화학공학소재연구정보센터
홈 로그인 로그아웃 연락처 사이트맵
Journal of the Korean Industrial and Engineering Chemistry, Vol.12, No.6, 595-609, October, 2001
Export Citation
고성능 LCD를 위한 광배향과 셀 모드
Photoalignments and Cell Modes for High Performance LCDs
김현욱, 김종득†
  • 한국과학기술원 화학공학과, 대전
Hyun Wuk Kim, and Jong Duk Kim†
  • Department of Chemical Engineering, Korea Advanced Institute of Science and Technology, Daejeon, Korea
E-mail:
초록
LCD 패널산업이 성숙기에 접어들고 있지만 액정배향의 문제를 만족스럽게 해결하지 못하고 있다. 액정 배향기술로서 전통적인 러빙법에 이어 광배향법이 주목을 받고 있으며 액정패널의 새로운 모드가 소개되고 있다. 광배향은 광민감성을 갖는 분자단의 이성체 구조를 이용하거나 폴리이미드를 부분 광분해하는 방법, 그리고 시나메이트나 쿠마린과 같은 광활성 분자단을 갖는 물질을 부분적으로 다량체화하는 방법, 광흡수에너지로 회절무늬를 만들어(SRG) 표면구조를 바꾸어주면 액정배향과 표면특성이 바뀌어 진다. 배향기구는 표면구조, 표면에너지에 의한 복합적인 것으로 인식되고 있으며 전경사각(pretilt angle), 고정에너지(anchoring energy) 등의 셀 내에서의 파라미터를 조정하는 것이 중요하다. 이러한 조정을 통하여 액정배열을 조정할 수 있으며 배열상태에 따라서 시야각이 넓고 반응시간을 조정할 수 있는 새로운 동작모드가 개발되고 있다. 본 총설은 액정의 광배향과 배열모드를 소개하여 액정패널의 신기술 개발에 기여하고자 한다.
Alignments of liquid crystals in LCD panel industries are of classical research issues, but there are no reliable technologies available as to date, except for the rubbing process that are used in the commercial applications. This review will focus on recent progresses made in photoalignment and alignment structure of cells. Photoalignment utilize polarized light to modify the surface structure of materials, which can be categorized to photoisomerization, photodegradation, photodimerization and/or surface relief grating. Photoisomerization uses the cis/trans transition of isomers of azo-compounds; photodegradation degrades the polyimide film by shining polarized light; photodimerization usually cyclize the neighboring double bonds with cinnamates or cumarine group; and surface relief grating forms surface fringes on the film of azo-compounds. All these methods can control the alignment states of liquid crystals, governed by pretilt angles and anchoring energies of liquid crystals on the surfaces. In addition, some of the recently proposed cell modes for a wide viewing angle and a fast response are also introduced.
Keywords:photoalignment;photoisomerization;photodimerization;photodegradation;surface relif grating;wide viewing angle
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