Large-size panel film forming consistency optimization method for ink-jet printing

Abstract

The invention belongs to the related technical field of ink-jet printing decompression film forming, and particularly relates to a large-size panel film forming consistency optimization method for ink-jet printing, which comprises the following steps of: in a liquid drop evaporation film forming process, adopting three groups of observation components, film forming images of the center, the edge and the corner area of the printing substrate located in the cavity are observed above the large-size reduced pressure evaporation cavity; processing the film forming image of each region, and extracting the current droplet volume of a single pixel pit of each region; determining a difference value between a preset current reference volume and a current droplet volume of a single pixel pit in each region, and determining a target temperature of the corresponding region in combination with a relational expression based on the temperature and the evaporation speed; based on the difference between the target temperature and the actual temperature, the temperature of the area is controlled through a temperature controller of the corresponding area; and the steps are circulated until the liquid drops on the printing substrate are completely formed into the film or the process time is over. According to the invention, the consistency of reduced pressure evaporation film formation can be realized on line.

Description

Technical Field

[0001] The present invention belongs to the technical field related to decompression film formation in inkjet printing, and more specifically, relates to a method for optimizing the consistency of film formation on large-size panels used for inkjet printing. Background Art

[0002] As an additive manufacturing process, inkjet printing is regarded as a key link in new display technology due to its high material utilization rate, simplified process flow and suitability for large-size flexible production. At present, many panel manufacturers have invested in the research and development of inkjet printing equipment and have carried out a series of OLED printing production experiments. However, in the initial exploration stage of the process route, there are still some problems that need to be solved. For example, in the evaporation film forming process of large-size panels, due to the differences in the air flow field and vapor concentration, the evaporation rate of droplets in each area is uneven, resulting in poor consistency in the final film morphology. Insufficient film formation consistency will not only affect the display effect of large-size panels, but also have a negative impact on key performance indicators such as their lifespan. Therefore, the evaporation process of large-size panels in the reduced pressure evaporation system must be monitored in real time and actively adjusted to optimize the final film formation consistency.

[0003] In order to solve the above problems, the existing vacuum evaporation system adds a circle of solution around to balance the evaporation rate of each area. However, most systems lack the ability to monitor the evaporation process of large-size panels in real time, and cannot timely perceive local anomalies in the film formation process. It is difficult to quickly adjust the process parameters to maintain the consistency of the film layer. When facing different materials or substrate sizes, the adaptability is poor, and the versatility and robustness of the process are insufficient. Therefore, it is necessary to optimize the design of the vacuum evaporation system, improve the functional design of the vacuum evaporation system, and propose a film formation consistency optimization method with active monitoring and real-time adjustment. Summary of the invention

[0004] In response to the above defects or improvement needs of the prior art, the present invention provides a method for optimizing the film formation consistency of large-size panels for inkjet printing, which aims to solve the technical problem of poor film formation consistency in different areas due to the inability to detect abnormalities in the evaporation and curing process in real time in the existing reduced pressure evaporation film formation.

[0005] To achieve the above object, according to one aspect of the present invention, a method for optimizing the film formation consistency of a large-size panel for inkjet printing is provided, comprising:

[0006] S1. During the droplet evaporation film forming process, three sets of observation components are used to observe the film forming images of the center, edge and corner areas of the printed substrate located in the cavity above the large-size reduced pressure evaporation cavity; the film forming images of each area are processed to extract the current droplet volume of a single pixel pit in each area;

[0007] S2. Determine the difference between the preset current reference volume and the current droplet volume of a single pixel pit in each area, and determine the target temperature of the corresponding area based on the relationship between temperature and evaporation rate, combined with the difference and the actual pressure in the cavity collected; based on the difference between the determined target temperature of each area and the actual temperature of the corresponding area collected by the sensor, control the temperature of the area through the temperature controller of the corresponding area, so that the overall evaporation rate of the droplets in each area is consistent;

[0008] S3. During the evaporation process, steps S1-S2 are repeated until the droplets on the printed substrate are completely film-formed or the process time is completed.

[0009] Furthermore, in S1, the current droplet volume of a single pixel pit in each region is calculated as follows:

[0010]

[0011] Where V is the current volume of a single droplet, R is the measured real-time contact radius of a single droplet, and θ is the measured real-time contact angle of a single droplet.

[0012] Further, in S2, the current droplet volume of a single pixel pit in the central area is taken as the preset current reference volume, and based on the relationship between temperature and evaporation rate, the target temperatures of the edge area and the corner area are determined by the following formulas:

[0013]

[0014] Where Δt represents the time interval for temperature adjustment, V c Represents the current droplet volume of a single pixel pit in the middle area, V e Represents the current droplet volume of a single pixel pit in the edge area, V m represents the current droplet volume of a single pixel pit in the corner area; T e represents the substrate temperature of the edge region to be determined; T m represents the substrate temperature of the corner area to be determined; T C Indicates the current substrate temperature in the middle area; P ∞,e , P ∞,m , P ∞，c They represent the air pressure in the edge area, corner area, and middle area determined by actual measurement, respectively; M represents the molecular weight of the droplet, ρ represents the density of the droplet, R represents the ideal gas constant, and P v (T) represents the saturated vapor pressure of the droplet at temperature T; D represents the diffusion coefficient of the droplet; A represents the surface area of ​​the droplet.

[0015] Further, in S2, a specific target value is preset as the current reference volume, and based on the relationship between temperature and evaporation rate, the target temperatures of the center area, edge area and corner area are determined by the following formulas:

[0016]

[0017] Where V represents the current reference volume; V c Represents the current droplet volume of a single pixel pit in the middle area, V e Represents the current droplet volume of a single pixel pit in the edge area, V m represents the current droplet volume of a single pixel pit in the corner area; M represents the molecular weight of the droplet, ρ represents the density of the droplet, R represents the ideal gas constant, P v (T) represents the saturated vapor pressure of the droplet at temperature T; D represents the diffusion coefficient of the droplet; A represents the surface area of ​​the droplet; T e represents the substrate temperature of the edge region to be determined; T m represents the substrate temperature of the corner area to be determined; T C represents the current substrate temperature in the middle area; Δt represents the time interval for temperature adjustment; P ∞，e , P ∞，m , P ∞，c They respectively represent the air pressure in the edge area, corner area, and middle area determined by actual measurement.

[0018] According to another aspect of the present invention, there is provided a large-size reduced pressure evaporation system for inkjet printing, comprising: a large-size reduced pressure evaporation chamber, a pressure control component, three sets of observation components, a controller, and a temperature control component;

[0019] Among them, the large-sized reduced pressure evaporation chamber is used as a large-sized panel film forming space area; the pressure control component is used to make the large-sized reduced pressure evaporation chamber temporarily pressurized and back-pressurized at any vacuum degree; the three groups of observation components are respectively arranged outside the large-sized reduced pressure evaporation chamber and located directly above the center, edge and corner areas of the printed substrate in the chamber, and are used to observe the film forming images of the center, edge and corner areas of the printed substrate located in the chamber through the observation windows on the chamber above the large-sized reduced pressure evaporation chamber during the droplet evaporation film forming process; the temperature control component is used to collect the actual temperature of the substrate in each area;

[0020] The controller is used to execute the following steps in the above-mentioned large-size panel film formation consistency optimization method: processing the film formation image of each area, extracting the current droplet volume of a single pixel pit in each area, determining the difference between the preset current reference volume and the current droplet volume of a single pixel pit in each area, and based on the relationship between temperature and evaporation rate, combining the difference and the actual pressure in the cavity, determining the target temperature of the corresponding area; based on the difference between the determined target temperature of each area and the collected actual temperature, determining the modulation temperature of the corresponding area;

[0021] The temperature control component is further used to control the temperature of each region based on the modulation temperature so that the overall evaporation rate of the droplets in each region is consistent.

[0022] Furthermore, the temperature control component includes three temperature controllers and corresponding temperature sensors and water bath heating pipelines; each temperature controller is used to adjust the substrate temperature of the corresponding area.

[0023] Furthermore, each set of observation components includes an observation camera, a coaxial light source and a lens; and is used to be continuously triggered by a controller to ensure that the camera and the light source work together to collect film-forming images of the corresponding area in real time.

[0024] In general, compared with the prior art, the technical solution conceived by the present invention has the following beneficial effects:

[0025] 1. The present invention proposes a method for optimizing the consistency of film formation on large-size panels for inkjet printing, which obtains the droplet image information of the center, edge and corner areas based on the visual observation component, and then calculates the current droplet volume of a single pixel pit in each area. By comparing the volume differences of each area, that is, determining the difference between the preset current reference volume and the current droplet volume of a single pixel pit in each area, and based on the relationship between temperature and evaporation rate, combining the above difference to determine the target temperature of the corresponding area, and adjusting the regional temperature in the next time interval, the evaporation process of large-scale droplets can be synchronized, thereby achieving a highly consistent film formation result. Therefore, the present invention can solve the technical problem of poor film formation consistency in different areas due to the inability to detect abnormalities in the evaporation and curing process in real time in the existing reduced pressure evaporation film formation.

[0026] 2. The present invention further proposes that the current droplet volume of a single pixel pit in any area can be selected as the reference volume, and the evaporation rates of the other two areas can be adjusted to make the droplet volume of the entire panel consistent. Since the evaporation rate of the central area is usually more reasonable and accurate, the current droplet volume of a single pixel pit in the central area is preferably used as the reference to determine the control temperature of the edge and corner areas, so as to efficiently achieve film formation consistency.

[0027] 3. The present invention further proposes to preset a volume as a reference volume, which can more flexibly meet actual generation needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a flowchart of a method for optimizing the film formation consistency of a large-size panel for inkjet printing provided by an embodiment of the present invention;

[0029] Figure 2 Schematic diagram of a large-scale reduced pressure evaporation system for inkjet printing provided by an embodiment of the present invention;

[0030] Figure 3 is a schematic structural diagram of a carrier for inkjet printing provided by an embodiment of the present invention;

[0031] Figure 4 Schematic diagram of a droplet volume observation and measurement method for inkjet printing provided by an embodiment of the present invention;

[0032] Figure 5 It is a schematic diagram of information flow of a consistency optimization method for inkjet printing provided by an embodiment of the present invention;

[0033] Figure 6 is a composition diagram of a control system for inkjet printing provided by an embodiment of the present invention;

[0034] Figure 7 It is a flow chart of a method for optimizing film formation consistency for inkjet printing provided in an embodiment of the present invention.

[0035] Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0036] 11 is a cavity, 12 is an observation window, 13 is a carrier, 21, 22, 23 are three temperature controllers; 24, 25, 26 are three water bath pipelines, 27, 28, 29 are three humidity sensors, 210, 211, 212 are three temperature sensors, 31, 32, 33 are three sets of observation components, 311 is an observation camera, 312 is a lens, 313 is a coaxial light source, 41 is a vacuum pump, 42, 43 are two vacuum solenoid valves, 44 is a pressure gauge, 45 is an air supply source, 51 is a controller, DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0038] Embodiment 1

[0039] A method for optimizing the film formation consistency of large-size panels for inkjet printing, such as Figure 1 As shown, including:

[0040] S1. During the droplet evaporation film forming process, three sets of observation components are used to observe the film forming images of the center, edge and corner areas of the printed substrate located in the cavity above the large-size reduced pressure evaporation cavity; the film forming images of each area are processed to extract the current droplet volume of a single pixel pit in each area;

[0041] S2. Determine the difference between the preset current reference volume and the current droplet volume of a single pixel pit in each area, and determine the target temperature of the corresponding area based on the relationship between temperature and evaporation rate, combined with the difference and the actual pressure in the cavity collected; based on the difference between the determined target temperature of each area and the actual temperature of the corresponding area collected by the sensor, control the temperature of the area through the temperature controller of the corresponding area, so that the overall evaporation rate of the droplets in each area is consistent;

[0042] S3. During the evaporation process, steps S1-S2 are repeated until the droplets on the printed substrate are completely film-formed or the process time is completed.

[0043] Based on the film formation image, real-time parameters such as droplet diameter, volume and evaporation rate can be obtained through image processing algorithms and feature extraction technology. The temperature distribution in the center, edge and corner areas of the substrate can be independently controlled by three temperature controllers.

[0044] This embodiment proposes a film formation consistency optimization method based on a reduced pressure evaporation system, obtains the droplet image information of each area according to the visual observation component, and then calculates the droplet volume of each area. By comparing the volume difference of each area, adjusting the regional temperature in the next time interval based on the relationship between temperature and evaporation rate, the evaporation process of large-scale droplets can be synchronized, thereby achieving a highly consistent film formation result.

[0045] As a preferred implementation, in S1, the current droplet volume of a single pixel pit in each area is calculated as follows:

[0046]

[0047] Where V is the current volume of a single droplet, R is the measured real-time contact radius of a single droplet, and θ is the measured real-time contact angle of a single droplet.

[0048] Regarding the relationship between temperature and evaporation rate, the evaporation rate of droplets in each area It is expressed as:

[0049]

[0050] Where t is the evaporation time, D is the diffusion coefficient of the droplet, which is related to the specific type of droplet, M is the molecular weight of the droplet, ρ is the density of the droplet, R is the ideal gas constant, T is the droplet temperature, and P v (T) is the saturated vapor pressure of the droplet at temperature T, C ∞ is the vapor partial pressure in the cavity, and A is the surface area of ​​the droplet. v (T) Specifically: Where L is the latent heat of vaporization of the droplet, and C is an integral constant that is uniformly specific to the droplet. ∞ The temperature T and temperature T can be detected by temperature sensors and humidity sensors in different areas of the reduced pressure evaporation system.

[0051] During the temperature adjustment process, the real-time volume V of the droplet of a single pixel pit in the three regions is calculated. c 、V e and V m , determine the temperature T of each area in the next time interval c , T e and T m The droplet volume of any area can be selected as the reference volume, and the evaporation rate of the other two areas can be adjusted to make the droplet volume of the entire panel consistent. The droplet volume of the center area is preferably selected as the reference. By adjusting the temperature of the edges and corners of the large-size substrate, the real-time droplet volume of the three areas is consistent.

[0052] Therefore, as a preferred implementation, in S2, the current droplet volume of a single pixel pit in the central area is used as the preset current reference volume, and based on the relationship between temperature and evaporation rate, the target temperatures of the edge area and the corner area are determined by the following formulas:

[0053]

[0054] Where Δt represents the time interval for temperature adjustment, V c Represents the current droplet volume of a single pixel pit in the middle area, V e Represents the current droplet volume of a single pixel pit in the edge area, V m represents the current droplet volume of a single pixel pit in the corner area; T e represents the substrate temperature of the edge region to be determined; T m represents the substrate temperature of the corner area to be determined; T C Indicates the current substrate temperature in the middle area; P ∞,e , P ∞,m , P ∞,cThey represent the air pressure in the edge area, corner area, and middle area determined by actual measurement, respectively; M represents the molecular weight of the droplet, ρ represents the density of the droplet, R represents the ideal gas constant, and P v (T) represents the saturated vapor pressure of the droplet at temperature T; D represents the diffusion coefficient of the droplet; A represents the surface area of ​​the droplet.

[0055] As another preferred implementation, in S2, a specific target value is preset as the current reference volume, and based on the relationship between temperature and evaporation rate, the target temperatures of the center area, edge area and corner area are respectively determined by the following formulas:

[0056]

[0057] Where V represents the current reference volume; V c Represents the current droplet volume of a single pixel pit in the middle area, V e Represents the current droplet volume of a single pixel pit in the edge area, V m represents the current droplet volume of a single pixel pit in the corner area; M represents the molecular weight of the droplet, ρ represents the density of the droplet, R represents the ideal gas constant, P v (T) represents the saturated vapor pressure of the droplet at temperature T; D represents the diffusion coefficient of the droplet; A represents the surface area of ​​the droplet; T e represents the substrate temperature of the edge region to be determined; T m represents the substrate temperature of the corner area to be determined; T C represents the current substrate temperature in the middle area; Δt represents the time interval for temperature adjustment; P ∞,e , P ∞，m , P ∞，c They respectively represent the air pressure in the edge area, corner area, and middle area determined by actual measurement.

[0058] Embodiment 2

[0059] A large-size decompression evaporation system for inkjet printing, comprising: a large-size decompression evaporation chamber, a pressure control component, three groups of observation components, a controller, and a temperature control component;

[0060] Among them, the large-size vacuum evaporation chamber, as the film-forming space area of ​​the large-size panel, includes a chamber and a carrier, and is the main place for evaporation film formation of the printed substrate; the pressure control component is used to make the large-size vacuum evaporation chamber temporarily pressurized and back-pressurized at any vacuum degree; three groups of observation components are respectively arranged outside the large-size vacuum evaporation chamber and located directly above the center, edge and corner areas of the printed substrate in the chamber, and are used to observe the film-forming images of the center, edge and corner areas of the printed substrate located in the chamber through the observation windows on the chamber above the large-size vacuum evaporation chamber during the droplet evaporation film-forming process; the temperature control component is used to collect the actual temperature of the substrate in each area;

[0061] The controller is used to execute the following steps in the above-mentioned large-size panel film formation consistency optimization method: processing the film formation image of each area, extracting the current droplet volume of a single pixel pit in each area, determining the difference between the preset current reference volume and the current droplet volume of a single pixel pit in each area, and based on the relationship between temperature and evaporation rate, combining the above difference and the actual pressure in the cavity, determining the target temperature of the corresponding area; based on the difference between the determined target temperature of each area and the collected actual temperature, determining the modulation temperature of the corresponding area;

[0062] The temperature control component is also used to control the temperature of each area based on the modulation temperature so that the overall evaporation rate of the droplets in each area is consistent.

[0063] Different from the existing vacuum evaporation system, after the printed substrate is placed in the cavity for drying, it is impossible to understand the evaporation state and process of the droplets inside, and the film formation result is uncontrollable. This embodiment is equipped with multiple sets of visual observation systems, which can monitor the evaporation state of droplets in different areas in real time during the vacuum cavity drying process.

[0064] The pressure control component may include a vacuum pump, an exhaust pipeline, a vacuum solenoid valve, an air supply source, and a pressure gauge, which can temporarily pressurize and back-pressurize the cavity at any vacuum degree. In addition, in general, the controller is used to receive real-time information collected by the vacuum evaporation system and process and send control signals; the observation component is installed on the top of the cavity, and the cavity below the observation component is equipped with an observation window, which can ensure that the observation component collects a clear droplet image; the temperature control component is connected to the carrier in the cavity and controls the temperature distribution of the carrier.

[0065] As a preferred implementation, the temperature control component includes three temperature controllers and corresponding temperature sensors and a water bath heating pipeline; each temperature controller is used to adjust the substrate temperature of a corresponding area.

[0066] By installing temperature sensors in the vacuum evaporation system, the evaporation rate of droplets in each area can be calculated in real time. In addition, the evaporation rate of droplets in each area can be regulated by controlling the temperature zones at the edge, corner and center.

[0067] As a preferred implementation, each set of observation components includes an observation camera, a coaxial light source and a lens; which are used to be continuously triggered by a controller to ensure that the camera and the light source work together to collect the film-forming image of the corresponding area in real time.

[0068] Based on the film formation image, the controller obtains real-time parameters such as droplet diameter, volume and evaporation rate through image processing algorithms and feature extraction technology. A set is installed at the center, edge and corner of the printed substrate to monitor the evaporation status of different substrate areas.

[0069] Figure 2 The schematic diagram of the structure of the reduced pressure evaporation system for inkjet printing is shown in Figure 1. The system mainly includes a large-sized reduced pressure evaporation chamber, a pressure control component, an observation component, a temperature control component and a controller. Figure 3 and Figure 4 They are respectively a schematic diagram of the structure of the carrier used for inkjet printing and a schematic diagram of the droplet volume observation and measurement method. The following will explain them one by one in detail.

[0070] like Figure 2 As shown, the large-size vacuum evaporation chamber includes a chamber 11, an observation window 12 and a support platform 13. The chamber 11 is a closed space that forms a vacuum environment, and the ink droplets on the substrate after inkjet printing are decompressed and evaporated to obtain a uniform film morphology. The observation window 12 installed above the chamber ensures that the observation camera can normally obtain the droplet evaporation image. The support platform 13 supports the printed substrate to support it in the chamber and transfer heat.

[0071] The temperature control components include thermostats 21, 22, 23 and water bath pipes 24, 25, 26, as well as humidity sensors 27, 28, 29 and temperature sensors 210, 211, 212. The three thermostats control the temperature of the middle, edge and corner areas respectively, and can adjust the temperature of the transmitted medium. The water bath pipe is the carrier of the medium, which is connected to the pipe interface inside the carrier. The temperature sensor and humidity sensor respectively monitor the temperature and vapor pressure information of each area when the droplet evaporates.

[0072] The observation component includes three observation devices 31, 32, 33, wherein the observation component is composed of an observation camera 311, a lens 312, and a coaxial light source 313. The observation component is installed above the observation window to collect the evaporation process of the droplets in each area in real time.

[0073] The pressure control component includes a vacuum pump 41, vacuum solenoid valves 42, 43, a pressure gauge 44 and an air supply source 45. The vacuum pump can reduce the pressure of the cavity and evacuate it. The vacuum solenoid valve controls the opening and closing of the exhaust pipeline to achieve stable pressure reduction. The pressure gauge monitors the pressure in the cavity in real time to prevent the pressure from overshooting or failing to reach the specified pressure. The air supply source replenishes the cavity with air after the drying process to restore it to the atmospheric pressure state.

[0074] The controller 51 is used to collect and process the information collected by various sensors, and can obtain the droplet image information and environmental information of each area during evaporation, so as to determine whether to adjust the temperature. In addition, the controller is also responsible for sending various instructions to the vacuum pump, solenoid valve, thermostat, etc. to realize pressure control and temperature control.

[0075] like Figure 3 As shown in the figure, the temperature control component can realize temperature zoning control on the carrier. The water bath pipeline is divided into three lines, which are laid in the center, edge and corner area of ​​the carrier respectively. By zoning the pipeline, the temperature can be adjusted when the evaporation speed of droplets in different areas is different.

[0076] like Figure 4 As shown, the observation component uses a camera 311 as a sensor for collecting image information, collects image information of the droplet through a lens 312 and a coaxial light source 313, and transmits the image information to the controller for processing to obtain the real-time radius and contact angle of the droplet.

[0077] like Figure 5 and Figure 6 The following are information flow diagrams of the consistency optimization method and control system composition diagrams of this embodiment. The temperature of each area can be obtained in real time through temperature sensors 210, 211 and 212; the vapor pressure of each area can be obtained in real time through humidity sensors 27, 28 and 29. The controller 51 collects the droplet environment information of each area and calculates the evaporation rate of the area.

[0078] After obtaining the real-time volume and evaporation rate of the droplets in each area, the temperature of the substrate in each area is controlled according to the preset reference volume in view of the possible inconsistency of evaporation rate and process in each area.

[0079] For example, Figure 7 A method for inkjet printing reduced pressure evaporation is shown, comprising the following steps:

[0080] (1) Setting the initial temperature of the carrier 13, and raising the temperature of the carrier 13 through the water bath pipeline by the temperature controllers 21, 22, and 23;

[0081] (2) After the printed panel is transferred into the vacuum system, the pressure in the cavity is pumped to a specified vacuum degree through the pressure control component, so that the droplets on the printed panel evaporate to form a film;

[0082] (3) The controller 51 calculates the current droplet volume of a single pixel pit in different regions based on the acquisition of the film formation image, and calculates the droplet evaporation rate in each region;

[0083] (4) Calculating the adjusted platform temperature of each area, and sending instructions from the controller 51 to the corresponding temperature controllers 21, 22, 23 for adjustment;

[0084] (5) cyclically performing steps (3) to (4) until the film is completely formed or the process time is reached;

[0085] (6) The controller 51 sends a command to the air supply source 45 to replenish the air in the cavity and return the pressure to atmospheric pressure, and then take out the dried panel.

[0086] The relevant technical solution is the same as that in Embodiment 1 and will not be described in detail here.

[0087] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for optimizing the film formation consistency of large-size panels for inkjet printing, characterized in that: include: S1. During the droplet evaporation film forming process, three sets of observation components are used to observe the film forming images of the center, edge and corner areas of the printed substrate located in the cavity above the large-size reduced pressure evaporation cavity; the film forming images of each area are processed to extract the current droplet volume of a single pixel pit in each area; S2, determining the difference between the preset current reference volume and the current droplet volume of a single pixel pit in each area, and determining the target temperature of the corresponding area based on the relationship between temperature and evaporation rate, combined with the difference and the collected actual pressure in the cavity; Based on the difference between the determined target temperature of each area and the actual temperature of the corresponding area collected by the sensor, the temperature of the area is controlled by the temperature controller of the corresponding area so that the overall evaporation rate of the droplets in each area is consistent; S3. During the evaporation process, steps S1-S2 are repeated until the droplets on the printed substrate are completely film-formed or the process time is completed.

2. The method for optimizing film formation consistency of large-size panels according to claim 1, characterized in that: In S1, the current droplet volume of a single pixel pit in each area is calculated as follows: Where V is the current volume of a single droplet, R is the measured real-time contact radius of a single droplet, and θ is the measured real-time contact angle of a single droplet.

3. The method for optimizing the film formation consistency of a large-size panel according to claim 1, characterized in that: In S2, the current droplet volume of a single pixel pit in the central area is taken as the preset current reference volume. Based on the relationship between temperature and evaporation rate, the target temperatures of the edge area and the corner area are determined by the following formulas: Where Δt represents the time interval for temperature adjustment, V c Represents the current droplet volume of a single pixel pit in the middle area, V e Represents the current droplet volume of a single pixel pit in the edge area, V m represents the current droplet volume of a single pixel pit in the corner area; T e represents the substrate temperature of the edge region to be determined; T m represents the substrate temperature of the corner region to be determined; T C Indicates the current substrate temperature in the middle area; P ∞，e , P ∞，m , P ∞，c They represent the air pressure in the edge area, corner area, and middle area determined by actual measurement, respectively; M represents the molecular weight of the droplet, ρ represents the density of the droplet, R represents the ideal gas constant, P v (T) represents the saturated vapor pressure of the droplet at temperature T; D represents the diffusion coefficient of the droplet; A represents the surface area of ​​the droplet.

4. The method for optimizing film formation consistency of large-size panels according to claim 1, characterized in that: In S2, a specific target value is preset as the current reference volume. Based on the relationship between temperature and evaporation rate, the target temperatures of the center area, edge area and corner area are determined by the following formulas: Where V represents the current reference volume; V c Represents the current droplet volume of a single pixel pit in the middle area, V e Represents the current droplet volume of a single pixel pit in the edge area, V m represents the current droplet volume of a single pixel pit in the corner area; M represents the molecular weight of the droplet, ρ represents the density of the droplet, R represents the ideal gas constant, P v (T) represents the saturated vapor pressure of the droplet at temperature T; D represents the diffusion coefficient of the droplet; A represents the surface area of ​​the droplet; T e represents the substrate temperature of the edge region to be determined; T m represents the substrate temperature of the corner area to be determined; T c represents the current substrate temperature in the middle area; Δt represents the time interval for temperature adjustment; P ∞，e , P ∞，m , P ∞，c They respectively represent the air pressure in the edge area, corner area, and middle area determined by actual measurement.

5. A large-scale vacuum evaporation system for inkjet printing, characterized in that: include: Large-sized decompression evaporation chamber, pressure control components, three sets of observation components, controllers, and temperature control components; Among them, the large-sized reduced pressure evaporation chamber is used as a large-sized panel film forming space area; the pressure control component is used to make the large-sized reduced pressure evaporation chamber temporarily pressurized and back-pressurized at any vacuum degree; the three groups of observation components are respectively arranged outside the large-sized reduced pressure evaporation chamber and located directly above the center, edge and corner areas of the printed substrate in the chamber, and are used to observe the film forming images of the center, edge and corner areas of the printed substrate located in the chamber through the observation windows on the chamber above the large-sized reduced pressure evaporation chamber during the droplet evaporation film forming process; the temperature control component is used to collect the actual temperature of the substrate in each area; The controller is used to execute the following steps in the large-size panel film formation consistency optimization method as described in any one of claims 1 to 4: processing the film formation image of each area, extracting the current droplet volume of a single pixel pit in each area, determining the difference between the preset current reference volume and the current droplet volume of a single pixel pit in each area, and based on the relationship between temperature and evaporation rate, combining the difference and the actual pressure in the cavity, determining the target temperature of the corresponding area; based on the difference between the determined target temperature of each area and the collected actual temperature, determining the modulation temperature of the corresponding area; The temperature control component is further used to control the temperature of each region based on the modulation temperature so that the overall evaporation rate of the droplets in each region is consistent.

6. The large-scale vacuum evaporation system according to claim 5, characterized in that: The temperature control component includes three temperature controllers and corresponding temperature sensors and water bath heating pipelines; each temperature controller is used to adjust the substrate temperature of the corresponding area.

7. The large-scale vacuum evaporation system according to claim 5, characterized in that: Each set of observation components includes an observation camera, a coaxial light source and a lens; they are used to be continuously triggered by a controller to ensure that the camera and the light source work together to collect the film-forming image of the corresponding area in real time.

Images