• Bulletin of the Korean Chemical Society
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• 제33권8호
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• pp.2806-2808
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• 2012

• 한국전기전자재료학회논문지
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• 제18권11호
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• pp.1028-1032
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• 2005

Liquid crystal (LC) alignment using a photoalignment method by irradiation of polarized ultraviolet (UV) on an alignment layer has been investigated. Photoalignment method exhibits weaker anchoring energy than rubbing method so that we have studied electro-optic characteristics of fringe-field switching (FFS) mode with alignment layers using the photo and rubbing alignment methods. The cell using photo alignment layer shows lower threshold and operation voltage than those using rubbed alignment layer. Also, the former method shows higher transmittance than that of the latter.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 춘계학술대회 논문집
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• pp.259-262
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• 1998

The liquid crystal (LC) alignment and pretilt angle generation using photo-alignment method were investigated in this study. We obtained that the monodomain alignment of nematic(N) LC increases with increasing irradiation time in a cell with linearly polarized ultraviolet (LPUV) light irradiation on polyimide (Pl) surfaces. We consider that the monodomain alignment is able to be anisotropic dispersion force due to photo-depolymerization of polymer with LPUV light irradiation on Pl surface. Also, we observed that the uniform alignment of NLC is obtained in a cell with normally LPUV light irradiated on Pl surface at 30 min. and then oblique LPUV is secondly irradiated on Pl surfaces rotated by 90$^{\circ}$. The pretilt angle of NLC is generated about 1.5$^{\circ}$ with oblique angle 60$^{\circ}$.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 춘계학술대회 논문집 디스플레이 광소자 분야
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• pp.118-122
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• 2005

Liquid crystal (LC) alignment using a photoalignment method by irradiation of polarized ultraviolet (UV) on an alignment layer has been investigated. Photoalignment method exhibits weaker anchoring energy than rubbing method so that we have studied electro-optic characteristics of fringe-field switching (FFS) mode with alignment layers using the photo and rubbing alignment methods. The cell using photo alignment layer shows lower threshold and operation voltage than those using rubbed alignment layer. Also. the former method shows higher transmittance than that of the latter.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 춘계학술대회 논문집 디스플레이 광소자 분야
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• pp.181-184
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• 2000

A new photo-alignment material, copoly (PM4Ch-ChMA), copoly (poly (4-methacryloyloxy) chalcone-chalconemethacryl) was synthesized and the electro-optical (EO) characteristics for the photo-aligned vertically aligned (VA)-LC display (LCD) were investigated. The monodomain alignment of the NLC for the photo-aligned VA-LCD by linearly polarized UV exposure on the photo-dimerized copoly (PM4Ch-ChMA) surfaces was observed. Excellent voltage-transmittance characteristics for the photo-aligned VA-LCD by UV exposure for 1 min. on the copoly (PM4Ch-ChMA) surfaces were achieved. The response time of the photo-aligned VA-LCD by UV exposure on for 1 min. the copoly (PM4Ch-ChMA) surfaces was about 39.3 ms. The response time for the photo-aligned VA-LCD decreased with increasing UV exposure time.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 D
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• pp.1261-1263
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• 1998

In this paper, we obtained that the monodomain alignment of nematic liquid crystal (NLC) increases with increasing irradiation time with linearly polarized ultraviolet (LPUV) light irradiation on polyimide (PI) surfaces. It was found that the monodomain alignment of NLC is obtained in a cell with normally LPUV light irradiated on PI surface at 30 min. and then oblique LPUV is secondly irradiated on PI surfaces rotated by $90^{\circ}$. The pretilt angle of NLC is generated about $2.5^{\circ}$ with oblique angle of $60^{\circ}$ and then decreased with increasing the oblique angle of IN light irradiation. It is considered that the pretilt angle of NLC is attributed to the photo-depolymerization of polymer with the oblique angle of UV light. The voltage-transmittance and response time characteristics of photo-aligned twisted nematic (TN)-LCD with UV light irradiation time of 60 min. were almost same in comparison with rubbing treated TN-LCD.

• 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.

• 한국전기전자재료학회논문지
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• 제11권6호
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• pp.477-480
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• 1998

In this paper, we investigated the liquid crystal(LC) alignment and generation of pretilt angle by using photo-alignment techniques on two kinds of polyimide(PI) surface, It was found that the uniform alignment for nematic(N) LC is obtained in a cell with slanted UV light irradiation on PI surface without side chain. We successfully observed that the pretilt angle of NLC is generated about $3^{\circ}$ with an incident angle of 70 degree on the PI surface without side chain. It is considered that the pretilt angle generation in NLC is attributed to interaction between the LC molecules and the polymer surfaces.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 추계학술대회 논문집
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• pp.112-115
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• 1997

In this paper, we investigated the liquid crystal(LC) alignment and generation of pretilt angle by using photo-alignment techniques on two kinds of polyimide(Pl) surface. It was found that the uniform alignment for nematic(N) LC is obtained in a cell with slanted UV light irradiation on PI surface without side-chain. We successfully observed that the pretilt angle of NLC is generated about 3.3 degrees in a cell with an incidence angle of 70 degrees on PI surface without side chain. It is considered that the pretilt angle generation in NLC is attributed to interaction between the LC molecular and the polymer.

• 폴리머
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• 제26권2호
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• pp.209-217
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• 2002

편광 푸리에 변환 적외선 분광법과 자외선 분광법을 이용하여 액정 display (LCD)의 배향막으로 널리 사용되는 폴리이미드 (PI) 필름의 편광 자외선 (PUV) 조사에 따른 액정의 배향 메카니즘을 연구하였다. UV 측정 결과, PI 필름은 360 nm 이하 파장의 자외선을 주로 흡수하여 광화학 반응이 유도됨을 알 수 있었다. 또한, PUV가 조사된 PI의 경우, PI 분자들의 분해로 인해 FT-IR 흡수 피크들의 강도가 조사시간에 따라 감소하였고, $3244 cm^{-1}$ 부근에서 완만한 곡선 형태의 새로운 피크가 형성되었다. 또한 조사된 PUV의 극성 방향에 평행한 PI 분자들의 우선적인 광분해 반응으로 인하여 PUV 조사 후 남아 있는 PI 분자들은 조사된 PUV 극성 방향과 수직 배향을 나타내었다. 하지만 러빙 처리된 PI 필름은 러빙 방향과 평행하게 PI 분자들의 재배향이 유도됨을 확인하였다. 또한 러빙 처리 및 PUV가 조사된 PI 배향막을 차용하여 제조된 액정 셀에서는 액정이 러빙 방향에 대해서는 평행하게, 조사된 PUV의 극성방향과는 수직으로 배향함을 확인하였다.