• 한국정보디스플레이학회:학술대회논문집
• /
• 2007.08a
• /
• pp.506-508
• /
• 2007

We studied the nematic liquid crystal (NLC) alignment capability with a new alignment method utilizing an inkjet printed polyimide (PI) layer. A good, uniform LC alignment was achieved by the good PI printing using a new alignment method. The pretilt angle generated on the printed PI layer using the alignment method was almost the same as that on printed PI layer using rubbing alignment method. In addition, the good electro-optical performances of the new aligned twisted nematic (TN) cell with printed PI surface was obtained

• Journal of Information Display
• /
• v.10 no.4
• /
• pp.180-183
• /
• 2009

A stamping-assisted rubbing technique for generating bidirectional alignment in the fabrication of wide-viewing twistednematic (TN) liquid crystal displays (LCDs) was developed. A patterned layer of a fluorinated acrylate polymer was transferred onto the first rubbed alignment layer prepared on a substrate by stamping. The fluorinated acrylate polymer provides a protective layer that covers the first alignment layer during the second rubbing process to facilitate the bidirectional alignment of the LC molecules. The LC cell in the twisted geometry with two bidirectional-alignment layers showed stable electro-optic properties and wide-viewing characteristics. The stamping-assisted rubbing technique serves as a mask-free alignment method of producing multidomains for wide-viewing LCDs.

• Journal of Information Display
• /
• v.12 no.4
• /
• pp.191-194
• /
• 2011

A symmetric-viewing inverse-twisted-nematic (ITN) liquid crystal display (LCD) with alternating alignment layers was developed using a stamping-assisted rubbing (SAR) technique. A patterned layer of a fluorinated acrylate polymer was transferred onto the first rubbed vertical-alignment layer prepared on a substrate by stamping. The fluorinated acrylate polymer provided a protective layer covering the first rubbed alignment layer during the second rubbing process, which promoted the vertical alignment of the LC molecules. The LC cell in the ITN geometry with two orthogonally rubbed alignment layers showed symmetric-viewing characteristics with fourfold symmetry. The SAR technique was shown to be a mask-free alignment method of producing multidomains for symmetric-viewing LCDs.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2009.10a
• /
• pp.672-676
• /
• 2009

Polymide is widely used alignment material of recent commercial LCD panel structure. Generally, polyimide alignment material is classified soluble polyimide type and polyamic acid type with their main bond structure of solution state. specially, compared to polyamic acid alignment layer, soluble polyimide type alignment layer have excellent reliability during long term LCD driving cause of their high imidazation ratio(%), high voltage holding ratio(%) and low ion density. The other side, this type alignment materials has significant DC image stickicng side effect for using in-plane switching mode lcd structure cause of their slow DC discharging property. we applied inorganic salt to usual soluble polyimide type alignment layer and found out this technique had good DC image sticking property without any loss of reliability property in inplane switching LCD cell structure. This approach leads excellent DC image sticking property with maintaining high reliability property this approach confirmed improves an image sticking and a reliability simultaneously from the horizontality aligned LCD mode whose relatively bad image sticking property.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2005.07a
• /
• pp.472-475
• /
• 2005

The electrical performances of liquid crystal (LC) cells with chloromethylated polyimide (CMPI) alignment layers were investigated. The CMPI layer was previously reported as a multifunctional layer that does role of LC alignment and planarization layer as well as photo-alignment material with high photosensitivity and excellent thermal stability. The capacitance-voltage (C-V) characteristics of LC cells with CMPI alignment layers were measured. Mechanical rubbing of the CMPI layer did not generate much difference in residual DC when compared to commercial PI. However, the LC cell with photo-oxidation CMPI layer shows a high residual DC value and a corresponding low voltage holding ratio (VHR) due to the photo-induced ionic charges on the alignment layer.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.26 no.9
• /
• pp.677-681
• /
• 2013

Apart from the deposition of alignment layer, alignment process needs to be involved for alignment of liquid crystal (LC) molecules. To simplify manufacturing process, several method were used such as rubbing, ion-beam irradiation, UV irradiation, and lithography. But, eventually it needs another treatment for LC alignment. Here, we suggested Si induced polyimide (PI) alignment layer at low temperature. Using this method, we are able to eliminate the alignment process and found that the alignment and electro-optic performance are much better than that of the rubbed PI LC cells. Compared to the rubbed PI cells, the response time was decreased by 70% and C-V characteristics have hysteresis-free.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.35 no.1
• /
• pp.58-65
• /
• 2022

The field of liquid crystal display (LCD) is constantly in the spotlight and the process of depositing an alignment layer in the LCD manufacturing process is very important to obtain excellent performance such as low-power driving and high-speed response to improve LCD performance. Therefore, research on liquid crystal (LC) alignment is being actively conducted. When manufacturing LCD, it is necessary to consider the effect of the alignment layer thickness as one of the factors affecting various LCD performances. In addition, previous studies confirmed the LC alignment characteristics correlate with the rotation speed in the spin coating process. Therefore, the electro-optical properties of the LCD were investigated by manufacturing a polyimide alignment layer by varying the rotation speed in the spin coating process in this study. It was confirmed that the thickness of the polyimide alignment layer was controlled according to the spin coating conditions. The average transmittances of anti-parallel LC cells at the spin coating speed of 2,500 rpm and 3,000 rpm are about 60%, which indicates that the LC cell has relatively higher performance. At the spin coating speed of 3,000 rpm, the voltage-transmittance curve of twisted nematic (TN) LC cell was below 1.5 V, which means that the TN LC cell operated at a low power. In addition, high-speed operating characteristics were confirmed with a response time of less than 30 ms. From these derived data, we confirmed that the ideal spin coating speed is 3,000 rpm. And these results provide an optimized polyimide alignment layer process when considering enhanced future LCD manufacturing.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2009.10a
• /
• pp.668-671
• /
• 2009

Photosensitive polyimide containing methoxy cinnamate derivatives as a photo-alignment layer is investigated. The anisotropy of alignment layer was induced by irradiation linearly polarized UV (LPUV). We studied the effect of the methoxy cinnamate groups on alignment LCs.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.18 no.11
• /
• pp.1028-1032
• /
• 2005

Liquid crystal (LC) alignment using a photoalignment method by irradiation of polarized ultraviolet (UV) on an alignment layer has been investigated. Photoalignment method exhibits weaker anchoring energy than rubbing method so that we have studied electro-optic characteristics of fringe-field switching (FFS) mode with alignment layers using the photo and rubbing alignment methods. The cell using photo alignment layer shows lower threshold and operation voltage than those using rubbed alignment layer. Also, the former method shows higher transmittance than that of the latter.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2005.05a
• /
• pp.118-122
• /
• 2005

Liquid crystal (LC) alignment using a photoalignment method by irradiation of polarized ultraviolet (UV) on an alignment layer has been investigated. Photoalignment method exhibits weaker anchoring energy than rubbing method so that we have studied electro-optic characteristics of fringe-field switching (FFS) mode with alignment layers using the photo and rubbing alignment methods. The cell using photo alignment layer shows lower threshold and operation voltage than those using rubbed alignment layer. Also. the former method shows higher transmittance than that of the latter.