JP2019168573A - Optical device - Google Patents

Abstract

To provide an optical device that can achieve both heat blocking and lighting when used for a window.SOLUTION: An optical device 1 comprises: a first substrate 10 that has a light transmissivity; a second substrate 20 that is arranged opposite to the first substrate 10 and has light transmissivity; a first electrode layer 40 and a second electrode layer 50 that are arranged opposite to each other between the first substrate 10 and second substrate 20 and has light transmissivity; a first rugged structure layer 31 that is arranged between the first electrode layer 40 and second electrode layer 50; and a variable refractive index layer 32 that is arranged to embed irregularities of the first rugged structure layer 31 and in which the refractive index is changed according to a voltage applied between the first electrode layer 40 and second electrode layer 50. The first rugged structure layer 31 has a retroreflection structure that retroreflects incident light with the irregularities when a difference in refractive index occurs between the first rugged structure layer 31 and variable refractive index layer 32.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical device.

  2. Description of the Related Art Conventionally, a light distribution control device that can change a transmission state of external light such as sunlight incident from the outside is known.

  For example, Patent Document 1 includes a pair of transparent substrates, a pair of transparent electrode layers formed on each of the pair of transparent substrates, and an inclined cross-sectional structure layer and a liquid crystal layer sandwiched between the pair of transparent electrode layers. A liquid crystal optical element is disclosed. In the liquid crystal optical element, the refractive index of the liquid crystal layer is changed by a voltage applied to the pair of transparent electrodes, and the refraction angle of light passing through the interface between the inclined surface of the inclined sectional structure layer and the liquid crystal layer is changed.

JP2015-41006A

  By the way, the window generally requires a daylighting function for taking light into the room. However, when light is introduced indoors, since heat is also introduced, there is a problem that the room temperature rises.

  Therefore, an object of the present invention is to provide an optical device capable of achieving both heat shielding and daylighting when used for a window.

  In order to achieve the above object, an optical device according to one embodiment of the present invention includes a first substrate having a light-transmitting property, a second substrate having a light-transmitting property disposed to face the first substrate, A first electrode layer and a second electrode layer having translucency disposed opposite to each other between the first substrate and the second substrate, and between the first electrode layer and the second electrode layer. The first concavo-convex structure layer and the first concavo-convex structure layer are disposed so as to fill the concavo-convex structure of the first concavo-convex structure layer, and the refractive index changes according to the voltage applied between the first electrode layer and the second electrode layer. The first concavo-convex structure layer includes a retroreflective structure that retroreflects incident light by the concavo-convex when a refractive index difference occurs between the first concavo-convex structure layer and the refractive index variable layer. Have.

  According to the optical device of the present invention, when used for a window, both heat shielding and daylighting can be achieved.

1 is a cross-sectional view of an optical device according to Embodiment 1. FIG. FIG. 3 is an enlarged cross-sectional view showing a part of the optical device according to Embodiment 1 in an enlarged manner. 3 is an enlarged cross-sectional view for explaining a non-application mode (transparent state) of the optical device according to Embodiment 1. FIG. 4 is an enlarged cross-sectional view for explaining a voltage application mode (reflection state) of the optical device according to Embodiment 1. FIG. 6 is a cross-sectional view of an optical device according to Embodiment 2. FIG. FIG. 5 is an enlarged cross-sectional view showing a part of the optical device according to Embodiment 2 in an enlarged manner. 10 is an enlarged cross-sectional view for explaining a non-application mode (transparent state) of the optical device according to Embodiment 2. FIG. 6 is an enlarged cross-sectional view for explaining a first application mode (reflection state) of the optical device according to Embodiment 2. FIG. 10 is an enlarged cross-sectional view for explaining a second application mode (light distribution state) of the optical device according to Embodiment 2. FIG.

  Hereinafter, an optical device according to an embodiment of the present invention will be described in detail with reference to the drawings. Each of the embodiments described below shows a specific example of the present invention. Therefore, numerical values, shapes, materials, components, arrangement and connection forms of components, steps, order of steps, and the like shown in the following embodiments are merely examples, and are not intended to limit the present invention. Therefore, among the constituent elements in the following embodiments, constituent elements that are not described in the independent claims showing the highest concept of the present invention are described as optional constituent elements.

  Each figure is a mimetic diagram and is not necessarily illustrated strictly. Therefore, for example, the scales and the like do not necessarily match in each drawing. Moreover, in each figure, the same code | symbol is attached | subjected about the substantially same structure, The overlapping description is abbreviate | omitted or simplified.

  In addition, in this specification, terms indicating the relationship between elements such as parallel or vertical, terms indicating the shape of an element such as a triangle or trapezoid, and numerical ranges are not expressions expressing only strict meanings. It is an expression that means to include a substantially equivalent range, for example, a difference of about several percent.

  In the present specification and drawings, the x axis, the y axis, and the z axis indicate the three axes of the three-dimensional orthogonal coordinate system. In each embodiment, the z-axis direction is the vertical direction, and the direction perpendicular to the z-axis (the direction parallel to the xy plane) is the horizontal direction. Note that the positive direction of the z-axis is vertically upward. In this specification, “thickness direction” means the thickness direction of the optical device, which is a direction perpendicular to the main surfaces of the first substrate and the second substrate, and “plan view” The time when viewed from the direction perpendicular to the main surface of the first substrate or the second substrate.

(Embodiment 1)
[Overview]
First, an outline of the optical device according to Embodiment 1 will be described with reference to FIGS. 1 and 2.

  FIG. 1 is a cross-sectional view of an optical device 1 according to the present embodiment. FIG. 2 is an enlarged sectional view showing a part of the optical device 1 according to the present embodiment in an enlarged manner, and shows an enlarged region II surrounded by a one-dot chain line in FIG.

  The optical device 1 is a device that controls light incident on the optical device 1. In the present embodiment, the optical device 1 transmits or reflects light incident on the optical device 1.

  As shown in FIGS. 1 and 2, the optical device 1 includes a first substrate 10, a second substrate 20, a light control layer 30, a first electrode layer 40, and a second electrode layer 50.

  Note that an adhesion layer for closely adhering the second electrode layer 50 and the first uneven structure layer 31 of the light control layer 30 may be provided on the surface of the second electrode layer 50 on the light control layer 30 side. . The adhesion layer is, for example, a translucent adhesive sheet or a resin material generally called a primer.

  The optical device 1 has a configuration in which the first electrode layer 40, the light control layer 30, and the second electrode layer 50 are arranged in this order along the thickness direction between the paired first substrate 10 and second substrate 20. It is. In order to maintain the distance between the first substrate 10 and the second substrate 20, a plurality of particulate spacers may be dispersed in the plane, or a columnar structure may be formed.

  The optical device 1 can be realized, for example, as a window with a heat shielding function by being installed on a building window. The optical device 1 is used by being attached to a transparent substrate such as an existing window glass through an adhesive layer, for example. Alternatively, the optical device 1 may be used as a building window itself. For example, the optical device 1 is arranged such that the first substrate 10 is on the outdoor side and the second substrate 20 is on the indoor side.

  In the optical device 1, the refractive index of the refractive index variable layer 32 of the light control layer 30 is changed between the first electrode layer 40 and the second electrode layer 50 by the voltage applied between the first electrode layer 40 and the second electrode layer 50. Varies depending on the voltage applied between them.

  Thereby, a difference in refractive index is generated at the interface between the first uneven structure layer 31 and the refractive index variable layer 32, and light is reflected by the interface. In the present embodiment, at least a part of the light incident on the optical device 1 is retroreflected by reflecting twice at the interface between the first uneven structure layer 31 and the refractive index variable layer 32. That is, the amount of light transmitted through the optical device 1 can be reduced, and the amount of heat taken indoors with the light can be reduced.

  In the present embodiment, the optical device 1 is in a transparent state and a reflective state (specifically, a retroreflective state) according to the magnitude of the voltage applied between the first electrode layer 40 and the second electrode layer 50. And switch.

  Below, each structural member of the optical device 1 is demonstrated in detail with reference to FIG.1 and FIG.2.

[First substrate and second substrate]
The first substrate 10 and the second substrate 20 are base materials having translucency. As the first substrate 10 and the second substrate 20, for example, a glass substrate or a resin substrate can be used.

  Examples of the glass substrate material include soda glass, non-alkali glass, and high refractive index glass. Examples of the material for the resin substrate include resin materials such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate (PC), acrylic (PMMA), and epoxy. The glass substrate has the advantages of high light transmittance and low moisture permeability. On the other hand, the resin substrate has an advantage of less scattering at the time of destruction.

  The first substrate 10 and the second substrate 20 may be composed of the same material, or may be composed of different materials. Moreover, the 1st board | substrate 10 and the 2nd board | substrate 20 are not restricted to a rigid board | substrate, The flexible board | substrate which has flexibility may be sufficient. In the present embodiment, the first substrate 10 and the second substrate 20 are transparent resin substrates made of PET resin.

  The second substrate 20 is a counter substrate facing the first substrate 10, and is disposed at a position facing the first substrate 10. The first substrate 10 and the second substrate 20 are arranged in parallel with a predetermined distance of, for example, 1 μm to 1000 μm. The 1st board | substrate 10 and the 2nd board | substrate 20 are adhere | attached by sealing resin, such as the adhesive agent formed in the frame shape at the edge part of each other.

  The plan view shape of the first substrate 10 and the second substrate 20 is, for example, a rectangular shape such as a square or a rectangle, but is not limited thereto, and may be a polygon other than a circle or a rectangle, Any shape can be employed.

[Light control layer]
The light control layer 30 is disposed between the first electrode layer 40 and the second electrode layer 50 as shown in FIGS. 1 and 2. The light control layer 30 can change the optical state between a transparent state and a reflective state.

  The light control layer 30 includes a first uneven structure layer 31 and a refractive index variable layer 32. In the present embodiment, the light control layer 30 is incident from the first substrate 10 side when light is retroreflected at the interface between the first uneven structure layer 31 and the refractive index variable layer 32 in the reflective state. The emitted light can be emitted from the first substrate 10 side. The light control layer 30 transmits light incident on the light control layer 30 as it is in the transparent state.

[First uneven structure layer]
The first concavo-convex structure layer 31 is a finely shaped layer provided to make the surface (interface) of the refractive index variable layer 32 uneven. Specifically, the first uneven structure layer 31 is an uneven structure having micro-order size unevenness.

  The first concavo-convex structure layer 31 has a retroreflective structure that retroreflects incident light when a refractive index difference occurs with the refractive index variable layer 32. In the present embodiment, the retroreflective structure is a prism structure. The retroreflective structure may be a bead structure.

  Specifically, the first concavo-convex structure layer 31 includes a plurality of convex portions 33 and a plurality of concave portions 34 as shown in FIG. In the example shown in FIG. 2, although the some convex part 33 has shown the example connected at the root, you may isolate | separate individually. In addition, for example, a layer (film) -like base portion serving as a base for the plurality of protrusions 33 may be provided between the plurality of protrusions 33 and the second electrode layer 50.

  Each of the plurality of recesses 34 has the same shape and size. The plurality of concave portions 34 are prism-shaped concave portions that retroreflect incident light. For example, each of the plurality of recesses 34 is a regular tetrahedral recess. For example, one surface of the regular tetrahedron corresponds to the opening surface of the concave portion 34 on the first electrode layer 40 side, and the remaining three surfaces correspond to the side surfaces of the convex portion 33 constituting the concave portion 34. The shape of the recess 34 is not particularly limited as long as it is a shape that retroreflects incident light.

  The plurality of recesses 34 are provided side by side in the plane when the second substrate 20 is viewed in plan. For example, the plurality of recesses 34 may be randomly distributed and may be regularly arranged in a matrix. The plurality of recesses 34 may be provided so as to be planarly filled in a plan view. Thereby, substantially all of the incident light can be retroreflected.

  Each of the plurality of recesses 34 is provided so as to be filled with the refractive index variable layer 32. As a result, when a difference in refractive index occurs at the interface between the recess 34 and the refractive index variable layer 32, the incident light is retroreflected by reflecting light multiple times at the interface.

  The depth (length in the z-axis direction) of the plurality of recesses 34 is, for example, 5 μm to 50 μm, and preferably 10 μm, but is not limited thereto. Moreover, although the space | interval of the two adjacent recessed parts 34, ie, the width | variety of the convex part 33, is 0 micrometer-100 micrometers, it is not restricted to this.

  As a material of the first concavo-convex structure layer 31, for example, a resin material having optical transparency such as an acrylic resin, an epoxy resin, or a silicone resin can be used. The first concavo-convex structure layer 31 is formed of, for example, an ultraviolet curable resin material, and can be formed by molding or nanoimprinting. For example, the first concavo-convex structure layer 31 can form a concavo-convex structure having a trapezoidal cross section by mold pressing using an acrylic resin having a refractive index of 1.5 with respect to green light.

[Refractive index variable layer]
The refractive index variable layer 32 is disposed so as to fill the plurality of recesses 34. Specifically, the refractive index variable layer 32 is disposed so as to fill a gap formed between the first electrode layer 40 and the second electrode layer 50. As shown in FIG. 2, when the tip portion of the convex portion 33 and the second electrode layer 50 are separated from each other, the refractive index variable layer 32 is not limited to the concave portion 34 but the tip portion of the convex portion 33 and the second electrode layer 50. It arrange | positions so that the clearance gap between the 2 electrode layers 50 may be filled.

  The refractive index of the refractive index variable layer 32 changes depending on the voltage applied between the first electrode layer 40 and the second electrode layer 50. Specifically, the refractive index variable layer 32 functions as a refractive index adjustment layer capable of adjusting the refractive index in the visible light band when a voltage is applied between the electrodes. For example, a DC voltage is applied between the first electrode layer 40 and the second electrode layer 50 by a control device (not shown) or the like.

  As shown in FIG. 2, the refractive index variable layer 32 includes an insulating liquid 35 and nanoparticles 36 contained in the insulating liquid 35. The refractive index variable layer 32 is a nanoparticle dispersion layer in which countless nanoparticles 36 are dispersed in the insulating liquid 35.

  The insulating liquid 35 is a transparent liquid having insulating properties, and is a solvent serving as a dispersion medium in which the nanoparticles 36 are dispersed as a dispersoid. As the insulating liquid 35, for example, a material having a refractive index (solvent refractive index) of about 1.3 to about 1.6 can be used. In the present embodiment, the insulating liquid 35 having a refractive index of about 1.4 is used.

The kinematic viscosity of the insulating liquid 35 is preferably about 100 mm ² / s. Further, the insulating liquid 35 has a low dielectric constant (for example, less than the dielectric constant of the first uneven structure layer 31), non-flammability (for example, a high flash point having a flash point of 250 ° C. or higher), and low volatility. May be. Specifically, the insulating liquid 35 is a hydrocarbon such as an aliphatic hydrocarbon, naphtha, and other petroleum solvents, a low molecular weight halogen-containing polymer, or a mixture thereof. As an example, the insulating liquid 35 is a halogenated hydrocarbon such as a fluorinated hydrocarbon. As the insulating liquid 35, silicone oil or the like can be used.

  A plurality of nanoparticles 36 are dispersed in the insulating liquid 35. The nanoparticles 36 are fine particles having a particle size of nano-order size. Specifically, when the wavelength of incident light is λ, the particle size of the nanoparticles 36 is preferably λ / 4 or less. By setting the particle size of the nanoparticles 36 to λ / 4 or less, light scattering by the nanoparticles 36 can be reduced, and an average refractive index of the nanoparticles 36 and the insulating liquid 35 can be obtained. The particle diameter of the nanoparticles 36 is preferably as small as possible, preferably 100 nm or less, more preferably several nm to several tens nm.

  The nanoparticles 36 are made of, for example, a high refractive index material. Specifically, the refractive index of the nanoparticles 36 is higher than the refractive index of the insulating liquid 35. In the present embodiment, the refractive index of the nanoparticles 36 is higher than the refractive index of the first uneven structure layer 31.

As the nanoparticle 36, for example, metal oxide fine particles can be used. The nanoparticles 36 may be made of a material having a high transmittance. In the present embodiment, transparent zirconia particles having a refractive index of 2.1 composed of zirconium oxide (ZrO ₂ ) are used as the nanoparticles 36. The nanoparticles 36 are not limited to zirconium oxide, and may be composed of titanium oxide (TiO ₂ : refractive index 2.5) or the like.

  The nanoparticles 36 are charged charged particles. For example, by modifying the surface of the nanoparticles 36, the nanoparticles 36 can be charged positively (plus) or negatively (minus). In the present embodiment, the nanoparticles 36 are positively (plus) charged.

  In the refractive index variable layer 32 configured as described above, the charged nanoparticles 36 are dispersed throughout the insulating liquid 35. In this embodiment, as an example, zirconia particles having a refractive index of 2.1 are used as the nanoparticles 36 and dispersed in the insulating liquid 35 having a solvent refractive index of about 1.4 are used as the refractive index variable layer 32. It is said.

  Further, the overall refractive index (average refractive index) of the refractive index variable layer 32 is substantially the same as the refractive index of the first concavo-convex structure layer 31 in a state where the nanoparticles 36 are uniformly dispersed in the insulating liquid 35. It is set and is about 1.5 in the present embodiment. The overall refractive index of the refractive index variable layer 32 can be changed by adjusting the concentration (amount) of the nanoparticles 36 dispersed in the insulating liquid 35. Although details will be described later, the amount of the nanoparticles 36 is, for example, such that it is buried in the recesses 34 of the first uneven structure layer 31. In this case, the concentration of the nanoparticles 36 with respect to the insulating liquid 35 is about 10% to about 30%.

  Since the nanoparticles 36 dispersed in the insulating liquid 35 are charged, when a voltage is applied between the first electrode layer 40 and the second electrode layer 50, the nanoparticles 36 have a polarity with which the nanoparticles 36 are charged. It migrates in the insulating liquid 35 so as to be attracted to the electrode layer having a polarity different from that of the electrode layer and is unevenly distributed in the insulating liquid 35. In the present embodiment, since the nanoparticles 36 are positively charged, they are attracted to the negative electrode layer of the first electrode layer 40 and the second electrode layer 50.

  As a result, the particle distribution of the nanoparticles 36 in the refractive index variable layer 32 can be changed to give the concentration distribution of the nanoparticles 36 in the refractive index variable layer 32, so that the refractive index in the refractive index variable layer 32 can be obtained. Distribution changes. That is, the refractive index of the refractive index variable layer 32 partially changes. Thus, the refractive index variable layer 32 mainly functions as a refractive index adjustment layer that can adjust the refractive index for light in the visible light band.

  For example, according to the present embodiment, the refractive index of at least a part of the refractive index variable layer 32 (specifically, the first region 32a shown in FIG. 3B) is the refractive index of the first uneven structure layer 31. The refractive index can be changed to a refractive index of 0.3 or more. Thereby, retroreflection of light can be generated.

  The refractive index variable layer 32 includes, for example, end portions of the first substrate 10 on which the first electrode layer 40 is formed and the second substrate 20 on which the second electrode layer 50 and the first uneven structure layer 31 are formed. It is formed by injecting a refractive index variable material by a vacuum injection method with the outer periphery sealed with a sealing resin. Alternatively, the refractive index variable layer 32 may be formed by dropping the refractive index variable material onto the second electrode layer 50 and the first concavo-convex structure layer 31 of the second substrate 20 and then forming the first electrode layer 40 on the first substrate 10. May be formed by bonding. In the present embodiment, the refractive index variable material is an insulating liquid 35 in which nanoparticles 36 are dispersed. The insulating liquid 35 in which the nanoparticles 36 are dispersed is sealed between the first substrate 10 and the second substrate 20. The thickness of the refractive index variable layer 32 is, for example, 1 μm to 1000 μm, but is not limited thereto.

[First electrode layer and second electrode layer]
As shown in FIGS. 1 and 2, the first electrode layer 40 and the second electrode layer 50 are electrically paired. The first electrode layer 40 and the second electrode layer 50 are paired not only electrically but also in arrangement, and are arranged between the first substrate 10 and the second substrate 20 so as to face each other. ing. Specifically, the first electrode layer 40 and the second electrode layer 50 are disposed so as to sandwich the light control layer 30.

  The first electrode layer 40 and the second electrode layer 50 have translucency and transmit incident light. The first electrode layer 40 and the second electrode layer 50 are, for example, transparent conductive layers. As a material of the transparent conductive layer, a conductor-containing resin made of a resin containing a conductor such as a transparent metal oxide such as ITO (Indium Tin Oxide) or IZO (Indium Zinc Oxide), silver nanowires or conductive particles, or A metal thin film such as a silver thin film can be used. In addition, the 1st electrode layer 40 and the 2nd electrode layer 50 may be these single layer structures, and these laminated structures (for example, laminated structure of a transparent metal oxide and a metal thin film) may be sufficient as them. In the present embodiment, each of the first electrode layer 40 and the second electrode layer 50 is ITO having a thickness of 100 nm.

  The first electrode layer 40 is disposed between the first substrate 10 and the refractive index variable layer 32. Specifically, the first electrode layer 40 is formed on the surface of the first substrate 10 on the light control layer 30 side.

  On the other hand, the second electrode layer 50 is disposed between the first uneven structure layer 31 and the second substrate 20. Specifically, the second electrode layer 50 is formed on the surface of the second substrate 20 on the light control layer 30 side.

  In addition, the 1st electrode layer 40 and the 2nd electrode layer 50 are comprised so that electrical connection with an external power supply is attained, for example. For example, electrode pads or the like for connecting to an external power source may be formed on the first substrate 10 and the second substrate 20 by being drawn from each of the first electrode layer 40 and the second electrode layer 50.

  Each of the first electrode layer 40 and the second electrode layer 50 is formed by forming a conductive film such as ITO by, for example, vapor deposition or sputtering.

[Operation and optical state of optical device]
Next, the operation and optical state of the optical device 1 will be described. The optical device 1 according to the present embodiment can switch between a transparent state and a reflective state according to a voltage applied between the first electrode layer 40 and the second electrode layer 50.

<Transparent state (non-application mode)>
FIG. 3A is an enlarged cross-sectional view for explaining a non-application mode (transparent state) of the optical device 1 according to the present embodiment. In FIG. 3A, the path of the light L incident obliquely on the optical device 1 is indicated by a thick arrow.

  In FIG. 3A, no voltage is applied between the first electrode layer 40 and the second electrode layer 50. Specifically, the first electrode layer 40 and the second electrode layer 50 are equipotential with each other. In this case, since the nanoparticles 36 are not attracted to any electrode layer, the nanoparticles 36 are dispersed throughout the insulating liquid 35.

  In the present embodiment, as described above, the refractive index of the refractive index variable layer 32 in a state where the nanoparticles 36 are dispersed throughout the insulating liquid 35 is about 1.5. Moreover, the refractive index of the convex part 33 of the 1st uneven structure layer 31 is about 1.5. That is, the plurality of convex portions 33 and the refractive index variable layer 32 have the same refractive index. Therefore, the refractive index is uniform throughout the light control layer 30.

  For this reason, as shown in FIG. 3A, when the light L is incident from obliquely upward to obliquely downward, there is no refractive index difference at the interface between the refractive index variable layer 32 and the first concavo-convex structure layer 31. The light travels straight. That is, in the yz section, the incident angle and the exit angle of the light L are substantially the same.

  Thus, the optical device 1 is in a transparent state that allows the incident light to pass through substantially as it is (without changing the traveling direction).

  The light L is actually incident on the first substrate 10, emitted from the second substrate 20, passed through the interface between the first substrate 10 and the first electrode layer 40, and the second Although it is refracted when the passing medium changes, such as when passing through the interface between the electrode layer 50 and the second substrate 20, it is not shown in FIG. 3A. The same applies to FIG. 3B and FIGS. 6A to 6C described later.

<Reflection state (voltage application mode)>
FIG. 3B is an enlarged cross-sectional view for explaining a voltage application mode (reflection state) of the optical device 1 according to the present embodiment. In FIG. 3B, the path of the light L incident obliquely on the optical device 1 is indicated by a thick arrow.

  In FIG. 3B, a predetermined voltage is applied between the first electrode layer 40 and the second electrode layer 50. For example, a voltage having a potential difference of about several tens of volts is applied to the first electrode layer 40 and the second electrode layer 50. Thereby, in the refractive index variable layer 32, the charged nanoparticles 36 migrate in the insulating liquid 35 so as to be attracted to the electrode layer having a polarity different from the polarity of the nanoparticles 36. That is, the nanoparticles 36 are electrophoresed in the insulating liquid 35.

  In the example illustrated in FIG. 3B, the second electrode layer 50 has a lower potential than the first electrode layer 40. For this reason, the positively charged nanoparticles 36 migrate toward the second electrode layer 50, enter the concave portion 34 of the first concave-convex structure layer 31, and accumulate.

  As described above, the nanoparticles 36 are unevenly distributed on the first uneven structure layer 31 side in the refractive index variable layer 32, whereby the particle distribution of the nanoparticles 36 is changed, and the refractive index distribution in the refractive index variable layer 32 is uniform. It is not like. Specifically, as shown in FIG. 3B, a concentration distribution of the nanoparticles 36 is formed in the refractive index variable layer 32.

  For example, the concentration of the nanoparticles 36 is high in the first region 32a on the first uneven structure layer 31 side, and the concentration of the nanoparticles 36 is low in the second region 32b on the first electrode layer 40 side. Accordingly, a difference in refractive index occurs between the first region 32a and the second region 32b.

  In the present embodiment, the refractive index of the nanoparticles 36 is higher than the refractive index of the insulating liquid 35. Therefore, the refractive index of the first region 32a where the concentration of the nanoparticles 36 is high is higher than the refractive index of the second region 32b where the concentration of the nanoparticles 36 is low, that is, the proportion of the insulating liquid 35 is large. For example, the refractive index of the first region 32a is greater than about 1.5 to about 1.9 depending on the concentration of the nanoparticles 36. The refractive index of the second region 32b becomes a value less than about 1.4 to less than about 1.5 depending on the concentration of the nanoparticles 36.

  Here, the inventors of the present application examined a difference in refractive index necessary for retroreflection by the first concavo-convex structure layer 31 by performing a simulation. As a result, when the refractive index difference was 0.2, there was little light retroreflected, and there was also light transmitted through the light control layer 30 to the second substrate 20 side. On the other hand, when the refractive index difference was 0.3, most of the light could be retroreflected.

  Therefore, in the present embodiment, by applying a voltage between the first electrode layer 40 and the second electrode layer 50, the refractive index of the first region 32a of the refractive index variable layer 32 and the refraction of the first concavo-convex structure layer 31 are applied. The difference from the rate may be 0.3 or more. Thereby, light can be retroreflected at the interface between the first region 32 a and the first uneven structure layer 31. In addition, even if it is a case where a refractive index difference is smaller than 0.3, the shape of the unevenness | corrugation of the 1st uneven structure layer 31 may be adjusted suitably so that a retroreflection may generate | occur | produce.

  In the present embodiment, since the refractive index of the plurality of convex portions 33 is about 1.5, by applying a voltage between the first electrode layer 40 and the second electrode layer 50, the first region 32a The refractive index is set to 1.8 or more. For example, the refractive index of the first region 32a is 1.9. For this reason, as shown in FIG. 3B, when the light L is incident from an oblique direction, the incident light L is retroreflected at the interface between the first region 32 a and the convex portion 33.

  Thereby, as shown in FIG. 3B, the light L is emitted from the first substrate 10. That is, since the light L is not emitted indoors from the second substrate 20, the amount of heat taken indoors can be suppressed.

  As described above, when a predetermined voltage is applied between the first electrode layer 40 and the second electrode layer 50, there is a difference in refractive index at the interface between each of the plurality of convex portions 33 and the refractive index variable layer 32. Light generated and incident on the light control layer 30 is retroreflected. That is, the optical device 1 enters a retroreflection state in which incident light is retroreflected.

[Effects, etc.]
As described above, the optical device 1 according to the present embodiment includes the first substrate 10 having translucency, the second substrate 20 having translucency, which is disposed to face the first substrate 10, and The first electrode layer 40 and the second electrode layer 50 having translucency, which are disposed to face each other between the first substrate 10 and the second substrate 20, and the first electrode layer 40 and the second electrode layer 50, The first concavo-convex structure layer 31 disposed between the first concavo-convex structure layer 31 and the first concavo-convex structure layer 31 so as to fill the concavo-convex structure, and refracted according to the voltage applied between the first electrode layer 40 and the second electrode layer 50. And a refractive index variable layer 32 having a variable rate. The first concavo-convex structure layer 31 has a retroreflective structure that retroreflects incident light by concavo-convex when a refractive index difference is generated between the first concavo-convex structure layer 31 and the refractive index variable layer 32.

  Thereby, since the 1st uneven structure layer 31 has a retroreflection structure, the light which injects from the 1st board | substrate 10 side can be radiate | emitted to the 1st board | substrate 10 side. That is, the optical device 1 can suppress the amount of transmitted light, and can suppress the amount of heat taken indoors when used in a window.

  Further, by changing the refractive index of the refractive index variable layer 32, the refractive index difference between the first uneven structure layer 31 and the refractive index variable layer 32 can be made substantially zero. In this case, since light is not reflected at the interface between the first concavo-convex structure layer 31 and the refractive index variable layer 32, the light passes through the optical device 1 as it is. That is, the optical device 1 can introduce light indoors when it is used for a window.

  Thus, the optical device 1 can switch between the transparent state and the reflective state by changing the refractive index of the refractive index variable layer 32. For example, since the optical state of the optical device 1 can be changed based on the user's preference or the season or time zone, the optical device 1 is compatible with both heat shielding and daylighting when used for a window. can do.

  Further, for example, the refractive index of the refractive index variable layer 32 can be changed to a refractive index at which the refractive index difference from the first uneven structure layer 31 is 0.3 or more.

  Thereby, the light is totally reflected at the interface between the refractive index variable layer 32 and the first uneven structure layer 31, and therefore, the light can be retroreflected by being reflected a plurality of times.

  Further, for example, the height of the unevenness of the first uneven structure layer 31 is not less than 5 μm and not more than 50 μm.

  As a result, a large light reflection surface can be secured, and the amount of retroreflected light can be increased.

  For example, the retroreflective structure is a prism structure or a bead structure.

  Thereby, light can be easily retroreflected.

  For example, the refractive index of the refractive index variable layer 32 can be changed to a refractive index substantially the same as the refractive index of the first uneven structure layer 31.

  As a result, the refractive index difference between the refractive index variable layer 32 and the first concavo-convex structure layer 31 can be made substantially zero, so that at the interface between the refractive index variable layer 32 and the first concavo-convex structure layer 31. Light reflection and refraction hardly occur. Therefore, the optical device 1 can be made into a transparent state, and it can light efficiently.

  Further, for example, the refractive index variable layer 32 includes an insulating liquid 35 and a plurality of charged nanoparticles 36 dispersed in the insulating liquid 35 having a refractive index different from that of the insulating liquid 35.

  Accordingly, the refractive index of the refractive index variable layer 32 changes according to the degree of aggregation of the charged nanoparticles 36 dispersed in the insulating liquid 35. The degree of aggregation of the nanoparticles 36 can be easily changed according to the voltage applied between the first electrode layer 40 and the second electrode layer 50. Therefore, the transparent state and the reflection state can be easily changed. Further, in the reflection state, the refractive index difference can be affected by both P-polarized light and S-polarized light, so that the reflectance can be increased.

(Embodiment 2)
Next, the second embodiment will be described. In the following description, differences from the first embodiment will be mainly described, and description of common points will be omitted or simplified.

  FIG. 4 is a cross-sectional view of the optical device 101 according to the present embodiment. FIG. 5 is an enlarged cross-sectional view showing a part of the optical device 101 according to the present embodiment in an enlarged manner, and shows an enlarged region V surrounded by a one-dot chain line in FIG.

  As shown in FIGS. 4 and 5, the optical device 101 is different from the optical device 1 according to Embodiment 1 in that the optical device 101 includes a light control layer 130 instead of the light control layer 30. The light control layer 130 includes not only the first uneven structure layer 31 and the refractive index variable layer 32 but also the second uneven structure layer 131.

  In the present embodiment, the optical device 101 can distribute light by causing the second uneven structure layer 131 to totally reflect light. That is, the optical device 101 can be emitted from the second substrate 20 by bending the traveling direction of light incident from the first substrate 10.

  The second concavo-convex structure layer 131 is a finely shaped layer provided to make the surface (interface) of the refractive index variable layer 32 uneven. As shown in FIG. 5, the second concavo-convex structure layer 131 has a plurality of convex portions 133 and a plurality of concave portions 134.

  Specifically, the second concavo-convex structure layer 131 is a concavo-convex structure formed by a plurality of convex portions 133 having a micro-order size. Between the plurality of convex portions 133 are a plurality of concave portions 134. That is, one concave portion 134 is between two adjacent convex portions 133. In the example shown in FIG. 5, an example in which a plurality of convex portions 133 are connected at the root is shown, but they may be separated individually. In addition, for example, a layer (film) -shaped base portion serving as a base of the convex portion 133 may be provided between the plurality of convex portions 133 and the first electrode layer 40.

  The plurality of protrusions 133 are a plurality of protrusions arranged side by side in the z-axis direction parallel to the main surface of the first substrate 10 (the surface on which the first electrode layer 40 is provided). That is, in the present embodiment, the z-axis direction is an arrangement direction of the plurality of convex portions 133.

  In the present embodiment, the plurality of convex portions 133 are long convex shapes extending in a direction orthogonal to the arrangement direction. Specifically, the plurality of convex portions 133 are formed in a stripe shape extending in the x-axis direction. Each of the plurality of convex portions 133 extends linearly along the x-axis direction. For example, each of the plurality of convex portions 133 is a triangular prism that is disposed sideways with respect to the first electrode layer 40.

  As shown in FIG. 5, each of the plurality of convex portions 133 has a shape that tapers from the root to the tip. Specifically, the cross-sectional shape of each of the plurality of convex portions 133 is a tapered shape that tapers along the direction from the first substrate 10 toward the second substrate 20. In the present embodiment, the cross-sectional shape of the convex portion 133 in the yz cross section is a substantially triangular shape that tapers along the thickness direction of the optical device 101, but is not limited thereto. The cross-sectional shape of the convex portion 133 may be a substantially trapezoidal shape, other polygons, or a polygon including a curve. The shapes of the plurality of convex portions 133 are the same as each other, but may be different.

  Note that the substantially trapezoidal or triangular shape includes a trapezoidal or triangular shape with rounded vertices. In addition, the substantially trapezoidal shape or the substantially triangular shape includes a case where each side is not completely straight, for example, a case where the side is slightly bent with a displacement of about several percent of the length of each side, or a minute unevenness. Cases are also included.

  In the present embodiment, as shown in FIG. 5, each of the plurality of convex portions 133 has a first side surface 133a and a second side surface 133b. The first side surface 133a and the second side surface 133b are surfaces that intersect the z-axis direction. Each of the first side surface 133a and the second side surface 133b is an inclined surface that is inclined at a predetermined inclination angle with respect to the y-axis direction. The distance between the first side surface 133 a and the second side surface 133 b, that is, the width of the convex portion 133 gradually decreases from the first substrate 10 toward the second substrate 20.

  For example, when the optical device 101 is arranged so that the z axis coincides with the vertical direction, the first side surface 133a is a side surface facing the vertically lower side among the plurality of side surfaces constituting the convex portion 133. The first side surface 133a is a refracting surface that refracts incident light.

  For example, when the optical device 101 is arranged so that the z-axis coincides with the vertical direction, the second side surface 133b is a side surface facing the vertically upper side among the plurality of side surfaces constituting the convex portion 133. The second side surface 133b is a reflecting surface that reflects incident light. The reflection here is total reflection, and the second side surface 133b functions as a total reflection surface.

  The inclination angle of the first side surface 133a and the inclination angle of the second side surface 133b are, for example, in the range of 0 ° to 25 °. In other words, the two base angles of the substantially trapezoidal shape or the substantially triangular shape that are the cross-sectional shape of the convex portion 133 are 65 ° or more and 90 ° or less, respectively. Alternatively, at least one of the two base angles may be smaller than 65 °. The inclination angle of the first side surface 133a and the inclination angle of the second side surface 133b may be different from each other or may be equal.

  The width (length in the z-axis direction) of the plurality of convex portions 133 is, for example, 1 μm to 20 μm, and preferably 10 μm or less, but is not limited thereto. Moreover, although the space | interval of the adjacent 2 convex part 133 is 0 micrometer-100 micrometers, for example, it is not restricted to this.

  As a material of the second concavo-convex structure layer 131, for example, a resin material having optical transparency such as an acrylic resin, an epoxy resin, or a silicone resin can be used. The second uneven structure layer 131 is formed of, for example, an ultraviolet curable resin material, and can be formed by molding or nanoimprinting. For example, the second concavo-convex structure layer 131 can form a concavo-convex structure with a trapezoidal cross section by mold pressing using an acrylic resin having a refractive index of 1.5 for green light. In the present embodiment, the refractive index of the second uneven structure layer 131 and the refractive index of the first uneven structure layer 31 are, for example, the same.

  The plurality of protrusions 133 may extend while meandering along the x-axis direction. For example, the plurality of convex portions 133 may be formed in a wavy stripe shape.

  Further, an adhesive layer made of a translucent adhesive sheet or a resin material generally called a primer may be provided between the second uneven structure layer 131 and the first electrode layer 40. Good.

[Operation and optical state of optical device]
Next, the operation and optical state of the optical device 101 will be described. The optical device 101 according to the present embodiment can switch between a transparent state, a reflective state, and a light distribution state according to a voltage applied between the first electrode layer 40 and the second electrode layer 50.

<Transparent state (non-application mode)>
FIG. 6A is an enlarged cross-sectional view for explaining a non-application mode (transparent state) of the optical device 101 according to the present embodiment. In FIG. 6A, the path of the light L incident obliquely on the optical device 101 is indicated by a thick arrow.

  In FIG. 6A, no voltage is applied between the first electrode layer 40 and the second electrode layer 50. Specifically, the first electrode layer 40 and the second electrode layer 50 are equipotential with each other. In this case, since the nanoparticles 36 are not attracted to any electrode layer, the nanoparticles 36 are dispersed throughout the insulating liquid 35.

  In the present embodiment, as described above, the refractive index of the refractive index variable layer 32 in a state where the nanoparticles 36 are dispersed throughout the insulating liquid 35 is about 1.5. Moreover, the refractive index of the convex part 33 of the 1st uneven structure layer 31 and the refractive index of the convex part 133 of the 2nd uneven structure layer 131 are about 1.5. That is, the plurality of convex portions 33 and the plurality of convex portions 133 and the refractive index variable layer 32 have the same refractive index. Therefore, the refractive index is uniform throughout the light control layer 130.

  For this reason, as shown in FIG. 6A, when light L is incident from obliquely upward to obliquely downward, the interface between the second uneven structure layer 131 and the refractive index variable layer 32, and the refractive index variable layer 32 Since there is no difference in refractive index at the interface with the first concavo-convex structure layer 31, the light travels straight. That is, in the yz section, the incident angle and the exit angle of the light L are substantially the same.

  As described above, the optical device 101 is in a transparent state in which incident light is transmitted substantially as it is (without changing the traveling direction).

<Reflection state (first application mode)>
FIG. 6B is an enlarged cross-sectional view for explaining the first application mode (reflection state) of the optical device 101 according to the present embodiment. In FIG. 6B, the path of the light L incident obliquely on the optical device 101 is indicated by a thick arrow.

  6B, a predetermined voltage is applied between the first electrode layer 40 and the second electrode layer 50, as in the voltage application mode according to Embodiment 1 (see FIG. 3B). For example, a voltage having a potential difference of about several tens of volts is applied to the first electrode layer 40 and the second electrode layer 50. Specifically, as shown in FIG. 6B, the second electrode layer 50 has a lower potential than the first electrode layer 40. For this reason, the positively charged nanoparticles 36 migrate toward the second electrode layer 50, enter the concave portion 34 of the first concave-convex structure layer 31, and accumulate.

  In the present embodiment, since the second concavo-convex structure layer 131 is provided on the first substrate 10 side, light is reflected by the difference in refractive index between the second concavo-convex structure layer 131 and the second region 32b of the refractive index variable layer 32. L is refracted. For example, as shown in FIG. 6B, the light L travels toward the first concavo-convex structure layer 31 after being refracted by the first side surface 133a.

  In the first concavo-convex structure layer 31, as in the voltage application mode according to the first embodiment, the light L is retroreflected due to the difference in refractive index between the first region 32a and the convex portion 33, toward the first side surface 133a. Return. The light L returning to the first side surface 133a is refracted by the first side surface 133a and is emitted from the first substrate 10 side.

  As described above, as illustrated in FIG. 6B, the light L is emitted from the first substrate 10. That is, since the light L is not emitted indoors from the second substrate 20, the amount of heat taken indoors can be suppressed.

  As described above, when a predetermined voltage is applied between the first electrode layer 40 and the second electrode layer 50, there is a difference in refractive index at the interface between each of the plurality of convex portions 33 and the refractive index variable layer 32. Light generated and incident on the light control layer 30 is retroreflected. That is, the optical device 101 enters a retroreflective state in which incident light is retroreflected.

  In addition, this inventor examined the refractive index difference required in order to carry out retroreflection by the 1st uneven structure layer 31 when the 2nd uneven structure layer 131 was provided by performing simulation. As a result, similarly to the case where the second concavo-convex structure layer 131 is not provided, when the difference in refractive index is 0.2, the light that is retroreflected is little and the light control layer 130 is disposed on the second substrate 20 side. There was also light passing through. On the other hand, when the refractive index difference was 0.3, most of the light could be retroreflected.

  Therefore, also in the present embodiment, by applying a voltage between the first electrode layer 40 and the second electrode layer 50, the refractive index of the first region 32a of the refractive index variable layer 32 and the first uneven structure layer 31 can be reduced. What is necessary is just to make the difference with a refractive index 0.3 or more. Thereby, light can be retroreflected at the interface between the first region 32 a and the first uneven structure layer 31. In addition, even if it is a case where a refractive index difference is smaller than 0.3, the shape of the unevenness | corrugation of the 1st uneven structure layer 31 may be adjusted suitably so that a retroreflection may generate | occur | produce.

<Light distribution state (second application mode)>
FIG. 6C is an enlarged cross-sectional view for explaining the second application mode (light distribution state) of the optical device 101 according to the present embodiment. In FIG. 6C, the path of the light L incident obliquely on the optical device 101 is indicated by a thick arrow.

  In FIG. 6C, a predetermined voltage is applied between the first electrode layer 40 and the second electrode layer 50. For example, a voltage having a potential difference of about several tens of volts is applied to the first electrode layer 40 and the second electrode layer 50. In the second application mode, the polarity of the voltage applied between the first electrode layer 40 and the second electrode layer 50 is different from that in the first application mode.

  Specifically, as shown in FIG. 6C, the second electrode layer 50 is at a higher potential than the first electrode layer 40. For this reason, the positively charged nanoparticles 36 migrate toward the first electrode layer 40 and enter and accumulate in the recesses 134 of the second uneven structure layer 131.

  Accordingly, the concentration of the nanoparticles 36 is increased in the first region 32a on the second uneven structure layer 131 side, and the concentration of the nanoparticles 36 is decreased in the second region 32b on the second electrode layer 50 side. Accordingly, a difference in refractive index occurs between the first region 32a and the second region 32b.

  In the present embodiment, the refractive index of the nanoparticles 36 is higher than the refractive index of the insulating liquid 35. Therefore, the refractive index of the first region 32a where the concentration of the nanoparticles 36 is high is higher than the refractive index of the second region 32b where the concentration of the nanoparticles 36 is low, that is, the proportion of the insulating liquid 35 is large. For example, the refractive index of the first region 32a is greater than about 1.5 to about 1.9 depending on the concentration of the nanoparticles 36. The refractive index of the second region 32b becomes a value less than about 1.4 to less than about 1.5 depending on the concentration of the nanoparticles 36.

  Since the refractive index of the plurality of convex portions 133 is about 1.5, when a voltage is applied between the first electrode layer 40 and the second electrode layer 50, the convex portion 133 and the first region 32a There is a difference in refractive index between them. For this reason, as shown in FIG. 6C, when the light L is incident from an oblique direction, the incident light L is refracted by the first side surface 133a of the convex portion 133 and then totally reflected by the second side surface 133b. Thereafter, the light L is refracted and emitted from the second substrate 20 by the difference in refractive index between the second region 32 b and the convex portion 33 of the first concavo-convex structure layer 31.

  Accordingly, as shown in FIG. 6C, the incident angle and the emission angle of the light L are different in the vertical cross section. For example, the light L incident from diagonally upward to diagonally downward is emitted from the optical device 101 diagonally upward.

  As described above, when a predetermined voltage is applied between the first electrode layer 40 and the second electrode layer 50, there is a difference in refractive index at the interface between each of the plurality of convex portions 133 and the refractive index variable layer 32. The traveling direction of the light generated and incident on the light control layer 130 is bent. That is, the optical device 101 enters a light distribution state in which incident light is transmitted with its traveling direction bent.

  Further, the degree of aggregation of the nanoparticles 36 can be changed depending on the magnitude of the applied voltage. The refractive index of the refractive index variable layer 32 changes depending on the degree of aggregation of the nanoparticles 36. For this reason, it is also possible to change the light distribution direction by changing the difference in refractive index between the first side surface 133a and the second side surface 133b (interface) of the convex portion 133.

[Effects, etc.]
As described above, the optical device 101 according to the present embodiment has the second concavo-convex structure having the plurality of convex portions 133 arranged between the first electrode layer 40 and the second electrode layer 50 and arranged in a predetermined direction. A layer 131 is provided. The refractive index variable layer 32 is further arranged so as to fill in the space between the plurality of convex portions 133. When a refractive index difference is generated between the second uneven structure layer 131 and the refractive index variable layer 32, the light incident from the first substrate 10 is directed toward the second substrate 20 and a plurality of convex portions 133. And the refractive index variable layer 32 are reflected.

  Thereby, not only a reflection state and a transparent state but a light distribution state can be realized. Specifically, when the optical device 101 is used for a window, the optical device 101 can emit light obliquely upward when transmitting light that is incident obliquely downward, such as sunlight. Thereby, since an indoor ceiling can be illuminated, indoors can be brightened.

  In addition, according to the present embodiment, since the reflection state (that is, the heat shielding state), the transparent state, and the light distribution state can be switched, the optical device 101 can be used for heat shielding and lighting when used for a window. And both.

  For example, the planar view shape of the plurality of convex portions 133 is a stripe shape. The cross-sectional shape of each of the plurality of convex portions 133 is a substantially trapezoidal shape or a substantially triangular shape.

  Thereby, when the cross-sectional shape of the convex part 133 is a substantially trapezoid, the moldability of the convex part 133 improves, for example, the die cutting at the time of shaping | molding by nanoimprint etc. can be performed easily. For this reason, the reliability of the shape of the convex part 133 etc. increases, and a highly reliable light distribution performance etc. are realizable. Moreover, when the cross-sectional shape of the convex part 133 is a substantially triangle, the number of the convex parts 133 which can be arrange | positioned in a surface can be increased. Therefore, the light distribution rate can be increased.

  Further, for example, the two base angles of a substantially trapezoid or a substantially triangle are 65 ° or more and 90 ° or less, respectively.

  Accordingly, the second side surface 133b can be easily made to function as a light total reflection surface, so that the light distribution rate can be increased.

(Other)
Although the optical device according to the present invention has been described based on the above embodiment, the present invention is not limited to the above embodiment.

  For example, the first concavo-convex structure layer 31 may be provided on the first substrate 10 side, that is, on the outdoor side. For example, the first concavo-convex structure layer 31 may have prism-shaped convex portions 33 or beads that perform retroreflection, and may be provided on the first substrate 10 side. At this time, in the reflection state, the refractive index relationship between the refractive index variable layer 32 and the convex portion 33 is different from that of the above-described embodiment. Specifically, the refractive index of the refractive index variable layer 32 is lower than the refractive index of the convex portion 33. More specifically, the refractive index of the refractive index variable layer 32 is lower than the refractive index of the convex portion 33 by 0.3 or more. By appropriately adjusting the resin material constituting the convex portion 33 and the electrophoretic material constituting the refractive index variable layer 32, a desired refractive index relationship can be obtained.

  Further, for example, the refractive index of the first uneven structure layer 31 and the refractive index of the second uneven structure layer 131 may be different.

  Further, for example, the plurality of convex portions 133 may be divided into a plurality of portions in the x-axis direction. For example, the plurality of convex portions 133 may be arranged so as to be scattered in a matrix or the like. That is, you may arrange | position the some convex part 133 so that it may be scattered in dot shape.

  For example, in the above-described embodiment, the refractive index of the nanoparticles 36 may be lower than the refractive index of the insulating liquid 35. A transparent state and a light distribution state can be realized by appropriately adjusting the voltage to be applied according to the refractive index of the nanoparticles 36. For example, the light distribution state may be realized when a voltage is not applied between the first electrode layer 40 and the second electrode layer 50, and the transparent state may be realized when a voltage is applied.

  Further, for example, in the above-described embodiment, the nanoparticles 36 are positively charged. However, the present invention is not limited to this. That is, the nanoparticles 36 may be negatively charged. In this case, a direct voltage is applied between the first electrode layer 40 and the second electrode layer 50 by applying a positive potential to the first electrode layer 40 and applying a negative potential to the second electrode layer 50. Good.

  The plurality of nanoparticles 36 may include a plurality of types of nanoparticles having different optical characteristics. For example, a transparent first nanoparticle charged positively and an opaque (black or the like) second nanoparticle charged negatively may be included. For example, the optical device may have a light shielding function by aggregating and unevenly distributing the second nanoparticles.

  For example, in the above-described embodiment, an example in which an electrophoretic material is used as the refractive index variable material has been described. For example, a liquid crystal material may be used as the refractive index variable material. In this case, the refractive index of the refractive index variable layer changes using the birefringence of the liquid crystal molecules contained in the liquid crystal material. By changing the orientation of the liquid crystal molecules in accordance with the electric field applied to the refractive index variable layer, the refractive index of the refractive index variable layer changes. Thereby, it is possible to control the transparent state, the reflection state, the light distribution state, and the light distribution direction in the light distribution state.

  Moreover, in said embodiment, although sunlight was illustrated as light which injects into an optical device, it is not restricted to this. For example, the light incident on the optical device may be light emitted from a light emitting device such as a lighting device.

  For example, the optical device is not limited to being installed in a building window, and may be installed in a car window, for example. Moreover, an optical device can also be utilized for light distribution control members, such as a translucent cover of a lighting fixture, for example. Alternatively, the optical device can also be used as a blindfold member that utilizes light scattering at the interface of the concavo-convex structure.

  In addition, the embodiment can be realized by arbitrarily combining the components and functions in each embodiment without departing from the scope of the present invention, or a form obtained by subjecting each embodiment to various modifications conceived by those skilled in the art. Forms are also included in the present invention.

DESCRIPTION OF SYMBOLS 1,101 Optical device 10 1st board | substrate 20 2nd board | substrate 31 1st uneven structure layer 32 Refractive index variable layer 33, 133 Convex part 34, 134 Concave part 35 Insulating liquid 36 Nanoparticle 40 1st electrode layer 50 2nd electrode layer 131 2nd uneven structure layer

Claims (9)

A first substrate having translucency;
A second substrate having translucency, disposed opposite to the first substrate;
A translucent first electrode layer and a second electrode layer disposed opposite to each other between the first substrate and the second substrate;
A first concavo-convex structure layer disposed between the first electrode layer and the second electrode layer;
A refractive index variable layer that is arranged so as to fill the irregularities of the first concavo-convex structure layer and whose refractive index changes according to a voltage applied between the first electrode layer and the second electrode layer;
The optical device having a retroreflective structure in which incident light is retroreflected by the unevenness when a refractive index difference is generated between the first uneven structure layer and the refractive index variable layer. The optical device according to claim 1, wherein the refractive index of the refractive index variable layer can be changed to a refractive index at which a refractive index difference from the first uneven structure layer is 0.3 or more. The optical device according to claim 1, wherein a height of the unevenness of the first uneven structure layer is 5 μm or more and 50 μm or less. The optical device according to claim 1, wherein the retroreflective structure is a prism structure or a bead structure. The optical device according to claim 1, wherein a refractive index of the refractive index variable layer can be changed to a refractive index substantially the same as a refractive index of the first uneven structure layer. And a second concavo-convex structure layer having a plurality of convex portions arranged in a predetermined direction, disposed between the first electrode layer and the second electrode layer,
The refractive index variable layer is further arranged so as to fill between the plurality of convex portions,
When the refractive index difference occurs between the second uneven structure layer and the refractive index variable layer, the plurality of protrusions directs light incident from the first substrate toward the second substrate. The optical device according to claim 1, wherein the optical device is reflected at an interface between the refractive index variable layer and the refractive index variable layer. The planar view shape of the plurality of convex portions is a stripe shape,
The optical device according to claim 6, wherein a shape of a cross section of each of the plurality of convex portions is a substantially trapezoidal shape or a substantially triangular shape. The optical device according to claim 7, wherein two base angles of the substantially trapezoidal shape or the substantially triangular shape are 65 ° or more and 90 ° or less, respectively. The refractive index variable layer is
An insulating liquid;
The optical device according to claim 1, comprising a plurality of charged nanoparticles dispersed in the insulating liquid and having a refractive index different from that of the insulating liquid.

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