• Journal of Satellite, Information and Communications
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• v.10 no.1
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• pp.67-70
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• 2015

We studied the state of the dual liquid crystal (LC) alignment which displays both homeotropic and homogeneous alignment on blended polyimide (PI) layer. The research was conducted using rubbing method at different imidizing temperatures and the blended PI was made using homeotropic PI having an alkyl side chain and homogeneous PI without the side chain. The uniform LC alignments were achieved, and have thermal stability. The results of contact angles were similar to that of pretilt angles.

• Korean Journal of Optics and Photonics
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• v.14 no.5
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• pp.498-503
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• 2003

We analyze the electro-optic polarization transmission characteristics of liquid crystal cells in the Poincare sphere representation. We determine fundamental conditions on maximizing of brightness and contrast ratio of liquid crystal display devices for polychromatic light by use of retardation films. For optimizing two colors, at least two properly designed retardation films are needed, and for three wavelengths, either it can be approximated to the two-color case or three retardation films are needed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.11a
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• pp.180-182
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• 1996

In this study, we have investigated the characteristics of the response time and the viewing angle on twisted nematic (TN)-liquid crystal display (LCD) and amorphous (a) TN-LCD without rubbing. To measure the transmission-voltage, response time, and viewing angle characteristics, we prepared three kinds of LC cells and then studied the surface liquid crystal alignment effect. We studied that the response time on a-TN-LCD is fast compared to the TN-LCD. We suggest that the weak anchoring strength is attributed to the fast response time on a-TN-LCD. Also, we obtained the uniform viewing angle characteristics on a-TN-LCD. From these results, we consider that the liquid crystal alignment on LCD device are very important factor for electro-optical characteristics.

• 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.

• Journal of Information Display
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• v.12 no.2
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• pp.97-99
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• 2011

We report flexible, bistable cholesteric displays utilizing polyester (PET) substrates with printed internal black electrodes. The black electrodes consist of carbon ink dispersed in butyl carbitol using a patented roll-to-roll gravure-offset printing. A transparent conducting polymer printed on PET serves as the counter electrode. The electro-optic material is a chiral nematic mixture dispersed in a low-concentration polymer binder. The device can be switched between scattering (black) and reflective (vibrant green) states upon application of an electric pulse. The internal black electrode enhances the contrast of the display and simplifies the roll-to-roll manufacture of flexible displays.

• Journal of Sensor Science and Technology
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• v.7 no.6
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• pp.432-436
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• 1998

Recently, the PDLC(Polymer Dispersed Liquid Crystal) is being developed lively to make a large display device using a liquid crystal. Because of low light loss, high brightness, and simple fabrication process, it is made easily to large display device, In this study, the response time and light transmittance by the applied voltage is measured to analyze the electro-optical characteristics of PDLC. The He-Ne laser is applied to the PDLC cell, the light transmittance is measured using the photodiode and the result is analyzed and displayed graphically by the digital oscilloscope. The result of comparison between the PDLC and the present LCD is used to study the potential as a display device.

• Journal of Information Display
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• v.10 no.4
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• pp.184-187
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• 2009

A liquid crystal device with switchable dynamic and memory modes was investigated and developed. The proposed device reveals the splay, $\pi$-twist, and bend states via selective switching among them. In the dynamic mode, the device is operated in the bend state, which exhibits a wide viewing-angle and a fast-response-time due to its self-compensated bend structure and flow-accelerated fast response time, respectively. In the memory mode, the permanent memory characteristics in the splay and $\pi$-twist sates are obtained, respectively. The switching mechanisms of the tristate device are also proposed.

• 정보저장시스템학회:학술대회논문집
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• 2005.10a
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• pp.151-152
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• 2005

Blu-ray 디스크에서는 NA=0.85 의 높은 개구수를 채용함으로써 디스크 보호층의 두께 변동에 따른 구면수차 발생량이 매우 커지는 문제가 발생하게 된다. 따라서 디스크 두께 공차 $3{\mu}m$에서 Blu-ray 시스템의 수차 발생 허용수준을 초과한다. 그리고 Multi-layer 디스크의 경우 각 층의 간격이 $25{\mu}m$ 정도의 간격을 두고 배치되어 있어 기록층 사이에서 발생하는 구면수차의 보정이 필요하며, 종래의 기술은 보상범위가 $3{\mu}m$로 한정되어 사용이 불가능하며 또한 대물렌즈 조립공차가 엄격히 관리되어야 하는 문제점을 안고 있었다. 본 연구에서는 액정렌즈에 의한 구면수차 보정으로 이러한 문제점들을 해결하고자 하였다. 액정렌즈는 오목렌즈 액정소자와 볼록렌즈 액정소자로 구성되며 픽업 광학계 내에 조합하여 설계함으로써 Multi-layer 디스크의 두께 변동에 따라 발생하는 구면수차를 보정하고 대물렌즈 조립공차 문제를 해결할 수 있다.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.600-603
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• 2009

The liquid crystal device with switchable dynamic mode and memory mode has been investigated and developed. The proposed device reveals splay, ${\pi}$ twist and bend states by selective switching among them. In the dynamic mode, this device is operated in the bend state which exhibits the wide view angle and fast response time properties due to the self-compensated bend structure and flow accelerated fast response time. In the memory mode, the permanent memory characteristics in the splay and ${\pi}$ twist sates are obtained, respectively. The switching mechanisms of the tristate device are also proposed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.312-313
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• 2008

A transflective liquid crystal displays associated with fringe field switching (FFS) mode of new concept is proposed. The device utilizes unique characteristic of the FFS mode in which the rotation angle of LC director is strongly dependent on electrode position in on state. We use the liquid crystal with negative dielectric anisotropy. Also we are look for optimized electrode size and the optimization of pixel electrode width and distance between them, the LC director could rotate about $22.5^{\circ}$ and $45^{\circ}$ depending on electrode positions. Consequently, we get high transmittance and high reflection on the optimized electrode condition. Respectively, a high image quality transflective display with single gap and single gamma characteristics realized.