Investigation of the interaction between rubbing cloth and pattern structure on in‐plane‐switching liquid‐crystal displays

Abstract— For the rubbing process, there have been several problems, especially scratching, disclination, and light leakage that increases the black luminance of a panel because the alignment of the liquid crystals might not be uniform due to a fluctuation in the fine‐rubbing direction. To investigate the basic causes of these problems, several experiments concerning the characteristics of the rubbing cloth and the pattern structures on an LCD substrate were carried out. A new mechanism regarding the interaction between the rotation of filaments on the rubbing cloth and the structure of patterns on the IPS‐LCD substrate is proposed. There is a correlation between the filament's rubbing direction and the pattern angle of the substrate. A new rubbing method based on two types of rubbing cloths were introduced to improve the rubbing density. As a result, it was determined that the black luminance was relatively reduced by using this method compared with that of conventional rubbing processes.