The influence of backflow on the switching speed of dual frequency liquid crystal

Backflow is a well-known effect that limits the switching speed in vertical aligned liquid crystal displays. When voltages are applied exceeding a certain threshold voltage, the reorientation which is initially fast causes a flow that influences the director orientation in the middle of the cell. An optical bounce occurs as the liquid crystal in the middle of the cell temporally has a reverse orientation. Driving voltages should thus not exceed this threshold voltage or the switching speed (drastically) reduces [1]. Backflow also increases the relaxation time of cells with planar (or hybrid) alignment but optical bounces do not occur in this situation because the switching to the planar state is typically quite slow as it is driven by the interplay of elastic forces and boundary conditions.