Liquid level detection device, mask cleaning machine and cleaning method of liquid level detection device

Abstract

This application provides a liquid level detection device, a mask cleaning machine, and a cleaning method for the liquid level detection device. The liquid level detection device includes a liquid level tube, an air supply source, a liquid supply source, a three-way solenoid valve, a connecting pipe, an air supply pipe, and a pressure sensor. The liquid level tube includes an upper opening and a lower opening. The air supply source provides detection gas. The liquid supply source provides flushing liquid. The three-way solenoid valve includes a first inlet, a second inlet, and an outlet. The first inlet is connected to the liquid supply source. The outlet of the three-way solenoid valve is connected to the upper opening. The air supply pipe connects the second inlet and the air supply source. The pressure sensor is installed on the air supply pipe to detect the internal pressure of the air supply pipe. This allows for timely removal of crystals on the inner surface of the flushing liquid level tube, preventing the pressure sensor from inaccurately reflecting the liquid level in the liquid level tube based on the internal pressure of the air supply pipe.

Description

Technical Field

[0001] This application relates to the field of mask cleaning equipment technology, and in particular to a liquid level detection device, a mask cleaning machine, and a cleaning method for the liquid level detection device. Background Technology

[0002] In thin film fabrication processes such as semiconductor manufacturing and flat panel displays, vapor deposition is a technique that involves heating and evaporating materials to deposit them onto a substrate to form a thin film. A vapor deposition mask is a template used in the vapor deposition process. Masks can be recycled, but they need to be cleaned after each vapor deposition process. A cleaning machine for cleaning vapor deposition masks includes a cleaning tank and a level detector. The cleaning tank holds cleaning fluid, and the level detector detects the fluid level in the tank, allowing for timely replenishment to ensure a smooth cleaning process.

[0003] In existing technology, liquid level detectors include nitrogen level tubes. The principle of a nitrogen level tube is that both the upper and lower ends of the tube are open; the lower opening extends into the cleaning tank, and the upper opening is the nitrogen inlet. Thus, cleaning fluid enters the nitrogen level tube from the lower opening, and nitrogen enters from the upper opening. The nitrogen generates feedback pressure, which allows the liquid level in the nitrogen level tube to be determined, thereby indicating the liquid level in the cleaning tank.

[0004] However, crystals easily adhere to the inner wall of the nitrogen level pipe, which reduces the accuracy of the nitrogen feedback pressure, thus causing abnormal level feedback in the cleaning tank. Summary of the Invention

[0005] To address the aforementioned problems, embodiments of this application provide a liquid level detection device, a mask cleaning machine, and a cleaning method for the liquid level detection device, thereby at least partially solving the problems described above.

[0006] In a first aspect, this application provides a liquid level detection device, the liquid level detection device comprising:

[0007] A liquid level tube, the liquid level tube including an upper opening and a lower opening, the upper opening and the lower opening being located at opposite ends of the liquid level tube;

[0008] Gas supply source, used to provide detection gas;

[0009] Liquid supply source, used to provide flushing liquid;

[0010] The three-way solenoid valve includes a first inlet, a second inlet, and an outlet. The first inlet is connected to the liquid supply source, and the outlet of the three-way solenoid valve is connected to the upper opening.

[0011] A gas supply pipe is connected between the second inlet of the three-way solenoid valve and the gas supply source. By switching the three-way solenoid valve, the detection gas can enter the liquid level tube from the upper opening, or the flushing liquid can enter the liquid level tube from the upper opening to flush the inner surface of the liquid level tube.

[0012] A pressure sensor, installed on the gas supply pipe, is used to detect the internal pressure of the gas supply pipe when the detection gas enters the liquid level pipe from the upper opening.

[0013] In one alternative embodiment, the material of the level tube includes polyetheretherketone (PEEK).

[0014] In one alternative embodiment, the lower opening extends through the lower end face of the level tube.

[0015] In one optional embodiment, the liquid level detection device further includes a liquid supply pipe and a first check valve, the liquid supply pipe being connected between the first inlet of the three-way solenoid valve and the liquid supply source, and the first check valve being installed on the liquid supply pipe.

[0016] In one optional embodiment, the liquid level detection device further includes a second check valve, which is installed on the air supply pipe and located between the pressure sensor and the air supply source.

[0017] Secondly, this application provides a mask cleaning machine, which includes a cleaning tank, a controller, and the aforementioned liquid level detection device. The controller and the liquid level detection device are electrically connected to a three-way solenoid valve. The lower opening of the liquid level tube of the liquid level detection device is inserted into the cleaning tank to detect the liquid level.

[0018] In one alternative embodiment, the cleaning machine further includes a clamping member mounted on the cleaning tank for clamping the liquid level tube.

[0019] In one optional embodiment, the cleaning machine further includes a drain valve installed at the outlet of the cleaning tank, and the controller is electrically connected to the drain valve for controlling the drain valve to open or close.

[0020] In one optional embodiment, the cleaning machine further includes a digital display device and an alarm device. The controller, pressure sensor, digital display device, and alarm device are all electrically connected. The controller calculates the current liquid level based on the pressure feedback from the pressure sensor and displays the current liquid level on the digital display device. When the current liquid level is lower than a preset threshold, the controller controls the alarm device to generate an alarm signal.

[0021] In one optional embodiment, the cleaning machine further includes a liquid replenishment device, the controller and the liquid replenishment device are electrically connected, and the controller controls the liquid replenishment device to replenish the cleaning liquid in the cleaning tank.

[0022] Thirdly, this application provides a cleaning method for a liquid level detection device in a mask cleaning machine, the cleaning method being applied to the aforementioned mask cleaning machine, the cleaning method comprising:

[0023] The liquid level detection device is controlled to stop detecting the liquid level and the cleaning fluid in the cleaning tank is discharged.

[0024] The three-way solenoid valve is switched to the water circuit connection state and maintained for a preset flushing time, so that the flushing liquid enters the liquid level tube through the three-way solenoid valve;

[0025] After the preset flushing time is completed, the three-way solenoid valve is switched to the air path connection state so that the detection gas can enter the liquid level tube.

[0026] In an optional embodiment, before switching the three-way solenoid valve to the air-connected state after the preset rinsing time has ended, the cleaning method further includes:

[0027] After the preset rinsing time is completed and after a resting period, cleaning solution is added to the cleaning tank.

[0028] After a preset addition time, the three-way solenoid valve is switched to the air circuit connection state, and the liquid level detection device starts detecting the liquid level.

[0029] Based on the liquid level detection device provided in this application, the lower end of the liquid level tube can be inserted into the tank containing the liquid to be detected. This allows liquid in the tank to enter the liquid level tube through the lower opening, ensuring the liquid level in the tube is level with the liquid level in the tank. Then, under the control of a three-way solenoid valve, detection gas can enter the liquid level tube through the valve and the upper opening. Since the internal volume of the liquid level tube is fixed, and the lower half is occupied by the liquid in the tank, the pressure of the detection gas in the remaining upper half of the tube can be fed back to the gas supply pipe. Therefore, by sensing the internal pressure of the gas supply pipe with a pressure sensor, the unoccupied space in the liquid level tube can be calculated, and further, the liquid level in the tank can be calculated in reverse. When cleaning the liquid level tube is required, switching the three-way solenoid valve allows flushing liquid to enter the tube, achieving the effect of flushing the inner surface of the tube. Thus, when the tank contains a liquid that easily crystallizes, the liquid level detection device provided in this application can promptly remove and flush away crystals from the inner surface of the liquid level tube, preventing crystals from occupying the internal space of the liquid level tube. This avoids the pressure sensor from sensing that the internal pressure of the air supply pipe cannot accurately reflect the liquid level in the liquid level tube. Therefore, the liquid level detection device provided in this application can improve the accuracy of liquid level detection. Attached Figure Description

[0030] The accompanying drawings are intended only to illustrate and explain this application and do not limit the scope of this application.

[0031] Figure 1 This is a schematic diagram of a liquid level detection device provided in an exemplary embodiment of this application;

[0032] Figure 2 This is a schematic diagram of a liquid level tube provided in an exemplary embodiment of this application;

[0033] Figure 3 This is a schematic diagram of a cleaning machine for a mask template provided in an exemplary embodiment of this application;

[0034] Figure 4 This is another schematic diagram of a cleaning machine for a mask template provided in an exemplary embodiment of this application;

[0035] Figure 5 A flowchart illustrating a cleaning method for a liquid level detection device in a mask cleaning machine, provided as an exemplary embodiment of this application.

[0036] Explanation of reference numerals in the attached figures:

[0037] 10 - Liquid level tube, 11 - Upper opening, 12 - Lower opening;

[0038] 21 - Gas supply source, 22 - Liquid supply source;

[0039] 31-Gas supply pipe, 32-Liquid supply pipe, 33-Connecting pipe;

[0040] 41-Three-way solenoid valve, 42-First check valve, 43-Second check valve, 44-Drain valve;

[0041] 51-Controller, 52-Cleaning tank. Detailed Implementation

[0042] To provide a clearer understanding of the technical features, objectives, and effects of the embodiments of this application, the specific implementation methods of the embodiments of this application will now be described with reference to the accompanying drawings.

[0043] In this document, “illustrative” means “serving as an example, illustration or description”, and any illustration or implementation described herein as “illustrative” should not be construed as a more preferred or advantageous technical solution.

[0044] To keep the drawings concise, each drawing only schematically shows the parts relevant to this application, and they do not represent the actual structure of the product. Furthermore, to make the drawings concise and easy to understand, in some drawings, components with the same structure or function are only schematically shown as one or more, or only one or more are labeled.

[0045] Firstly, reference Figure 1 This application first provides a liquid level detection device, which includes a liquid level tube 10, an air supply source 21, a liquid supply source 22, a three-way solenoid valve 41, a connecting pipe 33, an air supply pipe 32, and a pressure sensor; wherein, the liquid level tube 10 includes an upper opening 11 and a lower opening 12, which are located at opposite ends of the liquid level tube 10; the air supply source 21 is used to provide detection gas; the liquid supply source 22 is used to provide flushing liquid; the three-way solenoid valve 41 includes a first inlet, a second inlet, and an outlet, the first inlet and the liquid supply source... 22 is connected, and the outlet of the three-way solenoid valve 41 is connected to the upper opening 11; the air supply pipe 31 is connected between the second inlet of the three-way solenoid valve 41 and the air supply source 21. By switching the three-way solenoid valve 41, the detection gas can enter the liquid level pipe 10 from the upper opening 11, or the flushing liquid can enter the liquid level pipe 10 from the upper opening 11 to flush the inner surface of the liquid level pipe 10; the pressure sensor is installed on the air supply pipe 31. When the detection gas enters the liquid level pipe 10 from the upper opening 11, the pressure sensor is used to detect the internal pressure of the air supply pipe 31.

[0046] As can be seen from the above technical solution, when using the liquid level detection device, the lower end of the liquid level tube 10 can be inserted into the tank containing the liquid to be detected. In this way, the liquid in the tank can enter the liquid level tube 10 through the lower opening 12, and the liquid level in the liquid level tube 10 is level with the liquid level in the tank. Then, under the control of the three-way solenoid valve 41, the detection gas enters the liquid level tube 10 through the three-way solenoid valve 41 and the upper opening 11. Since the internal volume of the liquid level tube 10 is fixed, and the lower half of the liquid level tube 10 is occupied by the liquid in the tank, the pressure of the detection gas in the remaining upper half of the liquid level tube 10 can be fed back to the gas supply pipe 31. Therefore, by sensing the internal pressure of the gas supply pipe 31 by the pressure sensor, the unoccupied space in the liquid level tube 10 can be calculated, and further, the liquid level in the tank can be calculated in reverse. When the level tube 10 needs cleaning, switching the three-way solenoid valve 41 can stop the supply of detection gas to the level tube 10 and allow flushing liquid to enter the level tube 10, achieving the effect of flushing the inner surface of the level tube 10. Thus, when the tank contains a liquid that easily crystallizes, the level detection device provided in this application can promptly remove and flush the crystals on the inner surface of the level tube 10, preventing crystals from occupying the internal space of the level tube 10, thereby preventing the pressure sensor from sensing that the internal pressure of the gas supply pipe 31 cannot accurately reflect the liquid level in the level tube 10. Therefore, the level detection device provided in this application can improve the accuracy of level detection.

[0047] Specifically, the switching of the three-way solenoid valve 41 refers to the switching of the valve core position. In one example, when the valve core is in the first position, the gas supply source 21 and the liquid level pipe 10 are connected, allowing nitrogen gas to flow from the gas supply source 21 into the liquid level pipe 10, thus detecting the liquid level. When the valve core switches to the second position, the gas supply source 21 and the liquid level pipe 10 are disconnected, while the liquid supply source 22 is simultaneously connected to the liquid level pipe 10, allowing flushing liquid to flow from the liquid supply source 22 into the liquid level pipe 10, achieving the effect of cleaning the inner surface of the liquid level pipe 10. This design ensures the independence and flexibility of the nitrogen gas detection and flushing liquid supply processes, improving the operating efficiency and accuracy of the liquid level detection device. In one example, the three-way solenoid valve 41 can be a two-position three-way solenoid valve 41 or a three-position three-way solenoid valve 41.

[0048] Gas supply 21 can provide nitrogen. As an inert gas, nitrogen is chemically stable and does not readily react with other substances. This ensures that during level detection, nitrogen will not adversely react with the liquid in the tank or the flushing liquid, thus maintaining the purity of the internal environment of the level tube 10. Secondly, nitrogen is non-toxic and harmless, and environmentally friendly, allowing workers to safely operate or maintain the level detection device. Furthermore, nitrogen is readily available and cost-effective, reducing the operating costs of the level detection device.

[0049] Liquid supply source 22 can provide deionized water. As a high-purity water, deionized water has an extremely low ion content, which ensures that no additional ions are introduced during the liquid level detection process, thus avoiding interference from these ions with the liquid level detection results. At the same time, deionized water also has good chemical stability and is not prone to chemical reactions with other substances, further improving the accuracy of liquid level detection.

[0050] The directional terms "upper" and "lower" in this application are used merely for descriptive convenience; that is, the end of the liquid level pipe 10 inserted into the tank is referred to as the lower end, and the end of the liquid level pipe 10 connected to the air supply source 21 is referred to as the upper end. They are not intended to limit the technical solutions in this application. Therefore, the directional terms "upper" and "lower" in this application should not be considered as a limitation on the scope of protection of this application.

[0051] In one example, the liquid level detection device may further include a connecting pipe 33, which is connected between the outlet of the three-way solenoid valve 41 and the upper opening 11 of the liquid level tube 10, so that the detection gas or flushing liquid can enter the liquid level tube 10 through the connecting pipe 33.

[0052] In one possible embodiment, the material of the level tube 10 may include polyetheretherketone (PEEK). PEEK possesses numerous excellent properties, including high temperature resistance, superior mechanical properties, good self-lubrication, strong chemical corrosion resistance, flame retardancy, and hydrolysis resistance. Therefore, even after prolonged use, the inner surface of the level tube 10 can maintain good smoothness, reducing adhesion and minimizing crystal formation on the inner surface of the tube. When the mask cleaning machine uses the level detection device provided in this application, the level tube 10 can resist the corrosion of the alkaline cleaning solution in the cleaning machine, further ensuring good smoothness of the inner surface of the level tube 10.

[0053] In one possible embodiment, reference Figure 2The lower opening 12 can penetrate the lower end face of the level tube 10. That is, the lower opening 12 is located at the lowest end of the level tube 10, so that the liquid in the tank can enter the level tube 10 through the lower opening 12 without obstruction, so as to more accurately detect the liquid level in the tank. In actual use, the lower end face of the level tube 10 can contact the bottom surface of the tank.

[0054] To prevent the flushing liquid from flowing back towards the supply source 22, in one possible embodiment, refer to Figure 1 The liquid level detection device also includes a liquid supply pipe 32 and a first check valve 42. The liquid supply pipe 32 is connected between the first inlet of the three-way solenoid valve 41 and the liquid supply source 22, and the first check valve 42 is installed on the liquid supply pipe 32. Based on this technical solution, the first check valve 42 ensures that the liquid in the liquid supply pipe 32 can only flow in one direction, from the liquid supply source 22 to the three-way solenoid valve 41, and cannot flow in the opposite direction. Thus, when the flushing liquid backflows in the tank, the first check valve 42 prevents the backflowing liquid from passing through it, thereby avoiding the problem of the flushing liquid flowing back towards the liquid supply source 22. This not only improves the stability and reliability of the liquid level detection device but also effectively protects the liquid supply source 22 from contamination and damage by the backflowing liquid.

[0055] In one possible embodiment, the liquid level detection device further includes a second check valve 43, which is installed on the air supply pipe 31 and located between the pressure sensor and the air supply source 21. Based on this technical solution, the second check valve 43 ensures that the detection gas in the air supply pipe 31 can only flow in one direction, from the air supply source 21 to the three-way solenoid valve 41, and cannot flow in the opposite direction. With this design, when the liquid level in the tank fluctuates, causing the detection gas in the liquid level pipe 10 to flow in the opposite direction towards the air supply source 21, the second check valve 43 prevents the detection gas from continuing to flow forward, thus avoiding the problem of backflow of the detection gas towards the air supply source 21. This ensures that the pressure sensor can accurately reflect the internal pressure of the air supply pipe 31, further improving the accuracy of liquid level detection.

[0056] Among them, the check valve is an automatic valve, also called a one-way valve, non-return valve, or back pressure valve. Its main function is to automatically prevent fluid backflow, relying on the flow of the medium itself to automatically open and close the valve disc. When the fluid flows in the specified direction, the valve disc opens; when the fluid flows backward, the valve disc automatically closes under the action of fluid pressure and its own gravity, preventing the medium from flowing backward.

[0057] In one possible embodiment, to enhance the structural strength of the level tube 10 and prevent it from deforming or cracking during prolonged use, the tube wall of the level tube 10 can be configured as a double-layer structure, with insulation material filling the space between the two layers. The addition of insulation material not only improves the insulation performance of the level tube 10, preventing temperature fluctuations from affecting level detection, but also further increases the mechanical strength of the level tube 10, extending its service life.

[0058] In summary, the liquid level detection device provided in this application has advantages such as simple structure, convenient operation, high detection accuracy, and good stability. It is particularly suitable for applications requiring precise liquid level control, such as cleaning machines for vapor deposition masks during thin film preparation in semiconductor manufacturing and flat panel display industries. By adopting the liquid level detection device provided in this application, problems such as inaccurate liquid level detection and susceptibility to crystallization interference in existing technologies can be effectively solved, thereby improving production efficiency and product quality.

[0059] Secondly, this application also provides a mask cleaning machine, as shown in the reference. Figure 3 The cleaning machine includes a cleaning tank 52, a controller 51, and the aforementioned liquid level detection device. The controller 51 and the three-way solenoid valve 41 of the liquid level detection device are electrically connected. The lower opening 12 of the liquid level tube 10 of the liquid level detection device is inserted into the cleaning tank 52 to detect the liquid level.

[0060] Based on the above description of the liquid level detection device, the cleaning machine provided in this application can use the controller 51 to control the switching of the three-way solenoid valve 41, and can use the liquid level detection device to detect the liquid level in the cleaning tank 52. When the cleaning machine needs to replace the cleaning fluid in the cleaning tank 52, under the control of the controller 51, after the cleaning fluid is drained, the three-way solenoid valve 41 can be switched to allow the flushing liquid to enter the liquid level tube 10, cleaning the inner surface of the liquid level tube 10 and washing away the crystals adhering to the inner surface of the liquid level tube 10. This allows the internal gas pressure of the air supply pipe 31 detected by the pressure sensor to accurately reflect the unoccupied space volume in the liquid level tube 10, thereby accurately calculating the liquid level in the cleaning tank 52. Thus, the cleaning machine provided in this application can automatically detect the liquid level and automatically clean the inner surface of the liquid level tube 10, making the liquid level detection more accurate.

[0061] In one possible embodiment, the mask cleaning machine further includes clamping components mounted on the cleaning tank 52 for holding the level tube 10. By providing the clamping components, the position of the level tube 10 relative to the cleaning tank 52 can be kept stable, preventing positional shifts in the level tube 10 due to fluctuations in the cleaning fluid during mask cleaning, thus avoiding impacts on the accuracy of level detection. Multiple clamping components can be provided, spaced apart along the axial direction of the level tube 10.

[0062] Of course, in practical applications, the lower end of the level tube 10 can be placed against the bottom of the cleaning tank 52 so as to accurately reflect the level of liquid in the aoba tank.

[0063] In one possible embodiment, reference Figure 4 The cleaning machine also includes a drain valve 44, which is installed at the outlet of the cleaning tank 52. The controller 51 is electrically connected to the drain valve 44 and is used to control the opening or closing of the drain valve 44. In this way, the controller 51 can be used to automatically control the discharge of cleaning fluid, automatically control the liquid level detection and cleaning of the inner surface of the liquid level tube 10, making the cleaning machine more automated and intelligent.

[0064] In one possible embodiment, the cleaning machine may further include a digital display device and an alarm device. The controller 51 is electrically connected to the pressure sensor, the digital display device, and the alarm device. The controller 51 calculates the current liquid level based on the pressure feedback from the pressure sensor and displays the current liquid level on the digital display device. When the current liquid level is lower than a preset threshold, the controller 51 controls the alarm device to generate an alarm signal. This technical solution allows operators to intuitively monitor the liquid level in the cleaning tank 52 via the digital display device, and the alarm signal can promptly detect when the liquid level in the cleaning tank 52 is low, allowing for timely replenishment of the cleaning fluid in the cleaning tank 52 to avoid affecting the cleaning of the mask.

[0065] In one example, the cleaning machine may include a replenishment device. The controller 51 and the corresponding replenishment device can be electrically connected. The controller 51 can control the replenishment device to replenish the cleaning fluid in the cleaning tank 52. That is, the controller 51 can automatically control the replenishment device to replenish the cleaning fluid in the cleaning tank 52 according to the liquid level.

[0066] Furthermore, the cleaning machine may also include a temperature sensor for monitoring the temperature of the cleaning fluid in the cleaning tank 52, and a heating device for heating the cleaning fluid. The temperature sensor is electrically connected to the controller 51 and can feed back the monitored temperature information to the controller 51 in real time. The controller 51 controls the heating device to heat the cleaning fluid according to a preset temperature range or temperature curve to maintain the cleaning fluid within a suitable temperature range. This design ensures that the cleaning fluid maintains a constant temperature during the cleaning process, thereby improving the cleaning effect and product quality.

[0067] In addition, the cleaning machine may also include a stirring device for agitating the cleaning solution, which is electrically connected to the controller 51. During the cleaning process, the controller 51 can control the stirring device to agitate the cleaning solution to prevent impurities or particles in the cleaning solution from settling at the bottom of the cleaning tank 52. This also increases the contact area between the cleaning solution and the mask plate, enhancing the cleaning effect. The design of the stirring device further improves the cleaning capacity and applicability of the cleaning machine.

[0068] The mask cleaning machine provided in this application can be an ultrasonic cleaner, which utilizes the cavitation effect, acceleration effect, and direct flow effect generated by ultrasound in the cleaning fluid to clean the mask. The cavitation effect forms microbubbles in the cleaning fluid, which rapidly burst, generating a powerful impact force that effectively removes dirt and particles from the mask surface. The acceleration effect causes particles in the cleaning fluid to vibrate rapidly under the action of ultrasound, increasing the number and intensity of collisions with the mask, further improving the cleaning effect. The direct flow effect promotes the circulation of the cleaning fluid within the cleaning tank, ensuring that the cleaning fluid evenly covers all parts of the mask and avoiding cleaning dead zones.

[0069] In one possible implementation, the mask cleaning machine may include multiple cleaning tanks arranged in sequence, a mask fixing fixture, and a fixture lifting and pushing mechanism. Different cleaning tanks hold different cleaning solutions and are used to perform different cleaning steps. Each cleaning tank may be equipped with an ultrasonic generator. The mask fixing fixture is used to load and fix the mask. The fixture lifting and pushing mechanism includes a feeding mechanism and a lifting mechanism. The lifting mechanism engages with two lifting rings at both ends of the top of the mask fixing fixture via hooks. The lifting mechanism lowers or lifts the mask fixing fixture, after loading the mask, into or out of the cleaning tank. The feeding mechanism propels the lifting mechanism to move horizontally, placing the mask fixing fixture into the corresponding openable and closable cleaning tank containing different types of cleaning agents. The fixture lifting and pushing mechanism is simple and flexible to operate, enabling rapid transfer of masks between multiple cleaning tanks and improving cleaning efficiency.

[0070] The cleaning tank may include an openable and closable cover, which can seal the opening of the cleaning tank during the cleaning process to prevent the cleaning fluid from splashing out. In one example, the cleaning tank includes a rectangular open tank body, a conical groove fixed to the bottom of the rectangular open tank body, a rectangular fixing frame fixed to the outer edge of the bottom of the rectangular open tank body, four support legs fixed at the four corners of the bottom of the rectangular fixing frame, a cleaning fluid replenishment pipe disposed within the rectangular open tank body, and several nozzles disposed on the cleaning fluid replenishment pipe. The tank cover and the rectangular open tank body are slidably connected and driven by a push cylinder, which can push the tank cover to slide on the rectangular open tank body, thereby opening or closing the tank opening. The drive of the end cover of the cleaning tank body is not limited to a push cylinder and can be pneumatic, hydraulic, or electric. The side walls and bottom of the cleaning tank can be made of corrosion-resistant and easy-to-clean materials to meet the special requirements of different cleaning fluids and extend the service life of the cleaning machine. The design of the mask fixing fixture takes into account the shape and size of the mask to ensure that the mask remains stable during the cleaning process and avoids scratches or damage during the cleaning process.

[0071] In one example, the cleaning solution consists of clean and non-cleaning agents, and the mask cleaning machine can be designed to include four sequentially arranged cleaning tanks. In the first cleaning tank, the proportion of non-cleaning agents can be relatively high, while the proportion of cleaning agents can gradually increase in the subsequent three tanks. In the last cleaning tank, the cleaning solution can consist entirely of cleaning agents. This design helps to conserve the amount of cleaning agents used and prevents organic materials from remaining on the mask. Specifically, the cleaning solution in the tank should be selected according to the type of contaminants on the mask. For example, for organic contaminants such as oil, the cleaning solution can be tetramethylammonium hydroxide solution, which can effectively dissolve the contaminants on the mask.

[0072] In one example, the cleaning tank may also be equipped with four mask holders for placing the masks. These holders are positioned at the four corners of the masks to be cleaned. The design of the mask holders ensures the stability of the masks during cleaning, preventing shaking or misalignment from affecting the cleaning effect. Each mask holder can be fine-tuned according to the actual size of the mask to ensure full contact between the mask and the cleaning solution. Furthermore, the surface of the mask holders is made of corrosion-resistant and easy-to-clean materials, facilitating subsequent maintenance and cleaning, and effectively extending the service life of the equipment. During cleaning, the mask holders float up and down with the change in the level of the cleaning solution in the tank, always keeping the mask in the optimal cleaning position.

[0073] In summary, the mask cleaning machine provided in this application, by combining components such as a liquid level detection device, a controller, a temperature sensor, a heating device, and a stirring device, achieves accurate detection of the cleaning fluid level, constant temperature control, and automation and intelligence of the cleaning process. The temperature sensor, liquid replenishment device, heating device, stirring device, digital display device, and alarm device in this application are not shown in the figures.

[0074] Thirdly, this application also provides a cleaning method for a liquid level detection device in a mask cleaning machine, the cleaning method being applied to the aforementioned mask cleaning machine, with reference to... Figure 5 The cleaning method includes:

[0075] S601, the liquid level detection device is controlled to stop detecting the liquid level and the cleaning liquid in the cleaning tank is discharged;

[0076] S602, control the three-way solenoid valve to switch to the water circuit connection state and maintain the preset flushing time, so that the flushing liquid enters the liquid level tube through the three-way solenoid valve;

[0077] S603, after the preset flushing time is completed, control the three-way solenoid valve to switch to the gas path connection state so that the detection gas enters the liquid level tube.

[0078] Specifically, the controller 51 can simultaneously generate a drain signal and a stop detection signal. The drain signal controls the drain valve 44 on the cleaning tank 52 to switch to the open state, and the stop detection signal controls the pressure sensor to stop detecting the internal pressure of the air supply pipe 31, thereby causing the liquid level detection device to stop detecting the liquid level. Switching the three-way solenoid valve to the water path connection state means that the channel between the liquid supply source 22 and the opening 11 on the liquid level pipe 10 is opened, allowing flushing liquid to enter the liquid level pipe 10. Switching the three-way solenoid valve to the air path connection state means that the channel between the air supply source 21 and the opening 11 on the liquid level pipe 10 is opened, allowing detection gas to enter the liquid level pipe 10. After a preset flushing time, the flushing liquid can wash away the crystals on the inner wall of the liquid level pipe; then the detection gas can be introduced into the liquid level pipe again to start detecting the liquid level. In this way, the crystals on the inner wall of the liquid level pipe can be removed without removing the liquid level pipe 10 from the cleaning machine, improving operational convenience.

[0079] Furthermore, after cleaning the liquid level tube, the controller can close the drain valve, allowing cleaning fluid to be added back to the cleaning tank, and control the pressure sensor to start detecting the internal pressure of the air supply pipe 31, thereby enabling the liquid level detection device to start detecting the liquid level.

[0080] Specifically, before switching the three-way solenoid valve to the air-connected state after the preset rinsing time has ended, the cleaning method further includes:

[0081] After the preset rinsing time is completed and after a resting period, cleaning solution is added to the cleaning tank.

[0082] After a preset addition time, the three-way solenoid valve is switched to the air circuit connection state, and the liquid level detection device starts detecting the liquid level.

[0083] Based on the above technical solution, a set idle time is provided to allow time for the flushing liquid to drain from the cleaning tank. That is, after the idle time, the flushing liquid is drained from the cleaning tank before the cleaning liquid is refilled, preventing the cleaning liquid and flushing liquid from mixing. Specifically, after the idle time, the drain valve can be closed first, and then the replenishment device can be controlled to add cleaning liquid to the cleaning tank. After the preset addition time, the liquid level is then monitored, thus avoiding false alarms.

[0084] In practical applications, cleaning the level tube and changing the cleaning fluid can be performed together; in other words, the level tube can be cleaned while changing the cleaning fluid. One workflow for changing the cleaning fluid in the mask cleaning machine provided in this application can be as follows:

[0085] The controller 51 generates a drain signal and a stop detection signal. The drain valve 44 switches to the open state according to the drain signal, so that the cleaning liquid in the cleaning tank 52 is discharged. The pressure sensor stops detecting the internal pressure of the air supply pipe 31 according to the stop detection signal.

[0086] After the cleaning fluid is drained, the controller 51 sends a liquid supply signal to the three-way solenoid valve 41, causing the three-way solenoid valve 41 to switch, and the flushing liquid enters the liquid level tube 10 to flush the inner surface of the liquid level tube 10.

[0087] After the preset flushing time is completed, the controller 51 sends an air supply signal to the three-way solenoid valve 41, causing the three-way solenoid valve 41 to switch and detect the gas entering the liquid level tube 10.

[0088] After the preset rinsing time has ended and the idle time has passed, the drain valve is closed and the replenishment device is used to add cleaning fluid to the cleaning tank.

[0089] After a preset addition time, the three-way solenoid valve is switched to the air circuit connection state, and the liquid level detection device starts detecting the liquid level.

[0090] Through the above technical solution, the controller 51 can simultaneously generate a drain signal and a stop detection signal. The drain signal controls the drain valve 44 on the cleaning tank 52 to switch to the open state, and the stop detection signal controls the pressure sensor to stop detecting the internal pressure of the air supply pipe 31, thereby causing the liquid level detection device to stop detecting the liquid level. Switching the three-way solenoid valve to the water circuit connection state means that the channel between the liquid supply source 22 and the opening 11 on the liquid level pipe 10 in the three-way solenoid valve is opened, allowing flushing liquid to enter the liquid level pipe 10. Switching the three-way solenoid valve to the air circuit connection state means that the channel between the air supply source 21 and the opening 11 on the liquid level pipe 10 in the three-way solenoid valve is opened, allowing detection gas to enter the liquid level pipe 10. After a preset flushing time, the flushing liquid can wash away the crystals on the inner wall of the liquid level pipe; then the detection gas can be introduced into the liquid level pipe again to start detecting the liquid level. In this way, the crystals on the inner wall of the liquid level pipe can be removed without removing the liquid level pipe 10 from the cleaning machine, improving the convenience of operation. Furthermore, by setting an idle time, sufficient time is allowed for the flushing liquid to drain from the cleaning tank. That is, after the idle time, the flushing liquid is drained from the cleaning tank before cleaning fluid is refilled, preventing the cleaning fluid and flushing liquid from mixing. Specifically, after the idle time, the drain valve can be closed first, and then the replenishment device can be controlled to add cleaning fluid to the cleaning tank. After the preset addition time, the liquid level is then monitored, thus avoiding false alarms.

[0091] Before generating the drain signal, the controller 51 can estimate the draining time of the cleaning fluid based on the current liquid level fed back by the liquid level detection device, and add a reserve time to the estimate as the draining time. When the draining time ends, the cleaning machine can send a liquid supply signal to the three-way solenoid valve 41, and the three-way solenoid valve 41 switches to the water circuit connection state. At this time, the channel between the liquid supply source and the cleaning tank is opened, and the flushing liquid can enter the liquid level pipe.

[0092] In addition, to ensure the accuracy and stability of the liquid level detection device, it can be calibrated and maintained regularly. The calibration process may include checking for blockages or wear in the liquid level tube, verifying the accuracy of the pressure sensor, and adjusting the display precision of the digital display. Regular calibration and maintenance allow for the timely detection and resolution of potential problems, ensuring the liquid level detection device is always in good working order.

[0093] Furthermore, to further enhance the automation and intelligence of the mask cleaning machine, the liquid level detection device can be integrated with other related equipment or systems. For example, the liquid level detection device can be integrated with a replenishment device, a heating device, and a stirring device to form a complete automated cleaning system. This system can automatically adjust the replenishment volume, heating temperature, and stirring speed based on parameters such as the liquid level, temperature, and stirring conditions of the cleaning solution, thereby achieving a more precise and efficient cleaning process.

[0094] It should be noted that, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.

[0095] It should be understood that although specific embodiments of this application have been described in detail with reference to the accompanying drawings, this should not be construed as limiting the scope of protection of this application. Various modifications and variations that can be made by those skilled in the art without inventive effort within the scope described in the claims still fall within the scope of protection of this application. Although this specification describes various embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0096] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A liquid level detection device, characterized in that, The liquid level detection device includes: A liquid level tube (10) includes an upper opening (11) and a lower opening (12), the upper opening (11) and the lower opening (12) being located at opposite ends of the liquid level tube (10); Gas supply source (21) is used to provide detection gas; Liquid supply source (22) is used to provide flushing liquid; A three-way solenoid valve (41) includes a first inlet, a second inlet, and an outlet. The first inlet is connected to the liquid supply source (22), and the outlet of the three-way solenoid valve (41) is connected to the upper opening (11). A gas supply pipe (31) is connected between the second inlet of the three-way solenoid valve (41) and the gas supply source (21). By switching the three-way solenoid valve (41), the detection gas can enter the liquid level pipe (10) from the upper opening (11), or the flushing liquid can enter the liquid level pipe (10) from the upper opening (11) to flush the inner surface of the liquid level pipe (10). A pressure sensor is installed on the gas supply pipe (31) to detect the internal pressure of the gas supply pipe (31) when the detection gas enters the liquid level pipe (10) from the upper opening (11).

2. The liquid level detection device according to claim 1, characterized in that, The material of the level tube (10) includes polyetheretherketone.

3. The liquid level detection device according to claim 1, characterized in that, The lower opening (12) penetrates the lower end face of the liquid level tube (10).

4. The liquid level detection device according to claim 1, characterized in that, The liquid level detection device also includes a liquid supply pipe (32) and a first check valve (42). The liquid supply pipe (32) is connected between the first inlet of the three-way solenoid valve (41) and the liquid supply source (22). The first check valve (42) is installed on the liquid supply pipe (32).

5. The liquid level detection device according to claim 1, characterized in that, The liquid level detection device also includes a second check valve (43), which is installed on the air supply pipe (31) and is located between the pressure sensor and the air supply source (21).

6. A mask plate cleaning machine, characterized in that, The cleaning machine includes a cleaning tank (52), a controller (51), and a liquid level detection device according to any one of claims 1-5. The controller (51) and the three-way solenoid valve (41) of the liquid level detection device are electrically connected. The lower opening (12) of the liquid level tube (10) of the liquid level detection device is inserted into the cleaning tank (52) to detect the liquid level.

7. The mask cleaning machine according to claim 6, characterized in that, The mask cleaning machine also includes a clamping component, which is installed on the cleaning tank (52) and is used to clamp the liquid level tube (10).

8. The mask cleaning machine according to claim 6, characterized in that, The cleaning machine also includes a drain valve, which is installed at the outlet of the cleaning tank (52). The controller (51) is electrically connected to the drain valve and is used to control the drain valve to open or close.

9. The mask cleaning machine according to claim 6, characterized in that, The cleaning machine also includes a digital display device and an alarm device. The controller (51) is electrically connected to the pressure sensor, the digital display device, and the alarm device. The controller (51) calculates the current liquid level based on the pressure fed back by the pressure sensor and displays the current liquid level on the digital display device; When the current liquid level is lower than a preset threshold, the controller (51) controls the alarm device to generate an alarm signal.

10. The mask cleaning machine according to claim 6, characterized in that, The cleaning machine also includes a liquid replenishment device. The controller (51) is electrically connected to the liquid replenishment device, and the controller (51) controls the liquid replenishment device to replenish the cleaning liquid in the cleaning tank (52).

11. A cleaning method for a liquid level detection device in a mask plate cleaning machine, characterized in that, The cleaning method is applied to the mask cleaning machine according to any one of claims 6-10, and the cleaning method includes: The liquid level detection device is controlled to stop detecting the liquid level and the cleaning fluid in the cleaning tank is discharged. The three-way solenoid valve is switched to the water circuit connection state and maintained for a preset flushing time, so that the flushing liquid enters the liquid level tube through the three-way solenoid valve; After the preset flushing time is completed, the three-way solenoid valve is switched to the air path connection state so that the detection gas can enter the liquid level tube.

12. The cleaning method for the liquid level detection device in the mask plate cleaning machine according to claim 11, characterized in that, Before the preset rinsing time ends and the three-way solenoid valve is switched to the air-connected state, the cleaning method further includes: After the preset rinsing time is completed and after a resting period, cleaning solution is added to the cleaning tank. After a preset addition time, the three-way solenoid valve is switched to the air circuit connection state, and the liquid level detection device starts detecting the liquid level.

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