2002 Fiscal Year Final Research Report Summary
Development of a software for predicting injection flow of liquid crystal for the purpose of reducing the cost of liquid crystal display
| Project/Area Number |
13650200
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Fluid engineering
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| Research Institution | Kochi University of Technology |
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Principal Investigator |
CHONO Shigeomi Kochi University of Technology, Department of Mechanical Engineering, Professor, 工学部, 教授 (20155328)
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| Co-Investigator(Kenkyū-buntansha) |
TSUJI Tomohiro Kochi University of Technology, Department of Mechanical Engineering, Associate Professor, 工学部, 助教授 (60309721)
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| Project Period (FY) |
2001 – 2002
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| Keywords | Liquid Crystal / Liquid Crystal Display / Injection of Liquid Crystal / Fluid Mechanics / Hele-Shaw Flow / Numerical Analysis / Development of a Software |
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| Research Abstract |
Injection process is one of the most important processes for manufacturing liquid crystal displays (LCD). The purpose of this research project is to develop a widely used software which can predict numerically the injection process. Such the software makes possible to reduce greatly the injection time for LCD with arbitrary size and shape, leading to high productivity and to a decrease in cost.
The Leslie-Ericksen equation was selected as a constitutive equation for liquid crystalline flow, and the Hele-Shaw approximation was made for both the equation of motion and the constitutive equation. Finite difference method was employed to discretize the governing differential equations. In this study, we have taken into account the effects of surface tension of liquid crystals and variation in cell gap during injection process. Concerning the surface tension, it was assumed that the shape of a meniscus was uniform throughout the free surface and that a contact angle was so small that we could put it to be zero. As a result, it is concluded that the effect of the surface tension can be expressed as an additional pressure difference Δ p=2γ/h (γ : surface tension, h : cell gap), which is the driving force of the injection process. Concerning the variation in cell gap, we computed the local cell gap at every time step by using both the pressure distribution in the cell and the elasticity of spacers with resort to the Hertz formula in the field of mechanics of materials.
In parallel with developing the software, we made an experiment for injection process. Using a liquid crystal cell with 75mm×100mm×4.5μm in size, we took photographs of the positions of a free face at every moment during the injection process. The agreement of the experimental data with the computational results obtained with using the software developed was satisfactory.
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