CN209928179U

CN209928179U - Multistable liquid crystal display device

Info

Publication number: CN209928179U
Application number: CN201920793012.2U
Authority: CN
Inventors: 王叶通; 李常良
Original assignee: Shenzhen Photosynthetic Display Technology Co Ltd
Current assignee: Shenzhen Photosynthetic Display Technology Co Ltd
Priority date: 2019-05-29
Filing date: 2019-05-29
Publication date: 2020-01-10
Anticipated expiration: 2029-05-29

Abstract

The utility model belongs to the technical field of show, a multistable liquid crystal display device is provided, include: a first substrate, the inner side of which is attached with a first electrode layer, the first electrode layer comprises a plurality of first electrode patterns; a second substrate, a second electrode layer attached to the inner side of the second substrate, the second electrode layer including a plurality of second electrode patterns; a liquid crystal layer sealed between the first substrate and the second substrate; the opposite parts of the first electrode patterns and the second electrode patterns form a plurality of pixel units, each pixel unit comprises a plurality of primary color pixels, and liquid crystal parts corresponding to different primary color pixels in the liquid crystal layer have different screw pitches, so that the liquid crystal part of each primary color pixel can reflect light with corresponding wavelength. The utility model discloses can all realize full-color demonstration to each pixel unit, under the prerequisite that keeps multistable liquid crystal display device low-power consumption, expand multistable liquid crystal display device's colour scope, contrast and luminance have also obtained the improvement.

Description

Multistable liquid crystal display device

Technical Field

The utility model belongs to the technical field of the display, especially, relate to a multistable liquid crystal display device.

Background

Liquid crystal displays are currently spread in various fields of life and industry, and among them, there are liquid crystal displays that need to be driven in real time and display in cooperation with a backlight, and multistable liquid crystal displays that display depending on ambient light.

The multistable liquid crystal display has the advantages that the display content does not depend on the self-lighting of the device, but depends on ambient light for displaying, the basic display principle is that the liquid crystal corresponding to a pixel needing to be displayed is in one state (the state can be extinction), the liquid crystal corresponding to a pixel needing not to be displayed is in the other state (the state reflects light), and the two states are stable states, namely the state can be kept for more than a few months after power failure. The power consumption of the device is mainly used for refreshing action of changing the display state of the device, and no energy is consumed after the device is refreshed, so the power consumption of the display technology is particularly low.

However, the color that such a multistable liquid crystal display device can display is relatively single, and generally only single color display is performed in each stable state, for example, only black/yellow can be displayed, one stable state is black and the other stable state is yellow, and black and yellow cannot be displayed simultaneously, or only blue/white and the like can be displayed, one stable state is blue, the other stable state is white, and blue and white cannot be displayed simultaneously, so that the display effect is limited.

SUMMERY OF THE UTILITY MODEL

The utility model discloses the problem that will solve can show multiple colour simultaneously for how to realize the multistable liquid crystal display that the color is abundant, promotes the display effect.

In order to solve the above technical problem, the utility model provides a multistable liquid crystal display device, include:

a first substrate, a first electrode layer attached to the inner side of the first substrate, the first electrode layer including a plurality of first electrode patterns;

a second substrate, a second electrode layer attached to the inner side of the second substrate, the second electrode layer comprising a plurality of second electrode patterns;

a liquid crystal layer sealed between the first substrate and the second substrate;

wherein, the opposite parts of the first electrode patterns and the second electrode patterns form a plurality of pixel units, and each pixel unit comprises a plurality of primary color pixels;

the liquid crystal portions of the liquid crystal layer corresponding to different primary color pixels have different pitches, so that the liquid crystal portion of each primary color pixel can reflect light of a corresponding wavelength.

Further, each primary color pixel has a plurality of corresponding electrodes in the first electrode pattern or the second electrode pattern, and the control of the corresponding primary color pixel can be realized by controlling each electrode.

Further, a first alignment layer is arranged between the liquid crystal layer and the first electrode layer, and a second alignment layer is arranged between the liquid crystal layer and the second electrode layer.

Further, an anti-reflection layer, an anti-glare layer or a scratch-proof protective layer is attached to the outer side of the first substrate.

Further, the multistable liquid crystal display device further comprises a reflecting layer, and the reflecting layer is located on the outer side of the second substrate or between the liquid crystal layer and the second electrode layer.

Further, the liquid crystal layer comprises a polymer network structure and liquid crystals positioned in the polymer network structure to form a liquid crystal domain structure.

Further, the liquid crystal is cholesteric liquid crystal, and the cholesteric liquid crystal comprises two chiral agents, wherein the HTP value of one chiral agent is increased along with the increase of the temperature, and the HTP value of the other chiral agent is decreased along with the increase of the temperature.

The utility model discloses a set up multiple primary color pixel with every pixel element to the liquid crystal part of each primary color pixel can reflect the light that corresponds the wavelength, consequently can all realize full-color demonstration to each pixel element, under the prerequisite that keeps multistable liquid crystal display device low-power consumption, the colour scope with multistable liquid crystal display device has been expanded, thereby make multistable liquid crystal display device's color become abundant, contrast and luminance have also obtained the improvement, the all-round display effect that has promoted.

Drawings

Fig. 1 is a cross-sectional view of a multistable liquid crystal display device according to a first embodiment of the present invention;

fig. 2 is a design diagram of a first electrode pattern according to a first embodiment of the present invention;

fig. 3 is a design diagram of a second electrode pattern provided in the first embodiment of the present invention;

fig. 4 is a schematic diagram of a pixel unit according to a first embodiment of the present invention;

fig. 5 is a design diagram of a pixel unit with multiple primary colors according to a first embodiment of the present invention;

fig. 6 is a schematic diagram of the pitch of the primary color pixels according to the first embodiment of the present invention;

fig. 7 is a schematic diagram of the pitch of another primary color pixel provided in the first embodiment of the present invention;

fig. 8 is a flowchart of a method for manufacturing a multistable liquid crystal display device according to a second embodiment of the present invention;

fig. 9 is an outline view of a liquid crystal empty cell according to a second embodiment of the present invention;

fig. 10 is a schematic diagram of forming a pitch of a red pixel according to a second embodiment of the present invention;

fig. 11 is a schematic diagram of forming green pixel pitches according to the second embodiment of the present invention;

fig. 12 is a schematic diagram of forming a pitch of blue pixels according to a second embodiment of the present invention;

fig. 13A is a planar structure diagram of cholesteric liquid crystal according to a third embodiment of the present invention;

fig. 13B is a focal conic texture of cholesteric liquid crystal according to a third embodiment of the present invention;

fig. 13C is a schematic view of a vertical alignment state of cholesteric liquid crystal according to a third embodiment of the present invention;

fig. 14 is a flowchart of a driving method according to a third embodiment of the present invention;

fig. 15 is a driving waveform diagram provided by a third embodiment of the present invention;

fig. 16 is a detailed flowchart of a driving method according to a third embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The utility model discloses a multistable liquid crystal display device is provided to first embodiment, and figure 1 is this multistable display device's cross-sectional view, including first base plate 101, second base plate 107 and the sealed liquid crystal layer 104 between first base plate 101 and second base plate 107, specifically can adopt the epoxy to glue sealedly. The first electrode layer 102 is attached to the inner side of the first substrate 101, the second electrode layer 106 is attached to the inner side of the second substrate 107, the first alignment layer 103 may be disposed between the liquid crystal layer 104 and the first electrode layer 102, the second alignment layer 105 may be disposed between the liquid crystal layer 104 and the second electrode layer 106, and grooves are rubbed on both the first alignment layer 103 and the second alignment layer 105 to anchor liquid crystal molecules.

The first substrate 101 and the second substrate 107 may be made of flexible materials or rigid materials, such as glass, and the first electrode layer 102 and the second electrode layer 106 are conductive layers, for example, when the first substrate 101 is made of glass, the first electrode layer 102 may be an ITO (indium tin oxide) layer attached to the glass. Further, some optical functional layers, such as an anti-reflection layer and an anti-glare layer, may be disposed on the outer side of the first substrate 101, and a scratch-proof protective layer may be disposed to protect the first substrate 101. The multistable liquid crystal display device may further comprise a reflective layer 108, and the reflective layer 108 may be disposed outside the second substrate 107 or between the liquid crystal layer 104 and the second electrode layer 106.

In addition, a silicon dioxide layer may be provided between the first electrode layer 102 and the first alignment layer 103, and may be used as a functional material for improving an optical effect or a functional material for improving electrical characteristics of a device, so as to prevent a short circuit between the first electrode layer 102 and the second electrode layer 106.

In addition, some Spacer particles (spacers) may be sprayed between the first alignment layer 103 and the second alignment layer 105 to support the liquid crystal layer 104 to have a uniform thickness.

For example, fig. 2 shows the shape of the first electrode pattern by taking a longitudinal strip-shaped electrode pattern PV as an example, each strip-shaped electrode pattern PV is sequentially arranged along the horizontal direction, fig. 3 shows the shape of the second electrode pattern by taking a transverse strip-shaped electrode pattern PL as an example, each strip-shaped electrode pattern PL is sequentially arranged along the vertical direction, as shown in fig. 4, the facing portions of the electrode pattern PV and the electrode pattern PL constitute a plurality of pixel units P, and image display can be realized by controlling the on-off state of each pixel unit P.

It should be understood that the first electrode pattern may also adopt the transverse long stripe electrode pattern PL shown in fig. 3, the second electrode pattern may also adopt the longitudinal long stripe electrode pattern PV shown in fig. 2, and although the electrode patterns are shown in fig. 2 and 3 by way of example of long stripes, the electrode patterns may be designed into other various shapes according to specific requirements in practical implementation.

As shown in fig. 2, the electrode pattern PV includes therein a plurality of sub-electrode patterns R, G, B as patterns for forming pixels of three primary colors of R (red) G (green) B (blue), respectively, facing portions of the sub-electrode pattern R and the electrode pattern PL constitute a red pixel PR, facing portions of the sub-electrode pattern G and the electrode pattern PL constitute a green pixel PG, and facing portions of the sub-electrode pattern B and the electrode pattern PL constitute a blue pixel PB, that is, as shown in fig. 5, each pixel unit P includes pixels of a plurality of primary colors, such as a red pixel PR, a green pixel PG, a blue pixel PB, and the like. It should be noted that fig. 2, fig. 4, and fig. 5 only illustrate the types of the primary color pixels included in the pixel unit P by using three primary colors of red, green, and blue as examples, and the specific implementation time-base pixels may also be other types, such as two primary colors or four primary colors.

The liquid crystal layer 104 contains a polymer network structure, and since the polymer network structure has anchoring and isolating effects on liquid crystal molecules, each primary color pixel corresponds to a certain pitch, so that liquid crystal parts corresponding to different primary color pixels can be controlled to reflect light with different wavelengths. As shown in fig. 6, the first electrode layer 102 has three primary color pixels, i.e., a red pixel PR, a green pixel PG, and a blue pixel PB, the pitch of the liquid crystal portion corresponding to the red pixel PR is S1, the pitch of the liquid crystal portion corresponding to the green pixel PG is S2, and the pitch of the liquid crystal portion corresponding to the blue pixel PG is S3, wherein the red pixel PR can reflect red light, the green pixel PG can reflect green light, and the blue pixel PG can reflect blue light.

Moreover, each pixel unit P includes a plurality of primary color pixels, so that different color display can be realized by the color mixing principle of colorimetry, for example, when the red pixel PR is turned on, and the green pixel PG and the blue pixel PB are turned off, the pixel unit P can display red, and similarly, two colors of green and blue can be respectively displayed; similarly, when the green pixel PG and the blue pixel PB are turned on and the red pixel PR is turned off simultaneously, the pixel unit P may display a cyan color, and when the red pixel PR and the blue pixel PB are turned on and the green pixel PG is turned off simultaneously, the pixel unit P may display a magenta color; when the red, green, and blue pixels PR, PG, and PB are simultaneously turned on, white may be displayed, and when the red, green, and blue pixels PR, PG, and PB are simultaneously turned off, black may be displayed. It can be seen that the pixel cell shown in fig. 6 can realize eight colors of red, green, blue, yellow, cyan, magenta, white, and black display, which is more power-saving than the conventional LCD/OLED display and also richer in color than the conventional bistable display.

Further, the electrodes corresponding to the primary color pixels may be further subdivided to improve a higher-level color display, as shown in fig. 7, each of the primary color pixels in the first electrode layer 102 has a plurality of electrodes, for example, a red pixel PR has four electrodes PR1, PR2, PR3, and PR4, a green pixel PG has four electrodes PG1, PG2, PG3, and PG4, a blue pixel PG has four electrodes PB1, PB2, PB3, and PB4, and controlling each of the electrodes can achieve control over the corresponding primary color pixel, for example, corresponding to the red pixel PR, a part or all of the four electrodes PR1, PR2, PR3, and PR4 can be selectively driven, and the same applies to the green pixel PG and the blue pixel PB. After the electrodes corresponding to the primary color pixels are divided as shown in fig. 7, each primary color pixel may have 4 gray levels, so that a total of 4 × 4 — 64 levels of color display can be realized by the three RGB primary colors. If the electrodes corresponding to the pixels of the primary colors are further divided into 8 gray scales, so that the three primary colors of RGB can achieve color display of 8 × 8 — 512 levels in total, and which electrodes of each primary color pixel are driven can be selected to achieve different display effects, for example, when two electrodes of the red pixel PR need to be selected and driven, the electrodes may be electrodes PR1 and PR2, or may be electrodes PR1 and PR4, the former displays a low pixel graininess, and the latter displays a heavy pixel graininess.

As described above, the liquid crystal layer 104 contains a polymer network structure, which can be formed by doping a suitable polymer into the liquid crystal and matching with different ultraviolet light irradiation processes to form corresponding polymer networks on the pixels of the primary colors, and the liquid crystal is located in the polymer network structure to form a liquid crystal domain structure. Specifically, the liquid crystal layer 104 contains liquid crystal and polymer capable of undergoing polymerization under the action of ultraviolet light, wherein the liquid crystal is compatible with the polymer, and the mass ratio of the liquid crystal to the polymer is (100-70): 0-30; the polymer includes 93 parts by mass of an oligomer, 5 parts by mass of a diluent, and 2 parts by mass of a photoinitiator.

For liquid crystal, according to the physical principle of liquid crystal, the arrangement of liquid crystal molecules is influenced by boundary conditions, liquid crystal phase and external field conditions, and the arrangement distribution of the liquid crystal molecules is also an important factor for determining the form of the liquid crystal display. The selection process of the liquid crystal is described below by taking cholesteric liquid crystal as an example, and the liquid crystal is generally obtained by adding a chiral agent to nematic liquid crystal.

First, selection of nematic liquid crystal: in this example, it is preferable to use liquid crystals having a high Δ n, a high Δ ∈, a low melting point, and a low viscosity, and since it is difficult for the electro-optical characteristics of the liquid crystal monomer to satisfy all the requirements of the liquid crystal for display, the liquid crystals to be actually used are mixed with liquid crystal compounds of the same series or similar series, and each electro-optical parameter is made to approach the compounding ratio target by an addition method. The liquid crystal selected in this example is prepared by mixing a polyaromatic liquid crystal, a tolan liquid crystal, a polyacetylene liquid crystal and the like as main components with 5CB, 7CB, PTP-5O2 and the like, for example, 22.14 parts of polyaromatic liquid crystal, 17.93 parts of tolan liquid crystal, 40.55 parts of polyacetylene liquid crystal, 3.00 parts of 5CB, 9.31 parts of 7CB and 7.07 parts of PTP-5O2 are fully mixed for standby, and the mixed liquid crystal is called nematic liquid crystal mixture 1. The molecular formula of the liquid crystal is as follows:

polyaromatic liquid crystal

Diphenyl acetylene liquid crystal

Polyacetylene liquid crystal

5CB

7CB

PTP-5O2

Secondly, the chiral agent is selected: the chiral agent used in this embodiment may preferably be a temperature-insensitive chiral agent for reducing the influence of temperature drift of the device and optimizing the display effect of the device at different temperatures, or two chiral agents with opposite temperature characteristics may be used simultaneously, wherein the HTP (twisting power) value of one chiral agent increases with increasing temperature and the HTP value of the other chiral agent decreases with increasing temperature, and the mixed use can eliminate the influence of the chiral agent on the temperature. The chiral agents selected in the embodiment are R1011 and CB15, the optical rotation direction of the R1011 chiral agent is dextrorotation, the HTP value is 28.2 mu m < -1 >, and the HTP value is increased along with the temperature rise; the optical rotation direction of CB15 is left-handed, the HTP value is 7.9 μm-1, and the HTP decreases with the temperature.

According to Bragg reflection, the central wavelength λ 0 ═ n × p of the device reflection, where n is the average refractive index of the liquid crystal mixture and p is the pitch of the liquid crystal mixture. The relationship between the pitch p of the liquid crystal mixture and the chiral agent is as follows:

p 1/(HTP Xc), Xc is the molar concentration of the chiral agent

The pitch of the cholesteric liquid crystal can be controlled to be 300-850 nm, for example 700nm, in the long wavelength stage by adjusting the amount of the chiral agent in the configuration stage.

Finally, mixing of nematic liquid crystals with a chiral agent:in this example, 5 parts of R1011, 13 parts of CB15, and 82 parts of nematic liquid crystal mixture 1 were mixed thoroughly and homogeneously to obtain a cholesteric liquid crystal mixture.

For polymers, the oligomers in this embodiment have an important effect on the final optical effect of the device, where the oligomers can rapidly form a main body of a polymer network under ultraviolet light, the main body has a strong anchoring effect on liquid crystal molecules, the forming speed of the main body, the concentration in the liquid crystal mixture, and the like all affect the pitch of the liquid crystal, and thus affect the reflection wavelength and color effect of the pixel.

Preferred oligomers should have liquid crystal properties and good compatibility with liquid crystals, such as diacrylate monomers or diepoxide monomers, 1, 2-ethylene glycol 2-methyl-2-acrylate, 2-hydroxypropyl methacrylate, and methyl hexyl carbinol, and 1-hydroxycyclohexyl phenyl ketone as the photoinitiator, and the formula is as follows:

2-methyl-2-propenoic acid 1, 2-ethanediol ester

2-hydroxypropyl methacrylate

Methyl hexyl carbinol

1-hydroxycyclohexyl phenyl methanones

For example, the oligomer may include 65 parts by mass of 1, 2-ethylene glycol 2-methyl-2-acrylate and 28 parts by mass of 2-hydroxypropyl methacrylate; the diluent is methyl hexyl methanol; the photoinitiator is 1-hydroxycyclohexyl phenyl ketone.

It can be seen that, the utility model discloses the first embodiment is through setting up multiple primary color pixel with every pixel element to the liquid crystal part of each primary color pixel can reflect the light that corresponds the wavelength, consequently can all realize full-color to each pixel element and show, under the prerequisite that keeps multistable liquid crystal display device low-power consumption, the colour scope with multistable liquid crystal display device has been expanded, thereby make multistable liquid crystal display device's color become abundant, contrast and luminance have also obtained the improvement, the all-round display effect that has promoted.

The second embodiment of the present invention further provides a method for manufacturing a multistable liquid crystal display device, as shown in fig. 8, including the following steps:

in step S801, a liquid crystal empty cell is fabricated.

The liquid crystal cell has the structural design described in the first embodiment, for example, including a first substrate with a first electrode layer attached to the inner side thereof, and a second substrate with a second electrode layer attached to the inner side thereof, wherein the first electrode layer includes a plurality of first electrode patterns, and the second electrode layer includes a plurality of second electrode patterns; the opposite parts of the first electrode patterns and the second electrode patterns form a plurality of pixel units, and each pixel unit comprises a plurality of primary color pixels.

The liquid crystal empty box has the shape shown in fig. 9, and a liquid filling port is generally reserved in the liquid crystal empty box to facilitate subsequent liquid filling.

And step S802, filling liquid. And injecting liquid crystal containing a polymer which can be subjected to polymerization reaction under the action of ultraviolet light into the liquid crystal empty box and sealing to obtain the liquid crystal box.

As described in the first embodiment, the liquid crystal layer includes liquid crystal and polymer capable of undergoing polymerization under the action of ultraviolet light, and the liquid crystal is compatible with the polymer; the mass ratio of the liquid crystal to the polymer is (100-70) to (0-30); the polymer includes 93 parts by mass of an oligomer, 5 parts by mass of a diluent, and 2 parts by mass of a photoinitiator. The liquid filling process is as follows:

65 parts of 2-methyl-2-acrylic acid-1, 2-glycol ester, 28 parts of 2-hydroxypropyl methacrylate, 5 parts of methyl hexyl methanol and 2 parts of 1-hydroxycyclohexyl phenyl ketone are fully and uniformly mixed for later use, and the mixed solution is called a polymer mixture.

92 parts of cholesteric liquid crystal mixture (such as the cholesteric liquid crystal mixture in the first embodiment) and 8 parts of polymer mixture are well mixed uniformly for standby application, the mixed solution is called cholesteric liquid crystal polymer mixture, the mixture is poured into a liquid crystal empty box through a liquid filling opening, and then the liquid filling opening is sealed.

In this embodiment, the UV light is an important process control condition that can determine the final fabrication and performance of the device, and therefore, it is necessary to perform the polymer formulation step under a yellow environment.

In step S803, the pitch of each primary color pixel is formed. For each primary color pixel, covering the liquid crystal box by using a mask corresponding to the primary color pixel, and then irradiating ultraviolet light by using the illumination parameters corresponding to the primary color pixel until the liquid crystal parts corresponding to all the primary color pixels are irradiated, so that the liquid crystal parts corresponding to different primary color pixels in the liquid crystal layer have different pitches.

The main principle is to use different photolithography boards to mask and perform curing reaction by ultraviolet illumination. The degree of polymer reaction will vary with different lighting conditions (different wavelengths, different light intensities, different reaction times). For example:

formation of red pixel pitch: selecting ultraviolet light with the wavelength of 340nm for illumination, wherein the illumination intensity is 3mW/cm2, as shown in figure 10, using a red pixel mask for masking and illuminating for 5 minutes, reacting the cholesteric liquid crystal polymer mixture under the ultraviolet light, gradually separating the polymers to form a polymer network, changing the polymer network formed by main chain components into individual liquid crystal domains, taking the upper and lower layers of the liquid crystal domains and the liquid crystal box as boundary conditions of liquid crystal molecules, having strong anchoring effect on the liquid crystal molecules, and combining with a chiral agent to form a spiral microstructure with the screw pitch of 680 nm.

Formation of green pixel pitch: as shown in FIG. 11, after the pitch of the red pixels is formed, the green pixel mask is replaced, and the mask is irradiated for 10 minutes by using ultraviolet light with a wavelength of 340nm and an illumination intensity of 5mW/cm 2. Due to the increased intensity of the light, the polymer reacts more fully than in the red pixels, resulting in an increased proportion of the chiral agent in the polymer. According to the proportion relation between the liquid crystal pitch and the chiral agent in the polymer: p is 1/(HTP Xc), and the pitch of the liquid crystal in the green pixel after the polymer reaction is 550 nm.

Formation of blue pixel pitch: as shown in FIG. 12, after the pitch of the green pixel is formed, the blue pixel mask is replaced, and ultraviolet light with a wavelength of 340nm and an illumination intensity of 7mW/cm2 is adopted for 15 minutes. As the illumination intensity is continuously increased, the polymer reaction is more sufficient than in the red pixel and the green pixel, so that the component proportion of the chiral agent in the polymer is increased. According to the proportion relation between the liquid crystal pitch and the chiral agent in the polymer: p is 1/(HTP Xc), and the pitch of the liquid crystal in the blue pixel after the polymer reaction is 420 nm.

The third embodiment of the present invention provides a driving method of a multistable liquid crystal display device, which is suitable for the multistable liquid crystal display device provided by the first embodiment, or the multistable liquid crystal display device obtained by the manufacturing method provided by the second embodiment.

Cholesteric liquid crystals generally have two textures, a planar texture as shown in fig. 13A and a focal conic texture as shown in fig. 13B. In the planar texture, the cholesteric liquid crystal has a Bragg reflection characteristic, and can reflect light with a wavelength corresponding to the pitch of the cholesteric liquid crystal and consistent with the spiral direction, for example, the pitch of the cholesteric liquid crystal is 550nm, the spiral direction of the cholesteric liquid crystal is left-handed, so that under 380-780 nm natural light, left-handed circularly polarized light near a 550nm waveband can be reflected by the cholesteric liquid crystal, light of other wavebands and right-handed circularly polarized light near the 550nm waveband can pass through the liquid crystal layer, and the liquid crystal can show the color of the light corresponding to the waveband when viewed from one side of the liquid crystal layer. In the focal conic texture, the liquid crystal has no reflection effect on all bands of light, and all bands of light can be transmitted through the liquid crystal. If a reflecting layer is added on one side of the cholesteric liquid crystal device, different control display empty energy can be realized by controlling the switching of different texture states of cholesteric liquid crystal.

Whether the cholesteric liquid crystal is in a plane texture or a focal conic texture, the two states are stable in a zero field under certain conditions, and the cholesteric liquid crystal can be controlled to be converted between the plane texture shown in fig. 13A, the focal conic texture shown in fig. 13B and the vertical arrangement state shown in fig. 13C by applying different driving conditions.

Referring to fig. 14 and fig. 15 together, the driving method provided in this embodiment includes the following steps:

step S141, preparation stage: using a first high voltage V_hAll primary color pixels in all pixel cells in a preselected region of the multistable liquid crystal display device are driven so that all liquid crystal molecules assume a fully homeotropic state as shown in fig. 13C.

The preselected area may be the entire area of the multi-stable liquid crystal display device, or may be only a part of the area in which the display needs to be updated, and may be set as needed. For example, the multistable liquid crystal device is applied to a supermarket and used for displaying the price of a certain commodity, wherein the first area is used for displaying the commodity name of 'article a', the second area is used for displaying the price of 'a 1 yuan/Kg' of the commodity, if the price needs to be adjusted today, only the price information displayed in the second area can be updated and displayed to be 'a 2 yuan/Kg', and at the moment, the second area is the pre-selected area of the current driving.

Step S142, selecting stage: using a first selection voltage V_sDriving the target primary color pixels to keep the liquid crystal parts corresponding to the target primary color pixels in a vertical arrangement state; using a second selection voltage V_nsThe non-target primary color pixels are driven so that the liquid crystal portions corresponding to the non-target primary color pixels relax from the vertically aligned state to the planar state.

The picture currently displayed by the target primary color pixel position needs the opened primary color pixel, and the picture currently displayed by the non-target primary color pixel position does not need the opened primary color pixel.

Step S143, evolution stage: using evolution of voltage V_eSimultaneously driving the target primary color pixel and the non-target primary color pixel to keep the liquid crystal part corresponding to the target primary color pixel in a vertical arrangement state so as to ensure that the non-target primary color pixel corresponds to the liquid crystal partThe liquid crystal portion relaxes from the planar state to the focal conic state shown in fig. 13B.

Step S144, removing the evolution stage: using evolution voltage V_eRemoving the evolution voltage V after continuously driving the target primary color pixel and the non-target primary color pixel for a preset time length_eThe target primary color pixels are relaxed to a planar state with a pitch change and then to a more stable planar state to maintain the non-target primary color pixels in a focal conic state.

Wherein the first high voltage V_h>Evolution voltage V_e>A first selection voltage V_s>A second selection voltage V_ns. The detailed flow of the driving method is shown in fig. 16.

Further, as described in the first embodiment, each primary color pixel has a plurality of corresponding electrodes in the first electrode pattern or the second electrode pattern, and the control of the corresponding primary color pixel can be realized by controlling each of the electrodes, so as to realize different display effects. At this time, when the preparation stage of step S141, the selection stage of step S142, and the evolution stage of step S143 are performed, it is possible to further refine which electrodes of the primary color pixels are specifically driven.

The preparation stage of step S141 is specifically: and for all primary color pixels in all pixel units in a preselected area of the multistable liquid crystal display device, driving a preset electrode of each primary color pixel by using a first high voltage to enable all liquid crystal molecules to be in a completely vertical arrangement state.

For example, as shown in fig. 7, for the red pixel PR, which includes four electrodes PR1, PR2, PR3, and PR4, which may be selectively driven according to the desired display effect, for example, when two of the electrodes need to be selectively driven, the electrodes PR1 and PR2, or PR1 and PR4, the former may display a lower pixel graininess, and the latter may display a higher pixel graininess.

The selection stage of step S142 is specifically: driving a preset electrode of a target primary color pixel by using a first selection voltage so as to keep a liquid crystal part corresponding to the target primary color pixel in a vertical arrangement state; the preset electrodes of the non-target primary color pixels are driven by a second selection voltage to relax the liquid crystal portions corresponding to the non-target primary color pixels from a vertically aligned state to a planar state.

The step S143 includes: and simultaneously driving the preset electrodes of the target primary color pixels and the preset electrodes of the non-target primary color pixels by using the evolution voltage so as to continuously keep the liquid crystal parts corresponding to the target primary color pixels in a vertical arrangement state and relax the liquid crystal parts corresponding to the non-target primary color pixels from a planar state to a focal conic state.

The above description is only exemplary of the present invention and should not be taken as limiting the scope of the present invention, as any modifications, equivalents, improvements and the like made within the spirit and principles of the present invention are intended to be included within the scope of the present invention.

Claims

1. A multistable liquid crystal display device comprising:

2. A multistable liquid crystal display device as claimed in claim 1 wherein each primary colour pixel has a corresponding plurality of electrodes in the first or second electrode pattern, control of the associated primary colour pixel being effected by control of each of said electrodes.

3. The multistable liquid crystal display device of claim 1 wherein a first alignment layer is between the liquid crystal layer and the first electrode layer and a second alignment layer is between the liquid crystal layer and the second electrode layer.

4. A multistable liquid crystal display device according to claim 1 wherein an anti-reflection layer or anti-glare layer or anti-scratch protective layer is attached to the outside of the first substrate.

5. The multistable liquid crystal display device of claim 1 further comprising a reflective layer located outside the second substrate or between the liquid crystal layer and the second electrode layer.

6. A multistable liquid crystal display device as claimed in claim 1 wherein the liquid crystal layer comprises a polymer network structure and liquid crystals located in the polymer network structure to form a liquid crystal domain structure.

7. Multistable liquid crystal display device according to claim 1, characterized in that the liquid crystal is cholesteric liquid crystal comprising two chiral agents, one of which has an HTP increasing with increasing temperature and the other has an HTP decreasing with increasing temperature.