winding shaft 38, thereby driving the label roll 3 to be inspected to pass smoothly and continuously through the lifting table 1. This ensures the continuous inspection of the label roll 3 by the inspection wheel 8. In addition, by the cooperation between the friction plate 45 in the friction component and the rotating friction head 41, a stable rotational damping force can be provided to the rotating unwinding shaft 37. This effectively improves the flatness and tension of the label roll 3 as it winds the label roll 3 through the lifting table 1, preventing wrinkles or misalignment of the labels and ensuring that the inspection wheel 8 can carry out inspection operations normally. To improve the accuracy and efficiency of obstacle detection data, when analyzing and processing the self-adhesive label image information acquired by the central camera 12, the images of multiple self-adhesive labels acquired sequentially in the transport order are semi-transparent one by one. This means that multiple self-adhesive labels are controlled to sequentially pass under the central camera 12, and the central camera 12 takes a picture of each passing label. Each picture displays an image of one self-adhesive label, and multiple images are semi-transparent one by one. The degree of transparency can be selected according to the number of superimposed images. If the number of superimposed images is small, the degree of transparency is low; if the number of superimposed images is large, the degree of transparency is high. The images are processed to a high degree. Then, the processed images are superimposed one by one, and the composite image is visually compared and analyzed. If the superimposed images have a high degree of overlap and the overall outline of the self-adhesive labels in the superimposed image is regular and clear, it indicates that the corresponding self-adhesive labels have no obvious defects, and the inspection of this batch is completed. If the edges of the self-adhesive labels in the superimposed composite image are blurred, the outline is misaligned, or there is abnormal local overlap, it is determined that the corresponding self-adhesive labels in this batch may have quality defects such as printing deviation, irregular size, or edge damage. Then, the superimposed images are screened one by one to identify the corresponding defective self-adhesive labels, thus completing the defect detection operation.

[0053] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A machine vision-based self-adhesive label defect detection device, comprising a mounting frame, characterized in that, It also includes a dynamic detection structure. The mounting frame includes a lifting table, on which a gantry frame and a label receiving / discharging assembly are mounted. A roll of labels to be tested is installed within the label receiving / discharging assembly and passes across the lifting table. The dynamic detection structure includes a lifting frame slidably connected within the gantry frame, and an electric lifting rod is mounted on the gantry frame. The lifting end of the electric lifting rod is connected to the lifting frame, and a pressure detection module is installed between the lifting frame and the lifting end of the electric lifting rod. A prism is rotatably connected to the lifting frame, and a first servo motor is mounted on the lifting frame. The first servo motor is used to control the prism relative to... The lifting frame is driven by a rotating shaft with multiple detection wheels slidably connected to it. Each detection wheel is equipped with an adjustment mechanism, which is mounted on the lifting frame. Each detection wheel has an annular side groove, and each annular side groove contains a detection frame. Each detection frame is connected to the adjustment mechanism. The bottom of each detection frame has a horizontal surface, and a central camera and two side light rangefinders are mounted on each horizontal surface. The detection wheels are made of transparent material. A grating ruler is mounted on the lifting frame, and an auxiliary support is mounted on the detection end of the grating ruler. The bottom end of the auxiliary support matches the top surface of the lifting table. When the detection wheel is suspended and not in contact with the label roll to be tested, the pressure reading of the pressure detection module remains stable at a fixed value. However, when the detection wheel descends and comes into contact with the label roll to be tested, forming an interaction force, the reading of the pressure detection module will immediately change significantly. Throughout the relative descent of the detection wheel, the grating ruler will detect the height change of the detection wheel in real time and provide feedback data. When the pressure reading of the pressure detection module reaches the preset value, the electric lifting rod will immediately maintain its current working position and stop, recording the final detection value of the grating ruler in real time. The central camera installed on the horizontal plane of the detection frame will take pictures of the label roll to be tested directly under the detection wheel. The two side light rangefinders will respectively detect the label roll that has not yet been pressed by the detection wheel and the label roll that has been pressed by the detection wheel. The relative distance between the label roll to be tested pressed by the detection wheel and the corresponding edge light rangefinder, combined with the previously recorded grating ruler data and pressure detection data, forms a complete data analysis system. During the data analysis process, the final detection value of the grating ruler is subtracted from the initial value of the grating ruler recorded during the debugging stage. The result is the relative distance between the bottom of the detection wheel and the lifting table. This distance is the actual thickness of the label roll to be tested when it is pressed down by the detection wheel. By comparing the difference between the data detected by the two edge light rangefinders on both sides of the central camera that have not yet been pressed by the detection wheel and the data that have been pressed by the detection wheel with the data detected in the previous step, the degree of elastic deformation and elastic recovery performance of the label roll to be tested after being compressed can be effectively evaluated.

2. The machine vision-based self-adhesive label defect detection device according to claim 1, characterized in that, The pressure detection module includes a mounting cylinder and an insertion frame. The mounting cylinder is fixedly connected to the bottom end of the lifting end of the electric lifting rod, and the insertion frame is fixedly connected to the top end of the lifting frame. The insertion frame is slidably connected to the mounting cylinder. A pressure sensor is installed inside the mounting cylinder. A pressure spring is fixedly connected to the top end of the insertion frame. The top end of the pressure spring is fixedly connected inside the mounting cylinder, and a central plate is fixedly connected inside the pressure spring. The central plate is used for contact pressure application of the pressure sensor.

3. The machine vision-based self-adhesive label defect detection device according to claim 2, characterized in that, The mounting cylinder has a side lead hole, through which the external data cable of the pressure sensor extends.

4. The machine vision-based self-adhesive label defect detection device according to claim 3, characterized in that, The adjustment mechanism includes a rack and multiple movable frames. The rack is fixedly connected to the top of the lifting frame. A central slot is provided at the top of the lifting frame. The multiple movable frames are slidably connected within the central slot. A second servo motor is mounted on each of the multiple movable frames. A drive gear is mounted on the output shaft of each of the multiple second servo motors. The multiple drive gears mesh with the rack. Multiple detection frames are fixedly connected to the multiple movable frames respectively. Each of the multiple movable frames is connected to an arc-shaped frame. A first limiting ring and a second limiting ring are fixedly connected within each of the multiple detection wheels. The multiple first limiting rings are matched with the multiple arc-shaped frames respectively, and the multiple second limiting rings are also matched with the multiple arc-shaped frames respectively.

5. The machine vision-based self-adhesive label defect detection device according to claim 4, characterized in that, Each of the multiple movable frames is provided with a suspension support, and each of the multiple suspension supports is provided with an embedding groove. Each of the multiple arc-shaped frames is slidably connected in the multiple embedding grooves. Each of the multiple suspension supports is provided with a threaded hole, and each of the multiple threaded holes is connected with a threaded rod. Each of the multiple threaded rods is rotatably connected to the multiple arc-shaped frames.

6. The machine vision-based self-adhesive label defect detection device according to claim 5, characterized in that, The label take-up and take-down assembly includes two rotating seats, which are fixedly connected to both ends of the lifting table. An uncoiling frame and a winding frame are rotatably connected to the two rotating seats. A fine-adjusting spring is fixedly connected to both the uncoiling frame and the winding frame. The two fine-adjusting springs are fixedly connected to the two rotating seats. An uncoiling shaft and a winding shaft are rotatably connected inside the uncoiling frame and the winding frame, respectively. An obstructing friction component and a third servo motor are installed outside the uncoiling frame and the winding frame, respectively. The third servo motor is used to drive the rotation of the winding shaft, and the obstructing friction component is used to obstruct the rotation of the uncoiling shaft.

7. The machine vision-based self-adhesive label defect detection device according to claim 6, characterized in that, The friction-blocking component includes an external mounting frame and a rotating friction head. The external mounting frame is fixedly connected to the uncoiling frame, and the rotating friction head is fixedly connected to the uncoiling shaft. An internally threaded cylinder is fixedly connected to the external mounting frame. A screw is internally threadedly connected to the internally threaded cylinder. A compression spring is fixedly connected to the screw. A friction pressure plate is rotatably connected to the compression spring. The friction pressure plate matches the rotating friction head. A rotation limit rod is fixedly connected to the friction pressure plate. A guide sleeve is slidably connected to the rotation limit rod. The guide sleeve is fixedly connected to the internally threaded cylinder.

8. The machine vision-based self-adhesive label defect detection device according to claim 7, characterized in that, Two rails are fixedly connected to the lifting table, and two rail grooves are opened at the bottom of the gantry frame. The two rails are slidably fitted in the two rail grooves respectively. A limit pin is detachably installed on the gantry frame, and multiple auxiliary insertion holes matching the limit pin are opened on one of the two rails.

9. The machine vision-based self-adhesive label defect detection device according to claim 8, characterized in that, The bottom of the auxiliary support is provided with a wheel groove, and a supporting rolling wheel is rotatably connected in the wheel groove. The central camera, which is installed on the same horizontal plane, is located between the two side light rangefinders.

10. A machine vision-based method for detecting defects in self-adhesive labels, characterized in that, The self-adhesive label defect detection device based on machine vision according to any one of claims 1-9 includes the following steps: S1. Before measurement, first equip the label take-up and drop-off assembly, electric lifting rod, grating ruler, pressure detection module, first servo motor, adjustment mechanism, central camera and two side light rangefinders with a control computer. Through the control computer, the operation control of the label take-up and drop-off assembly, electric lifting rod, first servo motor and adjustment mechanism can be realized. At the same time, the detection data of the grating ruler, pressure detection module, central camera and two side light rangefinders can be read, stored and displayed. The grating ruler is adjusted. When the label roll to be tested is not installed, the value of the grating ruler when the bottom end of the auxiliary support and the top surface of the lifting table form a support match is recorded, and this value is marked as the initial value of the grating ruler. S2. During measurement, first turn on the power to the control computer, label take-up and drop assembly, electric lifting rod, grating ruler, pressure detection module, first servo motor, adjustment mechanism, central camera and two side light rangefinders. Then, install the label roll to be tested into the label take-up and drop assembly. The label take-up and drop assembly enables the label roll to be tested to slide flat on the lifting table. As the label roll to be tested slides flat on the lifting table, the first servo motor is started to drive the rotation of the prism shaft. The circumferential linear velocity of the detection wheel on the prism shaft is controlled to be consistent with the speed of the label roll to be tested passing through the lifting table. The electric lifting rod is used to adjust the relative position of the lifting frame within the gantry, thereby achieving relative position control of the detection wheel relative to the label roll to be tested. S3. During the operation of the detection wheel, when the detection wheel is in a suspended state without contacting the label roll to be tested, the detection pressure reading of the pressure detection module is stable at a fixed reading. However, when the detection wheel comes into contact with the self-adhesive label and forms an interaction force, the reading of the pressure detection module will change. During the relative descent of the detection wheel, the grating ruler will form a real-time detection of the height change of the detection wheel. When the reading of the pressure detection module changes, the electric lifting rod will maintain the current working position and stop. Since the circumferential linear velocity of the detection wheel is the same as the speed of the label roll to be tested passing through the lifting table, the detection wheel will form a rolling operation relative to the label roll to be tested. The relative frictional displacement of the contact area between the two can be ignored. S4. The control computer records the final detection value of the grating ruler. At the same time, the central camera detects the relative distance between the label roll to be tested pressed down directly under the detection wheel and the central camera. The two side light rangefinders detect the relative distance between the label roll to be tested before and after being pressed down and the side light rangefinders, respectively. The control computer records the detection data of the side light rangefinders and the central camera, and combines the recorded data to form data analysis. S5. During data analysis, the final measured value of the grating ruler is subtracted from its initial value to obtain the relative distance between the bottom of the detection wheel and the lifting table. This distance represents the thickness of the label roll being tested when the detection wheel is pressed down. Subtracting the data of the label roll not yet pressed down by the detection wheel from the data detected by the central camera from the data detected by the edge light rangefinder gives the pressing distance of the detection wheel on the label roll. Adding this pressing distance to the thickness of the label roll after being pressed down by the detection wheel gives the natural thickness of the label roll when it is not pressed down by the detection wheel. By comparing the difference between the data of the label roll already pressed down by the detection wheel detected by the edge light rangefinder and the data detected by the central camera, the elastic recovery of the label roll can be evaluated. S6. When analyzing and processing the self-adhesive label image information acquired by the camera, the images of multiple self-adhesive labels acquired in the order of delivery are semi-transparent one by one. Then, the processed images are superimposed and overlapped. The composite image is visually compared and analyzed. If the overlap of the multiple label images is high and the overall outline of the self-adhesive labels in the superimposed image is neat and clear, it indicates that the corresponding multiple self-adhesive labels have no obvious defects. Otherwise, it indicates that there are problems with the corresponding self-adhesive labels in the superimposed images. Then, the multiple superimposed images are further screened to identify the corresponding defective self-adhesive labels.

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