• Transactions on Electrical and Electronic Materials
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• 제7권3호
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• pp.145-148
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• 2006

In this study, the response surface modeling of the pretilt angle control using in-situ photoalignment method with oblique UV exposure .on plastic substrate is investigated. The pretilt angle is the main factor to determine the alignment of the liquid crystal display. The response surface model is used to analyze the variation of the pretilt angle on the various process conditions. Heating temperature and UV exposure time are considered as input factors. The liquid crystal (LC) pretilt angle increased with increasing heating temperature and UV exposure time. The analysis of variance is used to analyze the statistical significance and the effect plots are also investigated to examine the relationship between the process parameters and the response.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집
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• pp.337-340
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• 2001

The control of high pretilt angle for nematic liquid crystal (NLC) with negative dielectric anisotropy on the rubbed blending polyimide (homeotropic and homogeneous alignment) surface were studied. High NLC pretilt angle generated on the blending polyimide (homeotropic polyimide and SE-7492 surface was measured and the NLC pretilt angle increases with blending ratio and rubbing strength. However, the NLC pretilt angle generated on the blending polyimide (homeotropic polyimide and SE-150 surface was not varied. The high pretilt angle the NLC using blending polyimide surface can be achieved.

• 한국전기전자재료학회논문지
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• 제12권1호
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• pp.75-80
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• 1999

In this study, we have investigated the relationship between the generation of pretilt angle and the polarization component in cells with UV light irradiation on polyimide (PI) surface. It was found that the generated pretilt angle is about $1.4^{\circ}$ with S-polarized UV light irradiation of $75^{\circ}$ on PI surface; it may be attributed to the asymmetry triangular of polymer surface with oblique S-polarized UV light irradiation on PI surface. Also, we measured that the generated pretilt angle is about $2.0^{\circ}$ with oblique P polarized UV light irradiation of $75^{\circ}$ on PI surface. Consequently, we suggest that the generated pretilt angle of the NLC is attributed to the interaction between the LC molecules and the polymer surface with oblique polarized UV light irradiation on PI surface.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.559-562
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• 2003

The effect of pretilt angle on viewing characteristics of an IPS cell is discussed. We calculated optical viewing angle in the IPS cell as function of pretilt angle from $0.5^{\circ}$ to $4^{\circ}$, so that we could confirm that low pretilt angle was profitable for wider viewing property. In order to verify the calculation, we made an IPS cell with very low pretilt angle by the alignment method using ion beam exposure. In the experiment, we confirmed that wider viewing characteristics can be achieved if lower pretilt angle was applied in IPS mode. And Ion beam alignment method was useful for low pretilt creation.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 디스플레이 광소자분야
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• pp.81-83
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• 2003

We have investigated the generation of pretilt angle for a nematic liquid crystal (NLC) alignment with rubbing alignment method on polyimide surfaces using thin plastic substrates. It was found that monodomain alignment of LNC is obtained with rubbing alignment method on polyimide surfaces using thin plastic substrates. The generated NLC pretilt angles are about $3^{\circ}$ by the rubbing alignment method on thin plastic substrates, However, the pretilt angle measured at about $1.7^{\circ}$ lower on the glass substrate than by thin plastic substrate. It is considered that this alignment may be attributed to roughness of micro groove substrate. The tilt angle increases with increasing baking temperature for making polyimide layer using glass substrate. It was concluded that pretilt angle in the polyimide surface is attributable to the increasing of imide rato.

• 한국전기전자재료학회논문지
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• 제13권1호
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• pp.75-79
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• 2000

In this study, we investigated the pretilt angle generation and liquid crystal (LC) alignment by ultravi-olet (UV) light irradiation during imidization of polymide. The generated pretilt angle of nematic (N) LC by using the in-situ photo-alignment method was smaller than that of the conventional UV photo-alignment method. Also, generated pretilt angle of NLC tends to increase by annealing. In case of using the polymer(AL-3046), we found that the in-situ Uv photo-alignment method has higher thermal stability of LC alignment, but it has a disadvantage to control pretilt angle.

• 한국전기전자재료학회논문지
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• 제14권4호
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• pp.336-340
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• 2001

We have investigated the generation of pretilt angle and alignment stability for a nematic liquid crystal (NLC) with obliquely polarized UV exposure on the three kinds of photo-polymer. High pretilt angle of the NLC was obtained by polarized UV exposure on a PM4Ch surface for 1 min. But, the low pretilt angle of he NLC on a PVCi surface was observed. The pretilt angle generated is attributed ot the photosensitivity by the long side chaining of photo-polymer. Also, a good thermal stability of the three kinds of photo-polymer were obtained by thermogravimetric analysis (TGA) measurement until 300$^{\circ}C$. Finally, the good LC aligning capabilities using the photodimerization method were observed by annealing-treatment until 150$^{\circ}C$.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.533-536
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• 1999

In this study, we investigated pretilt angle generation and liquid crystal alignment by UV light irradiation during imidization of polyimide. Generated pretilt angle of NLC by using in-situ UV photo-alignment method was smaller than that of the conventional UV photo-alignment method. Also, generated pretilt angle of NLC tends to increase by annealing. We found that in-situ UV photo-alignment method has higher thermal stability of LC alignment, but it has a disadvantage to control pretilt angle.

• 한국전기전자재료학회논문지
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• 제11권6호
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• pp.481-485
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• 1998

We investigated the generation of high pretilt angle for nematic liquid crystal (NLC) in a cell with obilique non-polarized ultraviolet (UV) light irradiation on mixtured polyimide surface. It was found that the monodomain alignment of NLC is obtained with an angle of incidence of 75∼85 degrees on PI surface. We consider that the monodomain alignment of NLC is attributed to anisotropic dispersion force effect to photo-depolymerization of polymer. We successfully observed that the pretilt angle of NLC is generated above 5 degree with an angle of incidence of 75∼85 degrees. It is considered that the pretilt angle generation NLC is attributed to interaction between the LC molecules and the polymer surfaces.

• 한국전기전자재료학회논문지
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• 제17권3호
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• pp.311-318
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• 2004

We have studied electro-optic characteristics as a function of pretilt angle ($\theta$$_{p}$) in the fringe-field switching (FFS) mode using the LC with positive dielectric anisotropy. When $\theta$$_{p}$ is increased from 0$^{\circ}$ to 20$^{\circ}$, a maximum transmittance and an operating voltage are obviously decreased. In the viewing angle characteristics, the cell with low pretilt angle has a wide region for the contrast ratio greater than 5 and has a best luminance uniformity. Therefore, in the FFS device, a low pretilt angle is favored for high transmittance and wide viewing angle.gle.