LCD rubbing process humidifier circulation system and humidity control method

Abstract

The application discloses a LCD rubbing process humidifier circulating system, which comprises a humidifier circulating unit, an environment detecting unit and a control unit, the humidifier circulating unit is arranged near a rubbing workshop, and comprises a pure water storage tank, a humidifying module, a dehumidifying module, a HEPA filter and a circulating fan; one end of the humidifying module is connected with the pure water storage tank through a pipeline, the other end is connected with the HEPA filter inlet pipeline, the HEPA filter inlet is also connected with the dehumidifying module through a pipeline, the HEPA filter outlet is connected with the circulating fan through a pipeline, and the circulating fan outlet is connected with a plurality of nozzles through a pipeline; and the nozzles are fixedly arranged in the rubbing workshop. The application can precisely control the rubbing environment humidity, make the PI layer surface form a conductive path to promote the charge leakage, reduce the surface potential from several kV / cm to 500 V / cm or below, make the potential uniformity CV be less than or equal to 15%, and reduce the electrostatic related defect rate by more than 60%.

Description

Technical Field

[0001] This invention relates to the field of liquid crystal display panel manufacturing technology, specifically to a humidifier circulation system and humidity control method for an LCD friction process. Background Technology

[0002] In the pre-processing of LCD manufacturing, the rubbing process is a crucial step involving the directional rubbing of the PI layer with a felt cloth to create a pretilt angle for the liquid crystal molecules. The pretilt angle and rubbing depth are two core physical parameters that measure the quality of the rubbing process, directly determining whether the liquid crystal molecules can align neatly as designed, thus affecting the screen's brightness, contrast, and response speed. Existing rubbing processes suffer from the following key problems in actual production: 1. Severe Static Electricity Accumulation: During the friction process, the plush cloth rubs against the PI layer at high speed (1200 RPM), generating a large amount of static electricity through mechanisms such as contact charging, separation charging, and frictional heat generation. This leads to the accumulation of charge on the PI layer surface, affecting the alignment of liquid crystal molecules. In severe cases, electrostatic discharge can directly break down the PI layer, causing irreversible device damage.

[0003] 2. Dust adsorption problem is prominent: After friction, the electrostatic field strength on the substrate surface can reach several kV / cm. The electrostatic field has a strong adsorption force on dust and fibers in the air, which can easily cause defects such as pinholes and scratches on the substrate, directly affecting the panel quality.

[0004] 3. Friction uniformity fluctuates with the seasons: Seasonal humidity changes (especially in dry winter when humidity can drop below 30%RH) lead to unstable friction quality, increased pretilt angle deviation, and decreased process capability index CPK, which cannot meet the requirements of high-precision manufacturing.

[0005] 4. Severe loss in yield: The defect rate caused by electrostatic discharge damage and dust contamination is about 3-5%, and electrostatic-related customer complaints occur frequently, which seriously affects production efficiency and economic benefits.

[0006] 5. Existing static elimination measures (such as ion static bars) have limited effectiveness: Ion static bars can only eliminate static electricity accumulated on the substrate surface, but cannot suppress the generation of static electricity during the friction process from the source, and the ion balance is unstable.

[0007] 6. Lack of closed-loop humidity control: The existing friction workshop relies solely on the air conditioning system to regulate the overall temperature and humidity, which cannot accurately control the humidity of the local environment in the friction machine cavity. The humidity fluctuates greatly (above ±10%RH) and cannot automatically adjust the humidity according to the static state.

[0008] Therefore, there is an urgent need to develop a dedicated humidification circulation system for LCD friction processes that can suppress static electricity generation at the source, achieve precise closed-loop humidity control, and adapt to seasonal humidity changes. Summary of the Invention

[0009] The purpose of this invention is to overcome the shortcomings of the prior art and provide a humidifier circulation system and humidity control method for LCD friction process. By establishing an independent humidifier circulation system around the friction machine, precise closed-loop control of the humidity of the friction environment can be achieved, thereby suppressing static electricity generation, reducing dust adsorption, stabilizing friction quality, and significantly improving the yield of the friction process.

[0010] To achieve the above objectives, the present invention provides the following technical solution: A humidifier circulation system for an LCD friction process includes a humidifier circulation unit, an environmental monitoring unit, and a control unit. The humidifier circulation unit is located near the friction workshop and includes a pure water storage tank, a humidification module, a dehumidification module, a HEPA filter, and a circulating fan. One end of the humidification module is connected to the pure water storage tank pipeline, and the other end is connected to the HEPA filter inlet pipeline. The HEPA filter inlet is also connected to the dehumidification module via a pipeline. The HEPA filter outlet is connected to the circulating fan pipeline, and the circulating fan outlet is connected to several nozzles via a pipeline. The nozzles are fixedly installed. Above the friction machine in the friction workshop, the environmental detection unit includes multiple temperature and humidity sensors distributed in the friction area of ​​the friction machine, used to collect environmental temperature and humidity data of the friction area in real time. The control unit is connected to the humidification module, dehumidification module, circulating fan and temperature and humidity sensors respectively. According to the deviation between the temperature and humidity data collected by the temperature and humidity sensors and the preset target humidity, the control unit automatically adjusts the output power of the humidification module, the start and stop of the dehumidification module and the speed of the circulating fan, so as to control the environmental humidity of the friction area within the target humidity ±3%RH range, and the humidity control response time is ≤3 minutes.

[0011] Preferably, the pure water storage tank uses ultrapure water with a resistivity ≥18.25MΩ・cm as the humidification water source and is equipped with a UV disinfection device to prevent microbial growth. The humidification module uses an electrode-type humidifier with a humidification capacity ≥10kg / h and a humidity control accuracy of ±2%RH. The dehumidification module uses an industrial dehumidifier with a dehumidification capacity ≥20L / day. The HEPA filter has a filtration grade of H13 and a filtration efficiency ≥99.97%. The circulating fan uses a frequency converter-controlled fan with an air volume of 1000-1500m³ / h.

[0012] Preferably, the nozzles are evenly distributed above the friction machine and face upwards, and the vertical distance between the nozzles and the friction machine is controlled within 0.3-0.5m.

[0013] Preferably, there are 4-6 sets of multi-point temperature and humidity sensors, distributed in the upper, lower, left and right positions of the friction area. The accuracy of the temperature and humidity sensors is ±0.5%RH. The control unit is a PLC controller and is equipped with a human-machine interface.

[0014] Preferably, the target humidity is set according to the season, with the target humidity set at 55%RH in winter and 50%RH in summer.

[0015] Preferably, the humidifier circulation system for the LCD friction process further includes a safety protection unit, which includes a humidity alarm device, a leakage protection device, and an emergency drainage device. The humidity alarm device is equipped with an alarm humidity threshold, which is set to 65%RH.

[0016] This invention also provides a humidity control method for the LCD friction process, employing the aforementioned LCD friction process humidifier circulation system, comprising the following steps: S1. Parameter settings: The target humidity and target temperature of the friction environment are set according to the season via the PLC controller. The target humidity in summer is set to 50%RH to enable automatic dehumidification, and the target humidity in winter is set to 55%RH to enhance humidification. The alarm humidity threshold is set to 65%RH, the safe humidity threshold is set to 60%RH, and the target temperature is set to 22℃.

[0017] S2. Real-time monitoring: Real-time collection of ambient temperature and humidity data at multiple locations above, below, left, and right of the friction area using multi-point temperature and humidity sensors and transmission to the PLC controller. S3. Closed-loop regulation: The PLC controller calculates the deviation between the target humidity value and the measured humidity value. When the measured humidity is lower than 95% of the target humidity value, the output power of the humidifier and the speed of the circulating fan are increased. When the measured humidity is higher than 105% of the target humidity value, the dehumidifier is started and the power of the humidifier is reduced. The humidity control keeps the humidity fluctuation range in the friction area within ±3%RH of the target humidity. The humidity control response time is ≤3 minutes. S4. Optimization of process parameters: An orthogonal experiment on humidity-friction quality was conducted with four factors and three levels: target humidity, humidity fluctuation range, circulating air volume, and plush fabric tension. The optimal parameter combination was determined, and the pretilt angle deviation was controlled within ±0.3° and the friction depth was controlled within 20-50nm. A humidity-surface potential-pretilt angle correlation database was established to achieve traceability of process parameters. S5, Safety Interlock: (1) When the measured humidity exceeds the alarm humidity threshold, the emergency dehumidification program is triggered and an alarm signal is issued. If the measured humidity does not drop below the safe humidity threshold within the specified time, the shutdown command is executed. (2) Set a high humidity exposure timer to record the cumulative time when the measured humidity exceeds the safe humidity threshold for a single consecutive time. If the time exceeds 4 hours, even if the alarm humidity threshold is not reached, the system will still be judged as an abnormal working condition and will trigger the emergency dehumidification program and issue an alarm signal. If the measured humidity does not drop below the safe humidity threshold within the specified time, the shutdown command will be executed. (3) Simultaneously perform leakage current detection and grounding status monitoring to ensure electrical safety; S6. Air purification: The circulating air is filtered through an H13 grade HEPA filter throughout the entire process, and the humidification water source uses ultrapure water with a resistivity ≥18.25MΩ·cm and is regularly disinfected with UV.

[0018] Preferably, in step S3, triple electrostatic suppression is achieved through humidity control: (1) Improved surface conductivity: Moisture adsorbed on the surface of the PI layer forms a conductive path, promotes charge leakage, and makes the time for the surface potential to decay to within 500V / cm ≤60 seconds. (2) Enhanced air ionization: Increased humidity increases the degree of air ionization and accelerates charge neutralization; (3) Dust suppression: Increase ambient humidity to reduce dust flying and electrostatic adsorption, and control the number of ≥3μm particles to ≤5 per piece; Preferably, the humidity control method for the LCD friction process further includes an intelligent extension step: (1) Incorporate humidity control data into the SPC statistical process control system and establish a correlation model between humidity and friction quality; (2) Adopt AI predictive control algorithm to predict humidity fluctuations based on historical data and environmental change trends, and adjust the humidification or dehumidification power in advance; (3) It is linked with auxiliary static removal equipment such as ion static bar to form a comprehensive static protection system.

[0019] Compared with the prior art, the beneficial effects of the present invention are: 1. Suppressing static electricity generation at the source: This invention precisely controls the humidity of the friction environment, forming a conductive path on the PI layer surface to promote charge leakage. The surface potential is reduced from several kV / cm to less than 500V / cm, the potential uniformity CV ≤ 15%, and the static electricity-related defect rate is reduced by ≥ 60%. Compared with the existing technology that only increases humidity but lacks precise control, this invention achieves quantitative and precise control of humidity, resulting in a significant static electricity suppression effect.

[0020] 2. Significantly reduces dust adsorption: Increased humidity inhibits dust flying and electrostatic adsorption, reducing the number of ≥3μm particles by ≥50% from the current level, controlling it to ≤5 particles / piece, and greatly reducing defects such as pinholes and scratches.

[0021] 3. Eliminate seasonal quality fluctuations: Closed-loop control stabilizes humidity within the target humidity range, with bidirectional adjustment of humidification and dehumidification, completely eliminating the problem of unstable friction quality caused by dry winters (humidity as low as 30%RH) and high summer humidity (60-70%RH), and improving the process capability index CPK from <1.0 to ≥1.33.

[0022] 4. Significantly improved yield: The yield of the friction process is improved by ≥3 percentage points, the rework rate is significantly reduced from 3-5%, and customer complaints related to static electricity are reduced by 50%.

[0023] 5. Significant economic benefits: Equipment investment is approximately RMB 245,000-360,000, annual operating costs are approximately RMB 31,000-45,000, annual revenue is estimated at RMB 1,250,000-1,900,000, investment payback period is only 2-3 months, and ROI reaches 350-650%.

[0024] 6. Strong system compatibility: The humidifier circulation system can be installed independently around the friction machine, occupying a space of about 5-8 square meters. It does not affect the existing production line layout and logistics, and can be used in conjunction with existing static elimination measures such as ion electrostatic bars. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the humidifier's circulation system; Figure 2 This is a block diagram of the humidity closed-loop control logic. Detailed Implementation

[0026] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. Example

[0027] This embodiment is applied to the friction process of an LCD panel production line during the summer.

[0028] This embodiment uses the LCD friction process humidifier circulation system described in this invention, such as... Figure 1As shown, the system includes a humidifier circulation unit, an environmental monitoring unit, and a control unit. The humidifier circulation unit is located near the friction workshop and includes a pure water storage tank, a humidification module, a dehumidification module, a HEPA filter, and a circulating fan. One end of the humidification module is connected to the pure water storage tank pipeline, and the other end is connected to the HEPA filter inlet pipeline. The HEPA filter inlet is also connected to the dehumidification module via a pipeline, and the HEPA filter outlet is connected to the circulating fan pipeline. Several nozzles are connected to the circulating fan outlet via a pipeline. The nozzles are fixedly installed above the friction machine in the friction workshop. The environmental monitoring unit includes multi-point temperature and humidity sensors distributed in the friction area of ​​the friction machine to collect real-time environmental temperature and humidity data of the friction area. The control unit is connected to the humidification module, the dehumidification module, the circulating fan, and the temperature and humidity sensors. Based on the deviation between the temperature and humidity data collected by the temperature and humidity sensors and the preset target humidity, the control unit automatically adjusts the output power of the humidification module, the start and stop of the dehumidification module, and the speed of the circulating fan to control the environmental humidity of the friction area within the target humidity ±3%RH range, with a humidity control response time ≤3 minutes.

[0029] The pure water storage tank uses ultrapure water with a resistivity ≥18.25MΩ・cm as the humidification water source. This water quality prevents impurities from remaining on the PI layer surface after evaporation, thus preventing ion contamination. A UV disinfection device (wavelength 254nm, irradiance ≥30μW / cm²) is installed to periodically circulate and sterilize the stored water, preventing microbial growth that could clog the humidifier nozzles or adhere to the substrate surface with steam. The humidification module uses an electrode-type humidifier with a humidification capacity of 12kg / h and a humidity control accuracy of ±2%RH. Its output power is steplessly adjustable from 0 to 100% via a PLC and solid-state relay, achieving precise and continuous control of the humidification capacity. The dehumidification module uses an industrial dehumidifier with a dehumidification capacity of 25L / day, featuring a built-in compressor and evaporator. It removes excess moisture from the circulating air through condensation. When the PLC determines that the ambient humidity is too high, it activates the dehumidification module, sending the dried air into the HEPA filter inlet. The dehumidification module has an independent duct switching valve, interlocked with the humidification module to prevent energy waste caused by simultaneous operation of humidification and dehumidification. The HEPA filter has an H13 filtration rating and a filtration efficiency of ≥99.97%. This filter is installed after the confluence of the humidification and dehumidification modules and before the circulating fan, ensuring that the air supplied to the workshop undergoes high-efficiency filtration after humidity adjustment, removing any particles, microorganisms, and trace impurities that may be carried during humidification. Differential pressure sensors are installed at both ends of the HEPA filter. When the differential pressure exceeds 1.5 times the initial differential pressure, the PLC triggers a replacement reminder to ensure continuous effective filtration. The circulating fan uses a frequency converter control, with an air volume of 1000-1500 m³ / h. The speed is adjusted in real time by the PLC according to humidity deviation and workshop load.

[0030] Four nozzles are evenly distributed above the friction machine, facing upwards. This upward arrangement allows the steam to diffuse upwards first and then naturally sink, preventing high-speed steam from directly impacting the friction cloth or substrate surface. This prevents localized over-humidity or uneven temperature and creates a localized microclimate isolation layer, isolating the friction chamber from large-scale humidity fluctuations caused by the workshop's air conditioning system and locking in an independent humidity environment. The vertical distance between the nozzles and the friction machine is controlled within 0.4m. 0.4m is a golden critical distance determined through simulation verification and extensive experiments. This distance ensures that the steam can quickly reach the substrate surface (wet retention time ≤ 15 seconds) while providing sufficient buffer space for the PID algorithm to adjust smoothly and achieve rapid convergence.

[0031] Four sets of multi-point temperature and humidity sensors are distributed around the friction area, offset from the nozzles, at a height of approximately 0.3m above the friction cloth surface. The sensors have an accuracy of ±0.5%RH, a response time of ≤15 seconds, and collect data every 100ms, uploading it to the PLC. This multi-point distribution eliminates measurement errors that may arise from a single measuring point, accurately reflecting the overall humidity distribution of the friction area and providing a reliable basis for closed-loop control. The control unit is a PLC controller with a human-machine interface. The PLC incorporates a PID control algorithm, receiving humidity signals from the four sensors. After median filtering, the average value is taken as the measured humidity value. The PLC compares the measured value with the preset target humidity, calculates the deviation and the rate of change of deviation, and outputs control signals to the power regulator of the humidification module, the start / stop relay of the dehumidification module, and the frequency converter of the circulating fan through PID calculation. The PID parameters (proportional gain Kp, integral time Ti, derivative time Td) are tuned on-site to ensure the system has a fast response (≤3 minutes to reach steady state) and no overshoot oscillation.

[0032] The humidifier circulation system for the LCD friction process also includes a safety protection unit, which includes a humidity alarm device, a leakage protection device, and an emergency drainage device. The humidity alarm device has an alarm humidity threshold and is linked to the production line's central monitoring system. When the measured humidity exceeds the alarm humidity threshold for more than 10 seconds, the system automatically triggers an audible and visual alarm and displays a fault message on the human-machine interface. At the same time, the PLC executes an emergency dehumidification program (forcibly starting the dehumidification module and shutting down the humidification module). If the humidity does not drop below the safe humidity threshold within 2 minutes, a shutdown command is executed to prevent the high humidity environment from causing irreversible damage to the friction quality.

[0033] The humidity control method of this embodiment has the following control logic block diagram: Figure 2 As shown, it includes the following steps: S1. Parameter settings: Set the target humidity to 50%RH, the alarm humidity threshold to 65%RH, the safe humidity threshold to 60%RH, and the target temperature to 22℃ through the human-machine interface. The temperature is maintained by the workshop's central air conditioning. This system only monitors but does not actively adjust the temperature to avoid conflict with the air conditioning system.

[0034] S2. Real-time monitoring: Real-time collection of ambient temperature and humidity data at multiple locations above, below, left, and right of the friction area using multi-point temperature and humidity sensors and transmission to the PLC controller. S3. Closed-loop regulation: The PLC controller calculates the deviation between the target humidity value and the measured humidity value. When the measured humidity is lower than 95% of the target humidity value (47.5%RH), the PID outputs a positive deviation signal, increasing the humidifier output power and the circulating fan speed to quickly replenish the friction area with humid air. When the measured humidity is higher than 105% of the target humidity value (52.5%RH), the PID outputs a negative deviation signal, starting the dehumidifier and reducing the humidifier power (gradually reducing it until it stops if the humidifier is already running), while maintaining the fan at a moderate speed to promote the circulation of dry air. Through the above bidirectional humidity control regulation, the humidity fluctuation range of the friction area is controlled within ±3%RH of the target humidity, and the humidity control response time from humidity deviation to recovery to steady state is ≤3 minutes. Triple static electricity suppression is achieved through humidity control: (1) Improved surface conductivity: Moisture adsorbed on the surface of the PI layer forms a conductive path, promotes charge leakage, and makes the time for the surface potential to decay to within 500V / cm ≤60 seconds. Precisely controlled ambient humidity causes the PI layer surface to adsorb a certain amount of water, forming a continuous water molecule film. This water film provides an ion conduction pathway, promoting the leakage of static charges generated by friction along the surface. Experiments showed that the surface potential decreased from 3000-5000 V / cm in the dry state to within 500 V / cm, and the time for the surface potential to decay to within 500 V / cm was ≤60 seconds, effectively avoiding the risk of discharge breakdown caused by charge accumulation.

[0035] (2) Enhanced air ionization: Increased humidity increases the degree of air ionization and accelerates charge neutralization; Under moderate humidity, the water molecule content in the air increases, and the strong electric field generated during friction makes it easier for water molecules to ionize, generating more free ions (H⁺ and OH⁻). These ions can quickly neutralize opposite charges on the substrate surface and the friction cloth, accelerating static electricity elimination from the gas phase path, which complements surface leakage.

[0036] (3) Dust suppression: Increase ambient humidity to reduce dust flying and electrostatic adsorption, and control the number of ≥3μm particles to ≤5 per piece; When the ambient humidity is maintained at around 50%RH, the air is relatively humid. Dust particles absorb moisture, increase in mass, and settle faster, making them less likely to remain suspended for long periods. At the same time, the electrostatic field strength on the substrate surface decreases, significantly weakening the electrostatic adsorption force on micro-dust. Actual measurements show that the number of particles ≥3μm is controlled to ≤5 per piece, far superior to the 15~20 per piece without humidification.

[0037] S4. Process Parameter Matching Optimization: To obtain the best friction quality under summer conditions, this invention conducts an orthogonal experiment on humidity-friction quality with four factors and three levels: target humidity (47.5%, 50%, 52.5%), humidity fluctuation range (±1%, ±2%, ±3%), circulating air volume (800m³ / h, 1000m³ / h, 1200m³ / h), and plush cloth tension (140N, 150N, 160N). A total of 9 sets of experiments were conducted. In each set of experiments, the pretilt angle of the substrate after friction (measured by crystal rotation method) and the friction depth (measured by atomic force microscopy) were measured. Through range analysis and variance analysis of the orthogonal experimental results, the optimal parameter combination for summer was determined to be: target humidity 50%RH, humidity fluctuation range ±2%, circulating air volume 1000m³ / h, and plush cloth tension 150N. Under this combination, the pretilt angle deviation is stable within ±0.3°, and the friction depth is controlled within the range of 20-50nm. Meanwhile, the humidity setpoint, actual humidity fluctuation curve, surface potential decay curve, and corresponding pretilt angle data for each experiment are entered into the database to establish a "humidity-surface potential-pretilt angle" related database, enabling traceability and rapid optimization of process parameters during subsequent mass production.

[0038] S5, Safety Interlock: (1) When the measured humidity exceeds the alarm humidity threshold (65%RH), the emergency dehumidification program is triggered (the dehumidification module is forcibly started and the humidification module is turned off), and an alarm signal is issued. If the measured humidity does not drop below the safe humidity threshold (60%RH) within 2 minutes, the shutdown command is executed to prevent excessive humidity from causing the plush cloth to absorb water, expand and knot, and the PI layer pretilt angle to be unstable, which would affect the friction quality. (2) Set a high humidity exposure timer to record the cumulative time when the measured humidity exceeds the safe humidity threshold (60%RH) for a single consecutive time. If the time exceeds 4 hours, even if the alarm humidity threshold (65%RH) is not reached, the system will be judged as an abnormal condition and the emergency dehumidification program will be triggered and an alarm signal will be issued. If the measured humidity does not drop below the safe humidity threshold (60%RH) within 2 minutes, the shutdown command will be executed to avoid the long-term high humidity from affecting the PI layer. (3) Simultaneously perform leakage current detection and grounding status monitoring to ensure electrical safety; S6. Air Purification: During system operation, the circulating air is filtered through an H13-grade HEPA filter throughout the entire process. Whether it is humidifying steam or dehumidified dry air, it must pass through this filter before entering the circulating fan and nozzles to ensure that the concentration of particulate matter in the air delivered to the friction area meets the ISO 5 cleanliness requirements. The humidification water source uses ultrapure water with a resistivity ≥18.25MΩ·cm and is regularly disinfected with UV light every month to avoid microbial growth and particulate contamination in a high-humidity environment.

[0039] Before the implementation of this embodiment, due to the high temperature and humidity environment in summer, the overall humidity of the workshop fluctuated greatly due to the influence of the air conditioning system. The humidity inside the friction machine cavity fluctuated between 55-70%RH. The humidity control accuracy in some areas of the friction machine was poor, which easily led to the phenomenon of the plush cloth absorbing water and swelling, uneven friction texture, and a pretilt angle deviation of ±0.45°. The process capability index CPK fluctuated between 0.8 and 1.1, resulting in poor quality stability. The yield rate of the friction process was only 92.1%, and the rework rate was 3.5%.

[0040] After the modification in this embodiment, the humidity fluctuation in the friction area is stably controlled within ±3% (47-53%RH) of the target humidity, and the humidity control response time is ≤3 minutes; the process capability index CPK is stabilized to above 1.4, eliminating abnormal friction texture defects caused by high humidity in summer, reducing abnormal wear of the plush fabric due to water absorption and expansion, and extending its service life by about 15%; the yield rate of the friction process is stabilized at above 96%, and customer complaints related to static electricity and humidity are reduced from 3-5 per month to 0-1.

[0041] The equipment cost is 280,000 yuan, the annual operating cost is 35,000 yuan, the annual revenue is about 1.5 million yuan, and the investment payback period is about 2.5 months. Example

[0042] This embodiment is based on the same humidifier circulation system as in Embodiment 1, applied to the same LCD production line under winter operating conditions. Its humidity control method is basically the same as in Embodiment 1, with the following differences: the target humidity is set to 55%RH, the alarm humidity threshold remains at 65%RH, the target temperature is maintained at 22℃, the PLC controller determines the humidification start threshold to be 95% of the target humidity (52.25%RH), and the dehumidification start threshold to be 105% of the target humidity (57.75%RH). Under winter operating conditions, the system normally operates primarily with high-power humidification, and the dehumidification module only intermittently starts when local humidity is excessively high. The optimal circulating air volume and plush fabric tension parameters matched by the orthogonal experiment remain unchanged; only the humidity optimization levels are adjusted to three groups of 52.25%, 55%, and 57.75% to adapt to the dry winter environment. The remaining closed-loop adjustment logic, triple electrostatic suppression control, safety interlock mechanism, and air purification process are consistent with Embodiment 1.

[0043] Before this embodiment was implemented, the humidity of the workshop environment in winter was 25-35%RH. In the dry environment, the static electricity accumulation during the friction process was serious. After friction, the electrostatic field strength on the substrate surface reached 3000-5000V / cm. Electrostatic adsorption of micron-sized dust caused pinholes and scratches. The pretilt angle deviation reached ±0.5°. The yield of the friction process was only 91%, and the rework rate reached 4.2%.

[0044] After modification in this embodiment, the surface potential of the substrate after friction decreased from 3000-5000V / cm to below 400V / cm, and the time for the surface potential to decay to below 500V / cm was 54 seconds; the number of particles ≥3μm decreased from 15-20 per piece to 3-5 per piece, a reduction of more than 70%; the pretilt angle deviation decreased from ±0.5° to ±0.25°, and the friction depth stabilized in the 20-50nm range; the yield of the friction process increased from 91% to 95.2%, an increase of 4.2 percentage points; the electrostatic defect rate decreased by about 70%, and the rework rate decreased significantly. Example

[0045] Based on Examples 1 and 2, this example further realizes intelligent humidity control: (1) Incorporate humidity control data into the SPC statistical process control system and establish a correlation model or correlation database between humidity and friction quality (quality indicators such as surface potential and pretilt angle); specifically, automatically upload data such as hourly average humidity, humidity fluctuation standard deviation, and humidification / dehumidification frequency to the SPC system, draw a humidity control process capability control chart, monitor Cpk value in real time, and conduct correlation analysis with the surface potential and pretilt angle detection results of the substrate after friction to continuously optimize control parameters.

[0046] (2) Adopting AI predictive control algorithm, based on historical data and environmental change trends, predicts humidity fluctuations and adjusts humidification or dehumidification power in advance, further improving control accuracy and response speed; Specifically, adopting AI prediction algorithm based on long short-term memory network (LSTM), using historical environmental temperature and humidity data of the past 7 days to predict the humidity change trend in the next 30 minutes, and pre-adjusting humidification or dehumidification power 10 minutes in advance, so that the humidity fluctuation range is further reduced to within ±2%RH and the response time is shortened to ≤2 minutes.

[0047] (3) It is linked with auxiliary static elimination equipment such as ion electrostatic bars to form a comprehensive static electricity protection system. Specifically, when the humidity control is normal but the surface potential is still too high, the PLC can send an enhanced ion output command to the ion electrostatic bar; conversely, when the humidity control has effectively reduced static electricity, the working voltage of the ion bar can be appropriately reduced to save energy and extend the electrode life, forming a comprehensive static electricity protection system of "humidity-led and electrostatic bar-assisted".

[0048] Experimental results show that after adopting AI predictive humidity control, the humidity fluctuation range is further reduced to within ±2%RH, the control response time is shortened to ≤2 minutes, and the yield of the friction process is further improved to over 96.5%.

[0049] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A humidifier circulation system for an LCD friction process, characterized in that, The system includes a humidifier circulation unit, an environmental monitoring unit, and a control unit. The humidifier circulation unit, located near the friction workshop, includes a pure water storage tank, a humidification module, a dehumidification module, a HEPA filter, and a circulating fan. One end of the humidification module is connected to the pure water storage tank pipeline, and the other end is connected to the HEPA filter inlet pipeline. The HEPA filter inlet is also connected to the dehumidification module via a pipeline. The HEPA filter outlet is connected to the circulating fan pipeline, and the circulating fan outlet is connected to several nozzles via a pipeline. The nozzles are fixedly installed above the friction machine in the friction workshop. The environmental monitoring unit includes multi-point temperature and humidity sensors distributed in the friction area of ​​the friction machine for real-time collection of environmental temperature and humidity data in the friction area. The control unit is connected to the humidification module, the dehumidification module, the circulating fan, and the temperature and humidity sensors. Based on the deviation between the temperature and humidity data collected by the temperature and humidity sensors and the preset target humidity, the control unit automatically adjusts the output power of the humidification module, the start / stop of the dehumidification module, and the speed of the circulating fan to control the environmental humidity in the friction area within the target humidity ±3%RH range, with a humidity control response time ≤3 minutes.

2. The humidifier circulation system for an LCD friction process according to claim 1, characterized in that, The pure water storage tank uses ultrapure water with a resistivity ≥18.25MΩ・cm as the humidification water source and is equipped with a UV disinfection device to prevent microbial growth. The humidification module uses an electrode humidifier with a humidification capacity ≥10kg / h and a humidity control accuracy of ±2%RH. The dehumidification module uses an industrial dehumidifier with a dehumidification capacity ≥20L / day. The HEPA filter has a filtration grade of H13 and a filtration efficiency ≥99.97%. The circulating fan uses a frequency converter-controlled fan with an air volume of 1000-1500m³ / h.

3. The humidifier circulation system for an LCD friction process according to claim 1, characterized in that, The nozzles are evenly distributed above the friction machine and face upwards, and the vertical distance between the nozzles and the friction machine is controlled within 0.3-0.5m.

4. The humidifier circulation system for an LCD friction process according to claim 1, characterized in that, The multi-point temperature and humidity sensors consist of 4-6 sets, distributed around the friction area. The accuracy of the temperature and humidity sensors is ±0.5%RH. The control unit is a PLC controller and is equipped with a human-machine interface.

5. The humidifier circulation system for an LCD friction process according to claim 4, characterized in that, The target humidity is set according to the season, with a target humidity of 55%RH in winter and 50%RH in summer.

6. The humidifier circulation system for an LCD friction process according to claim 1, characterized in that, It also includes a safety protection unit, which includes a humidity alarm device, a leakage protection device and an emergency drainage device. The humidity alarm device is equipped with an alarm humidity threshold, which is set to 65%RH.

7. A humidity control method for an LCD friction process, characterized in that, The LCD friction process humidifier circulation system as described in any one of claims 1-4 includes the following steps: S1. Parameter setting: The target humidity and target temperature of the friction environment are set according to the season through the PLC controller. The target humidity in summer is set to 50%RH, the target humidity in winter is set to 55%RH, the alarm humidity threshold is set to 65%RH, the safe humidity threshold is set to 60%RH, and the target temperature is set to 22℃. S2. Real-time monitoring: Real-time collection of ambient temperature and humidity data at multiple locations above, below, left, and right of the friction area using multi-point temperature and humidity sensors and transmission to the PLC controller. S3. Closed-loop regulation: The PLC controller calculates the deviation between the target humidity value and the measured humidity value. When the measured humidity is lower than 95% of the target humidity value, the output power of the humidifier and the speed of the circulating fan are increased. When the measured humidity is higher than 105% of the target humidity value, the dehumidifier is started and the power of the humidifier is reduced. The humidity control keeps the humidity fluctuation range in the friction area within ±3%RH of the target humidity. The humidity control response time is ≤3 minutes. S4. Optimization of process parameters: An orthogonal experiment on humidity-friction quality was conducted with four factors and three levels: target humidity, humidity fluctuation range, circulating air volume, and plush fabric tension. The optimal parameter combination was determined, and the pretilt angle deviation was controlled within ±0.3° and the friction depth was controlled within 20-50nm. A humidity-surface potential-pretilt angle correlation database was established to achieve traceability of process parameters. S5, Safety Interlock: (1) When the measured humidity exceeds the alarm humidity threshold, the emergency dehumidification program is triggered and an alarm signal is issued. If the measured humidity does not drop below the safe humidity threshold within the specified time, the shutdown command is executed. (2) Set a high humidity exposure timer to record the cumulative time when the measured humidity exceeds the safe humidity threshold for a single consecutive time. If the time exceeds 4 hours, even if the alarm humidity threshold is not reached, the system will still be judged as an abnormal working condition and will trigger the emergency dehumidification program and issue an alarm signal. If the measured humidity does not drop below the safe humidity threshold within the specified time, the shutdown command will be executed. (3) Simultaneously perform leakage current detection and grounding status monitoring to ensure electrical safety; S6. Air purification: The circulating air is filtered through an H13 grade HEPA filter throughout the entire process, and the humidification water source uses ultrapure water with a resistivity ≥18.25MΩ·cm and is regularly disinfected with UV.

8. The humidity control method for the LCD friction process according to claim 7, characterized in that, In step S3, triple electrostatic suppression is achieved through humidity control: (1) Improved surface conductivity: Moisture adsorbed on the surface of the PI layer forms a conductive path, promotes charge leakage, and makes the time for the surface potential to decay to within 500V / cm ≤60 seconds. (2) Enhanced air ionization: Increased humidity increases the degree of air ionization and accelerates charge neutralization; (3) Dust suppression: Increase ambient humidity to reduce dust flying and electrostatic adsorption, and control the number of ≥3μm particles to ≤5 per piece.

9. The humidity control method for the LCD friction process according to claim 7, characterized in that, It also includes intelligent expansion steps: (1) Incorporate humidity control data into the SPC statistical process control system and establish a correlation model between humidity and friction quality; (2) Adopt AI predictive control algorithm to predict humidity fluctuations based on historical data and environmental change trends, and adjust the humidification or dehumidification power in advance; (3) It is linked with auxiliary static removal equipment such as ion static bar to form a comprehensive static protection system.

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