• Proceedings of the Optical Society of Korea Conference
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• 2004.02a
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• pp.138-139
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• 2004

In this paper, we propose a reflective In-Plane Switching twisted nematic mode with negative liquid crystal and weak surface anchoring energy (10$^{-6}$ J/m) in order to enhance reflectance and cellgap margin.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.290-292
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• 2007

A twisted nematic type liquid crystal electro-optic modulator (TN-LC modulator) was developed. The modulator used single polarizer and the reflection on-off ratio was maximized by optimization of twist angle and retardation of liquid crystal cell. The TNLC modulator shows better sensitivity and response time than conventional liquid crystal modulator.

• Korean Journal of Optics and Photonics
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• v.21 no.2
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• pp.69-73
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• 2010

We propose a method to enhance the response time of a twisted nematic liquid crystal (TN-LC) cell using an anisotropic polymer. Polymer networks are formed by the phase separation between a LC and a UV-curable polymer. A TN-LC cell is exposed to UV light after the mixture of LC and anisotropic polymer is injected into the TN-LC cell. As a result, turn-off time of a TN-LC cell can be decreased remarkably without any loss of the transmittance. The turn-off time of a TN-LC cell with pure LC was 16 ms, but those of polymer networked TN-LC cells were 12, 11, and 9 ms when the concentration of the polymer was 3, 5, and 10 wt%, respectively. Moreover, by virtue of the polymer network, the backflow effect and the delay time generated during the turn-off process disappeared.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.271-272
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• 2009

We fabricated a hybrid aligned film using reactive rod-like mesogen to reduce light leakage of twisted nematic(TN) cell in off-axis of the dark state. We proved that the fabricated compensation film has hybrid alignment by changing phase retardation according to polar angle. In this paper, we confirmed characteristics of compensation film through simulation results and found the matching factor of simulation results and experimental result. In result, the maximum pretilt angle of hybrid compensated film is $19^{\circ}$ which has phase retardation 0.1445.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.1054-1057
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• 2003

We have studied $90^{\circ}$ twisted nematic (TN) mode driven by fringe electric field, where two polarizers are parallel each other such that the cell shows a black state before a voltage is applied. According to the studies by computer simulation for a LC with negative dielectric anisotropy, the LC twists perpendicular to the horizontal field direction of fringe electric field and the degree of tilt angle is very low, when a voltage is applied. Therefore, the new device exhibits wide viewing angle characteristic due to in-plane switching and high transmittance since the LC director aligns parallel to the polarizer axis.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.297-298
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• 2005

We have fabricated twisted nematic (TN) liquid crystal cells doped by carbon nanotubes (CNTs) with different CNT wt. %. With a minute amount doping, multi-walled CNTs did not perturb the liquid crystal orientations at the off- and on-state. The hysteresis studies of voltage-dependent capacitance (V-C) under the influence of electric field generated by ac and dc voltage show that the residual do, which is tightly related to image sticking problem in liquid crystal displays, is greatly reduced due to ion trapping by CNTs. Also, the V-C hysteresis shows dependency of capacitance on concentration of multi-walled CNTs.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.289-290
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• 2005

We have investigated the electro-optical (EO) performances of the flexible liquid crystal display (LCD) on twisted nematic (TN) mode according to variation of cell gap in comparison with glass LCD. There were four kinds of cells which were having cell gaps of 3$\mu$m, 4$\mu$m and 5$\mu$m, especially the lowest 2$\mu$m on flexible and glass substrates separately. The EO performances of the flexible cells on the rubbed potyimide (PI) were almost the same those of glass cells. The response time of flexible cells was shorter than that of glass cells but the alignment of liquid crystal (LC) of flexible cells was weaker than that of glass cells. The residual DC of flexible cells was on the increase like that of glass cells in compliance with lowering cell gap.

• Korean Journal of Optics and Photonics
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• v.19 no.1
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• pp.48-53
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• 2008

We propose an optical configuration to compensate dispersion characteristics in the dark state of normally black twisted nematic (NB-TN) liquid crystal display (LCD). We employed a half-wave plate (HWP) and a +A plate to achieve the superior dark state. By using the parameter space diagram (PSD) method, we could obtain the optimum values of parameters and the high contrast-ratio over 500 : 1 could be obtained. Furthermore, excellent dispersion characteristics were also obtained in the bright state. We could confirm the performance of the proposed structure using both the numerical calculations and the experiments.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.10
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• pp.1095-1099
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• 2004

We investigated the electro-optica](EO) performances of the super twisted nematic liquid crystal display(STN-LCD) on the polyimide(PI) surface using polymer film. The NLC(Nematic Liquid Crystal) pretilt angles generated are about 18$^{\circ}$by the rubbing alignment method on thin plastic substrates. However, the pretilt angle are at about 13$^{\circ}$ lower on the glass substrate than on thin plastic substrate. Monodomain alignment of the plastic STN-LCD can be observed. A stable voltage-transmittance(V-T) curve of the plastic STN-LCD was observed on the polyimide(PI) surfaces using polymer film. Also, a faster response time for the plastic STN-LCD on the polyimide(PI) surfaces using polymer film can be achieved.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.514-517
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• 2002

We investigated response characteristics of twisted nematic (TN) cell with different nematic liquid crystals (NLCs) and cell gap d on a rubbed polyimide (PI) surface. High transmittance and fast response time of the TN cell on the rubbed PI surface were achieved by using high birefringence (${\Delta}n$) and low cell gap d. The response time of TN cell on the rubbed PI surface was measured 5.1 ms. The transmittance and response time of the TN cell on the rubbed PI surface decreased with decreasing ${\Delta}nd$.