Mesh cleanliness detection system and method for screen printing plate

Abstract

The invention discloses a screen printing plate mesh cleanliness detection system and method, and the system comprises a fixing device which is used for fixing a to-be-detected screen printing plate; the laser scanning device is arranged on one side of the fixing device, and the laser scanning device is used for generating a laser beam and scanning a pattern area of the silk-screen printing plate to be detected through the laser beam; the laser detection device is arranged on the other side of the fixing device and is opposite to the laser scanning device, and the laser detection device is used for receiving the laser penetrating through the meshes in the pattern area of the screen printing plate and generating a corresponding printing plate pattern grayscale image according to the amount of the laser penetrating through each mesh in the pattern area of the screen printing plate; and the cleanliness detection device is used for detecting the blockage condition of meshes of a pattern area of the screen printing plate according to the printing plate pattern gray level image and outputting a mesh cleanliness detection result. According to the invention, the efficiency of screen printing plate cleanliness detection and the accuracy of the detection result can be effectively improved.

Description

Technical Field

[0001] The present application relates to the field of screen printing technology, and in particular to a system and method for detecting the cleanliness of mesh holes of a screen printing plate. Background Art

[0002] Screen printing is a commonly used printing process, which uses the basic principle that the mesh holes of the screen printing plate are permeable to ink in the graphic part, while the mesh holes of the non-graphic part are not permeable to ink.

[0003] When printing, pour ink on one end of the screen printing plate, use a scraper to apply a certain pressure on the ink part of the screen printing plate, and move toward the other end of the screen printing plate. The ink is squeezed from the mesh of the image part to the substrate by the scraper during movement. Due to the viscosity of the ink, the imprint is fixed within a certain range. During the printing process, the scraper is always in line contact with the screen printing plate and the substrate, and the contact line moves with the movement of the scraper. Since a certain gap is maintained between the screen printing plate and the substrate, the screen printing plate generates a reaction force on the scraper through its own tension during printing, causing the ink and the screen to break and move, ensuring the printing size accuracy and avoiding dirtying the substrate. When the scraper is lifted after scraping the entire plate, the screen printing plate is also lifted, and the ink is gently scraped back to the initial position.

[0004] During the production process, screen printing plates are easily affected by many factors such as the environment, ink, water, and temperature. The mesh clogging problem of screen printing plates occurs frequently. Mesh clogging not only affects the printing quality, but also reduces printing efficiency, causing unnecessary economic losses to the company. Therefore, the used screen printing plates usually need to be cleaned before being used again. After cleaning, the screen printing plates need to be tested for cleanliness to avoid mesh clogging problems during use.

[0005] At present, there are two main methods for detecting the cleanliness of screen printing plates:

[0006] 1. Manual visual inspection: Visually determine whether the screen printing plate is blocked. This method relies on the operator's experience and attention, which may lead to inaccurate detection results. In addition, manual inspection is inefficient and cannot meet the needs of large-scale production.

[0007] 2. Finished product inspection: By inspecting the quality of the finished product after printing, it is indirectly determined whether the printing plate is blocked. This method belongs to post-testing and cannot find problems in time, resulting in an increase in the scrap rate.

[0008] Therefore, how to improve the efficiency of screen printing plate cleanliness detection and the accuracy of detection results is a problem that needs to be solved urgently in this field. Summary of the invention

[0009] To solve the above technical problems, the present application provides a system and method for detecting the mesh cleanliness of a screen printing plate, so as to improve the efficiency of detecting the cleanliness of the screen printing plate and the accuracy of the detection results.

[0010] The first object of the present application is to provide a system for detecting the mesh cleanliness of a screen printing plate.

[0011] The above object one of the present application is achieved by the following technical solutions:

[0012] A system for detecting the mesh cleanliness of a screen printing plate includes:

[0013] A fixing device for fixing the screen printing plate to be detected;

[0014] A laser scanning device is arranged on one side of the fixing device. The laser scanning device is used to generate a laser beam and scan the pattern area of the screen printing plate to be detected through the laser beam;

[0015] A laser detection device is arranged on the other side of the fixing device and is arranged opposite to the laser scanning device. The laser detection device is used to receive the laser transmitted through the mesh holes in the pattern area of the screen printing plate and generate a corresponding printed plate pattern grayscale image according to the amount of laser transmitted through each mesh hole in the pattern area of the screen printing plate;

[0016] A cleanliness detection device is used to detect the blockage condition of the mesh holes in the pattern area of the screen printing plate according to the printed plate pattern grayscale image and output a mesh cleanliness detection result.

[0017] Preferably, the laser scanning device includes a laser light source and a first XY moving platform. The laser light source is installed on the first XY moving platform. Among them,

[0018] The laser light source is used to emit a single beam of pulsed laser, and the diameter of the single beam of pulsed laser is greater than or equal to the diameter of the mesh holes of the screen printing plate;

[0019] The first XY moving platform is used to drive the laser light source to move so as to emit pulsed laser beams point by point to each mesh hole in the pattern area of the screen printing plate to be detected.

[0020] Preferably, the laser detection device includes a photoelectric sensor, a signal processing module and a second XY moving platform. The photoelectric sensor is installed on the second XY moving platform. Among them,

[0021] The photoelectric sensor is used to receive the single beam of pulsed laser emitted by the laser light source and convert the received laser beam into a corresponding voltage signal / current signal;

[0022] The signal processing module is configured to convert the voltage signal / current signal output by the photoelectric sensor into a corresponding gray value, thereby generating the gray image of the printing plate pattern;

[0023] The second XY moving platform is used to drive the photoelectric sensor to move synchronously with the laser light source, so that the photoelectric sensor and the laser light source are always aligned with each other.

[0024] Preferably, the photoelectric sensor is a photovoltaic cell or a photodiode.

[0025] Preferably, the mesh cleanliness detection system of the screen printing plate further includes a control module, and the signal input ends of the laser light source, the first XY moving platform and the second XY moving platform are respectively connected to the signal output end of the control module, wherein,

[0026] The control module is configured to control the first XY moving platform and the second XY moving platform to move synchronously and uniformly along a preset scanning path, and is further configured to control the laser light source to generate pulsed laser beams according to a preset pulse period during the movement of the first XY moving platform and the second XY moving platform, wherein,

[0027] The pulse period is determined according to the distance between two adjacent mesh holes in the same row or the same column within the pattern area of the screen printing plate to be detected and the moving speed of the first XY moving platform / second XY moving platform.

[0028] Preferably, the mesh cleanliness detection system of the screen printing plate further includes a data recording module, and the data recording module is configured to obtain the coordinate information of each mesh hole and the voltage signal / current signal corresponding to each mesh hole, and record the obtained coordinate information of each mesh hole and the voltage signal / current signal corresponding to each mesh hole in a preset table one by one, forming a voltage signal / current signal - coordinate value record table.

[0029] Preferably, when the signal processing module executes converting the voltage signal / current signal output by the photoelectric sensor into a corresponding gray value to generate the gray image of the printing plate pattern, it is specifically configured to:

[0030] Convert the voltage signal / current signal in the voltage signal / current signal - coordinate value record table into a corresponding gray value according to a preset conversion rule, obtaining a gray value - coordinate value record table;

[0031] Generate the gray image of the printing plate pattern according to the gray value - coordinate value record table.

[0032] Preferably, when the cleanliness detection device detects the clogging condition of the mesh holes in the pattern area of the screen printing plate according to the grayscale image of the printing plate pattern and outputs the mesh hole cleanliness detection result, it is specifically used for:

[0033] Segment the grayscale image of the printing plate pattern into multiple regional images, sequentially compare the grayscale values corresponding to each mesh hole on each regional image with a preset grayscale threshold, and mark the mesh holes with the difference between the grayscale value corresponding to the mesh hole on the regional image and the preset grayscale threshold greater than a preset difference, to obtain a mesh hole clogging marking map of the screen printing plate to be detected, and output the mesh hole clogging marking map as the mesh hole cleanliness detection result.

[0034] The second object of the present application is to provide a method for detecting the mesh hole cleanliness of a screen printing plate.

[0035] The above-mentioned second application object of the present application is achieved through the following technical solutions:

[0036] A method for detecting the mesh hole cleanliness of a screen printing plate, the method includes the following steps:

[0037] S1, build the mesh hole cleanliness detection system of the screen printing plate according to any one of the above-mentioned first application objects;

[0038] S2, install the screen printing plate to be detected on the fixing device;

[0039] S3, generate a laser beam through the laser scanning device and scan the pattern area of the screen printing plate to be detected through the laser beam;

[0040] S4, receive the laser transmitted through the mesh holes in the pattern area of the screen printing plate through the laser detection device, and generate a corresponding grayscale image of the printing plate pattern according to the amount of laser transmitted through each mesh hole in the pattern area of the screen printing plate;

[0041] S5, detect the clogging condition of the mesh holes in the pattern area of the screen printing plate according to the grayscale image of the printing plate pattern through the cleanliness detection device, and output the mesh hole cleanliness detection result.

[0042] Preferably, between steps S2 and S3, the method further includes the following steps:

[0043] S21, determine the initial detection mesh holes on the pattern area of the screen printing plate to be detected according to a preset initial detection position determination strategy, so that each pulsed laser beam emitted by the laser scanning device can irradiate the corresponding mesh holes on the screen printing plate to be detected during subsequent laser scanning;

[0044] S22. Perform path planning based on the determined initial detection mesh and the pattern of the pattern area of the screen printing plate to be detected, and obtain a scanning path for scanning the pattern area of the screen printing plate to be detected.

[0045] The above technical solution of this application has the following advantages compared with the prior art:

[0046] In this application, the screen printing plate to be detected is fixed by a fixing device. A laser scanning device disposed on one side of the fixing device generates a laser beam and scans the pattern area of the screen printing plate to be detected through the laser beam. A laser detection device disposed on the other side of the fixing device and opposite to the laser scanning device receives the laser transmitted through the mesh holes in the pattern area of the screen printing plate, and generates a corresponding printed plate pattern grayscale image according to the amount of laser transmitted through each mesh hole in the pattern area of the screen printing plate. The cleanliness detection device detects the blockage condition of the mesh holes in the pattern area of the screen printing plate according to the printed plate pattern grayscale image and outputs a mesh hole cleanliness detection result, thereby realizing the automatic detection of the mesh hole cleanliness of the screen printing plate, effectively improving the efficiency of the screen printing plate cleanliness detection and the accuracy of the detection result. Description of the Drawings

[0047] In order to more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in this application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0048] Figure 1 It is a schematic structural diagram of a mesh hole cleanliness detection system for a screen printing plate in an embodiment of this application;

[0049] Figure 2 It is a schematic block diagram of the principle of a mesh hole cleanliness detection system for a screen printing plate in an embodiment of this application;

[0050] Figure 3 It is a schematic diagram of one area image of the printed plate pattern grayscale image in an embodiment of this application;

[0051] Figure 4 It is a schematic flowchart of a method for detecting the mesh hole cleanliness of a screen printing plate in an embodiment of this application. Detailed Embodiments

[0052] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of this application.

[0053] In the embodiments provided by this application, it should be understood that the disclosed methods and systems can be implemented in other ways. The system embodiments described below are only illustrative. For example, the division of units and modules is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or modules can be combined, or can be integrated into another system, or some features can be ignored, or not executed. In addition, the couplings, direct couplings, or communication connections between the various components shown or discussed can be through some interfaces, indirect couplings or communication connections of devices or modules, and can be electrical, mechanical or other forms.

[0054] In addition, in each embodiment of this application, each functional unit can be all integrated in a processor, or each unit can be separately used as a device, or two or more units can be integrated in a device; each functional unit in each embodiment of this application can be implemented in the form of hardware, or can be implemented in the form of a combination of hardware and software functional units.

[0055] Those of ordinary skill in the art can understand that all or part of the steps of implementing the following method embodiments can be completed through program instructions and related hardware. The foregoing program instructions can be stored in a computer-readable storage medium. When the program instructions are executed, the steps of the following method embodiments are executed; and the foregoing storage medium includes: various media such as removable storage devices, read-only memory (ROM), magnetic disks or optical discs that can store program codes.

[0056] In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of this application, the meanings of "a plurality of" and "several" are two or more, unless otherwise specifically defined.

[0057] As Figure 1 、 Figure 2 shown, the embodiments of this application provide a mesh cleanliness detection system for a screen printing plate, a fixing device, which is used to fix the screen printing plate to be detected;

[0058] A laser scanning device is arranged on one side of a fixing device. The laser scanning device is used to generate a laser beam and scan a pattern area of a silk screen printing plate to be detected through the laser beam;

[0059] A laser detection device is arranged on the other side of the fixing device and is arranged opposite to the laser scanning device. The laser detection device is used to receive the laser transmitted through the mesh holes in the pattern area of the silk screen printing plate, and generate a corresponding printing plate pattern grayscale image according to the amount of laser transmitted through each mesh hole in the pattern area of the silk screen printing plate;

[0060] A cleanliness detection device is used to detect the blockage condition of the mesh holes in the pattern area of the silk screen printing plate according to the printing plate pattern grayscale image, and output a mesh hole cleanliness detection result.

[0061] In this embodiment, the working principle of the mesh hole cleanliness detection system of the silk screen printing plate is as follows:

[0062] When it is necessary to detect the mesh hole cleanliness of the silk screen printing plate, first install the silk screen printing plate to be detected on the fixing structure to ensure stability during the whole detection process. Then, use the laser scanning device to generate a laser beam and scan the pattern area of the silk screen printing plate to be detected through the laser beam. Next, use the laser detection device to receive the laser transmitted through the mesh holes in the pattern area of the silk screen printing plate, and generate a corresponding printing plate pattern grayscale image according to the amount of laser transmitted through each mesh hole in the pattern area of the silk screen printing plate. Finally, use the cleanliness detection device to detect the blockage condition of the mesh holes in the pattern area of the silk screen printing plate according to the printing plate pattern grayscale image, and output a mesh hole cleanliness detection result.

[0063] In the embodiment of the present application, the silk screen printing plate to be detected is fixed by the fixing device. The laser scanning device arranged on one side of the fixing device generates a laser beam and scans the pattern area of the silk screen printing plate to be detected through the laser beam. The laser detection device arranged on the other side of the fixing device and opposite to the laser scanning device receives the laser transmitted through the mesh holes in the pattern area of the silk screen printing plate, and generates a corresponding printing plate pattern grayscale image according to the amount of laser transmitted through each mesh hole in the pattern area of the silk screen printing plate. The cleanliness detection device detects the blockage condition of the mesh holes in the pattern area of the silk screen printing plate according to the printing plate pattern grayscale image, and outputs a mesh hole cleanliness detection result, so as to realize the automatic detection of the mesh hole cleanliness of the silk screen printing plate, effectively improve the efficiency of the silk screen printing plate cleanliness detection and the accuracy of the detection result.

[0064] In one embodiment, the laser scanning device includes a laser light source and a first XY moving platform. The laser light source is installed on the first XY moving platform. Among them,

[0065] The laser light source is used to emit a single-beam pulsed laser, wherein the diameter of the single-beam pulsed laser is greater than or equal to the diameter of the mesh holes of the screen printing plate;

[0066] The first XY moving platform is used to drive the laser light source to move, so as to emit pulsed laser beams point by point into each mesh hole within the pattern area of the screen printing plate to be detected.

[0067] In this embodiment, the laser scanning device is provided with a laser light source and a first XY moving platform, and the laser light source is installed on the first XY moving platform. During the process of the laser light source emitting a single-beam pulsed laser, the first XY moving platform is used to drive the laser light source to move, and pulsed laser beams are emitted point by point into each mesh hole within the pattern area of the screen printing plate to be detected, thereby realizing the laser scanning of each mesh hole within the pattern area of the screen printing plate.

[0068] In this embodiment, in order to ensure that the light transmission amount of mesh holes with different degrees of blockage can be accurately measured, it is necessary to ensure that the diameter of the laser beam is not less than the diameter of the mesh holes of the screen printing plate. Preferably, the diameter of the laser beam is slightly larger than the diameter of the mesh holes of the screen printing plate (but less than the sum of the mesh hole and the mesh wires on both sides of the mesh hole). In this way, it can be ensured that the light transmission amounts of mesh holes with different degrees of blockage are different, and when detecting a certain mesh hole, it can be ensured that the light outside the laser beam does not pass through other mesh holes around the mesh hole and enter the other side of the screen printing plate to interfere with the actual illuminance of the mesh hole and affect the accuracy of the detection result of the light transmission amount of the mesh hole.

[0069] In one embodiment, the laser detection device includes a photoelectric sensor, a signal processing module, and a second XY moving platform. The photoelectric sensor is installed on the second XY moving platform, wherein,

[0070] The photoelectric sensor is used to receive the single-beam pulsed laser emitted by the laser light source and convert the received laser beam into a corresponding voltage signal / current signal;

[0071] The signal processing module is used to convert the voltage signal / current signal output by the photoelectric sensor into a corresponding gray value to generate a gray image of the printing plate pattern;

[0072] The second XY moving platform is used to drive the photoelectric sensor to move synchronously with the laser light source, so that the photoelectric sensor and the laser light source are always aligned with each other.

[0073] In this embodiment, the laser detection device is configured by setting an optoelectronic sensor, a signal processing module, and a second XY moving platform. The optoelectronic sensor is installed on the second XY moving platform. The optoelectronic sensor receives a single-beam pulsed laser emitted by the laser light source and converts the received laser beam into a corresponding voltage signal / current signal. The signal processing module converts the voltage signal / current signal output by the optoelectronic sensor into a corresponding grayscale value to generate a grayscale image of the printing plate pattern. During the process that the optoelectronic sensor receives the single-beam pulsed laser emitted by the laser light source, the second XY moving platform is used to drive the optoelectronic sensor to move synchronously with the laser light source, so that the optoelectronic sensor and the laser light source are always aligned with each other, thereby ensuring that the laser emitted by the laser emission device can be received.

[0074] It should be noted that the first XY moving platform and the second XY moving platform adopt existing XY moving platforms, and their specific structures and working principles belong to the prior art and will not be elaborated here.

[0075] In one embodiment, the optoelectronic sensor is a photovoltaic cell or a photodiode. A photovoltaic cell is a semiconductor component that generates an electromotive force under light irradiation. For example, a silicon photovoltaic cell. Its principle is that the PN junction of the semiconductor in the photovoltaic cell generates new electron-hole pairs under the action of light. The electrons and holes move to both sides of the PN junction under the action of the PN junction electric field to form an additional potential difference, thereby outputting a voltage. The photovoltaic cell can receive the laser passing through the mesh holes and convert the optical signal into a voltage signal. The more laser the photovoltaic cell receives, the higher the voltage output by the photovoltaic cell. A photodiode, like an ordinary diode, is also a semiconductor device composed of a PN junction and also has the characteristic of unidirectional conductivity. However, in the circuit, it does not act as a rectifying element but is an optoelectronic sensor device that converts an optical signal into an electrical signal. The photodiode operates under reverse voltage. When there is no light irradiation, the reverse current is extremely weak, called dark current. When there is light irradiation, the reverse current rapidly increases to dozens of microamperes, called photocurrent. The greater the intensity of the light, the greater the reverse current. The change in light causes a change in the current of the photodiode, which can convert the optical signal into an electrical signal. The photodiode can receive the laser passing through the mesh holes and convert the optical signal into a current signal. The more laser the photodiode receives, the greater the current output by the photodiode.

[0076] Specifically, in this embodiment, the optoelectronic sensor uses a silicon photovoltaic cell with the model number SGPN96CR (chip size 3.5mm * 5.5mm, detection range 360nm - 1100nm), or a silicon photovoltaic cell with the model number SGPN1095CR (chip size 6mm * 6mm, detection range 360nm - 1100nm).

[0077] For a mesh hole, the higher the transmittance of the laser, the smaller the degree of mesh hole blockage, that is, the better the cleanliness of the mesh hole. Therefore, in this application, the cleanliness of the mesh hole is detected by detecting the light transmittance of the mesh hole.

[0078] In one embodiment, the mesh hole cleanliness detection system of the screen printing plate further includes a control module. The signal input ends of the laser light source, the first XY moving platform, and the second XY moving platform are respectively connected to the signal output end of the control module. Among them,

[0079] The control module is used to control the first XY moving platform and the second XY moving platform to move synchronously and uniformly according to a preset scanning path, and is also used to control the laser light source to generate pulsed laser beams according to a preset pulse period during the movement of the first XY moving platform and the second XY moving platform. Among them,

[0080] The pulse period is determined according to the distance between two adjacent mesh holes in the same row or the same column within the pattern area of the screen printing plate to be detected and the moving speed of the first XY moving platform / the second XY moving platform.

[0081] In this embodiment, by setting the control module, and connecting the signal input ends of the laser light source, the first XY moving platform, and the second XY moving platform to the signal output end of the control module respectively, and enabling the control module to control the first XY moving platform and the second XY moving platform to move synchronously and uniformly according to a preset scanning path, and can also control the laser light source to generate pulsed laser beams according to a preset pulse period during the movement of the first XY moving platform and the second XY moving platform. In this way, through the control module, the laser light source, the first XY moving platform, and the second XY moving platform can work synchronously.

[0082] Specifically, the pulse period of the pulsed laser beam generated by the laser light source is determined according to the distance between two adjacent mesh holes in the same row or the same column within the pattern area of the screen printing plate to be detected and the moving speed of the first XY moving platform / the second XY moving platform. In this implementation, the pulse period is the distance between two adjacent mesh holes in the same row or the same column within the pattern area of the screen printing plate to be detected divided by the moving speed of the first XY moving platform / the second XY moving platform, that is, the laser light source emits a pulsed laser beam every time it moves a grid distance, so as to realize point-by-point detection of all mesh holes within the pattern area of the screen printing plate to be detected.

[0083] In one embodiment, the mesh cleanliness detection system of the screen printing plate further includes a data recording module. The data recording module is used to obtain the coordinate information of each mesh and the voltage signal / current signal corresponding to each mesh, and record the obtained coordinate information of each mesh and the voltage signal / current signal corresponding to each mesh in a preset table one by one, forming a voltage signal / current signal - coordinate value record table.

[0084] In this embodiment, by setting the data recording module to obtain the coordinate information of each mesh and the voltage signal / current signal corresponding to each mesh, and recording the obtained coordinate information of each mesh and the voltage signal / current signal corresponding to each mesh in a preset table one by one, a voltage signal / current signal - coordinate value record table is formed, so as to be used for generating the grayscale image of the printing plate pattern subsequently.

[0085] Specifically, in this embodiment, the data recording module can obtain the coordinate information of each mesh from the control module that controls the first XY moving platform and the second XY moving platform, and obtain the voltage signal / current signal corresponding to each mesh from the photoelectric sensor.

[0086] In one embodiment, when the signal processing module executes the conversion of the voltage signal / current signal output by the photoelectric sensor into the corresponding grayscale value to generate the grayscale image of the printing plate pattern, it is specifically used for:

[0087] Converting the voltage signal / current signal in the voltage signal / current signal - coordinate value record table into the corresponding grayscale value according to a preset conversion rule, to obtain a grayscale value - coordinate value record table;

[0088] Generating the grayscale image of the printing plate pattern according to the grayscale value - coordinate value record table.

[0089] Specifically, in order to quickly convert the voltage signal / current signal in the voltage signal / current signal - coordinate value record table into the corresponding grayscale value, the functional relationship between the voltage value / current value and the grayscale value can be pre - constructed to form a data conversion model (that is, form the preset conversion rule). When performing the grayscale value conversion, input the value of the voltage signal / current signal into the pre - constructed data conversion model, and the grayscale value corresponding to the value of the voltage signal / current signal can be obtained. The larger the value of the voltage signal / current signal, the larger the corresponding grayscale value. In this way, the blockage situation of each mesh in the pattern area of the screen printing plate to be detected can be intuitively seen through the grayscale image of the printing plate pattern.

[0090] In one embodiment, when the cleanliness detection device executes the detection of the blockage situation of the meshes in the pattern area of the screen printing plate according to the grayscale image of the printing plate pattern and outputs the mesh cleanliness detection result, it is specifically used for:

[0091] The grayscale image of the printed pattern is segmented into multiple regional images, and the grayscale values corresponding to each mesh hole on each regional image are sequentially compared with a preset grayscale threshold. The mesh holes with the difference between the grayscale value corresponding to the mesh hole on the regional image and the preset grayscale threshold greater than the preset difference are marked, obtaining a mesh hole blockage marking map of the screen printing plate to be detected. The mesh hole blockage marking map is output as the mesh hole cleanliness detection result.

[0092] In this embodiment, the cleanliness detection device segments the grayscale image of the printed pattern into multiple regional images, and sequentially compares the grayscale values corresponding to each mesh hole on each regional image with a preset grayscale threshold. According to the comparison results, markings are made to obtain a mesh hole blockage marking map of the screen printing plate to be detected, and then the mesh hole blockage marking map is output as the mesh hole cleanliness detection result, enabling the user to better further target the cleaning of the mesh hole blockage area of the screen printing plate according to the marking situation of the mesh hole blockage marking map in the output mesh hole cleanliness detection result.

[0093] Specifically, the preset grayscale threshold is the average value of the grayscale values obtained by detecting the mesh holes on the screen printing plate without blockage through a laser scanning device and a laser detection device. Due to the accuracy problem of the laser detection device itself, there may be errors when the laser detection device converts the optical signal into an electrical signal, and there will also be interference from ambient light during the detection process. Moreover, slight blockage of the mesh holes does not affect the printing quality. Therefore, in this embodiment, based on the above reasons, a preset difference is set according to experimental data to reduce the detection error, thereby improving the accuracy of the detection result. That is, when the difference between the grayscale value corresponding to the mesh hole on the regional image and the preset grayscale threshold is greater than the preset difference, it indicates that the blockage situation of the mesh hole exceeds the allowable blockage degree for normal printing. At this time, the mesh hole is marked to facilitate quickly finding the blocked mesh hole during subsequent cleaning, so as to target the cleaning of the blocked mesh hole and improve the cleaning efficiency and quality of the subsequent screen printing plate.

[0094] To better understand the solution of this application, the following is illustrated with specific examples:

[0095] Embodiment 1

[0096] 1. Fix the screen printing plate (the mesh size of the image area is 300 mesh) to be detected after cleaning on the fixing device to ensure that the screen plate remains stable throughout the test process;

[0097] 2. Adjust the diameter of the laser beam emitted by the laser scanning device to be slightly larger than the aperture diameter of the screen printing plate. The laser beam emitted by the laser scanning device scans the pattern area on the screen printing plate point by point. The laser detection device receives the laser passing through the apertures in the pattern area of the screen printing plate (the laser receiving device of the laser detection device uses an SGPN96CR silicon photocell) to ensure that the light intensity change of each aperture can be accurately recorded;

[0098] 3. For each aperture, record the XY coordinates and the corresponding voltage values to form a voltage signal - coordinate value record table.

[0099] The following table is the voltage signal - coordinate value record table of each aperture in a certain area of the pattern area of the screen printing plate. The larger the voltage value, the higher the light transmittance and the better the cleanliness.

[0100] Mesh number X coordinate (μm) Y coordinate (μm) Voltage value (mV) 1 50 50 355 2 100 50 502 3 150 50 489 4 200 50 503 5 250 50 123 ... ... ... ... 961 1550 1550 488

[0101] 4. Based on the voltage values in the above Excel table, the laser detection device automatically generates a corresponding grayscale image. This grayscale image is as Figure 3 shown. The voltage value of each aperture corresponds to a different grayscale level. The area with a lower voltage value is displayed as a dark area, indicating a more serious blockage of the aperture; the area with a higher voltage value is displayed as a bright area, indicating that this area is cleaner.

[0102] As Figure 4 shown, the embodiment of the present application provides a method for detecting the cleanliness of the apertures of a screen printing plate. This method may include the following steps:

[0103] S1. Set up the system for detecting the cleanliness of the apertures of the screen printing plate in any of the above - mentioned embodiments;

[0104] S2. Install the screen printing plate to be detected on the fixing device;

[0105] S3. Generate a laser beam through the laser scanning device and scan the pattern area of the screen printing plate to be detected with the laser beam;

[0106] S4. Receive the laser passing through the apertures in the pattern area of the screen printing plate through the laser detection device, and generate a corresponding grayscale image of the printing plate pattern according to the amount of laser passing through each aperture in the pattern area of the screen printing plate;

[0107] S5. Detect the blockage condition of the apertures in the pattern area of the screen printing plate according to the grayscale image of the printing plate pattern through the cleanliness detection device, and output the detection result of the aperture cleanliness.

[0108] It should be noted that the working principle of the method for detecting the mesh cleanliness of the screen printing plate in this embodiment is the same as that of the system for detecting the mesh cleanliness of the screen printing plate in the above embodiment, and will not be elaborated here.

[0109] Since the method for detecting the mesh cleanliness of the screen printing plate in this embodiment is implemented by using the system for detecting the mesh cleanliness of the screen printing plate in the above embodiment, therefore, the beneficial effects of the method for detecting the mesh cleanliness of the screen printing plate in this embodiment are the same as those of the system for detecting the mesh cleanliness of the screen printing plate in the above embodiment.

[0110] In one embodiment, between steps S2 and S3, the method for detecting the mesh cleanliness of the screen printing plate further includes the following steps:

[0111] S21, determine the initial detection mesh holes on the pattern area of the screen printing plate to be detected by the laser scanning device according to a preset initial detection position determination strategy, so that each pulsed laser beam emitted by the laser scanning device during subsequent laser scanning can irradiate the corresponding mesh holes of the screen printing plate to be detected;

[0112] S22, perform path planning according to the determined initial detection mesh holes and the pattern of the pattern area of the screen printing plate to be detected, and obtain the scanning path for scanning the pattern area of the screen printing plate to be detected.

[0113] Since there may be installation deviations when the screen printing plate is installed on the fixing device, and the mesh hole diameter of the screen printing plate is very small, generally at the micron level. For example, the mesh hole diameter of a 300-mesh screen printing plate is 50 μm. Therefore, if there are slight deviations in the position of the screen printing plate after installation (such as lateral deviation, longitudinal deviation, or overall tilt), it is possible that some of the pulsed laser beams emitted when the laser scanning device starts scanning according to the preset initial position and initial scanning path will irradiate the mesh wires between two meshes, and the laser amount received by the laser detection device is not the actual light transmission amount of the mesh holes, resulting in inaccurate detection results of the mesh cleanliness of the screen printing plate finally.

[0114] In this embodiment, after the screen printing plate to be detected is installed on the fixing device, first, according to the preset initial detection position determination strategy, the initial detection mesh holes on the pattern area of the screen printing plate to be detected are determined by the laser scanning device, and then the scanning path is obtained through path planning according to the determined initial detection mesh holes and the pattern of the pattern area of the screen printing plate to be detected. Thus, when the laser scanning device generates a laser beam and scans the pattern area of the screen printing plate to be detected through the laser beam, the first pulsed laser beam is emitted starting from the determined initial detection mesh hole, and the scanning is performed according to the preset scanning path. In this way, even if the position of the screen printing plate deviates during installation, each pulsed laser can be aligned with the corresponding mesh hole, thereby ensuring the accuracy of the final mesh hole cleanliness detection result.

[0115] Specifically, in one embodiment, the specific process of determining the initial detection mesh holes in step S21 is as follows:

[0116] S211, the pattern area of the screen printing plate is scanned by the laser scanning device according to the preset initial position and initial scanning path, and the laser scanning device emits a pulsed laser beam every time it moves a grid distance;

[0117] S212, the laser detection device receives the laser transmitted through the mesh holes in the pattern area of the screen printing plate, and generates a corresponding initial grayscale image of the printing plate pattern according to the laser amount transmitted through each mesh hole in the pattern area of the screen printing plate;

[0118] S213, select a mesh hole with a grayscale value not less than the preset grayscale threshold in the initial grayscale image of the printing plate pattern as the initial detection mesh hole.

[0119] It can be understood that when the grayscale value of the mesh hole is not less than the preset grayscale threshold, it indicates that the mesh hole is not blocked.

[0120] Specifically, in one embodiment, the specific process of path planning in step S22 is as follows:

[0121] S221, starting from the position where the initial detection mesh hole is used as the position where the first pulsed laser beam is emitted during the scanning process of the laser scanning device, scan the pattern area of the screen printing plate to be detected;

[0122] S222, during the scanning process, the moving paths of the first XY moving platform and the second moving platform are synchronously adjusted multiple times, and corresponding grayscale images of multiple printing plate patterns are obtained, and the coordinates of the position where the laser scanning device emits each pulsed laser beam in the adjusted moving path each time are recorded;

[0123] S223. When there are N consecutive mesh holes in the same row or the same column of the mesh holes in the obtained grayscale image of the printed pattern, and the grayscale values corresponding to these mesh holes are not less than a preset grayscale threshold (indicating that each pulsed laser beam emitted by the laser scanning device in this scanning path is aligned with the corresponding mesh hole on the screen printing plate), path planning is performed based on the coordinates of each of these N consecutive mesh holes and the pattern of the pattern area of the screen printing plate to be detected, and a scanning path for scanning the pattern area of the screen printing plate to be detected is obtained.

[0124] Specifically, N is a positive integer, and N≥2. The larger N is, the more accurate the obtained scanning path will be. In practical applications, the value of N is related to the diameter of the laser beam and the size of the mesh hole, and generally takes a value of 3 to 5.

[0125] In this specification, each embodiment is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. For the same or similar parts among the embodiments, reference can be made to each other. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple. For the relevant parts, reference can be made to the description in the method part.

[0126] Those skilled in the art can further realize that the units and algorithm steps of each example described in combination with the embodiments disclosed in this embodiment can be implemented by electronic hardware, computer software, or a combination of the two. To clearly illustrate the interchangeability of hardware and software, the components and steps of each example have been generally described according to their functions in the above description. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of this application.

[0127] The steps of the method or algorithm described in combination with the embodiments disclosed in this embodiment can be directly implemented by hardware, a software module executed by a processor, or a combination of the two. The software module can be placed in a random access memory (RAM), internal memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, register, hard disk, removable disk, CD-ROM, or any other form of storage medium well-known in the technical field.

[0128] The foregoing description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A screen printing plate mesh cleanliness detection system, characterized in that: include: A fixing device, which is used to fix the screen printing plate to be tested; A laser scanning device, which is arranged on one side of the fixing device, and is used to generate a laser beam and scan the pattern area of ​​the screen printing plate to be detected by the laser beam; a laser detection device, which is arranged on the other side of the fixing device and is arranged opposite to the laser scanning device, and is used to receive the laser transmitted through the meshes in the pattern area of ​​the screen printing plate, and generate a corresponding grayscale image of the printing plate pattern according to the amount of laser transmitted through each mesh in the pattern area of ​​the screen printing plate; The cleanliness detection device is used to detect the blockage of the mesh in the pattern area of ​​the screen printing plate according to the grayscale image of the printing plate pattern, and output the mesh cleanliness detection result.

2. The screen printing plate mesh cleanliness detection system according to claim 1, characterized in that: The laser scanning device comprises a laser light source and a first XY moving platform, wherein the laser light source is mounted on the first XY moving platform, The laser light source is used to emit a single beam of pulsed laser, wherein the diameter of the single beam of pulsed laser is greater than or equal to the diameter of the mesh of the screen printing plate; The first XY moving platform is used to drive the laser light source to move so as to emit a pulsed laser beam point by point to each mesh hole in the pattern area of ​​the screen printing plate to be inspected.

3. The screen printing plate mesh cleanliness detection system according to claim 2, characterized in that: The laser detection device includes a photoelectric sensor, a signal processing module and a second XY moving platform, wherein the photoelectric sensor is mounted on the second XY moving platform, The photoelectric sensor is used to receive the single beam of pulsed laser emitted by the laser light source and convert the received laser beam into a corresponding voltage signal / current signal; The signal processing module is used to convert the voltage signal / current signal output by the photoelectric sensor into a corresponding grayscale value to generate a grayscale image of the printed plate pattern; The second XY moving platform is used to drive the photoelectric sensor to move synchronously with the laser light source, so that the photoelectric sensor and the laser light source are always aligned with each other.

4. The screen printing plate mesh cleanliness detection system according to claim 3, characterized in that: The photoelectric sensor is a photocell or a photodiode.

5. The screen printing plate mesh cleanliness detection system according to claim 3, characterized in that: It also includes a control module, and the signal input ends of the laser light source, the first XY moving platform and the second XY moving platform are respectively connected to the signal output end of the control module, wherein: The control module is used to control the first XY moving platform and the second XY moving platform to move synchronously and at a uniform speed according to a preset scanning path, and is also used to control the laser light source to generate a pulse laser beam according to a preset pulse period during the movement of the first XY moving platform and the second XY moving platform, wherein: The pulse period is determined according to the distance between two adjacent mesh holes in the same row or column in the pattern area of ​​the screen printing plate to be detected and the moving speed of the first XY moving platform / the second XY moving platform.

6. The screen printing plate mesh cleanliness detection system according to claim 5, characterized in that: It also includes a data recording module, which is used to obtain the coordinate information of each mesh and the voltage signal / current signal corresponding to each mesh, and record the acquired coordinate information of each mesh and the voltage signal / current signal corresponding to each mesh in a preset table one by one to form a voltage signal / current signal-coordinate value recording table.

7. The screen printing plate mesh cleanliness detection system according to claim 6, characterized in that: The signal processing module is specifically used to convert the voltage signal / current signal output by the photoelectric sensor into a corresponding grayscale value to generate the grayscale image of the printed plate pattern: Converting the voltage signal / current signal in the voltage signal / current signal-coordinate value recording table into corresponding grayscale values ​​according to a preset conversion rule to obtain a grayscale value-coordinate value recording table; The printing plate pattern grayscale image is generated according to the grayscale value-coordinate value record table.

8. The screen printing plate mesh cleanliness detection system according to any one of claims 1 to 7, characterized in that: The cleanliness detection device detects the blockage of the mesh in the pattern area of ​​the screen printing plate according to the grayscale image of the printing plate pattern and outputs the mesh cleanliness detection result, which is specifically used for: The grayscale image of the printed plate pattern is divided into multiple regional images, and the grayscale value corresponding to each mesh on each of the regional images is compared with a preset grayscale threshold in turn, and the meshes whose difference between the grayscale value corresponding to the mesh on the regional image and the preset grayscale threshold is greater than the preset difference are marked to obtain a mesh blockage marking map of the screen printing plate to be detected, and the mesh blockage marking map is output as the mesh cleanliness detection result.

9. A method for detecting the cleanliness of mesh of a screen printing plate, characterized in that: The method comprises the following steps: S1, constructing a mesh cleanliness detection system for a screen printing plate according to any one of claims 1 to 8; S2, mounting the screen printing plate to be tested on the fixing device; S3, generating a laser beam by the laser scanning device and scanning the pattern area of ​​the screen printing plate to be detected by the laser beam; S4, receiving the laser light transmitted through the mesh holes in the pattern area of ​​the screen printing plate through the laser detection device, and generating a corresponding grayscale image of the printing plate pattern according to the amount of laser light transmitted through each mesh hole in the pattern area of ​​the screen printing plate; S5, using the cleanliness detection device to detect the blockage of the mesh in the pattern area of ​​the screen printing plate according to the grayscale image of the printing plate pattern, and output the mesh cleanliness detection result.

10. The method for detecting mesh cleanliness of a screen printing plate according to claim 9, characterized in that: Between steps S2 and S3, the method further comprises the following steps: S21, determining the initial detection mesh on the pattern area of ​​the screen printing plate to be detected by the laser scanning device according to a preset initial detection position determination strategy, so that each pulse laser beam emitted by the laser scanning device in the subsequent laser scanning process can irradiate the corresponding mesh of the screen printing plate to be detected; S22, performing path planning according to the determined initial detection mesh and the pattern of the pattern area of ​​the screen printing plate to be detected, to obtain a scanning path for scanning the pattern area of ​​the screen printing plate to be detected.

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