Study of line filling process for flexible cholesteric liquid crystal cell

• Main Authors: Che-Cheng Liu, 劉哲誠
• Other Authors: Wen-Tuan Wu
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/60681946110626367831

碩士 === 南台科技大學 === 光電工程系 === 97 === The glass substrate is the main material used in current LCD display. Flexible display shows the potential application for next generation of display application, because the plastic material has the advantages on the weight and flexibility. Moreover, flexible displays can be designed for various electronic products such as electronic book, electronic paper and electronic board etc. At any aspects, the plastic substrate will substitute the glass material, and then leads the process evolution from sheet-feed Batch process to Roll-to-Roll process. In this study, we fabricated the flexible cholesteric liquid crystal cell by using a roller pressing unit to laminate two PET substrates. Cholesteric liquid crystal had high viscosity, so that the flowability was limited. Therefore, it had high percentage to form bubbles in the cell. In order to enhance the surface energy and wetability properties and reduce bubbles in the cell, we use O2 plasma to modify the surface of ITO coated PET substrate. The influence of treatment on the surface properties of PET were investigated by contact angle and atomic force microscopy (AFM). Experimental results revealed that the cell formed from the untreated substrate had bubbles at substrate speed of 5mm/sec. This result is attributed to the poor wetability and low surface energy. However, adding external load can enhance the substrate lamination speed. In contrary to the untreated substrate, O2 plasma treated substrates had good wetability and high surface energy so that it could improve the anchoring of liquid crystal on the surface. At the speed of 30mm/sec, there was no bubble in the cell. As the lamination speed was increased, the external load was the key factor to influence the flowability of LC. Under the optimized condition, the substrate lamination speed would reach 40mm/sec. The cell had good optical property with O2 plasma treated surface and the cell deviation of reflectance could be minimized.