Cholesteric liquid crystal display device and method for driving cholesteric liquid crystal display device
Patent Information
- Application Number
- JP2024086163
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2024-04-10
- Filing Date
- 2024-05-28
- Publication Date
- 2025-08-22
Smart Images
Figure 00000000_0000_ABST
Abstract
Claims
1. A cholesteric liquid crystal display device including a liquid crystal display panel, The liquid crystal display panel is a first substrate on which a plurality of first electrodes extending in a first direction are formed; a second substrate on which a plurality of second 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; a drive circuit configured to apply a plurality of alternating current (AC) voltage pulses to pixel circuits at intersections of the first and second electrodes; Including, a pulse width modulation (PWM) scanning procedure of the pixel circuits of the activated first electrodes, comprising a first stage and a second stage; the first stage being configured to accelerate the pulse width modulation scanning procedure of the second stage to write data to the pixel circuits of the activated first electrodes; Cholesteric liquid crystal display.
2. the AC voltage pulses in the first and second stages have first and second voltage amplitudes, respectively; the first voltage amplitude is different from the second voltage amplitude; the first voltage amplitude is equal to a voltage amplitude in a homeotropic state of cholesteric liquid crystal molecules in the cholesteric liquid crystal layer; the second voltage amplitude is lower than the first voltage amplitude; the pulse width modulation scanning procedure further includes a third stage for manipulating the grayscale values of the pixel circuits written in the second stage; the third stage, the first stage, and the second stage are arranged in sequence; 2. The cholesteric liquid crystal display device according to claim 1.
3. the third stage includes an active region and a sleep region; the AC voltage pulses in the operating region and the sleep region of the third stage have third and fourth voltage amplitudes, respectively; the first voltage amplitude is higher than the second voltage amplitude; the third voltage amplitude is higher than the fourth voltage amplitude; the operating region includes a plurality of operating sub-regions; the sleep region includes a plurality of sleep sub-regions; the operating sub-regions and the sleep sub-regions are alternately arranged; a first ratio between a first duration of the operating region and a second duration of the second stage is less than a first predetermined value; a second ratio between the third duration of the sleep region and the second duration of the second stage is greater than a second predetermined value; 3. The cholesteric liquid crystal display device according to claim 2.
4. a first substrate on which a plurality of first electrodes extending in a first direction are formed; a second substrate on which a plurality of second 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; a drive circuitry configured to apply a plurality of alternating current (AC) voltage pulses to pixel circuits at intersections between the first electrodes and the second electrodes; a liquid crystal display panel including: a pulse width modulation (PWM) scanning procedure of the pixel circuits of the activated first electrodes, comprising a first stage and a second stage; the first stage is configured to manipulate the grayscale values of the pixel circuits of the activated first electrodes that are written in the second stage; Cholesteric liquid crystal display.
5. the first stage includes an active region and a sleep region; the AC voltage pulses in the operating region and the sleep region of the first stage have a first voltage amplitude and a second voltage amplitude, respectively; the second-stage AC voltage pulse has a third voltage amplitude; the first voltage amplitude is higher than the second voltage amplitude; 5. The cholesteric liquid crystal display device according to claim 4.
6. the pulse width modulation scanning procedure further includes a third stage identical to the first stage; the third stage, the first stage, and the second stage are arranged in sequence; 6. The cholesteric liquid crystal display device according to claim 5.
7. The pulse width modulation scanning procedure further comprises a third stage, the third stage, the first stage, and the second stage are arranged in sequence; The frequency and voltage amplitude of the AC voltage pulse in the first stage are different from the frequency and voltage amplitude of the AC voltage pulse in the third stage.
6. The cholesteric liquid crystal display device according to claim 5.
8. the pulse width modulation scanning procedure further includes a third stage for manipulating the gray scale values of the pixel circuits of the activated first electrodes written in the second stage; The first stage, the second stage, and the third stage are arranged in order, the AC voltage pulse of the third stage has a fifth voltage amplitude; the fifth voltage amplitude is between the second voltage amplitude and the third voltage amplitude; 6. The cholesteric liquid crystal display device according to claim 5.
9. applying a dark-state AC voltage pulse and a bright-state AC voltage pulse to a second electrode of the activated first electrode during the first and second stages to obtain a first RV (reflectance vs. voltage) curve and a second RV curve, respectively; a voltage interval exists between the first RV curve and the second RV curve within a specific voltage range; the drive circuitry is further configured to adjust the voltage interval using a plurality of drive parameters in the first stage; the driving parameters include a duration of the AC voltage pulse, a temperature and a viscosity of the cholesteric liquid crystal molecules in the cholesteric liquid crystal layer, a driving capability, and a pitch of the cholesteric liquid crystal helical structure in the cholesteric liquid crystal layer; a first region of the dark-state AC voltage pulse over time is equal to or greater than a second region of the light-state AC voltage pulse over time in the sleep region within the first stage; a third area of the bright state AC voltage pulse over time is greater than a fourth area of the dark state AC voltage pulse over time within the second stage; 6. The cholesteric liquid crystal display device according to claim 5.
10. A method for driving a cholesteric liquid crystal display device, comprising: The cholesteric liquid crystal display device includes a display panel and a driving circuit unit, the display panel includes a plurality of scanning electrodes and a plurality of data electrodes; activating each scanning electrode in the display panel in sequence using the driving circuit unit; applying one or more first alternating current (AC) voltage pulses to the pixel circuits of the active scan electrodes during a first phase of a pulse width modulation (PWM) scanning sequence of the active scan electrodes using the drive circuitry; applying one or more second AC voltage pulses to the pixel circuits of the activating scan electrodes during a second phase of the pulse width modulation scanning procedure using the drive circuitry; a first voltage amplitude and a first frequency of the one or more first AC voltage pulses are different from a second voltage amplitude and a second frequency of the one or more second AC voltage pulses, respectively; The first stage is for accelerating the pulse width modulation scanning procedure of the second stage so as to write data to the pixel circuits of the activated scanning electrodes, or for manipulating the gray scale values of the pixel circuits written in the second stage. A method for driving a cholesteric liquid crystal display device.