Novel Pretilt Angle Measurement Method for Twisted-Nematic Liquid-Crystal Cells by Apparent Retardation Measurement

We have proposed a novel pretilt angle measurement method for twisted-nematic (TN) liquid-crystal (LC) cells. In this method, the dependence of the apparent retardation of the TN cell on the cell rotation angle is analyzed by the simple mathematic equations derived here to determine the pretilt angle and the gap. This method can be applied to the TN LC display panel. The necessary range of the cell rotation angle is from -3° to 3°. This provides an advantage for both constructing a compact measurement system and measuring a small-size pixel.