• Title/Summary/Keyword: homeotropic

Search Result 103, Processing Time 0.032 seconds

LC Aligning Capabilities of a Nematic Liquid Crystal on Homeotropic Polyimide Surface by New Ion-beam Irradiation

  • Ok, Chul-Ho;Kang, Dong-Hun;Lee, Kang-Min;Han, Jin-Woo;Kim, Byoung-Yong;Oh, Byeong-Yun;Kim, Young-Hwan;Hwang, Jeong-Yeon;Lee, Sang-Keuk;Han, Jeong-Min;Seo, Dae-Shik
    • Transactions on Electrical and Electronic Materials
    • /
    • v.8 no.6
    • /
    • pp.265-267
    • /
    • 2007
  • The liquid crystal(LC) aligning capabilities of a nematic liquid crystal(NLC) on a homeotropic polyimide(PI) surface using a new ion-beam method were studied. Exposure ion-beam of $45^{\circ}$ incidence angle shows a good LC alignment of the NLC on the homeotropic PI surface. Also, on the homeotropic PI surface, the tilt angle of the NLC by exposure ion-beam of $45^{\circ}$ incidence angle had a tendency to decrease as increased ion-beam energy density. And, on the homeotropic PI surface, the alignment character of the NLC with respect to ion-beam energy was good at 1500 eV. And we achieved satisfactory result for EO character.

Vertical Alignment of Liquid Crystal by Ion Beam Irradiation (이온빔 배향에 의한 수직 배향막의 액정 배향)

  • Kang, Dong-Hoon;Kim, Byoung-Yong;Kim, Young-Hwan;Ok, Chul-Ho;Han, Jeong-Min;Kim, Jong-Hwan;Lee, Sang-Keuk;Seo, Dae-Shik
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • 2007.06a
    • /
    • pp.414-414
    • /
    • 2007
  • In this study, Liquid Crystal (LC) alignment and tilt angle generation in Nematic Liquid Crystal (NLC) with negative dielectric anisotropy on the homeotropic PI surface with new ion beam exposure are reported. Also. high density of ion beam energy (DuoPIGatron type Ar ion gun) is used in this study. The tilt angle of NLC on the homeotropic Polyimide (PI) surface for all incident angles is measured about 38 degree and this has a stabilization trend. And the good LC alignment of NLC on the PI surface with ion beam exposure of $45^{\circ}$ incident angle was observed. Also the tilt angle of NLC on the homeotropic PI surface with ion beam exposure of $45^{\circ}$ had a tendency to decrease as ion beam energy density increase. The tilt angle could be controlled from verticality to horizontality. Also, the LC aligning capabilities of NLC on the homeotropic PI surface according to ion beam energy has the goodness in case of more than 1500 eV. Finally. the superior LC alignment thermal stability on the homeotropic PI surface with ion beam exposure can be achieved. For OCB(Optically Compensated Bend) mode driving, we can need pretilt angles control for fast response time. In this study, We success pretilt angles control. Consequently, this result can be applied for OCB mode.

  • PDF

Study on the LC Alignment on Vertical Alignment Polymer Surface using the AFM (AFM을 이용한 수직배향막 폴리머 표면위의 액정배향에 관한 연구)

  • 김완철;송선애;전일철;이종문;이승희
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.16 no.6
    • /
    • pp.510-514
    • /
    • 2003
  • We have studied the alignment of liquid crystals (LCs) on homeotropic polymeric surface that is scanned using an atomic force microscope (AFM) tip by optical polarizing microscopy and computer simulation. The scanned areas on one substrate are 5 $\mu\textrm{m}$ ${\times}$ 5 $\mu\textrm{m}$, 10 $\mu\textrm{m}$ ${\times}$ 10 $\mu\textrm{m}$, and 20 $\mu\textrm{m}$ ${\times}$ 20 $\mu\textrm{m}$ and this substrate is assembled to another substrate coated. with homeotropic polymer. The fabricated micro-LC cell using two substrates does not show any hysteresis and disclination lines inside the nano-rubbing areas, while changing voltage up and down. This indicates that the pretilt angle exists in the areas, thereby forming a hybrid LC configuration. From the experimental and computer simulation results, we can understand that the AFM rubbing clearly changes surface status of homeotropic alignment layer and causes the pretilt angle to an initial scanning direction.

Control of Tilt Angle in the Nematic Liquid Crystal on the Homeotropic Polyimide Surface as a Function of the Baking Condition (소성 조건 변화에 따른 수직 폴리이미드 표면에서 이용한 네마틱 액정의 틸트 제어)

  • Hwang, Jeoung-Yeon;Lee, Kyung-Jun;Kim, Kang-Woo;Seo, Dae-Shik
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.17 no.6
    • /
    • pp.661-667
    • /
    • 2004
  • The control of tilt angle for nematic liquid crystal (NLC) with negative and positive dielectric anisotropy on the rubbed homeotropic polyimide (PI) using baking method by hot plate equipment was investigated. LC tilt angle decreased with increasing baking temperature and time. Especially, the low LC tilt angle of positive type NLC (Δ$\varepsilon$>0) on the rubbed homeotropic PI surface by increasing temperature and time was measured. The tilt angle of positive type NLC(Δ$\varepsilon$>0) is smaller than that of the negative type (Δ$\varepsilon$>0) on rubbed PI with increasing baking temperature and time. We consider that the tilt angle of NLC is decreased due to increasing the steric interaction between horizon component of permittivity $\varepsilon$ = of NLC and the stress of polymer side chain by high temperature. As the increase of baking temperature, we obtain that AFM (atomic force microscope) image of rubbed PI surface using Hot-plate method has formed better solid micro-groove structure than oven method.

Characteristic Analysis of Vertical Alignment by Ion-beam Irradiation Angle and Energy Density (이온빔 조사 각도와 에너지강도에 의한 수직 배향막의 특성 분석)

  • Kang, Dong-Hun;Oh, Byeong-Yun;Kim, Byoung-Yong;Han, Jin-Woo;Kim, Young-Hwan;Ok, Chul-Ho;Han, Jeong-Min;Lee, Sang-Keuk;Seo, Dae-Shik
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • 2007.11a
    • /
    • pp.398-398
    • /
    • 2007
  • The Liquid Crystal (LC) alignment uniformity is very important in LC devices. The alignment mechanism of LC molecules on a rubbed polyimide (PI) surface is very important for both LC fundamental research and application. So, Generally a rubbing method to align LC has been widely used to mass-produce LCD panels. But because rubbing method is contact method between rubbing fabric and indium-tin-oxide glass or flexible substrate, rubbing method has some defects, such as the electrode charges and the creation of contaminating particles. Thus we strongly recommend a non-contact alignment technique for getting rid of some defects of rubbing method. Most recently, the LC aligning capabilities achieved by ion-beam exposure on the organic and nonorganic thin film surface have been reported successfully. In this research, we studied the tilt angle generation and electro-optical performances for a NLC on homeotropic polyimide surfaces with ion-beam exposure. The LC aligning capabilities of a nematic liquid crystal (NLC) on a homeotropic PI surface using a new ion-beam method were studied. On the homeotropic PI surface, the tilt angle of the NLC by exposure ion-beam had a tendency to decrease as increased ion-beam energy density. And, on the homeotropic PI surface, the alignment character of the NLC with respect to ion-beam energy was good. And we achieved satisfactory result for EO character.

  • PDF

Homeotropic Alignment Effect for Nematic Liquid Crystal on the $SiO_x$ Thin Film Layer by New Ion beam Exposure (새로운 이온빔을 이용한 $SiO_x$ 박막 표면의 액정 배향 효과)

  • Choi, Sung-Ho;Kim, Byoung-Yong;Han, Jin-Woo;Oh, Yong-Cheul;Seo, Dae-Shik
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • 2006.11a
    • /
    • pp.311-312
    • /
    • 2006
  • We studied homeotropic alignment effect for a nematic liquid crystal (NLC) on the $SiO_x$, thin film irradiated by the new ion beam method $SiO_x$ thin films were deposited by plasma enhanced chemical vapor deposition (PECVD) and were treated by the DuoPIGatron ion source. A uniform liquid crystal alignment effect was achieved over 2100 eV ion beam energy. Tilt angle were about $90^{\circ}$ and were not affected by various ion beam energy.

  • PDF

EO Characteristics of the Mew MVA-LCD using a Crossed Stripe Grating-Groove Vertical Alignment (CGVA) Layer

  • Lee, Kyung-Jun;Hwang, Jeoung-Yeon;Lee, Sang-Keuk;Seo, Dae-Shik
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • 2003.07b
    • /
    • pp.999-1002
    • /
    • 2003
  • Electrooptical (EO) characteristics of a new multidomain vertical-alignment (MVA) liquid crystal display (LCD) with negative dielectric anisotropy on a homeotropic photopolymer were studied. Good voltage-transmittance (V-T) curves of the new MVA-LCD on the homeotropic photopolymer were obtained. Also, the stable response time of the new MVA-LCD on the homeotropic photopolymer was achieved. The viewing angle of the new MVA-LCD could be improved by a crossed stripe grating-groove surface as the alignment layer using a photolithograph method on the photopolymer.

  • PDF

Locked Super Homeotropic (LSH) liquid crystal device for large size LCD (대면적의 LCD를 위한 갇혀진 Locked Super Homeotropic (LSH) 액정 디바이스)

  • Park, S.H.;Song, I.S.;Kim, W.C.;Oh, S.T.;Lee, S.H.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • 2004.05a
    • /
    • pp.146-149
    • /
    • 2004
  • We have studied a liquid crystal (LC) mode (named locked super homeotropic (LSH)) in which the LCs aligned homeotropically are locked by surrounding walls such as cubic, hexagonal and cylinder. In the device, the vertically aligned LCs tilt down symmetrically around the center of the cell when a voltage is applied and thus it exhibits wide viewing angle. The structure of this LSH mode is suitable for large-sized display panels. since the LCs are locked in micro domains the LCs do not flow to the bottom of the panel by gravity. This mode is applicable to achieve high performance TFT-LCD TV because of high performance characteristics such as high contrast, high brightness, wide-viewing angle.

  • PDF

Synthesis and Properties of Novel Homeotropic Alignment Materials with Long Side Chain

  • Han, B.R.;Kim, Y.B.
    • 한국정보디스플레이학회:학술대회논문집
    • /
    • 2002.08a
    • /
    • pp.475-478
    • /
    • 2002
  • VA-LCDs is widely used for recent LCD productions owing to good viewing angle and high contrast. To apply for VA-LCDs, we have synthesized novel homeotropic alignment materials, which all generated high pretilt angles ($9^{\circ}$). The thermal stabilities of them were observed by thermogravimetric analysis (TGA). Transmittances of the NLC cell used the new alignment material were not changed before and after thermal annealing at $120^{\circ}C$ for 24hrs. In this work, the synthesis and alignment properties of new homeotropic alignment materials will be reported.

  • PDF