Optical Modulation Devices

Abstract

The present application relates to an optical modulation device. The present application can provide an optical modulation device that has excellent optical properties such as variable transmittance and mechanical properties, while controlling light leakage in all directions in blocking mode, making it applicable to a variety of applications. The optical modulation device of the present invention includes first and second substrates, each having a first surface and a second surface, arranged opposite each other; a light modulation layer located between the first and second substrates; and a retardation film formed on the second surface of the first substrate or the second substrate, having an in-plane retardation of 100 nm to 300 nm for light with a wavelength of 550 nm.

Description

[Technical field]

[0001] This application claims priority based on Korean Patent Application No. 10-2020-0092376 filed on July 24, 2020, and the contents disclosed in the Korean patent application are incorporated herein by reference.

[0002] This application relates to light modulating devices. [Background technology]

[0003] An optical modulation device is a device that can switch between at least two different states. Recently, polymer film substrates have been used for such optical modulation devices because it is relatively easy to realize flexible elements and apply roll-to-roll processes.

[0004] In this case, when an isotropic film substrate is used as the polymer film, there are problems such as poor mechanical strength, crack generation, and shrinkage due to heat. Summary of the Invention [Problem to be solved by the invention]

[0005] However, optical modulation devices using anisotropic film substrates have problems such as a decrease in the driving performance of the device due to the phase difference of the film substrate, for example, light leakage from the side of the optical modulation device in the blocking mode.

[0006] Therefore, one object of the present application is to provide an optical modulation device that has excellent optical properties such as variable transmittance characteristics and mechanical properties, while controlling light leakage in all directions in blocking mode, making it applicable to a variety of applications. [Means for solving the problem]

[0007] The angles defined in this specification should be understood in consideration of errors such as manufacturing errors or variations. For example, the terms vertical, horizontal, orthogonal, parallel, or angle values ​​in this specification mean substantially vertical, horizontal, orthogonal, parallel, or angle values ​​within a range that does not impair the intended effect, and each of the above cases may include an error within about ±15 degrees, an error within about ±14 degrees, an error within about ±13 degrees, an error within about ±12 degrees, an error within about ±11 degrees, an error within about ±10 degrees, an error within about ±9 degrees, an error within about ±8 degrees, an error within about ±7 degrees, an error within about ±6 degrees, an error within about ±5 degrees, an error within about ±4 degrees, an error within about ±3 degrees, an error within about ±2 degrees, an error within about ±1 degree, or an error within about ±0.5 degrees.

[0008] In the present specification, when the measurement temperature affects a physical property, the physical property is measured at room temperature unless otherwise specified.

[0009] The term "room temperature" as used herein refers to a temperature in a natural state that is not particularly heated or cooled, and may mean any one of temperatures within a range of about 10° C. to 30° C., for example, a temperature of about 15° C. or higher, 18° C. or higher, 20° C. or higher, or about 23° C. or higher, and about 27° C. or lower. Furthermore, unless otherwise specified, the unit of temperature referred to in the present specification is ° C.

[0010] In this specification, the in-plane retardation (Rin) may mean a value calculated by the following Equation 4, and the thickness direction retardation (Rth) may mean a value calculated by the following Equation 5.

[0011] [Formula 4]

[0012] Rin = d × (nx-ny)

[0013] [Formula 5]

[0014] Rth = d × (nz-ny)

[0015] In Formula 4 and Formula 5, Rin may be an in-plane retardation, Rth may be a thickness direction retardation, d may be a layer thickness, nx may be a refractive index of the layer in a slow axis direction, ny may be a refractive index of the layer in a fast axis direction which is a refractive index in an in-plane direction perpendicular to the slow axis direction, and nz may be a refractive index in a thickness direction of the layer.

[0016] The term "layer" refers to a layer for which the in-plane retardation and / or thickness retardation is to be measured. The layer may be, for example, a polarizing layer, a polymer film, a retardation film, an optically anisotropic layer, or a light modulating layer.

[0017] The term tilt angle referred to in this specification is defined as follows unless otherwise specified. When the plane formed by the x-axis and y-axis in FIG. 3 is taken as a reference plane (for example, the reference plane may be the surface of a polarizing layer, a polymer film, a retardation film, an optically anisotropic layer, or a light modulation layer of a light modulation device), the angle formed with respect to the z-axis, which is the normal to the reference plane, as shown in FIG. 3 is defined as the tilt angle (the tilt angle at point P in FIG. 3 is Θ). When the plane formed by the x-axis and y-axis in FIG. 3 is taken as a reference plane (for example, the reference plane may be the surface of a polarizing layer, a polymer film, a retardation film, an optically anisotropic layer, or a light modulation layer of a light modulation device), the angle formed with respect to the corresponding x-axis when the x-axis of the reference plane is set to 0 degrees is defined as the radial angle as shown in FIG. 3 (the radial angle at point P in FIG. 3 is Φ). The x-axis of the reference plane in the above may refer to, for example, the horizontal axis of the reference plane.

[0018] The phase difference, refractive index, refractive index anisotropy, transmittance, and the like referred to in this specification are physical quantities for light with a wavelength of about 550 nm, unless otherwise specified.

[0019] Unless otherwise specified, the angle between any two directions mentioned in this specification may be the acute angle between the acute or obtuse angles between the two directions, or the smaller angle between the angles measured in the clockwise and counterclockwise directions. Therefore, unless otherwise specified, the angles mentioned in this specification are positive numbers. However, in some cases, to indicate the measurement direction between angles measured in the clockwise or counterclockwise directions, the angle measured in the clockwise direction may be expressed as a positive number and the angle measured in the counterclockwise direction may be expressed as a negative number.

[0020] The present application may be directed to, for example, a light modulation device including a first and a second substrate, each having a first surface and a second surface, and disposed so that the first surfaces face each other, and a light modulation layer present between the first and second substrates. A retardation film having an in-plane retardation of 100 nm to 300 nm for light with a wavelength of 550 nm may be formed on the second surface of the first substrate or the second substrate. For example, the first surface may mean any one of the main surface of the layer and the surface opposite thereto, and the second surface may mean the other one of the main surface of the layer and the surface opposite thereto. In another example, the first surface may mean the direction toward the light modulation layer of each layer, and the second surface may mean the opposite direction of the first surface. In the present specification, the layer may be, for example, a first substrate, a second substrate, a retardation film, an optically anisotropic layer, an adhesive layer (or a pressure-sensitive adhesive layer), a liquid crystal alignment film, and / or a polarizing layer.

[0021] The light modulation device of the present application may, for example, include a retardation film on the second surface of the first substrate or the second substrate. The retardation film may be preferably disposed on only one of the second surface of the first substrate or the second surface of the second substrate.

[0022] The retardation film may have an in-plane retardation within a range of 100 nm to 300 nm with respect to light having a wavelength of 550 nm, for example. In other examples, the in-plane retardation may be 105 nm or more, 110 nm or more, 115 nm or more, 120 nm or more, 125 nm or more, 130 nm or more, 135 nm or more, 140 nm or more, 145 nm or more, 150 nm or more, 155 nm or more, 160 nm or more, 165 nm or more, 170 nm or more, 175 nm or more, 180 nm or more, 185 nm or more, 190 nm or more, 195 nm or more, 200 nm or more, 205 nm or more, 210 nm or more, 215 nm or more, 220 nm or more, 225 nm or more, 230 nm or more, 235 nm or more, 240 nm or more, 245 nm or more, 250 nm or more, 255 nm or more, 260 nm or more, 265 nm or more, or 270 nm or more, or 295 nm or less, 290 nm or less, 285 nm or less, or 280 nm or less.

[0023] For example, the retardation film may have a thickness direction retardation of about 0 nm or more than 0 nm for light having a wavelength of 550 nm. In this specification, the retardation film may have a thickness direction retardation of about 0 nm or more than 0 nm for light having a wavelength of 550 nm, which may include a value having an error of ±5 nm, ±4 nm, ±3 nm, ±2 nm, ±1 nm, ±0.9 nm, ±0.8 nm, ±0.7 nm, ±0.6 nm, ±0.5 nm, ±0.4 nm, ±0.3 nm, ±0.2 nm, or ±0.1 nm with respect to 0 nm or a value exceeding 0 nm.

[0024] The light modulation device of the present application can control omnidirectional light leakage in blocking mode by introducing, at appropriate positions, a retardation film having an in-plane retardation as described above and / or the characteristics described below.

[0025] The retardation film may be, for example, a film satisfying the following formula 1 or 2.

[0026] [Formula 1]

[0027] nx>ny≒nz

[0028] [Formula 2]

[0029] nx≒nz>ny

[0030] In Formula 1 and Formula 2, nx may be the refractive index of the retardation film for light with a wavelength of 550 nm in the slow axis direction, ny may be the refractive index of the retardation film for light with a wavelength of 550 nm in the fast axis direction, and nz may be the refractive index of the retardation film in the thickness direction.

[0031] As used herein, ≈ may mean substantially the same.

[0032] The retardation film may be, for example, a half-wave plate (HWP) or a quarter-wave plate (QWP). In this specification, the term HWP means a wave plate having a half-wave phase retardation characteristic, and the term QWP means a wave plate having a quarter-wave phase retardation characteristic. In this specification, the n-wavelength phase retardation characteristic means a characteristic that can delay the phase of incident light by n times the wavelength of the incident light at least within a certain wavelength range. Therefore, the half-wavelength phase retardation characteristic may mean a characteristic that can delay the phase of incident light by half the wavelength of the incident light at least within a certain wavelength range, and the quarter-wavelength phase retardation characteristic may mean a characteristic that can delay the phase of incident light by 1 / 4 times the wavelength of the incident light at least within a certain wavelength range.

[0033] The retardation film may have a thickness in the range of, for example, 20 μm to 70 μm. Other examples include, but are not limited to, 21 μm or more, 22 μm or more, 23 μm or more, 24 μm or more, 25 μm or more, 26 μm or more, 27 μm or more, 28 μm or more, 29 μm or more, 30 μm or more, 31 μm or more, 32 μm or more, 33 μm or more, 34 μm or more, 35 μm or more, 36 μm or more, 37 μm or more, 38 μm or more, 39 μm or more, 40 μm or more, 41 μm or more, 42 μm or more, 43 μm or more. or less than 44 μm or less, or less than 69 μm, 68 μm, 67 μm, 66 μm, 65 μm, 64 μm, 63 μm, 62 μm, 61 μm, 60 μm, 59 μm, 58 μm, 57 μm, 56 μm, 55 μm, 54 μm, 53 μm, 52 μm, 51 μm, 50 μm, 49 μm, 48 μm, 47 μm, or 46 μm.

[0034] The retardation film may have a refractive index anisotropy (Δn) in the range of 0.1 to 1.5, for example. The refractive index anisotropy (Δn) in the present application may be the difference (ne-no) between the extraordinary refractive index (ne, extraordinary refractive index) and the ordinary refractive index (no, ordinary refractive index). In the present specification, the ne may be, for example, nz, and the no may be, for example, nx and / or ny. That is, the refractive index anisotropy (Δn) in the present application may be, for example, nz-nx or nz-ny. The refractive index anisotropy (Δn) may be, for example, 0.2 or more, 0.3 or more, 0.4 or more, 0.5 or more, or 0.6 or more, or 1.4 or less, 1.3 or less, 1.2 or less, 1.1 or less, 1.0 or less, 0.9 or less, or 0.8 or less.

[0035] The retardation film may also have an average refractive index in the range of 1.0 to 2.0. The average refractive index in the present application may mean the average value ((ne+no) / 2) of the extraordinary refractive index (ne) and the ordinary refractive index (no). In the present specification, the average refractive index may be, for example, (nx+nz) / 2 or (ny+nz) / 2. In other examples, the average refractive index may be 1.1 or more, 1.2 or more, 1.3 or more, 1.4 or more, or 1.5 or more, or 1.9 or less, 1.8 or less, 1.7 or less, or 1.6 or less.

[0036] In the present application, the extraordinary refractive index (ne) and the ordinary refractive index (no) can be confirmed using an Abbe refractometer, and the specific method thereof is in accordance with the method disclosed in Evaluation Example 4 below.

[0037] The present application provides an optical modulation device having excellent mechanical properties and a desired optical compensation effect, for example, an effect of controlling omnidirectional light leakage in a blocking mode, by appropriately introducing a retardation film having an in-plane retardation within the above range and / or satisfying Formula 1 or Formula 2, etc., at the above-mentioned position.

[0038] The inventors have confirmed that by arranging a retardation film having the above-mentioned characteristics and an optically anisotropic layer having the characteristics described below in appropriate positions, it is possible to provide an optical modulation device that has excellent optical properties such as transmittance variable characteristics and mechanical properties, while controlling light leakage in all directions in a blocking mode, and is applicable to a variety of applications.

[0039] The optically anisotropic layer may be, for example, included at least one of between the light modulation layer and the first substrate or between the light modulation layer and the second substrate. In this specification, "included at least one of between the light modulation layer and the first substrate or between the light modulation layer and the second substrate" may mean that the optically anisotropic layer is disposed between the light modulation layer and the first substrate and between the light modulation layer and the second substrate, or the optically anisotropic layer is disposed at any one of between the light modulation layer and the first substrate or between the light modulation layer and the second substrate.

[0040] The optically anisotropic layer may be, for example, a -C plate satisfying the following mathematical formula 3.

[0041] [Formula 3]

[0042] nz <ny≒nx

[0043] In Equation 3, nx may be the refractive index of the optically anisotropic layer for light with a wavelength of 550 nm in the slow axis direction, ny may be the refractive index of the optically anisotropic layer for light with a wavelength of 550 nm in the fast axis direction, and nz may be the refractive index of the optically anisotropic layer in the thickness direction.

[0044] The optically anisotropic layer may have a thickness direction retardation of -100nm to -350nm for light with a wavelength of 550nm. The thickness direction retardation may be -110nm or less, -120nm or less, -130nm or less, -140nm or less, -150nm or less, -160nm or less, -170nm or less, -180nm or less, -190nm or less, -200nm or less, or -210nm or less, or -340nm or more, -330nm or more, -320nm or more, -310nm or more, -300nm or more, -290nm or more, -280nm or more, -270nm or more, -260nm or more, -250nm or more, -240nm or more, or -230nm or more.

[0045] The optically anisotropic layer may have an in-plane retardation of 10 nm or less for light having a wavelength of 550 nm, for example. In other examples, the in-plane retardation may be 9 nm or less, 8 nm or less, 7 nm or less, 6 nm or less, 5 nm or less, 4 nm or less, 3 nm or less, 2 nm or less, or 1 nm or less, and preferably 0 nm.

[0046] In the present application, the optically anisotropic layer may be any commonly used liquid crystal film or polymer film without limitation as long as it exhibits the above-mentioned characteristics. The optically anisotropic layer may be formed by mixing polyamide in a solvent, for example. The polyamide may be formed by polymerizing 2,2'-bis(trifluoromethyl)-5,5'-biphenyldiamine with isophthalic acid and / or terephthalic acid, for example. The solvent may be dimethylacetamide, for example. The polyamide may be included in the solvent in a range of about 4% to 10% by weight, for example, 4.5% by weight or more, 5% by weight or more, or 9% by weight or less, 8% by weight or less, 7% by weight or less, 6% by weight or less, or 5.5% by weight or less.

[0047] In one example, a solution formed by mixing polyamide in a solvent can be applied onto a polymer film or a conductive layer described below, for example, by a bar coating method, a slot-die coating method, a gravure coating method, etc.

[0048] The coating layer formed by the coating may be cured by heat curing or UV curing. In one example, the optically anisotropic layer of the present application may be a layer formed by applying heat in the range of about 50°C to 150°C for a time period in the range of about 5 minutes to 30 minutes to the coating layer to cure it. In another example, the curing temperature may be 60°C or more, 70°C or more, 80°C or more, or 90°C or more, or 140°C or less, 130°C or less, 120°C or less, or 110°C or less, and the curing time may be about 6 minutes or more, 7 minutes or more, 8 minutes or more, or 9 minutes or more, or 25 minutes or less, 20 minutes or less, or 15 minutes or less, but is not limited thereto.

[0049] The optically anisotropic layer may have a refractive index anisotropy (Δn) in the range of, for example, 0.01 to 0.15. Other examples of the refractive index anisotropy (Δn) include 0.02 or more, 0.03 or more, 0.04 or more, 0.05 or more, 0.06 or more, 0.07 or more, 0.08 or more, or 0.09 or more, or 0.14 or less, 0.13 or less, 0.12 or less, or 0.11 or less.

[0050] The optically anisotropic layer may have an average refractive index in the range of 1.0 to 2.0, for example. The average refractive index may be, for example, 1.1 or more, 1.2 or more, 1.3 or more, 1.4 or more, 1.5 or more, or 1.6 or more, or 1.9 or less, 1.8 or less, or 1.7 or less.

[0051] In the present application, the optically anisotropic layer may have a thickness in the range of, for example, 0.1 μm to 10 μm. In other examples, the thickness may be about 0.2 μm or more, about 0.3 μm or more, about 0.4 μm or more, about 0.5 μm or more, about 0.6 μm or more, about 0.7 μm or more, about 0.8 μm or more, about 0.9 μm or more, about 1 μm or more, about 1.1 μm or more, about 1.2 μm or more, about 1.3 μm or more, about 1.4 μm or more, about 1.5 μm or more, about 1.6 μm or more, about 1.7 μm or more, about 1.8 μm or more, or about 1.9 μm or more, or about 9 μm or less, about 8 μm or less, about 7 μm or less, about 6 μm or less, about 5 μm or less, about 4 μm or less, or about 3 μm or less.

[0052] By disposing a retardation film and / or an optically anisotropic layer having the above-mentioned characteristics at an appropriate position of the light modulation device, the present application can control the side light leakage in blocking mode while solving the problem of the compensation effect being distorted due to the optical properties of the polymer film substrate described below.

[0053] In the present application, the first and / or second substrate may be a polymer film. The polymer film may be isotropic or anisotropic, but is preferably an anisotropic polymer film in terms of mechanical strength, crack generation control, heat shrinkage control, etc.

[0054] The first and / or second polymer film may have an in-plane retardation of 500 nm or more at a wavelength of 550 nm, for example. In other examples, the in-plane retardation may be 1000 nm or more, 2000 nm or more, 3000 nm or more, 4000 nm or more, 5000 nm or more, 6000 nm or more, 7000 nm or more, 8000 nm or more, 9000 nm or more, or 10000 nm or more, or 50000 nm or less, 40000 nm or less, 30000 nm or less, 20000 nm or less, or 15000 nm or less, but is not limited thereto.

[0055] The first and / or second polymer film may have a thickness direction retardation of 3000 nm or less at a wavelength of 550 nm. In another example, the thickness direction retardation may be 2900 nm or less, 2800 nm or less, 2700 nm or less, 2600 nm or less, 2500 nm or less, 2400 nm or less, 2300 nm or less, 2200 nm or less, 2100 nm or less, 2000 nm or less, 1900 nm or less, 1800 nm or less, 1700 nm or less, 1600 nm or less, 1500 nm or less, 1400 nm or less, 1300 nm or less, 1200 nm or less, 1100 nm or less, or 1000 nm or less, or about 100 nm or more, 200 nm or more, 300 nm or more, 400 nm or more, or 500 nm or less.

[0056] Films having such a high retardation are known in the art, and such films show not only large optical anisotropy but also large asymmetry in mechanical properties due to high stretching during the manufacturing process. Examples of the retardation films known in the art include, but are not limited to, polyethylene terephthalate (PET) films, cyclo-olefin polymer (COP) films, cyclo-olefin copolymer (COC) films, polycarbonate (PC), polypropylene (PP) films, polysulfone (PSF) films, and polymethylmethacrylate (PMMA) films. In the present application, the first and / or second polymer films may be the same or different and may be appropriately selected from the known films in consideration of the desired effects.

[0057] In the present application, the first and second polymer films may be selected so that the value of P in the following Equation 6 is 0.3 or more in order to maximize the effect of controlling the rainbow current.

[0058] [Formula 6]

[0059]

number

[0060] In the formula 6, WA may represent the thickness of the first substrate, WB may represent the thickness of the second substrate, and min(WA, WB) may represent the smaller value of WA or WB. In other examples, the value of P in the formula 6 may be less than 1, less than 0.95, less than 0.9, less than 0.85, or less than 0.8, or may be 0.35 or more, 0.4 or more, 0.45 or more, 0.5 or more, 0.55 or more, 0.6 or more, 0.65 or more, or 0.7 or more, but is not limited thereto.

[0061] In the present application, the WA value of P in the above formula 6 may be, for example, within a range of 50 μm to 100 μm. In other examples, the WA value may be 55 μm or more, 60 μm or more, 65 μm or more, 70 μm or more, or 75 μm or more, or 95 μm or less, 90 μm or less, or 85 μm or less. In the present application, the WB value of P in the above formula 6 may be, for example, within a range of 120 μm to 180 μm. In other examples, the WB value may be 125 μm or more, 130 μm or more, 135 μm or more, or 140 μm or more, or 175 μm or less, 170 μm or less, 165 μm or less, 160 μm or less, 155 μm or less, or 150 μm or less.

[0062] The present application provides an optical modulation device that can be used for various applications by introducing a polymer film having, for example, the above-mentioned in-plane retardation, thickness, etc. as the first and / or second polymer film, and disposing a retardation film and / or an optically anisotropic layer having the above-mentioned characteristics at an appropriate position, while having excellent optical properties such as variable transmittance characteristics and mechanical properties, and by controlling light leakage in all directions in blocking mode.

[0063] For example, the present application may further include a polarizing layer formed on one or more of the second surfaces of the first and / or second substrates. In the present application, the polarizing layer may be formed only on the second surface of the first substrate, only on the second surface of the second substrate, or on both the second surfaces of the first and second substrates, and preferably on the second surfaces of the first and second substrates.

[0064] In this specification, the polarizing layer may refer to an element that converts natural light or non-polarized light into polarized light. The polarizing layer may be, for example, a linear polarizing layer. In this specification, the linear polarizing layer refers to a case where selectively transmitted light is linearly polarized light that vibrates in one direction, and selectively absorbed or reflected light is linearly polarized light that vibrates in a direction perpendicular to the vibration direction of the linearly polarized light. That is, the linear polarizer may have a transmission axis and an absorption axis or reflection axis perpendicular to the plane direction.

[0065] The polarizing layer may be an absorptive polarizing layer or a reflective polarizing layer. The absorptive polarizing layer may be, for example, a polarizing layer obtained by dyeing a polymer stretched film such as a PVA (PVA in this specification means polyvinyl alcohol) stretched film with iodine, or a guest-host polarizing layer in which a liquid crystal polymerized in an oriented state serves as a host and an anisotropic dye aligned according to the orientation of the liquid crystal serves as a guest, but is not limited thereto. The reflective polarizing layer may be, for example, a reflective polarizing layer known as a so-called DBEF (Dual Brightness Enhancement Film) or a reflective polarizing layer formed by coating a liquid crystal compound such as LLC (Lyotropic liquid crystal), but is not limited thereto.

[0066] In the present application, the polarizing layer may have a thickness in the range of, for example, 80 μm to 200 μm. In another example, the thickness of the polarizing layer may be 90 μm or more, 100 μm or more, 110 μm or more, 120 μm or more, or 130 μm or more, or 190 μm or less, 180 μm or less, 170 μm or less, 160 μm or less, or 150 μm or less.

[0067] In the present application, the term "light modulating device" may refer to a device capable of switching between at least two or more different light states. The different light states may refer to states in which at least one of transmittance, haze, and color is different from each other. The light modulating layer may be present between the first and second substrates disposed opposite to each other, as described above.

[0068] In the present application, the light modulation layer may refer to, for example, a liquid crystal layer that includes a liquid crystal compound and can control the alignment state of the liquid crystal compound through application of an external signal. As the liquid crystal compound, any type of liquid crystal compound may be used as long as the alignment direction can be changed by application of an external signal. As the liquid crystal compound, for example, a nematic liquid crystal compound, a smectic liquid crystal compound, or a cholestric liquid crystal compound may be used. In addition, the liquid crystal compound may be, for example, a compound that does not have a polymerizable group or a crosslinkable group, or a compound that has a polymerizable group or a crosslinkable group but is in a non-polymerized or non-crosslinked state so that the alignment direction can be changed by application of an external signal.

[0069] The light modulating layer may, for example, include a liquid crystal compound having a negative dielectric anisotropy, or the light modulating layer may exhibit the dielectric anisotropy mentioned above. The absolute value of the dielectric anisotropy may be appropriately selected in consideration of the object of the present application. The term "dielectric anisotropy (Δε)" may refer to the difference (ε / / -ε⊥) between the horizontal dielectric constant (ε / / ) and the vertical dielectric constant (ε⊥). In this specification, the term horizontal dielectric constant (ε / / ) refers to the dielectric constant value measured along the direction of an electric field when a voltage is applied so that the direction of the electric field caused by the applied voltage is substantially horizontal to the director of liquid crystal molecules, and the term vertical dielectric constant (ε⊥) refers to the dielectric constant value measured along the direction of an electric field when a voltage is applied so that the direction of the electric field caused by the applied voltage is substantially perpendicular to the director of liquid crystal molecules.

[0070] The light modulation layer may include a liquid crystal compound having a refractive index anisotropy (Δn) in the range of about 0.04 to 0.15, or the light modulation layer may exhibit the above-mentioned refractive index anisotropy. Other examples of the refractive index anisotropy (Δn) include about 0.14 or less, 0.13 or less, 0.12 or less, 0.11 or less, or 0.05 or more, 0.06 or more, or 0.07 or more.

[0071] The light modulation layer may have an average refractive index in the range of 1.0 to 2.0, for example. In other examples, the average refractive index may be 1.1 or more, 1.2 or more, 1.3 or more, 1.4 or more, or 1.5 or more, or 1.9 or less, 1.8 or less, 1.7 or less, or 1.6 or less.

[0072] The driving mode of the light modulation layer may be, for example, a reversed twisted nematic (TN) mode, a reversed super twisted nematic (STN) mode, a vertical alignment (VA) mode, a multi-domain vertical alignment (MVA) mode, a patterned vertical alignment (PVA) mode, a hybrid aligned nematic (HAN) mode, etc.

[0073] The light modulating layer of the present application may further include a dichroic dye together with the liquid crystal compound in terms of controlling the light transmittance variable property. In this specification, the term "dye" may mean a material capable of intensively absorbing and / or transforming light in at least a part or the entire range within the visible light region, for example, a wavelength range of 400 nm to 700 nm, and the term "dichroic dye" may mean a material capable of anisotropic absorption of light in at least a part or the entire range of the visible light region. Examples of such dyes include, but are not limited to, azo dyes and anthraquinone dyes.

[0074] In one example, the light modulation layer may be a liquid crystal layer containing a liquid crystal compound and a dichroic dye, so-called a guest host liquid crystal layer. The term "GHLC layer" may refer to a functional layer in which dichroic dyes are arranged together with the alignment of liquid crystals, and which exhibits anisotropic light absorption characteristics in the alignment direction of the dichroic dyes and in a direction perpendicular to the alignment direction. For example, a dichroic dye is a material whose light absorption rate changes depending on the polarization direction, and if it has a high absorption rate for light polarized in the long axis direction, it can be called a p-type dye, and if it has a high absorption rate for light polarized in the short axis direction, it can be called an n-type dye. In one example, when a p-type dye is used, polarized light vibrating in the long axis direction of the dye is absorbed, and polarized light vibrating in the short axis direction of the dye can be transmitted because it is less absorbed.

[0075] The ratio of the dichroic dye contained in the guest-host liquid crystal layer is not particularly limited and may be set within an appropriate range in consideration of the desired transmittance. In general, the dichroic dye may be contained in the light modulating layer at a ratio of about 0.1% by weight to about 4% by weight in consideration of the miscibility of the dichroic dye and the liquid crystal compound.

[0076] The present application may be directed to a light modulation device designed to adjust the alignment of the liquid crystal compound in the light modulation layer so that the initial alignment is vertical alignment and the vertical alignment state can be changed to a horizontal alignment state by application of an external signal. The horizontal alignment may be a twisted alignment. The initial alignment is an alignment state when no external signal is applied to the light modulation layer. In this specification, the term vertical alignment refers to a state in which the director of the light modulation layer or the director of the liquid crystal compound in the light modulation layer is aligned substantially perpendicular to the plane of the light modulation layer, and for example, the angle between the z axis, which is the normal to the reference plane of the light modulation layer, and the director may be within a range of about 80 degrees to 100 degrees, or 85 degrees to 95 degrees, or about 90 degrees. The term horizontal alignment refers to a state in which the director of the light modulation layer or the director of the liquid crystal compound in the light modulation layer is aligned substantially parallel to the reference plane of the light modulation layer, and for example, the angle between the director and the reference plane of the light modulation layer may be within a range of about 0 degrees to 10 degrees, or about 0 degrees to 5 degrees, or about 0 degrees.

[0077] In this specification, the term director of the light modulation layer or director of the liquid crystal compound may refer to the optical axis or slow axis of the light modulation layer. For example, the optical axis or slow axis may refer to the long axis direction when the liquid crystal molecule is rod-shaped, may refer to the axis normal to the disc plane when the liquid crystal molecule is discotic, and may refer to the sum of vectors such as directors of the liquid crystal compounds when the light modulation layer contains a plurality of liquid crystal compounds with different directors.

[0078] The present application may be directed, for example, to a light modulation device designed to adjust the alignment of liquid crystal compounds in the light modulation layer so that the initial alignment is vertical alignment and the vertical alignment state can be changed to a horizontal alignment state by application of an external signal.

[0079] The light modulating layer may be designed to realize, for example, a twisted alignment mode, which may refer to a helical structure in which the directors of the liquid crystal compound are aligned in layers while being twisted along a virtual helical axis.

[0080] The twist alignment mode may be embodied as at least a horizontal alignment mode in one example, and in the case of a vertical alignment mode, the director of the light modulation layer or the director of the liquid crystal compound in the light modulation layer may be arranged substantially perpendicular to the plane of the light modulation layer without being twisted. The horizontal twist alignment mode may mean, for example, a state in which each liquid crystal compound is horizontally aligned and twisted along a helical axis to form a layer.

[0081] In the horizontal twist alignment mode, the ratio (d / p) of the thickness (d, cell gap) of the light modulation layer to the pitch p may be, for example, 1 or less. If the ratio (d / p) exceeds 1, even in the initial vertical alignment mode, a phenomenon in which the liquid crystal compound is twisted along the helical axis may occur, and problems such as finger domains may occur, so it may be adjusted to the above range as much as possible. In other examples, the ratio (d / p) may be about 0.95 or less, about 0.9 or less, about 0.85 or less, about 0.8 or less, about 0.75 or less, about 0.7 or less, about 0.65 or less, about 0.6 or less, about 0.55 or less, about 0.5 or less, or about 0.45 or less, or about 0.1 or more, about 1.15 or more, about 0.2 or more, about 0.25 or more, or about 0.3 or more. In the above, the thickness d of the light modulation layer may have the same meaning as the cell gap in the light modulation device.

[0082] The pitch p of the light modulation layer in the horizontal twist alignment mode can be measured using a measurement method that utilizes a wedge cell, specifically, the method described in "Simple method for accurate measurements of the cholesteric pitch using a stripe-wedge Grandjean-Cano cell" by D. Podolskyy et al. (Liquid Crystals, Vol. 35, No. 7, July 8, 2008, 789-791).

[0083] The light modulating layer may further include a so-called chiral dopant so that the light modulating layer can realize a horizontal twist mode.

[0084] The chiral dopant that may be included in the light modulation layer may be any chiral dopant that can induce the desired twisting without damaging the liquid crystal property, for example, nematic regularity. The chiral dopant for inducing the rotation of the liquid crystal molecules must at least have chirality in its molecular structure. Examples of the chiral dopant include compounds having one or more asymmetric carbons, compounds having an asymmetric point on a heteroatom such as chiral amine or chiral sulfoxide, or compounds having an axially asymmetric, optically active site such as cumulene or binaphthol. The chiral dopant may be, for example, a low molecular weight compound having a molecular weight of 1,500 or less. As the chiral dopant, commercially available chiral nematic liquid crystals, for example, chiral dopant liquid crystal S811 available from Merck or LC756 from BASF, etc., can be used.

[0085] The ratio of the chiral dopant to be applied is not particularly limited as long as the desired ratio (d / p) can be achieved. In general, the content (wt%) of the chiral dopant is calculated by the formula 100 / (HTP (Helixcal Twisting power)×pitch (nm) and can be selected at an appropriate ratio taking into consideration the desired pitch p. In one example, the chiral dopant can be included so that the pitch p is within a range of about 10 μm to 50 μm. In another example, the chiral dopant can be included within an appropriate range so that the pitch is about 11 μm or more, 12 μm or more, 13 μm or more, 14 μm or more, 15 μm or more, 16 μm or more, 17 μm or more, 18 μm or more, or 19 μm or more, or 45 μm or less, 40 μm or less, 35 μm or less, 30 μm or less, 25 μm or less, 24 μm or less, 23 μm or less, 22 μm or less, or 21 μm.

[0086] The thickness of the light modulation layer of the present application may be appropriately selected in consideration of the purpose of the present application. In one example, the thickness of the light modulation layer may be about 15 μm or less. By controlling the thickness in this manner, a device having a large difference in transmittance between a transmission mode and a blocking mode, i.e., a device having excellent transmittance variable characteristics, may be realized. In other examples, the thickness may be about 14 μm or less, 13 μm or less, 12 μm or less, 11 μm or less, 10 μm or less, 9 μm or less, 8 μm or less, or 7 μm or less, or 1 μm or more, 2 μm or more, 3 μm or more, 4 μm or more, or 5 μm or more, but is not limited thereto.

[0087] By introducing the above-mentioned light modulation layer at an appropriate position together with the above-mentioned retardation film and / or optically anisotropic layer, the present application can provide a light modulation device that has excellent transmittance variable characteristics, excellent mechanical properties, and controlled omnidirectional light leakage in blocking mode.

[0088] The light modulation device of the present application may, for example, include an adhesive layer or a pressure-sensitive adhesive layer on the first surface of the first substrate. In one example, the adhesive layer or the pressure-sensitive adhesive layer may include an adhesive or a pressure-sensitive adhesive having a vertical alignment force. In this specification, the term adhesive or a pressure-sensitive adhesive having a vertical alignment force may refer to a material that simultaneously has a vertical alignment force and an adhesive force (or adhesive force) to liquid crystal molecules.

[0089] In the present application, the adhesive or pressure-sensitive adhesive having vertical alignment power may be, for example, a silicone adhesive or silicone pressure-sensitive adhesive. The silicone adhesive or silicone pressure-sensitive adhesive may be a cured product of a composition containing a curable silicone compound. The type of the curable silicone compound is not particularly limited, and may be, for example, a heat-curable silicone compound or an ultraviolet-curable silicone compound.

[0090] In one embodiment, the curable silicone composition is an addition-curable silicone composition, and can include (1) an organopolysiloxane containing two or more alkenyl groups in the molecule and (2) an organopolysiloxane containing two or more silicon-bonded hydrogen atoms in the molecule. The silicone compound can form a cured product by addition reaction in the presence of a catalyst such as a platinum catalyst.

[0091] The (1) organopolysiloxane is a main component constituting a silicone cured product, and contains at least two alkenyl groups in one molecule. Specific examples of the alkenyl group include vinyl, allyl, butenyl, pentenyl, hexenyl, and heptenyl groups, among which vinyl groups are usually used, but are not limited thereto. In the (1) organopolysiloxane, the bonding position of the alkenyl group is not particularly limited. For example, the alkenyl group may be bonded to the end of an increased branched chain and / or to a side chain of a branched chain. In the (1) organopolysiloxane, examples of the substituents that may be contained in addition to the alkenyl include alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, and heptyl; aryl groups such as phenyl, tolyl, xylyl, and naphthyl; aralkyl groups such as benzyl and phenethyl; and halogen-substituted alkyl groups such as chloromethyl, 3-chloropropyl, and 3,3,3-trifluoropropyl. Of these, methyl and phenyl groups are usually used, but the present invention is not limited to these.

[0092] The molecular structure of the organopolysiloxane (1) is not particularly limited, and may have any shape, such as linear, branched, cyclic, network, or linear with some branching, etc. Of the molecular structures described above, those having a linear molecular structure are usually used, but are not limited thereto.

[0093] More specific examples of the organopolysiloxane (1) include a dimethylsiloxane-methylvinylsiloxane copolymer having both branched chain ends blocked with trimethylsiloxane groups, a methylvinylpolysiloxane having both branched chain ends blocked with trimethylsiloxane groups, a dimethylsiloxane-methylvinylsiloxane-methylphenylsiloxane copolymer having both branched chain ends blocked with trimethylsiloxane groups, a dimethylpolysiloxane having both branched chain ends blocked with dimethylvinylsiloxane groups, a methylvinylpolysiloxane having both branched chain ends blocked with dimethylvinylsiloxane groups, a dimethylsiloxane-methylvinylsiloxane copolymer having both branched chain ends blocked with dimethylvinylsiloxane groups, a dimethylsiloxane-methylvinylsiloxane-methylphenylsiloxane copolymer having both branched chain ends blocked with dimethylvinylsiloxane groups, 1 2SiO 2 / 2 Siloxane units represented by and R 1 2R 2 SiO 1 / 2 The siloxane unit represented by and SiO 4 / 2 Organopolysiloxane copolymers containing siloxane units represented by R 1 2R 2 SiO 1 / 2 The siloxane unit represented by and SiO 4 / 2 Organopolysiloxane copolymers containing siloxane units represented by R 1 R 2 SiO 2 / 2 Siloxane units represented by and R 1 SiO 3 / 2 Siloxane units denoted by R 2 SiO 3 / 2 and mixtures of two or more of the above. 1is a hydrocarbon group other than an alkenyl group, and specifically may be an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, or a heptyl group; an aryl group such as a phenyl group, a tolyl group, a xylyl group, or a naphthyl group; an aralkyl group such as a benzyl group or a phenethyl group; or a halogen-substituted alkyl group such as a chloromethyl group, a 3-chloropropyl group, or a 3,3,3-trifluoropropyl group. 2 is an alkenyl group, and specifically may be a vinyl group, an allyl group, a butenyl group, a pentenyl group, a hexenyl group, a heptenyl group, or the like.

[0094] In the addition curable silicone composition, the (2) organopolysiloxane can crosslink the (1) organopolysiloxane. In the (2) organopolysiloxane, the bond position of the hydrogen atom is not particularly limited, and may be bonded to, for example, the end of a branched chain and / or a side chain. In the (2) organopolysiloxane, the type of substituent that may be contained in addition to the silicon-bonded hydrogen atom is not particularly limited, and examples thereof include alkyl groups, aryl groups, aralkyl groups, and halogen-substituted alkyl groups, as mentioned in the (1) organopolysiloxane, and among these, methyl groups or phenyl groups are usually used, but are not limited thereto.

[0095] The molecular structure of the (2) organopolysiloxane is not particularly limited, and may have any shape, such as linear, branched, cyclic, network, or partially branched linear, etc. Among the molecular structures described above, those having a linear molecular structure are usually used, but are not limited thereto.

[0096] More specific examples of the organopolysiloxane (2) include methylhydrogenpolysiloxanes blocked at both branched chain terminals with trimethylsiloxane groups, dimethylsiloxane-methylhydrogen copolymers blocked at both branched chain terminals with trimethylsiloxane groups, dimethylsiloxane-methylhydrogensiloxane-methylphenylsiloxane copolymers blocked at both branched chain terminals with trimethylsiloxane groups, dimethylpolysiloxanes blocked at both branched chain terminals with dimethylhydrogensiloxane groups, dimethylsiloxane-methylphenylsiloxane copolymers blocked at both branched chain terminals with dimethylhydrogensiloxane groups, methylphenylpolysiloxanes blocked at both branched chain terminals with dimethylhydrogensiloxane groups, R 1 3SiO 1 / 2 Siloxane units represented by and R 1 2HSiO 1 / 2 The siloxane unit represented by and SiO 4 / 2 Organopolysiloxane copolymers containing siloxane units represented by R 1 2HSiO 1 / 2 The siloxane unit represented by and SiO 4 / 2 Organopolysiloxane copolymers containing siloxane units represented by R 1 HSiO 2 / 2 Siloxane units represented by and R 1 SiO 3 / 2 Siloxane units represented by HSiO 3 / 2 and mixtures of two or more of the above. 1 is a hydrocarbon group other than an alkenyl group, and specifically may be an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, or a heptyl group; an aryl group such as a phenyl group, a tolyl group, a xylyl group, or a naphthyl group; an aralkyl group such as a benzyl group or a phenethyl group; or a halogen-substituted alkyl group such as a chloromethyl group, a 3-chloropropyl group, or a 3,3,3-trifluoropropyl group.

[0097] The content of the (2) organopolysiloxane is not particularly limited as long as it is contained to an extent that allows appropriate curing. For example, the (2) organopolysiloxane may be contained in an amount such that the number of silicon-bonded hydrogen atoms is 0.5 to 10 per alkenyl group contained in the (1) organopolysiloxane. Within this range, curing can be sufficiently advanced to ensure heat resistance.

[0098] The addition curable silicone composition may further include platinum or a platinum compound as a catalyst for curing. The specific type of platinum or platinum compound is not particularly limited. The ratio of the catalyst may be adjusted to a level that allows suitable curing.

[0099] The addition-curable silicone composition may further contain appropriate additives in appropriate proportions required for improving storage stability, handling, and workability.

[0100] In another embodiment, the silicone composition is a condensation-curable silicone composition, and can include, for example, (a) an alkoxy-containing siloxane polymer; and (b) a hydroxyl-containing siloxane polymer.

[0101] The (a) siloxane polymer may be, for example, a compound represented by the following Chemical Formula 1.

[0102] [Chemical formula 1]

[0103] R 1 a R 2 b SiO c (OR 3 ) d

[0104] R in Chemical Formula 1 1 and R 2 each independently represents a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group; R 3 represents an alkyl group, R 1 , R 2 and R3 may be the same or different, when multiple occurrences of each are present, a and b each independently represent a number greater than or equal to 0 and less than 1, a+b represents a number greater than 0 and less than 2, c represents a number greater than 0 and less than 2, d represents a number greater than 0 and less than 4, and a+b+c×2+d is 4.

[0105] In the definition of Chemical Formula 1, the monovalent hydrocarbon may be, for example, an alkyl group having 1 to 8 carbon atoms, a phenyl group, a benzyl group, or a tolyl group, and in this case, the alkyl group having 1 to 8 carbon atoms may be, for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, or an octyl group. In addition, in the definition of Chemical Formula 1, the monovalent hydrocarbon group may be substituted with a known substituent such as, for example, a halogen, an amino group, a mercapto group, an isocyanate group, a glycidyl group, a glycidoxy group, or a ureido group.

[0106] In the definition of Chemical Formula 1, R 3 Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, and a butyl group. Among the alkyl groups, a methyl group or an ethyl group is usually used, but is not limited thereto.

[0107] A branched or tertiary crosslinked siloxane polymer can be used among the polymers of Chemical Formula 1. In addition, the (a) siloxane polymer may have residual hydroxyl groups within a range that does not impair the purpose, specifically, within a range that does not inhibit the dealcoholization reaction.

[0108] The (a) siloxane polymer can be produced, for example, by hydrolysis and condensation of a polyfunctional alkoxysilane or a polyfunctional chlorosilane. An average technician in this field can easily select a suitable polyfunctional alkoxysilane or chlorosilane for the desired (a) siloxane polymer, and can easily control the conditions of the hydrolysis and condensation reaction using the same. Meanwhile, when producing the (a) siloxane polymer, a suitable monofunctional alkoxysilane may be used in combination depending on the purpose.

[0109] As the (a) siloxane polymer, for example, commercially available organosiloxane polymers such as X40-9220 or X40-9225 from Shin-Etsu Silicones, and XR31-B1410, XR31-B0270 or XR31-B2733 from GE Toray Silicones can be used.

[0110] As the (b) hydroxyl group-containing siloxane polymer contained in the condensation-curable silicone composition, for example, a compound represented by the following chemical formula 2 can be used.

[0111] [Chemical formula 2]

[0112] [ka]

[0113] In formula 2, R 4 and R 5 each independently represents a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group; R 4 and R 5 When a plurality of each of is present, they may be the same or different, and n represents an integer of 5 to 2,000.

[0114] In the definition of Chemical Formula 2, specific examples of the monovalent hydrocarbon group include the same hydrocarbon groups as those in Chemical Formula 1 above.

[0115] Said (b) siloxane polymer can be produced, for example, by hydrolysis and condensation of dialkoxysilane and / or dichlorosilane. An average technician in this field can easily select a dialkoxysilane or dichlorosilane suitable for the desired (b) siloxane polymer, and can easily control the conditions of hydrolysis and condensation reaction using it. As said (b) siloxane polymer, for example, commercially available bifunctional organosiloxane polymers such as XC96-723, YF-3800, YF-3804, etc., from GE Toray Silicone Co., Ltd. can be used.

[0116] The above-mentioned addition curing or condensation curing silicone composition is one example of a material for forming a silicone pressure sensitive adhesive or adhesive that can be used in the present application. In other words, basically, all silicone pressure sensitive adhesives or adhesives known in the industry, such as OCA or OCR, can be used in the present application.

[0117] The type of the adhesive or the curable composition forming the adhesive is not particularly limited and may be appropriately selected according to the intended use. For example, a solid-phase, semi-solid-phase, or liquid-phase adhesive or the curable composition may be used. A solid-phase or semi-solid-phase adhesive or the curable composition may be cured before the objects to be bonded are attached. A liquid-phase adhesive or the curable composition is called an optically clear resin (OCR) and may be cured after the objects to be bonded are attached. According to one example, the adhesive or the curable composition may be a polydimethyl siloxane-based adhesive or the curable composition, a polymethylvinyl siloxane-based adhesive or the curable composition, or an alkoxy silicone-based adhesive or the curable composition, but is not limited thereto.

[0118] The thickness of the pressure sensitive adhesive layer or adhesive layer is not particularly limited and may be selected within an appropriate range to ensure the desired adhesive strength or cohesive strength. The thickness may be within the range of about 1 μm to 50 μm. In other examples, the thickness may be 2 μm or more, 3 μm or more, 4 μm or more, 5 μm or more, 6 μm or more, 7 μm or more, 8 μm or more, or 9 μm or more, or may be about 45 μm or less, 40 μm or less, 35 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, or 15 μm or less.

[0119] By including the adhesive layer or pressure sensitive adhesive layer in the above-mentioned arrangement, a roll-to-roll process is possible, and therefore, it is possible to provide an optical modulation device that has excellent processability, excellent adhesive strength, and excellent optical characteristics, particularly in blocking mode, by controlling light leakage.

[0120] In this way, by combining the alignment of the liquid crystal compound formed by a known vertical alignment film and an adhesive or pressure sensitive adhesive having vertical alignment ability with the above-mentioned retardation film and / or optically anisotropic layer, etc., it is possible to effectively suppress side light leakage in all directions when the liquid crystal compound is vertically aligned, and minimize absorption of front light when the liquid crystal compound is horizontally aligned.

[0121] For example, the present application may relate to a light modulation device in which a liquid crystal alignment film is formed on a first surface of a second substrate. The liquid crystal alignment film may be used to determine the initial alignment of the light modulation layer, and may be, for example, a vertical alignment film. In addition, the type of the liquid crystal alignment film is not particularly limited, and may be, for example, a known rubbing alignment film or photo-alignment film.

[0122] The alignment direction of the liquid crystal alignment layer may be the rubbing direction in the case of a rubbing alignment layer, or the direction of polarized light in the case of a photo-alignment layer, and such an alignment direction can be confirmed by a detection method using a linear polarizer. For example, when the light modulation layer is in a twisted alignment mode such as a reversed TN (Twisted Nematic) mode, if a linear polarizer is placed on one surface and the absorption axis of the polarizer is changed to measure the transmittance, the transmittance tends to be low when the absorption axis or transmission axis coincides with the alignment direction of the liquid crystal alignment layer, and the alignment direction can be confirmed through a simulation that reflects the refractive index anisotropy of the applied liquid crystal compound. A method for confirming the alignment direction of the liquid crystal alignment layer depending on the mode of the light modulation layer is known. In addition, the liquid crystal alignment layer may be a known rubbing alignment layer or a photo-alignment layer as described above, and the type of alignment layer that can be applied depending on the desired mode is known.

[0123] In the present application, the thickness of the liquid crystal alignment film may be, for example, within the range of 50 nm to 150 nm. In other examples, the thickness of the liquid crystal alignment film may be 60 nm or more, 70 nm or more, 80 nm or more, or 90 nm or more, or 140 nm or less, 130 nm or less, 120 nm or less, or 110 nm or less.

[0124] In one embodiment of the present application, when an adhesive layer or a pressure-sensitive adhesive layer having a vertical alignment force is formed on one side of the first substrate as described above, the first substrate does not need to have a liquid crystal alignment film formed thereon. This configuration allows the substrate to be applied to a roll-to-roll process, ensuring excellent processability.

[0125] In the present application, the gap between the first and second substrates arranged opposite to each other may be maintained by a spacer in the form of a partition wall. In one example, as shown in FIG. 1, the first polarizing layer 101 / the first substrate 201 / the optically anisotropic layer 700 / the adhesive layer or pressure-sensitive adhesive layer 400 / the light modulation layer 300 / the liquid crystal alignment film 500 / the second substrate 202 / the retardation film 600 / the second polarizing layer 102 may be formed in sequence, or as shown in FIG. 2, the first polarizing layer 101 / the retardation film 600 / the first substrate 201 / the optically anisotropic layer 700 / the adhesive layer or pressure-sensitive adhesive layer 400 / the light modulation layer 300 / the liquid crystal alignment film 500 / the second substrate 202 / the second polarizing layer 102 may be formed in sequence, and the gap G between the first and second substrates may be maintained by the spacer 800 in the form of a partition wall. In this case, the light modulation layer 300 may be present in an area where the spacer 800 does not exist, but is not limited thereto.

[0126] In the present application, the shape and arrangement of the spacer may be appropriately designed within a range that allows a constant distance to be maintained between the second substrate and the first substrate.

[0127] The spacer of the present application may be partitioned in the shape of a partition wall, or may be spaced apart in the shape of two or more columns, but is not limited thereto. In one example, the spacer may be rectangular, triangular, or honeycomb partition wall shape. In terms of effectively controlling light leakage in blocking mode, a rectangular partition wall shape is appropriate, and a square or rectangular partition wall shape may be appropriate, but is not limited thereto.

[0128] In the present application, the arrangement of the spacers, such as the pitch, line width, height, and area ratio on the top or second substrate, may be appropriately selected within a range that does not impair the object of the present application, where the area ratio refers to the percentage of the area where the spacers are formed relative to the total area of ​​the first surface of the second substrate.

[0129] In the present specification, the term "pitch" refers to the distance between opposing sides or between opposing vertices and sides when the spacer is observed from above. In the present specification, observing the spacer from above refers to observing the spacer parallel to the normal direction of the surface of the polymer film substrate formed with the spacer. In one example, when the spacer has a triangular partition shape, the term "pitch" may refer to the vertical distance between one vertex of the triangle and the side opposite the vertex. In another example, when the spacer has a rectangular partition shape, the term "pitch" may refer to the length of each side of the rectangle. When the lengths of the sides of the rectangle are all the same (i.e., when the rectangle is a square), the length of the same side is defined as the pitch, and when the lengths of the sides are not the same (e.g., when the rectangle is a rectangle), the arithmetic average of the lengths of all the sides may be defined as the pitch. In another example, when the spacer has a honeycomb (hexagonal) partition shape, the term pitch may refer to the distance between opposing sides of the hexagon, and when the distances between the opposing sides are all the same, the length of the distance between the same sides is defined as the pitch, and when the distances between the sides are not the same, the arithmetic average of the distances between all the sides may be defined as the pitch.

[0130] In the present application, the pitch of the spacers may be, for example, 50 μm to 500 μm, and in other examples, may be 100 μm or more, 150 μm or more, 200 μm or more, 250 μm or more, or 300 μm or more, or 450 μm or less, or 400 μm or less.

[0131] The term "line width" as used herein refers to a dimension of the spacer in a direction perpendicular to the length of the barrier rib when the spacer is observed from above. The line width of the spacer may be, for example, 1 μm to 50 μm, and may be 2 μm or more, 3 μm or more, 4 μm or more, 5 μm or more, 6 μm or more, 7 μm or more, 8 μm or more, or 9 μm or more, or 45 μm or less, 40 μm or less, 35 μm or less, 30 μm or less, 25 μm or less, 20 μm or less, 19 μm or less, 18 μm or less, 17 μm or less, 16 μm or less, 15 μm or less, 14 μm or less, 13 μm or less, 12 μm or less, or 11 μm or less.

[0132] In addition, the term "height of the spacer" generally corresponds to the thickness (cell gap) of the light modulating layer and refers to the dimension of the spacer measured in the normal direction of the surface of the polymer film substrate mentioned above. In the present application, the height of the spacer may be adjusted in consideration of the distance between the first substrate and the second substrate. For example, the height of the spacer may be 1 μm to 20 μm, and in other examples, 2 μm or more, 3 μm or more, 4 μm or more, or 5 μm or more, or 19 μm or less, 18 μm or less, 17 μm or less, 16 μm or less, 15 μm or less, 14 μm or less, 13 μm or less, 12 μm or less, 11 μm or less, 10 μm or less, 9 μm or less, 8 μm or less, or 7 μm or less. In one example, the height of the spacer may be approximately the same as the thickness of the light modulating layer.

[0133] In the present specification, the term area ratio means a value obtained by multiplying the ratio of the area (B) where the spacer is formed to the area (A) of the polymer film substrate, where A is the area of ​​the polymer film substrate, and the area where the spacer is formed, by 100, i.e., 100×B / A. In the present application, the area ratio of the spacer may be about 0.1% to 50% of the first or second polymer film substrate. In the present application, the larger the area ratio of the spacer, the greater the adhesive strength (or cohesive strength) of the first and second polymer film substrates. In other examples, it may be 1% or more, 2% or more, 3% or more, 4% or more, 5% or more, 6% or more, 7% or more, or 8% or more, or 45% or less, 40% or less, 35% or less, 30% or less, 25% or less, 20% or less, 15% or less, or 10% or less.

[0134] In the present application, the spacer may include, for example, a curable resin. The curable resin may be, for example, a heat-curable resin or a photo-curable resin, for example, an ultraviolet-curable resin, but is not limited thereto. The heat-curable resin may be, for example, a silicone resin, a silicon resin, a furan resin, a polyurethane resin, an epoxy resin, an amino resin, a phenol resin, an iodine resin, a polyester resin, or a melamine resin, but is not limited thereto. The ultraviolet-curable resin may be, for example, an acrylic polymer, for example, a polyester acrylate polymer, a polystyrene acrylate polymer, an epoxy acrylate polymer, a polyurethane acrylate polymer, a polybutadiene acrylate polymer, a silicone acrylate polymer, or an alkyl acrylate polymer, but is not limited thereto. In one example, the spacer may be formed using an acrylic polymer, more specifically, a polyester-based acrylate polymer, but is not limited thereto, and in another example, the spacer may be formed using a silicone polymer. When the spacer is formed using a silicone polymer, the silicone polymer remaining in the recessed area of ​​the spacer can function as a vertical alignment film, so that an additional liquid crystal alignment film does not need to be used on the substrate on which the spacer exists, as described above. As the silicone polymer, for example, a known polymer having a silicon-oxygen bond (Si-O-Si) as the main axis, such as polydimethylsiloxane (PDMS), can be used, but is not limited thereto.

[0135] By controlling the shape and / or arrangement of the spacer as described above, the present application can provide an optical modulation device in which the cell gap is properly maintained, the adhesion (or cohesiveness) between the upper and lower film substrates is excellent, and light leakage in blocking mode is properly controlled.

[0136] In addition to the above, the present inventors have confirmed that it is possible to effectively control omnidirectional light leakage in blocking mode by appropriately controlling the positional relationship between the axes of the polarizing layer, the polymer film, the retardation film and / or the liquid crystal alignment film. In this specification, the axis may refer to, for example, the absorption axis of the polarizing layer, the slow axis of the polymer film or the retardation film, or the alignment direction of the liquid crystal alignment film.

[0137] The first and second polarizing layers of the present application may, for example, be arranged with their absorption axes perpendicular to each other and / or the first and second polymeric films may, for example, be arranged with their slow axes horizontal to each other.

[0138] The absorption axis of the first and / or second polarizing layer and the slow axis of the first and / or second polymer film of the present application may also be arranged to be perpendicular or horizontal to each other. In one example, when the absorption axes of the first and second polarizing layers are arranged to be perpendicular to each other and the slow axes of the first and second polymer films are arranged to be horizontal to each other, the absorption axis of any one of the first and second polarizing layers and the slow axes of the first and second polymer films may be arranged to be perpendicular to each other, and the absorption axis of the other of the first and second polarizing layers and the slow axes of the first and second polymer films may be arranged to be horizontal to each other.

[0139] The light modulation device of the present application can effectively control light distortion phenomena such as rainbows by arranging a polarizing layer and / or a polymer film as described above and a retardation film, etc. as described below.

[0140] The retardation film of the present application may be arranged such that the slow axis of the retardation film is perpendicular to the slow axis of the first and / or second polymer film. In one example, when the slow axes of the first and / or second polymer film are arranged horizontally to each other, the slow axis of the retardation film may be arranged perpendicular to each of the slow axes of the first and second polymer films.

[0141] The retardation film of the present application may be arranged such that, for example, the slow axis of the retardation film is perpendicular to the absorption axis of the polarizing layer adjacent to the retardation film. In this specification, the meaning of the polarizing layer adjacent to the retardation film may be, for example, a polarizing layer formed directly in contact with the retardation film, or may mean a polarizing layer that is not formed directly in contact with the retardation film but is arranged closer to the retardation film among the first and second polarizing layers introduced into the structure of the light modulation device. In one example, in the case of a light modulation device having a structure as shown in FIG. 1, the polarizing layer adjacent to the retardation film may be the second polarizing layer. Therefore, in the case of a light modulation device as shown in FIG. 1, the slow axis of the retardation film may be arranged to be perpendicular to the absorption axis of the second polarizing layer. In another example, in the case of a light modulation device having a structure as shown in FIG. 2, the polarizing layer adjacent to the retardation film may be the first polarizing layer. Therefore, in the case of a light modulation device as shown in FIG. 2, the slow axis of the retardation film may be arranged to be perpendicular to the absorption axis of the first polarizing layer.

[0142] The liquid crystal alignment film of the present application may be arranged such that its alignment direction is horizontal or perpendicular to the slow axes of the first and / or second polymer films. The alignment direction of the liquid crystal alignment film may be, for example, the rubbing direction in the case of a rubbing alignment film, or the direction of polarized light in the case of a photo-alignment film. In one example, when the slow axes of the first and second polymer films are arranged to be horizontal to each other, the liquid crystal alignment film may be arranged such that its alignment direction is horizontal or perpendicular to each of the slow axes of the first and second polymer films. However, it may be more preferable in terms of optical properties that the liquid crystal alignment film is arranged such that its alignment direction is perpendicular to each of the slow axes of the first and second polymer films, while the slow axes of the first and second polymer films are arranged to be horizontal to each other, but is not limited thereto.

[0143] The light modulation device of the present application has a polarizing layer, a polymer film, a retardation film, an optically anisotropic layer, a light modulation layer and / or a liquid crystal alignment film, etc., having the above-mentioned characteristics, arranged at appropriate positions, and the relationship between the axes of each layer is controlled as described above, thereby enabling the device to have excellent transmittance variable characteristics while effectively controlling omnidirectional light leakage, especially in blocking mode.

[0144] In one example, the light modulation device of the present application may have a transmittance of 60% or less, 55% or less, 50% or less, 45% or less, 40% or less, 35% or less, 30% or less, 25% or less, 20% or less, 15% or less, 10% or less, 5% or less, 4% or less, 3% or less, 2% or less, 1% or less, 0.9% or less, 0.8% or less, 0.7% or less, 0.6% or less, 0.5% or less, 0.4% or less, or 0.3% or less when in the blocking mode. Since a lower transmittance is more advantageous in the blocking mode, the lower limit of the transmittance in the blocking mode state is not particularly limited, and in one example, the lower limit of the transmittance in the blocking mode state may be about 0%.

[0145] In one example, the light modulation device of the present application may have a transmittance of 20% or more in a transmission mode, and in another example, it may be about 21% or more, 22% or more, 23% or more, or 24% or more. The upper limit of the transmittance in the transmission mode state is not particularly limited, but in one example, the upper limit of the transmittance in the transmission mode state may be 60%, and in another example, it may be about 55% or less, 50% or less, 45% or less, 40% or less, 35% or less, or 30% or less.

[0146] In one example, the difference in transmittance between the transmission mode and the blocking mode of the optical modulation device of the present application may be 15% or more, 16% or more, 17% or more, 18% or more, 19% or more, 20% or more, 21% or more, 22% or more, 23% or more, or 24% or more, or may be 90% or less, 85% or less, 80% or less, 75% or less, 70% or less, 65% or less, 60% or less, 55% or less, 50% or less, 45% or less, 40% or less, 35% or less, 30% or less, or 25% or less.

[0147] The transmittance may be, for example, a rectilinear light transmittance. The rectilinear light transmittance may be a percentage of the ratio of light transmitted in the same direction as the incident direction to the light entering the light modulation device. For example, if the device is in the form of a film or sheet, the transmittance may be defined as the percentage of light transmitted through the device in a direction aligned with the normal direction of the film or sheet surface, among light incident in a direction aligned with the z-axis direction.

[0148] The transmittance may be a transmittance or reflectance for any one wavelength in the visible light region, for example, within a range of about 400 nm to 700 nm or about 380 nm to 780 nm, a transmittance or reflectance for the entire visible light region, a maximum or minimum transmittance or reflectance among the transmittances or reflectances for the entire visible light region, or an average value of the transmittances or average value of the reflectances in the visible light region. As another example, the transmittance may be a transmittance for light with a wavelength of about 550 nm.

[0149] In one example, the light modulation device of the present application may have a tilt angle transmittance of 3% or less when in blocking mode. In this specification, the tilt angle transmittance may mean a value measured by changing the radial angle Φ of the transmittance of light passing through the measurement object in a direction parallel to the axis direction at which the tilt angle from the z-axis direction, which is the normal direction of the reference surface of the measurement object (for example, the surface of the polarizing layer, polymer film, retardation film, optically anisotropic layer, or light modulation layer of the light modulation device), is Θ. In one example, it may mean a transmittance measured by changing the radial angle Φ in FIG. 3 to 0 degrees, 45 degrees, 90 degrees, 135 degrees, 180 degrees, 225 degrees, 270 degrees, and 315 degrees with respect to 60 degrees (tilt angle Θ in FIG. 3), with the z-axis direction, which is the normal direction of the reference surface of the measurement object, being 0 degrees. In the present application, the tilt angle transmittance in the blocking mode may be, in other examples, 2.9% or less, 2.8% or less, or 2.7% or less, or 0% or more, 0.5% or more, 1% or more, 1.5% or more, or 2% or more, but is not limited thereto.

[0150] The light modulation device of the present application may further include a conductive layer on one side of the first and second substrates, respectively. For example, a conductive layer may be formed between the adhesive layer or pressure-sensitive adhesive layer and the first substrate, and between the liquid crystal alignment film and the second substrate, respectively.

[0151] When a conductive layer is formed, the optically anisotropic layer may be disposed between the first substrate and the conductive layer, or between the conductive layer and a pressure-sensitive adhesive layer or adhesive layer, and / or between the second substrate and the conductive layer, or between the conductive layer and a liquid crystal alignment film.

[0152] The conductive layer can apply a suitable electric field to the light modulating layer to switch the alignment state of the liquid crystal compound in the light modulating layer. The direction of the electric field can be vertical or horizontal, for example, in the thickness direction or in the plane direction of the light modulating layer.

[0153] The conductive layer may be, for example, a transparent conductive layer, which may be formed by depositing, for example, a conductive polymer, a conductive metal, a conductive nanowire, or a metal oxide such as ITO (Indium Tin Oxide), etc. In addition, various materials and methods for forming a transparent conductive layer are known, and these may be used without limitation.

[0154] The light modulation device may be applied to various applications. Examples of applications to which the light modulation device may be applied include openings in enclosed spaces such as buildings, containers, and vehicles, such as windows and sunroofs, eyewear, fittings, and OLED (organic light emitting device) shading plates, etc. The scope of eyewear may include all eyewear formed to allow a viewer to view the outside through a lens, such as general glasses, sunglasses, sports goggles, helmets, and wearable devices such as virtual reality or augmented reality experience devices.

[0155] A typical application in which the light modulating device of the present application may be applied may be a sunroof for a vehicle.

[0156] In one example, the light modulation device may be a vehicle sunroof itself, for example, the light modulation device may be mounted in one or more openings in a vehicle body having the vehicle body and the vehicle sunroof may be mounted in the opening.

[0157] A sunroof is a fixed or movable (venting or sliding) opening in the roof of a vehicle, and may be a common name for a device that can function to allow light or fresh air to flow into the interior of the vehicle. In the present application, the operation method of the sunroof is not particularly limited, and for example, it can be operated manually or driven by a motor, and the shape, size, or style of the sunroof can be appropriately selected depending on the intended use. For example, the sunroof may be exemplified as a pop-up type sunroof, a spoiler (tile & slide) type sunroof, an in-built type sunroof, a folding type sunroof, a top-mounted type sunroof, a panoramic roof system type sunroof, a removable roof panel (T-tops or targa roofts) type sunroof, or a solar type sunroof, depending on the operation method, but is not limited thereto.

[0158] An exemplary sunroof of the present application may include the light modulating device of the present application, and in this case, the specific matters regarding the light modulating device may be the same as those described in the section on the light modulating device. Effect of the Invention

[0159] The present application relates to an optical modulation device that has excellent optical properties such as variable transmittance and mechanical properties, and controls light leakage in all directions in a blocking mode, and can be used for various purposes. [Brief description of the drawings]

[0160] [Figure 1]1 is a schematic diagram of an exemplary light modulating device of the present application. [Diagram 2] 1 is a schematic diagram of an exemplary light modulating device of the present application.

[0161] [Diagram 3] FIG. 2 is a schematic diagram for explaining an inclination angle and a radial vector angle.

[0162] [Figure 4] 1 is a diagram showing a method for evaluating refractive index anisotropy. [Explanation of symbols]

[0163] 101: First polarizing layer

[0164] 102: Second polarizing layer

[0165] 201: First substrate

[0166] 202: Second substrate

[0167] 400: Adhesive layer or pressure sensitive adhesive layer

[0168] 500: Liquid crystal alignment film

[0169] 300: Light modulation layer

[0170] 800: Spacer

[0171] 600: Phase contrast film

[0172] 700: Optically anisotropic layer

[0173] G: Cell gap DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0174] Hereinafter, the present application will be described in detail with reference to examples, but the scope of the present application is not limited to the following examples.

[0175] Evaluation example 1: Transmittance measurement in blocking mode

[0176] The transmittance in the blocking mode (no voltage applied, 0 V) ​​was measured using a haze meter (NDH5000SP, Secos) according to the ASTM D1003 standard.

[0177] Specifically, when light with a wavelength of 380 nm to 780 nm is incident on a measurement object inside an integrating sphere, the incident light is separated into diffused light (DT, the sum of all light diffused and emitted) and straight light (PT, light emitted in the front direction excluding diffused light) depending on the measurement object. The diffused light and straight light can be collected on a light receiving element inside the integrating sphere and measured separately. That is, through the above process, the total transmitted light (TT) can be defined as the sum (DT+PT) of the diffused light (DT) and straight light (PT). The total transmitted light means the total transmittance.

[0178] On the other hand, the maximum value of the tilt angle transmittance in the blocking mode (0V) for the optical modulation device was the largest value among the values ​​of the omnidirectional transmittance measured for a tilt angle of 60° with no voltage applied to the optical modulation device. The z-axis direction, which is the normal direction of the reference surface to be measured (for example, the reference surface can be the surface of the polarizing layer, polymer film, retardation film, optically anisotropic layer, or optical modulation layer of the optical modulation device) is set to 0°, and the largest value among the results measured while changing the radial angle Φ in FIG. 3 to 0°, 30°, 60°, 90°, 120°, 150°, 180°, 210°, 240°, 270°, 300°, and 330° with respect to 60° (tilt angle Θ in FIG. 3) is shown in Table 1.

[0179] Evaluation example 2. In-plane phase difference evaluation

[0180] The in-plane retardation (Rin) of polymer films, retardation films, etc. was measured using Agilent UV / VIS spectroscope 8453 equipment (550 nm wavelength standard). Two polarizers were installed in the UV / VIS spectroscope so that the transmission axes were perpendicular to each other, and the polymer film, retardation film, etc. was placed between the two polarizers so that the slow axis was at 45 degrees to the transmission axes of the two polarizers, and the transmittance was measured according to wavelength. The phase retardation order of each peak was calculated in the transmittance graph according to wavelength. Specifically, in the transmittance graph according to wavelength, the waveform satisfies the following formula A, and the maximum peak (Tmax) condition for a sine waveform satisfies the following formula B. When λmax is in formula A, T in formula A and T in formula B are the same, so the formula is expanded. The formula is expanded for n+1, n+2 and n+3, n and n+1 formulas are rearranged, R is eliminated, and n is rearranged with λn and λn+1 formulas, resulting in the following formula C. Since n and λ are known based on the fact that T in formula A and T in formula B are the same, R is found for each λn, λn+1, λn+2 and λn+3. A linear trend line of R value by wavelength is found for the four points, and the R value for light with a wavelength of 550 nm is calculated. The function of the linear trend line is Y=ax+b, where a and b are constants. The Y value when 550 nm is substituted for x in the above function is the Rin value for light with a wavelength of 550 nm.

[0181] [Formula A]

[0182] T = sin2[(2πR / λ)]

[0183] [Formula B]

[0184] T=sin2[((2n+1)π / 2)]

[0185] [Formula C]

[0186] n=(λn-3λn+1) / (2λn+1+1-2λn)

[0187] In the above, R means an in-plane retardation (Rin), λ means a wavelength, and n means the degree of the apex of the sine wave.

[0188] Evaluation example 3: Thickness of each layer

[0189] The thickness of the light modulation layer was equal to the height of the spacer, and the height of the spacer was measured using a measuring device (Optical profiler, Nano System, Nano View-E1000). The thickness of the optically anisotropic layer was also measured using the same measuring device (Optical profiler, Nano System, Nano View-E1000).

[0190] Meanwhile, the thicknesses of the polarizing layer, the retardation film and the adhesive layer (or pressure sensitive adhesive layer) were measured using a Digimatic thickness gauge (547, Kotoyosha).

[0191] Evaluation Example 4: Evaluation of refractive index anisotropy and average refractive index of light modulation layer (liquid crystal layer), retardation film or optically anisotropic layer

[0192] The refractive index anisotropy (△n) and average refractive index of the light modulation layer, retardation film, or optically anisotropic layer are evaluated using an Abbe refractometer in the following manner. A vertical alignment film is coated on the surfaces of the measuring prism and illumination prism of the Abbe refractometer, and the object to be measured is applied to the measuring prism and then covered with the illumination prism. The light modulation layer, retardation film, or optically anisotropic layer is vertically aligned due to the vertical alignment force of the two interfaces. In this process, the liquid crystal compound applied to the light modulation layer is only a liquid crystal compound that is not mixed with other substances such as dichroic dyes.

[0193] Then, as shown in Fig. 4, when a linear polarizer is applied to the eyepiece side (grounded part) and light is irradiated and observed, θe and θo as shown in Fig. 4 can be obtained, and the extraordinary refractive index (ne=npsinθe) and the ordinary refractive index (no=npsinθo) can be obtained from the refractive index (np) of the measuring prism and the angles (θe and θo). Here, the difference (ne-no) can be defined as the refractive index anisotropy, and the average value ((ne+no) / 2) can be defined as the average refractive index. The reference wavelength during the measurement is about 550 nm.

[0194] Example 1.

[0195] The device was fabricated using stretched PET (Polyethylene terephthalate) films (SKC Corporation) with thicknesses of 80 μm and 145 μm as the first and second substrates, respectively. The in-plane retardation of the first and second substrates for light with a wavelength of 550 nm was within the range of approximately 10,000 nm to 15,000 nm.

[0196] The first surface of the first substrate was bar-coated with a -C plate material, which was then cured at about 130°C for 20 minutes to form an optically anisotropic layer with a thickness of about 2 μm. An ITO (Indium Tin Oxide) film (conductive layer) was then deposited on the optically anisotropic layer. The optically anisotropic layer had a thickness direction retardation of about -220 nm for light with a wavelength of 550 nm, a refractive index anisotropy of about 0.1, and an average refractive index of 1.65. The -C plate material was prepared by mixing polyamide obtained by polymerizing terephthalic acid, isophthalic acid, and 2,2'-bis(trifluoromethyl)-4,4'-biphenyldiamine with a dimethylacetamide solution at about 5.3 wt %.

[0197] Next, a silicone adhesive (Shinetsu, KR3700) having vertical alignment power was bar-coated on the ITO film and cured at about 150° C. for 10 minutes to form an adhesive layer having a thickness of about 10 μm (first polymer film substrate).

[0198] First, an ITO (Indium Tin Oxide) film (conductive layer) was deposited on the first surface of the second substrate, and a spacer (pitch: 350 μm, height: 6 μm, line width: 10 μm, area ratio: 9%) in the form of a square partition wall was formed on the ITO film to maintain the cell gap. Then, to control the initial alignment of the light modulation layer (liquid crystal layer), a polyimide-based vertical alignment film (SE-5661LB3, Nissan) with a thickness of about 100 nm was formed on the first surface of the ITO film, and then rubbed with a rubbing cloth. At this time, the rubbing direction was perpendicular to the slow axes of the first and second substrates (second polymer film substrate).

[0199] Next, the adhesive layer of the first polymer film substrate and the vertical alignment film of the second polymer film substrate were arranged to face each other (cell gap: 6μm), and liquid crystal material was injected into the inside, and then a device was manufactured through a lamination process. As the liquid crystal material, a composition was used in which a liquid crystal compound (MAT-19-1261, Merck Co.) having a negative dielectric anisotropy with a refractive index anisotropy (Δn) of about 0.07 and an average refractive index of about 1.58 was mixed with a chiral dopant (S811, Merck Co.). At this time, the chiral dopant was mixed in an amount of about 0.58 parts by weight with respect to 100 parts by weight of the liquid crystal compound, so that the chiral pitch was about 20μm.

[0200] Next, a first polarizing layer was attached to the second surface of the first polymer film where no optically anisotropic layer was formed, and a retardation film was attached to the second surface of the second polymer film where no ITO film (conductive layer) was formed. In this case, an A-plate (LG CHEM) with an in-plane retardation of 275 nm for light with a wavelength of 550 nm and a thickness direction retardation of approximately 0 nm for light with a wavelength of 550 nm was used as the retardation film. The retardation film had a thickness of approximately 45 μm, a refractive index anisotropy of 0.7, and an average refractive index of 1.55.

[0201] Next, a second polarizing layer was formed on the second surface of the retardation film, which was the surface to which the second polymer film was not attached. The first and second polarizing layers were made of a general PVA polarizing layer, and each had a thickness of 140 μm.

[0202] In the above arrangement, the slow axes of the first and second substrates were horizontal to each other, the absorption axes of the first and second polarizing layers were perpendicular to each other, and the absorption axis of the first polarizing layer was horizontal to the slow axes of the first and second substrates. Also, the slow axis of the retardation film and the absorption axis of the second polarizing layer, which is the polarizing layer adjacent to the retardation film, were arranged perpendicular to each other.

[0203] As a result, a light modulation device was formed having a structure of first polarizing layer / first substrate / -C plate / ITO film / adhesive layer / light modulation layer (liquid crystal layer) / vertical alignment film / ITO film / second substrate / retardation film / second polarizing layer.

[0204] Example 2.

[0205] The device was fabricated using stretched PET (Polyethylene terephthalate) films (SKC Corporation) with thicknesses of 80 μm and 145 μm as the first and second substrates, respectively. The in-plane retardation of the first and second substrates for light with a wavelength of 550 nm was within the range of approximately 10,000 nm to 15,000 nm.

[0206] A retardation film was attached to one surface of the first substrate. An A-plate (LG Chem) with an in-plane retardation of 275 nm for light with a wavelength of 550 nm and a thickness direction retardation of approximately 0 nm for light with a wavelength of 550 nm was used as the retardation film. The retardation film had a thickness of approximately 45 μm, a refractive index anisotropy of 0.7, and an average refractive index of 1.55.

[0207] Next, a -C plate material was bar-coated on the first surface of the first substrate, which was the other surface to which the retardation film was not attached, and then cured at about 130°C for 20 minutes to form an optically anisotropic layer with a thickness of about 2 μm. Then, an ITO (Indium Tin Oxide) film (conductive layer) was vapor-deposited on the first surface of the optically anisotropic layer. The thickness direction retardation of the optically anisotropic layer for light with a wavelength of 550 nm was about -220 nm, the refractive index anisotropy was about 0.1, and the average refractive index was 1.65. Here, the -C plate material was prepared by mixing polyamide obtained by polymerizing terephthalic acid, isophthalic acid, and 2,2'-bis(trifluoromethyl)-4,4'-biphenyldiamine with a dimethylacetamide solution at about 5.3 wt %.

[0208] Next, a silicone adhesive (Shinetsu, KR3700) having vertical alignment power was bar-coated on the first surface of the ITO film and then cured at about 150°C for 10 minutes to form an adhesive layer having a thickness of about 10 μm (first polymer film substrate).

[0209] First, an ITO (Indium Tin Oxide) film (conductive layer) was deposited on the first surface of the second substrate, and a spacer (pitch: 350 μm, height: 6 μm, line width: 10 μm, area ratio: 9%) in the form of a square partition wall was formed on the ITO film to maintain the cell gap. Then, to control the initial alignment of the light modulation layer (liquid crystal layer), a polyimide-based vertical alignment film (SE-5661LB3, Nissan) with a thickness of about 100 nm was formed on the first surface of the ITO film, and then rubbed with a rubbing cloth. At this time, the rubbing direction was perpendicular to the slow axes of the first and second substrates (second polymer film substrate).

[0210] Next, the adhesive layer of the first polymer film substrate and the vertical alignment film of the second polymer film substrate were arranged to face each other (cell gap: 6μm), and liquid crystal material was injected into the inside, and then a device was manufactured through a lamination process. As the liquid crystal material, a composition was used in which a liquid crystal compound (MAT-19-1261, Merck Co.) having a negative dielectric anisotropy with a refractive index anisotropy (Δn) of about 0.07 and an average refractive index of about 1.58 was mixed with a chiral dopant (S811, Merck Co.). At this time, the chiral dopant was mixed in an amount of about 0.58 parts by weight with respect to 100 parts by weight of the liquid crystal compound, so that the chiral pitch was about 20μm.

[0211] Next, the retardation film was attached to the second surface of the first polymer film, which was the surface on which the optically anisotropic layer was not formed, and the first polarizing layer was attached to the second surface of the retardation film. The first and second polarizing layers were general PVA polarizing layers, each having a thickness of 140 μm.

[0212] In the above arrangement, the slow axes of the first and second substrates were horizontal to each other, the absorption axes of the first and second polarizing layers were perpendicular to each other, and the absorption axis of the first polarizing layer was perpendicular to the slow axes of the first and second polymer films. Also, the slow axis of the retardation film and the absorption axis of the first polarizing layer, which is the polarizing layer adjacent to the retardation film, were arranged perpendicular to each other.

[0213] As a result, a light modulation device was formed having a structure of first polarizing layer / retardation film / first substrate / -C plate / ITO film / adhesive layer / light modulation layer (liquid crystal layer) / vertical alignment film / ITO film / second substrate / second polarizing layer.

[0214] Comparative Example 1

[0215] The process was the same as in Example 1, except that no retardation film was attached to the second surface of the second substrate, which was the surface on which the ITO film (conductive layer) was not formed, and instead the second polarizing layer was directly attached to the second surface, thereby producing a light modulation device having a structure of first polarizing layer / first substrate / -C plate / ITO film / adhesive layer / light modulation layer (liquid crystal layer) / vertical alignment film / ITO film / second substrate / second polarizing layer.

[0216] [Table 1]

[0217] In Table 1, the inclination angle transmittance in blocking mode (0V) is the transmittance measured when no voltage is applied to the optical modulation device, with the z-axis direction, which is the normal direction of the reference surface to be measured (which may be, for example, the surface of the polarizing layer, polymer film, retardation film, optically anisotropic layer, or optical modulation layer of the optical modulation device), being set to 0 degrees, and the radial angle Φ in Figure 3 being changed to 0 degrees, 45 degrees, 90 degrees, 135 degrees, 180 degrees, 225 degrees, 270 degrees, and 315 degrees with respect to 60 degrees (the inclination angle Θ in Figure 3).

Claims

1. a first substrate and a second substrate each having a first surface and a second surface, the first surfaces of the first substrate and the second substrate being arranged so as to face each other; a light modulating layer between the first and second substrates; a polarizing layer formed on at least one of the second surface of the first substrate and the second surface of the second substrate; and a retardation film formed on the second surface of the first substrate or the second surface of the second substrate, between the polarizing layer and the first substrate or between the polarizing layer and the second substrate, having an in-plane retardation of 200 nm to 300 nm for light with a wavelength of 550 nm and a thickness of 20 μm to 70 μm; the first substrate and the second substrate are anisotropic substrates; At least one of the optical modulation layer and the first substrate or the optical modulation layer and the second substrate includes an optically anisotropic layer that satisfies the following formula 3 and has a refractive index anisotropy (Δn) in the range of 0.01 to 0.15: [Formula 3] nz < ny ≈ nx In Formula 3, nx is the refractive index of the optically anisotropic layer for light with a wavelength of 550 nm in the slow axis direction, ny is the refractive index of the optically anisotropic layer for light with a wavelength of 550 nm in the fast axis direction, and nz is the refractive index of the optically anisotropic layer in the thickness direction.

2. The retardation film satisfies the following formula 1 or 2: [Formula 1] nx>ny≒nz [Formula 2] nx≒nz>ny In Formula 1 and Formula 2, nx is the refractive index of the retardation film in the slow axis direction for light with a wavelength of 550 nm, ny is the refractive index of the retardation film in the fast axis direction for light with a wavelength of 550 nm, and nz is the refractive index in the thickness direction of the retardation film. The optical modulation device according to claim 1.

3. 3. The optical modulation device according to claim 1, wherein an adhesive layer or a pressure-sensitive adhesive layer is formed on the first surface of the first substrate, and a liquid crystal alignment film is formed on the first surface of the second substrate.

4. 4. The light modulating device of claim 3, wherein the adhesive or pressure sensitive adhesive layer is a silicone adhesive or pressure sensitive adhesive layer.

5. The optical modulation device according to claim 3 , wherein the first substrate does not have a liquid crystal alignment film formed thereon.

6. The light modulation device according to claim 3 , wherein the liquid crystal alignment film is a vertical alignment film.

7. 2. The optical modulation device of claim 1, wherein the polarizing layer includes a first polarizing layer formed on a surface of the first substrate and a second polarizing layer formed on a surface of the second substrate, and the absorption axes of the first polarizing layer and the second polarizing layer are perpendicular to each other.

8. 2. The light modulation device according to claim 1, wherein at least one of the polarizing layers is adjacent to the retardation film, and a slow axis of the retardation film and an absorption axis of the polarizing layer adjacent to the retardation film are perpendicular to each other.

9. 9. An optical modulation device according to claim 1, wherein the slow axes of the first and second substrates are parallel to each other.

10. 10. The light modulation device according to claim 1, wherein the slow axis of the retardation film and the slow axes of the first and second substrates are perpendicular to each other.

11. 4. The light modulation device according to claim 3, wherein the alignment direction of the liquid crystal alignment film is parallel or perpendicular to the slow axes of the first and second substrates.

12. 12. The optical modulation device according to claim 1, wherein the first substrate and the second substrate each have an in-plane retardation of 500 nm or more for light with a wavelength of 550 nm.

13. 13. The optical modulation device according to claim 1, wherein the distance between the first substrate and the second substrate is maintained by a partition-shaped spacer.

14. 14. A light modulating device according to any preceding claim, wherein the light modulating layer comprises a liquid crystal compound.

15. 15. A light modulating device according to claim 1, wherein the light modulating layer is configured to be switchable between a vertically aligned mode and a horizontally twisted mode.

16. 16. The light modulating device of claim 15, wherein the ratio d / p of the thickness d of the light modulating layer to the pitch p of the twisted mode is 1 or less.

17. A window comprising a light modulating device according to any one of claims 1 to 16.

18. A sunroof comprising a light modulating device according to any one of claims 1 to 16.

19. a first substrate and a second substrate each having a first surface and a second surface, the first surfaces of the first substrate and the second substrate being arranged so as to face each other; a light modulating layer present between the first substrate and the second substrate; and A retardation film is formed on the second surface of the first substrate or the second substrate, and has an in-plane retardation of 100 nm to 300 nm for light with a wavelength of 550 nm; the first substrate and the second substrate are anisotropic films; a slow axis of the retardation film and a slow axis of the first substrate and a slow axis of the second substrate are perpendicular to each other.

Images