• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.400-400
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• 2007

In this study, we investigated liquid crystal (LC) alignment with ion beam (IB) that non contact alignment technique on polyimide and electro-optical characteristics of twisted nematic (TN)-liquid crystal display (LCD) on the polyimide under various ion beam angles. In this experiment, polyimide layer was coated on glass by spin-coating and Voltage-transmittance(VT) and response time characteristics of the TN cell were measured by a LCD evaluation system. The good characteristics of the nematic liquid crystal (NLC) alignment with the ion beam exposured polyimide surface was observed. In addition, it can be achieved the good EO properties, and residual DC property of the ion beam aligned TN cell on polyimide surface.

• 한국위성정보통신학회논문지
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• 제10권3호
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• pp.89-93
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• 2015

본 연구에서는 이온빔 처리된 $HfO_2$ 박막을 이용한 액정디스플레이의 프리틸트각을 제어함으로써, 작은 구동전압에서도 안정적으로 구동할 수 있는 디스플레이 소자에 응용할 수 있는 특성을 연구하였다. $HfO_2$ 박막의 원자 수준의 증착을 통해서 높은 유전율의 박막을 제조할 수 있었으며, 이는 저전력 구동을 위해서 필수적인 요소라고 생각한다. 또한 이러한 $HfO_2$ 박막의 액정배향성을 확인하여 균일한 액정배향을 통해서 디스플레이 소자로의 응용가능성을 확인하였다. 특히 $HfO_2$ 박막에서의 액정배향성에 대해서 액정배향의 대표적인 특성인 프리틸트각의 제어를 실험을 통해서 확인하였다. 실험결과 이온빔처리를 한 $HfO_2$ 박막에서의 액정배향의 특성을 접촉각특성을 대표화하여 정량화 할 수 있었다. 본 연구의 결과 액정의 배향성 확보 및 프리틸트각을 제어할 수 있는 고유전율 $HfO_2$ 박막의 제조가 가능한 것을 확인할 수 있었으며, 고유전율 특성에서 기인하는 저전력 구동의 가능성을 확인할 수 있었다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.I
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• pp.768-773
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• 2005

We present an overview of our new method of liquid crystal (LC) alignment based on the anisotropic etching of the alignment layers with a directed plasma flux. The method is realized by the use of anode layer source of "race track" geometry generating two "sheets" of accelerated plasma. These sheets are directed obliquely to the treated substrates. The static and dynamic irradiation regimes have been explored. The optimized processing conditions and materials are discussed. The technique yields an excellent uniformity of liquid crystal alignment of planar, tilted and vertical types. It is shown that the new method can be easily adapted for the alignment treatment of large area substrates used in the modern LCD manufacturing process.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.91-94
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• 2009

We propose advanced liquid crystal display (LCD) modes through surface modification using UV curable reactive mesogen (RM) mixed with alignment layers. The LC directors on the modified alignment layer are controlled and memorized by the polymerized RMs under an applied voltage. Using the method proposed here, we can improve the response time and viewing angle characteristics through surface controlled patterned vertical alignment (SC-PVA) mode and 8-domains PVA mode, respectively. Also, we found that the method can be applicable to fabricate multi-domain structures using multiple UV exposure as same as conventional UV alignment method.

• Journal of Information Display
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• 제6권1호
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• pp.1-7
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• 2005

We propose new fabrication methods of a pixel-isolated liquid crystal (LC) structure for flexible display applications. In the LC structure fabricated through the proposed method, the patterned interpixel walls for sustaining the cell thickness are supported by the solidified polymer layer through anisotropic phase separation of LC/polymer composite, causing the alignment of the LC molecules to have very good mechanical stability against external pressure. In addition, we show that such pixel-isolating walls can be made by the stamping method which can be applied to fabricate large size plastic LCDs by roll-to-roll processing.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.615-620
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• 2006

We demonstrate novel soft-lithographic techniques for preparing patterned liquid crystal (LC) orientations at an alignment layer. By controlling patterning conditions such as wetting property and operating temperature depending on polymeric materials, multi-directional or modified LC alignment conditions can be simply achieved.

• 한국전기전자재료학회논문지
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• 제11권4호
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• pp.306-313
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• 1998

To elucidate the liquid crystal(LC) molecules alignment mechanism, it is important to determine the molecular orientation of the rubbed polymer surface molecules that directly contact with LC molecules. In this work, the molecular orientation on a rubbed surface of polyimide (SE-3310, Nissan) film has been studied by polarized FTIR absorption spectroscopy. It has been found that molecular chain on the rubbed surface of polymide film are oriented along the rubbing direction and are tilted up on an average by 5.0$^{\circ}$. In the SHG(Second Harmonic Generation) measurement, the pretilt angle of molecular chain on the poylmide fim was 4.6$^{\circ}$ fro, the surface plane. And the pedit angle of liquid crystal (ZLI-2293, Merck) molecules measured by crystal rotation method was 5.4$^{\circ}$in the same rubbing condition.

• Transactions on Electrical and Electronic Materials
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• 제10권4호
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• pp.140-142
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• 2009

We have investigated the continuous pretilt angle generation for liquid crystals using a rubbing treated mixture layer consisting of homogeneous and homeotropic polyimides. Various pretilt angles in the range from $0^{\circ}$ to $60^{\circ}$ were achieved as a function of the concentration of homeotropic PI. The transmittance characteristics used to measure the pretilt angle showed that the pretilt angles were measured with a high reliability. We observed uniform liquid crystal alignment on the rubbing treated mixture layer.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.429-429
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• 2007

For various applications of liquid crystal displays (LCDs), the uniform alignment of liquid crystal (LC) molecules on treated surfaces is significantly important. Generally, a rubbing method has been widely used to align the LC molecules on polyimide (PI) surfaces. Rubbed PI surfaces have suitable characteristics, such as uniform alignment. However, the rubbing method has some drawbacks, such as the generation of electrostatic charges and the creation of contaminating particles. Thus, we strongly recommend a non contact alignment technique for future generations of large high-resolution LCDs. Most recently, the LC aligning capabilities achieved by ultraviolet and ion-beam exposures which are non contact methods, on diamond-like carbon (DLC) inorganic thin film layers have been successfully studied because DLC thin films have a high mechanical hardness, a high electrical resistivity, optical transparency, and chemical inertness. In addition, nitrogen-doped DLC (NDLC) thin films exhibit properties similar to those of the DLC thin films and a higher thermal stability than the DLC thin films because C:N bonding in the NDLC thin filmsis stronger against thermal stress than C:H bonding in the DLC thin films. Our research group has already studied the NDLC thin films by an ion-beam alignment method. The $SiN_x$ thin films deposited by plasma-enhanced chemical vapor deposition are widely used as an insulation layer for a thin film transistor, which has characteristics similar to those of DLC inorganic thin films. Therefore, in this paper, we report on LC alignment effects and pretilt angle generation on a $SiN_x$, thin film treated by ion-beam irradiation for various N ratios

• Macromolecular Research
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• 제14권1호
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• pp.1-33
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• 2006

Polyimides (PIs) exhibit excellent thermal stability, mechanical, dielectric, and chemical resistance properties due to their heterocyclic imide rings and aromatic rings on the backbone. Due to these advantageous properties, PIs have found diverse applications in industry. Most PIs are insoluble because of the nature of the high chemical resistance. Thus, they are generally used as a soluble precursor polymer, which forms complexes with solvent molecules, and then finally converts to the corresponding polyimides via imidization reaction. This complexation with solvent has caused severe difficulty in the characterization of the precursor polymers. However, significant progress has recently been made on the detailed characterization of PI precursors and their imidization reaction. On the other hand, much research effort has been exerted to reduce the dielectric constant of PIs, as demanded in the microelectronics industry, through chemical modifications, as well as to develop high performance, light-emitting PIs and liquid crystal (LC) alignment layer PIs with both rubbing and rubbing-free processibility, which are desired in the flat-panel display industry. This article reviews this recent research progresses in characterizing PIs and their precursors and in developing low dielectric constant, light-emitting, and LC alignment layer PIs.