• Polymer(Korea)
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• v.35 no.5
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• pp.385-389
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• 2011

In rubbing process, process factors, the properties of alignment layer and the physical properties of rubbing cloth have acted as important variables. These factors affect the orientation properties of the alignment layer by rubbed extent that is determined by rubbing density and rubbing force. In this work, we studied the effects of rubbing cloths with different pile density and rigidity on rubbing density(length) and rubbing force. As the pile density and rigidity of rubbing cloths increased, the birefringence and the surface roughness of the rubbed alignment layers became bigger, but the characteristics of rubbing-effect had differed each other. The pile density of rubbing cloths which was related with the number of pile, affected the rubbing density(length). On the other hand, the pile rigidity of rubbing was closely related to rubbing force rather than the rubbing density(length).

• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1577-1578
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• 1997

We have studied the effect of the rubbing fabric for liquid crystal alignment and pretilt angle generation in nematic liquid crystals (NLC), 4-cyano-4-n-penthylbiphenyl (5CB), on rubbed polyimide (PI) surfaces. The pretilt angle of 5CB for nylon and rayon fabric is larger than that of cotton fabric in weak rubbing on rubbed PI surfaces. We conclude that the pretilt angle of 5CB is strongly related to the rubbing fabrics on rubbed PI surfaces.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1319-1321
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• 2009

Copper phthalocyanine (CuPc) Field-effect transistors (FETs) was successfully fabricated on plastic substrates. Orientation of CuPc crystallites on substrate could be obtained via rubbing process. It was revealed that CuPc crystallites were perpendicularly aligned on PES substrates with the rubbing direction. The performance of FETs was affected by orientation of CuPc on rubbed substrates.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1603-1605
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• 1996

We have studied the static electricity and optical retardation generated by rubbing the surfaces of polyimide (PI) and polyamide (PA) films. The static electricity increases with the rubbing strength (RS) and varies with the different PI films. We also investigated how the differences in the rubbing fabric affects the magnitude of the induced static electricity; the order of this effect is nylon > rayon > cotton. The induced static electricity is not only directly related to the values of the specific resistivity of the rubbed PI films, but also the RS and the ability of the rubbing fabric to generate and add a static electric charge. The order of the optical retardation produced by the rubbing fabraic on rubbed PI films is nylon > rayon > cotton, coinciding with the order of the generated static electricity.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1815-1817
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• 1999

In this paper, the generation of high pretilt angle in nematic liquid crystal (NLC) by dipping effect on three kinds of the rubbed polyimide (PI) surface was investigated. The generated pretilt angle of NLC increases due to dipping effect before rubbing treatment on two kinds of the rubbed PI surface with side chain. The generated pretit angle in NLC by using dipping effect after rubbing treatment on PI surface with short side chain is high compared to the PI surface with long side chain. The generated pretit angle of the positive type NLC $(\Delta{\varepsilon}>0)$ is higher as than that of the negative type NLC $({\Delta}{\varepsilon}<0)$ by using dipping effect before rubbing treatment on homeotropic layer. The generated pretilt angle of NLC is attributed to perpendicular component of permittivity ${\varepsilon}_{\perp}$ of NLC on rubbed PI surface.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.330-330
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• 2008

It is widely investigated to liquid crystal (LC) alignment using non-contact alignment method such as ion-beam (IB) irradiation, UV alignment, and oblique deposition. Because conventional rubbing method has some drawbacks. These include defects from dust and electrostatic charges and rubbing scratch during rubbing process. In addition, rubbing method needs additional process to remove these defects. Therefore rubbing-free methods like ion-beam irradiation are strongly required. We studied LC alignment effect on poly imide surface by IB irradiation and electro-optical (EO) characteristics of twisted nematic liquid crystal display (TN-LCD). In this experiment, a good uniform alignment of the nematic liquid crystal (NLC) with the ion-beam exposure on the polyimide (PI) (SE-150 from Nissan Chemical) surface was observed. We also achieved low pretilt angle as a function of ion-beam irradiation intensity. In addition, it can be obtained the good EO properties of the IB-aligned TN-LCD on PI surface. Some other experiments results and discussion will be included in the poster.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1600-1602
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• 1996

We have investigated the anisotropic dispersion force effects for surfaces alignment of liquid crystals (LCs) on rubbed polystyrene (PS) surfaces by unidirection. In microphotographs an of the textures, we obtained the nematic (N) LCs are shown to align in both direction parallel and perpendicular to the rubbing for region up to medium rubbing, however to align in the direction perpendicular to the rubbing for strong rubbing region. We suggest that the anisotropic dispersion force is very important rather than macro-surface groove effect to uniform alignment of LCs. We also measured the temperature dependence of extrapolation length of 5CB on rubbed PS surfaces for strong rubbing. It is shown that the polar anchoring strength of 5CB is very weak on rubbed PS surface compared to the rubbed polyimide (PI) surface.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.05a
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• pp.105-108
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• 1996

We have studied the anisotropic dispersion force effects for surfaces alignment of liquid crystals (LCs) on rubbed polystyrene (PS) surfaces by unidirection. In microphotographs of the textures, we obtained the nematic (N) LCs are shown to align in both direction parallel and Perpendicular to the rubbing for region up to medium rubbing, however to align in the direction perpendicular to the rubbing for strong rubbing legion. We suggest that the anisotropic dispersion force is very important rather than macro-surface groove effect to uniform alignment of LCs. We also measured the temperature dependence of extrapolation length of 5CB on rubbed PS surfaces for strong rubbing. It is shown that the polar anchoring strength of 5CB is very weak on rubbed PS surface compared to the rubbed polyimide (Pl) surface.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.426-429
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• 2005

The fringe-field switching (FFS) mode associated with a transition from a homogenously aligned to twist deformation require rubbing process. In this devices, $1^o$ of misalignment in an azimuthal direction could cause voltage-dependent transmittance (V-T) to be different from that in a normal area and consequently results in a rubbing mura. According to our studies, the single domain FFS cells are much more sensitive to the rubbing mura than the dual domain FFS cell. Moreover, the FFS cells with negative LC are much more sensitive to the rubbing mura than the FFS cells with positive LC.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.446-449
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• 2005

The alignment property of liquid crystals on the two-easy axes substrate is investigated. The two-easy axes substrate frustrates the orientation of the LCs next to the substrate, and hence influences the birefringence of the LC cell. Experimental findings reveal that the ratio of the rubbing strengths in the different rubbing directions and the cell thickness substantially influence the birefringence of the LC cell. The surface anchoring energetic competition between the different rubbing directions contributes to the observed results.