Scan driving method for rendering high-contrast image and cholesteric liquid-crystal display device using the same

Abstract

A cholesteric liquid-crystal display device is provided, which includes a liquid crystal display panel. The liquid crystal display panel includes a first substrate, a second substrate, a cholesteric liquid crystal layer, and a driving circuit. The first substrate includes a plurality of scanning electrodes extending in a first direction. The second substrate includes a plurality of data electrodes extending in a second direction different from the first direction. The cholesteric liquid crystal layer is formed between the first substrate and the second substrate. The driving circuit is configured to apply a plurality of alternative-current (AC) voltage pulses to pixel circuits at intersections between the scanning electrodes and data electrodes. A modified pulse-width modulation (PWM) scanning procedure of the pixel circuits on each scanning electrode sequentially activated by the driving circuit section comprises a first stage, a second stage, and a third stage arranged in sequence. The first stage is configured to manipulate grayscale values of the pixel circuits on a first scanning electrode among the plurality of scanning electrodes to be written in the second stage. When the pixel circuits on the first scanning electrode are within the first stage, the pixel circuits on the remaining scanning electrodes, which are within a first period of the third stage, sense a zero voltage, wherein the first period corresponds to a high-voltage period within the first stage of the pixel circuits on the first scanning electrode.

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