Dimming device, imaging device, and near-eye display

Abstract

The purpose of the present invention is to provide a dimming device that has a small azimuth angle dependence of a hue of light emitted in an oblique direction. This dimming device comprises a first liquid crystal optical element (12) and a second liquid crystal optical element (14), the first liquid crystal optical element (12) and the second liquid crystal optical element (14) have a liquid crystal layer (18) containing a liquid crystal material (30) and a guest material (32), the first liquid crystal optical element (12) and the second liquid crystal optical element (14) are such that an alignment direction of the guest material (32) can be changed by applying a voltage thereto, an angle formed by the orientation direction in which the guest material (32) in the first liquid crystal optical element (12) is inclined and the orientation direction in which the guest material (32) in the second liquid crystal optical element (14) is inclined is 170° to 190° when the voltage is applied, at least one liquid crystal layer B (18) is included between the first liquid crystal optical element (12) and the second liquid crystal optical element (14), and the liquid crystal layer B (18) is a layer obtained by immobilizing a disk-shaped liquid crystal compound (22) having a twisted alignment at 80° to 100° with the thickness direction as the helical axis.

Description

Dimming 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 an imaging device such as a camera, a dimming device called a neutral density filter, which can uniformly reduce or change the amount of light regardless of wavelength, is sometimes used for imparting effects to captured images. Neutral density filters are also referred to as ND filters (Neutral-density filters), neutral density filters, and the like.

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

[0004] International Publication No. 2017 / 172277

[0005] According to studies by the present inventors, it has been found that in a dimming device using two guest-host liquid crystal devices, in a configuration in which only a half-wave plate is disposed between the two guest-host liquid crystal devices, the color tone of light emitted in an oblique direction greatly varies depending on the azimuth angle.

[0006] An object of the present invention is to provide a dimming device in which the azimuth dependence of the color tone of light emitted in an oblique direction is small.

[0007] As a result of intensive studies by the inventors on the above object, it has been found that the above object can be achieved 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 each have 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 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 at least one liquid crystal layer B is included between the first liquid crystal optical element and the second liquid crystal optical element, the liquid crystal layer B being a layer in which a disc-shaped liquid crystal compound is fixed, which is twisted and oriented at 80° to 100° with the thickness direction as the helical axis. [2] The dimming device according to [1], wherein the liquid crystal layer B satisfies the following formula. 1000nm ≤ Δn(550) × d ≤ 100000nm Here, Δn(X) represents the refractive index anisotropy of the liquid crystal layer B at a wavelength of X nm, and d represents the thickness of the liquid crystal layer B. [3] A dimming device according to [1] or [2], wherein the liquid crystal layer B satisfies the following formula: 1500nm ≤ Δn(550) × d ≤ 100000nm Here, Δn(X) represents the refractive index anisotropy of the liquid crystal layer B at a wavelength of X nm, and d represents the thickness of the liquid crystal layer B. [4] A dimming device according to any one of [1] to [3], wherein the liquid crystal layer B satisfies the following formula: 1.20 ≤ Δn(400) / Δn(550) ≤ 4.85 Here, Δn(X) represents the refractive index anisotropy of the liquid crystal layer B at a wavelength of X nm. [5] A dimming device according to any one of [1] to [4], wherein the guest material is a dichroic dye molecule. [6] An imaging device including a dimming device as described in any of [1] to [5]. [7] A near-eye display including a dimming device as described in any of [1] to [5].

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

[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 an example of an imaging device having the dimming device of the present invention. Figure 6 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, visible light refers to electromagnetic waves with wavelengths visible to the human eye, specifically light in the wavelength range of 380 to 780 nm.

[0017] 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 "lagging axis" refers to the direction in which the refractive index is maximized in the element. The "leading axis" refers to the direction in which the refractive index is minimized in the element.

[0018] <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.

[0019] 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

[0020] 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.

[0021] [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 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 the dimming device includes at least one liquid crystal layer B between the first liquid crystal optical element and the second liquid crystal optical element, the liquid crystal layer B being a layer in which a disc-shaped liquid crystal compound is fixed, which is twisted and oriented at 80° to 100° with the thickness direction as the helical axis.

[0022] 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.

[0023] The dimming device 10a shown in Figure 1 comprises a first liquid crystal optical element 12, a liquid crystal layer B18, and a second liquid crystal optical element 14 in this order. That is, the dimming device 10a has a liquid crystal layer B18 between the first liquid crystal optical element 12 and the second liquid crystal optical element 14. In the illustrated example, the first liquid crystal optical element 12 and the liquid crystal layer B18, and the liquid crystal layer B18 and the second liquid crystal optical element 14 are in direct contact, but may also be spaced apart. Furthermore, the first liquid crystal optical element 12 and the liquid crystal layer B18, and the liquid crystal layer B18 and the second liquid crystal optical element 14 may be in contact via an adhesive layer.

[0024] <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.

[0025] 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.

[0026] 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.

[0027] 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 voltage above a certain level (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 parallel"). 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.

[0028] 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.

[0029] 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 do not absorb much 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 diagonally, 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.

[0030] 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°.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] Furthermore, 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. In other words, in the dimming device 10, the inclination angle of the liquid crystal molecules 30 and dichroic dye molecules 32 in the liquid crystal layer of the first liquid crystal optical element 12 with respect to the surface, and the inclination angle of the liquid crystal molecules 30 and dichroic dye molecules 32 in the liquid crystal layer of the second liquid crystal optical element 14 with respect to the surface, may be the same or different at a given moment.

[0035] As the liquid crystal optical element, a conventionally known dimming element having a liquid crystal layer containing liquid crystal molecules and a guest material can be used as appropriate. Furthermore, as the liquid crystal composition containing liquid crystal molecules and a guest material, a known guest-host liquid crystal composition conventionally used in liquid crystal dimming elements can be used. As for the combination of guest material and host material, any combination of positive or negative guest material and positive or negative host material can be used. Because of the good response characteristics to voltage application, the host material is preferably negative, for example, a vertically aligned nematic guest-host liquid crystal is preferred.

[0036] <Liquid Crystal Layer B> Liquid crystal layer B18 is disposed between the first liquid crystal optical element 12 and the second liquid crystal optical element 14. Liquid crystal layer B18 is a layer formed using a liquid crystal composition containing a disc-shaped liquid crystal compound 22, in which the disc-shaped liquid crystal compound 22 is fixed in a twisted orientation of 80° to 100° with the thickness direction as the helical axis. It is preferable that liquid crystal layer B18 transmits incident linearly polarized light with its polarization direction rotated by approximately 90°.

[0037] Specifically, as shown in Figure 1, in the liquid crystal layer B18, the disc-shaped liquid crystal compound 22 has an upright disc surface, and the disc surface is oriented parallel to the thickness direction. Furthermore, near the surface on the first liquid crystal optical element 12 side, the molecular axes originating from the disc-shaped liquid crystal compound 22 are uniformly oriented in one direction within the plane, in the illustrated example, in the left-right direction in the figure. On the other hand, near the surface on the second liquid crystal optical element 14 side, the molecular axes of the disc-shaped liquid crystal compound 22 are uniformly oriented in one direction within the plane, in the illustrated example, in the direction perpendicular to the plane of the paper. Therefore, in the liquid crystal layer B18, the orientation direction of the disc-shaped liquid crystal compound 22 on the first liquid crystal optical element 12 side and the orientation direction of the disc-shaped liquid crystal compound 22 on the second liquid crystal optical element 14 side are approximately orthogonal (intersecting at 80° to 100°).

[0038] The molecular axis originating from the disc-shaped liquid crystal compound 22 is the axis perpendicular to the disc surface, the so-called phase-advancing axis. In the following explanation, the molecular axis originating from the disc-shaped liquid crystal compound 22 will also be referred to as the "molecular axis of the disc-shaped liquid crystal compound 22" or simply the "molecular axis." Therefore, in the liquid crystal layer B18, the molecular axis of the disc-shaped liquid crystal compound 22 is perpendicular to the thickness direction.

[0039] Furthermore, in the thickness direction of the liquid crystal layer B18, the disc-shaped liquid crystal compounds 22 are arranged in a spiral structure with the thickness direction as the helical axis, and the orientation of the molecular axes of the disc-shaped liquid crystal compounds 22 gradually changes from the first liquid crystal optical element 12 side to the second liquid crystal optical element 14 side. Therefore, the sum of the angles between the molecular axes of adjacent disc-shaped liquid crystal compounds 22 in the thickness direction over the entire thickness direction is approximately 90°, specifically between 80° and 100°. Thus, the angle obtained by summing the angles between the molecular axes of adjacent disc-shaped liquid crystal compounds 22 in the thickness direction over the entire thickness direction is defined as the twist angle of the liquid crystal layer B18.

[0040] The twist angle of the liquid crystal layer B18 is 80° to 100°, preferably 85° to 95°, and more preferably 89° to 91°.

[0041] The twist angle of the liquid crystal layer B18 can be measured using AxoMetrics' AxoScan (polarimeter) device and their device analysis software.

[0042] <Operation of the light modulating device> Next, the operation of the light modulating device of the present invention will be described with reference to FIGS. 1 to 4.

[0043] First, the operation on light incident from a direction perpendicular to the surface of the light modulating device 10a (the first liquid crystal optical element 12 side) will be described.

[0044] As shown in FIG. 1, when no voltage is applied to the first liquid crystal optical element 12 and the second liquid crystal optical element 14, non-polarized light incident from the first liquid crystal optical element 12 side is transmitted as non-polarized light without being substantially absorbed by the first liquid crystal optical element 12. After the non-polarized light passes through the liquid crystal layer B18 while remaining non-polarized, it is transmitted through the second liquid crystal optical element 14 as non-polarized light without being substantially absorbed by the second liquid crystal optical element 14. Accordingly, the light modulating device 10a transmits light with extremely high transmittance.

[0045] Next, as shown in FIG. 2, when a maximum voltage is applied to the first liquid crystal optical element 12 and the second liquid crystal optical element 14, as shown in FIG. 4, the first liquid crystal optical element 12 absorbs, among the non-polarized light incident from the first liquid crystal optical element 12 side, the linearly polarized light component in the alignment azimuth direction of the dichroic dye molecules 32. Therefore, light that has passed through the first liquid crystal optical element 12 becomes linearly polarized light X1 having a polarization direction orthogonal to the alignment azimuth direction of the dichroic dye molecules 32, and is incident on the liquid crystal layer B18. The liquid crystal layer B18 is a layer formed by immobilizing discotic liquid crystal compounds 22 that are twisted and aligned at 80° to 100° with the thickness direction as a helical axis. Therefore, when the linearly polarized light X1 is incident on the liquid crystal layer B18, its polarization direction is rotated by approximately 90° to become linearly polarized light X2. The alignment azimuth direction of the dichroic dye molecules 32 in the second liquid crystal optical element 14 differs by approximately 180° from the alignment azimuth direction of the dichroic dye molecules 32 in the first liquid crystal optical element 12, and is substantially parallel to the polarization direction of the linearly polarized light X2. Therefore, the linearly polarized light X2 is absorbed by the second liquid crystal optical element 14. Accordingly, the transmittance of the light modulating device 10a becomes extremely low.

[0046] Next, as shown in FIG. 3, in a state where 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, among non-polarized light incident from the first liquid crystal optical element 12 side, part of the linearly polarized light component in the alignment azimuth direction of the dichroic dye molecules 32 is absorbed. Therefore, the light passing through the first liquid crystal optical element 12 has more linearly polarized light components substantially parallel to the linearly polarized light X1 than the linearly polarized light component orthogonal thereto (the component parallel to X2), and enters the liquid crystal layer B18. The liquid crystal layer B18 rotates this light by approximately 90°, and converts it into light having more linearly polarized light components substantially parallel to the linearly polarized light X2 than the linearly polarized light component orthogonal thereto (the component parallel to X1). This light enters the second liquid crystal optical element 14, part of the linearly polarized light component substantially parallel to X2 is absorbed, and the remaining part of the linearly polarized light component substantially parallel to X2 and the linearly polarized light component substantially orthogonal to X2 are transmitted. Therefore, the transmittance of the light control device 10a is lower than that when no voltage is applied, and higher than that when the maximum voltage is applied, and the transmittance can be adjusted by the applied voltage.

[0047] Here, in the case of a configuration having only the retardation layer A116 that is a λ / 2 plate between the first liquid crystal optical element 112 and the second liquid crystal optical element 114, as in the conventional light control device 110 (see FIG. 6), the retardation provided by the retardation layer A116 to light obliquely incident on the surface of the light control device 110 (the first liquid crystal optical element 112) deviates from λ / 2. Furthermore, it has been found that the amount of deviation varies depending on the azimuth direction of the incident light, and further varies depending on the wavelength of the incident light. That is, even when the angle (polar angle) of the incident light with respect to the normal to the surface of the light control device 110 (the first liquid crystal optical element 112) is constant, the retardation that the retardation layer A116 provides to light varies depending on the azimuth angle and wavelength of the incident light. Therefore, the polarization state of the light incident on the second liquid crystal optical element 114 varies depending on the azimuth angle and wavelength of the incident light, and the amount of light absorbed by the second liquid crystal optical element 114 also varies. Accordingly, it has been found that the ratio of transmittance for each wavelength varies depending on the azimuth angle of the incident light. As a result, it has been found that the color tone of the emitted light greatly changes depending on the azimuth angle.

[0048] In contrast, the dimming device 10a of the present invention has a liquid crystal layer B18 between the first liquid crystal optical element 12 and the second liquid crystal optical element 14, in which a disc-shaped liquid crystal compound 22 is twisted and oriented at an angle of 80° to 100°.

[0049] The liquid crystal layer B18, in which the disc-shaped liquid crystal compound 22 is twisted and oriented at 80° to 100°, exhibits less wavelength dependence of the amount of rotation that rotates the polarization direction of incident linearly polarized light compared to a λ / 2 plate. Furthermore, since the liquid crystal layer B18 is oriented so that the disc-shaped liquid crystal compound 22 has a disc surface parallel to the thickness direction, the phase difference acting on light incident from an oblique direction can be made the same as when the light is incident perpendicularly, regardless of the azimuth angle. Therefore, the wavelength dependence of the amount of rotation that rotates the polarization direction of linearly polarized light incident from an oblique direction is also reduced. Consequently, the change in the polarization state of light incident on the second liquid crystal optical element 14 from an oblique direction due to the azimuth angle and wavelength becomes small, and the amount of light absorbed by the second liquid crystal optical element 14 becomes approximately constant. Therefore, the dimming device 10a of the present invention can reduce the azimuth angle dependence and wavelength dependence of light transmittance, and can reduce the azimuth angle dependence of the color of light emitted in an oblique direction.

[0050] In the example shown in Figure 2, the orientation direction of the molecular axis of the disc-shaped liquid crystal compound 22 on the first liquid crystal optical element 12 side of the liquid crystal layer B18 is assumed to be approximately parallel to the orientation direction of the liquid crystal molecules 30 and dichroic dye molecules 32 of the first liquid crystal optical element 12 when a voltage is applied. However, the example is not limited to this, and the angle between the orientation direction of the molecular axis of the disc-shaped liquid crystal compound 22 on the first liquid crystal optical element 12 side of the liquid crystal layer B18 and the orientation direction of the liquid crystal molecules 30 and dichroic dye molecules 32 of the first liquid crystal optical element 12 when a voltage is applied can be any angle. For example, the orientation direction of the molecular axis of the disc-shaped liquid crystal compound 22 on the second liquid crystal optical element 14 side of the liquid crystal layer B18 may be approximately parallel to the orientation direction of the liquid crystal molecules 30 and dichroic dye molecules 32 of the second liquid crystal optical element 14 when a voltage is applied.

[0051] Furthermore, in the example shown in Figure 1, the twisting direction of the disc-shaped liquid crystal compound 22 in the liquid crystal layer B18 is shown as a left-handed twist (counterclockwise) from top to bottom in the figure, but it is not limited to this and may also be a right-handed twist (clockwise).

[0052] <Disk-shaped liquid crystal compound> The type of disc-shaped liquid crystal compound used in liquid crystal layer B is not particularly limited. Furthermore, two or more types of disc-shaped liquid crystal compounds may be used.

[0053] Furthermore, the disc-shaped liquid crystal compound may have polymerizable groups. The type of polymerizable group is not particularly limited, but functional groups capable of addition polymerization are preferred, and polymerizable ethylenically unsaturated groups or cyclic polymerizable groups are more preferred. More specifically, preferred polymerizable groups are (meth)acryloyl groups, vinyl groups, styryl groups, allyl groups, epoxy groups, or oxetane groups, with (meth)acryloyl groups being more preferred. In this specification, "(meth)acryloyl" is a notation that represents "acryloyl" or "methacryloyl".

[0054] The number of polymerizable groups in the disc-shaped liquid crystal compound is not particularly limited, but two or more is preferred. There is no particular upper limit, but it is often 10 or less.

[0055] As disc-shaped liquid crystal compounds, those described in Japanese Patent Publication No. 2007-108732 and Japanese Patent Publication No. 2010-244038 can be preferably used.

[0056] Furthermore, it is preferable that the liquid crystal layer B satisfies the following equation (1): 1.20 ≤ Δn(400) / Δn(550) ≤ 4.85 ...Equation (1) Here, Δn(X) represents the refractive index anisotropy of the liquid crystal layer B at a wavelength of X nm.

[0057] By satisfying equation (1) above, the azimuthal angle dependence of the color of light emitted in an oblique direction can be further reduced.

[0058] From the viewpoint of reducing the azimuth dependence of the color of light, Δn(400) / Δn(550) is more preferably 1.25 or more and 4.0 or less, and even more preferably 1.30 or more and 3.0 or less.

[0059] Furthermore, the optical properties of liquid crystal layer B can also be determined using AxoScan from Axometrics and its analysis software (Multi-Layer Analysis). The Δn(550)×d and Δn(400)×d of the rod-shaped liquid crystal layer can be determined, and from their ratio, Δn(400) / Δn(550) can also be calculated.

[0060] Here, it is preferable that the liquid crystal layer B satisfies equation (2) below, and more preferably that it satisfies equation (3) below. 1000 nm ≤ Δn(550) × d ≤ 100000 nm ... Equation (2) 1500 nm ≤ Δn(550) × d ≤ 100000 nm ... Equation (3) Here, d represents the thickness of the liquid crystal layer B, and Δn(550) represents the refractive index anisotropy of the liquid crystal layer B at a wavelength of 550 nm, as described above.

[0061] By satisfying equation (2) or equation (3) above, the azimuthal angle dependence of the color of light emitted in an oblique direction can be further reduced.

[0062] From the viewpoint of further reducing the azimuthal angle dependence of the color of light emitted in an oblique direction, Δn(550)×d is more preferably 1600 nm or greater. Furthermore, from the viewpoint of further improving coating suitability, Δn(550)×d is more preferably 3000 nm or less, and even more preferably 2000 nm or less.

[0063] The thickness of liquid crystal layer B is not particularly limited, but from the viewpoint of thinning, it is preferably 30 μm or less, more preferably 25 μm or less, and even more preferably 20 μm or less. Furthermore, from the viewpoint of reducing the azimuthal angle dependence of the color of light emitted in an oblique direction, it is preferably 3 μm or more, more preferably 4 μm or more, even more preferably 8 μm or more, and particularly preferably 10 μm or more. Note that the thickness of liquid crystal layer B refers to the average thickness of liquid crystal layer B. The average thickness of liquid crystal layer B is obtained by measuring the thickness at five or more arbitrary points on liquid crystal layer B and taking the arithmetic mean of them. The thickness of liquid crystal layer B can also be measured using a micro-spectroscopic film thickness system (OPTM, manufactured by Otsuka Electronics Co., Ltd.).

[0064] <Method for forming liquid crystal layer B> The method for forming liquid crystal layer B is not particularly limited and known methods can be used. For example, a liquid crystal composition containing a disc-shaped liquid crystal compound can be applied to a predetermined support (including a temporary substrate) to form a coating film, and the resulting coating film can be cured (irradiated with ultraviolet light (photoirradiation treatment) or heat treatment) to fix the disc-shaped liquid crystal compound and produce liquid crystal layer B. If necessary, an alignment layer, as described later, may also be used.

[0065] The liquid crystal composition for forming the liquid crystal layer B, which includes a disc-shaped liquid crystal compound, may also contain components other than the disc-shaped liquid crystal compound described above. For example, the liquid crystal composition may contain a chiral agent for twisting and aligning the disc-shaped liquid crystal compound, a polymerization initiator, a surfactant, a solvent, an alignment agent, an adhesion improver, a plasticizer, a polymer, and the like.

[0066] 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).

[0067] Furthermore, before curing the formed coating film, an orientation treatment may be performed to orient the disc-shaped 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.

[0068] The curing treatment method applied to the coating film on which the disc-shaped 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.

[0069] -Support- The support supports the liquid crystal layer B and the alignment film, which will be 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 liquid crystal layer B. To form a uniform liquid crystal layer B 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.

[0070] 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.

[0071] 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 liquid crystal layer B 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 and removed as needed after the liquid crystal layer B has been formed.

[0072] - Alignment Film - Due to the need to efficiently control the orientation of disc-shaped 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.

[0073] 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.

[0074] 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 and removed as needed after the liquid crystal layer B is formed.

[0075] In addition to the liquid crystal optical element and liquid crystal layer B described above, the dimming device of the present invention may also have a functional layer that provides various functions. Examples of functional layers include an ultraviolet cut film that cuts ultraviolet rays and an anti-reflective layer that suppresses reflection.

[0076] [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.

[0077] A specific example of the imaging device of the present invention is a digital camera. As shown in Figure 5, 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.

[0078] As described above, the dimming device 10 of the present invention has low azimuth angle dependence on the color of light emitted in an oblique direction. Therefore, when applied to an imaging device, it can suppress changes in color in the peripheral area of ​​the imaging unit where the influence of obliquely incident light is high.

[0079] 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.

[0080] Furthermore, in an imaging device, the dimming device may be configured to be able to move in and out of the optical path. Since a dimming 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.

[0081] [Near-eye display] The near-eye display of the present invention is a near-eye display that includes the dimming device of the present invention as described above.

[0082] 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.

[0083] 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.

[0084] 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 a decrease in image visibility.

[0085] 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.

[0086] As described above, the dimming device 10 of the present invention has low azimuth angle dependence on the color of light emitted in an oblique direction. Therefore, when applied to a near-eye display, it can suppress the change in background color in each area of ​​the field of view perceived by the user wearing the near-eye display.

[0087] The present invention will be described in more detail below based on examples. The materials, amounts used, proportions, processing content, and processing procedures shown in the following examples can be modified as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the examples shown below.

[0088] [Example 1] [Preparation of Optical Laminate 1] <Preparation of Core Layer Cellulose Acrylate Dope 1> The following components were added to a mixing tank and stirred to dissolve each component, thereby preparing Core Layer Cellulose Acrylate Dope 1.

[0089] -------------------------------------------------- Core layer cellulose acetate dope 1 -------------------------------------------------- 100 parts by mass of cellulose acetate with acetyl substitution degree 2.88 12 parts by mass of the polyester below 4 parts by mass of the durability improver below 430 parts by mass of methylene chloride (first solvent) 64 parts by mass of methanol (second solvent) --------------------------------------------------

[0090] Polyester (number average molecular weight: 800)

[0091] Durability enhancer

[0092] <Preparation of outer layer cellulose acylate dope 1> To 90 parts by mass of the core layer cellulose acylate dope 1 described above, 10 parts by mass of the following mat agent dispersion 1 was added to prepare the outer layer cellulose acylate dope 1.

[0093] -------------------------------------------------- Mat agent dispersion 1 -------------------------------------------------- Silica particles with an average particle size of 20 nm (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.) 2 parts by mass Methylene chloride (first solvent) 76 parts by mass Methanol (second solvent) 11 parts by mass Core layer cellulose acylate dope 1 1 part by mass --------------------------------------------------

[0094] <Preparation of Cellulose Acrylate Film 1 (Support)> The core layer cellulose acylate dope 1 and the outer layer cellulose acylate dope 1 were filtered using filter paper with an average pore size of 34 μm and a sintered metal filter with an average pore size of 10 μm. Then, using a band casting machine, the core layer cellulose acylate dope 1 and the outer layer cellulose acylate dope 1 on both sides were cast simultaneously in three layers from the casting port onto a drum at 20°C.

[0095] Next, the film was peeled off the drum when its solvent content was approximately 20% by mass. The obtained film was fixed at both ends in the width direction with tenter clips, and the film was dried while being stretched to 1.1 times its width in the width direction, with a solvent content of 3 to 15% by mass.

[0096] Subsequently, the obtained film was further dried by transporting it between rolls in a heat treatment apparatus to produce a cellulose acylate film 1 with a thickness of 40 μm. The phase difference of the cellulose acylate film 1 was measured, and the results were Re(550) = 1 nm and Rth(550) = -5 nm.

[0097] <Preparation of Photo-Alignment Film Composition 1> A photo-alignment film composition 1 with the following composition was prepared.

[0098] ------------------------------------------------------------------- Composition 1 for photoalignment film ------------------------------------------------------------------- ・100 parts by mass of the following copolymer C1 ・3.57 parts by mass of the following thermal acid generator D1 ・0.36 parts by mass of the following stabilizer DIPEA ・714 parts by mass of butyl acetate ・476 parts by mass of methyl ethyl ketone -------------------------------------------------------------------

[0099] Copolymer C1 (weight average molecular weight: 40,000)

[0100] Thermal acid generator D1

[0101] Stabilizer DIPEA

[0102] <Preparation of Composition 1 for Forming Liquid Crystal Layer B> Composition 1 for forming liquid crystal layer B was prepared with the following composition.

[0103] ------------------------------------------------------------------- Composition 1 for forming liquid crystal layer B ------------------------------------------------------------------- ・Disc-shaped liquid crystal compound D1 below 100.00 parts by mass ・Photopolymerization initiator S1 below 3.00 parts by mass ・Surfactant P1 below 0.18 parts by mass ・Right-hand twist chiral agent C1 below 0.026 parts by mass ・Orientation film interface orientation agent below 1.00 parts by mass ・Cyclopentanone 179.67 parts by mass ・Methyl ethyl ketone 53.67 parts by mass -------------------------------------------------------------------

[0104] Disc-shaped liquid crystal compound D1

[0105] Photopolymerization initiator S1

[0106] Surfactant P1 [The numbers in the following formula indicate the content (mass%) of each repeating unit relative to the total repeating units in surfactant P1.] [Weight-average molecular weight Mw 20,000]

[0107] Right-handed chiral agent C1

[0108] Orientation film interface orientation agent

[0109] <Preparation of Photo-Alignment Film 1> The previously prepared photo-alignment film composition 1 was continuously applied to one side of the fabricated cellulose acylate film 1 (support) using a bar coater. After application, the solvent was removed by drying in a 120°C heating zone for 1 minute to form a photo-isomerized composition layer with a thickness of 0.3 μm.

[0110] Next, while wrapping it onto a mirror-finish backup roll, polarized ultraviolet light is irradiated (10 mJ / cm²). ２ The photo-alignment film 1 was formed by using an ultra-high pressure mercury lamp.

[0111] <Preparation of Liquid Crystal Layer B1> The previously prepared liquid crystal layer B-forming composition 1 was applied to the formed photo-alignment film 1 using a bar coater to form a composition layer. The temperature of the coating chamber was set to 23°C. The formed composition layer was heated to 110°C in a heating zone and then cooled to 50°C. Thereafter, while maintaining the temperature, it was irradiated with ultraviolet light (300 mJ / cm²) under a nitrogen atmosphere (oxygen concentration 100 ppm). ２ By using an ultra-high pressure mercury lamp, the orientation was fixed, and a liquid crystal layer B1 with a thickness d of 13.0 μm was fabricated, obtaining an optical laminate 1 (composition: liquid crystal layer B1 / photo-alignment film 1 / cellulose acylate film 1).

[0112] In the optical laminate 1, the liquid crystal layer B1 was bonded to the adhesive-backed glass, and then peeled off to transfer only the liquid crystal layer B1 onto the glass. The optical properties of the liquid crystal layer B1 were then determined using AxoScan from Axometrics and its analysis software (Multi-Layer Analysis). The product of the in-plane refractive index difference Δn(550) and thickness d of the liquid crystal layer B1 at a wavelength of 550 nm, n1(550), was 1627 nm, and the product of Δn(400) and thickness d at a wavelength of 400 nm, n1(400), was 2135 nm. Therefore, n1(400) / n1(550) = Δn(400) / Δn(550) was 1.31. The torsion angle of the liquid crystal compound was 90°, and the orientation axis angle of the liquid crystal compound with respect to the longitudinal direction of the long length was 0° on the surface side of the optical laminate 1 and 90° on the photo-alignment film 1 side.

[0113] [Fabrication of Guest Host Dimming Device 1] The following liquid crystal optical elements were used as the first and second liquid crystal optical elements. The liquid crystal optical elements were vertically aligned nematic (VAN) guest host cells with a cell spacing of 9.0 μm and a pre-tilt angle of 87° with respect to the orientation 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 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.

[0114] The optical laminate 1 prepared above (composition: liquid crystal layer B1 / photo-alignment film 1 / cellulose acylate film 1) was bonded to the first liquid crystal optical element with adhesive, with the liquid crystal layer B1 side facing the direction in which the guest material of the first liquid crystal optical element is tilted, so that the angle of the molecular axis on the surface side of liquid crystal layer B1 is 0° with respect to the direction in which the guest material of the first liquid crystal optical element is tilted (composition: first liquid crystal optical element / liquid crystal layer B1 / photo-alignment film 1 / cellulose acylate film 1). Subsequently, the laminate of photo-alignment film 1 and cellulose acylate film 1 was peeled off (composition: first liquid crystal optical element / liquid crystal layer B1). Next, a second liquid crystal optical element was attached to the liquid crystal layer B1 side using an adhesive such that the orientation of the guest material of the second liquid crystal optical element was 180° with respect to the orientation of the guest material of the first liquid crystal optical element, thereby fabricating a guest-host dimming device 1 (configuration: first liquid crystal optical element (orientation orientation 0°) / liquid crystal layer B1 (molecular axis orientation twisted from 0° to 90°) / second liquid crystal optical element (orientation orientation 180°)).

[0115] [Examples 2-5] In Examples 2-5, liquid crystal layers B2-5 and guest host dimming devices 2-5 were manufactured in the same manner as in Example 1, except that the mass of the right-twist chiral agent C1 contained in the liquid crystal layer B forming composition 1, the thickness of the liquid crystal layer B, and the twist angle were changed to the values ​​shown in Table 1 below.

[0116] Furthermore, the optical properties of liquid crystal layers B2 to B5 were determined using the same method as in Example 1. The results are shown in Table 1 below.

[0117] [Example 6] A liquid crystal layer B6 was fabricated in the same manner as in Example 1, except that the liquid crystal layer B thickness was set to 8.5 μm using the liquid crystal layer B formation composition 2 described below instead of liquid crystal layer B formation composition 1, and a guest host dimming device 6 was fabricated.

[0118] <Preparation of Composition 2 for Forming Liquid Crystal Layer B> Composition 2 for forming liquid crystal layer B was prepared with the following composition.

[0119] --------------------------------------------------- Composition 2 for forming liquid crystal layer B ------------------------------------------------------------------- ・Disc-shaped liquid crystal compound D2 below 100.00 parts by mass ・Photopolymerization initiator S1 above 3.00 parts by mass ・Surfactant P1 above 0.18 parts by mass ・Right-hand twist chiral agent C1 above 0.039 parts by mass ・Orientation film interface orientation agent above 1.00 parts by mass ・Cyclopentanone 179.67 parts by mass ・Methyl ethyl ketone 53.67 parts by mass -------------------------------------------------------------------

[0120] Disc-shaped liquid crystal compound D2

[0121] [Comparative Example 1] A λ / 4 plate cycloolefin polymer film (Re(550) = 275 nm, Re(400) / Re(550) = 1.0, manufactured by JSR Corporation) was bonded to the first liquid crystal optical element with adhesive such that the slow axis angle of the cycloolefin polymer film was 45° with respect to the orientation direction in which the guest material of the first liquid crystal optical element tilted (configuration: first liquid crystal optical element / cycloolefin polymer film). Next, a second liquid crystal optical element was bonded to the cycloolefin polymer film side with adhesive such that the orientation direction in which the guest material of the second liquid crystal optical element tilted was 180° with respect to the orientation direction in which the guest material of the first liquid crystal optical element tilted, thereby fabricating the guest host dimming device of Comparative Example 1 (configuration: first liquid crystal optical element (orientation direction 0°) / cycloolefin polymer film (slow axis orientation 45°) / second liquid crystal optical element (orientation direction 180°)).

[0122] [Evaluation] <Color change in oblique view> For the guest-host dimmers of Examples 1 to 6 and Comparative Example 1, light was incident from the first liquid crystal optical element side using a D65 light source, and a voltage was applied so that the transmittance to the normal incident light was 4%. Observations were made from the second liquid crystal optical element side on the output side at an extreme angle of 60° and azimuth angles of 0°, 45°, 90°, 135°, 225°, 270°, and 315°, and the color change in the oblique view was evaluated using the following index. The normal direction of the guest-host dimmer is set to an extreme angle of 0°, and the direction in which the guest material of the first liquid crystal optical element in the guest-host dimmer is tilted is set to an azimuth angle of 0°. The results are shown in Table 1.

[0123] (Evaluation Criteria) AAA: Very little variation in color between observation locations. A: Little variation in color between observation locations. B: Slight variation in color between observation locations. C: Very large variation in color between observation locations.

[0124]

[0125] Table 1 shows that the dimming device of the present invention exhibits less azimuth angle dependence on the color of light emitted in an oblique direction compared to the comparative example.

[0126] Furthermore, from a comparison of Examples 1 to 3, it can be seen that the Δn(550)×d of the liquid crystal layer B is preferably 1000 nm or more, and more preferably 1500 nm or more.

[0127] Furthermore, from a comparison of Examples 2 and 6, it can be seen that the Δn(400) / Δn(550) of the liquid crystal layer B is preferably 1.20 ≤ Δn(400) / Δn(550) ≤ 4.85.

[0128] The effects of the present invention are clear from the results above.

[0129] 10a Light control device 12 First liquid crystal optical element 14 Second liquid crystal optical element 18 Liquid crystal layer B 22 Disc-shaped liquid crystal compound 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 at least one liquid crystal layer B is included between the first liquid crystal optical element and the second liquid crystal optical element, wherein the liquid crystal layer B is a layer in which a disc-shaped liquid crystal compound is fixed, which is twisted and oriented at 80° to 100° with the thickness direction as the helical axis.

2. The dimming device according to claim 1, wherein the liquid crystal layer B satisfies the following equation: 1000 nm ≤ Δn(550) × d ≤ 100000 nm, where Δn(X) represents the refractive index anisotropy of the liquid crystal layer B at a wavelength of X nm, and d represents the thickness of the liquid crystal layer B.

3. The dimming device according to claim 1, wherein the liquid crystal layer B satisfies the following equation: 1500 nm ≤ Δn(550) × d ≤ 100000 nm, where Δn(X) represents the refractive index anisotropy of the liquid crystal layer B at a wavelength of X nm, and d represents the thickness of the liquid crystal layer B.

4. The dimming device according to claim 1, wherein the liquid crystal layer B satisfies the following equation: 1.20 ≤ Δn(400) / Δn(550) ≤ 4.85, where Δn(X) represents the refractive index anisotropy of the liquid crystal layer B at a wavelength of X nm.

5. The light control device according to claim 1, wherein the guest material is a dichroic dye molecule.

6. An imaging apparatus including a dimming device according to any one of claims 1 to 5.

7. A near-eye display comprising a dimming device according to any one of claims 1 to 5.

Images