Light control device and light control module

Abstract

The purpose of the present invention is to provide a light control device and a light control module that make it possible to increase the transparency with fewer visibly cloudy areas, regardless of the angle of viewing, when the light control device is in a transparent state. A light control device (10) according to the present invention is characterized by comprising a light control layer (20) and outer support layers (30X, 30Y, 40X, 40Y) that are positioned on both sides of the light control layer, wherein: when the light control layer is energized via the outer support layers, the light control layer is in a transparent state; when the light control layer is not energized via the outer support layers, the light control layer is in an opaque state; the light control layer includes a dichroic dye (DD) and a black spacer (SP); the color in the opaque state is black; the haze within a viewing angle of 170° in the transparent state is 14% or less; and the film thickness of the light control layer is 12-25 μm.

Description

Dimming device and dimming module

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

[0002] Patent Document 1 describes a design material whose light transmission and scattering properties can be changed by applying an electric current. This design material includes a polymer-dispersed liquid crystal layer and a positive C-plate layer. The polymer-dispersed liquid crystal layer is formed by laminating a first substrate, a first transparent conductive layer, a polymer / liquid crystal composite layer, a second transparent conductive layer, and a second substrate in this order. The positive C-plate layer contains a dichroic dye and is provided on at least one side of the polymer-dispersed liquid crystal layer.

[0003] Conventional light-controlling devices (light-controlling sheets, light-controlling films) including the design material of Patent Document 1 guarantee translucency by not exerting their own light-controlling function (making them transparent), and inhibit translucency by exerting their own light-controlling function (making them opaque). Furthermore, as light-controlling devices (light-controlling sheets, light-controlling films), normal types (normal mode) that are transparent when energized and opaque when de-energized are known. Also, as light-controlling devices (light-controlling sheets, light-controlling films), reverse types (reverse mode) that are transparent when de-energized and opaque when energized are known.

[0004] Japanese Patent Application Laid-Open No. 2020-144261

[0005] However, according to the inventor's intensive research, there is room for improvement in that normal-type light control devices (light control sheets, light control films) have areas that appear cloudy when they are transparent when energized. In particular, when a normal-type light control device (light control sheet, light control film) is viewed from an angle, the number of areas that appear cloudy tends to increase. For this reason, for example, when a normal-type light control device (light control sheet, light control film) is applied to an automotive sunroof or side window, there is a concern that the transparency may change depending on the seat in the vehicle, making it visible.

[0006] Furthermore, reverse-type light control devices (light control sheets, light control films) have room for improvement in that some areas appear cloudy when they are in a transparent state when not energized. In particular, when reverse-type light control devices (light control sheets, light control films) are viewed obliquely, the number of areas that appear cloudy tends to increase. For this reason, for example, when reverse-type light control devices (light control sheets, light control films) are applied to vehicle sunroofs or side windows, there is a concern that the transparency may change depending on the seat in the vehicle, making the device visible.

[0007] The present invention was completed based on the above-mentioned problem awareness, and one of its objects is to provide a dimming device and dimming module that can increase transparency when viewed from any angle with few areas that appear cloudy when the normal-type dimming device is in a transparent state when powered on, and another object is to provide a dimming device and dimming module that can increase transparency when viewed from any angle with few areas that appear cloudy when the reverse-type dimming device is in a transparent state when powered off.

[0008] The dimming device of this embodiment has a dimming layer and outer support layers located on both sides of the dimming layer, and is characterized in that when current is passed through the dimming layer via the outer support layer, the dimming layer becomes transparent, and when current is not passed through the outer support layer, the dimming layer becomes opaque, the dimming layer contains a dichroic dye and a black spacer, has a black color in the opaque state, has a haze of 14% or less within a viewing angle of 170° in the transparent state, and has a film thickness of 12 μm or more and 25 μm or less.

[0009] The dimming device of this embodiment has a dimming layer and outer support layers located on both sides of the dimming layer, the dimming layer being transparent when no current is passed through the outer support layer, and being opaque when current is passed through the dimming layer through the outer support layer, the dimming layer containing a dichroic dye and a black spacer, being black in color in the opaque state, having a haze of 14% or less within a viewing angle of 170° in the transparent state, and having a film thickness of 15 μm or less.

[0010] According to the present invention, it is possible to provide a light control device and a light control module that can increase transparency when viewed from any angle with few areas that appear cloudy when the normal-type light control device is in a transparent state when power is applied. Also, it is possible to provide a light control device and a light control module that can increase transparency when viewed from any angle with few areas that appear cloudy when the reverse-type light control device is in a transparent state when power is not applied.

[0011] 1 is a first diagram showing an example of the configuration of a normal-type black dimming dimming device; FIG. 2 is a second diagram showing an example of the configuration of a normal-type black dimming dimming device; FIG. 3 is a diagram showing the difference in the orientation of liquid crystal molecules in a normal-type black dimming dimming device in an opaque state when not energized and in a transparent state when energized; FIG. 4 is an SEM image showing the cross-sectional structure of a dimming layer in a normal-type black dimming dimming device in a transparent state when energized; FIG. 5 is a diagram showing an example of the cross-sectional structure of a dimming layer including a dichroic dye and a black spacer; FIG. 6 is a diagram showing the results of an experiment to demonstrate the superiority of the dimming device of this embodiment (normal-type black dimming); FIG. 7 is a first diagram showing an example of the configuration of a reverse-type black dimming dimming device; FIG. 8 is a second diagram showing an example of the configuration of a reverse-type black dimming dimming device; FIG. 9 is a diagram showing the difference in the orientation of liquid crystal molecules in a transparent state when not energized and in an opaque state when energized; FIG. 10 is an SEM image showing the cross-sectional structure of a dimming layer in a reverse-type black dimming dimming device in a transparent state when not energized. 10A and 10B are diagrams showing the results of an experiment to demonstrate the superiority of the light control device (reverse type, black light control) of the present embodiment.

[0012] <Definitions of Terms, etc.> In this specification, the term "light-transmitting member" may be read as a "light-transmitting plate" or a "light-transmitting window," and is used as a concept including a "glass member," a "glass plate," or a "glass window." That is, in this specification, a "glass member (glass plate, glass window)" is described as an example of a "light-transmitting member (light-transmitting plate, light-transmitting window)," but the "light-transmitting member (light-transmitting plate, light-transmitting window)" may be made of materials other than glass, including various plastics and other materials. For example, the "light-transmitting member (light-transmitting plate, light-transmitting window)" may be made of polycarbonate.

[0013] In this specification, the term "dimming module" refers to a light-transmitting member and a dimming device attached to the light-transmitting member. The term "dimming device" may refer to a component of the light-transmitting module, namely, the dimming device in its state before being attached to the light-transmitting member. As the name suggests, the light-transmitting member has translucency as its own property.

[0014] In this specification, a normal-type light control device has, as its basic configuration, a light control layer (e.g., a polymer dispersed liquid crystal layer) and outer support layers (e.g., a pair of transparent conductive layers and a transparent substrate layer) located on both sides of the light control layer. The light control device may also be read as a light control sheet or a light control film.

[0015] In this specification, a reverse-type light control device has, as its basic configuration, a light control layer (e.g., a polymer-dispersed liquid crystal layer), a pair of alignment layers (e.g., organic compounds such as polyimide, polyamide, polyvinyl alcohol, cyanide compounds, etc., inorganic compounds such as silicon oxide and zirconium oxide, silicon, etc.) located on both sides of the light control layer, and outer support layers (e.g., pairs of transparent conductive layers and transparent substrate layers located on both sides of the pair of alignment layers) located on both sides of the pair of alignment layers. The light control device may also be read as a light control sheet or a light control film.

[0016] In this specification, a light-controlling device (light-control sheet, light-control film) guarantees light transmittance by not exerting its own light-controlling function (transparent), and inhibits light transmittance by exerting its own light-controlling function (opaque).

[0017] In this specification, in a normal-type light control device (light control sheet, light control film), the light control layer becomes transparent when current is passed through the outer support layer, and becomes opaque when current is not passed through the outer support layer. In other words, when the light control function of a light control device (light control sheet, light control film) is exhibited, it means that the light control function is not exhibited when current is passed through the normal type.

[0018] In this specification, in a reverse-type light control device (light control sheet, light control film), the light control layer is transparent when no current is applied to the light control layer via the outer support layer, and is opaque when current is applied to the light control layer via the outer support layer. In other words, when the light control function of a light control device (light control sheet, light control film) is exhibited, it means when current is applied in the reverse type, and when the light control function of a light control device (light control sheet, light control film) is not exhibited, it means when current is not applied in the reverse type.

[0019] In this way, the light control device (light control sheet, light control film) can be switched between a transparent state and an opaque state by switching between an energized state and an unenergized state. Here, the transparent state does not mean a visible light transmittance of 100% (does not mean a strict transparent state), and the opaque state does not mean a visible light transmittance of 0% (does not mean a strict opaque state), and both are used to mean a semi-transparent state.

[0020] In this specification, it is assumed that the light control device (light control sheet, light control film) has a black color in the opaque state (so-called black light control).

[0021] In this specification, the dimming method using the dimming device and dimming module is assumed to be a polymer dispersed liquid crystal (PDLC) method.

[0022] In this specification, the light-transmitting member to which the light control device (light control sheet, light control film) is attached may include so-called one-piece or two-piece light-transmitting members. In the case of a one-piece light-transmitting member, the light-controlling device (light control sheet, light control film) may be attached to the surface of the one-piece light-transmitting member. In the case of a two-piece light-transmitting member, the light-controlling device (light control sheet, light control film) may be sandwiched and supported by interposing an intermediate layer (intermediate film) between the two light-transmitting members, or the light-controlling device (light control sheet, light control film) may be attached to the surface of one of the two light-transmitting members. In this way, there is a degree of freedom in the structure for attaching the light-controlling device (light control sheet, light control film) to the light-transmitting member, and various design modifications are possible.

[0023] In this specification, the terms "upper surface" and "lower surface" may be defined as, for example, the upper and lower surfaces in a drawing (these may be defined based on the vertical direction in the drawing). Furthermore, in this specification, the terms "outside" and "outer support layer" may be defined as the outside of a certain reference (center) layer, or as a layer supported on the outside of the certain reference (center) layer, regardless of the vertical direction in the drawing. For example, consider a laminated structure in which a certain reference (center) layer A is provided, layer B is provided on both sides of layer A, and layer C is provided on both sides of layer B. In this case, layer B is an "outer support layer" supported on the "outside" of layer A, and layer C is an "outer support layer" supported on the "outside" of layers A and B. In this sense, "outside" and "outer support layer" may be read as "upper layer" and "upper support layer," and in this case, the further away from a certain reference (center) layer, the higher the layer is defined as the upper layer, and the closer to the certain reference (center) layer, the lower the layer is defined as the lower layer.

[0024] In this specification, "haze (value)" is sometimes called cloudiness value and is an index (value) indicating the degree of cloudiness (turbidity). The smaller the haze (value), the higher the transparency, and the larger the haze (value), the lower the transparency (cloudiness). The haze (value) can be calculated by (total luminous transmittance - parallel ray transmittance) / total luminous transmittance x 100 (%).

[0025] <Conventional Technical Issues> In recent years, the adoption of light-controlling films using polymer-dispersed liquid crystals has been increasing. These films are primarily used in building materials, such as window glass and partitions, to create a sense of space by opaquely controlling privacy and transparently controlling openness. They are also increasingly being applied to sunroofs and side windows in automobiles. For example, many light-controlling devices used in building materials have been designed to control the scattering of transmitted light by applying voltage, thereby altering transparency or opacity (the opaque state is white). However, in recent years, there has been a demand for devices that can control the opaque state between black and transparent (or semi-transparent) (so-called black light-controlling devices, where the opaque state is black) in consideration of environmental issues, solar radiation control (light blocking properties), and design features. Furthermore, for automotive applications, for example, there has been a growing demand for so-called reverse-type (reverse mode) light-controlling films, in which the light-controlling layer (e.g., the polymer-dispersed liquid crystal layer) is transparent when no current is applied and opaque when current is applied.

[0026] However, according to the inventor's intensive research, there is room for improvement in that normal-type light control devices (light control sheets, light control films) have areas that appear cloudy when they are transparent when energized. In particular, when a normal-type light control device (light control sheet, light control film) is viewed from an angle, the number of areas that appear cloudy tends to increase. For this reason, for example, when a normal-type light control device (light control sheet, light control film) is applied to an automotive sunroof or side window, there is a concern that the transparency may change depending on the seat in the vehicle, making it visible.

[0027] Furthermore, according to the inventor's intensive research, there is room for improvement in reverse-type light control devices (light control sheets, light control films) in that some areas appear cloudy when the device is not energized and transparent. In particular, when a reverse-type light control device (light control sheet, light control film) is viewed obliquely, the number of areas that appear cloudy tends to increase. For this reason, for example, if a reverse-type light control device (light control sheet, light control film) is applied to an automotive sunroof or side window, there is a concern that the transparency may change depending on the seat inside the vehicle, making it visible.

[0028] <Technical concept of the present invention / In the case of normal type / black dimming> The inventors have completed the present invention through research and development of a dimming device and dimming module that can increase transparency when viewed from any angle, with few areas that appear cloudy when the normal type dimming device is in a transparent state when powered on.

[0029] The present inventors investigated the reason why a transparent light control device (light control sheet, light control film) appears cloudy (whitening, high haze value) when viewed obliquely, and discovered the following: In light control devices (light control sheets, light control films) that use polymer-dispersed liquid crystals, due to their structure, when transparent, even if the liquid crystals are aligned, the transmitted light is not parallel to incident light from an oblique angle and is scattered, resulting in reduced transparency.

[0030] To solve (eliminate) the above technical problems (causes), the light control device (light control sheet, light control film) of this embodiment has the following configuration requirements. The light control device (light control sheet, light control film) of this embodiment has a light control layer and outer support layers located on both sides of the light control layer. The light control device (light control sheet, light control film) of this embodiment is a normal type (normal mode) in which the light control layer becomes transparent when current is applied to the light control layer through the outer support layer and becomes opaque when current is not applied to the light control layer through the outer support layer. The light control layer contains a dichroic dye (at least one type of dichroic dye) and a black spacer, and is black in color in the opaque state (so-called black light control). Furthermore, the haze within a viewing angle of 170° in the transparent state is 14% or less. Furthermore, the film thickness of the light control layer is 12 μm or more and 25 μm or less.

[0031] By incorporating a dichroic dye and black spacers into the light-control layer to make the color black in the opaque state (so-called black light-control), scattered light is absorbed and reduced, thereby reducing whitening due to scattered light when viewed from an angle, and the haze within a viewing angle of 170° in the transparent state can be reduced to 14% or less. This makes it possible to realize a light-control device (light-control sheet, light-control film) with a wide viewing angle that is suitable for, for example, the interior of a vehicle or a living space.

[0032] By including black spacers (black functional particles) in the photochromic layer, high functionality can be achieved in combination with the dichroic dye contained in the photochromic layer (due to the synergistic effect of the dichroic dye and the black spacers). More specifically, since scattered light is absorbed by the dichroic dye and the black spacers inside the photochromic layer, high light blocking properties can be achieved in the opaque state, and high visibility can be achieved in the transparent state (for example, a haze of 14% or less within a viewing angle of 170° in the transparent state).

[0033] The thickness of the photochromic layer is preferably 15 μm to 22 μm, within the range of 12 μm to 25 μm. The inventors have conducted extensive research to determine the optimal thickness for increasing transparency and minimizing areas that appear cloudy when viewed from any angle in a normal-type, black-light-adjusting photochromic device (photochromic sheet, photochromic film) that is transparent when energized. As a result, they have found that a thickness within the above range is preferable. If the photochromic layer thickness is less than 12 μm or more than 25 μm, there is a risk that the number of areas that appear cloudy when energized in a normal-type, black-light-adjusting photochromic device (photochromic sheet, photochromic film) that appears cloudy may increase.

[0034] The light control device (light control sheet, light control film) of this embodiment preferably has a haze of 5% or less within a viewing angle of 170° in the transparent state. This makes it possible to more significantly exhibit the effect of increasing transparency by reducing the number of areas that appear cloudy when viewed from any angle in the transparent state when a normal-type light control device (light control sheet, light control film) is energized.

[0035] The light control device (light control sheet, light control film) of this embodiment preferably has a total light transmittance of 40% or more in the transparent state and a total light transmittance of 20% or less in the opaque state, thereby achieving both the function of the light control device (light control sheet, light control film) in the transparent state (high visibility) and the function of the light control device (light control sheet, light control film) in the opaque state (high light blocking ability).

[0036] The light-controlling layer can be a polymer-dispersed liquid crystal layer, and the outer support layer can have a pair of transparent conductive layers positioned on either side of the light-controlling layer, and a pair of transparent substrate layers positioned on either side of the pair of transparent conductive layers.

[0037] <Specific Embodiments / Normal Type / Black Dimming> The following describes embodiments with reference to the drawings. However, the drawings are schematic or conceptual, and the dimensions and ratios of each drawing are not necessarily the same as those in reality. Furthermore, even when the same parts are shown between drawings, the dimensional relationships and ratios may be different. In particular, the embodiments shown below are examples of devices and methods for embodying the technical concept of the present invention, and the shape, structure, arrangement, etc. of the components do not specify the technical concept of the present invention. In the following description, elements having the same function and configuration are designated by the same reference numerals, and redundant description may be omitted.

[0038] 1 and 2 are first and second diagrams showing an example of the configuration of a normal-type, black-adjustable light control device (light control sheet, light control film) 10. FIG. 1 mainly illustrates the layered structure of the light control device 10, while FIG. 2 mainly illustrates the structure including the drive mechanism (electrodes and wiring) of the light control device 10. As shown in FIG. 1, the light control device 10 is attached (adhered) to a light-transmitting member (light-transmitting plate, light-transmitting window) designated by the reference numeral 10X when in use. In this case, the light control device 10 may have an adhesive layer for attaching itself to the light-transmitting member 10X. The light control module of this embodiment is configured by attaching the light control device 10 to the light-transmitting member 10X.

[0039] The light control device 10 has a light control layer (liquid crystal layer) 20. The light control layer 20 contains a liquid crystal composition. The light control layer 20 is assumed to be made of, for example, polymer dispersed liquid crystal (PDLC: Polymer Dispersed Liquid Crystal), but may also be made of polymer network liquid crystal (PNLC: Polymer Network Liquid Crystal), encapsulated nematic liquid crystal (NCAP: Nematic Curvilinear Aligned Phase), or the like. For example, polymer dispersed liquid crystal and polymer network liquid crystal have a polymer network with a three-dimensional mesh-like structure, and liquid crystal molecules are held in the voids of the polymer network. The liquid crystal molecules contained in the light control layer 20 have, for example, positive dielectric anisotropy, and the dielectric constant in the long axis direction of the liquid crystal molecules is greater than the dielectric constant in the short axis direction of the liquid crystal molecules. The liquid crystal molecules are, for example, Schiff base, azo, azoxy, biphenyl, terphenyl, benzoate, tolan, pyrimidine, cyclohexanecarboxylic acid ester, phenylcyclohexane, and dioxane liquid crystal molecules.

[0040] A transparent conductive layer 30X is provided on the outside of one surface (the top surface in the figure) of the photochromic layer 20, and a transparent substrate layer 40X is provided on the outside of the transparent conductive layer 30X. A transparent conductive layer 30Y is provided on the outside of the other surface (the bottom surface in the figure) of the photochromic layer 20, and a transparent substrate layer 40Y is provided on the outside of the transparent conductive layer 30Y. As such, the photochromic device 10 includes the photochromic layer 20, a pair of transparent conductive layers 30X, 30Y located on both sides of the photochromic layer 20, and a pair of transparent substrate layers 40X, 40Y located on both sides of the pair of transparent conductive layers 30X, 30Y. Each pair of transparent conductive layers 30X, 30Y and transparent substrate layers 40X, 40Y constitutes an "outer support layer" located on both sides of the photochromic layer 20.

[0041] The transparent conductive layers 30X and 30Y are transparent layers having electrical conductivity. Examples of materials that can be used to form the transparent conductive layers 30X and 30Y include indium tin oxide (ITO), fluorine-doped tin oxide (FTO), tin oxide, zinc oxide, carbon nanotubes (CNT), polymers containing poly(3,4-ethylenedioxythiophene) (PEDOT), and multilayer films containing Ag alloy thin films. The transparent substrate layers 40X and 40Y are layers that contain a material such as PET (Polyethylene Terephthalate).

[0042] In addition, an additional or alternative layer may be provided as an "outer support layer" located outside the transparent substrate layers 40X and 40Y. In other words, there is flexibility in the number and type of "outer support layer," allowing for various design modifications. For example, a transparent support layer made of a transparent substrate may be provided as the "outer support layer." Examples of the transparent support layer include a glass substrate, a silicon substrate, or a polymer film made of polyethylene, polystyrene, polyethylene terephthalate, polyvinyl alcohol, polycarbonate, polyvinyl chloride, polyimide, polysulfone, cycloolefin polymer, triacetyl cellulose, etc. Furthermore, examples of the "outer support layer" include a layer for protecting the dimming layer 20, the transparent conductive layer 30X and 30Y, or the transparent substrate layers 40X and 40Y, a layer that contributes to controlling the light transmittance of the dimming device 10, and a layer that enhances the strength, heat resistance, and other properties of the dimming device 10.

[0043] In the example of Fig. 1, the ends (end faces) of the light control devices 10 are flush with each other and are aligned without any misalignment when viewed in a plan view. In contrast, in the example of Fig. 2, the ends (end faces) of the light control devices 10 are not flush with each other and are aligned so that their positions are misaligned when viewed in a plan view.

[0044] 2 , when focusing on the right end portion (right end surface) of the dimming device 10, the transparent conductive layer 30X and the transparent substrate layer 40X provided on one surface (top surface in the figure) of the dimming layer 20 protrude to the right beyond the dimming layer 20. On the other hand, when focusing on the left end portion (left end surface) of the dimming device 10, the transparent conductive layer 30Y and the transparent substrate layer 40Y provided on the other surface (bottom surface in the figure) of the dimming layer 20 protrude to the left beyond the dimming layer 20.

[0045] An electrode section 50X that applies a drive voltage to the light control device 10 (light control layer 20) is provided on the lower surface of the transparent conductive layer 30X that protrudes to the right of the light control layer 20. An electrode section 50Y that applies a drive voltage to the light control device 10 (light control layer 20) is provided on the upper surface of the transparent conductive layer 30Y that protrudes to the left of the light control layer 20. A wiring section 60X is connected to the electrode section 50X, and a wiring section 60Y is connected to the electrode section 50Y, and the wiring section 60X and the wiring section 60Y are connected to a drive power supply 70. The wiring section 60X and the wiring section 60Y may be formed, for example, from an FPC (Flexible Printed Circuit) or the like.

[0046] In the dimming device 10 configured 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.

[0047] When no driving voltage is applied between the transparent conductive layers 30X and 30Y (the light-adjusting layer 20), the orientation of the long axes of the liquid crystal molecules in the light-adjusting layer 20 is irregular. As a result, light incident on the light-adjusting layer 20 is scattered, and the dichroic dye contained in the light-adjusting layer 20 and the black spacers have a synergistic effect, causing the light-adjusting device 10 to appear black. In other words, the light-adjusting device 10 is opaque.

[0048] On the other hand, when a drive voltage is applied between the transparent conductive layers 30X and 30Y (the dimming layer 20), the liquid crystal molecules of the dimming device 10 are oriented, with the long axis direction of the liquid crystal molecules oriented along 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 device 10 becomes transparent. In this way, the dimming device 10 functions as a normal type (normal mode).

[0049] The light control device 10 is used for various purposes, for example, by cutting into a desired shape a large sheet made of a multilayer body including each layer that constitutes the light control device 10. For example, the light control device 10 can be used in various applications, such as a light control film that normally suffices for transparent glass but blocks view from inside and outside only at specific times, office partitions, laminated glass, frosted glass, etc. Furthermore, the light control device 10 can be installed in the upper end region of an automobile windshield to provide a partial sun visor function, or can be used in an automobile sunroof or side window.

[0050] 3A and 3B are diagrams showing the difference in the orientation of liquid crystal molecules when the normal-type, black dimming dimmer 10 is in an opaque state when not energized (powered off) and in a transparent state when energized (powered on).

[0051] 3A, when a normal-type light control device 10 is in an opaque state without power (when the power is off), the liquid crystal molecules located inside the light control layer 20 are unevenly oriented, and the refractive indices of the liquid crystal molecules and the polymer do not match, resulting in a scattering state and opacity. Moreover, the synergistic effect of the dichroic dye and black spacers (black functional particles) contained in the light control layer 20 ensures black dimming in the opaque state of the light control device 10.

[0052] As shown in Figure 3B, when the normal-type light control device 10 is in a transparent state when powered on (when the power is on), the liquid crystal molecules located inside the light control layer 20 are balanced (their long axes are aligned in the left-right direction in the figure), and the refractive indices of the liquid crystal molecules and the polymer match, resulting in transparency. Furthermore, the synergistic effect of the dichroic dye and black spacers (black functional fine particles) contained in the light control layer 20 absorbs and reduces scattered light, thereby reducing whitening caused by scattered light when viewed from an oblique angle, and keeping the haze within a viewing angle of 170° in the transparent state to 14% or less, and more preferably 5% or less. In other words, when the normal-type light control device 10 is in a transparent state when powered on, there are few areas that appear cloudy when viewed from any angle, resulting in high transparency.

[0053] Furthermore, in FIG. 1, the thickness of the light-controlling layer 20 is denoted by the reference symbol 20T, the thickness of the transparent conductive layers 30X and 30Y is denoted by the reference symbol 30T, and the thickness of the transparent substrate layers 40X and 40Y is denoted by the reference symbol 40T.

[0054] The thickness 20T of the switchable layer 20 is preferably 12 μm or more and 25 μm or less, and more preferably 15 μm or more and 22 μm or less. By setting the thickness 20T of the switchable layer 20 to satisfy the above range, combined with the inclusion of a dichroic dye and black spacers in the switchable layer 20 (a synergistic effect), it becomes possible to further reduce (lower) the haze within a viewing angle of 170° in the transparent state (for example, 14% or less, more preferably 5% or less). In other words, when the normal-type switchable device 10 is in a transparent state with power applied, there are fewer areas that appear cloudy when viewed from any angle, and transparency can be increased.

[0055] The film thickness 30T of the transparent conductive layers 30X and 30Y is preferably set to 10 to 30 nm, which can contribute to optimizing the function of the light control device 10.

[0056] The film thickness 40T of the transparent substrate layers 40X and 40Y is preferably set to 120 to 200 μm, which can contribute to optimizing the function of the light control device 10.

[0057] 4 is a scanning electron microscope (SEM) image (normal product, liquid crystal layer cross-sectional structure) showing the cross-sectional structure of the light-controlling layer 20 in the transparent state when the normal-type, black-dimming light control device 10 is energized (powered on). Although it is not as easy to understand as the schematic diagram in FIG. 3, it can be seen that the liquid crystal molecules located inside the light-controlling layer 20 are balanced in orientation.

[0058] FIG. 5 is a diagram showing an example of a cross-sectional structure of a light-modulating layer including a dichroic dye and black spacers.

[0059] 5, the components included in the light-controlling layer 20 are denoted by the following symbols: the transparent polymer layer is denoted by symbol 20P, the gap is denoted by symbol 20D, the liquid crystal composition is denoted by symbol 20LC, the liquid crystal compound is denoted by symbol LCM, the dichroic dye is denoted by symbol DD, and the black spacer is denoted by symbol SP.

[0060] The light-controlling layer 20 includes a transparent polymer layer 20P including a plurality of voids 20D, a liquid crystal composition 20LC located in the voids 20D, and black spacers SP. The liquid crystal composition 20LC includes a liquid crystal compound LCM and a dichroic dye DD. The first brightness of the black spacers SP is L. ＊ 1, and the second brightness of the light control device 10 in the opaque state is L ＊ 2, and the second lightness L ＊ 2 to 1st brightness L ＊ The absolute value of the brightness difference obtained by subtracting 1 is ΔL ＊ In a plan view opposite to the plane in which the light-adjusting device 10 extends, the area occupancy (%) of the black spacers SP in the light-adjusting layer 20 is SR. The light-adjusting sheet 20 preferably satisfies the following condition 1. (Condition 1) Lightness difference ΔL ＊ The multiplication value of ΔL and the area occupancy rate SR satisfies the following: 20≦ΔL ＊ ×SR≦81

[0061] When the amount of black spacers SP included in the light-controlling layer 20 is at least, and the lightness difference, which is the difference between the first lightness of each black spacer SP and the second lightness of the light-controlling device 10, is large, an observer viewing the light-controlling device 10 is likely to see each black spacer SP dispersed throughout the light-controlling device 10. On the other hand, even when the lightness difference is small, if the area ratio occupied by all the black spacers SP in the light-controlling layer 20 is high, the probability that each black spacer SP will be visible to the observer is high, and the possibility that a collection of multiple black spacers SP will be seen by the observer as a single object also increases. This causes the observer to recognize that there is unevenness in the appearance of the light-controlling device 10 within the plane of the light-controlling device 10.

[0062] In this regard, when the product of the brightness difference between the black spacers SP and the light-adjusting device 10 and the area occupancy rate of the black spacers SP satisfies the above range, the brightness difference and the area occupancy rate are prevented from becoming excessively large in the light-adjusting device 10. This makes it difficult for the black spacers SP in the light-adjusting layer 20 to be visually recognized, thereby reducing unevenness in the appearance of the light-adjusting device 10 within its plane.

[0063] When it is required to further suppress the unevenness of the appearance within the surface of the light control device 10, the brightness difference ΔL ＊ It is preferable that the upper limit of the multiplication value of the surface area ratio SR be small. The upper limit may be, for example, 70, 60, or 30.

[0064] The light control device 10 may satisfy the following conditions 2 and 3. This can enhance the effectiveness of satisfying the above-mentioned condition 1. (Condition 2) Lightness difference ΔL ＊ is equal to or greater than 20 and equal to or less than 74. (Condition 3) The area occupancy rate SR is equal to or greater than 1% and equal to or less than 3%.

[0065] In the light-adjusting device 10, the average diameter (particle size, average particle size) of the black spacers SP may be 12 μm or more and 25 μm or less, which is the preferred film thickness of the light-adjusting layer 20. As a result, the lightness difference ΔL ＊ This can enhance the effectiveness of satisfying Condition 1 relating to the multiplication value of and the area occupancy SR.

[0066] The liquid crystal composition 20LC contains a liquid crystal compound LCM. The mass content of the liquid crystal compound LCM relative to the mass of the light-controlling layer 20 may be, for example, 40% by mass or more and 65% by mass or less. That is, the mass M20 of the light-controlling layer 20 and the mass MLCM of the liquid crystal compound LCM may satisfy the following formula: The mass M20 of the light-controlling layer 20 is the sum of the mass MLCM of the liquid crystal compound LCM, the mass M20P of the transparent polymer layer 20P, and the mass MSP of the black spacers SP. 40 (mass%)≦(MLCM / M20)×100≦65 (mass%)

[0067] The liquid crystal composition 20LC may contain additives such as an antifoaming agent, an antioxidant, a weathering agent, a solvent, a viscosity reducing agent, etc. The weathering agent may be an ultraviolet absorber or a light stabilizer.

[0068] The liquid crystal compound LCM may have a positive dielectric anisotropy. When the liquid crystal compound LCM has a positive dielectric anisotropy, the dielectric constant ε∥ of the liquid crystal compound LCM in the long axis direction is higher than the dielectric constant ε⊥ of the liquid crystal compound LCM in the short axis direction.

[0069] The transparent polymer layer 20P is a cured product of a photopolymerizable compound. The light for polymerizing 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 lower and upper limits of the content of the transparent polymer layer 20P in the light-controlling layer 20 are within a range in which liquid crystal particles composed of the liquid crystal compound LCM phase-separate from the polymer of the photopolymerizable compound during the polymerization process of the photopolymerizable compound. If it is necessary to increase the mechanical strength of the transparent polymer layer 20P, it is preferable that the lower limit of the content of the transparent polymer layer 20P is high. If it is necessary to lower the voltage for driving the liquid crystal compound LCM, it is preferable that the upper limit of the content of the transparent polymer layer 20P is low.

[0070] By changing the size of the voids 20D in the transparent polymer layer 20P from the first value to the second value, the second brightness L of the light control device 10 is ＊ The smaller the size of the voids 20D in the transparent polymer layer 20P, the more easily light scattering occurs in the light-adjusting layer 20. Therefore, the second brightness L ＊ On the other hand, the larger the size of the voids 20D in the transparent polymer layer 20P, the less likely light scattering occurs in the light-adjusting layer 20. ＊ 2 tends to decrease.

[0071] The black spacers SP are dispersed throughout the transparent polymer layer 20P. The thickness of the black spacers SP may determine the thickness of the light-switching layer 20. The thickness of the black spacers SP may be the particle size of the black spacers SP. The black spacers SP may make the thickness of the light-switching layer 20 uniform. The black spacers SP may be bead spacers or photospacers formed by exposing and developing a photoresist. The color of the black spacers SP is preferably the same black as the color of the dichroic dye DD.

[0072] For example, the outer surface of the black spacer SP may be black. In this case, light transmission through the outer surface of the black spacer SP is suppressed, and therefore, the transmitted light is prevented from being locally visible within the plane of the light control device 10. This further reduces unevenness in the appearance within the plane of the light control device 10. The black spacer SP may have an outer surface and a center portion covered by the outer surface, and the center portion may be black. In this case, since the center portion of the black spacer SP is black in addition to the outer surface of the black spacer SP, the absorbance of the black spacer SP is further increased. This further reduces light transmission through the black spacer SP, and therefore, the black spacer SP becomes less visible. As a result, unevenness in the appearance within the plane of the light control device 10 is further reduced.

[0073] For example, by changing the color of the black spacers SP from the first color to the second color, the first brightness L of the black spacers SP can be reduced. ＊ For example, the first brightness L of the black spacer SP can be changed by changing the area occupancy rate of the region exhibiting a predetermined color on the outer surface of the black spacer SP from the first value to the second value. ＊ It is possible to change 1 from a first value to a second value.

[0074] For example, by changing the number of black spacers SP per unit area from a first value to a second value, it is possible to change the area occupancy rate SR of the black spacers SP from a first value to a second value. Also, by changing the average diameter of the black spacers SP from a first value to a second value, it is possible to change the area occupancy rate SR of the black spacers SP from a first value to a second value.

[0075] The black spacers SP may have a spherical or columnar shape. The size of the black spacers SP in the thickness direction of the photochromic layer 20 is appropriately changed based on the thickness required for the photochromic layer 20. In this embodiment, the size of the black spacers SP in the thickness direction of the photochromic layer 20 may be set, for example, in accordance with the preferred film thickness of the photochromic layer 20, which is 12 μm or more and 25 μm or less. When the black spacers SP have a spherical shape, the average particle diameter of the black spacers SP may be, for example, 12 μm or more and 25 μm or less. The average particle diameter of the black spacers SP is obtained using a particle size distribution measuring device using principles such as laser light scattering, electrical resistance change, and image analysis after imaging. The average particle diameter of the black spacers SP is the number average particle diameter. When the black spacers SP have a columnar shape, the average diameter may be, for example, 12 μm or more and 25 μm or less. When the average particle diameter of the black spacers SP is within the range of 12 μm or more and 25 μm or less, the lightness difference ΔL ＊ Therefore, it is more effective that the multiplied value of the area occupancy SR satisfies the above range.

[0076] As described above, the area occupancy SR of the black spacers SP may be, for example, 1% to 3%. The area occupancy SR is the ratio of the area occupied by the black spacers SP to the unit area of ​​the light control device 10. The area occupied by the black spacers SP is obtained by observing the transparent light control device 10 from a viewpoint facing one of a pair of opposing surfaces in the thickness direction. An example of the unit area of ​​the light control device 10 is 1 mm x 1 mm. The area occupied by the black spacers SP is calculated by observing the unit area of ​​the transparent light control device 10 using an optical microscope. The slight refractive index difference between the black spacers SP and the transparent polymer layer 20P makes the area corresponding to the black spacers SP slightly darker than the surrounding area in the image captured by the optical microscope. The area occupied by the black spacers SP is obtained by binarizing the image captured by the optical microscope and then summing the areas of the granular areas that are slightly darker than the surrounding area. When the black spacers SP have a spherical shape, the granular regions have a spherical shape, and when the black spacers SP have a columnar shape, the granular regions have a rectangular shape.

[0077] The dichroic dye DD exhibits color (black) when driven by a guest-host mode using the liquid crystal compound LCM as a host. The dichroic dye DD is, for example, at least one selected from the group consisting of 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. When increased light resistance and an increased dichroic ratio are required, the dichroic dye DD is preferably at least one selected from the group consisting of azo compounds and anthraquinone compounds, and more preferably an azo compound.

[0078] The dichroic dye DD preferably exhibits black, which is the same color as the black spacers SP. The dichroic dye DD may exhibit black by one type of compound or a combination of two or more types of compounds.

[0079] For example, by changing the content of the dichroic dye DD in the light-adjusting layer 20 from a first value to a second value, the second lightness L ＊ 2 can be changed from a first value to a second value.

[0080] <Numerical Example & Demonstration Experiment / Normal Type, Black Dimming> The inventor conducted an experiment to demonstrate the superiority of the light control device (light control sheet, light control film) 10 of this embodiment. The results are shown in FIG. 6.

[0081] As shown in FIG. 6 , samples according to Examples 1-5 of the present invention and samples according to Comparative Examples 1-4 were prepared. These samples all had the same normal driving mode. However, the samples according to Examples 1-5 had a dichroic dye added to the photochromic layer and contained black spacers (black functional fine particles), whereas the samples according to Comparative Examples 1-4 had no dichroic dye added to the photochromic layer and contained white spacers (white functional fine particles). Furthermore, the thickness of the photochromic layer was varied in each sample. The total light transmittance (%) of each sample was measured in both the transparent and opaque states (both at a measurement angle of 0° and a viewing angle of 0°). Furthermore, the haze (%) of each sample was measured in the transparent state. The haze was measured at three different angles: a measurement angle of 0° and a viewing angle of 0°, a measurement angle of 75° and a viewing angle of 150°, and a measurement angle of 85° and a viewing angle of 170°.

[0082] The haze measurement method is as follows. An open-chamber haze meter (BYK haze meter, haze-garadi) was used. A jig was installed that could hold the light-adjusting device (light control device) to be measured at a variable angle relative to the parallel line between the light source and the light-receiving sensor. The angle between the light source and the light-receiving sensor and the light-adjusting device was defined, and the haze value measured for the light-adjusting device held in that state was defined as the haze value at that angle. In this case, the viewing angle value = |measurement angle| × 2 holds. Furthermore, the total light transmittance measurement method was performed using an NDH7000SP manufactured by Nippon Denshoku.

[0083] 6, areas that satisfy the constituent requirements of the light control device of this embodiment, i.e., that a dichroic dye is added to the light control layer, that the light control layer contains black spacers, that the film thickness of the light control layer is 12 μm or more and 25 μm or less (or, more preferably, 15 μm or more and 22 μm or less), that the total light transmittance in the transparent state is 40% or more, that the total light transmittance in the opaque state is 20% or less, and that the haze is 14% or less (particularly, that the haze within a viewing angle of 170° in the transparent state is 14% or less), are depicted in a clear state without gray fill.On the other hand, areas that do not satisfy the constituent requirements of the light control device of this embodiment are depicted in gray fill.

[0084] 6, the samples of Examples 1-5 satisfy all of the following requirements: a dichroic dye is added to the photochromic layer, the photochromic layer contains black spacers, the photochromic layer has a thickness of 12 μm or more and 25 μm or less, the total light transmittance in the transparent state is 40% or more, the total light transmittance in the opaque state is 20% or less, and the haze is 14% or less (particularly, the haze within a viewing angle of 170° in the transparent state is 14% or less). Therefore, in the transparent state when the power is applied to a normal type photochromic device, there are few areas that appear cloudy when viewed from any angle, and transparency can be increased.

[0085] On the other hand, the samples of Comparative Examples 1-4 do not satisfy the constituent requirements of adding a dichroic dye to the photochromic layer and including black spacers. Furthermore, the sample of Comparative Example 1 has a photochromic layer thickness of 30 μm, which exceeds the upper limit of this embodiment, making areas that appear cloudy when the normal-type photochromic device is in a transparent state when powered on more prominent. Furthermore, the sample of Comparative Example 4 has a photochromic layer thickness of 14 μm, which is below the lower limit of the more preferred range of 15 μm to 22 μm, which may result in insufficient light-blocking effect when the normal-type photochromic device is in an opaque state when powered off. Furthermore, the samples of Comparative Examples 1-4 do not satisfy the constituent requirement of a total light transmittance of 20% or less in the opaque state, making it impossible to achieve both the function of the photochromic device in the transparent state (high visibility) and the function of the photochromic device in the opaque state (high light-blocking ability). Furthermore, the sample according to Comparative Example 1-4 does not satisfy the constituent requirement that the haze be 14% or less (particularly, that the haze be 14% or less within a viewing angle of 170° in the transparent state), and therefore the areas that appear cloudy in the transparent state when the normal type dimming device is energized become more noticeable.

[0086] As described above, the dimming device (normal type, black dimming) of this embodiment has a dimming layer and outer support layers located on both sides of the dimming layer, the dimming layer becoming transparent when current is applied to the dimming layer through the outer support layer, and becoming opaque when current is not applied to the dimming layer through the outer support layer, the dimming layer containing a dichroic dye and a black spacer, having a black color in the opaque state, a haze of 14% or less within a viewing angle of 170° in the transparent state, and a film thickness of the dimming layer of 12 μm or more and 25 μm or less. This makes it possible to provide a dimming device and dimming module that, when in a transparent state when current is applied, has few areas that appear cloudy and has high transparency when viewed from any angle.

[0087] <Technical concept of the present invention / Reverse type / black dimming> The inventors have completed the present invention through research and development of a dimming device and dimming module that can increase transparency when viewed from any angle, with few areas that appear cloudy, when the reverse type dimming device is in a transparent state when not powered.

[0088] The present inventors investigated the reason why a transparent light control device (light control sheet, light control film) appears cloudy (whitening, high haze value) when viewed obliquely, and discovered the following: In light control devices (light control sheets, light control films) that use polymer-dispersed liquid crystals, due to their structure, when transparent, even if the liquid crystals are aligned, the transmitted light is not parallel to incident light from an oblique angle and is scattered, resulting in reduced transparency.

[0089] In order to solve (eliminate) the above technical problems (causes), the light control device (light control sheet, light control film) of this embodiment has the following configuration requirements. The light control device (light control sheet, light control film) of this embodiment has a light control layer and outer support layers located on both sides of the light control layer. The light control device (light control sheet, light control film) of this embodiment is a reverse type (reverse mode) in which the light control layer is transparent when no current is applied to the light control layer through the outer support layer, and is opaque when current is applied to the light control layer through the outer support layer. The light control layer contains a dichroic dye (at least one type of dichroic dye) and black spacers (black functional fine particles), and is black in color in the opaque state (so-called black light control). Furthermore, the film thickness of the light control layer is 15 μm or less, more preferably 5 μm or more and 10 μm or less. In this way, by including a dichroic dye (at least one type of dichroic dye) and black spacers (black functional particles) in the light-controlling layer and setting the film thickness of the light-controlling layer to 15 μm or less, more preferably 5 μm or more and 10 μm or less, scattered light is absorbed and reduced, thereby reducing whitening due to scattered light when viewed from an oblique angle, and the haze within a viewing angle of 170° in the transparent state can be kept to 14% or less, more preferably 7% or less. In other words, in the transparent state when not energized, a reverse-type light-controlling device (light-controlling sheet, light-control film) can be effectively prevented from appearing cloudy and has high transparency when viewed from any angle. This makes it possible to realize a light-controlling device (light-controlling sheet, light-control film) with a wide viewing angle that is suitable for, for example, vehicle interiors and living spaces.

[0090] By setting the film thickness of the photochromic layer containing a dichroic dye (at least one type of dichroic dye) and black spacers (black functional fine particles) to 15 μm or less, more preferably 5 μm or more and 10 μm or less (due to the synergistic effect of these), scattered light is absorbed by the dichroic dye and black spacers inside the photochromic layer, thereby realizing not only high light-blocking properties in the opaque state but also high visibility in the transparent state (for example, a haze of 14% or less within a viewing angle of 170° in the transparent state).

[0091] The inventors conducted extensive research into the optimal film thickness for a reverse-type, black-colored light-controlling device (light-controlling sheet, light-controlling film) to minimize areas that appear cloudy and increase transparency when viewed from any angle in a transparent state when no current is applied. As a result, they discovered that the film thickness in the above range is preferable. If the film thickness of the light-controlling layer is too large (e.g., greater than 15 μm), the number of areas that appear cloudy when the reverse-type, black-colored light-controlling device (light-controlling sheet, light-control film) is in a transparent state when no current is applied may increase. If the film thickness of the light-controlling layer is too small (e.g., less than 5 μm), the function (high light-blocking ability) of the light-controlling device (light-controlling sheet, light-control film) in the opaque state becomes insufficient. Thus, if the film thickness of the light-controlling layer is inappropriate, it becomes impossible to achieve both the function (high visibility) of the light-controlling device in the transparent state and the function (high light-blocking ability) of the light-controlling device in the opaque state.

[0092] The light-controlling layer can be a polymer-dispersed liquid crystal layer, and the outer support layer can have a pair of alignment layers located on either side of the light-controlling layer, a pair of transparent conductive layers located on either side of the pair of alignment layers, and a pair of transparent substrate layers located on either side of the pair of transparent conductive layers.

[0093] 7 and 8 are first and second diagrams showing an example of the configuration of a reverse-type black dimming light control device (dimming sheet, dimming film) 10″. FIG. 7 mainly illustrates the layered structure of the dimming device 10″, while FIG. 8 mainly illustrates the structure including the drive mechanism (electrodes and wiring) of the dimming device 10″. As shown in FIG. 7 , the dimming device 10″ is used by being attached (pasted) to a light-transmitting member (light-transmitting plate, light-transmitting window) designated by the reference symbol 10X″. In this case, the dimming device 10″ may have an adhesive layer for attaching it to the light-transmitting member 10X″. The dimming module of this embodiment is configured by attaching the dimming device 10″ to the light-transmitting member 10X″.

[0094] The light control device 10" has a light control layer (liquid crystal layer) 20". The light control layer 20" has the same structure as the light control layer 20 described above, so a duplicated description will be omitted.

[0095] An alignment layer 30X" is provided on the outside of one surface (top surface in the figure) of the light-controlling layer 20", and an alignment layer 30Y" is provided on the outside of the other surface (bottom surface in the figure) of the light-controlling layer 20". The alignment layers 30X″ and 30Y″ are layers that control the alignment of liquid crystal molecules contained in the light-controlling layer 20″. When no driving voltage is applied, the liquid crystal molecules are aligned along the normal direction of the alignment layers 30X″ and 30Y″. On the other hand, when a driving voltage is applied, the orientation of the long axis direction of the liquid crystal molecules becomes irregular. In a configuration including the alignment layers 30X″ and 30Y″, the light-controlling device 10″ becomes opaque when a driving voltage is applied to the light-controlling layer 20″, and becomes transparent when a driving voltage is not applied to the light-controlling layer 20″ (functioning as a reverse type (reverse mode)). Examples of materials that can be used to form the alignment layers 30X″ and 30Y″ 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 alignment treatments for forming the alignment layers 30X″ and 30Y″ include rubbing, polarized light irradiation, and microfabrication.

[0096] A transparent conductive layer 40X" is provided on the outside of one surface (top surface in the figure) of the alignment layer 30X", and a transparent substrate layer 50X" is provided on the outside of the transparent conductive layer 40X". A transparent conductive layer 40Y" is provided on the outside of the other surface (bottom surface in the figure) of the alignment layer 30Y", and a transparent substrate layer 50Y" is provided on the outside of the transparent conductive layer 40Y". Thus, the dimming device 10" has a dimming layer 20", a pair of alignment layers 30X", 30Y" located on both sides of the dimming layer 20", a pair of transparent conductive layers 40X", 40Y" located on both sides of the pair of alignment layers 30X", 30Y", and a pair of transparent substrate layers 50X", 50Y" located on both sides of the pair of transparent conductive layers 40X", 40Y". Each pair of alignment layers 30X", 30Y", transparent conductive layers 40X", 40Y", and transparent substrate layers 50X", 50Y" constitutes an "outer support layer" located on both sides of the dimming layer 20".

[0097] The transparent conductive layers 40X″, 40Y″ have the same structure as the transparent conductive layers 30X, 30Y described above, and therefore a duplicated description will be omitted. The transparent base material layers 50X″, 50Y″ have the same structure as the transparent base material layers 40X, 40Y described above, and therefore a duplicated description will be omitted.

[0098] Note that an additional / alternative layer may be provided as an "outer support layer" located outside the transparent substrate layers 50X" and 50Y". In other words, there is a degree of freedom in the number and type of "outer support layers", and various design modifications are possible. For example, a transparent support layer made of a transparent substrate may be provided as the "outer support layer". As the transparent support layer, for example, a glass substrate, a silicon substrate, or a polymer film made of polyethylene, polystyrene, polyethylene terephthalate, polyvinyl alcohol, polycarbonate, polyvinyl chloride, polyimide, polysulfone, cycloolefin polymer, triacetyl cellulose, or the like may be used. Furthermore, as the "outer support layer", for example, a layer for protecting the light control layer 20", the alignment layer 30X", 30Y", the transparent conductive layer 40X", 40Y", or the transparent substrate layers 50X", 50Y", a layer that contributes to controlling the light transmittance of the light control device 10", a layer that improves the strength, heat resistance, or other properties of the light control device 10", or the like may be used.

[0099] In the example of FIG. 7 , the ends (end faces) of the dimmer 10″ are flush with each other and are aligned without any misalignment when viewed in a plan view. In contrast to this, in the example of FIG. 8 , the ends (end faces) of the dimmer 10″ are not flush with each other and are aligned so that their positions are misaligned when viewed in a plan view.

[0100] In the example of Figure 8, when focusing on the right end (right end surface) of the dimming device 10", the transparent conductive layer 40X" and the transparent substrate layer 50X" provided on one surface (top surface in the figure) of the dimming layer 20" and the alignment layer 30X" protrude to the right beyond the dimming layer 20" and the alignment layer 30X". On the other hand, when focusing on the left end (left end surface) of the dimming device 10", the transparent conductive layer 40Y" and the transparent substrate layer 50Y" provided on the other surface (bottom surface in the figure) of the dimming layer 20" and the alignment layer 30Y" protrude to the left beyond the dimming layer 20" and the alignment layer 30Y".

[0101] An electrode section 60X" for applying a drive voltage to the light control device 10" (light control layer 20") is provided on the lower surface of the transparent conductive layer 40X" that protrudes to the right beyond the light control layer 20" and the alignment layer 30X". An electrode section 60Y" for applying a drive voltage to the light control device 10" (light control layer 20") is provided on the upper surface of the transparent conductive layer 40Y" that protrudes to the left beyond the light control layer 20" and the alignment layer 30Y". A wiring section 70X" is connected to the electrode section 60X", and a wiring section 70Y" is connected to the electrode section 60Y", and the wiring section 70X" and the wiring section 70Y" are connected to a drive power source 80". The wiring section 70X" and the wiring section 70Y" may be formed, for example, from an FPC (Flexible Printed Circuit) or the like.

[0102] In the dimming device 10" configured as described above, when a driving current is passed through the transparent conductive layers 40X" and 40Y" via the electrode sections 60X" and 60Y", the wiring sections 70X" and 70Y", and the driving power supply 80", a driving voltage is applied between the transparent conductive layers 40X" and 40Y", i.e., between the dimming layer 20" and the alignment layers 30X" and 30Y".

[0103] When a driving voltage is applied between the transparent conductive layers 40X" and 40Y" (the light-controlling layer 20" and the alignment layers 30X" and 30Y"), the orientation of the long axes of the liquid crystal molecules in the light-controlling layer 20" is irregular. Therefore, light incident on the light-controlling layer 20" is scattered, and the dichroic dye contained in the light-controlling layer 20" and the black spacers have a synergistic effect, causing the light-controlling device 10" to appear black. In other words, the light-controlling device 10" is opaque.

[0104] On the other hand, when no driving voltage is applied between the transparent conductive layers 40X" and 40Y" (the dimming layer 20" and the alignment layers 30X" and 30Y"), the liquid crystal molecules of the dimming device 10" are aligned, and the long axis direction of the liquid crystal molecules is aligned along the electric field direction between the transparent conductive layers 40X" and 40Y". As a result, light is more easily transmitted through the dimming layer 20", and the dimming device 10" becomes transparent. In this way, the dimming device 10" functions as a reverse type (reverse mode).

[0105] The light control device 10" is used for various purposes, for example, by being cut into a desired shape from a large sheet made of a multilayer body including each layer that constitutes the light control device 10". For example, the light control device 10" can be applied to various purposes such as a light control film that normally suffices for transparent glass but that blocks view from inside or outside only at specific times, an office partition, laminated glass, or frosted glass. Furthermore, the light control device 10" can be installed in the upper end region of an automobile windshield to provide a partial sun visor function, or can be applied to an in-vehicle sunroof or side window.

[0106] 9A and 9B are diagrams showing the difference in the orientation of liquid crystal molecules when a reverse-type light control device 10" is in a transparent state when not energized (when the power is off) and in an opaque state when energized (when the power is on). FIGS. 9A and 9B schematically show the cross-sectional structure of a light control layer 20". As shown in FIGS. 9A and 9B, liquid crystal molecules of a liquid crystal composition are positioned so as to fill voids inside the light control layer 20". The liquid crystal molecules of the liquid crystal composition are positioned near (along) the upper and lower alignment layers 30X" and 30Y" inside the light control layer 20". Inside the light control layer 20", towards the center away from the upper and lower alignment layers 30X" and 30Y", no liquid crystal molecules of the liquid crystal composition are positioned, and a resin layer is formed.

[0107] As shown in FIG. 9A , when the reverse-type light control device 10″ is in a transparent state when not energized (when the power is off), the liquid crystal molecules located inside the light control layer 20″ are balanced (their long axes are aligned in the vertical direction in the figure), and the refractive indexes of the liquid crystal molecules and the polymer match, resulting in transparency. Furthermore, the dichroic dye and black spacers (black functional fine particles) contained in the light control layer 20″ have a synergistic effect of absorbing and reducing scattered light, thereby reducing whitening due to scattered light when viewed from an oblique angle, and making it possible to keep the haze within a viewing angle of 170° in the transparent state to 14% or less, more preferably 7% or less. In other words, when the reverse-type light control device 10″ is in a transparent state when not energized, there are few areas that appear cloudy when viewed from any angle, and transparency can be increased.

[0108] As shown in FIG. 9B , when the reverse-type light control device 10″ is in an opaque state when powered on (when the power is on), the liquid crystal molecules located inside the light control layer 20″ are unbalancedly oriented, and the refractive indices of the liquid crystal molecules and the polymer do not match, resulting in a scattering state and opacity. Moreover, the synergistic effect of the dichroic dye and black spacers (black functional particles) contained in the light control layer 20″ ensures black dimming in the opaque state of the light control device 10″.

[0109] Furthermore, in Figure 7, the film thickness of the dimming layer 20" is denoted by the symbol 20T", the film thickness of the alignment layers 30X" and 30Y" is denoted by the symbol 30T", the film thickness of the transparent conductive layers 40X" and 40Y" is denoted by the symbol 40T", and the film thickness of the transparent substrate layers 50X" and 50Y" is denoted by the symbol 50T".

[0110] The film thickness 20T" of the switchable layer 20" is preferably 15 μm or less, and more preferably 5 μm or more and 10 μm or less. By setting the film thickness 20T" of the switchable layer 20" so as to satisfy the above range, combined with the inclusion of a dichroic dye and black spacers in the switchable layer 20" (synergistic effect), it becomes possible to set the haze within a viewing angle of 170° in the transparent state to be small (low) (for example, 14% or less, more preferably 7% or less). In other words, when the reverse-type switchable device 10" is in a transparent state when not energized, there are few areas that appear cloudy when viewed from any angle, and transparency can be increased.

[0111] The film thickness 30T'' of the alignment layers 30X'' and 30Y'' is preferably set to 50 to 300 nm, which can contribute to optimizing the function of the light control device 10''.

[0112] The film thickness 40T'' of the transparent conductive layers 40X'' and 40Y'' is preferably set to 10 to 30 nm, which can contribute to optimizing the function of the light control device 10''.

[0113] The film thickness 50T'' of the transparent substrate layers 50X'' and 50Y'' is preferably set to 120 to 200 μm, which can contribute to optimizing the function of the light control device 10''.

[0114] FIG. 10 is a SEM (Scanning Electron Microscope) image showing the cross-sectional structure of the light-controlling layer 20″ in a transparent state when the reverse-type light control device 10″ is not energized (when the power is off) (reverse product, liquid crystal layer cross-sectional structure). Although it is not as easy to understand as the schematic diagram in FIG. 9, it can be seen that the liquid crystal molecules located inside the light-controlling layer 20″ are oriented in a balanced manner.

[0115] Here, the cross-sectional structure of the light-adjusting layer containing the dichroic dye and the black spacers is the same as that shown in FIG. 5 described above. In the light-adjusting device 10", the average diameter (particle size, average particle size) of the black spacers SP may be 15 μm or less (more preferably 5 μm or more and 10 μm or less), which is the preferred film thickness of the light-adjusting layer 20". As a result, the lightness difference ΔL ＊ This can enhance the effectiveness of satisfying Condition 1 relating to the multiplication of the surface area ratio SR and the surface area ratio SR. The size of the black spacers SP in the thickness direction of the photochromic layer 20" is appropriately changed based on the thickness required for the photochromic layer 20". In this embodiment, the size of the black spacers SP in the thickness direction of the photochromic layer 20" may be set, for example, in accordance with the preferred film thickness of the photochromic layer 20", which is 15 μm or less (more preferably, 5 μm or more and 10 μm or less). When the black spacers SP have a spherical shape, the average particle diameter of the black spacers SP may be, for example, 15 μm or less (more preferably, 5 μm or more and 10 μm or less). The average particle diameter of the black spacers SP is obtained using a particle size distribution measurement device using principles such as laser light scattering, electrical resistance change, and image analysis after imaging. The average particle diameter of the black spacers SP is the number average particle diameter. When the black spacers SP have a columnar shape, the average diameter may be, for example, 15 μm or less (more preferably, 5 μm or more and 10 μm or less). When the average particle diameter of the black spacers SP is within the range of 15 μm or less (more preferably, 5 μm or more and 10 μm or less), the brightness difference ΔL ＊ Therefore, it is more effective that the multiplied value of the area occupancy SR satisfies the above range.

[0116] <Numerical Examples and Demonstration Experiments> The inventors conducted experiments to demonstrate the superiority of the light control device (light control sheet, light control film) 10 ″ of this embodiment. The results are shown in FIG. 11 .

[0117] As shown in FIG. 11 , samples according to Examples 1-3 and Comparative Examples 1-4 of the present invention were prepared. The driving modes of the samples according to Examples 1-3 were all reverse, while the driving modes of the samples according to Comparative Examples 1-4 were all normal. The samples according to Examples 1-3 differed in that a dichroic dye was added to the photochromic layer and the photochromic layer contained black spacers (black functional fine particles), whereas the samples according to Comparative Examples 1-4 differed in that no dichroic dye was added to the photochromic layer and the photochromic layer contained white spacers (white functional fine particles). The thicknesses of the photochromic layers were also varied for each sample. The total light transmittance (%) of each sample was measured in both the transparent and opaque states (both at a measurement angle of 0° and a viewing angle of 0°). The haze (%) of each sample was also measured in the transparent state. The haze was measured at three angles: a measurement angle of 0° and a viewing angle of 0°, a measurement angle of 75° and a viewing angle of 150°, and a measurement angle of 85° and a viewing angle of 170°.

[0118] The haze measurement method is as follows. An open-chamber haze meter (BYK haze meter, haze-garadi) was used. A jig was installed that could hold the light-adjusting device (light control device) to be measured at a variable angle relative to the parallel line between the light source and the light-receiving sensor. The angle between the light source and the light-receiving sensor and the light-adjusting device was defined, and the haze value measured for the light-adjusting device held in that state was defined as the haze value at that angle. In this case, the viewing angle value = |measurement angle| × 2 holds. Furthermore, the total light transmittance measurement method was performed using an NDH7000SP manufactured by Nippon Denshoku.

[0119] 11, areas that satisfy the constituent requirements of the light control device of this embodiment, i.e., that a dichroic dye is added to the light control layer, that the light control layer contains black spacers, that the film thickness of the light control layer is 15 μm or less (or, more preferably, in the range of 5 μm to 10 μm), and that the haze is 14% or less (particularly, that the haze within a viewing angle of 170° in the transparent state is 14% or less), are depicted in a clear state without gray fill. On the other hand, areas that do not satisfy the constituent requirements of the light control device of this embodiment are depicted in gray fill.

[0120] 11, the sample according to Example 1-3 satisfies all of the following requirements: a dichroic dye is added to the photochromic layer, the photochromic layer contains black spacers, the photochromic layer has a thickness of 15 μm or less (or, more preferably, a range of 5 μm or more and 10 μm or less), and the haze is 14% or less (particularly, the haze within a viewing angle of 170° in the transparent state is 14% or less). Therefore, in the transparent state when the reverse-type photochromic device is not energized, there are few areas that appear cloudy when viewed from any angle, and transparency can be increased.

[0121] On the other hand, the sample according to Comparative Example 1-4 does not satisfy the constituent requirements of adding a dichroic dye to the photochromic layer and including black spacers. Furthermore, the sample according to Comparative Example 1-3 has a photochromic layer thickness exceeding the upper limit of the present embodiment (greater than 15 μm), which makes the opaque areas of the reverse-type photochromic device more noticeable when the device is in a transparent state without being energized. Furthermore, the sample according to Comparative Example 4 does not satisfy the preferred range of 5 μm to 10 μm of the present embodiment, which may result in an insufficient light-blocking effect when the device is in a transparent state without being energized. Furthermore, the sample according to Comparative Example 1-4 does not satisfy the constituent requirements of a haze of 14% or less (particularly, a haze of 14% or less within a viewing angle of 170° in the transparent state), which makes the opaque areas of the reverse-type photochromic device more noticeable when the device is in a transparent state without being energized.

[0122] As described above, the dimming device (reverse type, black dimming) of this embodiment has a dimming layer and outer support layers located on both sides of the dimming layer, the dimming layer being transparent when no current is applied to the dimming layer via the outer support layer, and being opaque when current is applied to the dimming layer via the outer support layer, the dimming layer containing a dichroic dye and a black spacer, being black in color in the opaque state, having a haze of 14% or less within a viewing angle of 170° in the transparent state, and having a film thickness of 15 μm or less. This makes it possible to provide a dimming device and dimming module that, in the transparent state when no current is applied, has few areas that appear cloudy and has high transparency when viewed from any angle.

[0123] The present invention is not limited to the above-described embodiments, and various modifications can be made in the implementation stage without departing from the spirit of the invention. Furthermore, the embodiments may be implemented in appropriate combinations, in which case the combined effects can be obtained. Furthermore, the above-described embodiments include various inventions, and various inventions can be extracted by combining selected elements from the disclosed elements. For example, if the problem can be solved and the desired effect can be obtained even if some elements are deleted from all elements shown in the embodiments, the configuration from which these elements are deleted can be extracted as an invention.

[0124] This application is based on Japanese Patent Application No. 2024-083937 filed on May 23, 2024 and Japanese Patent Application No. 2024-083938 filed on May 23, 2024, the contents of which are incorporated herein in their entirety.

Claims

1. A light control device comprising: a photochromic layer; and outer support layers located on both sides of the photochromic layer; the photochromic layer is transparent when current is passed through the outer support layer; and opaque when current is not passed through the outer support layer; the photochromic layer contains a dichroic dye and a black spacer, and is black in color in the opaque state; the haze within a viewing angle of 170° in the transparent state is 14% or less; and the film thickness of the photochromic layer is 12 μm or more and 25 μm or less.

2. The light control device according to claim 1, wherein the haze within a viewing angle of 170° in the transparent state is 5% or less.

3. The light control device according to claim 1 or 2, characterized in that the total light transmittance in the transparent state is 40% or more, and the total light transmittance in the opaque state is 20% or less.

4. A dimming device as described in claim 1 or claim 2, characterized in that the outer support layer has a pair of transparent conductive layers located on both sides of the dimming layer, and a pair of transparent substrate layers located on both sides of the pair of transparent conductive layers.

5. A light-controlling device comprising a light-controlling layer and outer support layers located on both sides of the light-controlling layer, wherein the light-controlling layer is transparent when no current is passed through the outer support layer and is opaque when current is passed through the outer support layer, the light-controlling layer comprising a dichroic dye and a black spacer and having a black color in the opaque state, the haze within a viewing angle of 170° in the transparent state being 14% or less, and the film thickness of the light-controlling layer being 15 μm or less.

6. The light control device according to claim 5, wherein the haze within a viewing angle of 170° in the transparent state is 7% or less.

7. The light control device according to claim 5 or 6, wherein the thickness of the light control layer is 5 μm or more and 10 μm or less.

8. A dimming device as described in claim 5 or claim 6, characterized in that the outer support layer has a pair of alignment layers located on both sides of the dimming layer, a pair of transparent conductive layers located on both sides of the pair of alignment layers, and a pair of transparent substrate layers located on both sides of the pair of transparent conductive layers.

9. The light control device according to claim 1 or claim 5, wherein the light control layer is a polymer dispersed liquid crystal layer.

10. A dimming module having a light-transmitting member and a dimming device attached to the light-transmitting member, wherein the dimming device has a dimming layer and outer support layers located on both sides of the dimming layer, wherein the dimming layer becomes transparent when current is passed through the outer support layer and becomes opaque when current is not passed through the outer support layer, the dimming layer contains a dichroic dye and a black spacer, and is black in color in the opaque state, and has a haze of 14% or less within a viewing angle of 170° in the transparent state, and the film thickness of the dimming layer is 12 μm or more and 25 μm or less.

11. A dimming module having a light-transmitting member and a dimming device attached to the light-transmitting member, wherein the dimming device has a dimming layer and outer support layers located on both sides of the dimming layer, the dimming layer is transparent when no current is passed through the outer support layer, and is opaque when current is passed through the outer support layer, the dimming layer contains a dichroic dye and a black spacer, and is black in color in the opaque state, the haze within a viewing angle of 170° in the transparent state is 14% or less, and the film thickness of the dimming layer is 15 μm or less.

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