• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.453-456
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• 2005

Color characteristics of a dark state in the IPS-mode depending on viewing direction have been studied. IPS-mode is having a little variation of $d{\Delta}n$ with viewing angle since the LC rotates in plane. However, this mode shows asymmetric light leakage and color characteristics with viewing angle in a dark state. This drawback can be overcome by optimized retardation value of TAC film, pre-tilt angle & $d{\Delta}n$ of LC.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.895-898
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• 2004

We propose configurations for a transflective in-plane switching (IPS) cell using muti-domain structures. Usually, the cell configurations for a transflective liquid crystal(LC) cell have a complicated structure, because retardation change of transmissive part and reflective part are not same. The transflective LC cell should have two configurations for each part, such as a multi-cell gap structure. With the ion-beam alignment and the horizontal switching LC cell, a simple structure for a transflective LC cell is proposed. The configuration only adopts one cell gap structure, which may help the enhancement of a yield. Their original optical properties in conventional transmissive and reflective type IPS liquid crystal dispaly(LCD) are kept, it shows the wide-viewing angle and the good wavelength dispersion characteristics.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.527-530
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• 2007

Film compensation to suppress a light leakage in the dark state of fringe-field switching (FFS) at off normal direction was performed by optimizing retardation value of discotic (negative A) and TAC films including in-plane switching (IPS). The normal FFS mode shows wide viewing angle characteristics that region of CR 10:1 is over $70^{\circ}$ of polar angle in all directions. The optimized FFS cell exhibits much better performances than other methods do in terms of CR and color uniformity.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05a
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• pp.153-156
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• 2004

We have studied electro-optic characteristics of transflective liquid crystal display (LCD) using in-plane switching mode. Unlike previous transflective LCD using a dual gap structure and multi driving circuit, this transflective LCD has a single gap structure and a single driving circuit. In the voltage on state, the electric field is applied horizontally to the LC directors, and then homogeneously aligned LC directors at initial state is rotated to with the electric field. But the twist angle of the LC directors in reflective area is lower than transmissive area. As a result, it is possible to design the transflective LCD with a single gap and a single driving circuit. The transflective display associated with this LC cell exhibits a wide viewing angle in both reflective and transmissive areas.

• Proceedings of the Optical Society of Korea Conference
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• 2005.02a
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• pp.326-327
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• 2005

• Journal of Information Display
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• v.10 no.4
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• pp.175-179
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• 2009

As the physical properties of nematic liquid crystals vary with respect to temperature, the performances of liquid crystal displays (LCDs) are highly dependent on temperature. Additionally, it is well known that the electro-optic characteristics of LCDs, such as transmittance and threshold voltage, also rely on the LCD switching modes. The temperature dependence of the electro-optic characteristics of the wide-viewing-angle LCD modes, such as in-plane switching (IPS), multidomain vertical alignment by patterned electrode (PVA), and fringe-field switching (FFS), have been studied, and the results showed that the FFS mode has lower temperature dependence compared to the IPS and PVA modes. Since the liquid crystal (LC) reorients in different ways in each mode, this result is associated with the temperature dependence of LC's bend and twist elastic constants, and also with the position of the main reorientation, either in the middle or on the surface of the LC layer.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.05a
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• pp.100-103
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• 2005

Homogeneously aligned nematic liquid crystal modes are representatively the -FFS (fringe-field switching) mode using liquid crystal (-LC) with negative dielectric anisotropy, the +FFS mode and the IPS (in-plane switching) mode using +LC with positive dielectric anisotropy. In view of image quality evaluation standard of LCD, we compared characteristics of the brightness, the contrast ratio (CR) and color shift when the modes have respectively optimized phase retardation values $(d{\Delta}n)$. Consequently, in the most sensitively viewing angle of a man's physical vision, both FFS modes have advantage over the IPS mode from the brightness & the CR point of view. We are also confirmed that the +FFS mode out of them shows the smallest color shift according to all viewing directions in grey levels.

• Information Display
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• v.14 no.1
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• pp.30-37
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• 2013

지난 20년 동안 TFT-LCD의 화질은 급격하게 발전해 왔다. 특히 IPS와 VA의 기술경쟁을 통해 서로의 단점을 극복하려는 많은 연구가 수행돼왔다. 하지만 이제는 발광디스플레이의 출현으로 이제는 액정기술 간의 경쟁은 의미 없고 TFT-LCD의 화질/기능/비용면에서 발광디스플레이보다 우수해야 하는 당면 과제를 안고 있다. 현재 IPS기술은 FFS기술을 통해 한층 더 발전하였고 이제는 고화질 제품엔 FFS 채용이 기본화되고 있다. FFS 기술개발에 초기부터 참여하고 지금까지 FFS기술을 연구하고 있는 필자의 관점에서 보면 FFS는 1998년 발표이후 매 6년 마다 중대한 변화가 있었고 그 예가 2004년 히타치사 TV패널에 FFS기술 적용, 2010년 애플사 아이패드에 FFS 기술 채용이다. 현재 기술 흐름으로 볼 때 2016년 정도엔 FFS기술 + 산화물 반도체 + 광배향 기술을 적용한 FFS TV가 시장의 한 축이 되길 필자는 기대해본다. 마지막으로 필자의 경험을 바탕으로 평가한 각 기술들에 대해 다른 전문가들과 이견이 있을 수 있음을 인정하니 많은 양해 부탁드립니다.

• 한국정보디스플레이학회:학술대회논문집
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• 2000.01a
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• pp.11-12
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• 2000

An 18.1" Thin Film Transistor Liquid Crystal Display (TFT LCD) monitor adopting high brightness In Plane Switching (IPS) technology was realized. While conventional IPS structure used a Chromium (Cr) and Molybdenum (Mo) for a drain electrode, Indium Tin Oxide (ITO) was proposed and verified in this paper. Black sticky micropeal spacers were introduced for the reduction of light scattering phenomena, which was observed at dark room with the conventional micropeal spacers. With the proposed method, more than 10 % aperture ratio was increased and the excellent image quality was obtained.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.05a
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• pp.104-108
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• 2005

We have studied electrode-optic characteristics of IPS (in-plane switching) mode with electrode on top substrate. Because the IPS mode does not have electrode on top substrate. it shows not only slow response time due to weak electric field but also slow discharging problem when electrostatic field is generated after fabricating the cell. To solve these problems. we have formed additional electrode including dielectric layer in the inner part of the cell and studied electrode-optic characteristics of new IPS cell by changing thickness of dielectric layer.