• 제목/요약/키워드: crystal alignment

검색결과 537건 처리시간 0.032초

Liquid Crystal Aligning Capabilities Treated on Organic Overcoat Thin Films by Ion Beam Irradiation Method

  • Han, Jeong-Min;Kim, Byoung-Yong;Kim, Jong-Yeon;Kim, Young-Hwan;Han, Jin-Woo;Hwang, Jeoung-Yeon;Lee, Sang-Keuk;Kang, Dong-Hun;Ok, Chul-Ho;Seo, Dae-Shik
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • 제20권3호
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    • pp.245-249
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    • 2007
  • The liquid crystal display (LCD) applications treated on the organic overcoat thin film surfaces by ion beam irradiation was successfully studied. The good LC aligning capabilities treated on the organic overcoat thin film surfaces with ion beam exposure of $60^{\circ}$ for 2 min above ion beam energy of 1200 eV can be achieved. But, the alignment of defect of NLC on the organic overcoat surface at low energy of 600 eV was measured. The pretilt angle of NLC on the organic overcoat thin film surface with ion beam exposure of $60^{\circ}$ for 2 min at energy of 1800 eV was measured about 1 degree. Finally, the good thermal stability of LC alignment on the organic overcoat thin film surface with ion beam exposure of $60^{\circ}$ for 2 min until annealing temperature of $200^{\circ}C$ can be measured.

Reduction of Gamma Distortion in Oblique Viewing Directions in Polymer-stabilized Vertical Alignment Liquid Crystal Mode

  • Kim, Hyo Joong;Lim, Young Jin;Murali, G.;Kim, Min Su;Kim, Gi Heon;Kim, Yong Hae;Lee, Gi-Dong;Lee, Seung Hee
    • Current Optics and Photonics
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    • 제1권2호
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    • pp.157-162
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    • 2017
  • In large liquid crystal displays, the image quality in an oblique viewing direction is a crucial issue. From this perspective, 8-domain polymer-stabilized vertical alignment (PS-VA) mode has been developed to suppress the color shift in oblique viewing directions, compared to that in 4-domain PS-VA mode. To realize the 8-domain PS-VA, the four domains in a pixel are each divided into two regions, such that applying different electric potentials result in different tilt angles in these two regions, while keeping four azimuthal directions in each domain. However, applying different voltages in a pixel causes drawbacks, such as requiring additional processes to construct a capacitor and a transistor, which will further reduce the aperture ratio. Here we propose a different approach to form the 8-domain, by controlling surface polar anchoring energy and the width of patterned electrodes in two regions of a pixel. As a result, the gamma-distortion index (GDI), measured at an azimuthal angle of $0^{\circ}$, is reduced by about 23% and 8%, compared to that of a conventional 4-domain at polar angles of $30^{\circ}$ and $60^{\circ}$ respectively.

EO Characteristics of the ion Beam Aligned TN-LCD on the NDLC Thin Film Surface (NDLC 박막 위에 Ion Beam 배향한 TN-LCD의 전기광학특성)

  • Park, Chang-Joon;Hwang, Jeoung-Yeon;Kang, Hyung-Ku;Ahn, Han-Jin;Kim, Kyung-Chan;Kim, Jong-Bok;Baik, Hong-Koo;Seo, Dae-Shik
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.2
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    • pp.1054-1057
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    • 2004
  • The nitrogenated diamond-like carbon (NDLC) exhibits high electrical resistivity and thermal conductivity that are similar to the properties shown by diamond-like carbon (DLC) films. These diamond-like transparent properties in NDLC come in a material consisting of $sp^2$-bonded carbon versus the $sp^3$-carbon of DLC. The diamond-like properties and nondiamond-like bonding make NDLC an attractive candidate for applications. Liquid crystal (LC) alignment capabilities with ion beam exposure on NDLC thin films and electro-optical (EO) performances of the ion-beam-aligned twisted nematic liquid crystal display (TN-LCD) with oblique ion beam exposure on the NDLC thin film surface were studied. An excellent uniform alignment of the nematic liquid crystal (NLC) alignment with the ion beam exposure on the NDLC thin films was observed. In addition, it can be achieved that the good EO properties of the ion-beam-aligned TN-LCD. Finally, we will present the residual DC property of the ion-beam-aligned TN-LCD on the NDLC thin film surface.

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High-Performance Single-Crystal Organic Nanowire Field-Effect Transistors of Indolocarbazole Derivatives

  • Park, Gyeong-Seon;Jeong, Jin-Won;Seong, Myeong-Mo
    • Proceedings of the Korean Vacuum Society Conference
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    • 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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    • pp.368-368
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    • 2012
  • We report solution-processed, high-performance single-crystal organic nanowire transistors fabricated from a novel indolocarbazole (IC) derivative. The direct printing process was utilized to generate single-crystal organic nanowire arrays enabling the simultaneous synthesis, alignment and patterning of nanowires using molecular ink solutions. Using this method, single-crystal organic nanowires can easily be synthesized by self-assembly and crystallization of organic molecules within the nanoscale channels of molds, and these nanowires can then be directly transferred to specific positions on substrates to generate nanowire arrays by a direct printing process. These new molecules are particularly suitable for p-channel organic field-effect transistors (OFETs) because of the high level of crystallinity usually found in IC derivatives. Selected area diffraction (SAED) and X-ray diffraction (XRD) experiments on these solution-processed nanowires showed high crystallinity. Transistors fabricated with these nanowires gave a hole mobility as high as 1.0 cm2V-1s-1 with nanowire arrays with the direct printing process.

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The Structural Effects on The Pretilt Angle of Alignment Materials with Alkylcyclohexylbenzene as a Side Chain in Polyimides

  • Lee, Jong-Beom;Lee, Hyun-Kyung;Park, Jae-Chul;Kim, Yong-Bae
    • 한국정보디스플레이학회:학술대회논문집
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    • 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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    • pp.1188-1192
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    • 2004
  • Polyamic acid precursors were prepared by mixing various main chain dianhydrides, main chain diamines and side chain diamines. Copolyimide films with alkylcyclohexylbenzene as a side chain were prepared by thermal imidization of polyamic acid precursors. Pretilt angles on rubbed polyimides changed according to the side chain and main chain structures of the polyimide. Consequently, we found that LC pretilt angles of polyimide films with a liquid crystal structure as a side chain showed to be approximately 90$^{\circ}$ when a linear and rigid polyimide main chain and a side chain of suitable length were employed.

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PDMS-based pixel-wall bonding technique for a flexible liquid crystal display (플렉서블 액정 디스플레이를 위한 PDMS 기반 pixel-wall bonding 기술)

  • Kim, Young-Hwan;Park, Hong-Gyu;Oh, Byeong-Yun;Kim, Byoung-Yong;Paek, Kyeong-Kap;Seo, Dae-Shik
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 한국전기전자재료학회 2008년도 춘계학술대회 및 기술 세미나 논문집 디스플레이 광소자
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    • pp.42-42
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    • 2008
  • Considerable attention has been focused on the applications of flexible liquid crystal (LC)-based displays because of their many potential advantages, such as portability, durability, light weight, thin packaging, flexibility, and low power consumption. To develop flexible LCDs that are capable of delivering high-quality moving images, like conventional glass-substrate LCDs, the LC device structure must have a stable alignment layer of LC molecules, concurrently support uniform cell gaps, and tightly bind two flexible substrates under external tension. However, stable LC molecular alignment has not been achieved because of the layerless LC alignment, and consequently high-quality images cannot be guaranteed. To solve these critical problems, we have proposed a PDMS pixel-wall based bonding method via the IB irradiation was developed for fasten the two substrates together strongly and maintain uniform cell gaps. The effect of the IB irradiation on PDMS with PI surface was also evaluated by side structure configuration and a result of x-ray photoelectron spectroscopic analysis of PDMS interlayer as a function of binder with substrates. large number of PDMS pixel-walls are tightly fastened to the surface of each flexible substrate and could maintain a constant cell gap between the LC molecules without using any other epoxy or polymer. To enhance the electro-optical performance of the LC device, we applied an alignment method that creates pretilt angle on the PI surface via ion beam irradiation. Using this approach, our flexible LCDs have a contrast ratio of 132:1 and a response time of about 15 ms, resulting in highly reliable electro-optical performance in the bent state, comparable to that of glass-substrate LCDs.

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Study on Electro-Optical Specific of Polyimide and Organic Overcoat (PI와 유기 절연막 과의 전기광학 특성 비교에 관한 연구)

  • Kim, Byoung-Yong;Kim, Jong-Hwan;Han, Jeong-Min;Kim, Young-Hwan;Kang, Dong-Hoon;Kim, Jong-Yeon;Ok, Chul-Ho;Seo, Dae-Shik
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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    • pp.376-376
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    • 2007
  • In Liquid Crystal Display (LCD) manufacturing, the organic over coat materials over coat materials for insulation layer of color filter with acryl ate was widely used. Therefore, we approach that the organic overcoat material can use to insulation layer for color filter and liquid crystal (LC) alignment layer in this research. The LC aligning capabilities was successful stuided for the first time. The organic overcoat layer and polymer layer was coated by spin-coating. In order to characterize the LC alignment, electric optic and residual DC and atomic force microscopy (AFM) image was used. The good LCD aligning capabilities treated on the organic overcoat thin film surfaces with ion beam exposure of $45^{\circ}$ above ion beam energy density of 1200 eV can be achieved. Also the good LCD alignment capabilities treated polymer on surfaces with ion beam exposure of $45^{\circ}$ above ion beam energy density of 1800 eV can be achieved. Comparing electro-optical characteristics between the Polyimide (PI) and the overcoat, the resultant transmittance of the overcoat considerably matched that of the PI and the residual DC also exhibited similar features with the PI.

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Liquid crystal aligning capabilities for vertical aligned NLC on the $CeO_x$ thin film layer with thermal evaporation

  • Han, Jin-Woo;Kim, Mi-Jung;Kim, Jong-Yeon;Han, Jeong-Min;Kim, Young-Hwan;Kim, Jong-Hwan;Kim, Byoung-Yong;Seo, Dae-Shik
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 한국전기전자재료학회 2007년도 추계학술대회 논문집
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    • pp.371-371
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    • 2007
  • In this study, liquid crystal (LC) aligning capabilities for vertical alignment on the $CeO_x$ thin film by thermal evaporation method were investigated. Also, the control of pretilt angles and thermal stabilities of the NLC treated on $CeO_x$ thin film were investgated. The uniform LC alignment on the $CeO_x$ thin film surfaces and good thermal stabilities with thermal evaporation can be achieved. It is considerated that the LC alignment on the $CeO_x$ thin film by thermal evaporation is attributed to elastic interaction between LC molecules and micro-grooves at the $CeO_x$ thin film surface created by evaporation. In addition, it can be achieved the good electro-optical (EO) properties of the VA-LCD on $CeO_x$ thin film layer with oblique thermal evaporation.

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Design of Alignment Mark Stamper Module for LED Post-Processing

  • Hwang, Donghyun;Sohn, Young W.;Seol, Tae-ho;Jeon, YongHo;Lee, Moon G.
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • 제24권2호
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    • pp.155-159
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    • 2015
  • Light emitting devices (LEDs) are widely used in the liquid crystal display (LCD) industry, especially for LCD back light units. Therefore, much research has been performed to minimize manufacturing costs. However, the current process does not process LED chips from broken substrates even though the substrate is expensive sapphire wafer. This is because the broken substrates lose their alignment marks. After pre-processing, LED dies are glued onto blue tape to continue post-processing. If auxiliary alignment marks are stamped on the blue tape, post-processing can be performed using some of the LED dies from broken substrates. In this paper, a novel stamper module that can stamp the alignment mark on the blue tape is proposed, designed, and fabricated. In testing, the stamper was reliable even after a few hundred stamps. The module can position the stamp and apply the pattern effectively. By using this module, the LED industry can reduce manufacturing costs.

Electro-Optical Performances of In plane Switching(IPS) Cell on the Inorganic Thin Film by Ion Beam(IB) Method (NDLC박막에 이온빔배향법을 사용한 In Plane Switching(IPS) cell의 전기광학특성)

  • Kim, Sang-Hoon;Kim, Jong-Hwan;Kang, Dong-Hoon;Kim, Young-Hwan;Hwang, Jeoung-Yeon;Seo, Dae-Shik
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 한국전기전자재료학회 2006년도 학술대회 및 기술세미나 논문집 디스플레이 광소자
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    • pp.64-65
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    • 2006
  • We studied the nematic liquid crystal (NLC) alignment capability by the IB(on bean) alignment method on a NDLC(Nitrogen Diamond Like Carbon) as a-C:H thin film, and investigated electro-optical performances of the IB aligned IPS(In plane switching}cell with NDLC surface. A good LC alignment by IB exposure on a NDLC surface was achieved. Monodomain alignment of the IB aligned IPS cell can be observed. The goodelectro-optical (EO) characteristics of the IB aligned IPS cell was observed with oblique IB exposure on the NDLC as a-C:H thin film for 1 min.

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