WO2019167542A1

WO2019167542A1 - Light distribution control device

Info

Publication number: WO2019167542A1
Application number: PCT/JP2019/003523
Authority: WO
Inventors: 旬臣芝田; 太田　益幸
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2018-02-27
Filing date: 2019-01-31
Publication date: 2019-09-06

Abstract

This light distribution control device (1) is provided with: a first electrode layer (40) and a second electrode layer (50), which are arranged to face each other and have light transmitting properties; and a light distribution layer (30) which is arranged between the first electrode layer (40) and the second electrode layer (50). The light distribution layer (30) comprises: a first relief structure layer (31a) which is arranged on the first substrate (10) side and has a plurality of first projected parts (33); a second relief structure layer (31b) which is arranged on the second substrate (20) side and has a plurality of second projected parts (35); and a variable refractive index layer (32) which is arranged so as to fill the spaces between the plurality of first projected parts (33) and the spaces between the plurality of second projected parts (35). The variable refractive index layer (32) comprises: an insulating liquid (37); and a plurality of charged nanoparticles (38) which are dispersed in the insulating liquid (37) and have a refractive index that is different from the refractive index of the insulating liquid (37). The plurality of first projected parts (33) and the plurality of second projected parts (35) respectively extend in the same directions.

Description

Light distribution control device

The present invention relates to a light distribution control device.

Conventionally, a light distribution control device capable of changing the 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.

JP 2015-41006 A

However, the conventional liquid crystal optical element has a problem that when it is used for a window, a person in the room feels dazzled by the bent light.

Therefore, an object of the present invention is to provide a light distribution control device that can brighten indoors and suppress glare felt by people who are indoors when used for windows. .

In order to achieve the above object, a light distribution control device according to one embodiment of the present invention includes a first substrate having translucency, and a second substrate having translucency, which is 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; the first electrode layer and the second electrode layer; And a light distribution layer that distributes incident light, and the light distribution layer is provided on the first substrate side and has a first concavo-convex structure layer having a plurality of first protrusions, A second concavo-convex structure layer provided on the second substrate side and having a plurality of second protrusions, and disposed between the plurality of first protrusions and between the plurality of second protrusions, A refractive index variable layer whose refractive index changes according to a voltage applied between the first electrode layer and the second electrode layer, and the refractive index variable layer Each of the plurality of first protrusions and the plurality of second particles, each having a plurality of charged nanoparticles dispersed in the insulating liquid and having a refractive index different from that of the insulating liquid. Each of the convex portions extends along the same direction.

According to the light distribution control device according to the present invention, when used for a window, the interior can be brightened and the glare felt by a person in the room can be suppressed.

FIG. 1 is a cross-sectional view of a light distribution control device according to an embodiment. FIG. 2 is an enlarged cross-sectional view of the light distribution control device according to the embodiment. FIG. 3A is an enlarged cross-sectional view for explaining a non-application mode (transparent state) of the light distribution control device according to the embodiment. FIG. 3B is an enlarged cross-sectional view for explaining a voltage application mode (light distribution state) of the light distribution control device according to the embodiment. FIG. 4 is a diagram illustrating an example when the light distribution control device according to the embodiment is applied to a window of a building. FIG. 5 is a diagram showing the trajectory of the sun observed at a point of about 35 ° north latitude. FIG. 6 is a diagram illustrating each of the light distribution rate, direct radiation rate, and downward irradiation rate of the light distribution control device according to the first embodiment for each incident angle of light. FIG. 7 is a diagram illustrating each of the light distribution rate, direct radiation rate, and downward irradiation rate of the light distribution control device according to the second embodiment for each incident angle of light.

Hereinafter, the light distribution control device according to the 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 not described in the independent claims are described as arbitrary constituent elements.

Each figure is a schematic diagram and is not necessarily shown 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 the present specification, the “thickness direction” means the thickness direction of the light distribution control device, which is a direction perpendicular to the main surfaces of the first substrate and the second substrate, and “plan view” means , When viewed from a direction perpendicular to the main surface of the first substrate or the second substrate.

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

FIG. 1 is a cross-sectional view of a light distribution control device 1 according to the present embodiment. FIG. 2 is an enlarged cross-sectional view of the light distribution control device 1 according to the present embodiment, and is an enlarged cross-sectional view of a region II surrounded by an alternate long and short dash line in FIG.

The light distribution control device 1 is an optical device that controls light incident on the light distribution control device 1. Specifically, the light distribution control device 1 is a light distribution element that can change the traveling direction of light incident on the light distribution control device 1 (that is, distribute light) and emit the light.

As shown in FIGS. 1 and 2, the light distribution control device 1 is configured to transmit incident light, and includes a first substrate 10, a second substrate 20, a light distribution layer 30, One electrode layer 40 and a second electrode layer 50 are provided.

Note that an adhesion layer for closely adhering the first electrode layer 40 and the first uneven structure layer 31a of the light distribution layer 30 may be provided on the surface of the first electrode layer 40 on the light distribution layer 30 side. . Similarly, even if an adhesion layer is provided on the surface of the second electrode layer 50 on the light distribution layer 30 side so that the second electrode layer 50 and the second uneven structure layer 31b of the light distribution layer 30 are adhered to each other. Good. The adhesion layer is, for example, a translucent adhesive sheet or a resin material generally called a primer.

In the light distribution control device 1, the first electrode layer 40, the light distribution layer 30, and the second electrode layer 50 are disposed in this order along the thickness direction between the paired first substrate 10 and second substrate 20. It is a configuration. 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 light distribution control device 1 can be realized, for example, as a window with a light distribution function by being installed in a building window. The light distribution control device 1 is used by being attached to a transparent base material such as an existing window glass through an adhesive layer, for example. Alternatively, the light distribution control device 1 may be used as a building window itself. In the light distribution control device 1, for example, the first substrate 10 is on the outdoor side, the second substrate 20 is on the indoor side, and the first side surface 33a of the first convex portion 33 shown in FIG. The second side surface 33b is on the upper side (ceiling side).

In the light distribution control device 1, the refractive index of the refractive index variable layer 32 of the light distribution layer 30 changes depending on the voltage applied between the first electrode layer 40 and the second electrode layer 50. Thereby, a difference in refractive index is generated at the interface between the first uneven structure layer 31a and the refractive index variable layer 32, and light is distributed using light refraction and reflection (total reflection) by the interface. Further, a difference in refractive index also occurs at the interface between the second uneven structure layer 31b and the refractive index variable layer 32, and light is partially diffused by utilizing light refraction and reflection (total reflection) by the interface. .

The light distribution control device 1 switches between the transparent state and the light distribution state according to the magnitude of the voltage applied between the first electrode layer 40 and the second electrode layer 50. In the light distribution control device 1, the light distribution direction (traveling direction) of light in the light distribution state changes according to the magnitude of the voltage applied between the first electrode layer 40 and the second electrode layer 50.

Hereinafter, each component of the light distribution control device 1 will be described in detail with reference to FIGS. 1 and 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 material for the glass substrate include soda glass, alkali-free 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 made of the same material, or may be made 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 planar 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 distribution layer]
As shown in FIGS. 1 and 2, the light distribution layer 30 is disposed between the first electrode layer 40 and the second electrode layer 50. The light distribution layer 30 has translucency and transmits incident light. The light distribution layer 30 distributes the incident light. That is, the light distribution layer 30 changes the traveling direction of light when the light passes through the light distribution layer 30.

The light distribution layer 30 includes a first uneven structure layer 31a, a second uneven structure layer 31b, and a refractive index variable layer 32. In the present embodiment, light is reflected at the interface between the first concavo-convex structure layer 31a and the refractive index variable layer 32, whereby the traveling direction of the light transmitted through the light distribution control device 1 is bent.

[First uneven structure layer]
The first concavo-convex structure layer 31a is a finely shaped layer provided to make the surface (interface) of the refractive index variable layer 32 uneven. As shown in FIG. 2, the first uneven structure layer 31 a includes a plurality of first protrusions 33 and a plurality of first recesses 34.

Specifically, the first concavo-convex structure layer 31a is a concavo-convex structure constituted by a plurality of first convex portions 33 having a micro-order size. Between the plurality of first protrusions 33 are a plurality of first recesses 34. That is, one first concave portion 34 is between two adjacent first convex portions 33. In the example shown in FIG. 2, an example is shown in which a plurality of first protrusions 33 are connected to each other at the root (on the first electrode layer 40 side), but the present invention is not limited to this. The several 1st convex part 33 may be isolate | separated separately. In addition, for example, a layer (film) -like base portion serving as a base of the first convex portion 33 may be provided between the plurality of first convex portions 33 and the first electrode layer 40.

The plurality of first protrusions 33 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 first convex portions 33.

In the present embodiment, the plurality of first protrusions 33 are long ridges extending in a direction orthogonal to the arrangement direction. Specifically, the plurality of first protrusions 33 are formed in a stripe shape extending in the x-axis direction. Each of the plurality of first protrusions 33 extends linearly along the x-axis direction. For example, each of the plurality of first protrusions 33 is a quadrangular prism that is disposed sideways with respect to the first electrode layer 40. The plurality of first convex portions 33 may extend while meandering along the x-axis direction. For example, the plurality of first protrusions 33 may be formed in a wavy stripe shape.

2, each of the plurality of first protrusions 33 has a shape that tapers from the root to the tip. Specifically, the cross-sectional shape of each of the plurality of first protrusions 33 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 first convex portion 33 in the yz cross section is a substantially trapezoid that tapers along the thickness direction of the light distribution control device 1, but is not limited thereto. The cross-sectional shape of the first convex portion 33 may be a substantially triangular shape, other polygons, or a polygon including a curve. The shapes of the plurality of first protrusions 33 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. 2, each of the plurality of first convex portions 33 has a first side surface 33a and a second side surface 33b. The first side surface 33a and the second side surface 33b are surfaces that intersect the z-axis direction. Each of the first side surface 33a and the second side surface 33b 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 33 a and the second side surface 33 b, that is, the width of the first convex portion 33 gradually decreases from the first substrate 10 toward the second substrate 20.

For example, when the light distribution control device 1 is arranged so that the z axis coincides with the vertical direction, the first side surface 33a is a side surface on the vertically lower side among the plurality of side surfaces constituting the first convex portion 33. . The first side surface 33a is a refracting surface that refracts incident light.

For example, when the light distribution control device 1 is arranged so that the z axis coincides with the vertical direction, the second side surface 33b is a side surface on the vertically upper side among the plurality of side surfaces constituting the first convex portion 33. . The second side surface 33b is a reflecting surface that reflects incident light. The reflection here is total reflection, and the second side surface 33b functions as a total reflection surface.

In the present embodiment, the first side surface 33a and the second side surface 33b refract and reflect at least part of the light incident on the light distribution layer 30. Thereby, at least a part of the light passing through the light distribution layer 30 is bent up and down.

The inclination angle α _down of the first side surface 33a and the inclination angle α _up of the second side surface 33b 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 first convex portion 33 are 65 ° or more and 90 ° or less, respectively. Alternatively, at least one of the two base angles may be smaller than 65 °.

The width (length in the z-axis direction) of the plurality of first protrusions 33 is, for example, 1 μm to 20 μm, and preferably 10 μm or less, but is not limited thereto. The interval between two adjacent first convex portions 33 is, for example, 0 μm to 100 μm, but is not limited thereto.

As the material of the first concavo-convex structure layer 31a, for example, a light-transmissive resin material such as acrylic resin, epoxy resin, or silicone resin can be used. The first uneven structure layer 31a 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 31a 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.

[Second uneven structure layer]
The second concavo-convex structure layer 31b is a finely shaped layer provided to make the surface (interface) of the refractive index variable layer 32 uneven. As shown in FIG. 2, the second uneven structure layer 31 b includes a plurality of second protrusions 35 and a plurality of second recesses 36.

Specifically, the second concavo-convex structure layer 31b is a concavo-convex structure constituted by a plurality of second convex portions 35 having a micro-order size. Between the plurality of second convex portions 35 are a plurality of second concave portions 36. That is, one second concave portion 36 is between two adjacent second convex portions 35. In the example shown in FIG. 2, an example is shown in which a plurality of second convex portions 35 are connected to each other at the root (second electrode layer 50 side), but the present invention is not limited to this. The plurality of second convex portions 35 may be individually separated. In addition, for example, a layer (film) -like base portion serving as a base of the second convex portion 35 may be provided between the plurality of second convex portions 35 and the second electrode layer 50.

The plurality of second protrusions 35 are a plurality of protrusions arranged side by side in the z-axis direction parallel to the main surface of the second substrate 20 (the surface on which the second electrode layer 50 is provided). That is, in the present embodiment, the z-axis direction is an arrangement direction of the plurality of second convex portions 35.

In the present embodiment, the plurality of second convex portions 35 are long ridges extending in a direction orthogonal to the arrangement direction. Specifically, the plurality of second convex portions 35 are formed in a stripe shape extending in the x-axis direction. Each of the plurality of second convex portions 35 extends linearly along the x-axis direction. For example, each of the plurality of second convex portions 35 is a rectangular column that is disposed sideways with respect to the second electrode layer 50. The plurality of second convex portions 35 may extend while meandering along the x-axis direction. For example, the plurality of second convex portions 35 may be formed in a wavy stripe shape.

Thus, each of the plurality of first protrusions 33 of the first uneven structure layer 31a and each of the plurality of second protrusions 35 of the second uneven structure layer 31b extend in the same direction.

2, each of the plurality of second convex portions 35 has a shape that tapers from the root to the tip. Specifically, the cross-sectional shape of each of the plurality of second convex portions 35 is a tapered shape that tapers along the direction from the second substrate 20 toward the first substrate 10. In the present embodiment, the cross-sectional shape in the yz section of the second convex portion 35 is a substantially trapezoidal shape that tapers along the thickness direction of the light distribution control device 1, but is not limited thereto. The cross-sectional shape of the second convex portion 35 may be a substantially triangular shape, other polygons, or a polygon including a curve. The shapes of the plurality of second convex portions 35 are the same as each other, but may be different.

In the present embodiment, as shown in FIG. 2, each of the plurality of second convex portions 35 has a first side surface 35a and a second side surface 35b. The first side surface 35a and the second side surface 35b are surfaces that intersect the z-axis direction. Each of the first side surface 35a and the second side surface 35b 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 35 a and the second side surface 35 b, that is, the width of the second convex portion 35 gradually decreases from the second substrate 20 toward the first substrate 10.

For example, when the light distribution control device 1 is arranged so that the z-axis coincides with the vertical direction, the first side surface 35a is a side surface on the vertically lower side among the plurality of side surfaces constituting the second convex portion 35. .

For example, when the light distribution control device 1 is arranged so that the z axis coincides with the vertical direction, the second side surface 35b is a side surface on the vertically upper side among the plurality of side surfaces constituting the second convex portion 35. .

In the present embodiment, the first side surface 35a and the second side surface 35b refract or reflect part of the light that has passed through the refractive index variable layer 32. Thereby, a part of the light passing through the light distribution layer 30 is diffused.

The inclination angle β _down of the first side surface 35a and the inclination angle β _up of the second side surface 35b 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 which are the cross-sectional shape of the second convex portion 35 are 65 ° or more and 90 ° or less, respectively. Alternatively, at least one of the two base angles may be smaller than 65 °.

The width (length in the z-axis direction) of the plurality of second convex portions 35 is, for example, 1 μm to 20 μm, and preferably 10 μm or less, but is not limited thereto. Further, the interval between two adjacent second convex portions 35 is, for example, 0 μm to 100 μm, but is not limited thereto.

The material of the second concavo-convex structure layer 31b is the same as the material of the first concavo-convex structure layer 31a. For example, a resin material having optical transparency such as an acrylic resin, an epoxy resin, or a silicone resin can be used. The material of the second uneven structure layer 31b may be different from the material of the first uneven structure layer 31a. At this time, the first uneven structure layer 31a and the second uneven structure layer 31b may have the same or different refractive indexes.

The second uneven structure layer 31b 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 31b 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 for green light.

The second concavo-convex structure layer 31b has, for example, a shape and arrangement obtained by inverting the first concavo-convex structure layer 31a. In the present embodiment, the arrangement interval of the first projections 33 and the arrangement interval of the second projections 35 are equal, and the tip of the first projection 33 and the tip of the second projection 35 face each other. However, it is not limited to this. The distal end portion of the first convex portion 33 and the distal end portion of the second convex portion 35 may be shifted from each other in the z-axis direction. Further, the arrangement interval of the first protrusions 33 and the arrangement interval of the second protrusions 35 may be different.

Further, the first convex portion 33 and the second convex portion 35 may be different in size and shape. Specifically, the inclination angle α _down of the first side surface 33 a of the first convex portion 33 may be different from the inclination angle β _down of the first side surface 35 a of the second convex portion 35. The inclination angle α _up of the second side surface 33 b of the first convex portion 33 may be different from the inclination angle β _up of the second side surface 35 b of the second convex portion 35.

[Refractive index variable layer]
The refractive index variable layer 32 is disposed so as to fill between the plurality of first protrusions 33 (that is, the first recesses 34) and between the plurality of second protrusions 35 (that is, the second recesses 36). Yes. 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. For example, as shown in FIG. 2, since the tip of the first protrusion 33 and the tip of the second protrusion 35 are separated from each other, the refractive index variable layer 32 includes the first recess 34 and the second recess 36. Moreover, it arrange | positions so that the clearance gap between the front-end | tip part of the 1st convex part 33 and the front-end | tip part of the 2nd convex part 35 may be filled up. The tip of the first protrusion 33 and the tip of the second protrusion 35 may be in contact with each other. In this case, the refractive index variable layer 32 is formed by the first recess 34 and the second recess 36. It may be provided separately for each space.

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 an electric field is applied. The electric field changes according to the voltage applied between the first electrode layer 40 and the second electrode layer 50. For example, a DC voltage is applied between the first electrode layer 40 and the second electrode layer 50 by a control unit (not shown).

2, the refractive index variable layer 32 includes an insulating liquid 37 and nanoparticles 38 included in the insulating liquid 37. The refractive index variable layer 32 is a nanoparticle dispersion layer in which countless nanoparticles 38 are dispersed in an insulating liquid 37.

The insulating liquid 37 is a transparent liquid having insulating properties, and is a solvent serving as a dispersion medium in which the nanoparticles 38 are dispersed as a dispersoid. As the insulating liquid 37, for example, a material having a refractive index (solvent refractive index) of about 1.3 to about 1.6 can be used. In this embodiment, an insulating liquid 37 having a refractive index of about 1.4 is used.

The kinematic viscosity of the insulating liquid 37 is preferably about 100 mm ² / s. The insulating liquid 37 has a low dielectric constant (for example, less than the dielectric constant of the first concavo-convex structure layer 31a and the second concavo-convex structure layer 31b) and non-flammability (for example, a high flash point having a flash point of 250 ° C. or higher). ) And low volatility. Specifically, the insulating liquid 37 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 37 is a halogenated hydrocarbon such as a fluorinated hydrocarbon. As the insulating liquid 37, silicone oil or the like can be used.

A plurality of nanoparticles 38 are dispersed in the insulating liquid 37. The nanoparticles 38 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 38 is preferably λ / 4 or less. By setting the particle size of the nanoparticles 38 to λ / 4 or less, light scattering by the nanoparticles 38 can be reduced, and an average refractive index of the nanoparticles 38 and the insulating liquid 37 can be obtained. The particle size of the nanoparticles 38 is preferably as small as possible, preferably 100 nm or less, more preferably several nm to several tens nm.

The nanoparticles 38 are made of, for example, a high refractive index material. Specifically, the refractive index of the nanoparticles 38 is higher than the refractive index of the insulating liquid 37. In the present embodiment, the refractive index of the nanoparticles 38 is higher than the refractive indexes of the first uneven structure layer 31a and the second uneven structure layer 31b.

As the nanoparticles 38, for example, metal oxide fine particles can be used. The nanoparticles 38 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 38. The nanoparticles 38 are not limited to zirconium oxide, and may be composed of titanium oxide (TiO ₂ : refractive index 2.5) or the like.

Further, the nanoparticles 38 are charged particles that are charged. For example, by modifying the surface of the nanoparticles 38, the nanoparticles 38 can be charged positively (plus) or negatively (minus). In the present embodiment, the nanoparticles 38 are positively (plus) charged.

In the refractive index variable layer 32 configured in this way, charged nanoparticles 38 are dispersed throughout the insulating liquid 37. In this embodiment, as an example, zirconia particles having a refractive index of 2.1 as nanoparticles 38 and dispersed in an insulating liquid 37 having a solvent refractive index of about 1.4 are used as the refractive index variable layer 32. It is said.

The refractive index (average refractive index) of the entire refractive index variable layer 32 is such that the first concavo-convex structure layer 31 a and the second concavo-convex structure layer 31 b in a state where the nanoparticles 38 are uniformly dispersed in the insulating liquid 37. The refractive index is set to be substantially the same, and in the present embodiment, it is about 1.5. The overall refractive index of the refractive index variable layer 32 can be changed by adjusting the concentration (amount) of the nanoparticles 38 dispersed in the insulating liquid 37. Although details will be described later, the amount of the nanoparticles 38 is, for example, such that it is buried in the first recess 34 of the first uneven structure layer 31a. In this case, the concentration of the nanoparticles 38 with respect to the insulating liquid 37 is about 10% to about 30%.

Since the nanoparticles 38 dispersed in the insulating liquid 37 are charged, when an electric field is applied to the refractive index variable layer 32, the nanoparticles 38 migrate in the insulating liquid 37 in accordance with the electric field distribution, and the insulating liquid 37 37 is unevenly distributed. As a result, the particle distribution of the nanoparticles 38 in the refractive index variable layer 32 can be changed to give the concentration distribution of the nanoparticles 38 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.

The refractive index variable layer 32 includes, for example, the first substrate 10 on which the first electrode layer 40 and the first uneven structure layer 31a are formed, and the second substrate on which the second electrode layer 50 and the second uneven structure layer 31b are formed. In a state where the outer periphery of each of the

end portions

20 and 20 is sealed with a sealing resin, the refractive index variable material is injected by a vacuum injection method. Alternatively, in the refractive index variable layer 32, after the refractive index variable material is dropped onto the first electrode layer 40 and the first uneven structure layer 31a of the first substrate 10, the second electrode layer 50 and the second uneven structure layer 31b are formed. You may form by bonding the formed 2nd board | substrate 20 together. In the present embodiment, the refractive index variable material is an insulating liquid 37 in which nanoparticles 38 are dispersed. An insulating liquid 37 in which nanoparticles 38 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, and are configured to be able to apply an electric field to the light distribution layer 30. . 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 arranged so as to sandwich the light distribution layer 30.

The first electrode layer 40 and the second electrode layer 50 are translucent 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 first uneven structure layer 31a. Specifically, the first electrode layer 40 is formed on the surface of the first substrate 10 on the light distribution layer 30 side.

On the other hand, the second electrode layer 50 is disposed between the second concavo-convex structure layer 31b and the second substrate 20. Specifically, the second electrode layer 50 is formed on the surface of the second substrate 20 on the light distribution 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.

The first electrode layer 40 and the second electrode layer 50 are each formed by forming a conductive film such as ITO by vapor deposition, sputtering, or the like, for example.

[Operation and optical state of light distribution control device]
Next, the operation and optical state of the light distribution control device 1 will be described.

<Transparent state (non-application mode)>
FIG. 3A is an enlarged cross-sectional view for explaining a non-application mode (transparent state) of the light distribution control device 1 according to the present embodiment. In FIG. 3A, the path of the light L incident obliquely on the light distribution control 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 no electric field is applied to the refractive index variable layer 32, the nanoparticles 38 are dispersed throughout the insulating liquid 37.

In the present embodiment, the refractive index of the refractive index variable layer 32 in a state where the nanoparticles 38 are dispersed throughout the insulating liquid 37 is about 1.5 as described above. Moreover, the refractive index of the 1st convex part 33 of the 1st uneven structure layer 31a and the refractive index of the 2nd convex part 35 of the 2nd uneven structure layer 31b are about 1.5. That is, the plurality of first protrusions 33, the plurality of second protrusions 35, and the refractive index variable layer 32 have the same refractive index. Therefore, the refractive index is uniform throughout the light distribution layer 30.

For this reason, as shown in FIG. 3A, when light L is incident from an oblique direction, there is no difference in refractive index at the interface between the refractive index variable layer 32 and the first concavo-convex structure layer 31a, so that the light travels straight. To do. Similarly, since there is no refractive index difference at the interface between the refractive index variable layer 32 and the second concavo-convex structure layer 31b, light travels straight. That is, the incident angle θin and the outgoing angle θout of the light L are substantially the same. In this way, the light distribution control 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. In FIG. 3A, the traveling direction of the light L in the light distribution layer 30 is illustrated in detail. The same applies to FIG. 3B described later.

<Light distribution state (voltage application mode)>
FIG. 3B is an enlarged cross-sectional view for explaining a voltage application mode (light distribution state) of the light distribution control device 1 according to the present embodiment. In FIG. 3B, the path of the light L incident obliquely on the light distribution control 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. As a result, a predetermined electric field is applied to the refractive index variable layer 32, and therefore, in the refractive index variable layer 32, the charged nanoparticles 38 migrate in the insulating liquid 37 according to the electric field distribution. That is, the nanoparticles 38 are electrophoresed in the insulating liquid 37.

In the example shown in FIG. 3B, the second electrode layer 50 is at a higher potential than the first electrode layer 40. For this reason, the positively charged nanoparticles 38 migrate toward the first electrode layer 40, and enter and accumulate in the first recesses 34 of the first concavo-convex structure layer 31a.

As described above, the nanoparticles 38 are unevenly distributed on the first uneven structure layer 31a side in the refractive index variable layer 32, whereby the particle distribution of the nanoparticles 38 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 nanoparticles 38 is formed in the refractive index variable layer 32.

For example, in the first region 32a on the first uneven structure layer 31a side, the concentration of the nanoparticles 38 is high, and in the second region 32b on the second uneven structure layer 31b side, the concentration of the nanoparticles 38 is low. Accordingly, a difference in refractive index occurs between the first region 32a and the second region 32b.

In this embodiment, the refractive index of the nanoparticles 38 is higher than the refractive index of the insulating liquid 37. Therefore, the refractive index of the first region 32a where the concentration of the nanoparticles 38 is high is higher than the refractive index of the second region 32b where the concentration of the nanoparticles 38 is low, that is, the proportion of the insulating liquid 37 is large. For example, the refractive index of the first region 32a is greater than about 1.5 to about 1.8 depending on the concentration of the nanoparticles 38. The refractive index of the second region 32b is a value less than about 1.4 to less than about 1.5 depending on the concentration of the nanoparticles 38.

Since the refractive index of the plurality of first protrusions 33 is about 1.5, when a voltage is applied between the first electrode layer 40 and the second electrode layer 50, the first protrusions 33 and the first protrusions 33 A refractive index difference occurs between the region 32a and the region 32a. Therefore, as shown in FIG. 3B, when the light L is incident from an oblique direction, the incident light L is refracted by the first side surface 33a of the first convex portion 33 and then totally reflected by the second side surface 33b. .

Furthermore, since the refractive index of the plurality of second convex portions 35 is about 1.5, a slight difference in refractive index is also generated between the second convex portion 35 and the second region 32b. At this time, the refractive index difference between the second convex portion 35 and the second region 32b is smaller than the refractive index difference between the first convex portion 33 and the first region 32a. A part of the light totally reflected by the second side surface 33 b of the first convex portion 33 is refracted or reflected by the first side surface 35 a or the second side surface 35 b of the second convex portion 35. For this reason, the light totally reflected by the second side surface 33b is partially scattered.

Thereby, the light L incident obliquely downward is bent in the traveling direction by the light distribution control device 1 and irradiated to the indoor ceiling surface or the like. At this time, a part of the light is scattered and emitted to a wide range.

Thus, when a predetermined potential difference occurs between the first electrode layer 40 and the second electrode layer 50, each of the plurality of first protrusions 33 and each of the plurality of second protrusions 35 and the refractive index. A difference in refractive index occurs at the interface with the variable layer 32, and the traveling direction of light incident on the light distribution layer 30 is bent. That is, the light distribution control device 1 enters a light distribution state in which incident light is transmitted with its traveling direction bent.

Further, the degree of aggregation of the nanoparticles 38 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 38. 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 33 a and the second side surface 33 b (interface) of the first convex portion 33.

[Optical characteristics in the light distribution state]
Next, the optical characteristics of the light distribution control device 1 configured as described above will be described. First, an application example of the light distribution control device 1 will be described.

FIG. 4 is a diagram showing an example when applied to the window of the building 90 of the light distribution control device 1 according to the present embodiment. As shown in FIG. 4, the light distribution control device 1 is used by being attached to a window glass 93, for example, and is disposed so as to incorporate light into a building 90.

FIG. 4 shows a building having a height from the floor 92 to the ceiling 91 of 2.7 m and a depth of 9 m as an example of the building 90. The window glass 93 is provided in a range of height 2.4 m from 30 cm above the floor to the ceiling 91.

The light distribution control device 1 is provided in the upper half area of the window glass 93. At this time, a light distribution control device having characteristics different from those of the light distribution control device 1 may be provided in the lower half region of the window glass 93. Alternatively, a device that does not have a light distribution function may be provided in the lower half region. The light distribution control device 1 may be provided on the entire window glass 93.

As described above, the light distribution control device 1 causes the light to travel toward the ceiling 91 by totally reflecting outside light such as sunlight, and illuminates the indoor ceiling 91 brightly. At this time, the light distribution control device 1 is required to suppress the glare felt by the person 94 who is indoors.

In the example shown in FIG. 4, the person 94 is present at a position 1.6 m away from the window glass 93, and shows a case where the person 94 is standing and a case where he is sitting. Here, the height of the line of sight when standing is 1.6 m from the floor 92, and the height of the line of sight when sitting is 1.2 m from the floor 92. In FIG. 4, the standing person 94 and the sitting person 94 are illustrated in a shifted manner, but in the following description, the case where both are present at a position 1.6 m away from the window glass 93 is shown. Assumed.

FIG. 4 schematically shows the light distribution area 80 and the direct-light area 81. Each of the light distribution region 80 and the direct-light region 81 is expressed in the range of the light emission angle θout when a predetermined part of the light distribution control device 1 is used as a reference. The emission angle θout is expressed as an angle with respect to the horizontal plane, and is expressed as positive on the upper side and negative on the lower side. In the example illustrated in FIG. 4, the predetermined part is the lower end of the light distribution control device 1.

The light distribution region 80 is a region through which light distributed by the light distribution control device 1 passes. For example, the light distribution region 80 is a range in which the light emission angle θout from the lower end of the light distribution control device 1 is 3.6 ° or more and 80 ° or less.

The lower limit value (here, 3.6 °) of the emission angle θout of the light distribution region 80 is defined as a range in which the light distributed by the light distribution control device 1 does not enter the line of sight of the person 94 standing. A value corresponding to the boundary. Specifically, the lower limit value is the difference in height between the lower end of the light distribution control device 1 and the line of sight of the person 94 (here, 0.1 m (= 1.6 m−1.5 m)), It is calculated based on the distance (here 1.6 m) from the light distribution control device 1 to the person 94. Specifically, the lower limit value is calculated by tan ⁻¹ (0.1 / 1.6).

Note that the lower limit value of the emission angle θout is not limited to this, and may be determined so that light can reach the deepest part of the building 90. Specifically, the lower limit value is a difference from the lower end of the light distribution control device 1 to the ceiling 91 (here, 1.2 m) and a distance from the light distribution control device 1 to the innermost part of the building 90 (here, 9m). Specifically, the lower limit value is calculated by tan ⁻¹ (1.2 / 9) and may be 7.6 °.

The direct-light region 81 is a region through which light that can enter the eyes of the person 94 through the light distribution control device 1 passes. Specifically, the direct-light region 81 is a region through which light that directly enters the eyes of the person 94 from the light distribution control device 1 passes. For example, the direct-light region 81 is a range in which the light emission angle θout from the lower end of the light distribution control device 1 is −43 ° to 3.6 °.

The upper limit value (here, 3.6 °) of the emission angle θout of the direct-light region 81 is the boundary between the range where the light distributed by the light distribution control device 1 does not enter the line of sight of the standing person 94 and the range where it enters. Is a value corresponding to. That is, the upper limit value of the direct-light region 81 corresponds to the lower limit value of the light distribution region 80.

The lower limit value (here, −43 °) of the emission angle θout of the direct-light region 81 corresponds to the boundary between the range in which the light transmitted through the light distribution control device 1 does not enter the line of sight of the person 94 sitting. Value. Specifically, the lower limit value is a difference in height between the upper end of the light distribution control device 1 and the line of sight of the sitting person 94 (here, 1.5 m (= 2.7 m-1.2 m)), It is calculated based on the distance (here, 1.6 m) from the light distribution control device 1 to the person 94 sitting. Specifically, the lower limit value is calculated by tan ⁻¹ (1.5 / 1.6).

4 is illustrated with the lower end of the light distribution control device 1 as a reference, the solid line indicating the lower limit value is the upper end of the light distribution control device 1 and the line of sight of the person 94 sitting. It is represented by a line parallel to the broken line connecting

As described above, in the light distribution state, the light distribution control device 1 is not only required to introduce a large amount of light toward the ceiling 91 but also to suppress the glare of the person 94 indoors. Is done.

Specifically, when the light distribution control device 1 is used for a window, it is desirable that the average value of the light distribution rate is 30% or more in order to brighten the interior. The light distribution rate indicates the ratio of light distributed to the light transmitted through the light distribution control device 1 when the light distribution control device 1 is in the light distribution state. Specifically, the light distribution rate is represented by the intensity of light distributed relative to the intensity of incident light.

The light distributed is light distributed toward the ceiling 91 as shown in FIG. 4, for example, light emitted from the light distribution control device 1 within a range of 4 ° to 80 °. is there. That is, the light to be distributed is light that passes through the light distribution control device 1 and passes through the light distribution region 80.

At this time, the light distribution control device 1 does not have to have an average value of the light distribution rate of all incident angles of light of 30% or more, and the average value of the light distribution rate within the predetermined range of the incident angle θin is 30. % Or more.

The range of the incident angle θin depends on the latitude of the place where the light distribution control device 1 is installed, the installation direction of the light distribution control device 1, the surrounding environment, and the like. For example, a case is assumed where the light distribution control device 1 is installed in the south direction in Osaka at about 35 ° north latitude. At this time, the sun moves to draw a locus shown in FIG. 5 according to the season.

FIG. 5 is a diagram showing the movement trajectory of the sun observed at a point of about 35 ° north latitude. The horizontal axis indicates the azimuth angle of the sun with 0 ° as the south, the negative side on the east side, and the positive side on the west side. The vertical axis represents the solar altitude. Since the light distribution control device 1 is provided vertically, the solar altitude corresponds to the incident angle θin of light with respect to the light distribution control device 1.

When light is taken indoors by distributing incident light, for example, it is desired that light be taken in efficiently during the daytime of spring, autumn, and winter except summer. That is, it is desirable that the light distribution rate is 30% or more as the average value in the range where the incident angle θin, which is the range through which the sun during the spring, autumn and winter days can pass, is 20 ° or more and 60 ° or less.

Also, in order to suppress the glare that is felt by people who are indoors, it is desirable that the average value of the direct radiation rate is 10% or less. The direct radiation rate is a ratio of light emitted to the direct radiation region 81 with respect to light incident on the light distribution control device 1 in the light distribution state. The direct radiation rate is represented by the intensity of light emitted to the direct radiation area 81 with respect to the intensity of incident light. For example, the light emitted to the direct irradiation region 81 is light emitted from the light distribution control device 1 within a range of −41 ° to 3.6 °.

In the light distribution control device 1, the average value of the direct radiation rate with respect to the light of all incident angles may not be 10% or less, and the average value of the direct radiation rate within the predetermined range of the incident angle θin is 10% or less. Also good. The range of the incident angle θin at this time is, for example, a range of 0 ° to 60 °. When the solar altitude is low, the amount of light entering the human eye can increase because more light travels indoors. On the other hand, when the solar altitude is high, the amount of light entering the human eye decreases.

Also, in order to suppress the temperature rise indoors, particularly near the window, it is desirable that the average value of the lower irradiation rate is 10% or less. The downward irradiation rate is a ratio of light emitted downward as it is with respect to light incident on the light distribution control device 1 in the light distribution state. That is, the downward irradiation rate corresponds to the proportion of light that travels straight without being distributed by the light distribution control device 1 in the light distribution state. The downward irradiation rate is represented by the intensity of light emitted downward relative to the intensity of incident light.

In the light distribution control device 1, the average value of the lower irradiation rate for light of all incident angles may not be 10% or less, and the average value of the lower irradiation rate within the predetermined range of the incident angle θin is 10% or less. There may be. The range of the incident angle θin at this time is, for example, a range of 60 ° to 80 °.

As described above, in the present embodiment, the condition is that the average value of the light distribution rate is 30% or more, the average value of the direct radiation rate is 10% or less, and the average value of the lower irradiation rate is 10% or less. It is desirable to satisfy. Note that this condition is merely an example, and any one of the light distribution rate, direct radiation rate, and downward irradiation rate may not satisfy this condition.

Hereinafter, a specific example of the light distribution control device 1 that satisfies the above conditions will be described as an example to explain that the above conditions are satisfied.

In Examples 1 and 2 described below, the inclination angle α _down of the first side surface 33 a of the first convex portion 33, the inclination angle α _up of the second side surface 33 b, and the inclination angle of the first side surface 35 a of the second convex portion 35, respectively. The combinations of β _down and the inclination angle β _up of the second side surface 35b are different. Specifically, it is as shown in Table 1 below.

In Example 1, the thickness of the light distribution layer 30 is 1 mm, the height of each of the first convex portion 33 and the second convex portion 35 is 7.5 μm, and each of the first convex portion 33 and the second convex portion 35 is. Of the first convex portion 33 and the second convex portion 35 is triangular, and the gap between two adjacent convex portions is 0 μm (that is, the two adjacent convex portions are in contact at the root) Is assumed). Further, it is assumed that the refractive index of the refractive index variable layer 32 is changed in the range of 1.5 to 1.8 in the first region 32a and is fixed at 1.42 in the second region 32b.

In Example 2, the thickness of the light distribution layer 30 is 1 mm, the height of each of the first convex portion 33 and the second convex portion 35 is 30 μm, and the top side of each of the first convex portion 33 and the second convex portion 35 is 2 μm (that is, the cross-sectional shape of the first convex portion 33 and the second convex portion 35 is trapezoidal), the gap between the two adjacent convex portions is 2 μm (that is, the two adjacent convex portions are separated at the root) Is assumed). Further, it is assumed that the refractive index of the refractive index variable layer 32 is changed in the range of 1.5 to 1.8 in the first region 32a and fixed at 1.4 in the second region 32b.

FIG. 6 is a diagram illustrating each of the light distribution rate, direct radiation rate, and downward irradiation rate of the light distribution control device 1 according to the first embodiment for each incident angle of light. In FIG. 6, the horizontal axis represents the incident angle θin of light, and the vertical axis represents each of the light distribution rate, direct radiation rate, and downward irradiation rate.

As shown in Table 1, the light distribution control device 1 according to the first embodiment includes the combination of the inclination angles of the first side surface 33a and the second side surface 33b of the first convex portion 33 and the first of the second convex portion 35. The combination of the inclination angles of the side surface 35a and the second side surface 35b is the same. Specifically, in Example 1, the first convex portion 33 and the second convex portion 35 have the same shape and the same size.

As shown in FIG. 6, in Example 1, the light distribution rate is 57.1% in the average value and 50.6% (θin) in the range of the incident angle θin of 20 ° to 60 °. = 30 °). Thus, the light distribution rate is 50% or more even at the minimum value. The light distribution rate is 50% or more in the range of 0 ° to 80 ° as well as the incident angle θin of 20 ° to 60 °. That is, the light distribution control device 1 according to the first embodiment has a sufficiently high light distribution rate.

Also, the direct radiation rate has an average value of 2.5% and a maximum value of 4.9% when the incident angle θin is in the range of 0 ° to 80 °. The direct radiation rate is 5% or less even at the maximum value. The direct radiation rate is 5% or less not only in the range of the incident angle θin of 0 ° to 60 ° but also in the range of 0 ° to 80 °. Therefore, the light distribution control device 1 according to the first embodiment has a sufficiently low direct radiation rate.

The lower irradiation rate has an average value of 1.9% and a maximum value of 3.3% when the incident angle θin is in the range of 60 ° to 80 °. In the case where the incident angle θin is low, a portion where the lower irradiation rate is high is included, but in the range where the solar altitude is high such as in summer (specifically, the incident angle θin is in the range of 60 ° to 80 °). The lower irradiation rate is sufficiently low.

As described above, in Example 1, the minimum value of the light distribution rate is 50% or more, the maximum value of the direct radiation rate is 5% or less, and the downward irradiation rate within the range of the incident angle θin of 60 ° to 80 ° is 4%. As shown below, it can be seen that the light distribution control device 1 having extremely excellent optical characteristics can be realized.

FIG. 7 is a diagram illustrating each of the light distribution rate, direct radiation rate, and downward irradiation rate of the light distribution control device 1 according to the second embodiment for each incident angle of light. In FIG. 7, the horizontal axis represents the incident angle θin of light, and the vertical axis represents each of the light distribution rate, direct radiation rate, and downward irradiation rate.

In the light distribution control device 1 according to the second embodiment, as shown in Table 1, the inclination angle α _down of the first side surface 33a of the first convex portion 33 and the inclination angle α _up of the second side surface 33b are the same. . That is, the cross-sectional shape of the first convex portion 33 is an isosceles trapezoid or an isosceles triangle. About the 2nd convex part 35, inclination-angle (beta) _down of the 1st side 35a differs from inclination-angle (beta) _up of the 2nd side 35b.

As shown in FIG. 7, in Example 2, the light distribution rate is 48.5% in the average value and 34.8% (θin) in the range where the incident angle θin is 20 ° to 60 °. = 40 °). Although the light distribution rate is somewhat low in the range of 20 ° to 50 °, a sufficiently high light distribution rate is obtained in the range of 50 ° to 60 °.

The direct radiation rate has an average value of 3.4% and a maximum value of 6.3% when the incident angle θin is in the range of 0 ° to 60 °. Therefore, the light distribution control device 1 according to Example 2 has a sufficiently low direct radiation rate.

The lower irradiation rate has an average value of 4.7% and a maximum value of 6.6% when the incident angle θin is in the range of 60 ° to 80 °. In the case where the incident angle θin is low, a portion where the lower irradiation rate is high is included, but in the range where the solar altitude is high such as in summer (specifically, the incident angle θin is in the range of 60 ° to 80 °). The lower irradiation rate is sufficiently low.

As described above, in Example 2, the light distribution control satisfying the condition that the average value of the light distribution rate is 30% or more, the average value of the direct irradiation rate is 10% or less, and the average value of the lower irradiation rate is 10% or less. It can be seen that the device 1 is realized.

[Effects, etc.]
As described above, the light distribution control device 1 according to the present embodiment includes the first substrate 10 having translucency, and the second substrate 20 having translucency disposed so as to face the first substrate 10. And the first electrode layer 40 and the second electrode layer 50 having translucency, which are disposed opposite to each other between the first substrate 10 and the second substrate 20, and the first electrode layer 40 and the second electrode. The light distribution layer 30 is disposed between the layer 50 and distributes incident light. The light distribution layer 30 is provided on the first substrate 10 side, and includes a first uneven structure layer 31a having a plurality of first protrusions 33, and a second substrate 20 side, and has a plurality of second protrusions 35. A voltage applied between the first electrode layer 40 and the second electrode layer 50, arranged so as to fill the space between the second uneven structure layer 31 b and the plurality of first protrusions 33 and between the plurality of second protrusions 35. And a refractive index variable layer 32 whose refractive index changes according to the above. The refractive index variable layer 32 includes an insulating liquid 37 and a plurality of charged nanoparticles 38 having a refractive index different from that of the insulating liquid 37 and dispersed in the insulating liquid 37, and a plurality of first protrusions 33. And each of the plurality of second convex portions 35 extend along the same direction.

Thereby, since light can be reflected by producing a difference in refractive index at the interface between the first convex portion 33 and the refractive index variable layer 32, light incident obliquely such as sunlight can be efficiently put indoors. Can be introduced. At this time, since the second convex portion 35 is provided on the second substrate 20 side, a difference in refractive index also occurs at the interface between the second convex portion 35 and the refractive index variable layer 32. Since a part of the light reflected by the first convex part 33 can be refracted or reflected by the interface between the second convex part 35 and the refractive index variable layer 32, a part of the light can be scattered.

For example, when the second convex portion 35 is not provided, a part of the light that has been transmitted through the light distribution control device 1 without being distributed is directly reflected on the first side surface 35a and the second side of the second convex portion 35. The light is emitted toward the indoor ceiling by reflection or refraction by the side surface 35b. Thereby, a light distribution rate can be raised compared with the case where the 2nd convex part 35 is not provided.

Further, when the second convex portion 35 is not provided, a part of the light that has passed through the light distribution control device 1 without being distributed is directly reflected on the first side surface 35a and the second side of the second convex portion 35. The light is returned to the light incident side without being emitted indoors by reflection or refraction by the two side surfaces 35b. Thereby, compared with the case where the 2nd convex part 35 is not provided, a direct radiation rate and a downward irradiation rate can be made low.

As described above, the light distribution control device 1 according to the present embodiment can brighten an indoor space when used for a window, and can suppress glare felt by a person in the indoor space.

In the present embodiment, since an electrophoretic material is used, in the light distribution state, the influence of the refractive index difference can be exerted on both P-polarized light and S-polarized light. Thereby, a light distribution rate can be raised and a direct radiation rate and a downward irradiation rate can be made low.

Also, for example, the plurality of first protrusions 33 and the plurality of second protrusions 35 have the same shape and the same size.

Thereby, as also shown in Example 1, the light distribution rate can be increased, and the direct radiation rate and the downward irradiation rate can be lowered.

Further, for example, the shape of the cross section of each of the plurality of first protrusions 33 perpendicular to the same direction is a substantially trapezoid or a substantially triangle.

Thereby, when the cross-sectional shape of the first convex portion 33 is a substantially trapezoidal shape, the moldability of the first convex portion 33 is enhanced, for example, the mold can be easily removed during molding by nanoimprint. For this reason, the reliability of the shape of the 1st convex part 33, etc. increase, and a reliable light distribution performance etc. are realizable. Moreover, when the cross-sectional shape of the 1st convex part 33 is a substantially triangle, the number of the 1st convex parts 33 which can be arrange | positioned in a surface can be increased. Accordingly, the light distribution rate can be increased, and the direct radiation rate and the downward irradiation rate can be reduced.

Further, for example, the two base angles of the substantially trapezoidal shape or the substantially triangular shape which are the cross-sectional shape of the convex portion are 65 ° or more and 90 ° or less, respectively.

This facilitates the functioning of the second side surface 33b as a light total reflection surface, thereby increasing the light distribution rate.

Further, for example, when the first electrode layer 40 and the second electrode layer 50 are equipotential, the plurality of first protrusions 33, the plurality of second protrusions 35, and the refractive index variable layer 32 have a refractive index. Are equivalent.

Thereby, when the 1st electrode layer 40 and the 2nd electrode layer 50 are equipotential, the interface of the 1st convex part 33 and the refractive index variable layer 32, and the 2nd convex part 35 and the refractive index variable layer 32 are obtained. Since the difference in refractive index at the interface with the light becomes almost zero, the light incident on the light distribution layer 30 can be allowed to proceed as it is. Therefore, the light distribution control device 1 can be made transparent. For example, since the light distribution control device 1 can be made transparent when no voltage is applied between the first electrode layer 40 and the second electrode layer 50, the electric power required to maintain the transparent state is substantially eliminated. be able to.

Further, for example, when a predetermined potential difference is generated between the first electrode layer 40 and the second electrode layer 50, the interfaces between each of the plurality of first protrusions 33 and the refractive index variable layer 32, and the plurality of first A difference in refractive index occurs at the interface between each of the two convex portions 35 and the refractive index variable layer 32, and the traveling direction of light incident on the light distribution layer 30 is bent.

Thereby, since the refractive index difference can be changed according to the voltage applied between the first electrode layer 40 and the second electrode layer 50, the traveling direction of the distributed light is changed in the light distribution state. Can do.

(Other)
The light distribution control device according to the present invention has been described based on the above embodiment, but the present invention is not limited to the above embodiment.

For example, at least one of the plurality of first protrusions 33 and the plurality of second protrusions 35 may be divided into a plurality in the x-axis direction. For example, the plurality of first protrusions 33 and the plurality of second protrusions 35 may be arranged so as to be scattered in a matrix or the like. That is, at least one of the plurality of first protrusions 33 and the plurality of second protrusions 35 may be arranged so as to be dotted.

Also, for example, in the above embodiment, the refractive index of the nanoparticles 38 may be lower than the refractive index of the insulating liquid 37. 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 38 and the like.

Also, for example, in the above embodiment, the nanoparticles 38 are positively charged, but the present invention is not limited to this. That is, the nanoparticles 38 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.

Further, the plurality of nanoparticles 38 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 light distribution control device may be provided with 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, the transparent state, the light distribution state, and the light distribution direction in the light distribution state can be controlled.

In the above embodiment, sunlight is exemplified as light incident on the light distribution control device. However, the present invention is not limited to this. For example, the light incident on the light distribution control device may be light emitted from a light emitting device such as a lighting device.

Also, for example, the light distribution control device is not limited to being installed in a building window, and may be installed in a car window, for example. The light distribution control device can also be used for a light distribution control member such as a light-transmitting cover of a lighting fixture. Alternatively, the light distribution control 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 Light distribution control device 10 1st board | substrate 20 2nd board | substrate 30 Light distribution layer 31a 1st uneven structure layer 31b 2nd uneven structure layer 32 Refractive index variable layer 33 1st

convex part

33a, 35a

1st side surface

33b, 35b 2nd Side surface 35 Second convex portion 37 Insulating liquid 38 Nanoparticle 40 First electrode layer 50 Second electrode layer

Claims

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 light distribution layer disposed between the first electrode layer and the second electrode layer for distributing incident light;
The light distribution layer is
A first uneven structure layer provided on the first substrate side and having a plurality of first protrusions;
A second uneven structure layer provided on the second substrate side and having a plurality of second protrusions;
A refraction that is arranged so as to fill between the plurality of first protrusions and between the plurality of second protrusions, and whose refractive index changes according to the voltage applied between the first electrode layer and the second electrode layer. A variable rate layer,
The refractive index variable layer is
An insulating liquid;
A plurality of charged nanoparticles dispersed in the insulating liquid having a refractive index different from that of the insulating liquid;
Each of the plurality of first protrusions and each of the plurality of second protrusions extend along the same direction.
The light distribution control device according to claim 1, wherein the plurality of first protrusions and the plurality of second protrusions have the same shape and the same size.
3. The light distribution control device according to claim 1, wherein a shape of a cross section of each of the plurality of first protrusions orthogonal to the same direction is a substantially trapezoid or a substantially triangle.
The light distribution control device according to claim 3, wherein two base angles of the substantially trapezoidal shape or the substantially triangular shape are 65 ° or more and 90 ° or less, respectively.
When the first electrode layer and the second electrode layer are equipotential, the plurality of first protrusions, the plurality of second protrusions, and the refractive index variable layer have the same refractive index. The light distribution control device according to any one of claims 1 to 4.
When a predetermined potential difference occurs between the first electrode layer and the second electrode layer, an interface between each of the plurality of first protrusions and the refractive index variable layer, and the plurality of second protrusions The light distribution control according to any one of claims 1 to 5, wherein a refractive index difference is generated at an interface between each and the refractive index variable layer, and a traveling direction of light incident on the light distribution layer is bent. device.