Light control sheet and light control module

Abstract

Provided are a light control sheet and a light control module that can meet high quality requirements and diverse application needs. A light control sheet (10) has a light control layer (20) and a pair of base material layers (40X, 40Y) positioned on both sides of the light control layer (20). The light control sheet (10) is switched between a transparent state and an opaque state by switching between an energized state and a non-energized state of the light control layer (20). In a light control sheet (20), at least one of the pair of base material layers (40X, 40Y) satisfies conditional expressions (1), (2), and (3) and at least one of conditional expressions (4) and (5) among conditional expressions (1), (2), (3), (4), and (5) for meeting high quality requirements and diverse application needs.

Description

Dimming Sheet and Dimming Module

[0006] ,

[0001] The present invention relates to a dimming sheet and a dimming module.

[0002] Patent Document 1 describes a dimming sheet including a dimming layer containing a liquid crystal composition, a first transparent electrode layer and a second transparent electrode layer which are a pair of transparent electrode layers sandwiching the dimming layer, and a pair of transparent support layers sandwiching the dimming layer and the pair of transparent electrode layers. The first transparent electrode layer has an electrode portion configured to be applied with a driving voltage and an insulating portion. The insulating portion is adjacent to the electrode portion in a direction along the surface of the dimming sheet and extends along the outer edge of the electrode portion in a plan view as viewed from a position facing the surface of the dimming sheet.

[0003] WO2020 / 059820A1

[0004] However, according to the intensive research of the present inventor, the prior art including the dimming sheet of Patent Document 1 has room for improvement from the viewpoint of meeting high demand qualities and various application uses. Examples of being unable to meet high demand qualities include the occurrence of interference fringes (Newton rings, oblique interference fringes) when non-polarized light such as sunlight is transmitted in the transparent state of the dimming sheet, or the occurrence of color unevenness (e.g., rainbow unevenness) throughout the dimming sheet. Examples of being unable to meet various application uses include the inability to meet the demand qualities of in-vehicle applications that are more stringent than those of building material applications, or the inability to meet the demand qualities of new application uses that will be more stringent than in-vehicle applications in the future.

[0005] The present invention has been made in view of the above problems, and an object thereof is to provide a dimming sheet and a dimming module capable of meeting high demand qualities and various application uses.

[0006] The dimming sheet of this embodiment has a dimming layer and a pair of substrate layers located on both sides of the dimming layer, and is a dimming sheet that switches between a transparent state and an opaque state by switching between energized and unenhanced states of the dimming layer, characterized in that at least one of the pair of substrate layers satisfies conditional expressions (1), (2), and (3), and at least one of conditional expressions (4) and (5). (1) 7000 ≤ Re1(0°) (2) Rth1 ≤ 5000 (3) 0.1 ≤ Nz1 ≤ 0.5 (4) 100 ≤ |Re2(0°) - Re2(50°)| ≤ 500 (5) 5 ≤ |Re3(0°) - Re3(50°)| ≤ 1800 where, Re1(0°) = (nx1 - ny1) × d, Rth1 = (nx1 - nz1) × d Nz1 = Rth1 / Re1(0°) Re2(0°) = (nx2(0°) - ny2(0°)) × d, Re2(50°) = (nx2(50°) - ny2(50°)) × d, Re3(0°) = (nx3(0°) - ny3(0°)) × d, Re3(50°) = (nx3(50°) - ny3(50°)) × d, nx1: refractive index in the slow phase axis direction of the substrate layer when light with a wavelength of 589 nm is incident on the substrate layer at an incident angle of 0° (the incident angle when the light is incident perpendicularly to the substrate layer is assumed to be 0°), ny1: refractive index in the fast phase axis direction of the substrate layer when light with a wavelength of 589 nm is incident on the substrate layer at an incident angle of 0° (the incident angle when the light is incident perpendicularly to the substrate layer is assumed to be 0°), nz1: refractive index in the thickness direction of the substrate layer when light with a wavelength of 589 nm is incident on the substrate layer at an incident angle of 0° (the incident angle when the light is incident perpendicularly to the substrate layer is assumed to be 0°), nx2(0°): The refractive index in the substrate layer in the slow phase axis direction when light with a wavelength of 550 nm is incident on the substrate layer at an incident angle of 0° (the incident angle when incident perpendicularly to the substrate layer is assumed to be 0°), ny2(0°): The refractive index in the substrate layer in the fast phase axis direction when light with a wavelength of 550 nm is incident on the substrate layer at an incident angle of 0° (the incident angle when incident perpendicularly to the substrate layer is assumed to be 0°), nx2(50°): The refractive index in the substrate layer in the slow phase axis direction when light with a wavelength of 550 nm is incident on the substrate layer at an incident angle of 50° (the incident angle when incident perpendicularly to the substrate layer is assumed to be 0°),ny2(50°): The refractive index in the substrate layer in the phase-advancing axis direction when light with a wavelength of 550 nm is incident on the substrate layer at an incident angle of 50° (the incident angle when the light is incident perpendicularly to the substrate layer is set to 0°), nx3(0°): The refractive index in the substrate layer in the phase-lagging axis direction when light of a specific wavelength within the range of 360 nm to 830 nm is incident on the substrate layer at an incident angle of 0° (the incident angle when the light is incident perpendicularly to the substrate layer is set to 0°), ny3(0°): The refractive index in the substrate layer in the phase-advancing axis direction when light of a specific wavelength within the range of 360 nm to 830 nm is incident on the substrate layer at an incident angle of 0° (the incident angle when the light is incident perpendicularly to the substrate layer is set to 0°), nx3(50°): The refractive index in the substrate layer in the phase-lagging axis direction when light of a specific wavelength within the range of 360 nm to 830 nm is incident on the substrate layer at an incident angle of 50° (the incident angle when the light is incident perpendicularly to the substrate layer is set to 0°), ny3(50°): The refractive index in the phase-advancing axis direction of the substrate layer when light of a specific wavelength within the range of 360 nm to 830 nm is incident on the substrate layer at an incident angle of 50° (the incident angle when the light is incident perpendicularly to the substrate layer is defined as 0°). d: The thickness of the substrate layer (nm).

[0007] According to the present invention, it is possible to provide dimmable sheets and dimmable modules that can meet high quality requirements and various application applications.

[0008] This figure shows an example of the configuration of a dimming module. This figure shows an example of the configuration of a dimming sheet. This figure shows the difference in the orientation of liquid crystal molecules in the opaque state when not energized and the transparent state when energized of a normal type dimming sheet. This figure shows an example of the cross-sectional structure of a dimming layer containing a dichroic dye and a black spacer. This figure shows an example of the configuration of a reverse type dimming sheet. This figure shows experimental results to demonstrate the superiority of the dimming sheet of this embodiment.

[0009] <Definitions of Terms, etc.> In this specification, "light-transmitting member" may be read as "light-transmitting plate" or "light-transmitting window," and is used as a concept that includes "glass member," "glass plate," or "glass window." That is, in this specification, "glass member (glass plate, glass window)" is given as an example of a "light-transmitting member (light-transmitting plate, light-transmitting window)" for explanation, but a "light-transmitting member (light-transmitting plate, light-transmitting window)" may be composed of materials other than glass, various plastics, or other materials. For example, a "light-transmitting member (light-transmitting plate, light-transmitting window)" may be made of polycarbonate.

[0010] In this specification, a "dimming module" is defined as comprising a light-transmitting member and a dimming sheet attached to the light-transmitting member. The "light-transmitting member," as its name suggests, possesses the property of being light-transmitting. The "dimming sheet" is a component of the dimming module and may refer to the dimming sheet in its state before being attached to the light-transmitting member.

[0011] In this specification, a "dimming sheet" may have, as its basic structure, a dimming layer (for example, a polymer-dispersed liquid crystal layer), a pair of transparent conductive layers (conductive layers) located on both sides of the dimming layer, and a pair of transparent substrate layers (substrate layers) located on both sides of the pair of transparent conductive layers. A dimming sheet may be read as a dimming device or a dimming film.

[0012] In this specification, a "dimming sheet" ensures the light transmittance of the light-transmitting member and, consequently, the dimming module by not exhibiting its own dimming function (making it transparent), and inhibits the light transmittance of the light-transmitting member and, consequently, the dimming module by exhibiting its own dimming function (making it opaque). There are two types of dimming sheets: a normal type (normal mode) that is transparent when energized and opaque when not energized, and a reverse type (reverse mode) that is transparent when not energized and opaque when energized. Exercising the dimming function of a dimming sheet means when the normal type is not energized and when the reverse type is energized, and not exhibiting the dimming function of a dimming sheet may mean when the normal type is energized and when the reverse type is not energized. In this way, a dimming sheet can switch between a transparent state and an opaque state by switching between an energized state and an unenhanced state. Here, "transparent" does not mean a visible light transmittance of 100% (it does not mean a strictly transparent state), and "opaque" does not mean a visible light transmittance of 0% (it does not mean a strictly opaque state). Both terms are used to include a semi-transparent state.

[0013] In this specification, the dimming sheet may have a color tone of white when opaque (so-called white dimming) or a color tone of black when opaque (so-called black dimming).

[0014] In this specification, the dimming method using a dimming sheet may be, for example, a polymer dispersed liquid crystal (PDLC) method or a polymer network liquid crystal (PNLC) method. Alternatively, the dimming method using a dimming sheet may utilize electrochromic (EC), liquid crystal (LC), or suspended particle device (SPD).

[0015] In this specification, the light-transmitting member to which the dimming sheet is attached may include so-called single-piece or double-piece light-transmitting members. In the case of a single-piece light-transmitting member, the dimming sheet may be attached to the surface of the single-piece light-transmitting member. In the case of a double-piece light-transmitting member, the dimming sheet may be supported by sandwiching it between the two light-transmitting members with an intermediate layer (interlayer film), or the dimming sheet may be attached to the surface of one of the two light-transmitting members. Thus, there is a degree of freedom in the structure for attaching the dimming sheet to the light-transmitting member, and various design modifications are possible.

[0016] In this specification, "upper surface" and "lower surface" may be defined, for example, as the upper surface and the lower surface in the figure (or they may be defined based on the vertical direction in the figure). Also in this specification, "both sides" may be defined, regardless of the vertical direction in the figure, as being outside a certain reference (center) layer, whether directly or indirectly, or as a layer supported outside a certain reference (center) layer. For example, consider a laminated structure in which a reference (center) layer A is provided, layers B are provided on both sides of layer A, and layers C are provided on both sides of layer B. In this case, layer B is an "outer support layer" supported on "both sides" of layer A, and layer C is an "outer support layer" supported on "both sides" of layer A and layer B. In this sense, "both sides" and "outer support layer" may be read as "upper layer" and "upper support layer," in which case the further away from a certain reference (center) layer is defined as the upper layer, and the closer to a certain reference (center) layer is defined as the lower layer.

[0017] <Conventional Technical Challenges> Dimming devices (dimming sheets, dimming modules) have long been applied to building materials (e.g., window glass), and in recent years have been adopted for automotive applications (e.g., sunroofs and side windows), expanding their range of applications. New applications other than building materials and automotive applications are also being considered for dimming devices (dimming sheets, dimming modules), and market expansion is expected in the future.

[0018] However, according to the inventor's diligent research, the prior art, including the dimming sheet described in Patent Document 1, has room for improvement in terms of meeting high quality requirements and various application uses. Examples of failure to meet high quality requirements include the occurrence of interference fringes (Newton's rings, diagonal interference fringes) when unpolarized light such as sunlight is transmitted through the dimming sheet in its transparent state, or the occurrence of color unevenness (e.g., rainbow unevenness) throughout the dimming sheet. Examples of failure to meet various application uses include the inability to meet the stricter quality requirements of automotive applications than building material applications, or the inability to meet the stricter quality requirements of new applications in the future.

[0019] For example, a dimmable sheet (dimmable film) has a structure in which a PNLC layer (dimmable layer, liquid crystal layer) is sandwiched between transparent polymer film layers (transparent substrate layer, substrate layer). In this case, in transmission mode, the refractive index of the PNLC layer and the refractive index of the transparent polymer film layer are almost the same when viewed from the front, but there is a difference in refractive index when viewed from an oblique direction. Therefore, it is presumed that interference fringes are generated when light refracted at the interface between the upper and lower transparent polymer film layers interferes. In addition, since the transparent polymer film layer is flexible, there is variation within the plane, and light interference tends to occur even at the same interface.

[0020] Inserting polarizing plates could be considered as a countermeasure against color unevenness (for example, rainbow unevenness), but concerns exist regarding disadvantages such as an increase in the number of parts, increased structural complexity, reduced space efficiency, and higher costs associated with the insertion of polarizing plates.

[0021] <Technical Concept of the Invention> The inventors considered the above-mentioned problems as important technical challenges and, in order to realize a dimming sheet and dimming module that can meet high quality requirements and various application uses while guaranteeing (ensuring) the functionality of conventional polarizing plates, etc., they conducted research and development on parameters that a pair of substrate layers located on both sides of the dimming layer must satisfy, and have completed the present invention.

[0022] Here, "guaranteeing (ensuring) the function of conventional polarizers, etc." does not necessarily mean that it perfectly matches the effect obtained by optimally setting the parameters that the pair of substrate layers should satisfy in this embodiment (it is sufficient that it exhibits a certain level of interference fringe and color unevenness suppression effect, regardless of whether it is superior or inferior to conventional polarizers, etc.). In other words, while optimally setting the parameters that the pair of substrate layers should satisfy in this embodiment does not preclude the provision of additional components such as polarizers based on complementary purposes (reasons) or other purposes (reasons).

[0023] Polyethylene terephthalate (PET) is often used as the transparent polymer film (transparent substrate layer) for dimming devices (dimming sheets, dimming modules). However, PET films typically have birefringence, and when light passes through them, interference fringe-like color unevenness (e.g., rainbow unevenness) occurs. In this embodiment, while using a PET film as the dimming sheet (at least one of a pair of substrate layers), the parameters that the pair of substrate layers located on both sides of the dimming layer must satisfy are optimally set, thereby ensuring the functionality of conventional polarizers and meeting high quality requirements and various application applications.

[0024] In addition, as a high retardation substrate layer (transparent substrate layer), other materials besides the PET film mentioned above can be used, such as polypropylene film (PP), polyamide film (PA) made by thinly rolling out polyamide resin (nylon), and polyethylene naphthalate film (PEN). In this embodiment, even when these film materials are used as the light-adjusting sheet (at least one of a pair of substrate layers), by optimally setting the parameters that the pair of substrate layers located on both sides of the light-adjusting layer must satisfy, it is possible to meet high quality requirements and various application applications while guaranteeing (ensuring) the functionality of conventional polarizing plates, etc.

[0025] More specifically, the dimming sheet of this embodiment has a dimming layer and a pair of substrate layers located on both sides of the dimming layer, and switches between a transparent state and an opaque state by switching between energized and de-energized states of the dimming layer. At least one of the pair of substrate layers satisfies conditions (1), (2), and (3), and at least one of conditions (4) and (5). (1) 7000 ≤ Re1(0°) (2) Rth1 ≤ 5000 (3) 0.1 ≤ Nz1 ≤ 0.5 (4) 100 ≤ |Re2(0°) - Re2(50°)| ≤ 500 (5) 5 ≤ |Re3(0°) - Re3(50°)| ≤ 1800 where, Re1(0°) = (nx1 - ny1) × d, Rth1 = (nx1 - nz1) × d Nz1 = Rth1 / Re1(0°) Re2(0°) = (nx2(0°) - ny2(0°)) × d, Re2(50°) = (nx2(50°) - ny2(50°)) × d, Re3(0°) = (nx3(0°) - ny3(0°)) × d, Re3(50°) = (nx3(50°) - ny3(50°)) × d, nx1: Refractive index in the substrate layer in the slow axis direction when light with a wavelength of 589 nm is incident on the substrate layer at an incident angle of 0° (the incident angle when incident perpendicular to the substrate layer is assumed to be 0°), ny1: Refractive index in the substrate layer in the fast axis direction when light with a wavelength of 589 nm is incident on the substrate layer at an incident angle of 0° (the incident angle when incident perpendicular to the substrate layer is assumed to be 0°), nz1: Refractive index in the thickness direction of the substrate layer when light with a wavelength of 589 nm is incident on the substrate layer at an incident angle of 0° (the incident angle when incident perpendicular to the substrate layer is assumed to be 0°), nx2(0°): Refractive index in the substrate layer in the slow axis direction when light with a wavelength of 550 nm is incident on the substrate layer at an incident angle of 0° (the incident angle when incident perpendicular to the substrate layer is assumed to be 0°), ny2(0°): Refractive index in the substrate layer in the phase-advancing axis direction when light with a wavelength of 550 nm is incident on the substrate layer at an incident angle of 0° (the incident angle when incident perpendicularly to the substrate layer is assumed to be 0°), nx2(50°): Refractive index in the substrate layer in the phase-lagging axis direction when light with a wavelength of 550 nm is incident on the substrate layer at an incident angle of 50° (the incident angle when incident perpendicularly to the substrate layer is assumed to be 0°), ny2(50°): Refractive index in the substrate layer in the phase-advancing axis direction when light with a wavelength of 550 nm is incident on the substrate layer at an incident angle of 50° (the incident angle when incident perpendicularly to the substrate layer is assumed to be 0°),nx3(0°): Refractive index in the substrate layer in the slow phase axis direction when light of a specific wavelength within the range of 360 nm to 830 nm is incident on the substrate layer at an incident angle of 0° (incidence angle is 0° when incident perpendicular to the substrate layer), ny3(0°): Refractive index in the substrate layer in the fast phase axis direction when light of a specific wavelength within the range of 360 nm to 830 nm is incident on the substrate layer at an incident angle of 0° (incidence angle is 0° when incident perpendicular to the substrate layer), nx3(50°): Refractive index in the substrate layer in the slow phase axis direction when light of a specific wavelength within the range of 360 nm to 830 nm is incident on the substrate layer at an incident angle of 50° (incidence angle is 0° when incident perpendicular to the substrate layer), ny3(50°): Refractive index in the substrate layer in the fast phase axis direction when light of a specific wavelength within the range of 360 nm to 830 nm is incident on the substrate layer at an incident angle of 50° (incidence angle is 0° when incident perpendicular to the substrate layer), d: Thickness of the substrate layer (nm).

[0026] Even within the range that satisfies the above condition (1), it is preferable that the following conditions (1A) and (1B) are also satisfied. (1A) 7000 ≤ Re1(0°) ≤ 14000 (1B) 7000 ≤ Re1(0°) ≤ 13000

[0027] Even within the range that satisfies the above condition (2), it is preferable that the following conditions (2A), (2B), (2C), (2D), and (2E) are also satisfied. (2A) Rth1 ≤ 4000 (2B) 1500 ≤ Rth1 ≤ 5000 (2C) 1950 ≤ Rth1 ≤ 5000 (2D) 1500 ≤ Rth1 ≤ 4000 (2E) 1950 ≤ Rth1 ≤ 4000

[0028] Preferably, at least one of the pair of base layers satisfies all of the conditions (1), (2), (3), (4), and (5). Also, preferably, both of the pair of base layers satisfy all of the conditions (1), (2), (3), (4), and (5).

[0029] Furthermore, it is preferable that at least one (or both) of the pair of substrate layers satisfies condition (6) (preferably the thickness, or film thickness, is in the range of 120 μm to 200 μm). (6) 120000 ≤ d ≤ 200000

[0030] In conditional equation (1), "Re1 (0°)" may be interpreted as the retardation value (nm) when light with a wavelength of 589 nm is incident on the substrate layer at an incident angle of 0°, assuming that the incident angle when light is perpendicularly incident on the substrate layer is 0°.

[0031] In conditional equation (4), "Re2(0°)" may be interpreted as the retardation value (nm) when light with a wavelength of 550 nm is incident on the substrate layer at an incident angle of 0°, assuming the incident angle when light is perpendicular to the substrate layer is 0°. In conditional equation (4), "Re2(50°)" may be interpreted as the retardation value (nm) when light with a wavelength of 550 nm is incident on the substrate layer at an incident angle of 50°, assuming the incident angle when light is perpendicular to the substrate layer is 0°. The wavelength of 550 nm used in conditional equation (4) is based, for example, on the maximum human sensitivity at a certain brightness.

[0032] In condition (5), "Re3 (0°)" may be interpreted as the retardation value (nm) or its occupied range (nm) when light of a specific wavelength within the range of 360 nm to 830 nm is incident on the substrate layer at an incident angle of 0°, assuming the incident angle when light is perpendicularly incident on the substrate layer is 0°. In condition (5), "Re3 (50°)" may be interpreted as the retardation value (nm) or its occupied range (nm) when light of a specific wavelength within the range of 360 nm to 830 nm is incident on the substrate layer at an incident angle of 50°, assuming the incident angle when light is perpendicularly incident on the substrate layer is 0°. The wavelength range of 360 nm to 830 nm used in condition (5) is based on, for example, the wavelength range that can be perceived by the human eye.

[0033] Furthermore, the dimming sheet of this embodiment satisfies not only the retardation values ​​Re1, Re2, and Re3 defined in conditional equations (1), (4), and (5), but also "Rth1" in conditional equation (2) and "Nz1 (Rth1 / Re1 (0°))" in conditional equation (3), which define the retardation value in the thickness direction of the substrate layer (by using a substrate layer with high retardation in the transparent polymer film). This ensures the functionality of conventional polarizers and the like while meeting high quality requirements and various application applications. For example, it prevents interference fringes (Newton's rings, diagonal interference fringes) from occurring when unpolarized light such as sunlight is transmitted through the dimming sheet in its transparent state, and prevents color unevenness (e.g., rainbow unevenness) from occurring throughout the dimming sheet. Also, for example, it can clear the quality requirements of automotive applications which are stricter than those of building materials, and it can clear the quality requirements of new applications which may be stricter than those of automotive applications in the future.

[0034] If condition (1) is not satisfied, i.e., if Re1(0°) is less than 7000, it becomes difficult to meet high quality requirements and various application uses (it becomes impossible to completely suppress the occurrence of interference fringes and color unevenness). If condition (1A) is not satisfied, i.e., if Re1(0°) is greater than 14000, it becomes difficult to manufacture dimmable sheets.

[0035] If condition (2) is not satisfied, i.e., if Rth1 is greater than 5000, it becomes difficult to meet high quality requirements and various application uses (it becomes impossible to completely suppress the occurrence of interference fringes and color unevenness). If conditions (2B) and (2D) are not satisfied, i.e., if Rth1 is less than 1500, it becomes difficult to manufacture dimmable sheets.

[0036] If condition (3) is not satisfied, that is, if Nz1 is less than 0.1 or greater than 0.5, it becomes difficult to meet high quality requirements and various applications (it becomes impossible to completely suppress the occurrence of interference fringes and color unevenness), or it becomes difficult to manufacture dimmable sheets.

[0037] If condition (4) is not satisfied, that is, if |Re2(0°) - Re2(50°)| is less than 100 or greater than 500, it may become difficult to meet high quality requirements and various application uses (it may become impossible to completely suppress the occurrence of interference fringes and color unevenness), or it may become difficult to manufacture dimming sheets.

[0038] If condition (5) is not satisfied, that is, if |Re3(0°) - Re3(50°)| is less than 5 or greater than 1800, it may become difficult to meet high quality requirements and various applications (it may become impossible to completely suppress the occurrence of interference fringes and color unevenness), or it may become difficult to manufacture dimming sheets.

[0039] The interference fringes and color unevenness mentioned above are more noticeable (and detract from the aesthetics) in black-tinted film, where the color is black in the opaque state, than in white-tinted film, where the color is white in the opaque state. In addition, black is preferred for dimming sheets used in automobile sunroofs, and a good appearance is desired, such as when interference fringes and color unevenness caused by sunlight are not visible. For this reason, in a black-tinted dimming sheet containing at least one of a dichroic dye and a black spacer in the dimming layer, satisfying conditions (1), (2), and (3), and at least one of conditions (4) and (5), interference fringes and color unevenness can be removed more effectively (and the aesthetics can be improved).

[0040] Furthermore, by satisfying condition (6), the mechanical properties of the base layer are ensured while maintaining flexibility, making it less prone to tearing, ripping, etc., thus guaranteeing its practicality as an industrial material.

[0041] <Specific Embodiments> Embodiments will be described below with reference to the drawings. However, the drawings are schematic or conceptual, and the dimensions and proportions in each drawing are not necessarily the same as those in reality. Also, even when the same part is represented between drawings, the relationship of dimensions and proportions between them may be represented differently. In particular, the embodiments shown below are illustrative examples of devices and methods for realizing the technical concept of the present invention, and the technical concept of the present invention is not specified by the shape, structure, arrangement, etc. of the components. In the following description, elements having the same function and configuration will be denoted by the same reference numeral, and redundant explanations may be omitted.

[0042] Figure 1 shows an example of the configuration of a dimming module. Figure 2 shows an example of the configuration of a dimming sheet. As shown in Figure 1, a dimming module is constructed by attaching (sticking) a dimming sheet (dimming device, dimming film) 10 to a light-transmitting member (light-transmitting plate, light-transmitting window) 10X. The dimming sheet 10 may have an adhesive layer for attaching itself to the light-transmitting member 10X. Figure 2 also shows the structure including the drive mechanism (electrodes and wiring) of the dimming sheet 10.

[0043] The dimming sheet 10 has a dimming layer (liquid crystal layer) 20. The dimming layer 20 contains a liquid crystal composition. The dimming layer 20 may be composed of, for example, polymer dispersed liquid crystal (PDLC: Polymer Dispersed Liquid Crystal), polymer network liquid crystal (PNLC: Polymer Network Liquid Crystal), capsule-type nematic liquid crystal (NCAP: Nematic Curvilinear Aligned Phase), etc. For example, polymer dispersed liquid crystal and polymer network liquid crystal have a three-dimensional network-shaped polymer network and hold liquid crystal molecules in the voids of the polymer network. The liquid crystal molecules contained in the dimming layer 20 have, for example, a positive dielectric anisotropy, and the dielectric constant in the long axis direction of the liquid crystal molecules is larger than the dielectric constant in the short axis direction of the liquid crystal molecules. The liquid crystal molecules are, for example, Schiff base-based, azo-based, azoxy-based, biphenyl-based, terphenyl-based, benzoic acid ester-based, trans-based, pyrimidine-based, cyclohexanecarboxylic acid ester-based, phenylcyclohexane-based, dioxane-based liquid crystal molecules.

[0044] On the outside of one surface (the upper surface in the figure) of the dimming layer 20, a transparent conductive layer (conductive layer) 30X is provided, and on the outside of the transparent conductive layer 30X, a transparent base material layer (base material layer) 40X is provided. On the outside of the other surface (the lower surface in the figure) of the dimming layer 20, a transparent conductive layer (conductive layer) 30Y is provided, and on the outside of the transparent conductive layer 30Y, a transparent base material layer (base material layer) 40Y is provided. Thus, the dimming sheet 10 has the dimming layer 20, a pair of transparent conductive layers 30X and 30Y located on both sides sandwiching the dimming layer 20, and a pair of transparent base material layers 40X and 40Y located on both sides sandwiching the pair of transparent conductive layers 30X and 30Y.

[0045] The transparent conductive layers 30X and 30Y are transparent layers having conductivity. Examples of materials constituting the transparent conductive layers 30X and 30Y include, for example, indium tin oxide (ITO), fluorine-doped tin oxide (FTO), tin oxide, zinc oxide, carbon nanotubes (CNT), polymers containing poly(3,4-ethylenedioxythiophene) (PEDOT), multilayer films including Ag alloy thin films, and the like. The transparent substrate layers 40X and 40Y are layers formed by including materials such as polyethylene terephthalate (PET: Polyethylene Terephthalate).

[0046] In addition, as the "outer support layer" located outside the pair of transparent substrate layers 40X and 40Y, other additional / replacement layers may be provided. For example, as the "outer support layer", a layer for protecting the light control layer 20, the transparent conductive layers 30X and 30Y, and the transparent substrate layers 40X and 40Y, a layer that contributes to the control of light transmittance in the light control sheet 10, a layer that enhances characteristics such as the strength and heat resistance of the light control sheet 10, and the like may be used.

[0047] In the example of FIG. 1, the ends (end faces) of the light control sheet 10 are flush, and are aligned without shifting in the plan view. On the other hand, in the example of FIG. 2, the ends (end faces) of the light control sheet 10 are not flush, and are arranged so as to shift from each other in the plan view.

[0048] In the example of FIG. 2, when paying attention to the right end (right end face) of the light control sheet 10, the transparent conductive layer 30X and the transparent substrate layer 40X provided on one surface (the upper surface in the figure) of the light control layer 20 protrude to the right side of the light control layer 20. On the other hand, when paying attention to the left end (left end face) of the light control sheet 10, the transparent conductive layer 30Y and the transparent substrate layer 40Y provided on the other surface (the lower surface in the figure) of the light control layer 20 protrude to the left side of the light control layer 20.

[0049] An electrode portion 50X for applying a driving voltage to the dimming sheet 10 (dimming layer 20) is provided on the lower surface of the transparent conductive layer 30X that protrudes to the right of the dimming layer 20. An electrode portion 50Y for applying a driving voltage to the dimming sheet 10 (dimming layer 20) is provided on the upper surface of the transparent conductive layer 30Y that protrudes to the left of the dimming layer 20. A wiring portion 60X is connected to the electrode portion 50X, and a wiring portion 60Y is connected to the electrode portion 50Y, and the wiring portions 60X and 60Y are connected to the drive power supply 70. The wiring portions 60X and 60Y may be made of, for example, FPC (Flexible Printed Circuits).

[0050] As described above, when a drive current is passed through the transparent conductive layers 30X and 30Y via the electrode sections 50X and 50Y, the wiring sections 60X and 60Y, and the drive power supply 70, a drive voltage is applied between the transparent conductive layers 30X and 30Y, i.e., to the dimming layer 20.

[0051] When no driving voltage is applied between the transparent conductive layers 30X and 30Y (the dimming layer 20), the orientation of the liquid crystal molecules in the dimming layer 20 along its long axis is irregular. Therefore, light incident on the dimming layer 20 is scattered, and due to the synergistic effect of the dichroic dye and black spacer contained in the dimming layer 20, the dimming sheet 10 becomes black. In other words, the dimming sheet 10 is opaque. Alternatively, the dichroic dye and black spacer may be omitted from the dimming layer 20, making the dimming sheet 10 white (white dimming) when opaque.

[0052] On the other hand, when a driving voltage is applied between the transparent conductive layers 30X and 30Y (the dimming layer 20), the liquid crystal molecules of the dimming sheet 10 are oriented, and the long axis direction of the liquid crystal molecules is aligned with the electric field direction between the transparent conductive layers 30X and 30Y. As a result, light is more easily transmitted through the dimming layer 20, and the dimming sheet 10 becomes transparent. In this way, the dimming sheet 10 functions as a normal type (normal mode).

[0053] The dimming sheet 10 can be cut into a desired shape from a large sheet made of a multilayer structure comprising the layers that make up the dimming sheet 10, and used for various purposes. For example, the dimming sheet 10 can be used in various applications such as dimming films that block visibility from the inside and outside at specific times, office partitions, laminated glass, and frosted glass, where transparent glass is sufficient under normal circumstances. The dimming sheet 10 can also be installed in the upper part of a car's windshield to provide a partial sun visor function, or applied to car-mounted sunroofs and side windows.

[0054] Figures 3A and 3B show the difference in the orientation of liquid crystal molecules in the opaque state when the normal type of dimming sheet is not powered on (power off) and the transparent state when the power is on (power on).

[0055] As shown in Figure 3A, in the opaque state of the normal type dimming sheet 10 when it is not powered on (power off), the liquid crystal molecules located inside the dimming layer 20 are oriented unevenly, and because the refractive indices of the liquid crystal molecules and polymers do not match, a scattering state occurs, resulting in opacity. Moreover, the synergistic effect of the dichroic dye and black spacer (black functional fine particles) contained in the dimming layer 20 can guarantee black dimming in the opaque state of the dimming sheet 10.

[0056] As shown in Figure 3B, in the transparent state when the normal type dimming sheet 10 is powered on (power on), the liquid crystal molecules located inside the dimming layer 20 are balanced in orientation (their long axes are aligned in the left-right direction in the figure), and the refractive indices of the liquid crystal molecules and polymers match, resulting in transparency. Moreover, for example, the pair of transparent substrate layers 40X and 40Y located on both sides of the dimming layer 20 (on both sides of the pair of transparent conductive layers 30X and 30Y) satisfy the above-mentioned conditional equations (1) to (6), thereby meeting high quality requirements and various application applications (the occurrence of interference fringes and color unevenness can be suppressed).

[0057] Figure 4 shows an example of a cross-sectional structure of a photochromic layer containing a dichroic dye and a black spacer.

[0058] In Figure 4, each component included in the light-adjusting layer 20 is denoted by the following symbols: the transparent polymer layer is denoted by the symbol 20P, the voids by the symbol 20D, the liquid crystal composition by the symbol 20LC, the liquid crystal compound by the symbol LCM, the dichroic dye by the symbol DD, and the black spacer by the symbol SP. The light-adjusting layer 20 includes a transparent polymer layer 20P containing a plurality of voids 20D, a liquid crystal composition 20LC located within the voids 20D, and a black spacer SP. The liquid crystal composition 20LC contains a liquid crystal compound LCM and a dichroic dye DD.

[0059] The transparent polymer layer 20P may be a cured product of a photopolymerizable compound. The brightness of the dimming sheet 10 can be changed by changing the size of the voids 20D in the transparent polymer layer 20P. The light used to polymerize the photopolymerizable compound may be ultraviolet light or an electron beam. The photopolymerizable compound may be an ultraviolet polymerizable composition or an electron beam polymerizable composition. The liquid crystal composition 20LC may contain additives such as an antifoaming agent, an antioxidant, a weathering agent, a solvent, and a viscosity reducing agent. The weathering agent may be an ultraviolet absorber or a light stabilizer. The liquid crystal compound LCM may have positive dielectric anisotropy.

[0060] The black spacer SP may be dispersed throughout the transparent polymer layer 20P. The thickness of the black spacer SP may be determined by the thickness of the light-adjusting layer 20. The thickness of the black spacer SP may also be determined by the particle size of the black spacer SP. The black spacer SP may make the thickness of the light-adjusting layer 20 uniform. The black spacer SP may be a bead spacer or a photospacer formed by exposure and development of the photoresist. Preferably, the color of the black spacer SP is the same black as the color exhibited by the dichroic dye DD. For example, the outer surface of the black spacer SP may be black. Alternatively, the black spacer SP may have an outer surface and a central part covered by the outer surface, and the central part may be black. The black spacer SP may have a spherical shape or a columnar shape.

[0061] The dichroic dye DD may exhibit color (black) by being driven by a guest-host type with a liquid crystal compound LCM as the host. The dichroic dye DD may be at least one selected from the group consisting of, for example, polyiodine, azo compounds, anthraquinone compounds, naphthoquinone compounds, azomethine compounds, tetrazine compounds, quinophthalone compounds, merocyanine compounds, perylene compounds, and dioxazine compounds. The dichroic dye DD may be a single compound or a combination of two or more compounds. It is preferable that the dichroic dye DD exhibits black, which is the same color as the black spacer SP. The dichroic dye DD may exhibit black by being a single compound that exhibits black, or a combination of two or more compounds.

[0062] Figure 5 shows an example of the configuration of a reverse-type dimmable sheet. The normal-type dimmable sheet 10 shown in Figures 1 and 2 has a pair of transparent conductive layers 30X and 30Y interposed between the dimmable layer 20 and a pair of transparent substrate layers 40X and 40Y, which switch between a transparent state and an opaque state by switching between energized and de-energized states to the dimmable layer 20. The reverse-type dimmable sheet 10 shown in Figure 5 further has a pair of alignment layers 80X and 80Y interposed between the dimmable layer 20 and a pair of transparent conductive layers 30X and 30Y (the alignment layer 80X is located between the dimmable layer 20 and the transparent conductive layer 30X, and the alignment layer 80Y is located between the dimmable layer 20 and the transparent conductive layer 30Y).

[0063] The alignment layers 80X and 80Y are layers that control the orientation of liquid crystal molecules contained in the light-adjusting layer 20. When no driving voltage is applied, they align the liquid crystal molecules along the direction normal to the alignment layer. In a configuration with alignment layers 80X and 80Y, when a driving voltage is applied between the transparent conductive layers 30X and 30Y (light-adjusting layer 20), the light-adjusting sheet 10 becomes opaque, and when no driving voltage is applied between the transparent conductive layers 30X and 30Y (light-adjusting layer 20), the light-adjusting sheet 10 becomes transparent (functions as a reverse type (reverse mode)). Examples of materials constituting the alignment layers 80X and 80Y include organic compounds such as polyimide, polyamide, polyvinyl alcohol, and cyanide compounds, inorganic compounds such as silicon oxide and zirconium oxide, and silicon. Examples of orientation treatments for forming the alignment layers 80X and 80Y include rubbing treatment, polarized irradiation treatment, and microfabrication treatment.

[0064] Next, we will explain a method for manufacturing transparent substrate layers (substrate layers) 40X and 40Y that satisfy the above-mentioned conditions (1) to (6).

[0065] The transparent substrate layer can be composed of, for example, polyester such as polyethylene terephthalate or polyethylene naphthalate, polycarbonate, polystyrene, polyether ether ketone, polyphenylene sulfide, cycloolefin polymer, etc. These resins have excellent transparency as well as excellent thermal and mechanical properties, and have the advantage of being easy to control retardation by stretching (for example, uniaxial stretching in the longitudinal direction only, or biaxial stretching in the longitudinal and transverse directions). In particular, polyester, represented by polyethylene terephthalate, has a large intrinsic birefringence, and large retardation can be obtained relatively easily even with a thin film thickness, making it a suitable material.

[0066] Since the transparent substrate layer has a specific birefringence, it is desirable to use an oriented film, but the manufacturing method is not particularly limited as long as it satisfies the film characteristics defined in this embodiment, i.e., the above-described conditional equations (1) to (6).

[0067] In the first manufacturing embodiment, a transparent substrate layer material is melted and extruded into a sheet. This unoriented sheet is then stretched (uniaxially stretched) in only one direction (longitudinal direction) at a temperature above the glass transition temperature to obtain an oriented film having a specific retardation. Commercially available unoriented sheets or those produced by solution film formation can be suitably used. In the first manufacturing embodiment, by optimally setting various parameters such as the stretching (uniaxial stretching) temperature, stretching (uniaxial stretching) ratio, and sheet thickness, a transparent substrate layer satisfying the above-described conditional equations (1) to (6) can be manufactured.

[0068] In the second manufacturing method, the material for the transparent substrate layer is melted and extruded into a sheet. The resulting unoriented sheet is then transversely stretched in a tenter at a temperature above the glass transition temperature and subsequently heat-treated. In the second manufacturing method, by optimally setting various parameters such as the transverse stretching temperature, transverse stretching ratio, heat treatment temperature, heat treatment time, and sheet thickness, a transparent substrate layer satisfying the above-described conditions (1) to (6) can be manufactured.

[0069] In the third manufacturing embodiment, a jumbo roll (intermediate product) manufacturing process and a product roll manufacturing process may be performed. In the jumbo roll (intermediate product) manufacturing process, for example, PET pellets are melted in an extrusion hopper, a film shape is created using a die, longitudinal stretching is performed using a roll step, transverse stretching is performed by pulling the film with a chuck, and winding is performed using a winder. In the product roll manufacturing process, the jumbo roll (intermediate product) is slit to produce the final roll. In the third manufacturing embodiment, by optimally setting various parameters such as longitudinal stretching temperature, longitudinal stretching ratio, transverse stretching temperature, transverse stretching ratio, and film thickness, a transparent substrate layer that satisfies the above-described conditional equations (1) to (6) can be manufactured.

[0070] The transparent substrate layer may be surface-treated by known methods, such as corona discharge treatment (in air, nitrogen, carbon dioxide, etc.) or easy-adhesion treatment, in order to improve adhesion to adjacent layers such as adhesive layers, release layers, and antistatic layers, as well as water resistance and chemical resistance. Various known methods can be used for the easy-adhesion treatment, and methods such as applying various known easy-adhesion adhesives to the film during the film manufacturing process or to the film after stretching (uniaxial stretching) are preferably employed.

[0071] <Numerical Examples & Verification Experiments> The inventors conducted experiments to demonstrate the superiority of the dimming sheet 10 of this embodiment. The results are shown in Figure 6.

[0072] As shown in Figure 6, samples according to Examples 1-4 and Comparative Examples 1-5 of the present invention were prepared. The samples according to Examples 1-4 were prepared by uniaxial stretching (longitudinal stretching) (relatively high retardation PET), the samples according to Comparative Examples 1-4 were prepared by biaxial stretching (longitudinal and transverse stretching) (relatively low retardation PET), and the sample according to Comparative Example 5 was prepared by uniaxial stretching (longitudinal stretching) (relatively medium retardation PET). In each sample, the thickness (film thickness) d of the transparent substrate layer (substrate layer), as defined by conditional equation (6), was varied. For each sample, the retardation value was measured when parameters such as wavelength and incident angle were varied while the sample was transparent. Furthermore, the pair of transparent substrate layers (substrate layers) had the same shape and properties.

[0073] The retardation values, namely Re1 (0°) in condition (1), Rth1 in condition (2), Nz1 in condition (3), Re2 (0°) and Re2 (50°) in condition (4), and Re3 (0°) and Re3 (50°) in condition (5), were measured using a measuring device (RETS-100: product name) manufactured by Otsuka Electronics Co., Ltd. The measurement conditions were as follows: the retardation measurement range was based on the rotational analyzer method, the measurement spot diameter was φ5 mm, the tilt angle range was 0° or 50°, and the measurement wavelength was within the range of 360 nm to 830 nm (measurements were taken using sampling points at wavelengths of 360 nm, 450 nm, 550 nm, 589 nm, 650 nm, 750 nm, and 3830 nm).

[0074] The value d (thickness of the transparent substrate layer) in condition (6) was measured using a high-precision digital measuring instrument (Mitutoyo Lightmatic).

[0075] For each sample prepared, interference fringes and color unevenness (e.g., rainbow unevenness) were measured and evaluated. Specifically, under outdoor sunlight, the light-adjusting sheet was observed from the front and at an angle, with the sheet straight and slightly curved without bending, to confirm the occurrence of interference fringes and color unevenness. The specific evaluation criteria were set in the following three stages. For example, ○ may be evaluated as being within the acceptable range (acceptable product), × as being outside the acceptable range (unacceptable product), and △ may be evaluated as either within or outside the acceptable range. ○: No interference fringes or color unevenness are observed from any direction. △: Depending on the direction of observation, faint interference fringes or color unevenness are observed. ×: Depending on the direction of observation, interference fringes or color unevenness are clearly observed.

[0076] In Figure 6, areas that satisfy conditions (1) to (6) are depicted as clear areas without gray fill, while areas that do not satisfy conditions (1) to (6) are depicted with gray fill.

[0077] As shown in Figure 6, the samples according to Examples 1-4 satisfy all of the conditions (1) to (6) and are rated as within the acceptable range (acceptable product) (no interference fringes or color unevenness are observed when viewed from any direction).

[0078] On the other hand, samples from Comparative Examples 1-4, which do not satisfy most of the conditions (1) to (6), are rated × as outside the acceptable range (failed products) (obvious interference fringes and color unevenness are visible depending on the viewing direction). Furthermore, samples from Comparative Example 5, which satisfy conditions (2) to (5) but not conditions (1) and (6), are rated △, which falls between the acceptable range and outside the acceptable range (faint interference fringes and color unevenness are visible depending on the viewing direction).

[0079] Based on the above, the superiority of the samples according to Examples 1-4, which satisfy conditional equations (1) to (6), has been demonstrated.

[0080] Thus, the dimming sheet of this embodiment has a dimming layer and a pair of substrate layers located on both sides of the dimming layer, and is a dimming sheet that switches between a transparent state and an opaque state by switching between energized and de-energized states of the dimming layer, wherein at least one of the pair of substrate layers satisfies conditional equations (1), (2), and (3), and satisfies at least one of conditional equations (4) and (5). (1) 7000 ≤ Re1(0°) (2) Rth1 ≤ 5000 (3) 0.1 ≤ Nz1 ≤ 0.5 (4) 100 ≤ |Re2(0°) - Re2(50°)| ≤ 500 (5) 5 ≤ |Re3(0°) - Re3(50°)| ≤ 1800 where, Re1(0°) = (nx1 - ny1) × d, Rth1 = (nx1 - nz1) × d Nz1 = Rth1 / Re1(0°) Re2(0°) = (nx2(0°) - ny2(0°)) × d, Re2(50°) = (nx2(50°) - ny2(50°)) × d, Re3(0°) = (nx3(0°) - ny3(0°)) × d, Re3(50°) = (nx3(50°) - ny3(50°)) × d, nx1: refractive index in the slow phase axis direction of the substrate layer when light with a wavelength of 589 nm is incident on the substrate layer at an incident angle of 0° (the incident angle when the light is incident perpendicularly to the substrate layer is assumed to be 0°), ny1: refractive index in the fast phase axis direction of the substrate layer when light with a wavelength of 589 nm is incident on the substrate layer at an incident angle of 0° (the incident angle when the light is incident perpendicularly to the substrate layer is assumed to be 0°), nz1: refractive index in the thickness direction of the substrate layer when light with a wavelength of 589 nm is incident on the substrate layer at an incident angle of 0° (the incident angle when the light is incident perpendicularly to the substrate layer is assumed to be 0°), nx2(0°): The refractive index in the substrate layer in the slow phase axis direction when light with a wavelength of 550 nm is incident on the substrate layer at an incident angle of 0° (the incident angle when incident perpendicularly to the substrate layer is assumed to be 0°), ny2(0°): The refractive index in the substrate layer in the fast phase axis direction when light with a wavelength of 550 nm is incident on the substrate layer at an incident angle of 0° (the incident angle when incident perpendicularly to the substrate layer is assumed to be 0°), nx2(50°): The refractive index in the substrate layer in the slow phase axis direction when light with a wavelength of 550 nm is incident on the substrate layer at an incident angle of 50° (the incident angle when incident perpendicularly to the substrate layer is assumed to be 0°),ny2(50°): The refractive index in the substrate layer in the phase-advancing axis direction when light with a wavelength of 550 nm is incident on the substrate layer at an incident angle of 50° (the incident angle when the light is incident perpendicularly to the substrate layer is set to 0°), nx3(0°): The refractive index in the substrate layer in the phase-lagging axis direction when light of a specific wavelength within the range of 360 nm to 830 nm is incident on the substrate layer at an incident angle of 0° (the incident angle when the light is incident perpendicularly to the substrate layer is set to 0°), ny3(0°): The refractive index in the substrate layer in the phase-advancing axis direction when light of a specific wavelength within the range of 360 nm to 830 nm is incident on the substrate layer at an incident angle of 0° (the incident angle when the light is incident perpendicularly to the substrate layer is set to 0°), nx3(50°): The refractive index in the substrate layer in the phase-lagging axis direction when light of a specific wavelength within the range of 360 nm to 830 nm is incident on the substrate layer at an incident angle of 50° (the incident angle when the light is incident perpendicularly to the substrate layer is set to 0°), ny3(50°): The refractive index in the phase-advancing axis direction of the substrate layer when light of a specific wavelength within the range of 360 nm to 830 nm is incident on the substrate layer at an incident angle of 50° (the incident angle when the light is incident perpendicularly to the substrate layer is defined as 0°). d: The thickness of the substrate layer (nm).

[0081] This allows us to meet high quality requirements and various application applications while guaranteeing the functionality of conventional polarizing plates, etc. For example, it prevents interference fringes (Newton's rings, diagonal interference fringes) from occurring when unpolarized light such as sunlight is transmitted through the transparent state of the dimming sheet, and prevents color unevenness (e.g., rainbow unevenness) from occurring throughout the dimming sheet. Furthermore, it can meet the stricter quality requirements of automotive applications than building materials applications, and will be able to meet the stricter quality requirements of new applications in the future.

[0082] The present invention is not limited to the embodiments described above, and can be modified in various ways during implementation without departing from its essence. Furthermore, each embodiment may be combined as appropriate, and in that case, the combined effects can be obtained. Moreover, the above embodiments include various inventions, and various inventions can be extracted by selecting combinations from the multiple constituent elements disclosed. For example, if the problem can be solved and effects obtained even if some constituent elements are deleted from all the constituent elements shown in the embodiment, then the configuration with these deleted constituent elements can be extracted as an invention.

[0083] This application is based on Japanese Patent Application No. 2025-024955, filed on February 19, 2025. All of its contents are included herein.

Claims

1. A dimmable sheet having a dimmable layer and a pair of substrate layers located on both sides of the dimmable layer, wherein the dimmable sheet switches between a transparent state and an opaque state by switching between energized and unenerged states of the dimmable layer, characterized in that at least one of the pair of substrate layers satisfies conditional formulas (1), (2), and (3), and at least one of conditional formulas (4) and (5). (1) 7000 ≤ Re1(0°) (2) Rth1 ≤ 5000 (3) 0.1 ≤ Nz1 ≤ 0.5 (4) 100 ≤ |Re2(0°) - Re2(50°)| ≤ 500 (5) 5 ≤ |Re3(0°) - Re3(50°)| ≤ 1800 where, Re1(0°) = (nx1 - ny1) × d, Rth1 = (nx1 - nz1) × d Nz1 = Rth1 / Re1(0°) Re2(0°) = (nx2(0°) - ny2(0°)) × d, Re2(50°) = (nx2(50°) - ny2(50°)) × d, Re3(0°) = (nx3(0°) - ny3(0°)) × d, Re3(50°) = (nx3(50°) - ny3(50°)) × d, nx1: refractive index in the slow phase axis direction of the substrate layer when light with a wavelength of 589 nm is incident on the substrate layer at an incident angle of 0° (the incident angle when the light is incident perpendicularly to the substrate layer is assumed to be 0°), ny1: refractive index in the fast phase axis direction of the substrate layer when light with a wavelength of 589 nm is incident on the substrate layer at an incident angle of 0° (the incident angle when the light is incident perpendicularly to the substrate layer is assumed to be 0°), nz1: refractive index in the thickness direction of the substrate layer when light with a wavelength of 589 nm is incident on the substrate layer at an incident angle of 0° (the incident angle when the light is incident perpendicularly to the substrate layer is assumed to be 0°), nx2(0°): The refractive index in the substrate layer in the slow phase axis direction when light with a wavelength of 550 nm is incident on the substrate layer at an incident angle of 0° (the incident angle when incident perpendicularly to the substrate layer is assumed to be 0°), ny2(0°): The refractive index in the substrate layer in the fast phase axis direction when light with a wavelength of 550 nm is incident on the substrate layer at an incident angle of 0° (the incident angle when incident perpendicularly to the substrate layer is assumed to be 0°), nx2(50°): The refractive index in the substrate layer in the slow phase axis direction when light with a wavelength of 550 nm is incident on the substrate layer at an incident angle of 50° (the incident angle when incident perpendicularly to the substrate layer is assumed to be 0°),ny2(50°): The refractive index in the substrate layer in the phase-advancing axis direction when light with a wavelength of 550 nm is incident on the substrate layer at an incident angle of 50° (the incident angle when the light is incident perpendicularly to the substrate layer is set to 0°), nx3(0°): The refractive index in the substrate layer in the phase-lagging axis direction when light of a specific wavelength within the range of 360 nm to 830 nm is incident on the substrate layer at an incident angle of 0° (the incident angle when the light is incident perpendicularly to the substrate layer is set to 0°), ny3(0°): The refractive index in the substrate layer in the phase-advancing axis direction when light of a specific wavelength within the range of 360 nm to 830 nm is incident on the substrate layer at an incident angle of 0° (the incident angle when the light is incident perpendicularly to the substrate layer is set to 0°), nx3(50°): The refractive index in the substrate layer in the phase-lagging axis direction when light of a specific wavelength within the range of 360 nm to 830 nm is incident on the substrate layer at an incident angle of 50° (the incident angle when the light is incident perpendicularly to the substrate layer is set to 0°), ny3(50°): The refractive index in the phase-advancing axis direction of the substrate layer when light of a specific wavelength within the range of 360 nm to 830 nm is incident on the substrate layer at an incident angle of 50° (the incident angle when the light is incident perpendicularly to the substrate layer is defined as 0°). d: The thickness of the substrate layer (nm).

2. The dimming sheet according to claim 1, characterized in that at least one of the pair of substrate layers satisfies all of the following conditions: (1), (2), (3), (4), and (5).

3. The dimming sheet according to claim 1, characterized in that both of the pair of substrate layers satisfy all of the following conditions: (1), (2), (3), (4), and (5).

4. The dimming sheet according to claim 1, characterized in that at least one of the pair of substrate layers satisfies the condition (6). (6) 120000 ≤ d ≤ 200000 5. The light-adjusting sheet according to claim 1, characterized in that the light-adjusting layer includes at least one of a dichroic dye and a black spacer.

6. The light-adjusting sheet according to claim 1, characterized in that at least one of the pair of substrate layers is made of polyethylene terephthalate (PET).

7. The dimmable sheet according to claim 1, further comprising a pair of conductive layers interposed between the dimmable layer and the pair of substrate layers, which switch between a transparent state and an opaque state by switching between energized and de-energized states to the dimmable layer.

8. The dimming sheet according to claim 7, characterized in that it has a pair of orientation layers interposed between the dimming layer and the pair of conductive layers.

9. A dimming module characterized by being configured by attaching a dimming sheet according to any one of claims 1 to 8 to a light-transmitting member.

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