JP2019144417A - Optical device - Google Patents

Abstract

To provide an optical device which offers superior optical performance.SOLUTION: An optical device comprises: a light-transmissive first substrate 10; a light-transmissive second substrate 20 disposed facing the first substrate 10; a first electrode 30 disposed on the second substrate 20 side of the first substrate 10; an uneven structure 50 disposed on the second substrate 20 side of the first substrate 10; a second electrode 40 disposed on the first substrate 10 side of the second substrate 20; and a variable refractive index layer 60 disposed between the uneven structure 50 and the second electrode 40, the variable refractive index layer having a refractive index that varies with a voltage applied between the first electrode 30 and the second electrode 40. The variable refractive index layer 60 contains an insulative liquid 61 and nanoparticles 62 dispersed in the insulative liquid 61, the nanoparticles 62 having a refractive index greater than that of the insulative liquid 61. At least either of the first electrode 30 and the second electrode 40 is made of a metal having less ionization tendency than hydrogen.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an optical device.

  Conventionally, a light distribution device capable of distributing incident light has been proposed as an optical device. Such an optical device is used for a window of a building or a car. For example, by installing an optical device on a window of a building, the traveling direction of outside light such as sunlight entering from outside the room can be changed and the outside light can be introduced toward the ceiling in the room.

  As this type of light distribution device, one using liquid crystal is known. For example, Patent Document 1 discloses a liquid crystal optical element that includes a pair of transparent substrates, a pair of transparent electrode layers disposed inside the pair of transparent substrates, and a liquid crystal layer disposed between the pair of transparent electrodes. It is disclosed.

JP2015-41006A

  An object of the present invention is to provide an optical device having excellent optical performance.

  In order to achieve the above object, an aspect of the optical device according to the present invention includes a first substrate having light transmittance, a second substrate having light transmittance disposed to face the first substrate, A first electrode disposed on the second substrate side of the first substrate; a concavo-convex structure disposed on the second substrate side of the first substrate; and a first substrate side of the second substrate. The second electrode, a refractive index variable layer that is disposed between the concavo-convex structure and the second electrode, and whose refractive index changes according to a voltage applied between the first electrode and the second electrode. The refractive index variable layer includes an insulating liquid and nanoparticles dispersed in the insulating liquid, and the refractive index of the nanoparticles is higher than the refractive index of the insulating liquid, At least one of the first electrode and the second electrode is made of a metal having a smaller ionization tendency than hydrogen. It is configured Te.

  According to the present invention, an optical device having excellent optical performance can be realized.

It is sectional drawing which shows typically the optical device which concerns on embodiment. It is an expanded sectional view of the optical device which concerns on embodiment. It is a figure for demonstrating the 1st optical effect | action of the optical device which concerns on embodiment. It is a figure for demonstrating the 2nd optical effect | action of the optical device which concerns on embodiment. It is a figure for demonstrating the 3rd optical effect | action of the optical device which concerns on embodiment. It is an expanded sectional view showing an optical device concerning a modification typically. It is sectional drawing which shows typically the structure of the optical device (before voltage application) used in experiment. It is sectional drawing which shows typically the structure of the optical device (at the time of voltage application) used in experiment.

(Background to obtaining one embodiment of the present invention)
Prior to the description of the embodiments of the present invention, the background of obtaining one aspect of the present invention will be described.

  In a light distribution device including a liquid crystal layer, the alignment state of liquid crystal molecules in the liquid crystal layer is changed by changing a voltage applied to a pair of transparent electrodes sandwiching the liquid crystal layer. Thereby, since the refractive index of a liquid crystal layer can be changed, the light distribution device which can change the advancing direction of the incident light is realizable.

  In recent years, instead of a liquid crystal layer, a light distribution device using a nanoparticle dispersion layer in which charged nanoparticles (charged particles) are dispersed in a solvent has been studied. The nanoparticle dispersion layer is composed of, for example, charged nanoparticles made of a high refractive index material and an insulating liquid (dispersion) in which the nanoparticles are dispersed.

  In such a light distribution device including a nanoparticle dispersion layer, by changing the voltage applied to a pair of transparent electrodes sandwiching the nanoparticle dispersion layer, the nanoparticles in the nanoparticle dispersion layer are electrophoresed to generate an in-insulating liquid. Can be unevenly distributed. Thereby, since the refractive index distribution in a nanoparticle dispersion layer can be changed, the light distribution device which can change the advancing direction of the incident light is realizable.

  However, when a light distribution device including a nanoparticle dispersion layer was actually produced, it was found that the transparent electrode was colored and colored. As a cause of this, the inventors conducted experiments and intensively studied, and ascertained that the cause was that the metal material constituting the transparent electrode was dissolved in the solvent and deposited on the surface of the transparent electrode. The experiment and the examination result will be described with reference to FIGS. 5A and 5B. 5A and 5B are schematic views showing the configuration of the optical device used in this experiment. FIG. 5A shows a state before voltage application, and FIG. 5B shows a state at the time of voltage application.

In this experiment, as shown in FIG. 5A, transparent electrodes 30X and 40X made of ITO (Indium Tin Oxide) are formed on the inner surfaces of a pair of transparent substrates 10X and 20X each made of a glass substrate, and a pair of transparent electrodes A nanoparticle dispersion layer 60X was filled between 30X and 40X. As the nanoparticle dispersion layer 60X, a nanoparticle 62X made of zirconia particles composed of zirconium oxide (ZrO ₂ ) was dispersed in an insulating liquid (dispersion liquid) 61X. The nanoparticles 62X used were positively charged.

  As the insulating liquid 61X, for example, a liquid prepared by adding hydrochloric acid to an aqueous dispersion having a pH of about 7 to 8 and adjusting the pH to about 4 to 5 is replaced with a non-aqueous solvent. At this time, an elemental analysis of the component of the insulating liquid 61X and the colored transparent electrode revealed that residual acid (specifically HCl) was present in the insulating liquid 61X. And it is assumed that the transparent electrodes 30X and 40X made of ITO are partially dissolved by the residual acid.

  That is, a part of the surface layer of the transparent electrodes 30X and 40X is peeled off by the residual acid in the insulating liquid 61X, and impurity metal ions composed of the metal material of the transparent electrodes 30X and 40X exist in the insulating liquid 61. It is in a state.

Specifically, in the nanoparticle dispersion layer 60X, as shown in FIG. 5A, indium (In) and tin (Sn) constituting ITO dissolve into the insulating liquid 61, and In ions (In ³⁺ ) and Sn ions It is considered that (Sn ²⁺ ) is present in the insulating liquid 61.

  In this state, when a voltage is applied to the transparent electrodes 30X and 40X, impurity metal ions in the insulating liquid 61 are deposited, and a precipitate 90X is formed on the transparent electrodes 30X and 40X. In this experiment, as shown in FIG. 5B, when 0V was applied to the transparent electrode 30X and −20V was applied to the transparent electrode 40X, In ions and Sn ions in the insulating liquid 61 were deposited on the metal, and the low potential side A precipitate 90X appeared on the surface of the transparent electrode 40X. It is considered that the precipitate 90X becomes a colored portion (discolored portion) and the transparent electrodes 30X and 40X appear to be colored.

  As described above, in an optical device in which nanoparticles in a nanoparticle dispersion layer are electrophoresed using a transparent electrode made of ITO, the transparent electrode is colored and the optical performance is deteriorated.

  Accordingly, the present inventors have studied various measures for preventing the transparent electrode from being colored, and as a result, have found that the coloring of the transparent electrode can be suppressed by devising a material for the transparent electrode that contacts the nanoparticle dispersion layer.

  The present invention has been made based on such findings, and an object thereof is to provide an optical device having desired optical performance.

  Hereinafter, description will be given based on the embodiment of the present invention. Each of the embodiments described below shows a specific example of the present invention. Therefore, the numerical values, shapes, materials, components, component arrangement positions, connection forms, 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 schematic diagram and is not necessarily shown strictly. Accordingly, the scales and the like do not necessarily match in each drawing. In each figure, substantially the same configuration is denoted by the same reference numeral, and redundant description is omitted or simplified.

  In the present specification and drawings, the X axis, the Y axis, and the Z axis represent the three axes of the three-dimensional orthogonal coordinate system. In the present embodiment, the Z axis direction is the vertical direction and the Z axis is perpendicular to the Z axis. This direction (the direction parallel to the XY plane) is the horizontal direction. The X axis and the Y axis are orthogonal to each other and both are orthogonal to the Z axis. Note that the plus direction in the Z-axis direction is defined as a vertically downward direction. In this specification, the “thickness direction” means the thickness direction of the optical device, and is a direction perpendicular to the main surfaces of the first substrate 10 and the second substrate 20 (in this embodiment, the Y-axis direction). That is.

(Embodiment)
First, the configuration of the optical device 1 according to the embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a cross-sectional view schematically showing an optical device 1 according to an embodiment. 2 is an enlarged cross-sectional view of the optical device 1, and shows an enlarged view of a region II surrounded by a broken line in FIG.

  The optical device 1 is a light control device that controls light incident on the optical device 1. Specifically, the optical device 1 controls the traveling direction of light incident on the optical device 1. In the present embodiment, the optical device 1 is a light distribution device that can change the traveling direction of incident light (for example, distribute light) and emit the light.

  As shown in FIGS. 1 and 2, the optical device 1 includes a first substrate 10, a second substrate 20, a first electrode 30, a second electrode 40, a concavo-convex structure 50, and a refractive index variable layer 60. Is provided.

  In the optical device 1, the first electrode 30, the concavo-convex structure 50, the refractive index variable layer 60, and the second electrode 40 are arranged in this order along the thickness direction between the pair of the first substrate 10 and the second substrate 20. It becomes the composition.

  As shown in FIG. 1, in the optical device 1, the first substrate 10, the first electrode 30, and the uneven structure 50 constitute a first laminated substrate 100, and the second substrate 20 and the second electrode 40 are A two-layer substrate 200 is configured.

  The first laminated substrate 100 and the second laminated substrate 200 are arranged so as to face each other with a gap therebetween, and the entire circumference of the outer peripheral end portion is sealed. Thereby, the refractive index variable layer 60 filled between the first laminated substrate 100 and the second laminated substrate 200 can be confined. For example, a seal member such as an adhesive is formed on the inner surface along the outer peripheral edges of the first laminated substrate 100 and the second laminated substrate 200, or the first substrate 10 and the second substrate 20 are welded by a laser. By doing so, it is possible to seal the outer peripheral ends of the first laminated substrate 100 and the second laminated substrate 200.

  Hereinafter, each component of the optical device 1 will be described in detail with reference to FIGS. 1 and 2.

[First substrate, second substrate]
As shown in FIGS. 1 and 2, the first substrate 10 is a base material of the first multilayer substrate 100, and the second substrate 20 is a base material of the second multilayer substrate 200.

  The first substrate 10 and the second substrate 20 are light-transmitting substrates (translucent substrates). The first substrate 10 and the second substrate 20 may be transparent transparent substrates.

  As the first substrate 10 and the second substrate 20, for example, a resin substrate made of a resin material or a glass substrate made of a glass material can be used. Examples of the resin substrate material include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate (PC), acrylic, and epoxy. Examples of the glass substrate material include soda glass, non-alkali glass, and high refractive index glass. The resin substrate has an advantage of less scattering at the time of destruction. On the other hand, the glass substrate has an advantage of high light transmittance and low moisture permeability.

  Although the 1st board | substrate 10 and the 2nd board | substrate 20 may be comprised with the same material and may be comprised with a different material, it is better to be comprised with the same material. Moreover, the 1st board | substrate 10 and the 2nd board | substrate 20 are not restricted to a rigid board | substrate, A flexible substrate or a film substrate may be sufficient. In the present embodiment, a transparent resin substrate (PET substrate) made of PET is used as each of the first substrate 10 and the second substrate 20.

  Although the thickness of the 1st board | substrate 10 and the 2nd board | substrate 20 is 5 micrometers-3 mm, for example, it does not restrict to this. In the present embodiment, the thicknesses of the first substrate 10 and the second substrate 20 are both 50 μm.

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

[First electrode, second electrode]
The first electrode 30 and the second electrode 40 are translucent electrodes and transmit incident light. The first electrode 30 and the second electrode 40 are transparent electrodes made of, for example, a transparent conductive layer.

  Further, at least one of the first electrode 30 and the second electrode 40 is made of a metal having a smaller ionization tendency than hydrogen (H). In the present embodiment, both the first electrode 30 and the second electrode 40 are made of a metal that has a smaller ionization tendency than hydrogen. When the first electrode 30 and the second electrode 40 are made of a transparent electrode and are made of a metal having a smaller ionization tendency than hydrogen, the metal constituting the first electrode 30 and the second electrode 40 is copper (Cu). At least one selected from silver (Ag), platinum (Pt), and gold (Au) can be used. These metals can be made into transparent electrodes by thinning them to a thickness of at least about 25 nm to 250 nm. In this case, the first electrode 30 and the second electrode 40 may be solid electrodes of a thin film having a rectangular shape in plan view formed on almost the entire surface of each of the first substrate 10 and the second substrate 20. However, pattern electrodes, such as a metal mesh (for example, copper mesh) or a nanowire (for example, silver nanowire), may be sufficient. In addition, the film thickness of the 1st electrode 30 and the 2nd electrode 40 is not limited to said numerical range. Further, the shapes of the first electrode 30 and the second electrode 40 are not limited to those described above.

  The first electrode 30 and the second electrode 40 may have a single layer structure using only one kind of the above metals, or a plurality of metal layers each composed of a plurality of different metals are laminated. It may be a laminated structure.

  As shown in FIGS. 1 and 2, the first electrode 30 and the second electrode 40 are electrically paired so that an electric field can be applied to the refractive index variable layer 60. The first electrode 30 and the second electrode 40 are also paired in terms of arrangement, and are arranged so as to face each other.

  The first electrode 30 is disposed on the second substrate 20 side of the first substrate 10. The second electrode 40 is disposed on the first substrate 10 side of the second substrate 20. Specifically, the first electrode 30 is formed on the main surface of the first substrate 10 on the second substrate 20 side, and the second electrode 40 is formed on the main surface of the second substrate 20 on the first substrate 10 side. Is formed.

  Further, in the present embodiment, the first electrode 30 and the second electrode 40 that form a pair are interposed between the first substrate 10 and the second substrate 20 so as to sandwich at least the uneven structure 50 and the refractive index variable layer 60. Has been placed. Specifically, the first electrode 30 is disposed between the first substrate 10 and the concavo-convex structure 50, and the second electrode 40 is disposed between the second substrate 20 and the refractive index variable layer 60. ing.

  In the present embodiment, the first electrode 30 and the second electrode 40 are in contact with the refractive index variable layer 60. Specifically, the first electrode 30 and the second electrode 40 are in contact with the insulating liquid 61 of the refractive index variable layer 60. Specifically, the entire surfaces of the first electrode 30 and the second electrode 40 are in contact with the insulating liquid 61.

  In addition, the 1st electrode 30 and the 2nd electrode 40 are comprised so that electrical connection with an external power supply is attained. For example, each of the first electrode 30 and the second electrode 40 is drawn out to the outside of the sealing resin that seals the refractive index variable layer 60, and this drawn portion is used as an electrode terminal for connecting to an external power source. Also good.

[Uneven structure]
As shown in FIGS. 1 and 2, the concavo-convex structure 50 is a concavo-convex layer having a concavo-convex surface, and has a configuration in which a plurality of convex portions 51 of micro-order size or nano-order size are arranged.

  The concavo-convex structure 50 is disposed on the second substrate 20 side of the first substrate 10. In the present embodiment, the concavo-convex structure 50 is disposed on the second substrate 20 side of the first electrode 30. Specifically, the concavo-convex structure 50 is provided on the main surface of the first electrode 30 on the second substrate 20 side.

  In the present embodiment, the concavo-convex structure 50 is provided on the first electrode 30 such that the plurality of convex portions 51 protrude toward the refractive index variable layer 60 side. In this case, an adhesion layer may be formed between the first electrode 30 and the concavo-convex structure 50. The surface on the first electrode 30 side of the concavo-convex structure 50 (the surface on the first electrode 30 side of the convex portion 51) is a flat surface.

  Moreover, the some convex part 51 is formed in stripe form. Specifically, each of the plurality of protrusions 51 has a trapezoidal cross-sectional shape and is a long, substantially quadrangular prism shape extending in the X-axis direction, and is arranged at equal intervals along the Z-axis direction. . Moreover, although all the convex parts 51 become the same shape, it does not restrict to this.

  For example, each convex portion 51 has a height of 100 nm to 100 μm and an aspect ratio (height / lower bottom) of about 1 to 10, but is not limited thereto. As an example, each convex portion 51 has a height of about 10 μm, a lower base of about 5 μm, and an upper base of about 2 μm.

  Moreover, the space | interval of the two convex parts 51 adjacent to a Z-axis direction is 0 or more and 100 mm or less, for example. That is, the two convex portions 51 adjacent to each other in the Z-axis direction may be disposed with a predetermined interval without contacting the bottom portion, or may be disposed with the bottom portion in contact (with a spacing of zero). However, the interval between the two convex portions 51 adjacent in the Z-axis direction is preferably equal to or less than the bottom of the convex portion 51. As an example, in the case of the above-described convex portions 51 (height 10 μm, lower base 5 μm, upper base 2 μm), the interval between two adjacent convex portions 51 is about 2 μm.

  Each of the plurality of convex portions 51 has a pair of side surfaces. In the present embodiment, the cross-sectional shape of each convex portion 51 is a tapered shape that tapers along the direction from the second substrate 20 toward the first substrate 10 (the Y-axis minus direction). Therefore, each of the pair of side surfaces of each convex portion 51 is an inclined surface inclined at a predetermined inclination angle with respect to the thickness direction, and the interval between the pair of side surfaces in each convex portion 51 (width of the convex portion 51). Is gradually smaller from the second substrate 20 toward the first substrate 10. The inclination angles of the two side surfaces of each convex portion 51 may be the same or different. In the present embodiment, the inclination angles (base angles) of the two side surfaces of each convex portion 51 are the same.

  A pair of side surfaces of each convex portion 51 is a surface in contact with the refractive index variable layer 60, and light incident from the first substrate 10 receives an optical action on the pair of side surfaces of the convex portion 51.

  Specifically, in each of the pair of side surfaces of the convex portion 51, the light incident from the first substrate 10 is refracted and transmitted according to the refractive index difference between the convex portion 51 and the refractive index variable layer 60. The light is transmitted without being refracted or totally reflected. That is, the pair of side surfaces of the convex portion 51 can be a refractive surface or a total reflection surface, depending on the refractive index difference between the convex portion 51 and the refractive index variable layer 60 and the incident angle of light. Thereby, the concavo-convex structure 50 (convex portion 51) distributes light incident from the first substrate 10.

  As a material of the concavo-convex structure 50 (convex portion 51), for example, a resin material having translucency such as an acrylic resin, an epoxy resin, or a silicone resin can be used. The uneven structure 50 can be formed by, for example, laser processing or imprinting. In the present embodiment, the concavo-convex structure 50 is formed using an acrylic resin having a refractive index of about 1.5.

  Note that the concavo-convex structure 50 may be made of only an insulating resin material as long as it can apply an electric field to the refractive index variable layer 60 by the first electrode 30 and the second electrode 40. You may have. In this case, the material of the concavo-convex structure 50 may be a conductive polymer such as PEDOT, or a resin (conductor containing resin) containing a conductor.

[Refractive index variable layer]
As shown in FIGS. 1 and 2, the refractive index variable layer 60 includes an insulating liquid 61 and nanoparticles 62 contained in the insulating liquid 61. The refractive index variable layer 60 is a nanoparticle dispersion layer in which countless nanoparticles 62 are dispersed in an insulating liquid 61.

  The insulating liquid 61 is a transparent liquid having insulating properties, and is a solvent serving as a dispersion medium in which the nanoparticles 62 are dispersed as a dispersoid. As the insulating liquid 61, for example, a liquid having a refractive index (solvent refractive index) of about 1.3 to about 1.5 can be used. In the present embodiment, the insulating liquid 61 having a refractive index of about 1.4 is used.

The kinematic viscosity of the insulating liquid 61 is preferably about 100 mm ² / s. The insulating liquid 61 preferably has a low dielectric constant (below the dielectric constant of the concavo-convex structure 50), non-flammability (high flash point having a flash point of 250 ° C. or higher), and low volatility. Specifically, the insulating liquid 61 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 61 is a halogenated carbon hydrogen such as a fluorocarbon hydrogen. Such an insulating liquid 61 can be produced by substituting an aqueous dispersion whose pH is adjusted to about 4 to 5 with an acid such as hydrochloric acid with a non-aqueous solvent. For example, hydrochloric acid is added to an aqueous dispersion having a pH of about 7 to 8 to adjust the pH so that the pH is about 4 to 5, and the acidic aqueous dispersion having a pH of 4 to 5 is replaced with a non-aqueous solvent. By doing so, the insulating liquid 61 can be obtained.

  A plurality of nanoparticles 62 are dispersed in the insulating liquid 61. The nanoparticle 62 is a fine particle having a particle size of nano-order size. Specifically, when the wavelength of incident light is λ, the particle size of the nanoparticles 62 is preferably λ / 4 or less. By setting the particle size of the nanoparticles 62 to λ / 4 or less, light scattering at the nanoparticles 62 can be reduced, and an average refractive index between the nanoparticles 62 and the insulating liquid 61 can be obtained. The particle size of the nanoparticles 62 is preferably as small as possible, preferably 100 nm or less, more preferably several nm to several tens nm.

  The nanoparticles 62 may be made of a high refractive index material. Specifically, the refractive index of the nanoparticles 62 is higher than the refractive index of the insulating liquid 61. In the present embodiment, the refractive index of the nanoparticles 62 is higher than the refractive index of the concavo-convex structure 50.

As the nanoparticles 62, inorganic fine particles such as metal oxide fine particles can be used. Moreover, the nanoparticle 62 is good to be comprised with the material with a high transmittance | permeability. In the present embodiment, transparent zirconia particles having a refractive index of 2.13 and made of zirconium oxide (ZrO ₂ ) are used as the nanoparticles 62. The material of the nanoparticles 62 is not limited to zirconium oxide, and may be composed of transparent metal oxide fine particles such as titanium oxide or aluminum oxide.

  In the refractive index variable layer 60, the nanoparticles 62 are dispersed throughout the insulating liquid 61 so as to have a desired refractive index. In the present embodiment, the refractive index (average refractive index) of the entire refractive index variable layer 60 is substantially the same as the refractive index of the concavo-convex structure 50 in a state where the nanoparticles 62 are uniformly dispersed in the insulating liquid 61. Is set. Specifically, the refractive index of the entire refractive index variable layer 60 is adjusted to be about 1.5. The refractive index of the entire refractive index variable layer 60 can be adjusted by adjusting the concentration (amount) of the nanoparticles 62 dispersed in the insulating liquid 61. In addition, the amount of the nanoparticles 62 may be set so as to be buried in the concave portion of the concavo-convex structure 50 (region between two adjacent convex portions 51). In this case, the concentration of the nanoparticles 62 with respect to the insulating liquid 61 is about 10%. % To 30%.

  The refractive index variable layer 60 configured in this way is disposed between the concavo-convex structure 50 and the second electrode 40. Specifically, the refractive index variable layer 60 is in contact with the uneven structure 50. That is, the contact surface of the refractive index variable layer 60 with the concave / convex surface of the concave / convex structure 50 is an interface between the refractive index variable layer 60 and the concave / convex surface of the concave / convex structure 50. The refractive index variable layer 60 is also in contact with the second electrode 40, but another layer (film) may be interposed between the refractive index variable layer 60 and the second electrode 40.

  Moreover, the refractive index of the refractive index variable layer 60 changes according to the voltage applied between the first electrode 30 and the second electrode 40. Specifically, the refractive index variable layer 60 is disposed between the first electrode 30 and the second electrode 40, and a voltage is applied between the first electrode 30 and the second electrode 40. An electric field is applied to the refractive index variable layer 60. For example, a DC voltage is applied between the first electrode 30 and the second electrode 40.

  Since the nanoparticles 62 dispersed in the insulating liquid 61 are charged, when an electric field is applied to the refractive index variable layer 60, the nanoparticles 62 migrate in the insulating liquid 61 in accordance with the electric field distribution, and thus the insulating properties. It is unevenly distributed in the liquid 61. Thereby, the particle distribution of the nanoparticles 62 in the refractive index variable layer 60 can be changed to give the concentration distribution of the nanoparticles 62 in the refractive index variable layer 60, so that the refractive index in the refractive index variable layer 60 can be obtained. Distribution changes. That is, the refractive index of the refractive index variable layer 60 partially changes. Thus, the refractive index variable layer 60 mainly functions as a refractive index adjustment layer capable of adjusting the refractive index with respect to light in the visible light region.

  The refractive index variable layer 60 configured as described above is disposed between the first laminated substrate 100 and the second laminated substrate 200. Specifically, the insulating liquid 61 in which the nanoparticles 62 are dispersed is sealed between the first laminated substrate 100 and the second laminated substrate 200.

  The thickness of the refractive index variable layer 60 (that is, the gap between the first laminated substrate 100 and the second laminated substrate 200) is, for example, 1 μm to 100 μm, but is not limited thereto. As an example, when the height of the convex portion 51 of the concavo-convex structure 50 is 10 μm, the thickness of the refractive index variable layer 60 is, for example, 40 μm.

[Optical device manufacturing method]
Next, a method for manufacturing the optical device 1 will be described with reference to FIGS.

  First, for example, a PET substrate is used as the first substrate 10, an ITO film is formed as the first electrode 30 on the PET substrate, and a plurality of acrylic resins (refractive index 1.5) are formed on the ITO film. The first laminated substrate 100 is produced by forming the concavo-convex structure 50 including the convex portions 51 by the imprint method.

  Next, for example, a PET substrate is used as the second substrate 20, and the second electrode 40 made of an ITO film is formed on the PET substrate, whereby the second laminated substrate 200 is manufactured.

  Next, an insulating liquid 61 in which nanoparticles 62 are dispersed is filled as the refractive index variable layer 60 between the first laminated substrate 100 and the second laminated substrate 200, and the first laminated substrate 100 and the second laminated substrate 200 are filled with the second laminated substrate 200. The refractive index variable layer 60 is sealed between the first laminated substrate 100 and the second laminated substrate 200 by bonding the outer peripheral portion with the laminated substrate 200.

  In this way, the optical device 1 having the structure shown in FIG. 1 can be manufactured.

[Optical action of optical device]
Next, the optical action of the optical device 1 according to the embodiment will be described with reference to FIGS. 3A to 3C. 3A is a diagram for explaining the first optical action of the optical device 1 according to the embodiment, and FIG. 3B is a diagram for explaining the second optical action of the optical device 1, and FIG. FIG. 4 is a diagram for explaining a third optical action of the optical device 1.

  The optical device 1 can be realized, for example, as a window with a light distribution control function by being installed in a building window. The optical device 1 is bonded to a building window via an adhesive layer, for example. In this case, the optical device 1 is installed in the window so that the longitudinal direction of the convex portion 51 of the concavo-convex structure 50 is the horizontal direction. For example, sunlight is incident on the optical device 1 installed in the window. In the present embodiment, since the optical device 1 is installed so that the first substrate 10 is located on the light incident side (outside of the building), the optical device 1 receives light (sunlight from the first substrate 10). ) And can be emitted from the second substrate 20 to the inside of the building of the optical device 1 (for example, indoors).

  At this time, the light incident on the optical device 1 receives an optical action from the optical device 1 when passing through the optical device 1. Specifically, the optical action of the optical device 1 changes due to the change in the refractive index of the refractive index variable layer 60. For this reason, the light incident on the optical device 1 is subjected to different optical actions according to the refractive index of the refractive index variable layer 60, and the traveling direction is controlled according to the refractive index of the refractive index variable layer 60.

  In the present embodiment, the optical device 1 can control the traveling direction of light incident on the optical device 1 according to the voltage applied between the first electrode 30 and the second electrode 40. Specifically, the particle distribution of the nanoparticles 62 in the refractive index variable layer 60 (nanoparticle dispersion layer) changes according to the voltage applied between the first electrode 30 and the second electrode 40, thereby The refractive index of the refractive index variable layer 60 partially changes. As a result, the optical action of the optical device 1 changes. Hereinafter, the optical action of the optical device 1 will be described in detail.

  First, the first optical action of the optical device 1 will be described with reference to FIG. 3A. When no potential is applied to the first electrode 30 and the second electrode 40, that is, when no voltage is applied between the first electrode 30 and the second electrode 40 (when no voltage is applied), optical The device 1 is in the first optical mode and gives a first optical action to incident light.

  In the first optical mode, since no electric field is applied to the refractive index variable layer 60, the nanoparticles 62 are dispersed throughout the insulating liquid 61 in the variable refractive index layer 60 as shown in FIG. 3A. . That is, the nanoparticles 62 are in an equally dispersed state in the insulating liquid 61.

  At this time, in the present embodiment, as described above, the refractive index of the refractive index variable layer 60 in a state where the nanoparticles 62 are dispersed throughout the insulating liquid 61 is about 1.5. Moreover, the refractive index of the concavo-convex structure 50 is about 1.5. Therefore, when no voltage is applied between the first electrode 30 and the second electrode 40 (in the first optical mode), the refractive index of the entire refractive index variable layer 60 is substantially the same as the refractive index of the concavo-convex structure 50. It becomes. As a result, the refractive index difference between the concavo-convex structure 50 (convex portion 51) and the refractive index variable layer 60 is almost eliminated (refractive index difference Δn≈0).

  In this case, as shown in FIG. 3A, when light L is incident on the optical device 1 from an oblique direction, there is no refractive index difference at the interface between the concavo-convex structure 50 (convex portion 51) and the refractive index variable layer 60. The light L incident on the optical device 1 is not refracted at the interface between the refractive index variable layer 60 and the side surface of the convex portion 51 and does not change its traveling direction. Therefore, in the first optical mode, the light L incident on the optical device 1 travels straight through the optical device 1 without being bent in the traveling direction by the optical device 1 and is emitted to the outside of the optical device 1.

  As described above, when no voltage is applied between the first electrode 30 and the second electrode 40, the optical device 1 causes the light incident on the first substrate 10 to travel straight and transmit the second substrate 20. . That is, the first optical mode is a transparent mode, and the optical device 1 is in a transparent state in the first optical mode. In this case, the light incident on the first substrate 10 is transmitted straight through without being distributed by the optical device 1 and is emitted from the second substrate 20.

  Although not shown in detail, there is a difference in refractive index at the interface between each member such as the interface between the first substrate 10 and the first electrode 30 or the interface between the refractive index variable layer 60 and the second electrode 40. In the place, the light incident from the first substrate 10 is refracted at the interface. However, the first substrate 10 and the second substrate 20 are the same material (that is, the refractive index is the same), and the first electrode 30 and the second electrode 40 are the same material (that is, the refractive index is the same). For this reason, the light incident from the first substrate 10 and emitted from the second substrate 20 is emitted from the second substrate 20 and the incident angle when entering the first substrate 10 in the first optical mode (transparent mode). The exit angle when doing this is the same. That is, the angle of the traveling direction of the light L does not change before the light L enters the optical device 1 and after the light L exits the optical device 1.

  In the first optical mode, the refractive index of the refractive index variable layer 60 as a whole and the refractive index of the concavo-convex structure 50 are substantially the same. More preferably, it is 0.005 or less (Δn ≦ 0.005). If the refractive index difference between the refractive index variable layer 60 and the concavo-convex structure 50 exceeds 0.005, light may be scattered at the interface between the refractive index variable layer 60 and the concavo-convex structure 50, and haze may occur.

  Next, the second optical action of the optical device 1 will be described with reference to FIG. 3B. When the first voltage is applied between the first electrode 30 and the second electrode 40 (when the first voltage is applied), the optical device 1 enters the second optical mode, and the second is applied to the incident light. Provides optical action. Specifically, a DC voltage is applied between the first electrode 30 and the second electrode 40. In this case, the voltage (potential difference) applied between the first electrode 30 and the second electrode 40 is, for example, about several tens V (for example, 20 V).

  In the second optical mode, since an electric field is applied to the refractive index variable layer 60 by applying a DC voltage between the first electrode 30 and the second electrode 40, the refractive index variable layer 60 has charged nanoparticles. 62 migrates in the insulating liquid 61 according to the electric field distribution. That is, the nanoparticles 62 are electrophoresed in the insulating liquid 61.

  Specifically, when the nanoparticles 62 are positively charged, when a negative potential is applied to the first electrode 30 and a positive potential is applied to the second electrode 40, the positively charged nanoparticles 62 are It migrates toward the electrode 30 and is aggregated and unevenly distributed on the concave-convex structure 50 side in the refractive index variable layer 60. At this time, the nanoparticles 62 that migrate toward the first electrode 30 enter and accumulate in the recesses of the concavo-convex structure 50, that is, in the region between the two adjacent protrusions 51.

  As described above, the nanoparticles 62 are unevenly distributed on the uneven structure 50 side in the refractive index variable layer 60, whereby the particle distribution of the nanoparticles 62 is changed and the refractive index distribution in the refractive index variable layer 60 is not uniform. . Specifically, in the refractive index variable layer 60, the first region 60a on the concave-convex structure 50 side where the nanoparticles 62 are gathered by migration of the whole nanoparticles 62 and the concentration of the nanoparticles 62 is increased, and the nanoparticles As a result of migration of the entire 62, the second region 60b on the second electrode 40 side in which the nanoparticles 62 are eliminated and the concentration of the nanoparticles 62 is reduced is generated.

  In this case, since the refractive index of the nanoparticles 62 is higher than the refractive index of the insulating liquid 61, the refractive index of the first region 60 a on the concave-convex structure 50 side of the refractive index variable layer 60 is the second index of the refractive index variable layer 60. It becomes higher than the refractive index of the second region 60b on the electrode 40 side. Therefore, in the refractive index variable layer 60, a high refractive index first region 60a on the concave-convex structure 50 side and a low refractive index second region 60b on the second electrode 40 side are generated.

  In the present embodiment, since the refractive index of the entire refractive index variable layer 60 when no voltage is applied is about 1.5, the first region on the concave-convex structure 50 side of the refractive index variable layer 60 when the first voltage is applied. The refractive index of 60a is distributed at about 1.8 to about 1.6 in the thickness direction, and the refractive index of the second region 60b on the second electrode 40 side of the refractive index variable layer 60 is about 1.6 in the thickness direction. It is distributed at about 1.4.

  Thereby, as described above, since the refractive index of the concavo-convex structure 50 is about 1.5, the first voltage is applied between the first electrode 30 and the second electrode 40 in the second optical mode. Between the refractive index of the concavo-convex structure 50 (about 1.5) and the refractive index of the first region 60a on the concavo-convex structure 50 side of the refractive index variable layer 60 (about 1.6 to about 1.8). Causes a difference in refractive index.

  In this case, as shown in FIG. 3B, when the light L is incident on the optical device 1 from an oblique direction, there is a refractive index difference at the interface between the concavo-convex structure 50 (convex portion 51) and the refractive index variable layer 60. The light L is refracted at the interface between the lower side surface of the convex portion 51 and the refractive index variable layer 60 and then totally reflected at the interface between the upper side surface of the lower convex portion 51 and the refractive index variable layer 60. Then, the traveling direction is bent in the direction of rebound and the light is emitted to the outside of the optical device 1. That is, the light L incident on the optical device 1 is distributed by the optical device 1 at an angle different from that when no voltage is applied.

  As described above, when the first voltage is applied between the first electrode 30 and the second electrode 40, the optical device 1 distributes the light incident on the first substrate 10 and distributes the second substrate 20. Make it transparent. That is, the second optical mode is a light distribution mode, and the optical device 1 is in a light distribution state in the second optical mode. In this case, the light incident on the first substrate 10 is reflected by the concavo-convex structure 50 of the optical device 1 as described above, and the traveling direction is changed and is emitted from the second substrate 20.

  Although not shown in detail, even in the second optical mode, the interface between the members, such as the interface between the first substrate 10 and the first electrode 30 or the interface between the refractive index variable layer 60 and the second electrode 40, etc. In a portion where there is a difference in refractive index at the interface, the light incident from the first substrate 10 is refracted at the interface as described above.

  In addition, when the potential applied to the first electrode 30 and the second electrode 40 is set to zero and no voltage is applied, the nanoparticles 62 migrate in the insulating liquid 61, and as shown in FIG. Returns to the state in which it is uniformly dispersed throughout the insulating liquid 61.

  On the other hand, when a second voltage reverse to the first voltage is applied between the first electrode 30 and the second electrode 40 (when the second voltage is applied), the optical device 1 is in the first optical mode. The third optical mode is different from the (when no voltage is applied) and the second optical mode (when the first voltage is applied), and the third optical action is given to the incident light.

  Hereinafter, the third optical action of the optical device 1 will be described with reference to FIG. 3C. When a second voltage reverse to the first voltage is applied between the first electrode 30 and the second electrode 40 (when the second voltage is applied), the optical device 1 is in the third optical mode, A third optical action is given to the incident light. Specifically, a DC voltage that is a reverse bias to the first voltage is applied between the first electrode 30 and the second electrode 40 as the second voltage. For example, when the first voltage is + 20V, the second voltage is −20V.

  In the third optical mode, as in the second optical mode, an electric field is applied to the refractive index variable layer 60 in accordance with the voltage applied between the first electrode 30 and the second electrode 40. Therefore, the refractive index variable layer In 60, the charged nanoparticles 62 are electrophoresed in the insulating liquid 61 according to the electric field distribution.

  Specifically, when a positive potential is applied to the first electrode 30 and a negative potential is applied to the second electrode 40, the positively charged nanoparticles 62 migrate toward the second electrode 40, and the refractive index variable layer. 60 is aggregated and unevenly distributed on the second electrode 40 side.

  As described above, the nanoparticles 62 are unevenly distributed on the second electrode 40 side in the refractive index variable layer 60, whereby the particle distribution of the nanoparticles 62 is changed and the refractive index distribution in the refractive index variable layer 60 is not uniform. Disappear. Specifically, in the refractive index variable layer 60, the first region 60a on the second electrode 40 side where the nanoparticles 62 are gathered by migration of the entire nanoparticles 62 and the concentration of the nanoparticles 62 is increased, Due to the migration of the entire particle 62, the second region 60b on the concave-convex structure 50 side in which the nanoparticle 62 is eliminated and the concentration of the nanoparticle 62 is reduced is generated.

  In this case, since the refractive index of the nanoparticles 62 is higher than the refractive index of the insulating liquid 61, the refractive index of the first region 60 a on the second electrode 40 side of the refractive index variable layer 60 is the unevenness of the refractive index variable layer 60. The refractive index of the second region 60b on the structure 50 side is higher. In other words, the refractive index of the second region 60 b on the concave-convex structure 50 side of the refractive index variable layer 60 is lower than the refractive index of the first region 60 a on the second electrode 40 side of the refractive index variable layer 60. Therefore, in the refractive index variable layer 60, the high refractive index first region 60a on the second electrode 40 side and the low refractive index second region 60b on the concave-convex structure 50 side are generated.

  In this embodiment, since the refractive index of the entire refractive index variable layer 60 when no voltage is applied is about 1.5, the first electrode on the second electrode 40 side of the refractive index variable layer 60 when the second voltage is applied. The refractive index of the region 60a is distributed at about 1.6 to about 1.8 in the thickness direction, and the refractive index of the second region 60b on the uneven structure 50 side of the refractive index variable layer 60 is about 1.4 in the thickness direction. It is distributed at about 1.5.

  Thereby, as described above, since the refractive index of the concavo-convex structure 50 is about 1.5, in the case of the third optical mode (a second voltage is applied between the first electrode 30 and the second electrode 40). Between the refractive index of the concavo-convex structure 50 (about 1.5) and the refractive index of the second region 60b on the concavo-convex structure 50 side of the refractive index variable layer 60 (about 1.4 to about 1.5). Causes a difference in refractive index.

  In this case, as shown in FIG. 3C, when light L is incident on the optical device 1 from an oblique direction, there is a difference in refractive index at the interface between the concavo-convex structure 50 (convex portion 51) and the refractive index variable layer 60. The light L is incident on the concavo-convex structure 50 (the convex portion 51), and at the interface between the upper side surface of the convex portion 51 (particularly, the side surface from the first electrode 30 side of the convex portion 51) and the refractive index variable layer 60. After the traveling direction is bent in the direction of total reflection and rebound, the light is refracted at the interface between the upper side surface of the convex portion 51 and the refractive index variable layer 60 and is emitted to the outside of the optical device 1. That is, the light L incident on the optical device 1 is distributed by the optical device 1 at an angle different from that when no voltage is applied and when the first voltage is applied.

  Thus, even when the second voltage is applied between the first electrode 30 and the second electrode 40, the optical device 1 distributes the light incident on the first substrate 10 and distributes the second substrate 20. Permeate. That is, the third optical mode is also a light distribution mode like the second optical mode, and the optical device 1 is in a light distribution state in the third optical mode. In this case, the light incident on the first substrate 10 is reflected by the concavo-convex structure 50 of the optical device 1 as described above, and the traveling direction is changed and is emitted from the second substrate 20.

  Although not shown in detail, even in the third optical mode, the interface between the members, such as the interface between the first substrate 10 and the first electrode 30 or the interface between the refractive index variable layer 60 and the second electrode 40, etc. In a portion where there is a difference in refractive index at the interface, the light incident from the first substrate 10 is refracted at the interface as described above.

  In addition, when the potential applied to the first electrode 30 and the second electrode 40 is set to zero and no voltage is applied, the nanoparticles 62 migrate in the insulating liquid 61, and as shown in FIG. Returns to the state in which it is uniformly dispersed throughout the insulating liquid 61. On the other hand, when the voltage applied between the first electrode 30 and the second electrode 40 is switched from the second voltage to the first voltage, the nanoparticles 62 migrate in the reverse direction in the insulating liquid 61, as shown in FIG. 3B. As shown, the nanoparticles 62 return to a uniformly dispersed state throughout the insulating liquid 61.

  The optical device 1 configured as described above is a current-driven device. Therefore, while a voltage is applied to the first electrode 30 and the second electrode 40, a current also flows through the dispersion liquid (insulating liquid 61).

  The optical device 1 is an active optical control device that can change the optical action by controlling the refractive index matching between the concavo-convex structure 50 and the refractive index variable layer 60 by an electric field. That is, the optical device 1 can be switched to a plurality of optical modes by controlling the voltage applied between the first electrode 30 and the second electrode 40. In the present embodiment, the optical device 1 is switched to three modes: a first optical mode (transparent mode), a second optical mode (first light distribution mode), and a third optical mode (second light distribution mode). Can do.

  When the optical device 1 configured in this way is installed in a window of a building, in the first optical mode, sunlight traveling from the outside to the room can be caused to travel straight toward the floor as it is, and the second optical mode and the first In the three-optical mode, it is possible to distribute sunlight from the outdoor to the indoor toward the ceiling. That is, the second optical mode and the third optical mode are daylighting modes capable of daylighting the indoor ceiling.

  In addition, a plurality of intermediate modes are set between the first optical mode and the second optical mode or the third optical mode by switching the voltage applied between the first electrode 30 and the second electrode 40 stepwise. It is also possible to set a plurality of intermediate modes between the second optical mode and the third optical mode. Alternatively, the voltage distribution state is gradually changed between the first optical mode and the second optical mode or the third optical mode by changing the voltage applied between the first electrode 30 and the second electrode 40 in an analog manner. Or the light distribution state can be gradually changed between the second optical mode and the third optical mode.

[Summary]
As described above, according to the optical device 1 according to the present embodiment, the concavo-convex structure 50 and the refractive index variable layer 60 are disposed between the first electrode 30 and the second electrode 40. As the refractive index variable layer 60, An insulating liquid 61 in which charged nanoparticles 62 are dispersed is used.

  With this configuration, since the nanoparticles 62 migrate in the insulating liquid 61 by applying a voltage between the first electrode 30 and the second electrode 40, the refractive index of the refractive index variable layer 60 can be changed. it can. Specifically, the particle distribution of the nanoparticles 62 in the refractive index variable layer 60 changes, and the refractive index distribution of the refractive index variable layer 60 changes. Thereby, since the refractive index difference between the concavo-convex structure 50 and the refractive index variable layer 60 changes, the traveling direction of the light incident on the optical device 1 can be controlled.

  The optical device 1 in this embodiment configured as described above has a larger difference in refractive index (Δn) between the concavo-convex structure 50 and the refractive index variable layer 60 than an optical device in which the refractive index variable layer is a liquid crystal layer. Therefore, the light distribution control range can be increased. That is, the range of the light distribution angle can be expanded.

  Moreover, the optical device 1 in this Embodiment can improve a light distribution rate compared with the optical device whose refractive index variable layer is a liquid crystal layer. That is, since the liquid crystal layer is composed of liquid crystal molecules having birefringence, an optical device using the liquid crystal layer can distribute only one of the S wave and the P wave. On the other hand, since the insulating liquid 61 and the nanoparticles 62 are independent of the S wave and the P wave, the optical device 1 in the present embodiment is free from both the S wave and the P wave. Can distribute light. Therefore, the optical device 1 in the present embodiment has a light distribution rate twice that of the optical device using the liquid crystal layer.

  Thus, according to the optical device 1 in the present embodiment, the light distribution control range can be increased and the light distribution rate can be improved as compared with the optical device in which the refractive index variable layer is a liquid crystal layer. Can do. Therefore, the optical device 1 having excellent light distribution performance can be realized.

  Moreover, in the optical device 1 according to the present embodiment, at least one of the first electrode 30 and the second electrode 40 is made of a metal having a smaller ionization tendency than hydrogen. Specifically, the first electrode 30 and the second electrode 40 are made of at least one metal selected from copper, silver, platinum, and gold.

  As a result, even if the metal constituting the first electrode 30 and the second electrode 40 is dissolved in the insulating liquid 61 and the impurity metal ions are present in the insulating liquid 61 as shown in FIG. When a voltage is applied to the first electrode 30 and the second electrode 40, the impurity metal ions are deposited on the surfaces of the first electrode 30 and the second electrode 40, and the first electrode 30 and the second electrode 40. It can suppress that the colored layer by a deposit forms on the surface. That is, coloring of the first electrode 30 and the second electrode 40 can be suppressed. Therefore, the optical device 1 having excellent optical performance can be realized.

  In particular, in the present embodiment, both the first electrode 30 and the second electrode 40 are made of a metal that has a smaller ionization tendency than hydrogen.

  Thereby, about both the 1st electrode 30 and the 2nd electrode 40, it can suppress that the deposit by metal precipitation forms on the surface of the 1st electrode 30 and the 2nd electrode 40. FIG. Accordingly, it is possible to realize the optical device 1 having more excellent optical performance.

Further, since the metal constituting the first electrode 30 and the second electrode 40 is to prevent itself seep into the insulating liquid 61, the surface of the first electrode 30 and second electrode 40 such as a SiO ₂ film passivation Although a method of covering with a film is also conceivable, the optical device 1 in the present embodiment is a current-driven type device that causes the nanoparticles 62 to be electrophoresed. Therefore, the first electrode 30 and the second electrode 40 are insulative passivation. If covered with a film, the electrophoresis of the nanoparticles 62 will be hindered.

  Therefore, in the optical device 1 in the present embodiment, the first electrode 30 and the second electrode 40 are not covered with the insulating passivation film, and the first electrode 30 and the second electrode 40 are made of an insulating liquid. Touching. Specifically, the entire surfaces of the first electrode 30 and the second electrode 40 are in contact with the insulating liquid 61. For this reason, an electrical path between the first electrode 30 and the second electrode 40 via the insulating liquid 61 can be secured.

  Thereby, not only the coloring of the first electrode 30 and the second electrode 40 can be suppressed and the optical device 1 having excellent optical performance can be realized, but also the nanoparticles 62 can be efficiently electrophoresed by current drive. The optical device 1 excellent in optical performance can be realized.

  Further, from the viewpoint of suppressing the metal constituting the first electrode 30 and the second electrode 40 from dissolving into the insulating liquid 61, at least the surface layer (that is, the insulating property) of the first electrode 30 and the second electrode 40. It is only necessary that the portion in contact with the liquid 61 is made of a metal having a smaller ionization tendency than hydrogen. Therefore, the first electrode 30 and the second electrode 40 have a conductive layer made of a conductive material (ITO or the like) from which impurity metal ions dissolved in the insulating liquid 61 can be deposited by voltage application. In this case, the conductive layer may be covered with a metal layer made of a metal having a smaller ionization tendency than hydrogen so as not to contact the insulating liquid 61. That is, the first electrode 30 and the second electrode 40 may have a stacked structure of a conductive layer made of ITO or the like and a metal layer made of a metal having a smaller ionization tendency than hydrogen. In addition, the 1st electrode 30 and the 2nd electrode 40 may be comprised only with the metal whose ionization tendency is smaller than hydrogen.

  In addition, when a voltage is applied to the first electrode 30 and the second electrode 40 sandwiching the refractive index variable layer 60, the metal ions in the insulating liquid 61 are low potentials in the first electrode 30 and the second electrode 40. Metal deposition occurs at the electrode on the side. Therefore, when one of the first electrode 30 and the second electrode 40 is always used as an electrode on the low potential side (for example, when only the first optical mode and the second optical mode are not present), the low potential is low. Only the electrode on the side is made of a metal having a smaller ionization tendency than hydrogen, and the electrode on the high potential side need not be made of a metal having a smaller ionization tendency than hydrogen, for example, made of ITO. Also good.

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

  For example, in the said embodiment, although the 2nd electrode 40 was comprised as one electrode which is not isolate | separated, it is not restricted to this. The second electrode 40 may be constituted by a plurality of separated electrode pieces.

  Specifically, as shown in FIG. 4, the second electrode 40 </ b> A may be configured by a first electrode piece 41 and a second electrode piece 42 that are separated from each other. Thus, by applying different voltages to the first electrode 30, the first electrode piece 41, and the second electrode piece 42, the first electrode 30 and the second electrode 40 </ b> A (first electrode) in the refractive index variable layer 60. Not only an electric field distribution is formed between the electrode piece 41 and the second electrode piece 42), but also an electric field distribution is formed between the first electrode piece 41 and the second electrode piece 42. Thereby, the nanoparticles 62 are unevenly distributed according to the electric field distribution formed in the refractive index variable layer 60.

  As an example, by applying −20 V to the first electrode 30, applying +20 to the first electrode piece 41, and applying +15 to the second electrode piece 42, the gap between the first electrode 30 and the second electrode 40 </ b> A is obtained. In addition, an electric field distribution can be formed between the first electrode piece 41 and the second electrode piece 42.

  In this case, the light incident from the first substrate 10 is refracted twice in the refractive index variable layer 60 and then emitted from the second substrate 20. Accordingly, when the optical device shown in FIG. 4 is installed in the window, the light incident on the optical device 1 can be bent at a larger angle than the optical device 1 in the above-described embodiment, and the ceiling is closer to the window side. An optical device capable of light distribution toward the camera can be realized.

  Moreover, in the said embodiment, although the nanoparticle 62 was charged positively, it is not restricted to this. That is, the nanoparticles 62 may be negatively charged.

  In the above embodiment, in the second optical mode, a negative potential is applied to the first electrode 30 and a positive potential is applied to the second electrode 40. However, the present invention is not limited to this. For example, if a predetermined voltage (potential difference) is applied between the first electrode 30 and the second electrode 40, a positive potential is applied to both the first electrode 30 and the second electrode 40 in the second optical mode. Alternatively, a negative potential may be applied.

  Moreover, in the said embodiment, although the convex part 51 which comprises the uneven | corrugated structure 50 was an elongate square pillar with a cross-sectional shape trapezoid, it is not restricted to this. For example, the convex portion 51 may be a long triangular prism having a triangular cross section (for example, an isosceles triangle). Moreover, the cross-sectional shape of the side surface of the convex portion 51 is not limited to a straight line, and may be a curved line or a saw-like shape. Furthermore, each of the plurality of convex portions 51 is not limited to one long member extending in the X-axis direction, and may be partially divided in the X-axis direction.

  Moreover, in the said embodiment, although the height of the some convex part 51 was made constant, it is not restricted to this. For example, the heights of the plurality of convex portions 51 may be different at random. Or the space | interval of the convex part 51 may differ at random, and both height and a space | interval may be random.

  Moreover, in the said embodiment, although sunlight was illustrated as light which injects into the optical device 1, it does not restrict to this. For example, the light incident on the optical device 1 may be light emitted from a light emitting device such as a lighting fixture.

  Moreover, in the said embodiment, although the optical device 1 was arrange | positioned in the window so that the longitudinal direction of the convex part 51 may turn into an X-axis direction, it is not restricted to this. For example, the optical device 1 may be arranged in the window so that the longitudinal direction of the convex portion 51 is the Z-axis direction.

  Moreover, in the said embodiment, although the optical device 1 was affixed on the window, you may use the optical device 1 as the window itself of a building. The optical device 1 is not limited to being installed in a building window, and may be installed, for example, in a car window.

  In addition, any form obtained by making various modifications conceived by those skilled in the art to the above-described embodiment, or any combination of the components and functions in each of the above-described embodiments without departing from the gist of the present invention Embodiments realized by this are also included in the present invention.

DESCRIPTION OF SYMBOLS 1 Optical device 10 1st board | substrate 20 2nd board | substrate 30 1st electrode 40, 40A 2nd electrode 41 1st electrode piece 42 2nd electrode piece 50 Uneven structure 60 Refractive index variable layer 61 Insulating liquid 62 Nanoparticle

Claims (5)

A first substrate having optical transparency;
A second substrate having optical transparency disposed to face the first substrate;
A first electrode disposed on the second substrate side of the first substrate;
A concavo-convex structure disposed on the second substrate side of the first substrate;
A second electrode disposed on the first substrate side of the second substrate;
A refractive index variable layer that is disposed between the concavo-convex structure and the second electrode and has a refractive index that varies according to a voltage applied between the first electrode and the second electrode;
The refractive index variable layer has an insulating liquid and nanoparticles dispersed in the insulating liquid,
The refractive index of the nanoparticles is higher than the refractive index of the insulating liquid,
At least one of the first electrode and the second electrode is made of a metal having a smaller ionization tendency than hydrogen,
Optical device. Both the first electrode and the second electrode are made of a metal having a smaller ionization tendency than hydrogen,
The optical device according to claim 1. The first electrode and the second electrode are in contact with the insulating liquid,
The optical device according to claim 1 or 2. The metal is at least one selected from copper, silver, platinum and gold.
The optical device according to claim 1. The second electrode is composed of a plurality of electrode pieces.
The optical device according to claim 1.

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