• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.16 no.11
• /
• pp.1014-1018
• /
• 2003

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

• Proceedings of the KIEE Conference
• /
• 1999.07d
• /
• pp.1765-1767
• /
• 1999

We synthesised a photo-alignment material of PM4Ch (poly(4-methacryloylloxychalcone)). The electro-optical (EO) characteristics of photo-aligned twisted nematic (TN)-liquid crystal display (LCD) with linearly polarized ultraviolet (UV) light irradiation on PM4Ch surface were investigated. The uniform alignment of NLC with polarized UV light irradiation on PM4Ch surface was measured. Also, We had The excellent voltage-transmittance characteristics of photo-aligned TN-LCD. The low threshold voltage of photo-aligned TN-LCD was measured. Moreover, the fast response time of photo-aligned TN-LCD on PM4Ch was successfully achieved. Finally The reduction DC voltage of photo-aligned TN-LCD decreases with increasing the UV light irradiation time on photo-dimerized PM4Ch surface.

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

• Bulletin of the Korean Chemical Society
• /
• v.23 no.4
• /
• pp.587-592
• /
• 2002

Photocrosslinkable chalcone-epoxy compound comprising 1,3-bis-(4-hydroxy-phenyl)-propenone was synthe-sized for fabricating the photo-alignment layer of liquid crystals. Chalcone group was introduced into the main chain unit of the epoxy oligomer. We observed a photodimerization behavior and an optical anisotropy of this material by irradiation of a linearly polarized UV(LP-UV) light. With a trace amount of cationic photoinitiator (TRS-HFA), polymerization of epoxy groups was also conducted at the similar wavelength range used for photodimerization. Linearly polarized UV irradiation on the chalcone-epoxy films with cationic photoinitiator induced optical anisotropy of the film and the resultant film can be used for alignment layers for low molecular weight nematic liquid crystals.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.11a
• /
• pp.583-585
• /
• 2004

In this paper, we synthesized a new photo-crosslinkable polyitaconimide containing cinnamoyl moiety by radical polymerization. Also, the NLC alignment capabilities on these photopolymer surfaces were studied. Good LC alignment with W exposure on the polyitaconimide surfaces can be obtained. A homogenous alignment using UV exposure on the polyitaconimide with 1-carbon chain cinnamoyl group and 4-carbon chain cinnamoly group can be obtained. However, the homeotripic alignment using UV exposure was observed on polyitaconimide with 6-carbon chain cinnamoyl. The LC aligning ability on the polyitaconimide depends on the side chain length of photopolymer.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.14 no.4
• /
• pp.336-340
• /
• 2001

We have investigated the generation of pretilt angle and alignment stability for a nematic liquid crystal (NLC) with obliquely polarized UV exposure on the three kinds of photo-polymer. High pretilt angle of the NLC was obtained by polarized UV exposure on a PM4Ch surface for 1 min. But, the low pretilt angle of he NLC on a PVCi surface was observed. The pretilt angle generated is attributed ot the photosensitivity by the long side chaining of photo-polymer. Also, a good thermal stability of the three kinds of photo-polymer were obtained by thermogravimetric analysis (TGA) measurement until 300$^{\circ}C$. Finally, the good LC aligning capabilities using the photodimerization method were observed by annealing-treatment until 150$^{\circ}C$.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2008.10a
• /
• pp.317-319
• /
• 2008

Photo-alignment layer which contains cinnamate is difficult to generate pretilt angle of liquid crystals. In order to enhance pretilt angle, blending poly (amic acid) between containing fluorine poly (amic acid) and 1,2,3,4-cyclobutanetetracaroxylic dianhydride (CBDA) / 3,5-diaminobenzyl alcohol (DBA) were used. For photoreaction, cinnamate was conjugated by interfacial reaction with blending polyimide.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.05a
• /
• pp.223-223
• /
• 2004

반도체 및 TFT LCD 제조 공정에서 핵심 공정인 Photo 공정은 PR(Photo Resist, 감광액) Coating -) Exposure(노광) -. Develop(현상)으로 이루어져 있다. 이중 Exposure 공정에 사용되는 장치가 노광장비이다. 노광장비는 Mask Aligner 라고도 불리는데, 그만큼 정렬기술이 노광장비에서는 중요하다. 반도체 및 TFT LCD 는 여러 충의 회로를 쌓아감으로써 층과 층간의 전기적 작용으로 생성되는 Tr.(Transistor) 또는 Diode 등의 수동소자를 집적하는 기술로 제조되는 것으로, 층과 층간의 전기적 작용이 설계한 바와 같이 이루어지기 위해선, 층과 층 사이의 정렬이 정확히 이루어져야 한다.(중략)

• Journal of Korean Vacuum Science & Technology
• /
• v.6 no.1
• /
• pp.1-4
• /
• 2002

A simple method for real-time monitoring the molecular orientation in a polymeric film was suggested. This method was examined in the polarization holograms by two recording beams on a poly(malonic ester) containing disperse red 1. The spatial distributions of the photo-induced alignment were measured and analyzed at various polarization states of two recording beams. As the result, the directions of molecular alignments could be identified easily by our method.

• Proceedings of the KIEE Conference
• /
• 1999.07d
• /
• pp.1762-1764
• /
• 1999

We investigated the annealing effect on generating pretilt angle and aligning liquid crystal (LC) using the photo-depolymerization reaction in this study. In case of rubbing polyimide (PI) surface with the side chain, pretilt angle tends to increase with increasing the annealing time. It is considered because the steric interaction is increased by annealing which cause the side chain to come back to original position. For obliquely irradiating ultraviolet (UV) light on PI surface, pretilt angle shows to $0^{\circ}$ and is increased by annealing. The pretilt angle in rubbed PI surface is much higher than in photo-aligned PI surface. It is attributed to the steric interaction and the number of LC molecular arrangement on azimuthal direction. In addition. in case of obliquely irradiating UV light on PI surface. it showed LC alignment to increase by annealing. It can be regarded due to the fact that the re-alignment of LC molecule is improved to residual polymer direction by annealing.