• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.5
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• pp.536-540
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• 2004

A novel nematic liquid crystal (LC) cell with splay structure exhibiting wide viewing angle, fast response time and high transmittance at the same time has been developed. With rubbed homeotropic alignment in parallel directions, the device shows bend alignment in the absence of vertical electric field. However, with applied high voltage in a pulse form, the LC shows a optically compensated splay (OCS) orientation such that the mid-director is parallel to a substrate and at both surfaces the LCs are aligned vertically in parallel direction. In the device, the birefringence of the cell becomes tunable with applying voltage, i.e., the amount of light passed through the cell can be controlled by controlling the orientation of the LC. Since the OCS cell has a self-compensation structure such that the LC has a mirror symmetry along the mid-director, the device shows a wide viewing angle with only a single domain and a fast response time.

• 한국정보디스플레이학회:학술대회논문집
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• 2000.01a
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• pp.9-10
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• 2000

The wide viewing angle and fast response time characteristics of negative dielectric anisotropy nematic liquid crystal (NLC) using a novel vertical-alignment (VA) - 1/4 ${\pi}$ cell mode on a homeotropic alignment layer were investigated. Good voltage-transmittance curves and low driving voltage using the novel VA - 1/4 ${\pi}$ cell mode without a negative compensation film were obtained. The iso-viewing angle characteristics of NLC using the novel VA - 1/4 ${\pi}$ cell mode without a negative compensation film can be achieved. The fast response time of 24.4 ms in NLC was successfully measured. The iso-viewing angle, fast response time, and low driving voltage characteristics using the novel VA - 1/4 ${\pi}$ cell mode can be achieved.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.433-435
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• 2005

We have studied the realigning behavior of liquid crystal molecules in liquid crystalline polymer/liquid crystal(LCP/LC) system when they are exposed to external stimulation such as bending and pressing. The birefringence of the LCP/LC in a flexible display device was measured as a function of bending or pressing deformation. The microscopic dynamic behavior of main chain, side chain, and the LC were characterized by FTIR and polarization optical microscopy. When the device is deformed in scattering memory state, liquid crystal(LC) director is found to align from randomly oriented domain state(scattering state) to homeotropic state.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.450-452
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• 2005

The ion beam alignment technique is one of the potential and fascinating methods. However, there are merely a few reports about aligning nematic liquid crystals (NLCs) horizontally for in-plane switching mode (IPS) by means of low energy ion beam exposure on inorganic materials such as DLC. In this study, we have investigated the tilted vertical alignment of NLC by the ion beam technique on the thin films of various amorphous silicon compounds as new inorganic alignment materials. Appropriate pretilt angles of NLC with preferred orientation on these thin films were achieved. And the electro-optic property of vertically aligned single domain cells has been investigated.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.330-333
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• 2005

We investigated the liquid crystal (LC) alignment phenomena using a-C:H and a-C:F:H thin films. Homogeneous alignment is obtained using ion beam treated hydrogenated amorphous carbon (a-C:H) thin films. Homeotropic alignment is obtained using F treated a-C:H thin films, namely, fluorinated amorphous carbon (a-C:F:H) thin films. We investigated the relationship between the surface properties of amorphous carbon based alignment layer and LC alignment phenomena.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.411-414
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• 2005

We have developed a transflective liquid crystal display (LCD) with a single cell gap and a low twisted nematic (LTN) mode in combination with a self-integrated retardation layer. The retardation layer was made of UV curable liquid crystalline material in one step of photo masking process and has both the homeotropic and the planar parts. The proposed transflective configuration has advantages in a simple fabrication process, and the possibility for a single driving scheme due to the similarity between the transmittance and the reflectance.

• Journal of Information Display
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• v.5 no.1
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• pp.34-40
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• 2004

Time resolved infrared IR absorption spectroscopy is carried out to investigate the dynamics of electric field induced reorientation of the biphenyl molecular core and alkyl tail sub-fragments of the nematic liquid crystal 5CB (4-pentyl-4-cyano-biphenyl). The planar to homeotropic transition for high pre-tilt planar aligned cells, is studied for switching times ranging from 200 ${\mu}sec$ down to 80 ${\mu}sec$, the latter a factor of 1000 times faster than any previous nematic IR study. The reorientation rates of the core and tail are found to be the same to within experimental error and scale inversely with applied field squared, as expected for the balance of field and viscous torques. Thus any molecular conformation change during switching must relax on a shorter time scale. A simple model shows that no substantial differences exist between the reorientational dynamics of the tails and cores on the time scales longer than on the order of 10 ${\mu}s$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.8
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• pp.670-674
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• 2001

The electro-optical (EO) performance in the vertical-alignment (VA) - 1/4$\pi$ cell photoaligned with polarized UV exposure on a homeotropic photopolymer surfaces was investigated. Excellent voltage-transmittance curve in the VA - 1/4$\pi$ cell photoaligned with polarized UV exposure for 3 min on the photopolymer containing cholesteryl group of 8% can be achieved. The V-T characteristics in the VA-1/4$\pi$ cell photoaligned on the photopolymer surface can be improved by increasing cholesteryl group. For response time measurement, the transmittance characteristics of the VA-1/4$\pi$ cell photopolymer surface was better than that of the VA-1/4$\pi$ cell rubbingaligned on a polyimide(PI) surface.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.4
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• pp.332-336
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• 2000

We have developed a novel vertical-alignment(VA) -$\pi$ cell mode that provides a wide viewing angle and fast response times for nematic liquid crystal(NLC) with negative dielectric anisotropy on a homeotropic polymide(PI) surfaces. Good voltage-transmittance curves and low driving voltages were achieved with the new VA-$\pi$ cell mode without a negative compensation film. Iso-viewing angle characteristics using the new VA-$\pi$ cell mode without a negative compensation film was also successfully observed. As well a fast response time of 31.7 ms for a new VA-$\pi$ mode was measured. Consequently the iso-viewing angel fast response time and low driving voltage characteristics using a VA-$\pi$ cell can be achieved.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.8
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• pp.700-703
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• 2000

We investigated the improvement using a new patterned double twisted(PDT) vertical-alignment(VA) cell mode on a homeotropic alignment layer. Good voltage-transmittance curves for negative dielectric anisotropic nematic liquid crystal (NLC) using a new PDT-VA cell without a negative compensation film were obtained. The viewing angle of a new PDT-VA cell without a negative compensation film was sider than that of a conventional VA cell. Finally a few fabrication processes using a new PDT-VA cell mode can be achieved by only one-side rubbed substrate.