A cholesteric liquid crystal display device and a production method, control method thereof

Abstract

The present application relates to the field of liquid crystal display, particularly relates to a cholesteric liquid crystal display device and its production method and control method, including oppositely arranged first substrate, second substrate and liquid crystal composite layer between the first substrate and the second substrate;The liquid crystal composite layer includes parent liquid crystal and a plurality of liquid crystal microcapsules dispersed in the parent liquid crystal, the inside of each liquid crystal microcapsule is encapsulated with single pitch cholesteric liquid crystal;The pitch of the cholesteric liquid crystal in the inside of different kinds of liquid crystal microcapsules is different;The capsule wall of the liquid crystal microcapsule is a light-transmitting insulating layer;The threshold voltage of the parent liquid crystal is less than the threshold voltage of the cholesteric liquid crystal in any kind of liquid crystal microcapsule.The present application widens the reflection band of cholesteric liquid crystal display device, improves the dynamic tuning range, reduces light loss, improves the display brightness and contrast of the device, improves the mechanical stability and temperature stability of the device, and has good process compatibility.

Description

Technical Field

[0001] This invention relates to the field of liquid crystal displays, and in particular to a cholesteric liquid crystal display device and its manufacturing and control methods. Background Technology

[0002] With the development of technology, the harm of traditional displays to human eyes is becoming increasingly undeniable. As a result, electronic paper is gaining popularity. Among electronic paper technologies, cholesteric liquid crystal electronic paper is attracting more and more attention due to its ultra-low power consumption. It consumes almost no power when displaying static images, and only needs energy when refreshing the screen. The images can be maintained for months or even years without power, and the display characteristics are not affected even when the power is off.

[0003] To broaden the reflectivity band of cholesteric liquid crystals, current technologies often employ multilayer cholesteric liquid crystal stacking or multi-domain structures. However, these two processes are highly complex and cannot achieve dynamic electronic tuning. Some methods achieve a certain broadband reflectivity by creating continuous pitch variations within a single layer through external fields or compositional gradients, but these suffer from poor stability, high control precision requirements, and low repeatability. Other methods utilize polymer dispersion / stabilization of cholesteric liquid crystals, but these typically result in severe scattering, leading to low reflectivity and reduced contrast; their response speed and stability also require improvement.

[0004] Therefore, how to broaden the reflection band of existing cholesteric liquid crystal display devices, improve the dynamic tuning range, and simplify the device structure while ensuring high operational stability and high reliability has become an urgent problem for those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide a cholesteric liquid crystal display device and its manufacturing and control methods, so as to solve the problem that in the prior art, the wide reflection band, wide dynamic tuning range, and simple structure of cholesteric liquid crystal display devices cannot be simultaneously achieved with high working stability and reliability.

[0006] To solve the above-mentioned technical problems, the present invention provides a cholesteric liquid crystal display device, comprising a first substrate and a second substrate disposed opposite to each other, and a liquid crystal composite layer located between the first substrate and the second substrate;

[0007] A first electrode layer is disposed on the surface of the first substrate opposite to the surface of the second substrate; a second electrode layer is disposed on the surface of the second substrate opposite to the surface of the first substrate;

[0008] The liquid crystal composite layer includes a parent liquid crystal and various liquid crystal microcapsules dispersed in the parent liquid crystal. Each type of liquid crystal microcapsule encapsulates a cholesteric phase liquid crystal with a single pitch. The pitch of the cholesteric phase liquid crystal inside different types of liquid crystal microcapsules is different. The capsule wall of the liquid crystal microcapsule is a light-transmitting insulating layer.

[0009] The threshold voltage of the parent liquid crystal is less than the threshold voltage of the cholesteric phase liquid crystal in any of the liquid crystal microcapsules.

[0010] Optionally, in the cholesteric liquid crystal display device, the first electrode layer and / or the second electrode layer are transparent conductive electrodes.

[0011] Optionally, in the cholesteric liquid crystal display device, the first electrode layer and / or the second electrode layer are at least one of indium tin oxide electrode, tin-doped zinc oxide electrode, gallium-doped zinc oxide electrode, and fluorine-doped tin oxide electrode.

[0012] Optionally, in the cholesteric liquid crystal display device, the first electrode layer and / or the second electrode layer are electrode layers composed of a plurality of pixel unit electrodes arranged in an array.

[0013] Optionally, in the cholesteric liquid crystal display device, a first alignment layer is provided on the surface of the first electrode layer;

[0014] And / or,

[0015] A second alignment layer is disposed on the surface of the second electrode layer.

[0016] Optionally, in the cholesteric liquid crystal display device, the surface where the first substrate is located is the display surface of the cholesteric liquid crystal display device;

[0017] A black light-absorbing layer is disposed on the surface of the second substrate away from the liquid crystal composite layer.

[0018] Optionally, in the cholesteric phase liquid crystal display device, the thickness of the capsule wall ranges from 50 nanometers to 500 nanometers, including endpoint values;

[0019] And / or,

[0020] The diameter of the liquid crystal microcapsules ranges from 1 micrometer to 10 micrometers, including the endpoint values.

[0021] A method for manufacturing a cholesteric liquid crystal display device, the method comprising:

[0022] Prepare various liquid crystal microcapsules as described above;

[0023] A composite slurry is obtained by dispersing various liquid crystal microcapsules in the parent liquid crystal;

[0024] The composite slurry is filled between the first substrate and the second substrate and then encapsulated to obtain the cholesteric liquid crystal display device.

[0025] A method for controlling a cholesteric liquid crystal display device, the method being used to control any of the cholesteric liquid crystal display devices described above, comprising:

[0026] Receive the target display effect;

[0027] Determine the target voltage based on the target display effect;

[0028] The target voltage is applied between the first electrode layer and the second electrode layer, causing the parent liquid crystal with a threshold voltage lower than the target voltage and the cholesteric liquid crystal inside the liquid crystal microcapsule to convert to the FC state, so that the cholesteric liquid crystal display device presents the target display effect.

[0029] Optionally, in the control method of the cholesteric liquid crystal display device, determining the target voltage based on the target display effect includes:

[0030] The target voltage is determined based on the target display effect; the target voltage is less than the threshold voltage of the cholesteric phase liquid crystal in any type of liquid crystal microcapsule;

[0031] Accordingly, applying the target voltage between the first electrode layer and the second electrode layer includes:

[0032] The target voltage is applied between the first electrode layer and the second electrode layer to change the refractive index contrast between the parent liquid crystal and the liquid crystal microcapsule, thereby enabling the cholesteric liquid crystal display device to present the target display effect.

[0033] The cholesteric liquid crystal display device provided by the present invention includes a first substrate and a second substrate disposed opposite to each other, and a liquid crystal composite layer located between the first substrate and the second substrate; a first electrode layer is disposed on the surface of the first substrate and the second substrate opposite to each other; a second electrode layer is disposed on the surface of the second substrate and the first substrate opposite to each other; the liquid crystal composite layer includes a parent liquid crystal and a variety of liquid crystal microcapsules dispersed in the parent liquid crystal, each of the liquid crystal microcapsules encapsulating cholesteric liquid crystal with a single pitch; the pitch of the cholesteric liquid crystal inside the different types of liquid crystal microcapsules is different; the capsule wall of the liquid crystal microcapsule is a light-transmitting insulating layer; the threshold voltage of the parent liquid crystal is less than the threshold voltage of the cholesteric liquid crystal in any of the liquid crystal microcapsules.

[0034] This invention allows for continuous and reversible adjustment of the reflection spectrum of the entire device by adjusting the voltage between the first and second substrates. The spectrum can be adjusted from broadband reflection covering the entire visible light range to narrowband reflection at specific wavelengths, significantly broadening the reflection band of the cholesteric liquid crystal display device and improving the dynamic tuning range. Furthermore, the single-layer structure composed of two substrates, compared to the multilayer structures in existing technologies, reduces light loss and significantly improves the display brightness and contrast. Simultaneously, the liquid crystal microcapsules unitize and isolate the cholesteric liquid crystal, improving the device's mechanical and temperature stability, resulting in good process compatibility and suitability for large-area, flexible production. This invention also provides a method for producing and controlling a cholesteric liquid crystal display device with the aforementioned beneficial effects. Attached Figure Description

[0035] To more clearly illustrate the technical solutions of the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 A schematic diagram of a specific embodiment of the cholesteric liquid crystal display device provided by the present invention;

[0037] Figure 2 A schematic flowchart illustrating a specific embodiment of the production method of the cholesteric liquid crystal display device provided by the present invention;

[0038] Figure 3 A flowchart illustrating a specific embodiment of the control method for the cholesteric liquid crystal display device provided by the present invention;

[0039] Figure 4 A schematic diagram of the reflective broadband of a specific embodiment of the cholesteric liquid crystal display device provided by the present invention;

[0040] Figures 5 to 9 This is a schematic diagram of the structure of a specific embodiment of the cholesteric liquid crystal display device provided by the present invention under different external voltages.

[0041] Figure label:

[0042] 10-First substrate; 11-First electrode layer; 20-Second substrate; 21-Second electrode layer; 30-Liquid crystal composite layer; 31-Main liquid crystal; 32-Liquid crystal microcapsule with pitch P1; 33-Liquid crystal microcapsule with pitch P2; 34-Liquid crystal microcapsule with pitch P3; 35-Capsule wall; 40-Black light-absorbing layer. Detailed Implementation

[0043] To enable those skilled in the art to better understand the present invention, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] The core of this invention is to provide a cholesteric liquid crystal display device, the structural schematic diagram of one specific embodiment of which is shown below. Figure 1 As shown, this is referred to as Specific Embodiment 1, which includes a first substrate 10 and a second substrate 20 disposed opposite to each other, and a liquid crystal composite layer 30 located between the first substrate 10 and the second substrate 20.

[0045] A first electrode layer 11 is disposed on the surface of the first substrate 10 opposite to the surface of the second substrate 20; a second electrode layer 21 is disposed on the surface of the second substrate 20 opposite to the surface of the first substrate 10.

[0046] The liquid crystal composite layer 30 includes a parent liquid crystal 31 and various liquid crystal microcapsules dispersed in the parent liquid crystal 31. Each type of liquid crystal microcapsule encapsulates a cholesteric phase liquid crystal with a single pitch. The pitch of the cholesteric phase liquid crystal inside different types of liquid crystal microcapsules is different. The capsule wall 35 of the liquid crystal microcapsule is a light-transmitting insulating layer.

[0047] The threshold voltage of the parent liquid crystal 31 is less than the threshold voltage of the cholesteric phase liquid crystal in any of the liquid crystal microcapsules.

[0048] The different pitches of the cholesteric liquid crystal mean different threshold voltages, and also different reflection wavelengths.

[0049] The liquid crystal microcapsules encapsulate cholesteric liquid crystal within micron-sized capsules, endowing the liquid crystal material with excellent mechanical stability, flexibility, compatibility, and encapsulation protection. The capsule wall 35 is at least one of gelatin, gum arabic, polymethyl methacrylate, polyurea, and polyvinyl alcohol. These materials ensure good light transmittance, insulation, and mechanical strength; other transparent polymer materials can also be used.

[0050] Of course, the pitch values ​​of the cholesteric liquid crystals in different types of liquid crystal microcapsules in the cholesteric liquid crystal display device can exhibit discrete or quasi-continuous distributions to meet different display requirements, and can be selected according to actual conditions.

[0051] Specifically, the pitch of the various liquid crystal microcapsules covers a reflection wavelength range of 400 nm to 700 nm, including endpoint values ​​such as 400.0 nm, 521.4 nm, or 700.0 nm; the parent liquid crystal 31 is a nematic liquid crystal or a cholesteric liquid crystal with a pitch greater than 800 nm. The above range represents the optimal parameter range after extensive theoretical calculations and practical verification.

[0052] In a preferred embodiment, the parent liquid crystal 31 is doped with a chiral agent to shorten the pitch of the parent liquid crystal 31. The higher the concentration of the chiral agent, the shorter the pitch, which can further adjust the threshold voltage of the parent liquid crystal 31 and provide a larger dynamic tuning range for the cholesteric liquid crystal display device.

[0053] The first electrode layer 11 and / or the second electrode layer 21 are transparent conductive electrodes, further improving light transmittance. More specifically, the transparent conductive electrode is at least one of indium tin oxide (ITO), tin-doped zinc oxide (ZNO), gallium-doped ZNO, or fluorine-doped tin oxide. Electrodes made of the above materials exhibit good light transmittance and excellent conductivity, as well as good chemical stability and adhesion. Of course, other types of conductive materials can also be used to fabricate the first electrode layer 11 and / or the second electrode layer 21, such as using metal thin films and / or metal meshes. The metal can be gold, silver, copper, etc., to fabricate ultrathin films (thickness range of 5~20 nm). This invention does not limit the specific metal used.

[0054] In one specific embodiment, the first electrode layer 11 and / or the second electrode layer 21 are electrode layers composed of multiple arrayed pixel unit electrodes.

[0055] In other words, in this specific embodiment, the first electrode layer 11 and / or the second electrode layer 21 are pixel array layers formed by patterning. Each pixel unit electrode can be independently controlled to realize active matrix or passive matrix driving of the cholesteric liquid crystal display device, thereby increasing the complexity of the display pattern and expanding the applicability of the present invention. Of course, the first electrode layer 11 and / or the second electrode layer 21 can also be surface electrodes, which can be adjusted according to the actual situation.

[0056] Furthermore, a first alignment layer is disposed on the surface of the first electrode layer 11;

[0057] And / or,

[0058] A second alignment layer is provided on the surface of the second electrode layer 21.

[0059] In this preferred embodiment, an alignment layer is provided on at least one electrode layer facing the surface of the parent liquid crystal 31. The first alignment layer and the second alignment layer are only different in their positions. The alignment layer can initially align the parent liquid crystal 31, improve the alignment of the liquid crystal, and thus improve the working stability and reliability of the cholesteric liquid crystal display device.

[0060] In another preferred embodiment, the surface of the first substrate 10 is the display surface of the cholesteric liquid crystal display device;

[0061] A black light-absorbing layer 40 is disposed on the surface of the second substrate 20 away from the liquid crystal composite layer 30.

[0062] In other words, in this preferred embodiment, a black light-absorbing layer 40 is provided on the backlight surface of the cholesteric liquid crystal display device. When all the liquid crystals in the cholesteric liquid crystal display device are in a light-transmitting state, black is displayed, which can further reduce the FC state reflectivity and improve the contrast.

[0063] As one specific embodiment, the thickness of the capsule wall 35 ranges from 50 nanometers to 500 nanometers, including endpoint values ​​such as at least one of 50.0 nanometers, 288.4 nanometers, or 500.0 nanometers. Within the above range, the capsule wall 35 can maintain good light transmittance while providing sufficient insulation and mechanical strength. Of course, other thicknesses can also be selected according to actual conditions, which will not be elaborated here.

[0064] In addition, the diameter of the liquid crystal microcapsule is in the range of 1 micrometer to 10 micrometers, including the endpoint value, such as any one of 1.0 micrometer, 5.6 micrometer or 10.0 micrometer. Within the above diameter range, the liquid crystal microcapsule can ensure good optical uniformity and driving efficiency. Of course, other diameters can also be selected according to actual conditions, which will not be elaborated here.

[0065] The cholesteric liquid crystal display device provided by the present invention includes a first substrate 10 and a second substrate 20 disposed opposite to each other, and a liquid crystal composite layer 30 located between the first substrate 10 and the second substrate 20; a first electrode layer 11 is disposed on the surface opposite to the first substrate 10 and the second substrate 20; a second electrode layer 21 is disposed on the surface opposite to the second substrate 20 and the first substrate 10; the liquid crystal composite layer 30 includes a parent liquid crystal 31 and a variety of liquid crystal microcapsules dispersed in the parent liquid crystal 31, each of the liquid crystal microcapsules encapsulating a cholesteric liquid crystal with a single pitch; the pitch of the cholesteric liquid crystal inside the different types of liquid crystal microcapsules is different; the capsule wall 35 of the liquid crystal microcapsules is a light-transmitting insulating layer; the threshold voltage of the parent liquid crystal 31 is less than the threshold voltage of the cholesteric liquid crystal in any of the liquid crystal microcapsules. This invention allows for continuous and reversible adjustment of the reflection spectrum of the entire device by adjusting the voltage between the first substrate 10 and the second substrate 20. The spectrum can be adjusted from broadband reflection covering the entire visible light range to narrowband reflection at specific wavelengths, significantly broadening the reflection band of the cholesteric liquid crystal display device and improving the dynamic tuning range. Furthermore, the single-layer structure composed of two substrates, compared to the multi-layer structures in existing technologies, reduces light loss and significantly improves the display brightness and contrast. Simultaneously, the liquid crystal microcapsules unitize and isolate the cholesteric liquid crystal, improving the device's mechanical and temperature stability, resulting in good process compatibility and suitability for large-area, flexible production. The described cholesteric liquid crystal display device can be applied in reflective displays, electronic paper, smart dimming windows, or optical anti-counterfeiting fields.

[0066] The present invention also provides a method for producing a cholesteric liquid crystal display device, the process flow diagram of one specific embodiment of which is shown below. Figure 2 As shown, referred to as Specific Embodiment Two, the method for producing the cholesteric liquid crystal display device is used to produce any of the above-described cholesteric liquid crystal display devices, comprising:

[0067] S101: Prepare various liquid crystal microcapsules.

[0068] S102: Disperse the various liquid crystal microcapsules in the parent liquid crystal 31 to obtain a composite slurry.

[0069] S103: The composite slurry is filled between the first substrate 10 and the second substrate 20 and then encapsulated to obtain the cholesteric liquid crystal display device.

[0070] The manufacturing method of the cholesteric liquid crystal display device in this specific embodiment corresponds to the cholesteric liquid crystal display device described above. Therefore, the technical details of each structure in this specific embodiment can be found in the previous text and will not be repeated here.

[0071] Preferably, the method for preparing liquid crystal microcapsules is at least one of the following: emulsion method, complex coagulation method, interfacial polymerization method, or microfluidic method.

[0072] The present invention provides a method for producing a cholesteric liquid crystal display device. This method is used to produce any of the cholesteric liquid crystal display devices described above. The method involves preparing various liquid crystal microcapsules; dispersing these microcapsules in a parent liquid crystal 31 to obtain a composite slurry; filling the composite slurry between a first substrate 10 and a second substrate 20 and encapsulating it to obtain the cholesteric liquid crystal display device. By adjusting the voltage between the first substrate 10 and the second substrate 20, the present invention can continuously and reversibly adjust the reflection spectrum of the entire device, from broadband reflection covering the entire visible light range to narrowband reflection at specific wavelengths. This significantly broadens the reflection band of the cholesteric liquid crystal display device and improves the dynamic tuning range. Furthermore, the single-layer structure composed of two substrates, compared to the multilayer structures in the prior art, reduces light loss and significantly improves the display brightness and contrast. Simultaneously, the liquid crystal microcapsules unitize and isolate the cholesteric liquid crystal, improving the mechanical and temperature stability of the device. It also offers good process compatibility and is suitable for large-area, flexible production.

[0073] The following is a specific embodiment of a production method for the cholesteric liquid crystal display device in actual production, referred to as Embodiment 1, including:

[0074] The first step involved preparing liquid crystal microcapsules with various pitches: Nematic liquid crystal E7 was selected as the matrix, and a chiral agent with a high HTP value, S1011, was chosen. The concentration of the chiral agent corresponding to the required central reflection wavelength was calculated using the Bragg formula. Accurate weighing was performed to prepare three cholesteric liquid crystal mixtures with different central reflection wavelengths. For example, blue corresponded to a central reflection wavelength of approximately 450 nm, green to approximately 550 nm, and red to approximately 650 nm. Each mixture was heated to an isotropic state and thoroughly stirred to ensure complete dissolution of the chiral agent, forming a uniform and transparent cholesteric liquid crystal. Gelatin and gum arabic were selected as the microcapsule wall materials, and blue, green, and red microcapsules were prepared using a complex coagulation method. The microcapsules were repeatedly washed with deionized water until the supernatant was neutral, yielding a wet powder of the microcapsules. The three colored wet powders were then dispersed separately with a small amount of ethanol and passed through a sieve to remove excessively large agglomerates. Blue, green, and red microcapsules were mixed in an equal mass ratio (1:1:1) to obtain a mixed microcapsule powder.

[0075] The second step is to prepare the liquid crystal microcapsule composite layer: Nematic liquid crystal E7, which has good compatibility with the core material, is selected as the parent liquid crystal 31. The above-mentioned mixed microcapsule powder is mixed with E7 in a specific ratio. A small amount of surfactant, such as Span 80, is added, and the mixture is gently stirred in a low-temperature water bath until a uniform and stable paste-like composite slurry is formed, with no visible phase separation.

[0076] The third step is the fabrication of the display device: Two glass substrates with ITO transparent electrodes are cleaned, spin-coated with polyimide (PI) alignment liquid, and cured at 180°C and subjected to friction treatment to form an alignment layer. Spacers with a diameter of 10 μm are uniformly distributed on the PI layer of the lower substrate. The prepared liquid crystal microcapsule composite slurry is dropped onto the center of the lower substrate. Then, the upper substrate is aligned and covered with the ITO side facing inwards, and slight pressure is applied to spread the slurry throughout the entire display area. The edges are sealed with UV-curable adhesive. The assembled liquid crystal cell is placed on a 60°C hot stage for 2 hours to allow for more uniform distribution of the microcapsules within the cell and to eliminate alignment defects caused by flow. The final result is a display device with a cell thickness of approximately 10 ± 0.5 μm.

[0077] Another example, embodiment 2, includes:

[0078] The first step involved preparing liquid crystal microcapsules with a quasi-continuous pitch distribution. Nematic liquid crystal 5CB was selected as the matrix, and chiral agent CB15 was added in a gradient concentration manner. Specifically, five equal portions of 5CB were prepared, and five different concentrations of CB15 were added to each. The theoretical reflection peak coverage of the 300nm–700nm range was calculated. These five portions of cholesteric liquid crystal were mixed with the oil-soluble monomer toluene-2,4-diisocyanate (TDI), with the TDI addition amount being 10% of the total oil phase weight, forming the oil phase of the microcapsules. Polyvinyl alcohol (PVA), the wall material of the microcapsules, and sodium dodecyl sulfate (SDS), the surfactant, were dissolved in deionized water as the continuous phase. Under high-speed homogenization, the mixed oil phase was slowly poured into the aqueous phase, emulsifying to form a fine, uniform O / W emulsion. The emulsion was transferred to a three-necked flask and slowly stirred in a 40°C water bath. Then, an aqueous solution of the water-soluble monomer ethylenediamine was added dropwise. Ethylenediamine diffuses to the oil-water interface and undergoes a condensation reaction with TDI to form a polyurea wall material. After the reaction, the mixture is repeatedly centrifuged and washed with deionized water to obtain a wet powder of microcapsules with a smooth surface and uniform particle size distribution. This "one-pot method" directly yields a mixture of microcapsules with a quasi-continuous pitch distribution, eliminating the need for subsequent physical mixing.

[0079] The second step involves preparing a photoresponsive matrix liquid crystal 31 composite slurry: Nematic liquid crystal SLC1717 is selected as the matrix substrate. To enhance the tuning effect, a small amount of azobenzene photosensitive dye (such as DR1) is added. This dye undergoes cis-trans isomerization under ultraviolet / visible light irradiation, causing a local change in the refractive index of the matrix. A chiral agent CB15 is added to form a cholesteric phase with a pitch of approximately 2 μm (the reflection peak is in the infrared and does not affect visible light), providing an initial helical structure and enhancing the modulation capability of the microcapsule reflected light. The above-mentioned microcapsule wet powder is directly mixed with the prepared photoresponsive matrix liquid crystal 31 in a specific ratio. An appropriate amount of dispersant, such as BYK-361N, is added, and the mixture is ultrasonically treated at room temperature to form a highly dispersed composite slurry with good flowability.

[0080] The third step is the assembly of the flexible device: A thin film with ITO / PET flexible electrodes is selected, and a layer of silica nanoparticles is self-assembled on its surface using the Langmuir-Blodgett method to form a scattering enhancement layer with a micro-rough structure to improve the diffuse reflection effect of reflected light. The composite paste is then screen-printed onto a designated patterned area (e.g., a 2cm × 2cm square) on the lower flexible substrate. The upper flexible substrate (without the scattering layer) is then aligned and covered with the electrode face down. A UV-curable epoxy resin is used to seal the edges, and UV curing is applied to form a flexible thin-film device with a thickness of approximately 25μm.

[0081] The present invention also provides a control method for a cholesteric liquid crystal display device, the flowchart of one specific embodiment of which is shown below. Figure 3 As shown, referred to as Specific Embodiment Three, the control method for the cholesteric liquid crystal display device is used to control any of the above-described cholesteric liquid crystal display devices, including:

[0082] S201: Receive the target display effect.

[0083] S202: Determine the target voltage based on the target display effect.

[0084] S203: The target voltage is applied between the first electrode layer 11 and the second electrode layer 21, so that the threshold voltage of the parent liquid crystal 31 and the cholesteric liquid crystal in the liquid crystal microcapsules below the target voltage is converted to the FC state, so that the cholesteric liquid crystal display device presents the target display effect.

[0085] The control method of the cholesteric liquid crystal display device in this specific embodiment still corresponds to the cholesteric liquid crystal display device described above. Therefore, the technical details of each structure in this specific embodiment can be referred to the previous text and will not be repeated here.

[0086] The following is a specific embodiment to help understand the control method of the cholesteric liquid crystal display device in this specific embodiment. Assume that the cholesteric liquid crystal display device has three corresponding liquid crystal microcapsules with different pitches, P1, P2, and P3, respectively, and the pitch of the parent liquid crystal 31 is P0. The corresponding reflection broadband schematic diagram is shown below. Figure 4 As shown, λ0 corresponds to the center reflection wavelength of the parent liquid crystal 31 with pitch P0, λ1 corresponds to the center reflection wavelength of the cholesteric liquid crystal with pitch P1 inside the microcapsule, λ2 corresponds to the center reflection wavelength of the cholesteric liquid crystal with pitch P2 inside the microcapsule, and λ3 corresponds to the center reflection wavelength of the cholesteric liquid crystal with pitch P3 inside the microcapsule.

[0087] When no voltage is applied between the first electrode layer 11 and the second electrode layer 21, i.e., V0=0V, both the parent liquid crystal 31 in the cholesteric liquid crystal display device and the liquid crystal in the microcapsule are in the P state, with a continuous pitch distribution, which can exhibit wide-band reflection, such as... Figure 5 As shown.

[0088] Increase the voltage between the two electrode layers to the threshold voltage V of the parent liquid crystal 31. th-P0 and above, i.e., V1≥V th-P0 At this time, the parent liquid crystal 31 changes to the FC state, while the cholesteric liquid crystal inside the microcapsule remains in the P state. This results in a mixture of colors from various microcapsules, such as... Figure 6 As shown; continue increasing the voltage to the threshold voltage V of the cholesteric liquid crystal (the corresponding liquid crystal microcapsule is represented by 32 in the figure) with a pitch of P1. th-P1 and above, i.e., V2≥V th-P1 At this time, the parent liquid crystal 31 and the cholesteric liquid crystal with pitch P1 are both in the FC state, while the cholesteric liquid crystals in the other two microcapsules are still in the P state. The resulting color is a mixture of the two microcapsules in the P state, such as... Figure 7 As shown; continue increasing the voltage to the threshold voltage V of the cholesteric liquid crystal (the corresponding liquid crystal microcapsule is represented by 33 in the figure) with a pitch of P2. th-P2 and above, i.e., V3≥V th-P2 At this time, the parent liquid crystal 31 and the cholesteric liquid crystals with pitches P1 and P2 are simultaneously in the FC state, leaving only the cholesteric liquid crystal with pitch P3 (the corresponding liquid crystal microcapsule is represented by 34 in the figure) still in the P state. The color at this time reflects the wavelength of this P-state microcapsule, such as... Figure 8 As shown; increase the voltage to a sufficiently large value, i.e., V. H The parent liquid crystal 31 and the cholesteric liquid crystal in the microcapsule undergo unwinding, exhibiting the H state. By slowly reducing the voltage, the parent liquid crystal 31 and the cholesteric liquid crystal in the microcapsule can be restored to the initial P state.

[0089] As one specific implementation method, determining the target voltage based on the target display effect includes:

[0090] The target voltage is determined based on the target display effect; the target voltage is less than the threshold voltage of the cholesteric phase liquid crystal in any type of liquid crystal microcapsule;

[0091] Accordingly, applying the target voltage between the first electrode layer 11 and the second electrode layer 21 includes:

[0092] The target voltage is applied between the first electrode layer 11 and the second electrode layer 21, causing a change in the refractive index contrast between the parent liquid crystal 31 and the liquid crystal microcapsule, so that the cholesteric liquid crystal display device presents the target display effect.

[0093] When there is zero electric field between the first electrode layer 11 and the second electrode layer 21, the device is in the off state, and the parent liquid crystal 31 is in a disordered or planar textured state. Since the pitch of the cholesteric liquid crystal within the liquid crystal microcapsules is fixed and varies, each microcapsule independently reflects its corresponding Bragg wavelength. The superposition of reflected light from a large number of randomly distributed microcapsules macroscopically exhibits broadband reflection (e.g., white or light-colored), with the reflection bandwidth determined by the pitch range of the contained microcapsules.

[0094] Once an electric field is applied between the first electrode layer 11 and the second electrode layer 21, the device switches to the on state. When the voltage applied between the two electrode layers exceeds the threshold of the parent liquid crystal 31, the molecules of the parent liquid crystal 31 begin to rearrange along the direction of the electric field (i.e., the dielectric anisotropy of the liquid crystal is utilized). Due to the insulating isolation of the capsule wall 35 of the liquid crystal microcapsule, the cholesteric liquid crystal structure inside the capsule is basically unaffected by the direct electric field.

[0095] As the applied voltage increases further, the refractive index of the parent liquid crystal 31 changes. According to the effective medium theory, light passing through the composite layer experiences the average refractive index environment of the parent liquid crystal 31 and the liquid crystal microcapsules as a whole. Changes in the refractive index of the external parent liquid crystal 31 affect the behavior of light at the microcapsule interface and equivalently modulate the apparent pitch or refractive index contrast of the cholesteric phase structure of each microcapsule, thus causing a shift or weakening of its reflection peak. Because microcapsules with different pitches have different sensitivities to changes in the parent environment, a continuous and reversible electrical tuning of the overall shape (i.e., bandwidth) and center wavelength of the macroscopic reflection spectrum is ultimately achieved. For example, the reflection of broadband white light can be gradually narrowed and blue-shifted to a specific monochromatic reflection.

[0096] This invention is the first to propose and realize the organic combination of a composite structure of "multi-pitch liquid crystal microcapsules + tunable parent liquid crystal 31" and an "indirect environmental electrical tuning" mechanism. By encapsulating and insulating cholesteric liquid crystals with different fixed pitches, and then using a single, uniform electric field to control the refractive index of the outer parent liquid crystal 31 encapsulating them, the overall reflection spectrum of all microcapsules is indirectly and synergistically changed. This concept fundamentally changes the traditional paradigm of cholesteric liquid crystals, which is "single pitch corresponds to single color" and "direct electric field action," and realizes continuous and reversible electrical tuning of reflection bandwidth and color within a single-layer device.

[0097] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section.

[0098] It should be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0099] The cholesteric liquid crystal display device and its manufacturing and control methods provided by the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the present invention.

Claims

1. A cholesteric liquid crystal display device, characterized in that, It includes a first substrate and a second substrate disposed opposite to each other, and a liquid crystal composite layer located between the first substrate and the second substrate; A first electrode layer is disposed on the surface of the first substrate opposite to the surface of the second substrate; a second electrode layer is disposed on the surface of the second substrate opposite to the surface of the first substrate; The liquid crystal composite layer includes a parent liquid crystal and various liquid crystal microcapsules dispersed in the parent liquid crystal. Each type of liquid crystal microcapsule encapsulates a cholesteric phase liquid crystal with a single pitch. The pitch of the cholesteric phase liquid crystal inside different types of liquid crystal microcapsules is different. The capsule wall of the liquid crystal microcapsule is a light-transmitting insulating layer. The threshold voltage of the parent liquid crystal is less than the threshold voltage of the cholesteric phase liquid crystal in any of the liquid crystal microcapsules.

2. The cholesteric liquid crystal display device as described in claim 1, characterized in that, The first electrode layer and / or the second electrode layer are transparent conductive electrodes.

3. The cholesteric liquid crystal display device as described in claim 2, characterized in that, The first electrode layer and / or the second electrode layer are at least one of indium tin oxide electrode, tin-doped zinc oxide electrode, gallium-doped zinc oxide electrode, and fluorine-doped tin oxide electrode.

4. The cholesteric liquid crystal display device as described in claim 1, characterized in that, The first electrode layer and / or the second electrode layer are electrode layers composed of multiple pixel unit electrodes arranged in an array.

5. The cholesteric liquid crystal display device as described in claim 1, characterized in that, A first alignment layer is disposed on the surface of the first electrode layer; And / or, A second alignment layer is disposed on the surface of the second electrode layer.

6. The cholesteric liquid crystal display device as described in claim 1, characterized in that, The surface of the first substrate is the display surface of the cholesteric liquid crystal display device; A black light-absorbing layer is disposed on the surface of the second substrate away from the liquid crystal composite layer.

7. The cholesteric liquid crystal display device as described in claim 1, characterized in that, The thickness of the capsule wall ranges from 50 nanometers to 500 nanometers, including endpoint values; And / or, The diameter of the liquid crystal microcapsules ranges from 1 micrometer to 10 micrometers, including the endpoint values.

8. A method for producing a cholesteric liquid crystal display device, characterized in that, The method for producing the cholesteric liquid crystal display device is used to produce the cholesteric liquid crystal display device as described in any one of claims 1 to 7, comprising: Prepare various liquid crystal microcapsules as described above; A composite slurry is obtained by dispersing various liquid crystal microcapsules in the parent liquid crystal; The composite slurry is filled between the first substrate and the second substrate and then encapsulated to obtain the cholesteric liquid crystal display device.

9. A control method for a cholesteric liquid crystal display device, characterized in that, The control method for the cholesteric liquid crystal display device is used to control the cholesteric liquid crystal display device as described in any one of claims 1 to 7, comprising: Receive the target display effect; Determine the target voltage based on the target display effect; The target voltage is applied between the first electrode layer and the second electrode layer, causing the parent liquid crystal with a threshold voltage lower than the target voltage and the cholesteric liquid crystal inside the liquid crystal microcapsule to convert to the FC state, so that the cholesteric liquid crystal display device presents the target display effect.

10. The control method for the cholesteric liquid crystal display device as described in claim 9, characterized in that, Determining the target voltage based on the target display effect includes: The target voltage is determined based on the target display effect; the target voltage is less than the threshold voltage of the cholesteric phase liquid crystal in any type of liquid crystal microcapsule; Accordingly, applying the target voltage between the first electrode layer and the second electrode layer includes: The target voltage is applied between the first electrode layer and the second electrode layer to change the refractive index contrast between the parent liquid crystal and the liquid crystal microcapsule, thereby enabling the cholesteric liquid crystal display device to present the target display effect.

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