• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.401-402
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• 2008

We proposed a single gap transflective liquid crystal display (LCD) using a vertically aligned (VA) liquid crystal cell and circular polarizer. The conventional VA transflective LCDs have problems that there required several compensation films and voltage-dependent transmittance and reflectance curves do not match each other. To solve these problems, we used circular polarizer and optimized the condition of insulator thickness in the transmissive part and reflective part. Also, we used the patterned vertical alignment (PVA) mode for wide viewing angle in transmissive part. Consequently, this device realized transflective LCD with a single cell gap and single gamma curve.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.04a
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• pp.43-44
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• 2006

We have studied effect of Patterned Vertical Alignment (PVA) mode on electro-optical characteristics and stability of liquid crystal director upon electrode pattering. In the present studies, LC director field and stability of conventional PVA mode electrode patterns were analyzed and new type of electrode patterns were suggested. At last, comparison between this new type of electrode patterns to conventional electrode pattern types were followed.

• Journal of Information Display
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• v.8 no.3
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• pp.17-21
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• 2007

We introduce a new electrode structure for the patterned vertical alignment (PVA) mode, which has a lower color-shift at large viewing angle than the one-domain VA mode. By manipulating the period of electrode structure, we can make more multi-domains and use the existing fabrication processes without having to use additional materials.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.571-573
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• 2007

It is known that the main source of the area image sticking is the ion charge adsorption on the alignment layer. We found out that the adsorption of the ion charge of the liquid crystal in the cell was physisorption, which takes place between all molecules on any surface providing the adsorption force is small.

• Current Optics and Photonics
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• v.1 no.2
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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.

• Journal of Electrical Engineering and Technology
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• v.4 no.4
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• pp.546-551
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• 2009

In this paper, we describe a self-aligned fabrication method for a nano-patterned bottom electrode using flood exposure from the backside. Misalignments between layers could cause the final devices to fail after the fabrication of the nano-scale bottom electrodes. A self-alignment was exploited to embed the bottom electrode inside the glass substrate. Aluminum patterns act as a dry etching mask to fabricate glass trenches as well as a self-aligned photomask during the flood exposure from the backside. The patterned photoresist (PR) has a negative sidewall slope using the flood exposure. The sidewall slopes of the glass trench and the patterned PR were $54.00^{\circ}$ and $63.47^{\circ}$, respectively. The negative sidewall enables an embedment of a gold layer inside $0.7{\mu}m$ wide glass trenches. Gold residues on the trench edges were removed by the additional flood exposure with wet etching. The sidewall slopes of the patterned PR are related to the slopes of the glass trenches. Nano-scale bottom electrodes inside the glass trenches will be used in beam resonators operating at high resonant frequencies.

• Journal of the Optical Society of Korea
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• v.18 no.6
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• pp.783-787
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• 2014

This paper presents an improved vertical alignment nematic liquid crystal mode characterized by the protrusions or slits of the top substrate and additional stripe type common electrodes with polarity switching of the bottom substrate to improve multi-domain vertically aligned (MVA) and patterned vertically aligned (PVA) nematic modes. MVA and PVA modes have disadvantages such as an LC disclination in the vicinity of the middle region of electrodes between the top and bottom protrusions in MVA mode or the top and bottom slits in PVA mode. Therefore, the stripe type common electrode generating a horizontal electric field and the protrusion or slit producing some pretilt of liquid crystals (LCs) were used to improve the LC disclination, which influences the transmittance and response speed. The simulation results showed that the proposed VA mode has higher transmittance than the MVA and PVA modes. As a result, the proposed VA mode can improve the response speed and transmittance remarkably, which makes it useful for upgrading the LCD display quality.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.403-406
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• 2005

We optimized a patterned-vertical-alignment (PVA) transflective liquid-crystal (LC) cell for small pixel application. To achieve the high resolution display performance in the mobile communication equipments such as mobile phones, personal data assistants, and tablet personal computers, we optimized the parameters of liquid crystal and the electrode structure. Both the transmittance and the reflectance are maximized at the same time.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.437-438
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• 2008

The Conventional patterned vertical alignment (PVA) device shows a very high contrast ratio at normal direction and does not require rubbing process. However it has a disclination area in which the liquid crystal can be collision in the boundary domain region. In this paper, we studied PVA(Z-shape) device in which the liquid crystal can be tilted down in multiple directions stably because the surface pretilt angle is controlled by photopolymerization of the UV - curable reactive mesogen (RM) under a proper condition. Consequently, the device shows improved electro optical properties as compared to conventional PVA mode.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.339-340
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• 2008

The Conventional PVA (patterned vertical alignment) mode showed characteristics of 8-domain using T-T type or C-C type. But these methods have disadvantages such as decreasing aspect ratio and transmittance. In order to resolve these problems, in this paper we have studied a new 8-domain method which is partially using the UV curable reactive mesogen (RM) that is a role in surface stabilization. The characteristic of off-axis color shift is decreased because the part of surface stabilized area is compensated to other area in a pixel. Consequently, the device shows improved color shift by 8-domain.