Effect of 2+2 dynamic drive scheme on electro-optical characteristics in cholesteric liquid crystal displays
We have developed and extended the basic idea of 2+2 dynamic driving scheme (DDS) for a VGA (640480) panel and optimized it to show the ONOFF switching characteristic. The temperature dependence of selection time of 2+2 DDS is similar with that of 3+2 DDS. The position dependence upon pre and post selection is serious and not suitable for driving the panel. We found that two steps of a propagation period provide the most stable homeotropic state and ONOFF switching system. With this new driving scheme the potential gray scale for Ch-LCD in a 640480 pixels matrix was examined. The gray scale can be obtained at a relatively higher voltage. We obtain 32 gray numbers and above 20 potential grays with 40V of Vpeak and 1.2ms/line of scan driving time in the VGA panel. Our 2+2 DDS may be useful for foldable display applications, such as for electronic paper.
dynamic driving scheme (dds) gray scale cholesteric liquid crystal display (ch-lcd) bistable lcd