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

A scan driving method for rendering a high-contrast image, for use in a cholesteric liquid-crystal display device, the cholesteric liquid-crystal display device comprising a display panel and a driving circuit section, wherein the display panel comprises a plurality of scanning electrodes and a plurality of data electrodes, the method comprising:

• utilizing the driving circuit section to sequentially activate each scanning electrode within the display panel using a modified pulse-width modulation (PWM) scanning procedure, which comprises a first stage, a second stage, and a third stage in sequence;
• and
• utilizing the driving circuit section to apply one or more alternating-current (AC) voltage pulses to pixel circuits on a first scanning electrode among the plurality of scanning electrodes during the first stage of each pixel circuit on the first scanning electrode to manipulate grayscale values of the pixel circuits on the first scanning electrode to be written in the second stage,
• wherein 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.

A cholesteric liquid-crystal display device, comprising:

• a liquid-crystal display panel, comprising:
• a first substrate on which a plurality of scanning electrodes extending in a first direction are formed;
• a second substrate on which a plurality of data electrodes extending in a second direction different from the first direction are formed;
• a cholesteric liquid crystal layer formed between the first substrate and the second substrate;
• and
• a driving circuit section, configured to apply a plurality of alternating-current (AC) voltage pulses to pixel circuits at intersections between the scanning electrodes and the data electrodes,
• wherein the driving circuit section is configured to activate each scanning electrode sequentially using a modified pulse-width modulation (PWM) scanning procedure which comprises a first stage, a second stage, and a third stage arranged in sequence,
• wherein when the driving circuit section activates a first scanning electrode among the plurality of scanning electrode, the first stage of each pixel circuit on the first scanning electrode is configured to manipulate grayscale values of each pixel circuit on the first scanning electrode to be written in the second stage,
• wherein when a bright-state voltage is applied to the pixel circuits on the first scanning electrode during the first stage, the pixel circuits on the remaining scanning electrodes, which are within the third stage, sense a voltage substantially equal to a zero voltage or close to the zero voltage.