Patent ID: 7145538

Claim:
A method for driving a liquid crystal display by applying AC pulses to a liquid crystal layer, which comprises liquid crystal which exhibits a cholesteric phase having a selective reflection characteristic, through a plurality of scan electrodes and a plurality of data electrodes, in which the scan electrodes are selected for scanning successively at specified time intervals, and an image is formed on the liquid crystal display by switching liquid crystal between a focal-conic state and a planar state, said method comprising: a reset step of applying a reset pulse, which is to reset liquid crystal of the liquid crystal layer to a homeotropic state, to an area of the liquid crystal layer that corresponds to a selected one of the scan electrodes; a selection step of applying a selection pulse, which is to select a final state of the liquid crystal, to the area of the liquid crystal layer after the reset step, said final state of the liquid crystal being either a focal-conic state or a planar state; and an evolution step of applying an evolution pulse, which is to cause the liquid crystal to evolve to the selected final state, to the area of the liquid crystal layer; wherein, a pulse applied to the selected one of the scan electrodes during the reset step has an amplitude which is larger than a maximum amplitude of pulses applied to each of the data electrodes and has a polarity maintaining period of a single plus/minus cycle which is longer than that of a single plus/minus cycle of a pulse applied to the selected one of the scan electrodes during the selection step; a pulse applied to the selected one of the scan electrodes during the evolution step has a polarity maintaining period of a single plus/minus cycle which is longer than that of a single plus/minus cycle of the pulse applied to the selected one of the scan electrodes during the selection step; and a maximum amplitude of the pulses applied to each of the data electrodes is lower than a threshold to change the state of the liquid crystal.