Light control device and light control module

Abstract

To provide a light control device and light control module, which increase transparency with less areas that appear cloudy when viewed from any angle when the light control device of a reverse type is energized and in the transparent state.SOLUTION: A light control device provided herein comprises a light control layer and outer support layers sandwiching the light control layer from both sides, and is configured such that the light control layer becomes transparent when current is not applied to the light control layer through the outer support layers and that the light control layer becomes opaque when current is applied to the light control layer through the outer support layers. The light control layer contains a dichroic dye and black spacers, appears black when in the opaque state, exhibits a haze of 14% or less within a viewing angle of 170° when in the transparent state, and has a thickness of 15 μm or less.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[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 has 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 (become transparent) by not exerting their own light-controlling function, and inhibit translucency (become opaque) by exerting their own light-controlling function. Furthermore, reverse-type (reverse mode) light-controlling devices (light-controlling sheets, light-controlling films) are known that are transparent when not energized and opaque when energized. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-144261 Summary of the Invention [Problem to be solved by the invention]

[0005] However, 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 there are areas that appear cloudy when they are in a transparent state when not energized. In particular, when a reverse-type light control device (light control sheet, light control film) is viewed from an angle, the areas that appear cloudy tend 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.

[0006] The present invention was completed based on the above-mentioned awareness of the problems, and aims 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 not powered. [Means for solving the problem]

[0007] 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 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, is black in 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 15 μm or less. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a dimming device and dimming module that can increase transparency when a reverse-type dimming device is in a transparent state when not energized, with few areas that appear cloudy when viewed from any angle. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a first diagram illustrating a configuration example of a light control device. [Figure 2] FIG. 2 is a second diagram illustrating a configuration example of a light control device. [Figure 3] 10A and 10B are diagrams illustrating the difference in the orientation of liquid crystal molecules in a reverse-type light control device when it is in a transparent state when not energized and when it is in an opaque state when energized. [Figure 4] 1 is an SEM image showing the cross-sectional structure of a light-control layer of a reverse-type light-control device in a transparent state when no current is applied. [Figure 5] FIG. 1 is a diagram showing an example of a cross-sectional structure of a light-modulating layer including a dichroic dye and a black spacer. [Figure 6] 10A and 10B are diagrams showing experimental results for demonstrating the superiority of the light control device of the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] <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 to refer to 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 used 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.

[0011] 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.

[0012] In this specification, the 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, zirconium oxide, etc., 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.

[0013] In this specification, a light-controlling device (light-control sheet, light-control film) guarantees light transmittance by not exerting its own light-controlling function (making it transparent), and inhibits light transmittance by exerting its own light-controlling function (making it opaque).

[0014] In this specification, the light control device (light control sheet, light control film) is assumed to be a so-called reverse type (reverse mode) in which 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 the light control device (light control sheet, light control film) is exhibited, this refers to when current is applied in the reverse type, and when the light control function of the light control device (light control sheet, light control film) is not exhibited, this refers to when current is not applied in the reverse type.

[0015] In this way, a 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.

[0016] 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).

[0017] In this specification, the dimming method using the dimming device and dimming module is assumed to be a polymer dispersed liquid crystal (PDLC) method.

[0018] 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 control 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 control 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 control 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 control device (light control sheet, light control film) to the light-transmitting member, and various design modifications are possible.

[0019] 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 interpreted as "upper layer" and "upper support layer," and in this case, the further away from the certain reference (center) layer, the higher the layer is defined, and the closer to the certain reference (center) layer, the lower the layer is defined.

[0020] 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 (%).

[0021] <Conventional technical issues> In recent years, the use of light-controlling films using polymer-dispersed liquid crystals has been increasing. They 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, most 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) to address environmental issues, solar radiation control (light blocking), and design considerations. Furthermore, for automotive applications, there is a growing demand for so-called reverse-type (reverse mode) devices, 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.

[0022] However, 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 they are in a transparent state when not energized. In particular, when a reverse-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, 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.

[0023] <Technical Concept of the Invention> The inventors considered the above problems to be an important technical challenge and proceeded with research and development of a dimming device and dimming module that can increase transparency when viewed from any angle, with fewer areas visible as cloudy white, when the reverse-type dimming device is in its transparent state when not powered, and have thus completed the present invention.

[0024] The present inventors have 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 have 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.

[0025] 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 incorporating a dichroic dye (at least one type of dichroic dye) and black spacers (black functional particles) into the light-controlling layer and setting the film thickness of the light-controlling layer to 15 μm or less, more preferably 5 μm to 10 μm or less, scattered light is absorbed and reduced, thereby reducing whitening caused by scattered light when viewed from an oblique angle, and haze within a viewing angle of 170° in the transparent state can be reduced to 14% or less, more preferably 7% or less. In other words, when a reverse-type light-controlling device (light-controlling sheet, light-controlling film) is in a transparent state when not energized, there are fewer areas that appear cloudy when viewed from any angle, which can achieve the effect of increasing transparency. 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.

[0026] By setting the film thickness of the photochromic layer containing dichroic dye (at least one type of dichroic dye) and black spacers (black functional 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, haze of 14% or less within a viewing angle of 170° in the transparent state).

[0027] The inventors conducted extensive research into the optimal film thickness for a reverse-type, black-colored light-controlling device (light-controlling sheet, light-control film) in a transparent state when not energized, with minimal areas that appear cloudy and high transparency when viewed from any angle. 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 (for example, greater than 15 μm), the number of areas that appear cloudy when a reverse-type, black-colored light-controlling device (light-controlling sheet, light-control film) is in a transparent state when not energized may increase. If the film thickness of the light-controlling layer is too small (for example, 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 may be insufficient. Thus, if the film thickness of the light-controlling layer is inappropriate, it may be 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.

[0028] The light-controlling layer can be a polymer-dispersed liquid crystal layer, and the outer support layer can have a pair of alignment layers positioned on either side of the light-controlling layer, a pair of transparent conductive layers positioned on either side of the pair of alignment layers, and a pair of transparent substrate layers positioned on either side of the pair of transparent conductive layers.

[0029] <Specific embodiment> Hereinafter, embodiments will be described with reference to the drawings. However, the drawings are schematic or conceptual, and the dimensions and proportions of each drawing are not necessarily the same as those of the actual drawing. Furthermore, even when the same parts are shown in different drawings, the dimensional relationships and proportions may be different. In particular, the embodiments shown below are illustrative 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.

[0030] 1 and 2 are first and second diagrams showing a configuration example of a light control device (light control sheet, light control film) 10. FIG. 1 mainly illustrates the layered structure of the light control device 10, and 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 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 light control device 10 may have an adhesive layer for attaching the light control device 10 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.

[0031] 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, negative 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.

[0032] An alignment layer 30X is provided on the outer side of one surface (top surface in the figure) of the light-controlling layer 20, and an alignment layer 30Y is provided on the outer side 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 the 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 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 no driving voltage is applied to the light-controlling layer 20 (functioning as a reverse type (reverse mode)). Examples of materials constituting 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. The alignment treatment for forming the alignment layers 30X and 30Y is, for example, a rubbing treatment, a polarized light irradiation treatment, or a microfabrication treatment.

[0033] A transparent conductive layer 40X is provided on the outer side of one surface (top surface in the figure) of the alignment layer 30X, and a transparent substrate layer 50X is provided on the outer side of the transparent conductive layer 40X. A transparent conductive layer 40Y is provided on the outer side of the other surface (bottom surface in the figure) of the alignment layer 30Y, and a transparent substrate layer 50Y is provided on the outer side of the transparent conductive layer 40Y. As described above, the light control device 10 includes a light control layer 20, a pair of alignment layers 30X and 30Y located on both sides of the light control layer 20, a pair of transparent conductive layers 40X and 40Y located on both sides of the pair of alignment layers 30X and 30Y, and a pair of transparent substrate layers 50X and 50Y located on both sides of the pair of transparent conductive layers 40X and 40Y. Each pair of alignment layers 30X and 30Y, the transparent conductive layers 40X and 40Y, and the transparent substrate layers 50X and 50Y constitutes an "outer support layer" located on both sides of the light control layer 20.

[0034] The transparent conductive layers 40X and 40Y are transparent layers having electrical conductivity. Examples of materials that can be used to form the transparent conductive layers 40X and 40Y 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 50X and 50Y are layers that contain a material such as PET (Polyethylene Terephthalate).

[0035] An additional or alternative layer may be provided as an "outer support layer" located outside the transparent substrate layers 50X and 50Y. In other words, the number and type of "outer support layer" can be freely determined, 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. Examples of the "outer support layer" include a layer for protecting the light-controlling layer 20, the alignment layer 30X and 30Y, the transparent conductive layer 40X and 40Y, and the transparent substrate layers 50X and 50Y; a layer that contributes to controlling the light transmittance of the light-controlling device 10; and a layer that enhances the strength, heat resistance, and other properties of the light-controlling device 10.

[0036] In the example of Fig. 1, the ends (end faces) of the light control device 10 are flush with each other and are aligned with each other without any misalignment when viewed from above. In contrast, in the example of Fig. 2, the ends (end faces) of the light control device 10 are not flush with each other and are aligned with each other so that their positions are misaligned when viewed from above.

[0037] 2, when focusing on the right end (right end face) 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 face) 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.

[0038] 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 supply 80. The wiring section 70X and the wiring section 70Y may be formed, for example, from an FPC (Flexible Printed Circuit) or the like.

[0039] 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.

[0040] 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. As a result, 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.

[0041] On the other hand, when no 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 liquid crystal molecules of the light-controlling device 10 are aligned, with the long axis direction of the liquid crystal molecules aligned along the electric field direction between the transparent conductive layers 40X and 40Y. As a result, light is more easily transmitted through the light-controlling layer 20, and the light-controlling device 10 becomes transparent. In this way, the light-controlling device 10 functions as a reverse type (reverse mode).

[0042] 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. The light control device 10 can also 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.

[0043] 3A and 3B are diagrams showing the difference in the orientation of liquid crystal molecules when the reverse-type light control device 10 is in a transparent state when not energized (powered off) and an opaque state when energized (powered on). FIGS. 3A and 3B are schematic diagrams showing the cross-sectional structure of the light control layer 20. As shown in FIGS. 3A and 3B, liquid crystal molecules of the liquid crystal composition are positioned so as to fill the 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, the liquid crystal molecules of the liquid crystal composition are not positioned in the central portion away from the upper and lower alignment layers 30X and 30Y, and instead form a resin layer.

[0044] As shown in FIG. 3A, 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 vertically in the figure), and the refractive indices 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 act synergistically to absorb and reduce scattered light, thereby reducing whitening caused by scattered light when viewed from an oblique angle. This reduces the haze within a viewing angle of 170° in the transparent state to 14% or less, and 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, resulting in high transparency.

[0045] 3B, 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 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.

[0046] Furthermore, in Figure 1, 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.

[0047] The 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 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 set a small (low) haze within a viewing angle of 170° in the transparent state (for example, 14% or less, more preferably 7% or less). That is, when the reverse-type switchable device 10 is in a transparent state without electricity, there are few areas that appear cloudy when viewed from any angle, and transparency can be increased.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] Figure 4 is a scanning electron microscope (SEM) image (reverse product, liquid crystal layer cross-sectional structure) showing the cross-sectional structure of the switchable layer 20 in the transparent state when the reverse-type light control device 10 is not energized (when the power is off). Although it is not as easy to understand as the schematic diagram in Figure 3, it can be seen that the liquid crystal molecules located inside the switchable layer 20 are oriented in a balanced manner.

[0052] 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.

[0053] In Figure 5, the components included in the light-controlling layer 20 are labeled as follows: the transparent polymer layer is labeled 20P, the gap is labeled 20D, the liquid crystal composition is labeled 20LC, the liquid crystal compound is labeled LCM, the dichroic dye is labeled DD, and the black spacer is labeled SP.

[0054] 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, which is the difference between 1 and ΔL, is * In a plan view opposite to the plane in which the light control device 10 extends, the area occupancy (%) of the black spacers SP in the light control layer 20 is SR. It is preferable that the light control sheet 20 satisfies the following condition 1. (Condition 1) Brightness difference ΔL * The multiplication value of and the area occupancy rate SR satisfies the following. 20≦ΔL * ×SR≦81

[0055] 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 seen by 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.

[0056] 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 of the black spacers SP satisfies the above range, the brightness difference and the area occupancy 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.

[0057] When it is required to further suppress the unevenness of the appearance within the surface of the light control device 10, the lightness difference ΔL * It is preferable that the upper limit of the product of the surface area ratio SR and the surface area ratio SR is small.

[0058] 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) Brightness difference ΔL * However, it is between 20 and 74. (Condition 3) The area occupancy rate SR is 1% or more and 3% or less.

[0059] In the light control 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 control layer 20. * This can enhance the effectiveness of satisfying Condition 1 relating to the multiplication value of and the area occupancy rate SR.

[0060] 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-switching layer 20 may be, for example, 40 mass% or more and 65 mass% or less. That is, the mass M20 of the light-switching layer 20 and the mass MLCM of the liquid crystal compound LCM may satisfy the following formula: The mass M20 of the light-switching 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 spacer SP. 40(mass%)≦(MLCM / M20)×100≦65(mass%)

[0061] The liquid crystal composition 20LC may contain additives such as an antifoaming agent, an antioxidant, a weatherproofing agent, a solvent, a viscosity reducing agent, etc. The weatherproofing agent may be an ultraviolet absorber or a light stabilizer.

[0062] The liquid crystal compound LCM may have negative dielectric anisotropy. When the liquid crystal compound LCM has negative dielectric anisotropy, the dielectric constant ε∥ in the long axis direction of the liquid crystal compound LCM is lower than the dielectric constant ε⊥ in the short axis direction of the liquid crystal compound LCM.

[0063] 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.

[0064] 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 can be obtained. * The smaller the size of the voids 20D in the transparent polymer layer 20P, the more easily light scattering occurs in the light-controlling 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-controlling layer 20, and therefore the second lightness L * 2 tends to decrease.

[0065] 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.

[0066] 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 as well as the outer surface of the black spacer SP is black, 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.

[0067] For example, by changing the color of the black spacer SP from the first color to the second color, the first brightness L of the black spacer 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.

[0068] 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.

[0069] 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 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 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, 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 * This enhances the effectiveness of the multiplication of the area occupancy SR and the area occupancy SR satisfying the above-mentioned range.

[0070] 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 × 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 difference in refractive index 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 areas also have a spherical shape. When the black spacers SP have a columnar shape, the granular regions have a rectangular shape.

[0071] The dichroic dye DD exhibits color (black) when driven by a guest-host mode using a 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 improved 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.

[0072] The dichroic dye DD preferably exhibits black, the same color as the black spacer SP. The dichroic dye DD may exhibit black by one type of compound or a combination of two or more types of compounds.

[0073] 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 brightness L * It is possible to change 2 from the first value to the second value.

[0074] <Numerical examples and demonstration experiments> The inventors 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.

[0075] As shown in FIG. 6, samples according to Examples 1-3 of the present invention and samples according to Comparative Examples 1-4 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 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°). 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°.

[0076] The haze measurement method is as follows. An open-chamber haze meter (BYK haze-garadi) was used. A fixture was installed that could hold the light-adjusting device (dimming 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 dimming device and the line perpendicular to the light source and the light-receiving sensor was defined, and the haze value measured for the dimming 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 was measured using the NDH7000SP manufactured by Nippon Denshoku.

[0077] 6, areas that satisfy the constituent requirements of the light control device of this embodiment, namely, 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, 5 μm or more and 10 μm 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 as clear 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 as gray fill.

[0078] As shown in Figure 6, 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.

[0079] 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 1-3 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 power being applied. Furthermore, the sample of 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 power being applied. Furthermore, the sample of Comparative Example 1-4 does not satisfy the constituent requirement of a haze of 14% or less (especially, 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 power being applied.

[0080] As described above, 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 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.

[0081] 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. [Explanation of symbols]

[0082] 10. Light control devices (light control sheets, light control films) 10X Translucent material (transparent plate, transparent window) 20 Dimming layer (liquid crystal layer) 30X 30Y Orientation layer (outer support layer) 40X 40Y Transparent conductive layer (outer support layer) 50X 50Y Transparent base layer (outer support layer) 60X 60Y Electrode part 70X 70Y Wiring section 80 Drive power supply

Claims

1. The light-controlling layer has outer support layers positioned on both sides of the light-controlling layer, When no current is applied to the photochromic layer through the outer support layer, the photochromic layer is in a transparent state, and when current is applied to the photochromic layer through the outer support layer, the photochromic layer is in an opaque state, the light-controlling layer includes a dichroic pigment and a black spacer, and has a black color in the opaque state; The haze within a viewing angle of 170° in the transparent state is 14% or less, The thickness of the light-controlling layer is 15 μm or less. A light control device characterized by:

2. The haze within a viewing angle of 170° in the transparent state is 7% or less. The light control device according to claim 1 .

3. The thickness of the light-controlling layer is 5 μm or more and 10 μm or less.

3. The light control device according to claim 1 or 2.

4. The light-controlling layer is a polymer dispersed liquid crystal layer.

3. The light control device according to claim 1 or 2.

5. The outer support layer has a pair of alignment layers positioned on both sides of the light-controlling layer, a pair of transparent conductive layers positioned on both sides of the pair of alignment layers, and a pair of transparent substrate layers positioned on both sides of the pair of transparent conductive layers.

3. The light control device according to claim 1 or 2.

6. A light control module having a light-transmitting member and a light control device attached to the light-transmitting member, The light control device includes a light control layer and outer support layers positioned on both sides of the light control layer, When no current is applied to the photochromic layer through the outer support layer, the photochromic layer is in a transparent state, and when current is applied to the photochromic layer through the outer support layer, the photochromic layer is in an opaque state, the light-controlling layer includes a dichroic pigment and a black spacer, and has a black color in the opaque state; The haze within a viewing angle of 170° in the transparent state is 14% or less, The thickness of the light-controlling layer is 15 μm or less. A dimming module characterized by:

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