Compensation method for film thickness uniformity in OLED inkjet printing

Abstract

The present application relates to the technical field of OLED, and in particular to a method for compensating for thickness uniformity in OLED inkjet printing, which includes: obtaining a target thickness of the OLED, mesh parameters of pixel grooves, and parameters related to ink droplets of each inkjet head in an inkjet device; calculating an inkjet volume and distribution of ink droplets in each pixel groove based on the target thickness, mesh parameters, and parameters related to ink droplets; inkjetting each pixel groove based on the inkjet volume and distribution in each pixel groove; baking each pixel groove to obtain a thickness of each mesh in each baked pixel groove; determining a compensation inkjet volume of each mesh in each pixel groove based on the thickness of each mesh in each pixel groove and the target thickness; and inkjetting each mesh in each pixel groove according to the compensation inkjet volume until the thickness of each pixel groove reaches the target thickness. Using this method, the thickness uniformity of the OLED can be improved.

Description

Related Applications

[0001] This application claims priority to a Chinese patent application filed with the State Intellectual Property Office of the People's Republic of China on February 6, 2023, bearing application number 202310064695.9 and entitled "Method for Compensating Film Thickness Uniformity in OLED Inkjet Printing," and a Chinese patent application filed with the State Intellectual Property Office of the People's Republic of China on November 2, 2022, bearing application number 202211364103.7 and entitled "Ink Droplet Printing Method, Apparatus, System and Storage Medium," the entire contents of which are incorporated herein by reference. [Technical Field]

[0002] This application relates to the field of OLED technology, and in particular to a method for compensating for film thickness uniformity in OLED inkjet printing. [Background technology]

[0003] OLED, a current-type light-emitting device, is increasingly being applied to high-performance displays. Due to its self-luminous properties, AMOLED has many advantages over LCD, such as high contrast ratio, ultra-thinness, and flexibility.

[0004] The OLED printing process uses an inkjet device to print OLED material and solvent ink into the pixel grooves of the TFT substrate using an inkjet head, forming a solution. Then, through VCD (vacuum drying) and bake processes, the solvent in the ink is volatilized and removed, leaving the OLED material to form a film in the pixel grooves. The volume and distribution of the ink droplets sprayed into the pixel grooves by the inkjet device directly affect the film thickness uniformity and film formation effect, which in turn affect the quality of light emission. Summary of the Invention [Problem to be solved by the invention]

[0005] In order to solve the problem of non-uniform film thickness in pixel grooves caused by OLED inkjet printing, conventional techniques have mainly improved the printing process flow, such as inkjet process, drying and baking, etc. However, it is difficult to precisely control the drying process at the pixel level, which is likely to cause non-uniform film thickness in pixel grooves. [Means for solving the problem]

[0006] According to embodiments of the present application, a method for compensating for film thickness uniformity in OLED inkjet printing is provided.

[0007] In a first aspect, the present application provides a method for compensating for film thickness uniformity in OLED inkjet printing, the method comprising: Obtaining a target film thickness of the OLED, a mesh parameter of a pixel groove, and parameters related to ink droplets of each inkjet head in an inkjet device, and calculating an inkjet volume and distribution of ink droplets in each pixel groove according to the target film thickness, the mesh parameter, and the parameters related to ink droplets; performing ink jetting on each pixel groove based on the ink jet volume and distribution status within each pixel groove; performing a baking process on each pixel groove and acquiring the film thickness of each mesh in each baked pixel groove; determining a compensation inkjet volume for each mesh in each pixel groove based on the film thickness of each mesh in each pixel groove and the target film thickness, and inkjetting each mesh in each pixel groove according to the compensation inkjet volume until the film thickness of each pixel groove reaches the target film thickness.

[0008] In a second aspect, the present application further provides an apparatus for compensating for film thickness uniformity in OLED inkjet printing, the apparatus comprising: an acquisition module for acquiring a target film thickness of the OLED, a mesh parameter of a pixel groove, and parameters related to ink droplets of each inkjet head in an inkjet device, and calculating an inkjet volume and distribution of ink droplets in each pixel groove according to the target film thickness, the mesh parameter, and the parameters related to ink droplets; an inkjet module for inkjet printing to each pixel groove based on the inkjet volume and distribution in each pixel groove; a film thickness acquisition module for performing a baking process on each pixel groove and acquiring the film thickness of each mesh in each baked pixel groove; and a refill module for determining a compensation inkjet volume for each mesh in each pixel groove based on the film thickness of each mesh in each pixel groove and the target film thickness, and for inkjetting each mesh in each pixel groove according to the compensation inkjet volume until the film thickness of each pixel groove reaches the target film thickness.

[0009] In a third aspect, the present application further provides a computer device including a memory and a processor, wherein a computer program is stored in the memory, and when executed by the processor, the computer program performs the steps of the method for compensating for film thickness uniformity in OLED inkjet printing according to the first aspect.

[0010] In a fourth aspect, the present application further provides a computer-readable storage medium having a computer program stored therein, the computer program being configured to perform the steps of the method for compensating for film thickness uniformity in OLED inkjet printing according to the first aspect when executed by a processor.

[0011] In a fifth aspect, the present application further provides a computer program product, the computer program product including a computer program that, when executed by a processor, performs the steps of the method for compensating for film thickness uniformity in OLED inkjet printing according to the first aspect.

[0012] The details of one or more embodiments of the application are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the application will become apparent from the description and drawings, and from the claims. [Brief explanation of the drawings]

[0013] To more clearly describe and explain the embodiments and / or examples of the invention disclosed herein, reference may be made to one or more drawings. Any description or illustration added to illustrate the drawings should not be construed as limiting the scope of either the disclosed invention, the described embodiments and / or examples, or the best mode of the invention as understood. [Figure 1] 1 is a schematic diagram illustrating an application environment of a method for compensating for film thickness uniformity in OLED inkjet printing in one embodiment; [Figure 2] 1 is a schematic flow chart of a method for compensating for film thickness uniformity in OLED inkjet printing in one embodiment. [Figure 3] FIG. 10 is a schematic diagram illustrating pixel groove meshing in an embodiment. [Figure 4] FIG. 2 is a schematic diagram showing a combination of ink droplets in an embodiment. [Figure 5] FIG. 10 is a schematic diagram showing penetration of ink droplets in an embodiment. [Figure 6] FIG. 10 is a schematic diagram illustrating a more detailed flow of the step of calculating the inkjet volume and distribution of ink droplets in each pixel groove based on the target film thickness, mesh parameters, and ink droplet-related parameters in one embodiment. [Figure 7] FIG. 2 is a schematic diagram showing classification of pixel grooves in an embodiment. [Figure 8] FIG. 1 is a block diagram illustrating the configuration of an apparatus for compensating for film thickness uniformity in OLED inkjet printing in one embodiment. [Figure 9] FIG. 2 is a diagram illustrating the internal configuration of a computer device according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] It should be understood that the specific examples described herein are for purposes of interpretation only and are not intended to limit the scope of the present application.

[0015] 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 terms used herein are for the purpose of describing particular examples only and are not intended to be limiting of the application. The terms "comprises" and "having" and any variations thereof in the specification and claims of this application and the foregoing description of the drawings are intended to cover a non-exclusive inclusion.

[0016] It should be noted that when an element is referred to as being "anchored" to another element, it may be directly connected to the other element, or there may be intervening elements. It should be noted that when an element is referred to as being "connected" to another element, it may be directly connected to the other element, or there may be intervening elements. Terms such as "vertical," "horizontal," "left," "right," etc., used herein are for descriptive purposes only.

[0017] In the drawings, the sizes of layers and regions may be exaggerated for clarity of illustration. Also, when a layer or element is referred to as being "on" another layer or substrate, it is understood that the layer or element can be directly on the other layer or substrate, or that one or more intervening layers can be present. Also, when a layer is referred to as being "between" two layers, it is understood that the layer can be the only layer between the two layers, or that one or more intervening layers can be present. Furthermore, like reference numerals refer to like elements throughout.

[0018] In the following examples, when a layer, region, or element is referred to as being "connected," this can be interpreted to mean that the layer, region, or element is not only directly connected, but also connected via other intervening components. For example, when layers, regions, elements, etc. are described as being connected or electrically connected, the layers, regions, elements, etc. may not only be directly connected or electrically connected, but may also be connected or electrically connected via another intervening layer, region, element, etc.

[0019] It is further understood that terms such as "comprise" or "have" specify the presence of stated features, integers, steps, operations, components, portions, or groups thereof, but do not exclude the possible presence or addition of one or more other features, integers, steps, operations, components, portions, or groups thereof.

[0020] One prior art technique involves modifying the condenser plate to change the solvent evaporation rate, thereby solving the problem of uneven film thickness caused by fast airflow at the edge of the substrate and different ink evaporation rates. While this method partially solves the problem of uneven film thickness during the drying process, the actual drying process requires precise control of the gas temperature, flow rate, and pressure, and also requires ensuring that the solvent in the ink evaporates without physically distorting the luminescent material remaining in the pixel grooves. This places high demands on the precision of the component devices, making the design difficult.

[0021] Another prior art involves improving the cross section of the heat source beam generated by the inkjet head to dry the ink, thereby making the solidification rate of the ink in the middle region of the pixel groove of the target substrate faster than the solidification rate of the edge region. However, although this method solves the problem of uneven film thickness during the drying process by drying the substrate to some extent, it is very difficult to precisely control the pressure during the actual drying process and ensure that the drying state is stable, so the display quality in different regions may not be consistent after the actual drying process, resulting in a deterioration of the display quality.

[0022] Another prior art technique uses a detection module to detect the thickness of a film layer, analyzes the difference in film thickness at various points on the surface of the film layer based on the detected film layer thickness data, and then corrects the number of ink droplets printed based on the analysis. However, in this solution, the compensation for the number of ink droplets printed does not include the subsequent drying process, and the subsequent drying and baking processes also cause the film thickness to be non-uniform in the pixel grooves. Furthermore, when only compensating for the number of ink droplets printed, the distribution of ink droplets is ignored, which causes the film thickness uniformity of the printed display image to be low.

[0023] The present application can be applied to a system such as that shown in FIG. 1. The system includes an ink droplet observation device 10, an OLED inkjet device 20, a film thickness detector 30, a drying device 40, a substrate 50, and a processor 60. The OLED inkjet device 20 includes multiple inkjet heads 21. The ink droplet observation device 10 may also include a CCD high-speed camera and a flash unit. The ink droplet observation device 10 captures and analyzes images of the flight trajectories of ink droplets from the inkjet head. From the captured images, the trajectories of ink droplets ejected from the inkjet head are obtained, and data such as ink droplet velocity, ink droplet volume, satellite ink droplets, and tailing are measured to determine the quality of the ink. The system then adjusts the voltage of the inkjet head control board, the inkjet head control waveform, and the ink to improve printing accuracy.

[0024] The OLED inkjet device 20 is a type of device similar to inkjet printing, which prints OLED pixel dots directly onto a glass or plastic substrate using a moving platform and an inkjet head according to a user-defined inkjet pattern. The OLED inkjet device 20 typically uses an inkjet head with multiple inkjet holes, with one or more inkjet heads containing several thousand inkjet holes.

[0025] Drying unit 40 is a drying chamber used to dry the pattern having a display area, the display area being wetted with an OLED material dissolved or suspended in a volatile carrier liquid.

[0026] The film thickness detector 30 uses the lighting system of the device to provide different light colors and illuminance to the components being detected. It also uses a high-resolution CCD camera to capture images of the components being detected, transmits them to a computer processing system, compares them with the grayscale of a standard image, and performs discriminant analysis to finally output the detection results. This is used to measure the uniformity of the film thickness of OLED products. The film thickness detector 30 is a conventional device that outputs corresponding film thickness measurement results. The film thickness detector 30 compares the position and size of the grayscale deviations in the image after grayscale processing of each pixel, thereby selecting pixels that differ in position and size from the grayscale images of other pixels, and outputs corresponding film thickness detection parameters based on the printing requirements.

[0027] After inkjet is completed, the OLED substrate can be transported to a drying device 40 for baking. The film thickness detector 30 can detect the thickness of the ink droplets in each pixel groove on the OLED substrate and the baked film thickness, and feed it back to the processor 60. The processor 60 controls the inkjet head 21 to perform compensatory inkjet based on the received feedback, so that the final film thickness reaches the target film thickness.

[0028] In one embodiment, as shown in FIG. 2, the present application provides a method for compensating film thickness uniformity in OLED inkjet printing, the method including the following steps:

[0029] In step 110, the target film thickness of the OLED, the mesh parameters of the pixel groove, and the parameters related to ink droplets of each inkjet head in the inkjet device are obtained, and the inkjet volume and distribution of the ink droplets in each pixel groove are calculated according to the target film thickness, the mesh parameters, and the parameters related to ink droplets.

[0030] This application is applied to the processor shown in Figure 1. First, each pixel groove on the substrate is meshed. Specifically, as shown in Figure 3, each pixel groove is divided into multiple meshed regions, and each pixel groove has 20 regions. The size of each region is the smallest print area that can be realized by the inkjet device. After meshing, mesh parameters for each pixel groove are obtained.

[0031] The processor first obtains various pre-stored parameters, specifically including a target film thickness of the OLED, mesh parameters of pixel grooves, and parameters related to ink droplets of each inkjet head in the inkjet device, and the parameters related to ink droplets include the volume of ink droplets ejected by each inkjet hole in each inkjet head.

[0032] In one embodiment, obtaining the target film thickness of the OLED, mesh parameters of pixel grooves, and parameters related to ink droplets of each inkjet head in the inkjet device includes controlling each inkjet head in the inkjet device to eject ink droplets, obtaining first images of the ink droplets, and determining the parameters related to ink droplets of each inkjet head based on the first images.

[0033] Specifically, different ink droplet materials may affect the volume of the ink droplets, and even the same holes may cause the volume of the ink droplets to change due to factors such as aging of the device. Therefore, in this embodiment, first, each inkjet head in the inkjet device is controlled to eject ink droplets, and an image of each ejected ink droplet is obtained and defined as a first image. Parameters related to the ink droplets of each inkjet head are identified based on the first image. For specific processes, please refer to the prior art.

[0034] After obtaining the target film thickness of the OLED, the mesh parameters of the pixel groove and the parameters related to the ink droplets of each inkjet head in the inkjet device, a weighting calculation is performed based on the target film thickness to obtain the volume and distribution of the ink droplets required for each mesh, that is, to obtain the inkjet volume and distribution of the ink droplets in each pixel groove.

[0035] In addition, each inkjet head in the inkjet device includes a plurality of inkjet holes, and each inkjet head can eject ink droplets of at least two different volumes through the corresponding plurality of inkjet holes; and calculating the inkjet volume and distribution status of the ink droplets in each pixel groove based on the target film thickness, mesh parameters, and parameters related to the ink droplets is Obtaining ink droplet volumes and linear combinations ejected by each inkjet head into each pixel groove; Calculating the inkjet volume and distribution of the ink droplets in each pixel groove based on the ink droplet volume and linear combination ejected by each inkjet head into each pixel groove, the target film thickness, mesh parameters, and parameters related to the ink droplets.

[0036] Specifically, through the obtained pixel meshing, the ink droplet volume of the minimum printable area of ​​each pixel groove after division is controlled by the driving waveform of the inkjet head and the switching of the inkjet holes, thereby realizing ink droplets of fixed but selectable volume for each minimum printable area, which means that the ink droplet volume of a single pixel groove is a linear combination of the ink droplet volume sizes of multiple minimum printable areas, as shown in Figure 4 for example. Figure 4 shows several combinations of printed ink droplets, and in specific implementation, various ink droplet combinations can be obtained by arranging and combining them based on each inkjet hole in the inkjet head.

[0037] In addition, obtaining the ink droplet volume and linear combination ejected by each inkjet head into each pixel groove is obtaining a difference between the ink droplet volume of each pixel groove and the volume of each pixel groove at the target film thickness; and performing sequential calculations based on the volume differences to obtain ink drop volumes and linear combinations for each pixel groove.

[0038] Specifically, the difference between the volume of the pixel groove and the volume of the pixel groove at the target film thickness is used as a cost function, and then, through sequential optimization calculations, a method for combining the size and distribution of the ink droplet volume in the pixel groove is obtained.

[0039] In step 120, ink is applied to each pixel groove based on the inkjet volume and distribution within each pixel groove.

[0040] In step 130, a baking process is performed on each pixel groove, and the film thickness of each mesh in each baked pixel groove is obtained.

[0041] Specifically, after obtaining the inkjet volume and distribution status of each pixel groove, the inkjet device is controlled to perform inkjet printing within each pixel groove, and after inkjet printing is completed, the inkjet-printed substrate is transported to a drying device and dried. The printing and drying processes may refer to conventional techniques and are not limited here.

[0042] 5, since inkjet printing is performed on different meshes, the film thickness at different positions may be different after blending, and the position and shape of each ink droplet before blending are as shown in M1 and M3, as the three ink droplets in M1 are the same size, and after the three ink droplets are blended, as shown in M2, the liquid surface at each mesh position is basically flat, and for the three ink droplets in M3, the middle ink droplet is large and the two side ink droplets are small, so after blending, the middle may be high and the two sides may be low. Therefore, in the present invention, after drying is completed, the thickness of the film in each mesh after drying is measured to obtain the film thickness of each mesh in each pixel groove.

[0043] In step 140, a compensation inkjet volume for each mesh in each pixel groove is determined based on the film thickness of each mesh in each pixel groove and the target film thickness, and inkjet is performed on each mesh in each pixel groove according to the compensation inkjet volume until the film thickness of each pixel groove reaches the target film thickness.

[0044] Based on the film thickness of each mesh obtained in step 130, the difference between the film thickness of each mesh in each pixel groove and the target film thickness is determined, a compensation inkjet volume for each mesh is determined, and ink is jetted for each mesh in each pixel groove according to the compensation inkjet volume. After inkjet is completed, a baking process is performed again, and the film thickness of each baked mesh is obtained again. Based on the film thickness of each mesh obtained again, the difference between the film thickness and the target film thickness is determined, and if a difference exists, a compensation inkjet volume is determined again. This process is repeated until the film thickness of each pixel groove reaches the target film thickness.

[0045] According to the above-described method for compensating for film thickness uniformity in OLED inkjet printing, the target film thickness of the OLED, pixel groove mesh parameters, and ink droplet parameters of each inkjet head in the inkjet device are obtained, and then the inkjet volume and distribution of ink droplets in each pixel groove are calculated based on the target film thickness, mesh parameters, and ink droplet parameters. Each pixel groove is then inkjetted based on the inkjet volume and distribution in each pixel groove. Each pixel groove is then baked, and the film thickness of each mesh in each baked pixel groove is obtained. A compensation inkjet volume for each mesh in each pixel groove is determined based on the film thickness of each mesh in each pixel groove and the target film thickness. Then, inkjet is performed on each mesh in each pixel groove according to the compensation inkjet volume until the film thickness of each pixel groove reaches the target film thickness. According to the above-described method, the present invention meshes each pixel groove, calculates the ink droplet volume and distribution for each mesh in each pixel groove, and after baking, the film thickness of each pixel groove is obtained. Based on the film thickness of each pixel groove and the target film thickness, a compensation inkjet volume for each mesh in each pixel groove is determined, and inkjet is then performed again. In this way, film thickness errors due to the baking process can be avoided. The use of an improved drying device in the prior art solves the problem of design complexity caused by non-uniform film thickness, reducing design complexity while ensuring good film thickness uniformity. Furthermore, by adding a drying process to the flow, this embodiment solves the problem of non-uniform film thickness within pixel grooves caused by the prior art print compensation technology not taking into account processes such as drying and baking, and improves the accuracy of film thickness uniformity detection.

[0046] In one embodiment, as shown in FIG. 6, the step of calculating the inkjet volume and distribution of ink droplets in each pixel groove based on the target film thickness, mesh parameters, and ink droplet-related parameters includes: In step 111, acquiring an image of a substrate on which the pixel grooves are located, and classifying each pixel groove into a corresponding pixel groove type based on the image; In step 112, calculating the inkjet volume and distribution of ink droplets in each pixel groove based on the target film thickness, mesh parameters, ink droplet-related parameters, and each pixel groove type.

[0047] Specifically, taking into account the influence of different pixel groove positions, in this embodiment, each pixel groove is classified into different types based on its position. For example, referring to FIG. 7, the position of each pixel groove on the substrate is identified based on an acquired image of the substrate, and each pixel groove is classified into a corresponding pixel groove type. The pixel groove types include at least one of single-edge pixel grooves adjacent to one edge of the substrate (e.g., the pixel groove designated by A2 in FIG. 7), double-edge pixel grooves adjacent to two edges of the substrate (e.g., the pixel groove designated by A1 in FIG. 7), and internal pixel grooves located inside the substrate (e.g., the pixel groove designated by A3 in FIG. 7). In specific embodiments, pixel grooves can be classified into other types. After identifying the type of each pixel groove, the inkjet volume and distribution of ink droplets in each pixel groove are calculated based on the target film thickness, mesh parameters, ink droplet parameters, and the type of each pixel.

[0048] In one embodiment, calculating the inkjet volume and distribution of ink droplets in each pixel groove based on the ink droplet volume and linear combination ejected by each inkjet head into each pixel groove, the target film thickness of the OLED, mesh parameters, and ink droplet-related parameters, Obtaining an inkjet matrix of a plurality of pixel grooves that can be completed per unit step number of each inkjet head based on the ink droplet volume and linear combination ejected by each inkjet head into each pixel groove; and obtaining the minimum number of inkjet steps, and thus the inkjet volume and distribution of ink droplets in each pixel groove, based on the number of pixel grooves on the substrate and the inkjet matrix of multiple pixel grooves that can be completed per unit step number.

[0049] Specifically, each inkjet orifice has two or more ink droplet volume sizes, and there is a slight difference in the volume ejected by each inkjet orifice. In order to ensure the accuracy of the ink droplet volume and increase the printing efficiency by using the minimum number of steps during printing, a matrix mathematics execution optimization method is used to generate printing landing point and waveform selection data based on the acquired ink droplet parameters, the inkjet volume and distribution of ink droplets in each pixel groove acquired in step 110, and the coordinates of the pixel groove on the substrate as input.

[0050] Furthermore, during the printing process, each pixel groove cannot meet the printing requirements with a single movement of the inkjet head; one inkjet head array must simultaneously print multiple pixel grooves, requiring successive stepwise movement of the inkjet head, which leads to the issue of the minimum number of steps. Based on the inkjet volume and distribution of ink droplets in each pixel groove obtained in step 110, the ink droplet size distributions for multiple pixel grooves that can be maximally printed by one inkjet head array in one pass are combined into a single large ink droplet distribution matrix. Then, using an optimization method and matrix calculation to determine the minimum number of steps of inkjet head movement as the target function, waveform selection data corresponding to the final printing landing point and ink droplet volume size can be determined.

[0051] In addition, a particle swarm optimization algorithm is selected as the optimization method, which is a branch of evolutionary computation and a random search algorithm that simulates biological activities in nature. In using this method, the inkjet holes in the entire inkjet head array are regarded as "particles," and the corresponding search space is the inkjet volume and distribution of ink droplets in each pixel groove obtained in step 110. A global optimum value and a fitness function are set based on the minimum number of steps in the printing process for the entire substrate, and the optimum value is correspondingly updated once during the global search until the minimum number of printing steps that satisfies the termination condition is obtained. After the number of printing steps is obtained, a unique solution for the corresponding ink droplet volume size and distribution scheme can be identified.

[0052] determining a compensation inkjet volume for each mesh in each pixel groove based on the film thickness of each mesh in each pixel groove and the target film thickness, and inkjetting each mesh in each pixel groove according to the compensation inkjet volume until the film thickness of each pixel groove reaches the target film thickness; Acquiring the target film thickness and film thickness supplement parameters for each mesh film thickness in each pixel groove that has been previously baked; obtaining an ink droplet replenishment volume for each pixel groove based on the film thickness replenishment parameter and a preset weighting parameter; and sequentially optimizing the ink droplet refill volume of each pixel groove to obtain a compensation ink droplet volume and distribution combination scheme for each pixel groove.

[0053] Further, obtaining the ink droplet replenishment volume of each pixel groove based on the film thickness replenishment parameter and the preset weighting parameter is Identifying a type of each pixel groove and identifying a weighting parameter corresponding to each pixel groove film thickness fill parameter based on each pixel groove type.

[0054] TIFF0007777688000001.tif53170

[0055] TIFF0007777688000002.tif23167

[0056] In this way, the inkjet volume corresponding to each pixel groove in area A1 can be determined.

[0057] TIFF0007777688000003.tif57170

[0058] TIFF0007777688000004.tif47169

[0059] TIFF0007777688000005.tif40169

[0060] where J(w) is the cost function, m is the total number of pixel grooves, w is the number of each mesh ink drop in the pixel groove, and y i is the ink drop refill volume in the pixel groove (V calculated as above) A1 , V A2 , V A3 (obtained from w new are the parameters currently used, and w old is the parameter used last time, η is the learning rate, and ▽ w J(w) is a gradient operator, which is obtained by an existing algorithm based on the cost function J(w), and X i represents the parameters related to the ink droplets of each inkjet head. i The product of w and represents the inkjet volume per unit mesh, and the combination of the inkjet volumes of each mesh in each pixel groove constitutes the inkjet volume and distribution of each pixel groove. Note that in the iteration process, iteration is performed with the goal of minimizing the cost function J(w), and finally X i The values ​​of and w were obtained, i.e., the inkjet head (or inkjet volume per inkjet) and the number of inkjet prints used in each mesh were obtained.

[0061] In one embodiment, the minimum number of inkjet steps is specified, i.e., the inkjet heads to be used, i.e., the target inkjet head combination, is specified. The minimum inkjet is the distance that the inkjet holes must move to move from the first printing point to the last printing point during the printing process. Then, each inkjet head is controlled to print on the target pixel groove according to the specified target inkjet head combination and compensation inkjet volume. Specifically, a print image of the target pixel groove is first generated according to the target inkjet head combination and the compensation inkjet volume. The print image is a pre-printed image corresponding to the size and position distribution of the ink droplet volume that can be ejected by the target inkjet hole combination. Then, each inkjet hole is controlled to print on each pixel groove based on the print image of each pixel groove.

[0062] As can be understood, although the steps in the flowcharts according to the above-described embodiments are shown sequentially in the order indicated by the arrows, these steps do not necessarily have to be performed sequentially in the order indicated by the arrows. The execution of these steps is not limited to a strict order and may be performed in other orders unless explicitly stated otherwise. Furthermore, at least some of the steps in the flowcharts according to the above-described embodiments may include multiple steps or multiple stages, and these steps or stages do not necessarily have to be performed simultaneously but may be performed at different times. The execution order of these steps or stages does not necessarily have to be sequential but may be alternating with other steps or at least some of the steps or stages of other steps.

[0063] Based on the same inventive concept, the embodiments of the present application further provide an apparatus for compensating for thickness uniformity in OLED inkjet printing, for realizing the method for compensating for thickness uniformity in OLED inkjet printing described above. The technical solutions provided by the apparatus for solving the problems are similar to the technical solutions described in the above method, so that the specific limitations of one or more embodiments of the OLED inkjet control device provided below can be referred to the limitations of the method for compensating for thickness uniformity in OLED inkjet printing described above, and will not be repeated here.

[0064] In one embodiment, as shown in FIG. 8, an apparatus for compensating thickness uniformity of OLED inkjet printing is provided, which includes the following modules:

[0065] The acquisition module 810 is used to acquire the target film thickness of the OLED, the mesh parameters of the pixel groove, and the parameters related to ink droplets of each inkjet head in the inkjet device, and calculate the inkjet volume and distribution of the ink droplets in each pixel groove according to the target film thickness of the OLED, the mesh parameters, and the parameters related to ink droplets.

[0066] The inkjet module 820 is used to inkjet each pixel groove according to the inkjet volume and distribution in each pixel groove.

[0067] The film thickness acquisition module 830 is used to perform a baking process on each pixel groove and acquire the film thickness of each mesh in each baked pixel groove.

[0068] The refill module 840 is used to determine a compensation inkjet volume for each mesh in each pixel groove based on the film thickness of each mesh in each pixel groove, and inkjet each mesh in each pixel groove according to the compensation inkjet volume until the film thickness of each pixel groove reaches the target film thickness.

[0069] In one embodiment, the acquisition module 810: The inkjet head is used to control each inkjet head in an inkjet device to eject ink droplets, obtain a first image of the ink droplets, and identify parameters related to the ink droplets of each inkjet head based on the first image.

[0070] In one embodiment, the acquisition module 810: acquiring an image of the substrate on which the pixel grooves are located, and classifying each pixel groove into a corresponding pixel groove type based on the image; Based on the target film thickness, mesh parameters, ink drop related parameters and each pixel groove type, ink jet volume and distribution of ink drops within each pixel groove are used to calculate.

[0071] In one embodiment, the types of pixel grooves include at least one of a single-edge pixel groove adjacent to one edge of the substrate, a double-edge pixel groove adjacent to two edges of the substrate, and an internal pixel groove located inside the substrate.

[0072] In one embodiment, the replenishment module 840 includes: Acquire the target film thickness and film thickness supplement parameters for each mesh film thickness in each pixel groove that has been previously baked; obtaining an ink droplet replenishment volume for each pixel groove based on the film thickness replenishment parameter and a preset weighting parameter; Based on the ink drop refill volume of each pixel groove, iterative optimization is performed to obtain a compensation ink drop volume and distribution combination scheme for each pixel groove.

[0073] In one embodiment, the replenishment module 840 includes: The type of each pixel groove is identified and used to identify a weighting parameter corresponding to each pixel groove film thickness fill parameter based on each pixel groove type. In one embodiment, each inkjet head in the inkjet device includes a plurality of inkjet holes, and each inkjet head can eject ink droplets of at least two different volumes through the corresponding plurality of inkjet holes. The acquisition module 810: Acquire the ink droplet volume and linear combination ejected by each inkjet head into each pixel groove; It is used to calculate the inkjet volume and distribution of ink droplets in each pixel groove based on the ink droplet volume and linear combination ejected by each inkjet head into each pixel groove, the target film thickness, mesh parameters and ink droplet-related parameters.

[0074] In one embodiment, the acquisition module 810: Obtaining the difference between the ink droplet volume in each pixel groove and the volume of each pixel groove at the target film thickness; Based on the volume differences, iterative calculations are performed to obtain the ink drop volume and linear combination for each pixel groove.

[0075] In one embodiment, the acquisition module 810: Obtain an inkjet matrix of a plurality of pixel grooves that can be completed per unit step number of each inkjet head based on the ink droplet volume and linear combination ejected by each inkjet head into each pixel groove; Based on the number of pixel grooves in the substrate and the inkjet matrix of multiple pixel grooves that can be completed per unit step, this is used to obtain the minimum number of inkjet steps, and therefore the inkjet volume and distribution of ink droplets within each pixel groove.

[0076] In one embodiment, the size of each mesh within each pixel groove is the size of the smallest print area that the inkjet device can achieve.

[0077] Each module in the above-mentioned OLED inkjet printing film thickness uniformity compensation device can be realized in whole or in part by software, hardware, or a combination thereof. Each module can be embedded in or independent from a processor in a computer device in a hardware form, or can be stored in a memory in a computer device in a software form, so that the processor can call and execute the operations corresponding to each module.

[0078] In one embodiment, a computer device is provided, the computer device being a server, the internal configuration of which is shown in FIG. 9 . The computer device includes a processor, a memory, and a network interface, all connected by a system bus. The processor of the computer device is used to provide calculation and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. An operating system, a computer program, and a database are stored in the non-volatile storage medium. The internal memory provides an environment for the execution of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store data such as a target film thickness, pixel groove mesh parameters, and parameters related to ink droplets of each inkjet head in an inkjet device. The network interface of the computer device is used to communicate with an external terminal via a network connection. When the computer program is executed by the processor, it performs steps of a method for compensating for film thickness uniformity in OLED inkjet printing.

[0079] Those skilled in the art will understand that the configuration shown in FIG. 9 is a block diagram of only a portion of the configuration relevant to the solution of the present application and does not limit the computing devices to which the solution of the present application may be applied; a particular computing device may include more or fewer components than those shown in the figure, may combine some components, or may have a different arrangement of components.

[0080] In one embodiment, a computing device is provided, the computing device including a memory and a processor, a computer program stored in the memory, the processor performing the following steps when executing the computer program:

[0081] obtaining a target film thickness of the OLED, mesh parameters of the pixel grooves, and parameters related to ink droplets of each inkjet head in the inkjet device; and calculating an inkjet volume and distribution of ink droplets in each pixel groove based on the target film thickness, mesh parameters, and parameters related to ink droplets; Ink-jetting is performed for each pixel groove based on the ink-jet volume and distribution status within each pixel groove; A baking process is performed on each pixel groove, and the film thickness of each mesh in each baked pixel groove is obtained. A compensation inkjet volume for each mesh in each pixel groove is determined based on the film thickness of each mesh in each pixel groove and the target film thickness, and inkjet is performed on each mesh in each pixel groove according to the compensation inkjet volume until the film thickness of each pixel groove reaches the target film thickness.

[0082] In one embodiment, when the processor executes the computer program, it further performs the following steps:

[0083] Each inkjet head in an inkjet device is controlled to eject ink droplets, a first image of the ink droplets is acquired, and parameters relating to the ink droplets of each inkjet head are identified based on the first image.

[0084] In one embodiment, when the processor executes the computer program, it further performs the following steps:

[0085] acquiring an image of the substrate on which the pixel grooves are located, and classifying each pixel groove into a corresponding pixel groove type based on the image; Based on the target film thickness, mesh parameters, ink drop related parameters and each pixel groove type, the ink jet volume and distribution of ink drops within each pixel groove is calculated.

[0086] In one embodiment, the types of pixel grooves include at least one of single-edge pixel grooves adjacent to one edge of the substrate, double-edge pixel grooves adjacent to two edges of the substrate, and internal pixel grooves located inside the substrate.

[0087] In one embodiment, when the processor executes the computer program, it further performs the following steps:

[0088] Acquire the target film thickness and film thickness supplement parameters for each mesh film thickness in each pixel groove that has been previously baked; obtaining an ink droplet replenishment volume for each pixel groove based on the film thickness replenishment parameter and a preset weighting parameter; Based on the ink drop refill volume of each pixel groove, iterative optimization is performed to obtain a compensation ink drop volume and distribution combination scheme for each pixel groove.

[0089] In one embodiment, when the processor executes the computer program, it further performs the following steps:

[0090] A type of each pixel groove is identified, and a weighting parameter corresponding to each pixel groove film thickness fill parameter is identified based on each pixel groove type.

[0091] In one embodiment, each inkjet head in the inkjet device includes a plurality of inkjet holes, and each inkjet head can eject ink droplets of at least two different volumes through the corresponding plurality of inkjet holes.

[0092] When the processor executes the computer program, it further performs the following steps:

[0093] Acquire the ink droplet volume and linear combination ejected by each inkjet head into each pixel groove; The inkjet volume and distribution of the ink droplets in each pixel groove are calculated based on the ink droplet volume and linear combination ejected by each inkjet head into each pixel groove, the target film thickness, mesh parameters, and ink droplet-related parameters.

[0094] In one embodiment, when the processor executes the computer program, it further performs the following steps:

[0095] Obtaining the difference between the ink droplet volume in each pixel groove and the volume of each pixel groove at the target film thickness; Based on the volume differences, iterative calculations are performed to obtain the ink drop volume and linear combination for each pixel groove.

[0096] In one embodiment, when the processor executes the computer program, it further performs the following steps:

[0097] Obtain an inkjet matrix of a plurality of pixel grooves that can be completed per unit step number of each inkjet head based on the ink droplet volume and linear combination ejected by each inkjet head into each pixel groove; Based on the number of pixel grooves in the substrate and the inkjet matrix of multiple pixel grooves that can be completed per unit step number, the minimum number of inkjet steps, and thus the inkjet volume and distribution of ink droplets in each pixel groove, are obtained.

[0098] In one embodiment, a computer-readable storage medium is provided, having a computer program stored therein, the computer program, when executed by a processor, performing the steps of the method for compensating for film thickness uniformity in OLED inkjet printing as described in any of the above embodiments.

[0099] Those skilled in the art will understand that implementing all or part of the processes of the methods described above can be accomplished by instructing relevant hardware using a computer program. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, can include the processes of the above method embodiments. Furthermore, any reference to memory, database, or other medium used in the embodiments provided herein can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM), external cache memory, etc. For purposes of explanation and not limitation, RAM may be of various types, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The databases in the embodiments provided herein may include at least one of a relational database and a non-relational database. Non-relational databases may include, but are not limited to, distributed databases based on blockchain. The processors in the embodiments provided herein may include, but are not limited to, a general-purpose processor, a central processor, a graphics processor, a digital signal processor, programmable logic, data processing logic based on quantum computing, etc.

[0100] The technical features of the above embodiments can be combined in any desired manner, and for the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, any combination should be considered within the scope of the present specification.

[0101] The above examples only show some embodiments of the present application, and although the description is specific and detailed, it should not be understood as limiting the patent scope of the present application. It should be noted that a person skilled in the art can make many modifications and improvements without departing from the concept of the present application, and all of these fall within the scope of protection of the present application. Therefore, the scope of protection of the present application should be determined based on the appended claims.

Claims

1. 1. A method for compensating for film thickness uniformity in OLED inkjet printing, comprising: The method comprises: Dividing each pixel groove on the substrate into a plurality of meshed regions, the size of each region being the smallest printable region that can be realized by the inkjet device, and after meshing, obtaining mesh parameters for each pixel groove; Acquiring a target film thickness of the OLED, mesh parameters of pixel grooves, and parameters related to ink droplets of each inkjet head in an inkjet device, and calculating an inkjet volume and distribution status of ink droplets in each pixel groove based on the target film thickness, mesh parameters, and parameters related to ink droplets; performing ink jetting on each pixel groove based on the ink jet volume and distribution status within each pixel groove; performing a baking process on each pixel groove and acquiring the film thickness of each mesh in each baked pixel groove; determining a compensation inkjet volume for each mesh in each pixel groove based on the film thickness of each mesh in each pixel groove and the target film thickness, and inkjetting each mesh in each pixel groove according to the compensation inkjet volume until the film thickness of each pixel groove reaches the target film thickness; determining a compensation inkjet volume for each mesh in each pixel groove based on the film thickness of each mesh in each pixel groove and the target film thickness, and inkjetting each mesh in each pixel groove according to the compensation inkjet volume until the film thickness of each pixel groove reaches the target film thickness; Acquiring the target film thickness and film thickness supplement parameters for each mesh film thickness in each pixel groove that has been previously baked; obtaining an ink droplet replenishment volume for each pixel groove based on the film thickness replenishment parameter and a preset weighting parameter; and using the difference between the ink drop replenishment volume of each pixel groove and the ink drop volume size and distribution combination plan of each mesh within the pixel groove as a cost function, and performing sequential optimization to obtain a compensation ink drop volume and distribution combination plan of each mesh within each pixel groove.

2. Obtaining the target film thickness of the OLED, mesh parameters of pixel grooves, and parameters related to ink droplets of an inkjet head in an inkjet device includes:

2. The method of claim 1, further comprising controlling each inkjet head in an inkjet device to eject ink droplets, acquiring a first image of the ink droplets, and identifying parameters related to the ink droplets of each inkjet head based on the first image.

3. calculating an inkjet volume and distribution of ink droplets in each pixel groove based on the target film thickness, mesh parameters, and ink droplet-related parameters; acquiring an image of a substrate on which the pixel grooves are located, and classifying each pixel groove into a corresponding pixel groove type based on the image; and calculating an inkjet volume and distribution of ink droplets within each pixel groove based on the target film thickness, mesh parameters, ink droplet parameters, and each pixel groove type.

4. 4. The method of claim 3, wherein the pixel groove types include at least one of a single-edge pixel groove adjacent to one edge of the substrate, a double-edge pixel groove adjacent to two edges of the substrate, and an internal pixel groove located inside the substrate.

5. obtaining an ink droplet replenishment volume for each pixel groove based on the film thickness replenishment parameter and a preset weighting parameter; 2. The method of claim 1, further comprising identifying a type of each pixel groove and identifying a weighting parameter corresponding to each pixel groove film thickness fill parameter based on the type of each pixel groove.

6. Each inkjet head in the inkjet device includes a plurality of inkjet holes, and each inkjet head can eject ink droplets of at least two different volumes through the corresponding plurality of inkjet holes; and calculating the inkjet volume and distribution status of the ink droplets in each pixel groove based on the target film thickness, mesh parameters, and parameters related to the ink droplets; Obtaining ink droplet volumes and linear combinations ejected by each inkjet head into each pixel groove; calculating an inkjet volume and distribution of ink droplets in each pixel groove based on the ink droplet volume and linear combination ejected by each inkjet head into each pixel groove, the target film thickness, mesh parameters, and ink droplet-related parameters; 2. The method of claim 1, wherein pixel groove meshing provides ink drops of fixed, selectable volume size in the minimum printable area of ​​each pixel groove after partitioning, the ink drop volume of a single pixel groove being a linear combination of the ink drop volume sizes of multiple said minimum printable areas.

7. The ink droplet volume and linear combination thereof ejected by each inkjet head into each pixel groove are obtained by: obtaining a difference between the ink droplet volume of each pixel groove and the volume of each pixel groove at the target film thickness; and performing iterative calculations based on the volume differences to obtain ink drop volumes and linear combinations for each pixel gutter.

8. calculating an inkjet volume and distribution of ink droplets in each pixel groove based on the ink droplet volume and linear combination ejected by each inkjet head into each pixel groove, a target film thickness of the OLED, mesh parameters, and parameters related to ink droplets; Obtaining an inkjet matrix of a plurality of pixel grooves that can be completed per unit step number of each inkjet head based on the ink droplet volume and linear combination ejected by each inkjet head into each pixel groove; and obtaining the minimum number of inkjet steps, and thus the inkjet volume and distribution of ink droplets in each pixel groove, based on the number of pixel grooves on the substrate and the inkjet matrix of multiple pixel grooves that can be completed per unit step.

9. 9. The method according to claim 1, wherein the size of each mesh in each pixel groove is the size of the smallest print area that can be realized by an inkjet device.

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