Dimming device, imaging device, and near-eye display

Abstract

Provided is a dimming device having small azimuthal dependence of transmittance of light emitted in an oblique direction. The present invention includes a first liquid crystal optical element and a second liquid crystal optical element which each contain a liquid crystal material and a guest material and which can change the orientation direction of the guest material by application of a voltage. When the voltage is applied, an angle formed by the azimuth direction in which the guest material in the first liquid crystal optical element is inclined and the azimuth direction in which the guest material in the second liquid crystal optical element is inclined is 170-190°. Between the first liquid crystal optical element and the second liquid crystal optical element, at least two phase-retardation layers A and at least one phase-retardation layer C are included, in which at least a phase-retardation layer A, a phase-retardation layer C, and a phase-retardation layer A are arranged in the stated order. The phrase-retardation layers A satisfy nxA>nzA≥nyA, and the phase-retardation layer C satisfies nzC>nxC≥nyC.

Description

Light control device, imaging device, and near-eye display

[0001] The present invention relates to a dimming device, an imaging device, and a near-eye display.

[0002] In imaging devices such as cameras, a dimming device called a neutral-density filter is sometimes used to add effects to the captured image. This filter can uniformly reduce or change the amount of light regardless of wavelength. Neutral-density filters are also known as ND filters or light-reducing filters.

[0003] As a variable density ND filter, Patent Document 1 describes a variable transmission filter having two guest-host liquid crystal devices and a polarization state changing device, which is a half-wave plate, placed between them.

[0004] International Publication No. 2017 / 172277

[0005] According to our investigations, in a dimming device using two guest-host liquid crystal devices, we found that in a configuration where only a half-wave plate is placed between the two guest-host liquid crystal devices, the transmittance of light emitted in an oblique direction changes significantly depending on the azimuth angle.

[0006] The object of this invention is to provide a dimming device in which the transmittance of light emitted in an oblique direction has little dependence on the azimuth angle.

[0007] As a result of diligent research by the inventors into addressing the above problem, they found that the above problem can be solved by the following configuration.

[0008] [1] A dimming device comprising a first liquid crystal optical element and a second liquid crystal optical element, wherein the first liquid crystal optical element and the second liquid crystal optical element have a liquid crystal layer comprising a liquid crystal material and a guest material, the first liquid crystal optical element and the second liquid crystal optical element can change the orientation direction of the guest material by applying a voltage, the angle between the orientation direction in which the guest material in the first liquid crystal optical element tilts and the orientation direction in which the guest material in the second liquid crystal optical element tilts when a voltage is applied is 170° to 190°, and between the first liquid crystal optical element and the second liquid crystal optical element there are at least two phase difference layers A and at least one phase difference layer C, and the phase difference layers A and C and phase difference layers A are at least in this order, the phase difference layer A satisfies the following formula (1), and the phase difference layer C satisfies the following formula (2). Equation (1) nxA > nzA ≥ nyA nzC > nxC ≥ nyC Equation (2) Here, in Equation (1), nxA represents the refractive index of the phase difference layer A at a wavelength of 550 nm in the slow axis direction in the plane of the phase difference layer A, nyA represents the refractive index of the phase difference layer A in a direction perpendicular to the slow axis direction in the plane of the phase difference layer A, and nzA represents the refractive index of the phase difference layer A out of the plane. Also, in Equation (2), nxC represents the refractive index of the phase difference layer C at a wavelength of 550 nm in the slow axis direction in the plane of the phase difference layer C, nyC represents the refractive index of the phase difference layer C in a direction perpendicular to the slow axis direction in the plane of the phase difference layer C, and nzC represents the refractive index of the phase difference layer C out of the plane. [2] The dimming device according to [1], wherein at least one layer of the phase difference layer A is in contact with one of the first liquid crystal optical element and the second liquid crystal optical element. [3] A dimming device according to [1] or [2], having two or more phase difference layers A and two or more phase difference layers C. [4] A dimming device according to [3], having at least phase difference layers A and C in that order. [5] A dimming device according to [1] or [2], having four or more phase difference layers A and two or more phase difference layers C. [6] A dimming device according to [5], having at least phase difference layers A and C in that order. [7] A dimming device according to [1] or [2], having four or more phase difference layers A and four or more phase difference layers C.[8] The dimming device according to [7], having at least a phase difference layer A, a phase difference layer C, a phase difference layer A, a phase difference layer C, a phase difference layer A, a phase difference layer C, a phase difference layer A, and a phase difference layer C in this order. [9] The dimming device according to any one of [1] to [4], wherein the phase difference layer A satisfies the following formula (3) and the phase difference layer C satisfies the following formula (4): 225 nm < ReA < 325 nm Formula (3) -500 nm < RthC < -100 nm Formula (4) Here, in formula (3), ReA represents the in-plane retardation of the phase difference layer A at a wavelength of 550 nm. Also, in formula (4), RthC represents the thickness-direction retardation of the phase difference layer C at a wavelength of 550 nm.

[10] A dimming device according to any one of [1] to [8], wherein phase difference layer A satisfies the following formula (5) and phase difference layer C satisfies the following formula (6): 100 nm < ReA < 180 nm Formula (5) -250 nm < RthC < -50 nm Formula (6) Here, in formula (5), ReA represents the in-plane retardation of phase difference layer A at a wavelength of 550 nm. Also, in formula (6), RthC represents the thickness-direction retardation of phase difference layer C at a wavelength of 550 nm.

[11] A dimming device according to any one of [1] to [8], wherein there are two or more phase difference layers A, at least one of the phase difference layers A satisfies the following formula (7) and at least one other of the phase difference layers A satisfies the following formula (8). 17.5° < D(A) < 27.5° Equation (7) 62.5° < D(A) < 72.5° Equation (8) Here, D(A) represents the angle of the orientation of the slow axis of the phase difference layer A with respect to the orientation of the guest material in the first liquid crystal optical element when a voltage is applied.

[12] A dimming device according to any one of [1] to

[11] , wherein the guest material is a dichroic dye molecule.

[13] An imaging device including the dimming device according to any one of [1] to

[12] .

[14] A near-eye display including the dimming device according to any one of [1] to

[12] .

[0009] According to the present invention, it is possible to provide a dimming device in which the transmittance of light emitted in an oblique direction has little dependence on the azimuth angle.

[0010] Figure 1 is a conceptual diagram showing an example of the dimming device of the present invention. Figure 2 is a diagram illustrating the operation of the dimming device shown in Figure 1. Figure 3 is a diagram illustrating the operation of the dimming device shown in Figure 1. Figure 4 is a diagram illustrating the operation of the dimming device shown in Figure 1. Figure 5 is a conceptual diagram showing another example of the dimming device of the present invention. Figure 6 is a conceptual diagram showing another example of the dimming device of the present invention. Figure 7 is a conceptual diagram showing another example of the dimming device of the present invention. Figure 8 is a conceptual diagram showing an example of an imaging device having the dimming device of the present invention. Figure 9 is a contour plot showing the transmittance of light transmitted through the dimming device of the embodiment. Figure 10 is a contour plot showing the transmittance of light transmitted through the dimming device of the comparative example. Figure 11 is a conceptual diagram showing a conventional dimming device.

[0011] The present invention will be described in detail below.

[0012] The following description of the constituent elements may be based on typical embodiments of the present invention, but the present invention is not limited to such embodiments.

[0013] In this specification, a numerical range represented by "~" means a range that includes the numbers written before and after "~" as the lower and upper limits, respectively.

[0014] In this specification, terms such as “same” include a range of error that is generally accepted in the art, for example, a range of ±5%.

[0015] Furthermore, in this specification, parallel, orthogonal, and perpendicular do not mean parallel, orthogonal, and perpendicular in the strict sense, but rather a range of ±5° from parallel, orthogonal, or perpendicular, respectively. The same applies to other angles, which also refer to a range of ±5°.

[0016] In this specification, the "absorption axis" refers to the polarization direction in which the absorbance is maximized when linearly polarized light is incident on the element. The "transmission axis" refers to the direction perpendicular to the absorption axis in the element. Furthermore, the "latent axis" refers to the direction in which the refractive index is maximized in the element.

[0017] <Retardation> In this invention, Re(λ) and Rth(λ) represent the in-plane retardation and the retardation in the thickness direction (film thickness direction) at wavelength λ, respectively. Unless otherwise specified, wavelength λ is 550 nm.

[0018] In this invention, Re(λ) and Rth(λ) are values ​​measured at wavelength λ using an AxoScan OPMF-1 (manufactured by OptoScience Co., Ltd.). By inputting the average refractive index ((Nx + Ny + Nz) / 3) and film thickness (d (μm)) into the AxoScan, the following can be calculated in the slow phase axis direction (°): Re(λ) = R0(λ) Rth(λ) = ((Nx + Ny) / 2 - Nz) × d

[0019] Refractive Index In this invention, the refractive indices Nx, Ny, and Nz were measured using a multi-wavelength Abbe refractometer DR-M2 (manufactured by Atago Co., Ltd.) in combination with an interference filter (wavelength 546 nm).

[0020] Alternatively, values ​​from the Polymer Handbook (JOHN WILEY & SONS, INC.) and catalogs of various optical films can be used. Examples of average refractive index values ​​for major optical films are given below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), and polystyrene (1.59).

[0021] Embodiments of the present invention will be described below with reference to the drawings. The following figures are conceptual diagrams for illustrating the dimming device of the present invention. Therefore, the shape, size, thickness, and positional relationships of each component may not necessarily correspond to those of actual components.

[0022] [Dimming device] The dimming device of the present invention includes a first liquid crystal optical element and a second liquid crystal optical element, the first liquid crystal optical element and the second liquid crystal optical element each having a liquid crystal layer containing a liquid crystal material and a guest material, the first liquid crystal optical element and the second liquid crystal optical element can change the orientation direction of the guest material by applying a voltage, the angle between the azimuth angle direction in which the guest material in the first liquid crystal optical element tilts and the azimuth angle direction in which the guest material in the second liquid crystal optical element tilts when a voltage is applied is 170° to 190°, there are at least two phase difference layers A and at least one phase difference layer C between the first liquid crystal optical element and the second liquid crystal optical element, and there are at least two phase difference layers A and one phase difference layer C in this order, the phase difference layer A satisfies the following formula (1), and the phase difference layer C satisfies the following formula (2), the dimming device. nxA>nzA≧nyA Formula (1) nzC>nxC≧nyC Formula (2)

[0023] Here, in equation (1), nxA represents the refractive index at a wavelength of 550 nm in the direction of the slow axis within the plane of the phase difference layer A, nyA represents the refractive index in the direction perpendicular to the slow axis within the plane of the phase difference layer A, and nzA represents the refractive index out of the plane of the phase difference layer A.

[0024] Furthermore, in equation (2), nxC represents the refractive index at a wavelength of 550 nm in the direction of the slow axis within the plane of the phase difference layer C, nyC represents the refractive index in the direction perpendicular to the slow axis within the plane of the phase difference layer C, and nzC represents the refractive index out of the plane of the phase difference layer C.

[0025] Figure 1 is a conceptual diagram showing an example of the dimming device of the present invention. Figures 2 and 3 are diagrams illustrating the operation of the dimming device shown in Figure 1, respectively.

[0026] The dimming device 10a shown in Figure 1 comprises a first liquid crystal optical element 12, a phase difference layer A16a, a phase difference layer C18a, a phase difference layer A16b, and a second liquid crystal optical element 14, in this order. That is, the dimming device 10a has phase difference layers A16a, C18a, and A16b between the first liquid crystal optical element 12 and the second liquid crystal optical element 14. It is preferable that the phase difference layer A16a and the phase difference layer C18a, and the phase difference layer C18a and the phase difference layer A16b are in contact. In this invention, even if each layer is laminated with an adhesive layer in between, it is considered to be in contact.

[0027] <Liquid Crystal Optical Elements> The first liquid crystal optical element 12 and the second liquid crystal optical element 14 have a liquid crystal layer containing a liquid crystal material and a guest material, and the orientation direction of the guest material can be changed by applying a voltage. Hereinafter, when it is not necessary to distinguish between the first liquid crystal optical element 12 and the second liquid crystal optical element 14, they will simply be referred to as liquid crystal optical elements.

[0028] As shown in Figure 1, the liquid crystal optical element has a liquid crystal layer containing liquid crystal molecules 30 and dichroic dye molecules 32. The dichroic dye molecules 32 are guest materials in this invention. Although omitted in the example shown in Figure 1, the liquid crystal optical element has transparent electrode layers on both sides of the liquid crystal layer, and has a configuration that allows a voltage to be applied to the liquid crystal layer. The liquid crystal optical element may also have a support, an alignment film, a polarizing plate, etc. For example, the liquid crystal optical element is configured to have a support, a transparent electrode layer, an alignment film, a liquid crystal layer, an alignment film, a transparent electrode layer, and a support in this order.

[0029] In a liquid crystal optical element, the orientation direction of the liquid crystal molecules 30, which are the host material in the liquid crystal layer, changes when an applied voltage is applied, which in turn changes the orientation direction of the dichroic dye molecules 32, which are the guest material contained in the liquid crystal layer. As a result, the liquid crystal optical element continuously changes the light transmittance according to the orientation of the dichroic dye molecules 32.

[0030] For example, in a liquid crystal optical element, when no voltage is applied, the liquid crystal molecules 30 are oriented approximately perpendicular to the surface of the liquid crystal layer (the plane perpendicular to the stacking direction of each layer), as shown in Figure 1 (hereinafter simply referred to as "oriented perpendicularly"). When a certain voltage or higher (hereinafter referred to as the maximum voltage) is applied, the liquid crystal molecules 30 are oriented approximately parallel to the surface of the liquid crystal layer, as shown in Figure 2 (hereinafter simply referred to as "oriented horizontally"). When a voltage lower than the maximum voltage is applied, the liquid crystal molecules 30 are oriented at a predetermined angle relative to the surface of the liquid crystal layer, as shown in Figure 3, depending on the applied voltage.

[0031] In this process, the dichroic dye molecules 32 in the liquid crystal layer are oriented along the orientation direction of the liquid crystal molecules 30. As shown in Figures 1 to 3, the orientation state of the dichroic dye molecules 32 also changes in response to the applied voltage.

[0032] Therefore, as shown in Figure 1, when no voltage is applied, the dichroic dye molecules 32 are oriented vertically, resulting in high transmittance as they absorb little light incident from the surface of the liquid crystal layer. Also, as shown in Figure 2, when the maximum voltage is applied, the dichroic dye molecules 32 are oriented parallel to each other, so they absorb the linearly polarized component of the light incident from the surface of the liquid crystal layer in the direction in which the dichroic dye molecules 32 are oriented (hereinafter also referred to as the orientation direction), resulting in low transmittance. Furthermore, as shown in Figure 3, when a voltage lower than the maximum voltage is applied, the dichroic dye molecules 32 are oriented obliquely, so the transmittance is lower than when no voltage is applied and higher than when the maximum voltage is applied, allowing the transmittance to be adjusted according to the applied voltage.

[0033] In this invention, when a voltage is applied, the angle between the direction in which the guest material (dichroic dye molecule 32) in the first liquid crystal optical element 12 tilts and the direction in which the guest material (dichroic dye molecule 32) in the second liquid crystal optical element 14 tilts is 170° to 190°, preferably 175° to 185°, and more preferably 180°.

[0034] Specifically, as described above, when a voltage is applied to the liquid crystal layer of a liquid crystal optical element, the liquid crystal molecules 30 and dichroic dye molecules 32 in the liquid crystal layer change from a vertically oriented state (see Figure 1) to a state tilted relative to the surface of the liquid crystal layer (see Figure 3), and then to a parallel oriented state when the maximum voltage is applied (see Figure 2). At that time, the liquid crystal molecules 30 and dichroic dye molecules 32 in the liquid crystal layer of each liquid crystal optical element tilt in a predetermined direction due to the application of voltage. The first liquid crystal optical element 12 and the second liquid crystal optical element 14 are arranged such that the direction in which the liquid crystal molecules 30 and dichroic dye molecules 32 tilt due to the application of voltage (hereinafter also referred to as the orientation direction of the dichroic dye molecules 32) differs by 170° to 190°. In other words, as shown in Figure 3, when a voltage lower than the maximum voltage is applied, the orientation in which the liquid crystal molecules 30 and dichroic dye molecules 32 tilt differs by 170° to 190° between the first liquid crystal optical element 12 and the second liquid crystal optical element 14.

[0035] Furthermore, the liquid crystal layer of the liquid crystal optical element is not limited to one in which the liquid crystal molecules 30 and dichroic dye molecules 32 are oriented vertically when no voltage is applied. It may also be configured in which the liquid crystal molecules 30 and dichroic dye molecules 32 are oriented at an angle of less than 90° with respect to the surface (hereinafter also referred to as having a pre-tilt angle). In the case where the liquid crystal molecules 30 and dichroic dye molecules 32 have a pre-tilt angle, it can also be said that the orientation direction in which the liquid crystal molecules 30 and dichroic dye molecules 32 tilt due to having a pre-tilt angle differs by 170° to 190° between the first liquid crystal optical element 12 and the second liquid crystal optical element 14.

[0036] The first liquid crystal optical element 12 and the second liquid crystal optical element 14 each have a liquid crystal layer having liquid crystal molecules 30 (host material) and dichroic dye molecules 32 (guest material), and have a configuration that allows the orientation direction of the guest material to be changed by applying a voltage. They may have the same configuration or different configurations.

[0037] Further, the control of the applied voltage to the liquid crystal layer of the first liquid crystal optical element 12 and the control of the applied voltage to the liquid crystal layer of the second liquid crystal optical element 14 may be performed together or independently. That is, in the dimming device 10, the inclination angles of the liquid crystal molecules 30 and the dichroic dye molecules 32 with respect to the surface in the liquid crystal layer of the first liquid crystal optical element 12 and the inclination angles of the liquid crystal molecules 30 and the dichroic dye molecules 32 with respect to the surface in the liquid crystal layer of the second liquid crystal optical element 14 at a certain moment state may be the same or different.

[0038] As the liquid crystal optical element, a conventionally known dimming element having a liquid crystal layer having liquid crystal molecules and a guest material can be appropriately used. Further, as the liquid crystal composition containing liquid crystal molecules and a guest material, a known guest-host liquid crystal composition conventionally used for liquid crystal dimming elements can be used. As the combination of the guest material and the host material, any material in which the guest material is positive or negative and the host material is positive or negative can be used. Since the response characteristics by voltage application are good, the host material is preferably negative, for example, preferably a vertically aligned nematic guest-host liquid crystal.

[0039] <Retardation layer A> The retardation layers A16a and A16b are respectively disposed between the first liquid crystal optical element 12 and the second liquid crystal optical element 14 and satisfy the following formula (1). nx A> nz A ≧ ny A Formula (1) Here, in Formula (1), nx A represents the refractive index at a wavelength of 550 nm in the slow axis direction in the plane of the retardation layer A, ny A represents the refractive index in the direction orthogonal to the slow axis direction in the plane of the retardation layer A, and nz A represents the refractive index outside the plane of the retardation layer A.

[0040] That is, the retardation layers A16a and A16b are so-called positive A plates (optical members satisfying nx A> nz A ≒ ny A) or B plates satisfying nx A> nz A> ny A. In the following description, when there is no need to distinguish between the retardation layers A16a and A16b, they are also collectively referred to as the retardation layer A.

[0041] The in-plane retardation ReA of the phase difference layer A at 550 nm is appropriately set according to the number of layers arranged between the first liquid crystal optical element 12 and the second liquid crystal optical element 14, and is preferably a λ / 2 plate or a λ / 4 plate at a wavelength of 550 nm. For example, in the case of a configuration having two phase difference layers A between the first liquid crystal optical element 12 and the second liquid crystal optical element 14, as shown in the examples in Figures 1 to 3, it is preferable that the phase difference layer A16a and the phase difference layer A16b each satisfy the following equation (3). That is, the two phase difference layers A each act as approximately λ / 2 plates. 225 nm < ReA < 325 nm Equation (3) Here, in equation (3), ReA represents the in-plane retardation of the phase difference layer A at a wavelength of 550 nm. The in-plane retardation ReA of the phase difference layer A in the case of other layer configurations will be described later.

[0042] When there are two phase difference layers A, the in-plane retardation ReA of each phase difference layer A at a wavelength of 550 nm is more preferably 250 nm to 300 nm, even more preferably 265 nm to 285 nm, and particularly preferably 270 nm to 280 nm. Furthermore, when there are two phase difference layers A, the thickness-direction retardation RthA of each phase difference layer A at a wavelength of 550 nm is also preferably 100 nm to 170 nm, more preferably 120 nm to 150 nm, and even more preferably 130 nm to 140 nm.

[0043] Phase difference layers A16a and A16b are arranged such that the orientation of the in-plane slow axis is at a predetermined angle with respect to the orientation in which the guest material (dichroic dye molecule 32) in the first liquid crystal optical element 12 tilts when a voltage is applied. This angle is set appropriately according to the number of layers arranged between the first liquid crystal optical element 12 and the second liquid crystal optical element 14.

[0044] For example, as shown in the examples in Figures 1 to 3, if there are two phase difference layers A between the first liquid crystal optical element 12 and the second liquid crystal optical element 14, and each phase difference layer A acts as approximately λ / 2 plate, it is preferable that one phase difference layer A satisfies the following equation (7) and the other phase difference layer A satisfies the following equation (8). 17.5° < D(A) < 27.5° Equation (7) 62.5° < D(A) < 72.5° Equation (8) Here, D(A) represents the angle in the azimuthal direction of the lagging axis of the phase difference layer A with respect to the azimuthal angle direction in which the guest material in the first liquid crystal optical element tilts when a voltage is applied.

[0045] In other words, it is preferable that one of the two phase difference layers A is positioned with an in-plane slow axis angle D(A) of approximately 22.5°, and the other of the two phase difference layers A is positioned with an in-plane slow axis angle D(A) of approximately 67.5°.

[0046] The angle D(A) of one in-plane slow axis of phase difference layer A is more preferably 20° to 25°, and even more preferably 22.5°. The angle D(A) of the other in-plane slow axis of phase difference layer A is more preferably 65° to 70°, and even more preferably 67.5°. The angles of the in-plane slow axis of phase difference layer A in cases of other layer configurations will be described later.

[0047] There are no particular restrictions on the phase difference layer A; known A plates or B plates that satisfy the above formula can be used. From the viewpoint of ease of manufacture, the phase difference layer A16a is preferably a layer formed using a liquid crystal compound or a stretched polymer film (stretched film).

[0048] In the present invention, it is preferable that the phase difference layer A contains a liquid crystal compound. It is preferable that the phase difference layer A contains an optically anisotropic layer formed from a composition containing the liquid crystal compound, which includes a layer on which the liquid crystal compound is fixed. Since the liquid crystal molecules of the liquid crystal compound can be oriented to any direction using an alignment film or the like, the manufacturing process of the phase difference layer A can be simplified. In addition, the optically anisotropic layer can be made thinner more easily than a polymer film.

[0049] The phase difference layer A may contain one optical anisotropy layer or may contain multiple optical anisotropy layers. If it contains multiple optical anisotropy layers, the combination of the multiple optical anisotropy layers constitutes the phase difference layer. In other words, the phase difference performance of the phase difference layer A may be obtained by combining multiple optical anisotropy layers.

[0050] The type of liquid crystal compound used in the phase difference layer A is not particularly limited, but either rod-shaped (rod-shaped liquid crystal compound) or disc-shaped (discotic liquid crystal compound) liquid crystal compounds can be used. Two or more rod-shaped liquid crystal compounds, two or more disc-shaped liquid crystal compounds, or a mixture of rod-shaped and disc-shaped liquid crystal compounds may be used.

[0051] As rod-shaped liquid crystal compounds, for example, those described in claim 1 of Japanese Patent Publication No. 11-513019 and paragraphs

[0026] to

[0098] of Japanese Patent Application Publication No. 2005-289980 can be preferably used, and as disc-shaped liquid crystal compounds, for example, those described in paragraphs

[0020] to

[0067] of Japanese Patent Application Publication No. 2007-108732 and paragraphs

[0013] to

[0108] of Japanese Patent Application Publication No. 2010-244038 can be preferably used, but are not limited to these.

[0052] The liquid crystal compound contained in a composition containing a liquid crystal compound preferably has a polymerizable group. Therefore, the phase difference layer preferably contains a liquid crystal compound oriented by polymerization. As the polymerizable group, a polymerizable group capable of radical polymerization or cationic polymerization is preferred. As the radical polymerizable group, generally known radical polymerizable groups can be used, and preferred examples include the acryloyloxy group or the methacryloyloxy group. In this case, the polymerization rate of the acryloyloxy group is generally known to be faster, and the acryloyloxy group is preferred in terms of improving productivity, but the methacryloyloxy group can also be used similarly as a polymerizable group. As the cationic polymerizable group, generally known cationic polymerizable groups can be used, and specifically, examples include alicyclic ether groups, cyclic acetal groups, cyclic lactone groups, cyclic thioether groups, spiroorthoester groups, and vinyloxy groups. Among these, alicyclic ether groups or vinyloxy groups are preferred, and epoxy groups, oxetanyl groups, or vinyloxy groups are particularly preferred.

[0053] Furthermore, it is preferable that the phase difference layer A has inverse wavelength dispersion. Inverse wavelength dispersion refers to the property that when the in-plane retardation (Re) value at a specific wavelength (visible light range) is measured, the Re value increases as the measured wavelength increases. It is preferable that Re(450) / Re(550) < 1.00 and Re(650) / Re(550) > 1.00 are satisfied.

[0054] Furthermore, when forming a phase difference layer A having inverse wavelength dispersion, it is preferable to use a liquid crystal compound that has a maximum absorption in the wavelength range of 300 nm to 400 nm and has polymerizable groups. The liquid crystal compound is not particularly limited as long as the above requirements are satisfied, and known liquid crystal compounds can be used. Note that the composition containing the liquid crystal compound may contain multiple types of liquid crystal compounds, and it is sufficient if one or more of the liquid crystal compounds satisfy the above requirements. Note that having a maximum absorption in the wavelength range of 300 nm to 400 nm means that in the ultraviolet-visible light absorption spectrum in the wavelength range of 200 nm to 800 nm, measured by a spectrophotometer using a solution in which the liquid crystal compound is dissolved, there is a maximum value in the wavelength range of 300 nm to 400 nm. When a liquid crystal compound exhibits inverse wavelength dispersion, it often has a maximum absorption in the wavelength range of 300 nm to 400 nm.

[0055] A phase difference layer A having inverse wavelength dispersion can be produced, for example, by uniaxially stretching a polymer film such as a modified polycarbonate resin film having inverse wavelength dispersion, referring to Japanese Patent Application Publication No. 2017-049574. Alternatively, a phase difference layer A having inverse wavelength dispersion can also be produced by oriented and immobilizing a rod-shaped liquid crystal compound having inverse wavelength dispersion, referring to Japanese Patent Application Publication No. 2020-084070.

[0056] The composition containing the liquid crystal compound for forming the phase difference layer A (optical anisotropy layer) can be a conventionally known composition used for forming coating films, and may contain components other than the liquid crystal compound mentioned above. For example, the composition may contain polymerization initiators, surfactants, solvents, orientation agents, adhesion improvers, plasticizers, polymers, and the like.

[0057] <<Method for Forming Phase Difference Layer A>> The method for forming the phase difference layer A (optical anisotropy layer) is not particularly limited and known methods can be used. For example, an optical anisotropy layer can be produced by applying an optical anisotropy layer-forming composition containing a liquid crystal compound to a predetermined support (including a temporary substrate) to form a coating film, and then subjecting the obtained coating film to a curing treatment (irradiation with ultraviolet light (light irradiation treatment) or heat treatment) to fix the liquid crystal compound. If necessary, an alignment layer described later may also be used.

[0058] The above composition can be applied by known methods (for example, wire bar coating, extrusion coating, direct gravure coating, reverse gravure coating, or die coating).

[0059] Furthermore, before curing the formed coating film, an orientation treatment may be performed to orient the liquid crystal compounds in the coating film. The orientation treatment can be performed by drying the coating film at room temperature or by heating the coating film. There are no particular restrictions on the conditions for heating the coating film, but the heating temperature is preferably 50 to 250°C, more preferably 50 to 150°C, and the heating time is preferably 10 seconds to 10 minutes. After heating the coating film, the coating film may be cooled as needed before the curing treatment (light irradiation treatment). The cooling temperature is preferably 20 to 200°C, more preferably 30 to 150°C.

[0060] The curing treatment method applied to the coating film on which the liquid crystal compound is oriented is not particularly limited, and examples include light irradiation and heat treatment. Among these, light irradiation is preferred from the viewpoint of manufacturability, and ultraviolet irradiation is more preferred. The irradiation conditions for light irradiation are not particularly limited, but 50 to 1000 mJ / cm² is preferred. ２ The irradiation dose is preferred. The atmosphere during the light irradiation treatment is not particularly limited, but a nitrogen atmosphere is preferred.

[0061] -Support- The support supports the optical anisotropy layer and the alignment film described later. Various sheet-like materials (films, plates) can be used as the support, as long as they can support the alignment film and the optical anisotropy layer. To form a uniform optical anisotropy layer over a large area, a film-like, sheet-like, or flat plate-like support is preferred. For industrial continuous production, a long film-like (sheet-like) support can also be used.

[0062] As the support, a transparent support is preferred, and examples include glass substrates and polymer films. Examples of polymer film materials include cellulose polymers; acrylic polymers having acrylic acid ester polymers such as polymethyl methacrylate and lactone ring-containing polymers; thermoplastic norbornene polymers; polycarbonate polymers; polyester polymers such as polyethylene terephthalate and polyethylene naphthalate; styrene polymers such as polystyrene and acrylonitrile-styrene copolymer (AS resin); polyolefin polymers such as polyethylene, polypropylene, and ethylene-propylene copolymer; vinyl chloride polymers; amide polymers such as nylon and aromatic polyamides; imide polymers; sulfone polymers; polyethersulfone polymers; polyetheretherketone polymers; polyphenylene sulfide polymers; vinylidene chloride polymers; vinyl alcohol polymers; vinyl butyral polymers; arylate polymers; polyoxymethylene polymers; epoxy polymers; or polymers obtained by mixing these polymers. The support is not limited to a flexible film, but may also be a non-flexible substrate such as a glass substrate. Furthermore, the support may be multilayered, and examples of multilayered supports include those that include one of the above-mentioned supports as a substrate, with other layers provided on the surface of this substrate.

[0063] There are no restrictions on the thickness of the support; it can be set appropriately depending on the support material, etc., as long as sufficient self-supporting and strength to withstand the process of forming the optical anisotropy layer is ensured. The thickness of the support is preferably 5 to 200 μm, more preferably 10 to 100 μm, and even more preferably 20 to 90 μm. Furthermore, the support may be one that can be peeled off as needed after the optical anisotropy layer has been formed.

[0064] - Alignment Film - Due to the need to efficiently control the orientation of liquid crystal compounds in a composition to a desired state, it is common practice to impart an orientation-regulating force to the surface of the support. Known methods for imparting an orientation-regulating force include providing an alignment film and further processing as needed, and directly processing the surface of the support.

[0065] Methods for providing an alignment film and further processing as needed include, for example, coating a thin resin layer and applying a rubbing treatment to its surface (rubbing method), and coating a material that exhibits orientation restricting force in a specific direction when polarized light is irradiated, and then irradiating it with polarized light in the desired direction (photo-alignment method). In particular, the photo-alignment method has been favored in recent years because it can impart orientation restricting force in any direction simply by controlling the polarization axis of the irradiated linearly polarized light. Materials for the alignment film (photo-alignment film) that can be used in such photo-alignment methods include polymer materials such as photo-aligning polymers having a cinnamoyl structure, polyamide compounds, and polyimide compounds; liquid crystal alignment films formed by liquid crystal alignment agents having photo-aligning groups as described in Japanese Patent Application Publication No. 2012-155308; and products such as LPP-JP265CP manufactured by Rolic Technologies.

[0066] The thickness of the alignment film is not particularly limited, but for example, 0.01 to 10 μm is preferred, 0.01 to 1 μm is more preferred, and 0.01 to 0.5 μm is even more preferred. Furthermore, the alignment film may be one that can be peeled off as needed after the optical anisotropy layer is formed.

[0067] <Phase Difference Layer C> The phase difference layer C18a is positioned between the first liquid crystal optical element 12 and the second liquid crystal optical element 14, and satisfies the following equation (2): nzC > nxC ≥ nyC Equation (2) Here, in equation (2), nxC represents the refractive index of the phase difference layer C18a at a wavelength of 550 nm in the direction of the slow phase axis within the plane, nyC represents the refractive index of the phase difference layer C18a in a direction perpendicular to the slow phase axis within the plane, and nzC represents the refractive index of the phase difference layer C18a out of the plane.

[0068] In other words, the phase difference layer C18a is a so-called positive C plate (an optical element satisfying nzC > nxC ≈ nyC) or a B plate satisfying nzC > nxC > nyC.

[0069] The thickness direction retardation RthC of the phase difference layer C at 550 nm is set appropriately according to the number of layers arranged between the first liquid crystal optical element 12 and the second liquid crystal optical element 14. For example, as shown in Figures 1 to 3, in a configuration where there are two λ / 2 layers of phase difference layer A16a and one layer of phase difference layer C18a between the first liquid crystal optical element 12 and the second liquid crystal optical element 14, it is preferable that the thickness direction retardation RthC of the phase difference layer C18a at 550 nm satisfies the following equation (4): -500 nm < RthC < -100 nm Equation (4) Here, in equation (4), RthC represents the thickness direction retardation of the phase difference layer C at a wavelength of 550 nm. The thickness direction retardation RthC of the phase difference layer C in the case of other layer configurations will be described later.

[0070] Furthermore, the retardation RthC in the thickness direction of the phase difference layer C at a wavelength of 550 nm is more preferably -300 nm to -120 nm, and even more preferably -200 nm to -150 nm. Also, the in-plane retardation ReC of the phase difference layer C at a wavelength of 550 nm is also preferably -20 nm to 20 nm, more preferably -10 nm to 10 nm, and even more preferably -10 nm to 0 nm.

[0071] There are no particular restrictions on the phase difference layer C; known C plates or B plates that satisfy the above formula can be used. From the viewpoint of ease of manufacture, the phase difference layer C18a is preferably a layer formed using a liquid crystal compound (optical anisotropy layer) or a stretched polymer film (stretched film).

[0072] The liquid crystal compound used to form the phase difference layer C can be the same liquid crystal compound used to form the phase difference layer A described above. Furthermore, the composition containing the liquid crystal compound used to form the phase difference layer C (optical anisotropy layer) can be a conventionally known composition used for forming coating films, and may contain components other than the liquid crystal compound. For example, the composition may contain polymerization initiators, surfactants, solvents, orientation agents, adhesion improvers, plasticizers, polymers, and the like.

[0073] Furthermore, the phase difference layer C (optical anisotropy layer) can be formed using the same method as the formation method for the phase difference layer A (optical anisotropy layer) described above, except that the orientation state of the liquid crystal compound is different. For example, when a rod-shaped liquid crystal compound is used as the liquid crystal compound, the phase difference layer C (optical anisotropy layer) can be formed by orienting the rod-shaped liquid crystal compound perpendicular to the surface of the coating film (optical anisotropy layer) and curing it. For example, the liquid crystal compound can be made to be perpendicularly oriented by including a vertical alignment agent in the composition.

[0074] <Operation of the dimming device> Next, the operation of the dimming device of the present invention will be explained using Figures 1 to 4.

[0075] First, we will explain the effect of light incident on the surface of the dimming device 10a (first liquid crystal optical element 12) from a direction perpendicular to it.

[0076] When no voltage is applied to the first liquid crystal optical element 12 and the second liquid crystal optical element 14, unpolarized light incident from the first liquid crystal optical element 12 is transmitted through the first liquid crystal optical element 12 without being absorbed by it, remaining unpolarized. This unpolarized light then passes through the phase difference layer A16a, phase difference layer C18a, and phase difference layer A16b without being absorbed by the second liquid crystal optical element 14, remaining unpolarized. Therefore, the dimming device 10a transmits light with very high transmittance.

[0077] Next, as shown in Figure 2, when the maximum voltage is applied to the first liquid crystal optical element 12 and the second liquid crystal optical element 14, as shown in Figure 4, the first liquid crystal optical element 12 absorbs the linearly polarized component in a predetermined direction from the unpolarized light incident from the first liquid crystal optical element 12 side. As a result, the light that passes through the first liquid crystal optical element 12 becomes linearly polarized X1 with a predetermined polarization direction and is incident on the phase difference layer A16a, phase difference layer 18a, and phase difference layer A16b in that order. Phase difference layer A16a has an in-plane retardation of approximately λ / 2 and the angle of the in-plane slow axis is approximately 67.5°, and phase difference layer A16b also has an in-plane retardation of approximately λ / 2 and the angle of the in-plane slow axis is approximately 22.5°. Therefore, when linearly polarized X1 is incident on phase difference layer A16a, its polarization direction is rotated by approximately 90° to become linearly polarized X2. In this case, the phase difference layer C18a does not have any optical effect on light incident perpendicular to the surface. Since the orientation direction of the dichroic dye molecules 32 of the second liquid crystal optical element 14 is approximately 180° different from the orientation direction of the dichroic dye molecules 32 of the first liquid crystal optical element 12, linearly polarized light X2 is absorbed by the second liquid crystal optical element 14. Consequently, the transmittance of the dimming device 10a becomes very low.

[0078] Next, when a voltage lower than the maximum voltage is applied to the first liquid crystal optical element 12 and the second liquid crystal optical element 14, the unpolarized light incident from the first liquid crystal optical element 12 absorbs a portion of the linearly polarized component in a predetermined direction. As a result, the light that passes through the first liquid crystal optical element 12 has more linearly polarized components approximately parallel to the linearly polarized X1 than linearly polarized components perpendicular to it (components parallel to X2), and is incident on the phase difference layer A16a, phase difference layer 18a, and phase difference layer A16b in that order. Phase difference layers A16a and A16b rotate this light by approximately 90°, converting it into light in which the linearly polarized component approximately parallel to the linearly polarized X2 is greater than the linearly polarized component perpendicular to it (components parallel to X1). This light is incident on the second liquid crystal optical element 14, where a portion of the linearly polarized component approximately parallel to X2 is absorbed, and the remaining portion of the linearly polarized component approximately parallel to X2 and the linearly polarized component approximately perpendicular to X2 are transmitted. Therefore, the transmittance of the dimming device 10a is lower than when no voltage is applied and higher than when the maximum voltage is applied, and the transmittance can be adjusted by the applied voltage.

[0079] In the case of a conventional dimming device 110, where only a phase difference layer A116, which is a λ / 2 plate, is located between the first liquid crystal optical element 112 and the second liquid crystal optical element 114 (see Figure 11), the phase difference imparted by the phase difference layer A116 to light incident on the surface of the dimming device 110 (first liquid crystal optical element 112) from an oblique direction deviates from λ / 2, and the amount of this deviation differs depending on the azimuth of the incident light. That is, even if the angle of incident light with respect to the perpendicular to the surface of the dimming device 110 (first liquid crystal optical element 112) is constant, the phase difference imparted by the phase difference layer A116 to the light will differ depending on the azimuth of the incident light. As a result, the polarization state of the light incident on the second liquid crystal optical element 114 will differ depending on the azimuth of the incident light, and the amount of light absorbed by the second liquid crystal optical element 114 will also differ, resulting in different transmittances depending on the azimuth of the incident light.

[0080] In contrast, the dimming device 10a of the present invention has at least two phase difference layers A and at least one phase difference layer C18a between the first liquid crystal optical element 12 and the second liquid crystal optical element 14.

[0081] The dimming device 10a of the present invention has a phase difference layer C18a in addition to the two phase difference layers A16a and A16b between the first liquid crystal optical element 12 and the second liquid crystal optical element 14. This allows for optical compensation for light incident from an oblique direction, providing a similar phase difference for incident light at any azimuth angle as long as the polar angle is constant. This reduces the difference in the amount of light absorbed by the second liquid crystal optical element 114, thereby reducing the change in transmittance due to the azimuth angle of the incident light, i.e., the azimuth angle dependence of the transmittance.

[0082] In the examples shown in Figures 1 to 3, the dimming device 10a has a configuration in which two phase difference layers A and one phase difference layer C are located between the first liquid crystal optical element 12 and the second liquid crystal optical element 14, but it is not limited to this configuration.

[0083] For example, the dimming device of the present invention may have two or more phase difference layers A and two or more phase difference layers C between the first liquid crystal optical element 12 and the second liquid crystal optical element 14.

[0084] For example, the dimming device 10c shown in Figure 5 has, between the first liquid crystal optical element 12 and the second liquid crystal optical element 14, a phase difference layer A16a, a phase difference layer C18a, a phase difference layer A16b, and a phase difference layer C18b, in that order from the side of the first liquid crystal optical element 12.

[0085] In the case of a dimming device 10c shown in Figure 5, which has two phase difference layers A, it is preferable that each phase difference layer A satisfies the following equation (3) and each phase difference layer C satisfies the following equation (4). That is, the two phase difference layers A each act as approximately λ / 2 plates. 225 nm < ReA < 325 nm Equation (3) -500 nm < RthC < -100 nm Equation (4) Here, in equation (3), ReA represents the in-plane retardation of phase difference layer A at a wavelength of 550 nm. Also, in equation (4), RthC represents the thickness-direction retardation of phase difference layer C at a wavelength of 550 nm.

[0086] When there are two phase difference layers A, the in-plane retardation ReA of each phase difference layer A at a wavelength of 550 nm is more preferably 250 nm to 300 nm, even more preferably 265 nm to 285 nm, and particularly preferably 270 nm to 280 nm. Furthermore, when there are two phase difference layers A, the thickness-direction retardation RthA of each phase difference layer A at a wavelength of 550 nm is also preferably 100 nm to 170 nm, more preferably 120 nm to 150 nm, and even more preferably 130 nm to 140 nm.

[0087] Furthermore, the retardation RthC in the thickness direction of the phase difference layer C at a wavelength of 550 nm is more preferably -300 nm to -120 nm, and even more preferably -200 nm to -150 nm. Also, the in-plane retardation ReC of the phase difference layer C at a wavelength of 550 nm is also preferably -20 nm to 20 nm, more preferably -10 nm to 10 nm, and even more preferably -10 nm to 0 nm.

[0088] Furthermore, if there are two phase difference layers A, and each phase difference layer A acts as approximately λ / 2 plate, it is preferable that one phase difference layer A satisfies equation (7) below, and the other phase difference layer A satisfies equation (8) below. 17.5° < D(A) < 27.5° Equation (7) 62.5° < D(A) < 72.5° Equation (8) Here, D(A) represents the angle in the azimuthal direction of the lagging axis of the phase difference layer A with respect to the azimuthal angle direction in which the guest material in the first liquid crystal optical element tilts when a voltage is applied.

[0089] In other words, it is preferable that one of the two phase difference layers A is positioned with an in-plane slow axis angle D(A) of approximately 22.5°, and the other of the two phase difference layers A is positioned with an in-plane slow axis angle D(A) of approximately 67.5°.

[0090] The angle D(A) of one in-plane slow axis of phase difference layer A is more preferably 20° to 25°, and even more preferably 22.5°. The angle D(A) of the other in-plane slow axis of phase difference layer A is more preferably 65° to 70°, and even more preferably 67.5°.

[0091] Thus, by having two phase difference layers A and two phase difference layers C, and by setting the orientation angles of the in-plane slow phase axes of the two phase difference layers A as described above, optical compensation for light incident from an oblique direction can be made more precise, and the azimuthal dependence of transmittance can be made smaller.

[0092] Furthermore, for example, the dimming device of the present invention may have four or more phase difference layers A and two or more phase difference layers C between the first liquid crystal optical element 12 and the second liquid crystal optical element 14.

[0093] For example, the dimming device 10d shown in Figure 6 has, between the first liquid crystal optical element 12 and the second liquid crystal optical element 14, a phase difference layer A16a, a phase difference layer C18a, a phase difference layer A16b, a phase difference layer A16c, a phase difference layer C18b, and a phase difference layer A16d, in this order from the first liquid crystal optical element 12 side.

[0094] Alternatively, for example, the dimming device of the present invention may have four or more phase difference layers A and four or more phase difference layers C between the first liquid crystal optical element 12 and the second liquid crystal optical element 14.

[0095] For example, the dimming device 10e shown in Figure 7 has, between the first liquid crystal optical element 12 and the second liquid crystal optical element 14, a phase difference layer A16a, a phase difference layer C18a, a phase difference layer A16b, a phase difference layer C18b, a phase difference layer A16c, a phase difference layer C18c, a phase difference layer A16d, and a phase difference layer C18d, in this order from the first liquid crystal optical element 12 side.

[0096] In the case of a dimming device 10d shown in Figure 6, or a dimming device 10e shown in Figure 7, which has four phase difference layers A, it is preferable that phase difference layer A satisfies the following equation (5) and phase difference layer C satisfies the following equation (6). That is, each of the four phase difference layers A acts as approximately λ / 4 plates. 100 nm < ReA < 180 nm Equation (5) -250 nm < RthC < -50 nm Equation (6) Here, in equation (5), ReA represents the in-plane retardation of phase difference layer A at a wavelength of 550 nm. Also, in equation (6), RthC represents the thickness-direction retardation of phase difference layer C at a wavelength of 550 nm.

[0097] When there are four phase difference layers A, the in-plane retardation ReA of each phase difference layer A at a wavelength of 550 nm is more preferably 112 nm to 162 nm, and even more preferably 122 nm to 152 nm. When there are four phase difference layers A, the thickness-direction retardation RthA of each phase difference layer A at a wavelength of 550 nm is also preferably 50 nm to 90 nm, and more preferably 60 nm to 80 nm.

[0098] Furthermore, the retardation RthC in the thickness direction of the phase difference layer C at a wavelength of 550 nm is more preferably -150 nm to -60 nm, even more preferably -140 nm to -70 nm, and particularly preferably -120 nm to -90 nm. Also, the in-plane retardation ReC of the phase difference layer C at a wavelength of 550 nm is also preferably -20 nm to 20 nm, more preferably -10 nm to 10 nm, and even more preferably -10 nm to 0 nm.

[0099] Furthermore, if there are four phase difference layers A, and each phase difference layer A acts as approximately λ / 4 plate, it is preferable that at least one phase difference layer A satisfies equation (7) and at least one other phase difference layer A satisfies equation (8).

[0100] For example, in the dimming device 10d shown in Figure 6, it is preferable that the phase difference layer A16a and the phase difference layer A16b are arranged at an angle (approximately 22.5°) where the orientation angle of the in-plane slow phase axis satisfies the above formula (7), and that the phase difference layer A16c and the phase difference layer A16d are arranged at an angle (approximately 67.5°) where the orientation angle of the in-plane slow phase axis satisfies the above formula (8).

[0101] Furthermore, in the dimming device 10e shown in Figure 7, it is preferable that the phase difference layer A16a and phase difference layer A16b are arranged at an angle (approximately 22.5°) where the orientation angle of the in-plane slow phase axis satisfies the above formula (7), and that the phase difference layer A16c and phase difference layer A16d are arranged at an angle (approximately 67.5°) where the orientation angle of the in-plane slow phase axis satisfies the above formula (8).

[0102] Thus, by having four phase difference layers A and two or four phase difference layers C, and by setting the azimuth angles of the four phase difference layers A as described above, optical compensation for light incident from an oblique direction can be made more precise, and the azimuth angle dependence of transmittance can be made smaller.

[0103] In the example described above, the dimming device has a configuration with four phase difference layers A, in which two of the phase difference layers A are arranged at angles that satisfy the in-plane slow axis orientation angle of equation (7) above (approximately 22.5°), and the other two of the phase difference layers A are arranged at angles that satisfy the in-plane slow axis orientation angle of equation (8) above (approximately 67.5°). However, the device is not limited to this configuration. For example, of the four phase difference layers A, one of the phase difference layers A may be arranged at an angle that satisfies the in-plane slow axis orientation angle of equation (7) above (approximately 22.5°), another of the phase difference layers A may be arranged at an angle that satisfies the in-plane slow axis orientation angle of equation (8) above (approximately 67.5°), and the other phase difference layers A may be arranged at angles that are different from these.

[0104] In the examples described above, the dimming device was configured to have two or four phase difference layers A, but it is not limited to this, and the dimming device of the present invention may have three or five or more phase difference layers A.

[0105] Furthermore, in the examples described above, the in-plane retardation ReA of the phase difference layer A in the dimming device was set to approximately λ / 2 or approximately λ / 4, and the angle of the in-plane slow axis was set to approximately 22.5° or approximately 67.5°. However, these are not limited to these values, and can be set appropriately according to the number of layers of the phase difference layer A, etc.

[0106] Furthermore, in the examples described above, when the dimming device has multiple phase difference layers A, the configuration was assumed to be such that the in-plane retardation ReA of all phase difference layers A has the same value. However, the device is not limited to this configuration, and it may also be configured to have phase difference layers A with different in-plane retardation ReA values.

[0107] Furthermore, when the dimming device has two or more phase difference layers A and / or two or more phase difference layers C, it is preferable that at least one of the phase difference layers A is in contact with either the first liquid crystal optical element 12 or the second liquid crystal optical element 14. For example, in the examples shown in Figures 1 to 3, phase difference layer A16a is in contact with the first liquid crystal optical element 12 and phase difference layer A16b is in contact with the second liquid crystal optical element 14. Also, in the example shown in Figure 5, phase difference layer A16a is in contact with the first liquid crystal optical element 12. Also, in the example shown in Figure 6, phase difference layer A16a is in contact with the first liquid crystal optical element 12 and phase difference layer A16d is in contact with the second liquid crystal optical element 14. Also, in the example shown in Figure 7, phase difference layer A16a is in contact with the first liquid crystal optical element 12.

[0108] Furthermore, the liquid crystal optical element, phase difference layer A, and phase difference layer C may be laminated with an adhesive layer in between. In this invention, even if the liquid crystal optical element and phase difference layer A are in contact with each other via an adhesive layer, they are considered to be in contact with each other.

[0109] Conventional known materials can be used as the adhesive layer, and for example, adhesives or tacks are preferred. As adhesives, acrylic adhesives are preferred. As tacks, water-based adhesives such as polyvinyl alcohol, and curing-type adhesives such as acrylic and epoxy are preferred.

[0110] Furthermore, in addition to the liquid crystal optical element, phase difference layer A, and phase difference layer C mentioned above, the dimming device of the present invention may also have layers that provide various functions. Examples include an ultraviolet cut film that cuts ultraviolet rays and an anti-reflective layer that suppresses reflection.

[0111] [Imaging device] The imaging device of the present invention is an imaging device that includes the light control device of the present invention as described above.

[0112] A specific example of the imaging device of the present invention is a digital camera. As shown in Figure 8, in the digital camera 50, it is preferable to arrange the lens 51, the light control device 10, and the image sensor 53 in that order from the incident side. The light control device 10 and the image sensor 53 are arranged inside the housing 52. With the above configuration, the light control device 10 can provide the digital camera 50 with appropriate light control performance.

[0113] As described above, the dimming device 10 of the present invention has low azimuth dependence of transmittance, and therefore, when applied to an imaging device, it can suppress differences in brightness in the peripheral area of ​​the imaging unit where the influence of obliquely incident light is high.

[0114] In addition to being built into the imaging device, the light control device can be placed at any position on the side of the incident light I from the image sensor, such as on the side of the incident light I from the lens.

[0115] Furthermore, in an imaging device, the light control device may be configured to be able to move in and out of the optical path. Since a light control device using a liquid crystal optical element already contains dye, inserting it into the optical path inevitably sacrifices maximum transmittance. Therefore, a mechanism to retract it from the optical path as needed may be provided.

[0116] [Near-eye display] The near-eye display of the present invention is an imaging device that includes the dimming device of the present invention described above.

[0117] Near-eye displays such as AR (augmented reality) displays and head-mounted displays (HMDs) have a transparent display or screen that is close to the eyes, allowing the user to see the surrounding environment while simultaneously viewing images displayed on the display or projected onto the screen.

[0118] In the near-eye display of the present invention, the dimming device is located on the back side (opposite side from the user) of the area including the display or screen.

[0119] In near-eye displays, the visibility of images displayed on the screen or projected onto the screen is affected by the brightness of the surrounding environment. For example, when a user wearing a near-eye display goes from indoors to outdoors, the brightness of the surrounding environment changes, and the ratio of ambient brightness to image brightness changes, resulting in decreased visibility.

[0120] In contrast, the near-eye display of the present invention has a dimming device, which allows the light transmittance of the dimming device to be controlled according to the brightness of the surrounding environment, thereby adjusting the amount of ambient light reaching the user's eyes and suppressing a decrease in image visibility.

[0121] As described above, the dimming device 10 of the present invention has low azimuth dependence of transmittance, and therefore, when applied to a near-eye display, it can suppress the difference in brightness due to changes in transmitted light intensity within the peripheral field of view perceived by the user wearing the near-eye display.

[0122] The present invention will be specifically described below based on examples. The materials, reagents, amounts and proportions of substances, and procedures shown in the following examples can be modified as appropriate, as long as they do not depart from the spirit of the present invention. Therefore, the present invention is not limited to the following examples.

[0123] [Example 1] <Fabrication of Optical Laminate 1> A cycloolefin polymer film 1 (nx = 1.510, ny = 1.507, nz = 1.507, Re = 275 nm, Rth = 137 nm, Re(450) / Re(550) = 1.0, manufactured by JSR Corporation) was discharged at a rate of 125 W・min / m ２ Corona treatment was performed, and the liquid crystal composition 1 prepared as described below was applied to the corona-treated surface using a #7 wire bar. Next, to dry the solvent of the composition and to allow the liquid crystal compound to be oriented and matured, it was heated with 70°C hot air for 90 seconds, and then irradiated with ultraviolet light (300 mJ / cm²) at 40°C under nitrogen purging with an oxygen concentration of 0.1%. ２A liquid crystal layer 1 (nx = 1.492, ny = 1.492, nz = 1.605, Re = 0 nm, Rth = -180 nm, Re(450) / Re(550) = 1.0) was fabricated by fixing the orientation of the liquid crystal compound, and an optical laminate 1 was created. The cycloolefin polymer film 1 corresponds to phase difference layer A, and the liquid crystal layer 1 corresponds to phase difference layer C.

[0124] -------------------------------------------------- Liquid Crystal Composition 1 -------------------------------------------------- 75.0 parts by mass of the following liquid crystal compound R1 25.0 parts by mass of the following liquid crystal compound R2 5.0 parts by mass of the following photopolymerization initiator S1 2.0 parts by mass of the following photopolymerization initiator S2 2.0 parts by mass of the following orientation aid A1 4.5 parts by mass of the following boronic acid monomer B1 8.0 parts by mass of A-TMMT (manufactured by Shin Nakamura Chemical Industry Co., Ltd.) 426.0 parts by mass of acetone 49.0 parts by mass of PGMEA 14.7 parts by mass of methanol 0.5 parts by mass of the following surfactant P-1 0.4 parts by mass of the following surfactant P-2 --------------------------------------------------

[0125] Liquid crystal compound R1 [a mixture of the following liquid crystal compounds (RA), (RB), and (RC) in a mass ratio of 83:15:2]

[0126] Liquid crystal compound R2 [In the following formula, the group adjacent to the acryloyloxy group represents a propylene group (a group in which a methyl group is substituted for an ethylene group).]

[0127] Photopolymerization initiator S1

[0128] Photopolymerization initiator S2

[0129] Orientation aid A1

[0130] Boronic acid monomer B1

[0131] A-TMMT (manufactured by Shin-Nakamura Chemical Industry Co., Ltd.)

[0132] Surfactant P-1 (weight-average molecular weight 11,200) (The numbers in the formula below represent (mass%).)

[0133] Surfactant P-2 (weight-average molecular weight 15,000) (The numbers in the formula below represent (mass%).)

[0134] <Fabrication of Guest Host Dimming Device 1> The liquid crystal optical element 1 is a vertically aligned nematic (VAN) guest host cell with a cell spacing of 9.0 μm and a pre-tilt angle of 87° with respect to the alignment plane, with a liquid crystal layer provided between two supports on which transparent electrode layers are formed. The guest host liquid crystal mixture used was a commercially available black dye mixture 90700-100 (obtained from Jiangsu Hecheng Display Technology) diluted with host mixture TEC92700-100 to achieve 50% transmission of normal incident light when no voltage is applied.

[0135] The optical laminate 1 (composition: cycloolefin polymer film 1 / liquid crystal layer 1) prepared as described above was bonded to the liquid crystal optical element 1 with an adhesive, with the cycloolefin polymer film side facing 22.5° with respect to the orientation direction in which the guest material of the liquid crystal optical element 1 is tilted (composition: liquid crystal optical element 1 / cycloolefin polymer film 1 / liquid crystal layer 1). Subsequently, the surface of the cycloolefin polymer film 1 of the other optical laminate 1 was bonded to the liquid crystal layer 1 side, with respect to the orientation direction in which the guest material of the liquid crystal optical element 1 is tilted, with respect to 67.5° (composition: liquid crystal optical element 1 / cycloolefin polymer film 1 / liquid crystal layer 1 / cycloolefin polymer film 1 / liquid crystal layer 1). Finally, a liquid crystal optical element 2 was attached to the liquid crystal layer 1 on the opposite surface from the liquid crystal optical element 1 using an adhesive, such that the orientation of the guest material of the liquid crystal optical element 2 is 180° with respect to the orientation of the guest material of the liquid crystal optical element 1. This created a guest-host dimming device 1 (configuration: liquid crystal optical element 1 (orientation 0°) / phase difference layer A (cycloolefin polymer film 1, slow axis 22.5°) / phase difference layer C (liquid crystal layer 1) / phase difference layer A (cycloolefin polymer film 1, slow axis 67.5°) / phase difference layer C (liquid crystal layer 1) / liquid crystal optical element 2 (orientation 180°)). The configuration of the liquid crystal optical element 2 is the same as that of the liquid crystal optical element 1.

[0136] [Example 2] <Fabrication of Optical Laminate 2> Discharge rate of 125 W・min / m for cycloolefin polymer film 2 (nx = 1.510, ny = 1.508, nz = 1.508, Re = 137 nm, Rth = 67 nm, Re(450) / Re(550) = 1.0, manufactured by JSR Corporation) ２ Corona treatment was performed, and the liquid crystal composition 1 prepared above was applied to the corona-treated surface using a #5 wire bar. Next, to dry the solvent of the composition and to allow the liquid crystal compound to be oriented and matured, it was heated with 70°C hot air for 90 seconds, and then irradiated with ultraviolet light (300 mJ / cm²) at 40°C under nitrogen purging with an oxygen concentration of 0.1%. ２The orientation of the liquid crystal compound was fixed by performing the following steps to create a liquid crystal layer 2 (nx = 1.492, ny = 1.492, nz = 1.605, Re = 0 nm, Rth = -120 nm, Re(450) / Re(550) = 1.0), and an optical laminate 2 was fabricated. The cycloolefin polymer film 2 corresponds to phase difference layer A, and the liquid crystal layer 2 corresponds to phase difference layer C.

[0137] <Fabrication of Guest Host Dimming Device 2> The optical laminate 2 fabricated above (composition: cycloolefin polymer film 2 / liquid crystal layer 2) was bonded to the liquid crystal optical element 1 with adhesive, with the cycloolefin polymer film 2 side facing the liquid crystal optical element 1 such that the angle of the in-plane slow axis of the cycloolefin polymer film 2 is 22.5° with respect to the orientation direction in which the guest material of the liquid crystal optical element 1 is tilted (composition: liquid crystal optical element 1 / cycloolefin polymer film 2 / liquid crystal layer 2). Next, the cycloolefin polymer film 2 was bonded to the liquid crystal layer 2 side such that the angle of the in-plane slow axis of the cycloolefin polymer 2 is 22.5° with respect to the orientation direction in which the guest material of the liquid crystal optical element 1 is tilted (composition: liquid crystal optical element 1 / cycloolefin polymer film 2 / liquid crystal layer 2 / cycloolefin polymer film 2). Next, the cycloolefin polymer film 2 side of the other optical laminate 2 was bonded to the outermost cycloolefin polymer film 2 side such that the angle of the slow axis was 67.5° with respect to the orientation direction in which the guest material of the liquid crystal optical element 1 is tilted (configuration: liquid crystal optical element 1 / cycloolefin polymer film 2 / liquid crystal layer 2 / cycloolefin polymer film 2 / cycloolefin polymer film 2 / liquid crystal layer 2). Subsequently, the cycloolefin polymer film 2 was bonded to the outermost liquid crystal layer 2 side such that the angle of the in-plane slow axis was 67.5° with respect to the orientation direction in which the guest material of the liquid crystal optical element 1 is tilted (configuration: liquid crystal optical element 1 / cycloolefin polymer film 2 / liquid crystal layer 2 / cycloolefin polymer film 2 / cycloolefin polymer film 2 / liquid crystal layer 2 / cycloolefin polymer film 2).Finally, the liquid crystal optical element 2 was attached to the outermost cycloolefin polymer film 2 using an adhesive such that the orientation of the guest material of the liquid crystal optical element 2 was 180° with respect to the orientation of the guest material of the liquid crystal optical element 1, thereby fabricating a guest-host dimming device 2 (configuration: liquid crystal optical element 1 (orientation 0°) / phase difference layer A (cycloolefin polymer film 2, slow axis 22.5°) / phase difference layer C (liquid crystal layer 2) / phase difference layer A (cycloolefin polymer film 2, slow axis 22.5°) / phase difference layer A (cycloolefin polymer film 2, slow axis 67.5°) / phase difference layer C (liquid crystal layer 2) / phase difference layer A (cycloolefin polymer film 2, slow axis 67.5°) / liquid crystal optical element 2 (orientation 180°)).

[0138] [Example 3] <Fabrication of Guest Host Dimming Device 3> The cycloolefin polymer film 1 side of the optical laminate 1 (composition: cycloolefin polymer film 1 / liquid crystal layer 1) fabricated above was bonded to the liquid crystal optical element 1 with adhesive so that the angle of the slow axis was 22.5° with respect to the direction in which the guest material of the liquid crystal optical element 1 is tilted (composition: liquid crystal optical element 1 / cycloolefin polymer film 1 / liquid crystal layer 1). Subsequently, the cycloolefin polymer film 1 was bonded to the liquid crystal layer 1 side with adhesive so that the angle of the slow axis was 67.5° with respect to the direction in which the guest material of the liquid crystal optical element 1 is tilted (composition: liquid crystal optical element 1 / cycloolefin polymer film 1 / liquid crystal layer 1 / cycloolefin polymer film 1). Finally, a liquid crystal optical element 2 was attached to the outermost cycloolefin polymer film 1 using an adhesive such that the orientation of the guest material of the liquid crystal optical element 2 was 180° with respect to the orientation direction of the liquid crystal optical element 1, thereby fabricating a guest-host dimming device 3 (configuration: liquid crystal optical element 1 (orientation 0°) / phase difference layer A (cycloolefin polymer film 1, slow axis 22.5°) / phase difference layer C (liquid crystal layer 1) / phase difference layer A (cycloolefin polymer film 1, slow axis 67.5°) / liquid crystal optical element 2 (orientation 180°)).

[0139] [Example 4] <Fabrication of Optical Laminate 3> Discharge rate of 125 W・min / m for cycloolefin polymer film 3 (nx = 1.510, ny = 1.508, nz = 1.508, Re = 134 nm, Rth = 67 nm, Re(450) / Re(550) = 1.0, manufactured by JSR Corporation) ２ Corona treatment was performed, and the liquid crystal composition 3 prepared as described below was applied to the corona-treated surface using a #3 wire bar. Next, to dry the solvent of the composition and to allow the liquid crystal compound to be oriented and matured, it was heated with 70°C hot air for 90 seconds, and then irradiated with ultraviolet light (300 mJ / cm²) at 40°C under nitrogen purging with an oxygen concentration of 0.1%. ２ The orientation of the liquid crystal compound was fixed by performing the following steps to produce a liquid crystal layer 3 (nx = 1.492, ny = 1.492, nz = 1.605, Re = 0 nm, Rth = -90 nm, Re(450) / Re(550) = 1.08), and an optical laminate 3 (cycloolefin polymer film 3 / liquid crystal layer 3) was fabricated. The cycloolefin polymer film 3 corresponds to phase difference layer A, and the liquid crystal layer 3 corresponds to phase difference layer C.

[0140] -------------------------------------------------- Liquid Crystal Composition 3 -------------------------------------------------- • Liquid crystal compound R1 100.0 parts by mass • Photopolymerization initiator S1 5.0 parts by mass • Photopolymerization initiator S2 2.0 parts by mass • Orientation aid A1 2.0 parts by mass • Boronic acid monomer B1 4.5 parts by mass • A-TMMT (manufactured by Shin Nakamura Chemical Industry Co., Ltd.) 8.0 parts by mass • Acetone 426.0 parts by mass • PGMEA 49.0 parts by mass • Methanol 14.7 parts by mass • Surfactant P-1 0.5 parts by mass • Surfactant P-2 0.4 parts by mass --------------------------------------------------

[0141] <Fabrication of Guest Host Dimming Device 4> The cycloolefin polymer film 3 side of the optical laminate 3 (composition: cycloolefin polymer film 3 / liquid crystal layer 3) fabricated above was attached to the liquid crystal optical element 1 with adhesive so that the angle of the slow axis was 22.5° with respect to the direction in which the guest material of the liquid crystal optical element 1 is tilted (composition: liquid crystal optical element 1 / cycloolefin polymer film 3 / liquid crystal layer 3). Subsequently, the cycloolefin polymer film 3 side of the optical laminate 3 was further attached to the liquid crystal layer 3 side with adhesive so that the angle of the slow axis was 22.5° with respect to the direction in which the guest material of the liquid crystal optical element 1 is tilted (composition: liquid crystal optical element 1 / cycloolefin polymer film 3 / liquid crystal layer 3 / cycloolefin polymer film 3 / liquid crystal layer 3). Next, the cycloolefin polymer film 3 of the optical laminate 3 was bonded to the outermost liquid crystal layer 3 using an adhesive so that the angle of the slow axis was 67.5° with respect to the direction in which the guest material of the liquid crystal optical element 1 is tilted (configuration: liquid crystal optical element 1 / cycloolefin polymer film 3 / liquid crystal layer 3 / cycloolefin polymer film 3 / liquid crystal layer 3 / cycloolefin polymer film 3 / liquid crystal layer 3). Next, the cycloolefin polymer film 3 of the optical laminate 3 was bonded to the outermost liquid crystal layer 3 using an adhesive so that the angle of the slow axis was 67.5° with respect to the direction in which the guest material of the liquid crystal optical element 1 is tilted (configuration: liquid crystal optical element 1 / cycloolefin polymer film 3 / liquid crystal layer 3 / cycloolefin polymer film 3 / liquid crystal layer 3 / cycloolefin polymer film 3 / liquid crystal layer 3).Finally, the liquid crystal optical element 2 is bonded to the side of the outermost liquid crystal layer 3 with an adhesive so that the azimuth direction in which the guest material of the liquid crystal optical element 2 tilts is 180° with respect to the azimuth direction in which the guest material of the liquid crystal optical element 1 tilts, and a guest-host dimming device 4 (configuration: liquid crystal optical element 1 (0° alignment) / phase difference layer A (cycloolefin polymer film 3, slow axis 22.5°) / phase difference layer C (liquid crystal layer 3) / phase difference layer A (cycloolefin polymer film 3, slow axis 22.5°) / phase difference layer C (liquid crystal layer 3) / phase difference layer A (cycloolefin polymer film 3, slow axis 67.5°) / phase difference layer C (liquid crystal layer 3) / phase difference layer A (cycloolefin polymer film 3, slow axis 67.5°) / phase difference layer C (liquid crystal layer 3) / liquid crystal optical element 2 (180° alignment)) was fabricated.

[0142] [Example 5] <Fabrication of optical laminate 4> For a cycloolefin polymer film 4 (nx = 1.510, ny = 1.508, nz = 1.508, Re = 124 nm, Rth = 62 nm, Re(450) / Re(550) = 1.0, manufactured by JSR Corporation), a corona treatment was performed at a discharge amount of 125 W·min / m ２ and the liquid crystal composition 3 prepared above was applied to the surface subjected to the corona treatment with a #3.4 wire bar. Next, for drying the solvent of the composition and aging the alignment of the liquid crystal compound, after heating with warm air at 70°C for 90 seconds, ultraviolet irradiation (300 mJ / cm ２ was performed at 40°C under a nitrogen purge with an oxygen concentration of 0.1% to fix the alignment of the liquid crystal compound and a liquid crystal layer 4 (nx = 1.492, ny = 1.492, nz = 1.605, Re = 0 nm, Rth = -96 nm, Re(450) / Re(550) = 1.08) was fabricated, and an optical laminate 4 (cycloolefin polymer film 4 / liquid crystal layer 4) was fabricated. The cycloolefin polymer film 4 corresponds to the phase difference layer A, and the liquid crystal layer 4 corresponds to the phase difference layer C.

[0143] <Fabrication of Guest Host Dimmer 5> The guest host dimmer 5 (configuration: liquid crystal optical element 1 (0° orientation) / phase difference layer A (cycloolefin polymer film 4, slow axis 22.5°) / phase difference layer C (liquid crystal layer 4) / phase difference layer A (cycloolefin polymer film 4, slow axis 22.5°) / phase difference layer C (liquid crystal layer 4) / phase difference layer A (cycloolefin polymer film 4, slow axis 22.5°) / phase difference layer C (liquid crystal layer 4) / phase difference layer A (cycloolefin polymer film 4, slow axis 67.5°) / phase difference layer C (liquid crystal layer 4) / phase difference layer C (liquid crystal layer 4) / liquid crystal optical element 2 (180° orientation)) was fabricated in the same manner as in Example 4, except that the optical laminate 4 fabricated above was used instead of the optical laminate 3 in Example 4.

[0144] [Comparative Example 1] A cycloolefin polymer film 1 was bonded to the liquid crystal optical element 1 described above using an adhesive such that the angle of the slow axis was 45° with respect to the orientation direction in which the guest material of the liquid crystal optical element 1 is tilted (configuration: liquid crystal optical element 1 / cycloolefin polymer film 1). Subsequently, a liquid crystal optical element 2 was bonded to the cycloolefin polymer film 1 using an adhesive such that the orientation direction in which the guest material of the liquid crystal optical element 2 is tilted was 180° with respect to the orientation direction in which the guest material of the liquid crystal optical element 1 is tilted, thereby fabricating the guest host dimming device of Comparative Example 1 (configuration: liquid crystal optical element 1 (orientation 0°) / phase difference layer A (cycloolefin polymer film 1, slow axis 45°) / liquid crystal optical element 2 (orientation 180°)).

[0145] [Comparative Example 2] <Preparation of Optical Laminate 5> The above cycloolefin polymer film 1 was prepared with a discharge rate of 125 W・min / m ２ Corona treatment was performed, and the liquid crystal composition 1 prepared above was applied to the corona-treated surface using a #2 wire bar. Next, to dry the solvent of the composition and to allow the liquid crystal compound to be oriented and matured, it was heated with 70°C hot air for 90 seconds, and then irradiated with ultraviolet light (300 mJ / cm²) at 40°C under nitrogen purging with an oxygen concentration of 0.1%. ２The orientation of the liquid crystal compound was fixed by performing the following steps to produce a liquid crystal layer 5 (nx = 1.492, ny = 1.492, nz = 1.605, Re = 0 nm, Rth = -100 nm, Re(450) / Re(550) = 1.0), and an optical laminate 5 (cycloolefin polymer film 1 / liquid crystal layer 5) was fabricated.

[0146] <Fabrication of Guest Host Light Control Device 6> The cycloolefin polymer film 1 side of the optical laminate 5 (composition: cycloolefin polymer film 1 / liquid crystal layer 5) fabricated above was bonded to the liquid crystal optical element 1 with an adhesive so that the angle of the slow axis was 45° with respect to the orientation direction of the liquid crystal optical element 1 (composition: liquid crystal optical element 1 / cycloolefin polymer film 1 / liquid crystal layer 5). Next, the liquid crystal optical element 2 was bonded to the liquid crystal layer 5 side with an adhesive so that its orientation direction was 180° with respect to the orientation direction of the liquid crystal optical element 1, thereby fabricating the guest host light control device 6 of Comparative Example 2 (composition: liquid crystal optical element 1 (orientation 0°) / phase difference layer A (cycloolefin polymer film 1, slow axis 45°) / phase difference layer C (liquid crystal layer 5) / liquid crystal optical element 2 (orientation 180°)).

[0147] [Evaluation] <Azimuth angle dependence of transmittance> For the guest-host dimming devices fabricated in Examples 1 to 5 and Comparative Examples 1 to 2, light was incident using a light source with a wavelength of 550 nm, and a voltage was applied so that the transmittance with respect to the normal incident light was 12.5%. Observations were made from positions with an azimuth angle of 0°, 45°, 90°, 135°, 225°, 270°, and 315° at an extreme angle of 30°, and the azimuth angle dependence of transmittance was evaluated using the following index. Note that the normal direction of the guest-host dimming device is set to an extreme angle of 0°, and the azimuth angle is set to the direction in which the guest material of the liquid crystal optical element 1 in the guest-host dimming device is tilted.

[0148] The results are shown in Table 1. In Table 1, the "Layer Configuration" column represents the layer configuration of the phase difference layer placed between liquid crystal optical element 1 and liquid crystal optical element 2. Phase difference layer A is denoted as "A" and phase difference layer C as "C," and the stacking order from the liquid crystal optical element 1 side is represented using "A" and "C."

[0149] (Evaluation Criteria) AA: Very little difference in transmitted light intensity between observation positions. A: Little difference in transmitted light intensity between observation positions. B: Slight difference in transmitted light intensity between observation positions. C: Very large difference in transmitted light intensity between observation positions.

[0150]

[0151] Table 1 shows that the embodiments of the present invention exhibit lower azimuth dependence of transmittance compared to the comparative examples.

[0152] Furthermore, from Example 3, it can be seen that it is preferable to have two phase difference layers A, where one phase difference layer A satisfies equation (7) and the other phase difference layer A satisfies equation (8).

[0153] Furthermore, from Example 1, it can be seen that it is preferable to have two phase difference layers A and two phase difference layers C, and to have them in the order of phase difference layer A, phase difference layer C, phase difference layer A, phase difference layer C, and it is preferable that phase difference layer A satisfies formula (3) and phase difference layer C satisfies formula (4), and it is preferable that one phase difference layer A satisfies formula (7) and the other phase difference layer A satisfies formula (8).

[0154] Furthermore, from Example 2, it can be seen that it is preferable to have four phase difference layers A and two phase difference layers C, in the order of phase difference layer A, phase difference layer C, phase difference layer A, phase difference layer A, phase difference layer C, and phase difference layer A, and that it is preferable for phase difference layer A to satisfy formula (5) and phase difference layer C to satisfy formula (6), and that it is preferable for at least one layer of phase difference layer A to satisfy formula (7) and at least one other layer of phase difference layer A to satisfy formula (8).

[0155] Furthermore, from Examples 4 and 5, it can be seen that the phase difference layer A has four layers and the phase difference layer C has four layers, preferably arranged in the order of phase difference layer A, phase difference layer C, phase difference layer A, phase difference layer C, phase difference layer A, phase difference layer C, phase difference layer A, phase difference layer C, and phase difference layer C. It is also preferable that phase difference layer A satisfies formula (5) and phase difference layer C satisfies formula (6). Furthermore, it is preferable that at least one layer of phase difference layer A satisfies formula (7) and at least one other layer of phase difference layer A satisfies formula (8).

[0156] <Evaluation by Simulation> The configurations of Example 1 and Comparative Example 1 were modeled and simulations were performed. The results of calculating the transmittance by changing the polar angle and azimuthal angle are shown as contour plots in Figures 9 and 10. The liquid crystal molecules and guest materials of liquid crystal optical element 1 and liquid crystal optical element 2 were modeled so that the transmittance in the normal direction (polar angle 0°) is 12.5%. Optics Master from SHINTEC OPTICS was used for the simulation.

[0157] In the figure, the transmittance along the thick dashed line corresponds to the transmittance for each azimuth angle at a certain polar angle. In Figure 9 (Example 1), there are few intersections between the thick dashed line and the contour lines, indicating that the change in transmittance is small even when the azimuth angle changes. On the other hand, in Figure 10 (Comparative Example 1), there are many intersections between the thick dashed line and the contour lines, indicating that the transmittance changes significantly when the azimuth angle changes, even if the polar angle remains constant.

[0158] [Example 6] <Preparation of optical laminate 6> The above cycloolefin polymer film 1 was subjected to a discharge rate of 125 W・min / m ２ Corona treatment is performed, and the liquid crystal composition 2 prepared below is applied to the corona-treated surface using a #7 wire bar. Then, in order to dry the solvent of the composition and to allow the liquid crystal compound to be oriented and matured, it is heated with hot air at 70°C for 90 seconds, and then irradiated with ultraviolet light (300 mJ / cm²) at 40°C under nitrogen purging with an oxygen concentration of 0.1%. ２ The orientation of the liquid crystal compound is fixed by performing the following steps to produce a liquid crystal layer 6 (nx = 1.492, ny = 1.492, nz = 1.605, Re = 0 nm, Rth = -180 nm, Re(450) / Re(550) = 0.83), and an optical laminate 6 (cycloolefin polymer film 1 / liquid crystal layer 6) is fabricated. The cycloolefin polymer film 1 corresponds to phase difference layer A, and the liquid crystal layer 6 corresponds to phase difference layer C.

[0159] -------------------------------------------------- Liquid Crystal Composition 2 -------------------------------------------------- • Liquid crystal compound R1 25.0 parts by mass • Liquid crystal compound R2 75.0 parts by mass • Photopolymerization initiator S1 5.0 parts by mass • Photopolymerization initiator S2 2.0 parts by mass • Orientation aid A1 2.0 parts by mass • Boronic acid monomer B1 4.5 parts by mass • A-TMMT (manufactured by Shin Nakamura Chemical Industry Co., Ltd.) 8.0 parts by mass • Acetone 426.0 parts by mass • PGMEA 49.0 parts by mass • Methanol 14.7 parts by mass • Surfactant P-1 0.5 parts by mass • Surfactant P-2 0.4 parts by mass --------------------------------------------------

[0160] <Fabrication of Guest Host Dimmer 7> The guest host dimmer 7 (configuration: liquid crystal optical element 1 (orientation 0°) / phase difference layer A (cycloolefin polymer film 1, slow axis 22.5°) / phase difference layer C (liquid crystal layer 6) / phase difference layer A (cycloolefin polymer film 1, slow axis 67.5°) / phase difference layer C (liquid crystal layer 6) / liquid crystal optical element 2 (orientation 180°)) is fabricated in the same manner as in Example 1, except that the optical laminate 6 fabricated as described above is used instead of the optical laminate 1 in Example 1.

[0161] [Example 7] <Preparation of optical laminate 7> The above cycloolefin polymer film 1 was subjected to a discharge rate of 125 W・min / m ２ Corona treatment is performed, and the liquid crystal composition 3 prepared above is applied to the corona-treated surface using a #7 wire bar. Next, to dry the solvent of the composition and to allow the liquid crystal compound to be oriented and matured, it is heated with 70°C hot air for 90 seconds, and then irradiated with ultraviolet light (300 mJ / cm²) at 40°C with an oxygen concentration of 0.1% under nitrogen purging. ２The orientation of the liquid crystal compound is fixed by performing the following steps to produce a liquid crystal layer 7 (nx = 1.492, ny = 1.492, nz = 1.605, Re = 0 nm, Rth = -180 nm, Re(450) / Re(550) = 1.08), and an optical laminate 7 (cycloolefin polymer film 1 / liquid crystal layer 7) is fabricated. The cycloolefin polymer film 1 corresponds to phase difference layer A, and the liquid crystal layer 7 corresponds to phase difference layer C.

[0162] <Fabrication of Guest Host Dimmer 8> Except for using the optical laminate 7 fabricated above instead of the optical laminate 1 in Example 1, the guest host dimmer 8 (configuration: liquid crystal optical element 1 (orientation 0°) / phase difference layer A (cycloolefin polymer film 1, slow axis 22.5°) / phase difference layer C (liquid crystal layer 7) / phase difference layer A (cycloolefin polymer film 1, slow axis 67.5°) / phase difference layer A (liquid crystal layer 7) / liquid crystal optical element 2 (orientation 180°)) is fabricated in the same manner as in Example 1.

[0163] [Evaluation] <Azimuth Dependence of Transmittance> The azimuth dependence of transmittance was evaluated for the guest host dimming devices fabricated in Examples 6 and 7 using the same method as described above. The evaluation is shown in Table 2. In Table 2, the wavelength dispersion item is the value of Re(450) / Re(550).

[0164]

[0165] Table 2 shows that, similar to Example 1, Examples 6 and 7 exhibit low azimuth dependence of transmittance.

[0166] Furthermore, Example 6, in which the phase difference layer C has inverse wavelength dispersion (Re(450) / Re(550) < 1), is preferable to Examples 1 and 7 because it shows less change in color when observed at different polar angles. The effects of the present invention are clear from these results.

[0167] 10a-10e Light control device 12 First liquid crystal optical element 14 Second liquid crystal optical element 16a-16d Phase difference layer A 18a-18d Phase difference layer C 30 Liquid crystal molecule 32 Dichroic dye molecule 50 Digital camera (imaging device) 51 Lens 52 Housing 53 Imaging sensor 110 Light control device 112 First liquid crystal optical element 114 Second liquid crystal optical element 116 Phase difference layer

Claims

1. A dimming device comprising a first liquid crystal optical element and a second liquid crystal optical element, wherein the first liquid crystal optical element and the second liquid crystal optical element each have a liquid crystal layer comprising a liquid crystal material and a guest material, the first liquid crystal optical element and the second liquid crystal optical element can change the orientation direction of the guest material by applying a voltage, the angle between the orientation direction in which the guest material in the first liquid crystal optical element tilts and the orientation direction in which the guest material in the second liquid crystal optical element tilts when a voltage is applied is 170° to 190°, and between the first liquid crystal optical element and the second liquid crystal optical element there are at least two phase difference layers A and at least one phase difference layer C, the phase difference layers A and C and the phase difference layer A are at least in this order, the phase difference layer A satisfies the following formula (1), and the phase difference layer C satisfies the following formula (2). nxA > nzA ≥ nyA Equation (1) nzC > nxC ≥ nyC Equation (2) Here, in Equation (1), nxA represents the refractive index of the phase difference layer A at a wavelength of 550 nm in the slow axis direction within the plane, nyA represents the refractive index of the phase difference layer A in a direction perpendicular to the slow axis direction within the plane, and nzA represents the refractive index of the phase difference layer A out of the plane. Also, in Equation (2), nxC represents the refractive index of the phase difference layer C at a wavelength of 550 nm in the slow axis direction within the plane, nyC represents the refractive index of the phase difference layer C in a direction perpendicular to the slow axis direction within the plane, and nzC represents the refractive index of the phase difference layer C out of the plane.

2. The dimming device according to claim 1, wherein at least one layer of the phase difference layer A is in contact with one of the first liquid crystal optical element and the second liquid crystal optical element.

3. The dimming device according to claim 1, comprising two or more phase difference layers A and two or more phase difference layers C.

4. The dimming device according to claim 3, comprising at least the phase difference layer A, the phase difference layer C, the phase difference layer A, and the phase difference layer C in this order.

5. The dimming device according to claim 1, comprising four or more phase difference layers A and two or more phase difference layers C.

6. The dimming device according to claim 5, comprising at least the phase difference layer A, the phase difference layer C, the phase difference layer A, the phase difference layer A, the phase difference layer C, and the phase difference layer A in this order.

7. The dimming device according to claim 1, comprising four or more phase difference layers A and four or more phase difference layers C.

8. The dimming device according to claim 7, comprising at least the phase difference layer A, the phase difference layer C, the phase difference layer A, the phase difference layer C, the phase difference layer A, the phase difference layer C, the phase difference layer A, and the phase difference layer C in this order.

9. A dimming device according to any one of claims 1 to 4, wherein the phase difference layer A satisfies the following formula (3), and the phase difference layer C satisfies the following formula (4): 225 nm < ReA < 325 nm Formula (3) -500 nm < RthC < -100 nm Formula (4) Here, in formula (3), ReA represents the in-plane retardation of the phase difference layer A at a wavelength of 550 nm. Also, in formula (4), RthC represents the thickness-direction retardation of the phase difference layer C at a wavelength of 550 nm.

10. A dimming device according to any one of claims 1 to 8, wherein the phase difference layer A satisfies the following formula (5), and the phase difference layer C satisfies the following formula (6). 100 nm < ReA < 180 nm Formula (5) -250 nm < RthC < -50 nm Formula (6) Here, in formula (5), ReA represents the in-plane retardation of the phase difference layer A at a wavelength of 550 nm. Also, in formula (6), RthC represents the thickness-direction retardation of the phase difference layer C at a wavelength of 550 nm.

11. A dimming device according to any one of claims 1 to 8, wherein the phase difference layer A comprises two or more layers, at least one of the phase difference layer A satisfies the following formula (7), and at least one other layer of the phase difference layer A satisfies the following formula (8). 17.5° < D(A) < 27.5° Formula (7) 62.5° < D(A) < 72.5° Formula (8) Here, D(A) represents the angle of the orientation of the lagging axis of the phase difference layer A with respect to the orientation direction in which the guest material in the first liquid crystal optical element tilts when a voltage is applied.

12. The dimming device according to any one of claims 1 to 8, wherein the guest material is a dichroic dye molecule.

13. An imaging apparatus including a dimming device according to any one of claims 1 to 8.

14. A near-eye display comprising a dimming device according to any one of claims 1 to 8.

Images