A circular polarizer based on perspective compensation and a display device

Abstract

The present invention discloses a circular polarizing plate and a display device based on viewing angle compensation, belonging to the field of display technology. The circular polarizing plate of the present invention includes a cholesteric liquid crystal layer, a retardation layer, a linear polarizing layer, and a viewing angle compensation layer; the display device includes a display substrate and the above-mentioned circular polarizing plate. The cholesteric liquid crystal layer is located between the display substrate and the retardation layer, the linear polarizing layer is located on the side of the retardation layer away from the cholesteric liquid crystal layer, the viewing angle compensation layer is located between the cholesteric liquid crystal layer and the display substrate, and the light band regulated by the cholesteric liquid crystal includes at least some wavelengths between 440 and 680 nm. The viewing angle compensation layer is used to convert part of the light with a small viewing angle (0-30°) emitted from the display substrate into light with a large viewing angle (31-80°) emission angle, compensating for the problem of low brightening efficiency of the cholesteric liquid crystal at a large viewing angle and improving the display effect of the display device.

Description

Technical Field

[0001] The present invention belongs to the field of display technology and relates to a circular polarizer and a display device based on viewing angle compensation. Background Art

[0002] A circular polarizer is composed of a linear polarizer and a quarter-wave plate. It converts natural light into linearly polarized light through the linear polarizer, and then generates a phase delay through the quarter-wave plate to form left-handed (right-handed) circularly polarized light. After being reflected by the reflection layer of the display substrate, it is converted into right-handed (left-handed) circularly polarized light. The linearly polarized light after passing through the quarter-wave plate again has a polarization direction perpendicular to the transmission axis of the linear polarizer and is absorbed by the linear polarizer, thereby achieving the effect of shielding the reflection of ambient light. However, the above circular polarizer will also cause about 50% of the light emitted from the display substrate to be absorbed by the linear polarizer, resulting in a decrease in light extraction efficiency.

[0003] To improve the light extraction efficiency, the prior art often introduces a cholesteric liquid crystal layer, which realizes brightness enhancement by selectively reflecting light of a specific wavelength. However, at a large viewing angle, the helical structure of the cholesteric liquid crystal is sensitive to the incident angle, resulting in a shift in the reflection wavelength and the emitted light being elliptically polarized, and the brightness enhancement efficiency decreases rapidly as the emission angle of the light increases. Therefore, there is an urgent need for a circular polarizer that can compensate for the low brightness enhancement efficiency of the cholesteric liquid crystal layer at a large viewing angle to improve the display effect. Summary of the Invention

[0004] In view of the above technical problems and deficiencies, the present invention provides a circular polarizer and a display device based on viewing angle compensation. The present invention adds a viewing angle compensation layer between the cholesteric liquid crystal layer and the display substrate, broadening the angle of the light emitted from the display substrate, redistributing the light energy originally concentrated in a small viewing angle range to a larger viewing angle range, thereby compensating for the brightness attenuation of the cholesteric liquid crystal layer at a large viewing angle and improving the display effect of the display device at a large viewing angle.

[0005] In a first aspect, the present invention provides a circular polarizer based on viewing angle compensation. The circular polarizer is placed on a display substrate and includes a viewing angle compensation layer, a cholesteric liquid crystal layer, a retardation layer, and a linear polarizing layer.

[0006] The cholesteric liquid crystal layer is located between the display substrate and the retardation layer, the linear polarizing layer is located on the side of the retardation layer away from the cholesteric liquid crystal layer, and the viewing angle compensation layer is located between the cholesteric liquid crystal layer and the display substrate.

[0007] Further, in the circular polarizer based on viewing angle compensation provided by the present invention, the viewing angle compensation layer is selected from any one of a microstructure viewing angle compensation layer, a non-liquid crystal polymerizable coating added with viewing angle compensation particles, a liquid crystal polymerizable coating added with viewing angle compensation particles, and a polymerizable liquid crystal coating.

[0008] Further, in the circular polarizing plate based on view angle compensation provided by the present invention, the surface roughness Ra of the microstructure view angle compensation layer is 10 nm to 2 μm.

[0009] Further, in the circular polarizing plate based on view angle compensation provided by the present invention, the view angle compensation particles in the non-liquid crystal polymerizable coating added with view angle compensation particles are inorganic substances with a diameter of 10 nm to 30 μm and / or organic substances with a diameter of 1 μm to 50 μm.

[0010] Further, in the circular polarizing plate based on view angle compensation provided by the present invention, the inorganic substances are selected from at least one of titanium dioxide, calcium carbonate, barium sulfate, and silicon dioxide;

[0011] The organic substances are selected from at least one of polymethyl methacrylate, polybutyl methacrylate, polystyrene, polymerizable liquid crystal monomers, and silicone resin.

[0012] Further, in the circular polarizing plate based on view angle compensation provided by the present invention, the non-liquid crystal polymerizable coating added with view angle compensation particles is prepared by mixing and curing the view angle compensation particles and the non-liquid crystal polymerizable substance, and the mass ratio of the view angle compensation particles to the organic colloid is 0.1 to 1.2:1; the non-liquid crystal polymerizable colloid is one or a mixture of methyl methacrylate, butyl methacrylate, and styrene;

[0013] Further, in the circular polarizing plate based on view angle compensation provided by the present invention, the polymerizable liquid crystal coating is a liquid crystal polymer layer with a chiral compound-containing focal conic texture.

[0014] Further, in the circular polarizing plate based on view angle compensation provided by the present invention, the liquid crystal polymerizable coating added with view angle compensation particles is prepared by mixing the view angle compensation particles and the liquid crystal mixture, coating the mixture on a substrate layer, and then curing;

[0015] The mass ratio of the view angle compensation particles to the liquid crystal mixture is 0.1 to 1.2:1;

[0016] By mass, the liquid crystal mixture includes: 100 to 980 parts of polymerizable liquid crystal monomers, 5 to 300 parts of chiral compounds, 1 to 50 parts of photoinitiators, and 5 to 800 parts of organic solvents.

[0017] The substrate layer is an organic film with a thickness of 5 to 300 μm.

[0018] Further, in the circular polarizing plate based on view angle compensation provided by the present invention, the polymerizable liquid crystal monomers are selected from one or more of nematic liquid crystals, discotic liquid crystals, and disc-shaped liquid crystals;

[0019] The polymerizable liquid crystal monomers contain n polymerizable groups, where n ≥ 1;

[0020] The polymerizable group is one of alkenyl, alkynyl, epoxy group, and mercapto group.

[0021] In a second aspect, the present invention provides a display device, which includes the above-mentioned circular polarizer and a display substrate. The display device can be an organic light-emitting diode (OLED) or a liquid crystal display (LCD).

[0022] Compared with the prior art, the technical solution provided by the present invention has at least the following beneficial effects or advantages:

[0023] (1) By introducing a viewing angle compensation layer between the cholesteric liquid crystal layer and the display substrate, the present invention expands the light emission angle and improves the display effect of the display device. Among them, a mixture of inorganic and organic particles with different particle sizes is used as the viewing angle compensation particles, which utilizes the synergistic effect of the flexibility of the organic matter and the rigidity of the inorganic matter, optimizes the particle dispersion, and makes the brightness reach 95 nit at a viewing angle of 80°, which is better than that of a pure inorganic coating, compensating for the problem of low brightness enhancement efficiency of the cholesteric liquid crystal layer at large viewing angles.

[0024] (2) When the viewing angle compensation layer of the viewing angle compensation particles is combined with the liquid crystal polymer focal conic texture layer, the brightness attenuation is the gentlest over the full viewing angle (0° to 80°), especially significant at large angles of 31° to 80°. The balance between the positive viewing angle efficiency and the large viewing angle performance is achieved. Through the double optimization of materials and structures, the present invention solves the problems of low light efficiency and serious color shift at large viewing angles in the prior art, providing a new path for high-performance display technology.

[0025] (3) By disposing the viewing angle compensation layer between the display substrate and the cholesteric liquid crystal layer, the brightness enhancement efficiency of the cholesteric liquid crystal layer can be further improved, and part of the lost light reflected by the cholesteric liquid crystal layer to the edge of the display device is scattered back to the display substrate, improving the light extraction efficiency. Description of the Drawings

[0026] Figure 1 It is a schematic diagram of the brightness enhancement principle of the cholesteric liquid crystal layer. Among them, L is left-handed circularly polarized light; R is right-handed circularly polarized light; S00 is the display substrate; S100 is the cholesteric liquid crystal layer.

[0027] Figure 2 It is a schematic diagram of the structure of a non-liquid crystal polymerizable coating with viewing angle compensation particles of different sizes added. Among them, D is the adhesive layer; D1 is the viewing angle compensation particle with a particle size greater than 5 μm; D2 is the viewing angle compensation particle with a particle size between 500 nm and 5 μm, and D3 is the viewing angle compensation particle with a particle size less than 500 nm.

[0028] Figure 3Schematic diagram of brightness enhancement of the low optical path caused by the cholesteric liquid crystal layer from a large viewing angle. Among them, L is left-handed circularly polarized light; L’ is the lost left-handed circularly polarized light; R is right-handed circularly polarized light; R’ is the lost right-handed circularly polarized light; S00 is the display substrate; S100 is the cholesteric liquid crystal layer.

[0029] Figure 4 Schematic diagram of the compensation of the light extraction efficiency at a large viewing angle by the non-liquid crystal polymer coating with viewing angle compensation particles. Among them, L is left-handed circularly polarized light; R is right-handed circularly polarized light; P is linearly polarized light; S00 is the display substrate; S400 is the viewing angle compensation layer; S100 is the cholesteric liquid crystal layer; S200 is the retardation layer; S300 is the linear polarizer layer.

[0030] Figure 5 Schematic diagram of the compensation of the light extraction efficiency at a large viewing angle by the microstructured viewing angle compensation layer. Among them, L is left-handed circularly polarized light; R is right-handed circularly polarized light; P is linearly polarized light; S00 is the display substrate; S400 is the viewing angle compensation layer; S100 is the cholesteric liquid crystal layer; S200 is the retardation layer; S300 is the linear polarizer layer. Detailed implementation manners

[0031] Next, the technical solutions of the present invention will be described in conjunction with embodiments. However, the present invention is not limited to the following embodiments. The experimental methods and detection methods described in each embodiment are all conventional methods unless otherwise specified; the reagents and materials described are all commercially available unless otherwise specified.

[0032] The present invention provides a circular polarizer, which includes: a cholesteric liquid crystal layer, a retardation layer, a linear polarizer layer, and a viewing angle compensation layer.

[0033] The present invention also provides a display device, which includes a display substrate and the above-mentioned circular polarizer. The cholesteric liquid crystal layer is located between the display substrate and the retardation layer, the linear polarizer layer is located on the side of the retardation layer away from the cholesteric liquid crystal layer, and the viewing angle compensation layer is located between the cholesteric liquid crystal layer and the display substrate.

[0034] 1. Viewing angle compensation layer:

[0035] The light emitted from the display substrate has a small divergence angle. When directly incident on the cholesteric liquid crystal layer, its inherent helical structure and selective reflection characteristics will cause significant attenuation of large-angle light. In this case, the present invention inserts a viewing angle compensation layer between the substrate and the liquid crystal layer to pre-expand the angle of the light emitted from the display substrate, redistribute the light energy originally concentrated in a small viewing angle range to a larger viewing angle range, thereby compensating for the light efficiency loss of the cholesteric liquid crystal layer at a large viewing angle and improving the display effect of the display device at a large viewing angle.

[0036] The viewing angle compensation layer in the present invention is selected from any one of a microstructured viewing angle compensation layer, a non-liquid crystal polymerizable coating added with viewing angle compensation particles, a liquid crystal polymerizable coating added with viewing angle compensation particles, and a polymerizable liquid crystal coating. The viewing angle compensation layer in the present invention can perform multiple diffuse reflections on the light emitted from the display substrate, redistribute part of the light originally concentrated in the viewing angle range of 0° to 30° to the range of 0° to 80°, and reduce the brightness attenuation at large viewing angles. At the same time, the viewing angle compensation layer can scatter part of the light reflected by the cholesteric liquid crystal layer to the edge of the display device back into the display device and reuse it, improving the light extraction efficiency of the display device.

[0037] The preparation methods of the above different types of viewing angle compensation layers are as follows:

[0038] (1) Microstructured viewing angle compensation layer

[0039] The microstructured viewing angle compensation layer forms roughness ranging from 10 nm to 2 μm on the surfaces of film layers such as PET (polyethylene terephthalate), COP (cycloolefin polymer), PC (polycarbonate), and PMMA (polymethyl methacrylate) through a nanoimprint process.

[0040] (2) Non-liquid crystal polymerizable coating added with viewing angle compensation particles

[0041] The non-liquid crystal polymerizable coating added with viewing angle compensation particles is formed by mixing viewing angle compensation particles and a non-liquid crystal polymerizable substance, and then coating the mixture on the surface of a substrate and curing it by heat curing or light curing. The core function of the viewing angle compensation particles is to adjust the phase and angle of light, so they must have specific optical anisotropy. Therefore, the viewing angle compensation particles are selected from any one of inorganic substances, organic substances, and inorganic-organic mixtures. Among them, the inorganic substances are one or more of titanium dioxide, calcium carbonate, barium sulfate, and silicon dioxide with diameters between 10 nm and 30 μm; the organic substances are one or more of polymethyl methacrylate, polybutyl methacrylate, polystyrene, and silicone resin with diameters between 1 μm and 50 μm; the non-liquid crystal polymerizable substance is one or more mixtures of methyl methacrylate, butyl methacrylate, and styrene. As Figure 2 shown, the viewing angle compensation particles in the viewing angle compensation layer preferably have a distribution combination of particles with different diameters.

[0042] (3) Liquid crystal polymerizable coating added with viewing angle compensation particles

[0043] The liquid crystal polymerizable coating added with viewing angle compensation particles is prepared by mixing viewing angle compensation particles and a liquid crystal mixture, coating the mixture on a substrate layer, and then curing it; the liquid crystal mixture is a liquid crystal polymer with a focal conic texture containing a chiral compound; the mass ratio of the viewing angle compensation particles to the liquid crystal mixture is 0.1 to 1.2:1;

[0044] By mass parts, the liquid crystal mixture includes: 100 - 980 parts of polymerizable liquid crystal monomers, 5 - 300 parts of chiral compounds, 1 - 50 parts of photoinitiators, and 5 - 800 parts of organic solvents.

[0045] The substrate layer is an organic film with a thickness of 5 - 300 μm.

[0046] The polymerizable liquid crystal monomers are selected from one or more of nematic liquid crystals, discotic liquid crystals, and disc-shaped liquid crystals; the polymerizable liquid crystal monomers contain n polymerizable groups, where n ≥ 1; the polymerizable group is one of alkenyl, alkynyl, epoxy group, and mercapto group.

[0047] (4)Polymerizable liquid crystal coating

[0048] The polymerizable liquid crystal coating is a liquid crystal polymer layer with a chiral compound-containing focal conic texture.

[0049] 2. Cholesteric liquid crystal layer:

[0050] (1)Principle of light wave regulation of cholesteric liquid crystal layer:

[0051] The light wave regulation band of the cholesteric liquid crystal layer includes at least some wavelengths between 440 - 680 nm. In the light wave regulation band of the cholesteric liquid crystal layer, it includes at least one of the bands of 440 - 480 nm, 500 - 580 nm, and 600 - 680 nm. For example, the cholesteric liquid crystal layer can regulate the 440 - 480 nm light wave band; the cholesteric liquid crystal layer can regulate the 440 - 480 nm and 500 - 580 nm light wave bands; the cholesteric liquid crystal layer can regulate the 440 - 480 nm, 500 - 580 nm, and 600 - 680 nm light wave bands.

[0052] The cholesteric liquid crystal layer can have a single pitch structure or multiple pitch structures. When there are multiple pitch structures in the cholesteric liquid crystal layer, cholesteric liquid crystal structures with different pitch sizes can be arranged in any order in the thickness direction. For example, there is one pitch in the thickness direction of the cholesteric liquid crystal layer, such as 291 nm (denoted as P1). Assuming the average refractive index of the cholesteric liquid crystal layer is 1.58, the cholesteric liquid crystal layer regulates the central wavelength to be 460 nm; there are two pitches in the thickness direction of the cholesteric liquid crystal layer, such as a cholesteric liquid crystal polymer layer with a pitch size of 291 nm and a pitch size of 335 nm (denoted as P2). Assuming the average refractive index of the cholesteric liquid crystal layer is 1.58, the cholesteric liquid crystal layer regulates two central wavelengths, which are 460 nm and 530 nm respectively; there are three pitches in the thickness direction of the cholesteric liquid crystal layer, such as a three-layer cholesteric liquid crystal polymer layer with a pitch size of 291 nm, a pitch size of 335 nm, and a pitch size of 392 nm (denoted as P3). Assuming the average refractive index of the cholesteric liquid crystal layer is 1.58, the cholesteric liquid crystal layer regulates three central wavelengths to be 460 nm, 530 nm, and 620 nm; the three-layer cholesteric liquid crystal polymer layers P1, P2, and P3 can be arranged in any order in the thickness direction, such as P1 P2 P3, P2 P3 P1, P3 P2 P1, P3P1 P2, P1 P3 P2, P2 P1 P3.

[0053] When there are multiple pitch structures in the cholesteric liquid crystal layer, there is a continuous gradual change in the pitch size in the thickness direction of the cholesteric liquid crystal polymer layer. For example, the pitch in the thickness direction of the cholesteric liquid crystal layer includes some or all of the pitch sizes between 291 nm and 392 nm.

[0054] The relationship between the light wavelength regulated by the cholesteric liquid crystal layer and the pitch is as follows:

[0055]

[0056] In the above formula, λ is the light wavelength regulated by the cholesteric liquid crystal layer, n is the average refractive index of the cholesteric liquid crystal layer, P is the pitch of the cholesteric liquid crystal layer, and θ is the angle between the incident light and the helical axis of the cholesteric liquid crystal layer.

[0057] Such as Figure 1As shown, when the incident angle is 0, the light-enhancing optical path of the cholesteric liquid crystal layer is as follows: The cholesteric liquid crystal layer converts the light emitted by the display substrate into approximately 50% left-handed polarized light and approximately 50% right-handed polarized light. When the optical rotation selectivity of the cholesteric liquid crystal layer allows the left-handed polarized light (right-handed polarized light) to pass through, this part is denoted as Y1, then the right-handed polarized light (left-handed polarized light) (denoted as Y2) is reflected back to the reflective layer of the display substrate. After being reflected again by the reflective layer, the polarization direction of the light changes, that is, the left-handed polarized light (right-handed polarized light) becomes right-handed polarized light (left-handed polarized light). The circularly polarized light with the changed polarization direction can pass through the cholesteric liquid crystal layer, and after passing through the phase difference layer, it is converted into linearly polarized light, and the linearly polarized light then passes through the linear polarizer layer to reach the surface of the display device. From the above optical path, it can be seen that the cholesteric liquid crystal layer can greatly improve the light extraction efficiency of the display device.

[0058] As Figure 3 shown, when the incident angle is not 0, the light-enhancing optical path of the cholesteric liquid crystal layer is as follows: During the process that the Y2 part is reflected back to the reflective layer of the display substrate by the cholesteric liquid crystal layer, part of the light will be reflected to the edge of the display device, resulting in partial light loss; or the Y2 part is reflected back to the reflective layer of the display substrate by the cholesteric liquid crystal layer, and after being reflected by the reflective layer, part of the light will be reflected to the edge of the display device, resulting in partial light loss. The larger the viewing angle, the lower the light-enhancing efficiency of the cholesteric liquid crystal layer, which in turn leads to poor display effects at large viewing angles.

[0059] As Figure 4 shown, by adding a viewing angle compensation layer between the cholesteric liquid crystal layer and the display substrate to convert part of the small viewing angle light emitted from the display substrate into large viewing angle light, the light extraction efficiency at large viewing angles is compensated. At the same time, part of the large angle light reflected back to the display substrate by the cholesteric liquid crystal layer, after passing through the viewing angle compensation layer, the optical path changes, from the edge of the display device to the inside of the display device, thereby reducing light loss and improving the light extraction efficiency.

[0060] (2) Preparation of the cholesteric liquid crystal layer:

[0061] First step, pre-treat the substrate layer to improve the adhesion of the cholesteric liquid crystal coating. The pre-treatment method can be corona or plasma pre-treatment. For example, corona-treat the substrate layer with a corona power of 100V * 2A and a corona speed of 2m / min. The substrate layer preferably considers organic film layers that are easy to wind, such as PMMA film, TAC (triacetyl cellulose) film, COP film, etc., without specific limitation. The thickness of the substrate layer is 5 - 300μm, and the preferred thickness is 5 - 100μm.

[0062] Step 2: Prepare a liquid crystal mixture for coating to prepare a cholesteric liquid crystal layer. Weigh the raw materials for preparing the liquid crystal mixture in proportion. By mass fraction, the liquid crystal mixture includes: 10 - 98% of polymerizable liquid crystal monomers, 0.5 - 30% of chiral compounds, 0.1 - 5% of photoinitiators, and 0.5 - 80% of organic solvents. In some applications, other functional additives such as surfactants and crosslinking agents can also be added as required. Heat the measured liquid crystal mixture to a temperature above the phase transition temperature of all polymerizable liquid crystal monomers, stir while heating until it is uniformly mixed, and then cool it to 10 - 50 °C for coating.

[0063] The polymerizable liquid crystal monomers are selected from one or more of nematic liquid crystals, discotic liquid crystals, and disc-shaped liquid crystals. The polymerizable liquid crystal monomers contain at least one polymerizable group, and preferably contain two or more polymerizable groups. The polymerizable group is one of alkenyl, alkynyl, epoxy group, and mercapto group.

[0064] For example, the polymerizable liquid crystal monomers containing two or more polymerizable groups include:

[0065] L1:

[0066] ;

[0067] L2:

[0068] ;

[0069] L3:

[0070] ;

[0071] L4:

[0072] ;

[0073] L5:

[0074] ;

[0075] L6:

[0076] ;

[0077] L7:

[0078] ;

[0079] L8:

[0080] 。

[0081] The chiral compound is selected from one or more of X1, X2, X3, X4, X5, X6, X7, X8, X9, X10, X11, X12, X13, X14, X15, X16, X17, X18, X19, X20, X21.

[0082] The structure of X1 is:

[0083] ;

[0084] The structure of X2 is:

[0085] ;

[0086] The structure of X3 is:

[0087] ;

[0088] The structure of X4 is:

[0089] ;

[0090] The structure of X5 is:

[0091] ;

[0092] The structure of X6 is:

[0093] ;

[0094] The structure of X7 is:

[0095] ;

[0096] The structure of X8 is:

[0097] ;

[0098] The structure of X9 is:

[0099] ;

[0100] The structure of X10 is:

[0101] ;

[0102] The structure of X11 is:

[0103] ;

[0104] The structure of X12 is:

[0105] ;

[0106] The structure of X13 is as follows:

[0107] ;

[0108] The structure of X14 is as follows:

[0109] ;

[0110] The structure of X15 is as follows:

[0111] ;

[0112] The structure of X16 is as follows:

[0113] ;

[0114] The structure of X17 is as follows:

[0115] ;

[0116] The structure of X18 is as follows:

[0117] ;

[0118] The structure of X19 is as follows:

[0119] ;

[0120] The structure of X20 is as follows:

[0121] ;

[0122] The structure of X21 is as follows:

[0123] .

[0124] The photoinitiator is selected from one or more of the following: benzoyl peroxide, azobisisobutyronitrile, benzoin ethers, benzophenones, acetophenones, benzoyl ketal, diaryliodonium salts, triarylsulfonium salts, diphenyliodonium tetrafluoroborate, diphenyliodonium hexafluorophosphate, diphenyliodonium arsenate, diphenyliodonium tetraborate, 4-methoxyphenyliodonium tetrafluoroborate, 4-methoxyphenyliodonium hexafluorophosphate, 4-methoxyphenyliodonium hexafluoroarsenate, 4-tert-butylphenyliodonium diphenyliodonium tetrafluoroborate, 4-tert-butylphenyliodonium diphenyliodonium hexafluorophosphate, 4-tert-butylphenyliodonium diphenyliodonium trifluoromethanesulfonate, triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroarsenate, triphenylsulfonium tetraborate, 4-methoxyphenyldiphenylsulfonium tetrahydroborate, 4-methoxyphenyldiphenylsulfonium tetrahydrophosphate, 4-methoxyphenyldiphenylsulfonium tetrahydroarsenate, 4-methoxyphenyldiphenylsulfonium trifluoromethanesulfonate, 4-methoxyphenyldiphenylsulfonium triphenylsulfonium tetraborate, 4-phenylphenylthiodiphenylsulfonium hexafluoroarsenate, benzoyl dimethyl ketal, and bis-phenylphosphine oxide.

[0125] The solvent is selected from one or more of the following: benzene, toluene, xylene, mesitylene, n-butylbenzene, diethylbenzene, tetralin, methoxybenzene, 1,2-dimethoxybenzene, cyclohexanone, ethyl acetate, methyl lactate, ethyl lactate, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, 2-pyrrolidone, chloroform, dichloromethane, carbon tetrachloride, dichloroethane, trichloroethylene, tetrachloroethylene, chlorobenzene, tert-butanol, diacetone alcohol, glycerol, glycerol monoacetate, triethylene glycol, ethyl cellosolve, butyl cellosolve, N-methyl-2-pyrrolidone, γ-butyrolactone, N,N-dimethylformamide, N,N-dimethylacetamide, diethylene glycol monomethyl ether acetate, methanol, ethanol, isopropanol, cyclohexanol, ethylene glycol, tetrahydrofuran, dichloromethane, chlorobenzene, 1,2-dichloroethane, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclobutanone, methyl acetate, ethyl acetate, ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol methyl ethyl ether, ethylene glycol dimethyl ether.

[0126] In the third step, the liquid crystal mixture obtained in the second step is coated on the pre-treated substrate layer with a coating thickness of 100 - 5000 nm, and the organic solvent is removed by heating at a heating temperature of 30 - 150 °C for a heating time of 5 - 1000 s. Then, it is cured by irradiation with an irradiation light wavelength of 300 - 400 nm and an irradiation dose of 1000 - 200000 J / m 2 . When the cholesteric liquid crystal layer is composed of multiple layers of liquid crystal layers with a single pitch structure, after coating and curing the first cholesteric liquid crystal coating, the remaining cholesteric liquid crystal mixtures with different pitch sizes are successively coated until all the liquid crystal mixtures are coated.

[0127] 3. Phase difference layer:

[0128] The phase difference layer is a stretched type phase difference layer or a coated type phase difference layer. The stretched type phase difference layer can be made of PC or PET materials, and the coated type phase difference layer can be a liquid crystal coated type phase difference layer.

[0129] The phase difference layer preferably has a material or structure with inverse wavelength dispersion performance. For example, it is prepared by compounding multiple layers of nematic liquid crystal polymer coatings. There is a certain angle between the optical axes of each nematic liquid crystal polymer layer, or the liquid crystal polymer coating is a phase difference layer prepared by adding a chiral compound, and the optical axis changes in the thickness direction, thereby achieving inverse wavelength dispersion. The coated type liquid crystal phase difference layer is, for example, the inverse wavelength dispersion phase difference layer prepared in CN117844494A.

[0130] 4. Linear polarizer layer:

[0131] The linear polarizer layer can be an iodine-based polarizer layer or a dye-based polarizer layer, without specific limitation. The iodine-based polarizer is, for example, the linear polarizer layer of the commercially available Shengbo Optoelectronics model SMV-TDA, and the dye-based polarizer is, for example, the linear polarizer layer prepared in CN117844494A.

[0132] The cholesteric liquid crystal layer, the phase difference layer, the linear polarizer layer and the viewing angle compensation layer can all be pasted together through an optical adhesive.

[0133] The light-emitting side of the circular polarizer of the present invention may further include other functional layers, such as an anti-fingerprint layer, an anti-scratch layer, etc. In some possible applications, the viewing angle compensation layer can be used as an optical adhesive layer.

[0134] Example 1

[0135] This example provides a non-liquid crystal polymerizable coating added with viewing angle compensation particles.

[0136] (1) Design of viewing angle compensation particles

[0137] The viewing angle compensation particles in this example are inorganic substances, that is, silica with different particle sizes is mixed, and the mass percentages of silica with each particle size are shown in Table 1:

[0138] Table 1 Mass percentages of each component in inorganic substances

[0139]

[0140] 2. Construction of composite colloid

[0141] Disperse the above-mentioned inorganic substances in a methyl methacrylate matrix (a non-liquid crystal polymerizable substance), and then add benzoyl peroxide (BPO) as a thermal initiator. After stirring and mixing evenly, a composite colloid is obtained. The mass percentages of the components in the composite colloid are shown in Table 2. Coat the composite colloid on the surface of a PET substrate, heat it to 80 °C, and keep it for 5 minutes to obtain a non-liquid crystal polymerizable substance coating added with viewing angle compensation particles.

[0142] Table 2 Mass percentages of the components in the composite colloid

[0143]

[0144] Example 2

[0145] This example is the same as Example 1, except that the composition of the viewing angle compensation particles is different. In this example, the viewing angle compensation particles are an inorganic-organic mixture, and the composition of the inorganic-organic mixture is shown in Table 3, and the composition of the composite colloid is shown in Table 4.

[0146] Table 3 Mass percentages of the components in the inorganic-organic mixture

[0147]

[0148] Table 4 Mass percentages of the components in the composite colloid

[0149]

[0150] Example 3

[0151] This example is the same as Example 1, except that the composition of the viewing angle compensation particles is different. In this example, the viewing angle compensation particles are inorganic substances, and the composition of the inorganic substances is shown in Table 5, and the composition of the composite colloid is shown in Table 6.

[0152] Table 5 Mass percentages of the components in the inorganic substances

[0153]

[0154] Table 6 Mass percentages of the components in the composite colloid

[0155]

[0156] Example 4

[0157] This example is the same as Example 1, except that the composition of the viewing angle compensation particles is different. In this example, the viewing angle compensation particles are organic substances, and the composition of the organic substances is shown in Table 7, and the composition of the composite colloid is shown in Table 8.

[0158] Table 7 Mass percentages of the components in the organic substances

[0159]

[0160] Table 8 Mass percentage of each component in the composite colloid

[0161]

[0162] Example 5

[0163] This example provides a microstructure perspective compensation layer.

[0164] In this example, a nanoimprint process is used to form a roughness with Ra of 0.5 μm on the surface of polyethylene terephthalate (PET). The nanoimprint machine uses a commercially available Stensborg type roll-to-roll type to form a microstructure with an average roughness of 0.5 μm on the PET surface. As shown in Figure 5 S400 in the appendix.

[0165] Example 6

[0166] This example provides a liquid crystal polymerizable coating added with perspective compensation particles.

[0167] The preparation method of the liquid crystal polymerizable coating added with perspective compensation particles is similar to the preparation method of the cholesteric liquid crystal layer. The difference is that before coating the liquid crystal mixture, the perspective compensation particles are mixed evenly with the liquid crystal mixture, and the resulting coating mixture is coated on the surface of the substrate and cured to obtain the coating. The liquid crystal mixture is a liquid crystal polymer with a chiral compound and a focal conic texture. The specific preparation method is as follows:

[0168] The preparation method of the perspective compensation particles in this example is the same as that in Example 1. On the basis of Example 1, the preparation method of the liquid crystal polymerizable coating added with perspective compensation particles is as follows:

[0169] One side of the substrate TAC (triacetyl cellulose) film is corona-treated with a corona power of 100 V * 2 A and a corona speed of 2 m / min. The polymerizable liquid crystal monomer, chiral compound, photoinitiator, and solvent are measured according to the proportional amounts to obtain a liquid crystal mixture. The mass percentages of the liquid crystal mixture are shown in Table 9. The measured liquid crystal mixture is heated to 180 °C and stirred while heating until the liquid crystal mixture is evenly mixed. After cooling to 50 °C, the perspective compensation particles are mixed with the liquid crystal mixture, and the mass ratio of the perspective compensation particles to the liquid crystal mixture is 0.3:1 to form a coating mixture for standby.

[0170] Table 9 Mass percentage of each component in the liquid crystal mixture

[0171]

[0172] The coating mixture is applied to the corona-treated substrate layer through a slot coating process. The coating thickness is 3 μm, heated to 80 °C and held for 1 min to remove the solvent. The temperature is reduced to 20 °C and then cured by ultraviolet light irradiation. The ultraviolet light wavelength is 365 nm and the irradiation dose is 5000 J / m 2 , to obtain a liquid crystal polymerizable coating added with viewing angle compensation particles.

[0173] Example 7

[0174] This example provides a polymerizable liquid crystal coating.

[0175] The polymerizable liquid crystal coating described in this example is a liquid crystal polymer layer with a chiral compound and a focal conic texture.

[0176] One side of the substrate TAC (triacetyl cellulose) film is corona-treated with a corona power of 100 V * 2 A and a corona speed of 2 m / min. The polymerizable liquid crystal monomer, chiral compound, photoinitiator, and solvent are measured in proportion to obtain a liquid crystal mixture. The mass percentages of the liquid crystal mixture are shown in Table 9. The measured liquid crystal mixture is heated to 180 °C and stirred while heating until the liquid crystal mixture is evenly mixed, and then cooled to 20 °C to form a coating mixture for standby.

[0177] The coating mixture is applied to the corona-treated substrate layer through a slot coating process. The coating thickness is 3 μm, heated to 80 °C and held for 1 min to remove the solvent. The temperature is reduced to 20 °C and then cured by ultraviolet light irradiation. The ultraviolet light wavelength is 365 nm and the irradiation dose is 5000 J / m 2 , to obtain a polymerizable liquid crystal coating.

[0178] Example 8

[0179] This example provides a method for preparing a cholesteric liquid crystal layer.

[0180] The cholesteric liquid crystal layer has a single pitch structure in the thickness direction, with a pitch of 291 nm, a regulated central wavelength of 460 nm, a regulated light band of 440 - 480 nm, and a cholesteric liquid crystal layer thickness of 3 μm.

[0181] The method for preparing the cholesteric liquid crystal layer includes:

[0182] One side of the TAC (triacetyl cellulose) film is corona-treated with a corona power of 100 V * 2 A and a corona speed of 2 m / min. The polymerizable liquid crystal monomer, chiral compound, photoinitiator, and solvent are measured in proportion to obtain a liquid crystal mixture. The mass percentages of the liquid crystal mixture are shown in Table 10. The measured liquid crystal mixture is heated to 180 °C and stirred while heating until the liquid crystal mixture is evenly mixed, and then cooled to 30 °C for standby.

[0183] Mass percentage of each component of liquid crystal mixture in Table 10

[0184]

[0185] The liquid crystal mixture is coated on the corona-treated substrate layer by a slit coating process. The coating thickness is 3 μm, heated to 80 °C and held for 1 min to remove the solvent. Then it is cured by ultraviolet light irradiation. The wavelength of the ultraviolet light is 365 nm, and the irradiation dose is 5000 J / m 2 , forming a cholesteric liquid crystal layer.

[0186] Example 9

[0187] This example provides a method for preparing a cholesteric liquid crystal layer.

[0188] The cholesteric liquid crystal layer has three different pitch structures in the thickness direction. The P1 liquid crystal polymer layer with a pitch of 291 nm has a thickness of 3 μm; the P2 liquid crystal polymer layer with a pitch of 335 nm has a thickness of 3.5 μm; the P3 liquid crystal polymer layer with a pitch of 392 nm has a thickness of 4 μm; the total thickness of the cholesteric liquid crystal layer is 10.5 μm.

[0189] The method for preparing the cholesteric liquid crystal layer includes:

[0190] (1) Pretreatment of the substrate layer, (2) Preparation of the liquid crystal mixture, and (3) Coating of the liquid crystal mixture are the same as in Example 9. The difference is that the P1 liquid crystal polymer layer, P2 liquid crystal polymer layer, and P3 liquid crystal polymer layer are sequentially coated on the corona-treated substrate layer. The P1 liquid crystal polymer layer is the same as the liquid crystal mixture described in Example 9. The difference between the preparation raw materials of the P2 liquid crystal polymer layer and the P1 liquid crystal polymer layer is that the content of the X13 compound (chiral compound) is 1.7%, and the content of propylene glycol monomethyl ether acetate (organic solvent) is 16.3%. The difference between the preparation raw materials of the P3 liquid crystal polymer layer and the P1 liquid crystal polymer layer is that the content of the X13 compound (chiral compound) is 1.4%, and the content of propylene glycol monomethyl ether acetate (organic solvent) is 16.6%.

[0191] Examples 10 - 15

[0192] This example provides a circular polarizer, which includes: a cholesteric liquid crystal layer, a retardation layer, a linear polarizer layer, and a viewing angle compensation layer. The cholesteric liquid crystal layer is located between the display substrate and the retardation layer, the linear polarizer layer is located on the side of the retardation layer away from the cholesteric liquid crystal layer, and the viewing angle compensation layer is located between the cholesteric liquid crystal layer and the display substrate. The compositions of the circular polarizers in Examples 10 - 15 are shown in Table 11.

[0193] Comparative Examples 1 - 2

[0194] This comparative example provides a circular polarizing plate, which includes a cholesteric liquid crystal layer, a retardation layer, a linear polarizing layer, and a viewing angle compensation layer. The compositions of the circular polarizing plates of Comparative Examples 1-2 are shown in Table 11.

[0195] Table 11 Structural compositions of different circular polarizing plates

[0196]

[0197] Example 17

[0198] This example provides a display device.

[0199] The display device in this example includes the circular polarizing plates in Examples 10-16 and Comparative Examples 1-2, and a display substrate.

[0200] When measuring the light output efficiency of the above circular polarizing plate at different viewing angles, the circular polarizing plate is attached to the display panel. The light wavelengths emitted by the display substrate include blue light with a central wavelength of 460 nm, green light with a central wavelength of 530 nm, and red light with a central wavelength of 620 nm. By measuring the light power and the light output brightness at different viewing angles, with the unit of nit, the test results are shown in Table 12.

[0201] Table 12 Light output efficiency of the circular polarizing plate at different viewing angles

[0202]

[0203] The viewing angle compensation layer is located between the cholesteric liquid crystal layer and the display substrate, and its structural design has significant advantages in improving the large viewing angle display effect of liquid crystal display devices. As shown in Table 12, Comparative Example 2 (without a viewing angle compensation layer and a cholesteric liquid crystal layer) has the lowest light output efficiency at all viewing angles, while Comparative Example 1 (with a cholesteric liquid crystal layer but without a viewing angle compensation layer) has a significantly improved light output efficiency at the normal incidence angle and small incidence angles (0°-30°), but as the viewing angle increases, the brightening efficiency decays significantly, and the display effect is poor at large viewing angles (31°-80°).

[0204] The present invention effectively solves this problem by adding a viewing angle compensation layer between the display substrate and the cholesteric liquid crystal layer. The data comparison between Examples 10 to 16 and Comparative Example 1 shows that regardless of whether the added viewing angle compensation layer is a microstructured viewing angle compensation layer (Example 14), a non-liquid crystal polymerizable coating with viewing angle compensation particles (Examples 10 to 13), a liquid crystal polymerizable coating with viewing angle compensation particles (Example 15), or a polymerizable liquid crystal coating (Example 16), it can expand the angle of the light emitted from the display substrate, redistribute the light originally concentrated in a small viewing angle range to a larger viewing angle range, thereby compensating for the light efficiency loss of the cholesteric liquid crystal layer at large viewing angles and improving the display effect of the display device at large viewing angles. In particular, the brightness of Example 12 (inorganic-organic mixture) at 0° and 80° viewing angles is 114 nit and 78 nit respectively, compared with 112 nit and 75 nit of Example 10 (inorganic substance), and the efficiency is significantly improved. This shows that the inorganic-organic mixture has a more uniform scattering effect on the emitted light through the synergistic effect of the flexibility of the organic matter and the rigidity of the inorganic matter.

[0205] In addition, the structure of the cholesteric liquid crystal layer also has a significant impact on the display performance. The brightness of Example 10 with a single pitch structure at an 80° viewing angle is 75 nit, while that of Example 11 with a triple pitch structure is increased to 92 nit. The cholesteric liquid crystal layer with a multi-pitch structure can regulate the emission of red, green, and blue spectral lights, significantly improving the light extraction efficiency of the display device. The synergistic effect of the pitch and thickness also enhances the brightening efficiency at large viewing angles. For example, the superposition of different pitch layers in Example 9 makes the total thickness reach 10.5 μm, further improving the display performance.

[0206] In summary, Example 15 (using the viewing angle compensation layer of Example 6 and the cholesteric liquid crystal layer of Example 9) exhibits the highest brightness and the gentlest attenuation in the full viewing angle range of 0° to 80°, especially with significant advantages at large angles of 31° to 80°. The synergistic effect of this viewing angle compensation particle and the liquid crystal focal conic texture realizes efficient light regulation at large viewing angles, taking into account both the positive viewing angle efficiency and the large viewing angle performance, and is very suitable for high-demand large viewing angle display scenarios. The design of the viewing angle compensation layer between the cholesteric liquid crystal layer and the display substrate not only effectively compensates for the optical path difference at large viewing angles but also significantly improves the overall performance of the display device through material and structure optimization.

[0207] The above-described embodiments are part of the embodiments of the present invention, not all of them. The detailed description of the embodiments of the present invention is not intended to limit the scope of the present invention claimed but merely represents the selected embodiments of the present invention. All other embodiments obtained by relevant deductions and substitutions made by those of ordinary skill in the art under the premise of not making creative efforts according to the concept of the present invention belong to the scope of protection of the present invention.

Claims

1. A circular polarizer based on perspective compensation, the circular polarizer being disposed on a display substrate, characterized in that, The circular polarizer includes a viewing angle compensation layer, a cholesteric liquid crystal layer, a retardation layer, and a linear polarizer layer; The cholesteric liquid crystal layer is located between the display substrate and the retardation layer, the linear polarizer layer is located on the side of the retardation layer away from the cholesteric liquid crystal layer, and the viewing angle compensation layer is located between the cholesteric liquid crystal layer and the display substrate; The viewing angle compensation layer is selected from any one of a non-liquid crystal polymerizable coating added with viewing angle compensation particles, a liquid crystal polymerizable coating added with viewing angle compensation particles, and a polymerizable liquid crystal coating; The non-liquid crystal polymerizable coating added with viewing angle compensation particles is prepared by mixing and curing viewing angle compensation particles and a non-liquid crystal polymerizable colloid, and the mass ratio of the viewing angle compensation particles to the non-liquid crystal polymerizable colloid is 0.1~1.2:1; The liquid crystal polymerizable coating added with viewing angle compensation particles is prepared by mixing viewing angle compensation particles and a liquid crystal mixture, coating the mixture on a substrate layer, and curing it, and the mass ratio of the viewing angle compensation particles to the liquid crystal mixture is 0.1~1.2:1; The polymerizable liquid crystal coating is a liquid crystal polymer layer with a chiral compound and a focal conic texture.

2. The circular polarizer based on perspective compensation according to claim 1, wherein The viewing angle compensation particles in the non-liquid crystal polymerizable coating added with viewing angle compensation particles are inorganic substances with a diameter of 10 nm to 30 μm and / or organic substances with a diameter of 1 μm to 50 μm.

3. The circular polarizer based on perspective compensation according to claim 2, wherein The inorganic substances are selected from at least one of titanium dioxide, calcium carbonate, barium sulfate, and silicon dioxide; The organic substances are selected from at least one of polymethyl methacrylate, polybutyl methacrylate, polystyrene, polymerizable liquid crystal monomers, and silicone resins.

4. The circular polarizer based on perspective compensation according to claim 1, characterized in that The non-liquid crystal polymerizable colloid in the non-liquid crystal polymerizable coating added with viewing angle compensation particles is a mixture of one or more of methyl methacrylate, butyl methacrylate, and styrene.

5. The circular polarizer based on perspective compensation according to claim 1, characterized in that, In the liquid crystal polymerizable coating added with viewing angle compensation particles, by mass, the liquid crystal mixture includes: 100~980 parts of polymerizable liquid crystal monomers, 5~300 parts of chiral compounds, 1~50 parts of photoinitiators, and 5~800 parts of organic solvents; The substrate layer is an organic film with a thickness of 5~300 μm.

6. The circular polarizer based on perspective compensation according to claim 5, wherein The polymerizable liquid crystal monomers are selected from one or more of nematic liquid crystals, discotic liquid crystals, and disc-shaped liquid crystals; The polymerizable liquid crystal monomers contain n polymerizable groups, where n≥1; The polymerizable groups are one of alkenyl, alkynyl, epoxy group, and mercapto group.

7. A display device, characterized in that, It includes the circular polarizer described in claim 1 and a display substrate.

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