A pixel simulation model optimization method and modeling method of an electrowetting display device

Abstract

The application discloses a kind of pixel simulation model optimization method and modeling method of electrowetting display device, the method is to establish electrowetting pixel unit simulation model using COMSOL software, simulate the movement of color ink in pixel cell, provide guidance for the development of new driving waveform through the color ink movement, in electrowetting pixel unit, consider that color ink is incompressible, non-permeable, does not carry out chemical reaction, Newton's laminar flow model, use PDE to construct color ink model, color ink model is characterized by mass momentum balance, improve the calculation accuracy of simulation model;The method also includes setting grid migration rate X, for improving the coupling accuracy of phase field and laminar flow field in physical field, so that the output fluid mass is conserved.

Description

Technical Field

[0001] This invention relates to an electrowetting display technology, and more particularly to a pixel simulation model of an electrowetting display device. Background Technology

[0002] Electrowetting is a technique that uses an electric field to manipulate the movement of liquids. By applying an electric field to the surface of a dielectric material and changing the contact angle, the liquid undergoes directional movement, deformation, and splitting according to certain rules. Electrowetting display technology features millisecond-level response times, rich colors, and high reflectivity. As a next-generation display device, electrowetting has significant development potential. However, current research on two-dimensional simulation models for electrowetting is limited, and problems such as low model accuracy, non-convergence of calculation results, reduced fluid mass, and excessively long computation times for high-precision calculations are common. This results in an incomplete understanding of electrowetting research.

[0003] Currently, COMSOL software is used to establish a simulation model of the electrowetting display pixel unit. During the simulation, the suggested values ​​given by COMSOL software are not applicable to electrowetting. For example, the default mesh mobility X is 1 (m*s / kg). The value of mesh mobility X is too large, which makes it impossible to capture the interface motion correctly, resulting in low coupling accuracy between the phase field and the laminar flow field. This leads to serious non-conservation of the overall fluid mass during the simulation. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, this invention provides a pixel simulation model optimization method and modeling method for electrowetting display devices.

[0005] The technical solution adopted by this invention to solve its technical problem is:

[0006] An optimization method for pixel simulation models of electrowetting display devices is disclosed. This method utilizes COMSOL software to establish a simulation model of the electrowetting pixel unit, simulating the movement of colored ink within the pixel cell. The movement of the colored ink provides guidance for developing new driving waveforms. In the electrowetting pixel unit, the colored ink is considered incompressible, non-permeable, non-chemically reactive, and follows a Newtonian laminar flow model. A PDE (Polymerization-Derivative Analysis) is used to construct the colored ink model, which is characterized by mass-momentum balance using continuity equations and the Navier-Stokes equations, as shown below:

[0007] ,

[0008] in, p It is the fluid density. u Where t is the fluid velocity and t is time;

[0009] ,

[0010] in, It's pressure. It is viscous force. F To combine external forces, It is an inertial force;

[0011] The resultant external force F The formula is: Among them, F st Let pg be the surface tension, pg be gravity, and F be the force of gravity. vf It is an electrostatic volume force;

[0012] The electrostatic force F vf The divergence of the Maxwell stress tensor is calculated using the following formula: Among them, Z ij For a tensor, the following formula is satisfied: Where E is the electric field strength, D is the electric flux density, I is the identity matrix, and Z is a constant. In the two-dimensional simulation model, the tensor Z... ij The matrix expression is: in, The dielectric constant of free space, E is the relative permittivity. x E represents the electric field intensity on the horizontal axis of the two-dimensional model. y The electric field intensity is represented by the vertical axis of the two-dimensional model.

[0013] The electrostatic volume force F vf The calculation formula is: .

[0014] This method includes setting a mesh mobility X, which satisfies the following formula: V max This represents the maximum speed at which the colored ink moves. is the surface tension coefficient.

[0015] A pixel simulation modeling method for an electrowetting display device, employing the aforementioned optimization method, comprises the following steps:

[0016] S1. Establish a geometric model: Select and establish a two-dimensional model for the colored inks;

[0017] S2. Introducing material properties of the solution domain: Add materials from the COMSOL simulation software material library, including colored ink, polar liquid, pixel wall, substrate thickness, indium tin oxide electrode and hydrophobic insulating layer. The size of the colored ink is 6*130um, the size of the polar liquid is 42*160um, the size of the pixel wall is 8*15um, and the substrate thickness is 2*160um. Within a discrete individual pixel unit, the colored ink, polar liquid, indium tin oxide electrode and hydrophobic insulating layer form a stack structure.

[0018] S3. Define the control function: Use continuity equations and Navier-Stokes equations to optimize and adjust the simulation model;

[0019] S4. Set boundary conditions: Select a physical field, and add the coupling of laminar flow field, phase field and electrostatic field in the physical field. The laminar flow field and phase field together regulate the velocity and deformation of liquid motion, etc. The electrostatic field provides the electric field for the change of contact angle. The mesh mobility X is used to improve the coupling accuracy of laminar flow field and phase field.

[0020] S5. Plan the mesh generation: Select a low-density mesh shape;

[0021] S6. Solution Model: Select a computational model and an iterative solution algorithm for solving the problem;

[0022] S7. Generate Report Results: Generate a two-dimensional plotting group, export the report, and export the setup process and results as a PDF document.

[0023] The beneficial effects of this invention are as follows: This invention utilizes COMSOL software to establish a simulation model of electrowetting pixel units, simulating the movement of colored ink within the pixel units. The movement of the colored ink provides guidance for developing new driving waveforms. In the electrowetting pixel units, the colored ink is considered incompressible, non-permeable, non-chemically reactive, and follows a Newtonian laminar flow model. PDE is used to construct the colored ink model, improving the simulation accuracy of the colored ink model. Simultaneously, the mesh mobility X is adjusted to improve the coupling accuracy between the phase field and the laminar flow field in the physical field, thereby ensuring the conservation of the output fluid mass. Attached Figure Description

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0025] Figure 1 It is a simulation model diagram of existing color ink technology;

[0026] Figure 2 This is a simulation model diagram of the colored ink of the present invention;

[0027] Figure 3 yes Figure 2 Statistical charts of test results;

[0028] Figure 4 This is a flowchart of the steps of the present invention. Detailed Implementation

[0029] An optimization method for pixel simulation models of electrowetting display devices is disclosed. This method utilizes COMSOL software to establish a simulation model of the electrowetting pixel unit, simulating the movement of colored ink within the pixel cell. The movement of the colored ink provides guidance for developing new driving waveforms. In the electrowetting pixel unit, the colored ink is considered incompressible, non-permeable, non-chemically reactive, and follows a Newtonian laminar flow model. Partial differential equations (PDEs) are used to construct the colored ink model, improving the simulation accuracy. The colored ink model is characterized by mass-momentum balance using continuity equations and the Navier-Stokes equations, as shown in the following formulas:

[0030] ,

[0031] in, p It is the fluid density. u Where t is the fluid velocity and t is time;

[0032] ,

[0033] in, It's pressure. It is viscous force. F To combine external forces, It is an inertial force;

[0034] The resultant external force F The formula is: Among them, F st Let pg be the surface tension, pg be gravity, and F be the force of gravity. vf It is an electrostatic volume force;

[0035] The electrostatic force F vf The divergence of the Maxwell stress tensor is calculated using the following formula: Among them, Z ij For a tensor, the following formula is satisfied: Where E is the electric field strength, D is the electric flux density, I is the identity matrix, and Z is a constant. In the two-dimensional simulation model, the tensor Z... ij The matrix expression is: in, The dielectric constant of free space, E is the relative permittivity. x E represents the electric field intensity on the horizontal axis of the two-dimensional model. y The electric field intensity is represented by the vertical axis of the two-dimensional model.

[0036] The electrostatic volume force Fvf The calculation formula is: .

[0037] This method includes setting a grid migration rate X. A value that is too small will lead to numerical instability, while a value that is too large will prevent the correct capture of interface motion. The grid migration rate X satisfies the following formula: V max This represents the maximum speed at which the colored ink moves. It is the surface tension coefficient, used to improve the coupling accuracy of the phase field and laminar flow field in the physical field, thereby conserving the mass of the output fluid.

[0038] This method includes setting interface thickness control parameters. E This is used to stabilize the output value and ensure that the interface motion can be correctly captured. (The interface thickness control parameter is mentioned twice.) E If the value is too small, it may cause fluctuations in the value; if the interface thickness control parameter is too large, it may cause the value to fluctuate. E The value of the interface thickness control parameter may not accurately capture interface motion. E satisfy, , where h max This is the size of the largest grid cell.

[0039] Reference Figures 1 to 3 The electric field strength E was set to 10V, the duration t to 0.5s, and the test result step size to 0.1s. When using the recommended values ​​for fluid simulation in COMSOL software, the mesh mobility X is 1 (m*s / kg), such as... Figure 1 As shown, the colored ink represents the darker areas, and the polar liquid represents the lighter areas. Figure 1 The left side of the diagram shows the movement of the colored ink within the time interval 0s to 0.5s, while the right side shows the mass conservation of the colored ink. In the initial simulation, the mass of the polar liquid increased by 10.72%, the mass of the colored ink decreased by 94.35%, and the overall mass increased by 1.11%, indicating that the overall mass is not conserved. This invention introduces the maximum velocity V during the movement of the colored ink. max The parameter values ​​satisfy the formula: Maximum speed V max As a constraint condition for adjusting parameters, it can effectively improve the problem of quality variation during the simulation process. After using the optimization method of this invention, such as Figure 2 As shown, Figure 2 The left side of the figure shows the movement of the colored ink within the time interval of 0s to 0.5s, and the right side shows the mass conservation of the colored ink. The mass of the polar liquid increases slightly by 0.029%, while the mass of the ink decreases by only 0.254%, and the overall mass increases by 0.00291%. It can be approximately assumed that there is no problem of mass non-conservation in electrowetting in the simulation model.

[0040] Reference Figure 3 When the simulation time was further increased to 10 seconds, the total mass of the fluid did not change significantly. After the pixel units in the simulation model were driven for 10 seconds, the overall mass changed by -0.03217%. This proves that the optimization method of the present invention can indeed effectively improve the mass non-conservation problem in the electrowetting simulation model. It can effectively improve the convergence and robustness of the two-dimensional electrowetting simulation model.

[0041] A pixel simulation modeling method for an electrowetting display device, employing the aforementioned optimization method, comprises the following steps:

[0042] S1. Establish a geometric model: Select and establish a two-dimensional model for the colored inks;

[0043] S2. Introducing material properties of the solution domain: Add materials from the COMSOL simulation software material library, including colored ink, polar liquid, pixel wall, substrate thickness, indium tin oxide electrode and hydrophobic insulating layer. The size of the colored ink is 6*130um, the size of the polar liquid is 42*160um, the size of the pixel wall is 8*15um, and the substrate thickness is 2*160um. Within a discrete individual pixel unit, the colored ink, polar liquid, indium tin oxide electrode and hydrophobic insulating layer form a stack structure.

[0044] S3. Define the control function: Use continuity equations and Navier-Stokes equations to optimize and adjust the simulation model;

[0045] S4. Set boundary conditions: Select the physical field, and add the coupling of laminar flow field, phase field and electrostatic field in the physical field. The laminar flow field and phase field jointly regulate the velocity, deformation and other properties of the liquid motion. The electrostatic field provides the electric field for the change of contact angle. The mesh mobility X is used.

[0046] S5. Plan the mesh generation: Select a low-density mesh shape;

[0047] S6. Solution Model: Select a computational model and an iterative solution algorithm for solving the problem;

[0048] S7. Generate Report Results: Generate a two-dimensional plotting group, export the report, and export the setup process and results as a PDF document.

[0049] This invention utilizes COMSOL simulation software to establish an electrowetting pixel simulation model, simulating the movement of liquid within the pixel unit. The model's accuracy is improved, providing guidance for the development of new driving waveforms.

[0050] The above embodiments do not limit the scope of protection of this invention. All equivalent modifications and variations made by those skilled in the art without departing from the overall concept of this invention are still within the scope of this invention.

Claims

1. A method for optimizing a pixel simulation model of an electrowetting display device, characterized in that... This method utilizes COMSOL software to establish a simulation model of the electrowetting pixel unit, simulating the movement of colored ink within the pixel cell. This ink movement provides guidance for developing new driving waveforms. In the electrowetting pixel unit, the colored ink is considered incompressible, non-permeable, non-chemically reactive, and follows a Newtonian laminar flow model. A PDE (Polymerization-Derivative Analysis) is used to construct the colored ink model, which is characterized by mass-momentum balance using the continuity equation and the Navier-Stokes equations, as shown below: ,in, It is the fluid density. It is the fluid velocity. For time; ,in, It's pressure. It is viscous force. To combine external forces, It is an inertial force; The resultant external force The formula is: ,in, For surface tension, For gravity, It is an electrostatic volume force; The electrostatic volume force The divergence of the Maxwell stress tensor is calculated using the following formula: ,in, For a tensor, the following formula is satisfied: ,in, For electric field strength, For electric flux density, It is the identity matrix. As a constant, in a two-dimensional simulation model, the tensor The matrix expression is: ,in, The dielectric constant of free space, The relative permittivity, The electric field intensity is represented by the horizontal axis of the two-dimensional model. The electric field intensity is represented by the vertical axis of the two-dimensional model. The electrostatic volume force The calculation formula is: ; This method includes setting the grid mobility. The mesh mobility The formula is as follows: ,in The maximum speed at which the colored ink moves. is the surface tension coefficient.

2. A pixel simulation modeling method for an electrowetting display device, characterized in that... The optimization method described in claim 1 comprises the following steps: S1. Establish a geometric model: Select and establish a two-dimensional model for the colored inks; S2. Introducing material properties of the solution domain: Add materials from the COMSOL simulation software material library, including colored ink, polar liquid, pixel wall, substrate thickness, indium tin oxide electrode and hydrophobic insulating layer. The size of the colored ink is 6*130um, the size of the polar liquid is 42*160um, the size of the pixel wall is 8*15um, and the substrate thickness is 2*160um. Within a discrete individual pixel unit, the colored ink, polar liquid, indium tin oxide electrode and hydrophobic insulating layer form a stack structure. S3. Define the control function: Use continuity equations and Navier-Stokes equations to optimize and adjust the simulation model; S4. Set boundary conditions: Select a physics field and add coupling between laminar flow field, phase field, and electrostatic field. The laminar flow field and phase field jointly regulate the velocity and deformation of the liquid motion, while the electrostatic field provides the electric field for the change in contact angle. Mesh mobility is used. ; S5. Plan the mesh generation: Select a low-density mesh shape; S6. Solution Model: Select a computational model and an iterative solution algorithm for the solution; S7. Generate Report Results: Generate a two-dimensional plot group, export the report, and export the setup process and results as a PDF document.

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