Abstract
In the TFT-LCD industry, the AF (alignment film) materials using polyimide have been developed in order to minimize the absorption and emission of impurities on the surface of the AF inside the cell liquid crystal. Accordingly, for quality improvement, various approaches for the structural analysis and interpretation of the AF are being required.
In this study, the direct analysis and comparison have been made for the characteristics of AF according to the processing conditions of LCD drive mode. Using AFM/FFM, the friction characteristics of the TN mode and VA mode surfaces according to the temperature conditions have been compared. Although the friction asymmetry in rubbing direction has been detected according to the temperature conditions in the TN mode, it did not appear in case of the VA mode. This has been interpreted as being due to the intermolecular repulsion by the density of side chain. For the IPS mode AF which does not form the side chain, whether the double-layer would be formed according to the Pre-bake conditions and the Image Sticking effect according to it have been arranged.
Through the measurement using LCM-3 (Toyo Corporation) on the real panel, the cross-matching results for the Ion Density, image sticking and VHR have been compared and analyzed. As a result, the Image Sticking level was found to become higher as the Ion Density inside the liquid crystal increases, and the correlation coefficient with VHR was also found to be high. The ion density has been confirmed as the significant factor of persistence.
