• Title/Summary/Keyword: molecular alignment

Search Result 278, Processing Time 0.026 seconds

The Molecular Alignment Technology on Liquid Crystal Display (액정 디스플레이 소자의 분자배향기술)

  • 서대식
    • Electrical & Electronic Materials
    • /
    • v.10 no.1
    • /
    • pp.68-75
    • /
    • 1997
  • 본 해설에서는 평판 디스플레이 소자중의 하나인 LCD의 액정배향기술에 관하여 해설하였다. 액정배향은 LCD의 전기광학특성을 좌우하는 매우 중요한 기술이다. LCD 소자에 있어서 기판의 표면 위에 액정분자를 배열시키는 기술은 현재 러빙법이 주로 사용되고 있지만 러빙을 하지 않는 넌러빙법을 이용한 액정배향기술이 강하게 요구되고 있으며 향후 LCD에 있어서 보다 중요한 역할을 할 것으로 기대되고 있으며 고성능 LCD의 실현에는 필수 불가결한 기술로 생각된다.

  • PDF

A Simple Method for the Monitoring of Photo-induced Alignment of the Azobenzene Molecules in a Poly(malonic ester)

  • Shin, H.D.;Hwang, U.J.;Oh, C.H.;Song, S.H.;Kim, P.S.;Han, Y.K.
    • Journal of Korean Vacuum Science & Technology
    • /
    • v.6 no.1
    • /
    • pp.1-4
    • /
    • 2002
  • A simple method for real-time monitoring the molecular orientation in a polymeric film was suggested. This method was examined in the polarization holograms by two recording beams on a poly(malonic ester) containing disperse red 1. The spatial distributions of the photo-induced alignment were measured and analyzed at various polarization states of two recording beams. As the result, the directions of molecular alignments could be identified easily by our method.

  • PDF

Precise Measurement of Ultra Small Retardation of Rubbed Polyimide Alignment Layer Using an Improved Transmission Ellipsometer (개선된 투과형 타원계를 사용한 러빙된 Polyimide 배향막의 초미세 위상지연 정밀 측정)

  • Lyum, Kyoung Hun;Park, Sang Uk;Yang, Seong Mo;Yoon, Hee Kyu;Kim, Sang Youl
    • Korean Journal of Optics and Photonics
    • /
    • v.24 no.2
    • /
    • pp.77-85
    • /
    • 2013
  • The precision of retardation measurement has been improved upto $3{\sigma}$ <0.005 nm after improvements are made to the conventional transmission ellipsometer. Improvements are made such that, i) the polarizer module instead of the sample stage is rotated, ii) the light source is replaced, iii) the starting points of two rotating modules are accurately synchronized, and iv) the fine background retardation is compensated. Together with the newly introduced RVD (Retardation Vector Difference) method, the improved instrument is successfully applied to characterize the ultra small optical birefringence of the rubbed polyimide alignment layer, after the residual retardation due to glass substrate whose magnitude is about 1.0 nm is properly subtracted. It is verified that the net retardation of the alignment layer ranges from 0.05 nm to 0.15 nm.

The Alignment of Liquid Crystals on the Film Surfaces of Soluble Aromatic Polyimides Bearing t-Butylphenyl and Trimethylsilylphenyl Side Groups

  • Hahm, Suk-Gyu;Jin, Kyeong-Sik;Park, Sam-Dae;Ree, Moon-Hor;Kim, Hyung-Sun;Kwon, Soon-Ki;Kim, Yun-Hi
    • Macromolecular Research
    • /
    • v.17 no.12
    • /
    • pp.976-986
    • /
    • 2009
  • With the study goal of firstly elucidating the anisotropic interactions between oriented polymer chain segments and liquid crystal (LC) molecules, and secondly of determining the contributions of the chemical components of the polymer segments to the film surface topography, LC alignment, pretilt, and anchoring energy, we synthesized three dianhydrides, 1,4-bis(4'-t-butylphenyl)pyromellitic dianhydride (BBPD), 1,4-bis(4'-trimethylsilylphenyl)pyromellitic dianhydride(BTPD), and 2,2'-bis(4"-tert-butylphenyl)-4,4',5,5'-biphenyltetracarboxylic dianhydride (BBBPAn), and a series of their organosoluble polyirnides, BBPD-ODA, BBPD-MDA, BBPD-FDA, BTPD-FDA, and BBBPAn-FDA, which contain the diamines 4,4'-oxydianiline (ODA), 4,4'-methylenediamine (MDA), and 4,4'-(hexafluoroisopropylidene)dianiline (FDA). All the polyimides were determined to be positive birefringent polymers, regardless of the chemical components. Although all the rubbed polyimide films exhibited microgrooves which were created by rubbing process, the film surface topography varied depending on the polyimides. In all the rubbed films, the polymer chains were unidirectionally oriented along the rubbing direction. However, the degree of in-plane birefringence in the rubbed film varied depending on the polyimides. The rubbing-aligned polymer chains in the polyimide films effectively induced the alignment of nematic LCs along their orientation directors by anisotropic interactions between the preferentially oriented polymer chain segments and the LCs. The azimuthal and polar anchoring energies of the LCs ranged from $0.45{\times}10^{-4}\;-\;1.37{\times}10^{-4}\;J/m^2$ and from $0.86{\times}10^{-5}\;-\;4.26{\times}10^{-5}\;J/m^2$, respectively, depending on the polyimides. The pretilt angles of the LCs were in the range $0.10-0.62^{\circ}$. In summary, the soluble aromatic polyimides reported here are promising LC alignment layer candidates for the production of advanced LC display devices.

Unusual Alignment of Liquid Crystals on Rubbed Films of Polyimides with Fluorenyl Side Groups

  • Hahm, Suk-Gyu;Lee, Taek-Joon;Chang, Tai-Hyun;Jung, Jin-Chul;Zin, Wang-Cheol;Ree, Moon-Hor
    • Proceedings of the Polymer Society of Korea Conference
    • /
    • 2006.10a
    • /
    • pp.239-239
    • /
    • 2006
  • In the present study, we synthesized CBDA-FDA and its analogue, poly(4,4' -(9,9-fluorenyl)diphenylene pyromellitimide) (PMDA-FDA), and then investigated quantitatively the orientational distributions of the polymer chain segments in the surfaces of their films by using linearly polarized Fourier transform infrared (FTIR) spectroscopy and optical retardation analysis. We also examined the films' surface topographies using high spatial resolution atomic force microscopy (AFM). Further, rubbed films were used to assemble antiparallel and $90^{\circ}-twisted$ nematic (TN) LC cells, and the alignment behaviors, pretilt angles and anchoring energies of the LC molecules in the cells were determined. The films were found to have very interesting surface morphologies and LC alignment behaviors, which have not previously been reported. The observed LC alignments, pretilt angles and anchoring energies are discussed by taking into account the interactions of the LC molecules with the oriented polymer chain segments and the surface morphologies.

  • PDF

A Heuristic Algorithm to Find All Normalized Local Alignments Above Threshold

  • Kim, Sangtae;Sim, Jeong Seop;Park, Heejin;Park, Kunsoo;Park, Hyunseok;Seo, Jeong-Sun
    • Genomics & Informatics
    • /
    • v.1 no.1
    • /
    • pp.25-31
    • /
    • 2003
  • Local alignment is an important task in molecular biology to see if two sequences contain regions that are similar. The most popular approach to local alignment is the use of dynamic programming due to Smith and Waterman, but the alignment reported by the Smith-Waterman algorithm has some undesirable properties. The recent approach to fix these problems is to use the notion of normalized scores for local alignments by Arslan, Egecioglu and Pevzner. In this paper we consider the problem of finding all local alignments whose normalized scores are above a given threshold, and present a fast heuristic algorithm. Our algorithm is 180-330 times faster than Arslan et al.'s for sequences of length about 120 kbp and about 40-50 times faster for sequences of length about 30 kbp.

Liquid Crystal Alignment and Generation of Pretilt Angle by Using Photo-alignment Techniques on Different Polymer Moleculars (광배향기술을 이용한 액정배향의 기구 및 폴리이미드의 분자구조가 프리틸트각에 미치는 영향)

  • 황율연;이창훈;박지호;서대식
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • 1997.11a
    • /
    • pp.112-115
    • /
    • 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.

  • PDF

A DNA Sequence Alignment Algorithm Using Quality Information and a Fuzzy Inference Method (품질 정보와 퍼지 추론 기법을 이용한 DNA 염기 서열 배치 알고리즘)

  • Kim, Kwang-Baek
    • Journal of Intelligence and Information Systems
    • /
    • v.13 no.2
    • /
    • pp.55-68
    • /
    • 2007
  • DNA sequence alignment algorithms in computational molecular biology have been improved by diverse methods. In this paper, we proposed a DNA sequence alignment algorithm utilizing quality information and a fuzzy inference method utilizing characteristics of DNA sequence fragments and a fuzzy logic system in order to improve conventional DNA sequence alignment methods using DNA sequence quality information. In conventional algorithms, DNA sequence alignment scores were calculated by the global sequence alignment algorithm proposed by Needleman-Wunsch applying quality information of each DNA fragment. However, there may be errors in the process for calculating DNA sequence alignment scores in case of low quality of DNA fragment tips, because overall DNA sequence quality information are used. In the proposed method, exact DNA sequence alignment can be achieved in spite of low quality of DNA fragment tips by improvement of conventional algorithms using quality information. And also, mapping score parameters used to calculate DNA sequence alignment scores, are dynamically adjusted by the fuzzy logic system utilizing lengths of DNA fragments and frequencies of low quality DNA bases in the fragments. From the experiments by applying real genome data of NCBI (National Center for Biotechnology Information), we could see that the proposed method was more efficient than conventional algorithms using quality information in DNA sequence alignment.

  • PDF

Effects of Thermal Imidization and Annealing on Liquid Crystal Alignment ever Rubbed Polyimide Layers: Change in the Pretilt Angle

  • Paek, Sang-Hyon
    • Macromolecular Research
    • /
    • v.9 no.6
    • /
    • pp.303-312
    • /
    • 2001
  • The fabrication of liquid crystal display (LCD) panels involves several thermal processes such as imidization of the alignment layer (AL) and annealing of the rubbed polyimide AL. The nature of these processes on the LC alignment, especially on the pretilt angle (Θ$\_$p/) has been systematically studied, employing various types of polyimide structures. The imidization effect depends on the nature of polyimid precursors; Θ$\^$p/ increases with the degree of the imidization for the main-chain type of ALs, due to the decrease in the surface polarity, but this relation is not applicable to the alkylated ones in which the steric effect at the AL surface by the aliphatic side chains is dominant. Annealing of the rubbed polyimide AL deteriorates its rubbing-induced molecular orientation and subsequently the overlying LC alignment, resulting in the decrease in Θ$\_$p/. Especially, annealing of the LC cell affects the LC-AL interaction as well as the AL orientation and thus its effect on LC alignment depends sensitively on the nature of LC-polyimide interface; aromatic moiety in the polyimide structure gives better thermal stability of LC alignment while fluorinated polyimide ALs induce the less stable alignment.

  • PDF