• Transactions on Electrical and Electronic Materials
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• v.8 no.1
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• pp.46-50
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• 2007

We have studied the nematic liquid crystal (NLC) alignment effects on a nitrogen-doped diamond-like carbon (NDLC) thin film layer with ion beam irradiation. The pretilt angle for NLC on the NDLC surface with ion beam exposure was observed below 1 degree. Also, we had the good LC alignment characteristics on the NDLC thin films with ion beam exposure of 1800 eV. In thermal stability experiments, the alignment defect of the NLC on the NDLC surface with ion beam irradiation above annealing temperature of $250^{\circ}C$ can be observed. Therefore, the good thermal stability and LC alignment for NLC by ion beam aligned NDLC thin films can be achieved.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.1114-1117
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• 2004

We investigated the liquid crystal (LC) alignment phenomena using hydrogenated amorphous carbon (a-C:H) thin films. For LC alignment, the surface of a-C:H thin films is treated with low energy ion beam. We investigated the relationship between the properties of a-C:H thin films and LC alignment phenomena.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.04a
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• pp.116-119
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• 1997

We investigated new type non-robbing liquid crystal (LC) alignment techniques in the cell with slanted non-polarized ultraviolet (UV) irradiation on polyimide (Pl) film. It is shown that the uniform alignment for nematic (N) LC is obtained by using slanted non-polarized UV irradiation on Pl surface. We successfully obtained that the pretilt ang1e of NLC is generated about 3 degree in the LC cells by using slanted non-polarized UV irradiation with 70 degree on Pl surface. We consider that the pretilt angle generation for NLC is attributed to interaction between the LC molecular and the PI surface. We conclude that the uniform LC alignment is attributed to anisotropic dispersion force effect due to photo depolymerization of polymer on Pl surface.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.489-492
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• 2003

Photoalignment materials of PGMAcr, poly[3-(acryloyloxy)-2-hydroxypropyl methacrylate] using an acrylate unit photopolymerized by a photo-initiator and PGMA4Ch, poly[3- (4-ehalconyloxy)-2-hydroxypropyl methacrylate] using photodimerization by the chalcone group were synthesized. Also, the liquid crystal (LC) alignment capabilities on the photopolymer layers were studied. A good LC alignment with UV exposure on the PGMAcr surface can be obtained. However, LC alignment defects were observed on the PGMA4Ch surface. The LC alignment capability of the PGMAcr surface by the photoinitiator was better than that of the PGMA4Ch surface by the chalcone group which is a photosensitive moiety.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.8
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• pp.866-870
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• 2004

We have investigated the generation of pretilt angle for a nematic liquid crystal (NLC) alignment with rubbing alignment method on polyimide surfaces using plastic substrates. It was found that monodomain alignment of NLC is obtained with rubbing alignment method on polyimide surfaces using thin plastic substrates. The NLC pretilt angles on thin plastic substrates generated higher than that on glass substrate. Also, EO characteristics of the TN-LCD with a rubbed PI surface based on polymer substrate are almost the same as that of the TN-LCD with a rubbed PI surface based on glass. However, the transmittances of the TN-LCD with a rubbed PI surface based on polymer is less than that with a rubbed PI surface based on g1ass.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.999-1002
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• 2003

Electrooptical (EO) characteristics of a new multidomain vertical-alignment (MVA) liquid crystal display (LCD) with negative dielectric anisotropy on a homeotropic photopolymer were studied. Good voltage-transmittance (V-T) curves of the new MVA-LCD on the homeotropic photopolymer were obtained. Also, the stable response time of the new MVA-LCD on the homeotropic photopolymer was achieved. The viewing angle of the new MVA-LCD could be improved by a crossed stripe grating-groove surface as the alignment layer using a photolithograph method on the photopolymer.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.9
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• pp.770-775
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• 2000

A new photo-polymer material of the copoly (PM4Ch-ChMA), copoly (poly (4-methacryloyloxy)chalcone-cholesteryl methacrylate) for homeotropic alignment was synthesized and the electro-optical (EO) performance for the photo-aligned vertical-aligned (VA)-LC display (LCD) was studied. Good thermal stabilities of synthesized copolymer were obtained by TGA(Thermogravimetric Analysis) measurement. Good voltage-transmittance (V-T) and response time characteristics for the photo-aligned VA-LCD with polarized UV exposure in oblique direction($\theta$$_{i}$=30$^{\circ}$) on a copolymer-1 (2%) surfaces for 1 min were observed. but, light leakage in the off-state was observed. Therefore, we achieved excellent V-T and response time characteristics for the photo-aligned VA-LCD with UV exposure on a copolymer-3 (30%) surfaces for 3 min.n.

• Transactions on Electrical and Electronic Materials
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• v.5 no.1
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• pp.15-18
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• 2004

We studied the nematic liquid crystal (NLC) aligning capabilities using the new alignment material of a-C:H thin film by plasma enhanced chemical vapor deposition (PECVD) system for 30 sec under 30W rf power at a gas pressure of 1.4＊10$\^$-1/ torr. A high pretilt angle of about 5 by ion beam exposure on the a-C:H thin film surface was measured. A good LC alignment by the ion beam alignment method on the a-C:H thin film surface was observed at annealing temperature of 250$^{\circ}C$, and the alignment defect of NLC was observed above annealing temperature of 300$^{\circ}C$. Consequently, the high LC pretilt angle and the good thermal stability of LC alignment by the ion beam alignment method on the a-C:H thin film by PECVD method as working gas at 30W rf bias condition can be achieved.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.939-942
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• 2004

In this study, we report simulation results of single-panel LCOS (liquid crystal on silicon). Reflective LCOS microdisplays are widely used in various projection and near-eye application. For one panel system, liquid crystal response time is an important variable. The panel must switch fast enough to support the display of Field color sequential with high field rates. In order to have fast response and good contrast, a vertical alignment (VA) cell was used in this study. With suitable selection on LC parameters like temperature, viscosity, elastic constant and birefringence, it is possible to get response time of around 2ms from a 2.0 um-thick vertical alignment cell. This result also indicates an ease of production control on 2.0 um cells than 1.0 um cells.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.193-197
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• 2004

The effect of the temperature dependence of the smectic layer spacing in the smectic-A (SmA) phase on the formation of defects in the ferroelectric smectic-$C^{\ast}$ ($SmC^{\ast}$) phase is investigated with x-ray scattering technique. The study is based on thin parallel-aligned surface stabilized ferroelectric liquid crystal cells with two different alignment conditions, high pretilt $SiO_x$, alignment and low pretilt polyimide films. It is found that defects observed in the $SmC^{\ast}$ phase have much more profound dependence on the layer changes and chevron formation in the SmA phase than in the $SmC^{\ast}$ phase. We find that thermal layer expansion with decreasing temperature in the SmA phase suppresses the formation of defects observed in the SmC phase.