• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.479-482
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• 2004

We report a method for simultaneous measurements of cell gap, twist angle, birefringence dispersion of liquid crystal (LC) material and alignment directions in filled reflective LC cells. The method is based on spectral measurements of the LC cell reflectivity for three orientations ($0^{\circ},45^{\circ},90^{\circ}$) of the exit polarizer and may be applied for LC cells with low and high gaps.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.305-308
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• 2003

We fabricated a flexible ferroelectric liquid crystal (FLC) device containing polymer walls and networks which fix plastic film substrates. The device using 100-${\mu}m$-thick substrates could be bent in a radius of 7mm without disordering the FLC alignment. When sandwiched between polarizers a roll-up display with high-speed grayscale capability for moving-image displays was created.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.299-304
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• 2003

We discuss several key technologies of liquid crystal displays (LCDs) that share common features of all organic displays (AODs). An overview of the morphological effects associated with molecular ordering at interfaces on the Crystallinity and the carrier mobility in organic thin film transistors (OTFTs) is given from the viewpoint of the alignment mechanism for LCDs. Recent progress of improving the carrier mobility in the OTFTs is also reviewed.

• 전자공학회논문지D
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• 제34D권3호
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• pp.114-122
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• 1997

The surface characteristics of polymers for liquid crystal alignment are studied by optical second-harmonic genertion (SHG) tecnique. Using SHG technique, the LC monolayers on rubbed polymer have already been studied. But, in this paper, the SH signals of polymer were observed and the orientational distribution of oriented polymer was studied. Te SHG experiments for side-chain type and main-chain type polymers are carried out as a function of rubbing strength. The orentational distribution of surface molecules of polymers is compared with the LC pretilt angle measured by the crystal rotation method.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2002년도 International Meeting on Information Display
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• pp.452-455
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• 2002

We demonstrate the wide-viewing characteristics of a twisted nematic liquid crystal display (LCD) with self-formed micro-domains through the topographical alignment and fringe field effects of dielectric surface gratings (DSG). The mutual optical compensation between micro-domains within each pixel eliminates the contrast inversion phenomenon of TN mode without complex surface treatments.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.I
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• pp.97-100
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• 2005

The recent Bistable Nematic ($BiNem{(R)}$) LCD technology presents long term bistability, high level passive matrix multiplexing and high optical quality. The BiNem device, based on anchoring breaking, needs specific low anchoring strength materials - alignment layers and liquid crystal mixtures. We present here our approach to develop nematic mixtures with wide enough temperature range and low zenithal anchoring energy.

• 한국방사선학회논문지
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• 제13권6호
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• pp.831-840
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• 2019

액정을 이용하는 X-선 검출기에서 전면광원을 적용하는 액정 X선 검출기를 제안하였고 X선 영상을 찍어 작동을 확인하였다. 제안한 방식은 빛을 이용하므로 트랜지스터를 이용하는 방식에 비해 잡음이 적고 제작 비용을 낮출 수 있다. 액정을 이용하는 검출기는 광도전층을 이용하여 입사 X선을 액정의 분자 배열 변화로 유도하고 액정을 통과하는 빛의 변화량을 읽도록 한다. X선을 조사하고 잰 빛의 투과율과 이것에 대응되는 기준투과율 곡선의 전압으로부터 X선 조사량을 교정(Calibration)하는 과정을 정립하였다. 비정질 셀레늄을 광도전층으로 적용하였으며 200℃ 이상의 고온 처리가 필요한 배향막 공정 대신 패럴린 배향막을 사용하는 공정을 확립하였다. 제안된 액정 X선 검출기의 경우, 방사선량을 획기적으로 줄일 수 있다는 것을 시뮬레이션으로 보였다. 제안된 방식의 X-선 검출기를 제작하고 액정 바이어스 전압을 조절하며 X-선 라인 영상을 비교하였으며 고정 바이어스에서 시간에 따른 이미지 변화를 관찰하였다. 영상사진으로 10 lines/mm의 선패턴을 구별할 수 있었다. 이러한 실험을 바탕으로 검출 패널의 위상이 3π 정도인 17인치 시제품에 적용하여 저선량 액정 X선 검출기의 상용화를 추진할 예정이다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 춘계학술대회 및 기술 세미나 논문집 디스플레이 광소자
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• pp.41-41
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• 2008

In general, polyimides (PIs) are used in alignment layers in liquid crystal displays (LCDs). The rubbing alignment technique has been widely used to align the LC molecules on the PI layer. Although this method is suitable for mass production of LCDs because of its simple process and high productivity, it has certain limitations. A rubbed PI surface includes debris left by the cloth, and the generation of electrostatic charges during the rubbing induces local defects, streaks, and a grating-like wavy surface due to nonuniform microgrooves that degrade the display resolution of computer displays and digital television. Additional washing and drying to remove the debris, and overwriting for multi-domain formation to improve the electro-optical characteristics such as the wide viewing angle, reduce the cost-effectiveness of the process. Therefore, an alternative to non-rubbing techniques without changing the LC alignment layer (i.e, PI) is proposed. The surface of LC alignment layers as a function of the ion beam (IE) energy was modified. Various pretilt angles were created on the IB-irradiated PI surfaces. After IB irradiation, the Ar ions did not change the morphology of the PI surface, indicating that the pretilt angle was not due to microgrooves. To verify the compositional behavior for the LC alignment, the chemical bonding states of the ill-irradiated PI surfaces were analyzed in detail by XPS. The chemical structure analysis showed that ability of LCs to align was due to the preferential orientation of the carbon network, which was caused by the breaking of C=O double bonds in the imide ring, parallel to the incident 18 direction. The potential of non-rubbing technology for fabricating display devices was further conformed by achieving the superior electro-optical characteristics, compared to rubbed PI.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 춘계학술대회 논문집
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• pp.120-122
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• 1997

In this paper, the viewing angle characteristics of amorphous (a) - twisted nematic (TN) - liquid crystal display (LCD) on poly(viny)cirmamate (PVC) alignment surfaces were investigated. It was found that the threshold voltage is increased with increasing the polymerization on PVC surfaces. We suggest that the threshold voltage is affected to the surface anchoring strength with increasing the polymerization of the alignment film. Also, we obtained that the viewing angle of a-TN-LCD is increased with increasing the polymerization on PVC surfaces. Finally, we considered that the viewing angle of a-TN-LCD on PVC surfaces is large compared to TN-LCD on rubbed polyimide (Pl) surface.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.369-372
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• 2001

We studied the electro-optical (EO) performance in the vertical-alignment (VA) - l/4$\pi$ cell photoaligned with polarized UV exposure on a homeotropic photopolymer surfaces. Excellent voltage-transmittance curve in the VA - l/4$\pi$ cell photoaligned with polarized UV exposure for 3 min on the photopolymer containing cholesterol group of 8% can be achieved. The V-T characteristics in the VA-l/4$\pi$ cell photoaligned on the photopolymer surface can be improved by increasing cholesteryl group. For response time measurement, the transmittance characteristics of the VA-l/4$\pi$ cell photoaligned on the photopolymer surface was better than that of the VA-l/4$\pi$ cell rubbingaligned on a polyimide(Pl) surface.