Writable Cholesteric Liquid Crystal Display and the algorithm used to detect its image were developed. We could use any hard tip, ex: the tip of a forefinger, to directly write an image on the surface of Cholesteric Liquid Crystal Display (CHLCD). By measuring the capacitance of one pixel of test cell (12mm × 15mm/ 1×1), F-state or P-state could be detected. By measuring the capacitance of one pixel of 4.1″ CHLCD (241um × 241um/ 320×320), F-state or P-state could not be detected, due to the effect of parasitic capacitance. Therefore, high frequency measurement and the algorithm were developed to detect the image on CHLCD.
