JP2020064087A - Optical device - Google Patents

Abstract

To provide an optical device capable of reducing local glossiness and also properly transmitting light.SOLUTION: An optical device comprises: a first substrate 10 having light transmissivity; a second substrate 20 opposed to the first substrate 10 and having light transmissivity; a light distribution layer 30 arranged between the first substrate 10 and the second substrate 20, and distributing incident light; and a first electrode 40 and a second electrode 50 arranged with the light distribution layer 30 interposed. The light distribution layer 30 has: an uneven structure part 31 having a plurality of projection parts 32; and an optical medium part 34 arranged at a plurality of recessed parts 33 between the plurality of projection parts 32, and containing liquid crystal molecules 35, the optical medium part 34 varying in refractive index as a voltage is applied between the first electrode 40 and the second electrode 50. On the first substrate 10 side of the optical medium part 34 of the plurality of recessed parts 33, a light blocking part 60 is arranged which blocks at least part of the incident light and has a surface roughness equal to or less than a visible light wavelength on a contact surface 60 in contact with the optical medium part 34.SELECTED DRAWING: Figure 2

Description

  The present invention relates to optical devices.

  Conventionally, an optical device capable of changing a light transmission state is known. For example, Patent Document 1 discloses a liquid crystal optical element having a liquid crystal layer formed above a base having irregularities such as a prism layer. Patent Document 1 describes that, in this liquid crystal optical element, the alignment direction of liquid crystal molecules is aligned, so that, for example, a deflection operation for incident polarized light in a certain direction can be efficiently performed.

Japanese Unexamined Patent Publication No. 2015-041006

  However, in an optical device such as the above-mentioned conventional liquid crystal optical element, light scattering occurs at the apex and the apex of the uneven layer. For example, when a conventional optical device is used for a window of a building, when sunlight is incident on the optical device, light streaks are generated along the vertical (vertical) direction. For this reason, the person who is indoors feels locally dazzling when looking at the window, making it difficult to see the outside of the window and impairing the function as the window.

  The present invention has been made in consideration of the above-mentioned conventional problems, and an object thereof is to provide an optical device capable of reducing local glare and appropriately transmitting light.

  To achieve the above object, an optical device according to an aspect of the present invention includes a first substrate having a light-transmitting property, a second substrate facing the first substrate and having a light-transmitting property, and the first substrate. And a light distribution layer that is arranged between the second substrate and distributes incident light, and a first electrode and a second electrode that are arranged so as to sandwich the light distribution layer. A liquid crystal molecule, the concave-convex structure portion having a plurality of convex portions repeating along a first direction parallel to the main surface of the first substrate, and the liquid crystal molecules arranged in a plurality of concave portions between the convex portions. An optical medium part that changes its refractive index when a voltage is applied between the first electrode and the second electrode. On the side of the first substrate, which shields at least a part of the incident light and is in contact with the optical medium portion. Surface roughness of the contact surface light-shielding portion is disposed is below the visible light wavelength that.

  According to the optical device of the present invention, local glare can be reduced and light can be appropriately transmitted.

3 is a cross-sectional view of the optical device according to the first embodiment. FIG. 3 is a partial cross-sectional view of the optical device according to the first embodiment. FIG. 3 is an enlarged cross-sectional view of the optical device according to the first embodiment. FIG. 5 is an enlarged cross-sectional view for explaining a light distribution mode of the optical device according to the first embodiment. FIG. FIG. 3 is an enlarged cross-sectional view for explaining a translucent mode of the optical device according to the first embodiment. It is an expanded sectional view for explaining one cause of a streak of light generated in an optical device concerning a comparative example. It is a figure which shows the usage example at the time of installing the optical device (light distribution mode) which concerns on Embodiment 1 in a window. FIG. 6 is a partial cross-sectional view of the optical device according to the second embodiment. FIG. 6 is an enlarged cross-sectional view of the optical device according to the second embodiment.

  Hereinafter, optical devices according to embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that each of the embodiments described below shows a specific example of the present invention. Therefore, the numerical values, shapes, materials, constituent elements, arrangement and connection form of constituent elements, assembly order, and the like shown in the following embodiments are examples, and are not intended to limit the present invention. Therefore, among the constituent elements in the following embodiments, the constituent elements which are not described in the independent claims showing the highest concept of the present invention are described as arbitrary constituent elements.

  In addition, each drawing is a schematic view, and is not necessarily strictly illustrated. Therefore, for example, the scales and the like in the drawings do not necessarily match. In addition, in each of the drawings, substantially the same configurations are denoted by the same reference numerals, and overlapping description will be omitted or simplified.

  Further, in this specification and the drawings, the x-axis, the y-axis, and the z-axis represent the three axes of the three-dimensional orthogonal coordinate system. In each of the embodiments, 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. The positive direction of the z-axis is vertically upward. In addition, in the present specification, the “thickness direction” means the thickness direction of the optical device, is a direction perpendicular to the main surfaces of the first substrate and the second substrate, and the “plan view” is the It refers to when viewed from a direction perpendicular to the main surface of the first substrate or the second substrate.

(Embodiment 1)
[Constitution]
First, the configuration of the optical device 1 according to the first embodiment will be described with reference to FIGS. 1 to 3. FIG. 1 is a sectional view of the optical device 1 according to the first embodiment. FIG. 2 is a partial cross-sectional view of the optical device 1 according to the first embodiment. FIG. 3 is an enlarged cross-sectional view of the optical device 1 according to the first embodiment. Specifically, FIG. 2 is an enlarged cross-sectional view of a region II surrounded by the alternate long and short dash line of FIG. 1, and FIG. 3 is an enlarged cross-sectional view of a region III surrounded by the circular broken line of FIG.

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

  As shown in FIGS. 1 and 2, the optical device 1 is configured to transmit incident light, and includes a first substrate 10, a second substrate 20, a light distribution layer 30, and a first electrode 40. And a second electrode 50 and a light shielding portion 60.

  In addition, an adhesion layer may be provided on the surface of the first electrode 40 on the light distribution layer 30 side for bringing the first electrode 40 and the uneven structure portion 31 of the light distribution layer 30 into close contact with each other. The adhesion layer is, for example, a translucent adhesive sheet, a resin material generally called a primer, or the like.

  The optical device 1 has a configuration in which a first electrode 40, a light distribution layer 30, and a second electrode 50 are arranged in this order along a thickness direction between a pair of a first substrate 10 and a second substrate 20. . The light shielding portion 60 is provided in the concave portion 33 of the uneven structure portion 31 of the light distribution layer 30.

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

[First Substrate and Second Substrate]
The first substrate 10 and the second substrate 20 are translucent substrates 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 of the resin substrate include resin materials such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate (PC), acrylic (PMMA) or 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 that scattering at the time of breakage is small.

  The first substrate 10 and the second substrate 20 may be made of the same material, or may be made of different materials. The first substrate 10 and the second substrate 20 are not limited to rigid substrates, and may be flexible substrates having flexibility, for example. 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 arranged at a position facing the first substrate 10. The first substrate 10 and the second substrate 20 are adhered to each other by a seal resin such as an adhesive formed in a frame shape on the outer circumferences of their ends.

  The planar shape of the first substrate 10 and the second substrate 20 is, for example, a square or a rectangular shape in a plan view, but the shape is not limited to this and may be a polygon other than a circle or a quadrangle. That is, various shapes can be adopted as the planar view shapes of the first substrate 10 and the second substrate 20.

[Light distribution layer]
As shown in FIGS. 1 and 2, the light distribution layer 30 is disposed between the first substrate 10 and the second substrate 20. The light distribution layer 30 has a light-transmitting property and transmits incident light. Further, the light distribution layer 30 distributes the incident light. That is, the light distribution layer 30 can change the traveling direction of the light when the light passes through the light distribution layer 30.

  The light distribution layer 30 has an uneven structure portion 31 (uneven layer) and an optical medium portion 34 (optical medium layer) containing liquid crystal molecules 35.

  The concavo-convex structure portion 31 has a plurality of convex portions 32 and a plurality of concave portions 33. Specifically, the concavo-convex structure part 31 is a concavo-convex structure body composed of a plurality of convex parts 32 of micro-order size or nano-order size. A plurality of concave portions 33 are provided between the plurality of convex portions 32. That is, the space between two adjacent convex portions 32 is one concave portion 33.

  The plurality of protrusions 32 are repeatedly arranged along the z-axis direction (first direction) parallel to the main surface of the first substrate 10 (the surface on which the first electrode 40 is provided). Each of the plurality of protrusions 32 is a long protrusion extending in the x-axis direction (second direction). That is, in the present embodiment, the plurality of convex portions 32 are formed in a stripe shape in plan view.

  Specifically, each of the plurality of convex portions 32 has a trapezoidal sectional shape and extends in the x-axis direction. That is, each of the plurality of convex portions 32 has a long and substantially quadrangular prism shape, and is arranged at equal intervals along the z-axis direction. In the present embodiment, each of the plurality of convex portions 32 has the same shape, but may have different shapes.

  Each of the plurality of convex portions 32 has a pair of side surfaces 32a and 32b. As shown in FIG. 2, the pair of side surfaces 32a and 32b are surfaces that intersect in the z-axis direction. In the present embodiment, the cross-sectional shape of each of the plurality of convex portions 32 is a tapered shape that is tapered along the direction (thickness direction) from the first substrate 10 to the second substrate 20. Each of the pair of side surfaces 32a and 32b is an inclined surface that is inclined at a predetermined inclination angle with respect to the thickness direction, and the distance between the pair of side surfaces 32a and 32b (width of the convex portion 32 (length in the z-axis direction)). Is gradually reduced from the first substrate 10 toward the second substrate 20.

  The side surface 32a is, for example, a vertically upper side surface (upper side surface) of the pair of side surfaces 32a and 32b. The side surface 32b is, for example, a vertically lower side surface (lower side surface) of the pair of side surfaces 32a and 32b.

  As a material of the convex portion 32, a resin material having light transmittance such as acrylic resin, epoxy resin, or silicone resin can be used. The protrusion 32 can be formed by, for example, molding or nanoimprinting.

  In the present embodiment, the concavo-convex structure portion 31 is formed using, for example, acrylic resin having a refractive index of 1.5. The height of the protrusions 32 is, for example, 5 μm, and the plurality of protrusions 32 are arranged at equal intervals of 1 μm and arranged at equal intervals in the z-axis direction. The thickness of the root portion of the protrusion 32 (the lower base of the trapezoid) is, for example, 5 μm. The sectional shape of the convex portion 32 is not limited to the trapezoid, and may be a triangle, another polygon, a polygon including a curve, or the like.

  Further, the values of the height and the like of the convex portion 32 described above are examples, and the height (the length in the y-axis direction) of the convex portion 32 may be appropriately determined from the range of 100 nm to 100 μm, for example. Further, the interval between the adjacent convex portions 32, that is, the width of the concave portion 33 (z-axis direction) may be appropriately determined within a range of 0 to 100 μm, for example. That is, the two adjacent convex portions 32 may be arranged at a predetermined interval without contacting each other, or may be arranged in contact with each other.

  The optical medium unit 34 is, for example, a liquid crystal including liquid crystal molecules 35 having birefringence. As such a liquid crystal, for example, a nematic liquid crystal in which the liquid crystal molecules 35 are rod-shaped molecules, a smectic liquid crystal, a cholesteric liquid crystal, or the like can be used. The liquid crystal containing the liquid crystal molecules 35 is, for example, a positive liquid crystal having an ordinary light refractive index (no) of 1.5 and an extraordinary light refractive index (ne) of 1.7. That is, in the present embodiment, the optical medium unit 34 is a liquid crystal layer made of liquid crystal containing liquid crystal molecules 35.

  The optical medium section 34 is arranged in the plurality of recesses 33 of the concavo-convex structure section 31. Specifically, the optical medium portion 34 is arranged between the first electrode 40 and the second electrode 50 so as to fill the gap formed between the two adjacent convex portions 32. ing.

  In the present embodiment, the optical medium unit 34 functions as a refractive index adjusting layer whose refractive index in the visible light region can be adjusted by applying an electric field. Specifically, since the optical medium unit 34 is composed of liquid crystal having liquid crystal molecules 35 having electric field responsiveness, the alignment state of the liquid crystal molecules 35 changes when an electric field is applied to the light distribution layer 30, As a result, the refractive index of the optical medium unit 34 changes.

  An electric field is applied to the light distribution layer 30 by applying a voltage between the first electrode 40 and the second electrode 50. Therefore, by controlling the voltage applied to the first electrode 40 and the second electrode 50, the electric field applied to the light distribution layer 30 changes, which changes the alignment state of the liquid crystal molecules 35, and as a result, the optical medium. The refractive index of the portion 34 changes. That is, the refractive index of the optical medium unit 34 changes when a voltage is applied to the first electrode 40 and the second electrode 50.

  Note that FIG. 2 shows a state in which no voltage is applied (the same applies to FIG. 4A described later), and the liquid crystal molecules 35 are oriented so that their major axes are parallel to the x axis. When a voltage is applied between the first electrode 40 and the second electrode 50, the liquid crystal molecules 35 are aligned such that the major axis is parallel to the y axis (see FIG. 4B described later).

  The optical medium unit 34 may be supplied with an electric field by AC power or may be supplied with DC power. In the case of AC power, the voltage waveform may be a sine wave or a rectangular wave.

  The optical medium portion 34 is made of, for example, a seal resin on the outer periphery of each of the first substrate 10 on which the first electrode 40 and the uneven structure portion 31 are formed and the second substrate 20 on which the second electrode 50 is formed. It is formed by injecting a positive type liquid crystal containing liquid crystal molecules 35 in a sealed state by a vacuum injection method. Alternatively, the optical medium section 34 is formed by dropping the positive type liquid crystal containing the liquid crystal molecules 35 on the first electrode 40 and the concavo-convex structure section 31 of the first substrate 10 and then bonding the second substrate 20. .

[First electrode and second electrode]
In the present embodiment, the first electrode 40 and the second electrode 50 are electrically paired and are configured so that an electric field can be applied to the light distribution layer 30. The first electrode 40 and the second electrode 50 form a pair not only electrically but also in arrangement, and are arranged so as to face each other. Specifically, the first electrode 40 and the second electrode 50 are arranged so as to sandwich the light distribution layer 30.

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

  The first electrode 40 is arranged between the first substrate 10 and the light distribution layer 30. Specifically, the first electrode 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 50 is arranged between the light distribution layer 30 and the second substrate 20. Specifically, the second electrode 50 is formed on the surface of the second substrate 20 on the light distribution layer 30 side.

  The first electrode 40 and the second electrode 50 have a configuration capable of being electrically connected to an external power source, for example. For example, an electrode pad or the like for connecting to an external power source may be drawn from each of the first electrode 40 and the second electrode 50 and formed on the first substrate 10 and the second substrate 20.

[Shading part]
The light blocking unit 60 blocks at least part of the incident light. In the present specification, “shielding” means not only completely blocking incident light, but also blocking only part of the light and transmitting the rest. For example, “shading” refers to a state in which blocking is dominant rather than light transmission. Specifically, the transmittance of the light-shielding portion 60 with respect to visible light is lower than 50%, preferably 20% or less, or 10% or less.

  In the present embodiment, the light shield 60 is provided on the bottom of the recess 33. Specifically, the light shielding portion 60 is formed in a stripe shape extending in the x-axis direction, similarly to the concavo-convex structure portion 31. In the present embodiment, the light shields 60 are provided in all the recesses 33, but the present invention is not limited to this. For example, the light-shielding portions 60 may be provided at every n (n is a natural number of 1 or more) of the plurality of recesses 33 along the z-axis direction.

  In the present embodiment, the light shielding part 60 is formed with a substantially uniform film thickness. The film thickness (y-axis direction) of the light shielding unit 60 is, for example, 200 nm to 2 μm. The film thickness of the light shielding portion 60 can be appropriately determined, for example, in this range in consideration of the light absorption of the light shielding portion 60 or the height of the convex portion 32.

  As shown in FIG. 3, the light shielding unit 60 according to the present embodiment is formed of a plurality of light shielding particles 61 and a binder 62 that fixes the plurality of light shielding particles 61. As the light-shielding particles 61, for example, a carbon black pigment such as carbon black or an oxide black pigment is used. Further, as the binder 62, for example, acrylic resin is adopted.

  Specifically, a resin material containing a plurality of light-shielding particles 61 such as carbon black is applied to the plurality of recesses 33, and a heating (drying) process is performed, whereby the light-shielding portions 60 are respectively provided in the plurality of recesses 33. Are placed. In this way, after the light shielding portion 60 is arranged in each of the plurality of recesses 33, the above-mentioned optical medium portion 34 containing the liquid crystal molecules 35 is arranged on the light shielding portion 60. In addition, the light shielding unit 60 does not have to be black. For example, the light shielding unit 60 may be one obtained by drying a solvent ink containing a colored pigment. The drying may be natural drying.

  In the optical device 1 according to the present embodiment, the provision of the light shielding portion 60 makes it possible to suppress the generation of light streaks that has occurred in conventional optical devices. This will be described later with reference to FIGS. 4A, 4B and 5.

  Further, since the light-shielding portion 60 having the above effect is arranged in contact with the optical medium portion 34, the light-shielding portion 60 has a contact surface 60a (see FIG. 3) which is a surface in contact with the optical medium portion 34. ing. Further, the surface roughness of the contact surface 60a becomes large due to the influence of the plurality of light shielding particles 61 contained in the light shielding portion 60 if no measures are taken.

  When the surface roughness of the contact surface 60a is large, the inventors of the present invention have visible haze in the vicinity of the light-shielding portion 60, and when the surface roughness of the contact surface 60a is small, haze is suppressed. I was confirmed.

  Specifically, in the present embodiment, the surface roughness (for example, arithmetic mean roughness (Ra)) of contact surface 60a is equal to or less than the visible light wavelength. More specifically, the surface roughness of the contact surface 60a is 750 nm or less. Thereby, haze in the optical device 1 is suppressed. The surface roughness of the contact surface 60a is more preferably 350 nm or less, further preferably 100 nm or less.

  When the surface roughness of the contact surface 60a is large, the reason why the haze increases is, for example, when the surface roughness of the contact surface 60a is large, due to the uneven shape of the contact surface 60a, It is considered that poor alignment of the liquid crystal molecules 35 is likely to occur in the vicinity region. Therefore, the inventors of the present application suppress the occurrence of misalignment of the liquid crystal molecules 35 in the vicinity of the contact surface 60a by setting the surface roughness of the contact surface 60a to be equal to or less than the visible light wavelength, and as a result, there is a problem in appearance. It was found that such haze does not occur. In addition, the present inventors have confirmed that, in principle, the smaller the surface roughness of the contact surface 60a, the smaller the haze.

  Further, in order to form the contact surface 60a having a relatively small surface roughness, the present embodiment adopts a configuration in which the volume ratio of the binder 62 in the light shielding portion 60 is 30%. Specifically, in the light-shielding portion 60 having a thickness of, for example, about 1 μm, which is disposed in the recess 33, if a plurality of light-shielding particles 61 are densely arranged (sphere-filled), a plurality of light-shielding portions 60 have a plurality of volumes. The volume ratio of the light shielding particles 61 is about 70%. Therefore, in the present embodiment, the volume ratio of the binder 62 in the light shielding portion 60 is set to 30% or more. As a result, even if a plurality of light shielding particles 61 are spread in the volume allowed as the light shielding portion 60 in order to increase the light shielding degree of the light shielding portion 60, the surface roughness of the contact surface 60a has a visible light It is less than the wavelength.

  Here, for example, when the thickness of the light shielding portion 60 is maintained at a predetermined value (for example, 1 μm) and the volume ratio of the binder 62 is increased, the number of light shielding particles 61 contained in the light shielding portion 60 decreases. Thus, the light blocking degree of the light blocking section 60 decreases (the light transmittance of the light blocking section 60 increases). As a result, the effect of suppressing the light streaks may be reduced. However, on the other hand, since the surface roughness of the contact surface 60a of the light shielding portion 60 becomes small, the increase of the volume ratio of the binder 62 is advantageous from the viewpoint of suppressing the alignment failure of the liquid crystal molecules 35 (suppressing the haze). . Therefore, considering the balance between the effect of suppressing light streaks and the suppression of haze, the volume ratio of the binder 62 in the light shielding portion 60 is, for example, preferably 30% or more and 50% or less.

  Further, it is possible to increase the volume ratio of the binder 62 in the light shielding part 60 by increasing the volume of the light shielding part 60 while maintaining the number of the light shielding particles 61 contained in the light shielding part 60. In this case, the surface roughness of the contact surface 60a of the light shielding portion 60 becomes small, which is advantageous from the viewpoint of suppressing alignment failure of the liquid crystal molecules 35 (controlling haze).

  However, since the shape and size of the concave portion 33 are constant, in order to increase the volume of the light shielding portion 60, it is necessary to increase the thickness of the light shielding portion 60, and as a result, the density of the light shielding particles 61 decreases. Thus, the light blocking degree of the light blocking section 60 decreases (the light transmittance of the light blocking section 60 increases). This leads to a reduction in the light muscle suppression effect. Further, if the thickness of the light shielding portion 60 is increased, the thickness of the optical medium portion 34 in the concave portion 33 is reduced, so that the light distribution function, which is the original purpose of the optical device 1, may be reduced. In consideration of these circumstances, the thickness of the light shielding portion 60 is preferably, for example, 50% or less of the depth of the concave portion 33 (height of the convex portion 32).

  Note that an oxide film may be formed on the surface of the light-shielding portion 60 after the light-shielding portion 60 is arranged in each of the plurality of recesses 33 and before the optical medium portion 34 is arranged by a method such as a sputtering method. Good.

The oxide film (not shown) has a function of preventing the light shielding unit 60 from mixing with the optical medium unit 34 (liquid crystal). The oxide film is, for example, a silicon oxide film (SiO ₂ ). When a layer such as an oxide film is formed on the surface of the light shielding portion 60, the surface of the layer on the optical medium portion 34 side is the surface (contact surface) in contact with the optical medium portion 34 of the light shielding portion 60. It can also be interpreted. In this case, the surface roughness of the surface of the layer on the optical medium portion 34 side may be equal to or less than the visible light wavelength.

[Optical state of optical device]
Next, the optical state of the optical device 1 according to the first embodiment will be described with reference to FIGS. 4A and 4B. The optical device 1 has two optical states (operation modes) according to the applied state of the electric field to the light distribution layer 30. Specifically, the optical device 1 has a light distribution mode that changes the traveling direction of incident light and a translucent mode that allows incident light to pass as it is (without changing the traveling direction).

  FIG. 4A is an enlarged cross-sectional view for explaining the light distribution mode of the optical device 1 according to the first embodiment. FIG. 4B is an enlarged cross-sectional view for explaining the translucent mode of the optical device 1 according to the first embodiment.

  In the optical device 1, liquid crystal molecules included in the optical medium unit 34 according to an electric field applied to the light distribution layer 30, specifically, a voltage applied between the first electrode 40 and the second electrode 50. The orientation of 35 changes. Since the liquid crystal molecule 35 is a rod-shaped liquid crystal molecule having birefringence, the refractive index varies depending on the polarization state of incident light.

  Light such as sunlight that enters the optical device 1 includes P-polarized light (P-polarized light component) and S-polarized light (S-polarized light component). The vibration direction of P-polarized light is substantially parallel to the minor axis of the liquid crystal molecules 35 in both modes of FIG. 4A and FIG. 4B. Therefore, the refractive index of the liquid crystal molecules 35 for P-polarized light does not depend on the mode and is the ordinary light refractive index (no), specifically, 1.5. Therefore, the refractive index for P-polarized light is substantially constant in the light distribution layer 30, and the P-polarized light travels straight in the light distribution layer 30.

  The refractive index of the liquid crystal molecules 35 for S-polarized light changes according to the modes of FIGS. 4A and 4B. The details of each mode will be described below. In the present specification, unless otherwise specified, S-polarized light of light incident on the optical device 1 will be mainly described.

  As shown in FIG. 4A, when the optical device 1 is in the light distribution mode, a difference in refractive index occurs between the convex portion 32 and the optical medium portion 34 (concave portion 33). In this embodiment, the convex portion 32 has a refractive index of 1.5, and the optical medium portion 34 has a refractive index of 1.7.

[Light incident on the optical device at an angle]
Of the light such as sunlight that obliquely enters the optical device 1, the light L1 that does not enter the light shielding unit 60 is, as illustrated in FIG. 4A, the side surface 32b when entering the optical medium unit 34 from the convex portion 32. After being refracted by, the light is reflected by the side surface 32a when entering the convex portion 32 from the optical medium portion 34, and advances obliquely upward. Note that the P-polarized light passes through the optical device 1 as it is and advances obliquely downward without being refracted by the side surface 32b and reflected by the side surface 32a.

  On the other hand, as shown in FIG. 4B, when the optical device 1 is in the translucent mode, there is no difference in the refractive index in the light distribution layer 30, so that the light L1 (both P-polarized light and S-polarized light) is It passes through the optical device 1 as it is and advances obliquely downward.

[Light incident on the optical device substantially vertically]
Of the light that enters the optical device 1 substantially vertically, the light L2 that does not enter the light shielding portion 60 passes through the convex portion 32 as it is, as shown in FIGS. 4A and 4B. The light L2 passes straight through the optical device 1 in both the light distribution mode and the light transmission mode.

  In the light distribution mode, of the light L2 that does not enter the light shielding unit 60, the light (S-polarized light, not shown) that passes through the side surface 32a or 32b is refracted by the side surface 32a or 32b. At this time, since the light is shallowly incident on the side surface 32a or 32b (the incident angle is large), these lights are refracted at the side surface 32a or 32b and then as they are (without being reflected by another side surface). Emitted from 20. The P-polarized light passes through the optical device 1 as it is.

[Function of light-shielding part]
Next, the function of the light shielding unit 60 of the optical device 1 will be described with reference to FIG. 5 in addition to FIGS. 4A and 4B. FIG. 5 is an enlarged cross-sectional view for explaining one factor of a streak of light generated in the optical device 1x according to the comparative example. The optical device 1x shown in FIG. 5 is different from the optical device 1 according to the first embodiment (see, for example, FIG. 2) in that the light shielding unit 60 is not provided. Note that FIG. 5 shows the case where the optical device 1x is in the light distribution mode. Specifically, the refractive index of the optical medium portion 34 of the light distribution layer 30 is higher than the refractive index of the convex portion 32.

  At this time, the light L1 entering the optical medium portion 34 (recess 33) from the first electrode 40 is partially scattered due to the difference in the refractive index between the first electrode 40 and the optical medium portion 34 (FIG. 5). Scattered light Lx). Most of the scattered light is light that travels in the yz plane and therefore appears as light streaks along the z-axis direction. As a result, a person who looks at the optical device 1 from the front feels a line-shaped local glare.

  On the other hand, in the optical device 1 according to the present embodiment, as shown in FIGS. 1 to 4B, the light shielding portion 60 is provided in the concave portion 33 of the concavo-convex structure portion 31.

  As shown in FIGS. 4A and 4B, of the light obliquely incident on the optical device 1, the light L3 incident on the light shielding unit 60 is shielded by the light shielding unit 60. As a result, the generation of the scattered light Lx as shown in FIG. 5 is suppressed. Since the intensity of each of the scattered lights Lx is weaker than the main component of the light L1, it is sufficiently attenuated by the light shielding unit 60. Of the light that enters the optical device 1 substantially perpendicularly, the light L4 that enters the light blocking unit 60 is also blocked by the light blocking unit 60. In both the light distribution mode and the light transmission mode, the light beams L3 and L4 are blocked by the light blocking unit 60.

  In the present embodiment, since the width of the light shielding portion 60 (z-axis direction) is smaller than the width of the root portion of the convex portion 32 (z-axis direction), the light amounts of the light L3 and L4 shielded by the light shielding portion 60 are equal to each other. , Less than the light amount of the lights L1 and L2 passing through the convex portion 32. Therefore, the optical device 1 can transmit most (for example, 80%) or more of the light incident on the optical device 1.

  Note that, as described above, the light shielding unit 60 may transmit a part of the lights L3 and L4. In this case, the transmitted light of the light L3 is reflected by the side surface 32a of the convex portion 32 and is emitted from the second substrate 20 obliquely upward as in the case of the light L1. Further, the transmitted light of the light L4 is directly transmitted through the optical device 1 as it is, like the light L2.

  In the vicinity of the contact surface 60a (see FIG. 3) of the light shielding unit 60, for example, light that is repeatedly reflected in the optical medium unit 34 and light that is incident from the first substrate 10 and transmitted through the light shielding unit 60. Arrives and the light is affected by refraction by the liquid crystal molecules 35 near the contact surface 60a. With respect to this point, in the present embodiment, as described above, the surface roughness of the contact surface 60a is small (is equal to or less than the visible light wavelength), and thus alignment failure of the liquid crystal molecules 35 is unlikely to occur. Therefore, haze caused by poor alignment of the liquid crystal molecules 35 is suppressed.

[Example of use]
Here, a usage example of the optical device 1 according to the present embodiment will be described with reference to FIG. FIG. 6 is a diagram showing a usage example when the optical device 1 (light distribution mode) according to the present embodiment is installed in a window.

  As shown in FIG. 6, the optical device 1 can be realized as a window with a light distribution function by installing it in the window 91 of the building 90. The optical device 1 is attached to the existing window 91 via an adhesive layer, for example. In this case, the optical device 1 is installed in the window 91 such that the principal surfaces of the first substrate 10 and the second substrate 20 are parallel to the vertical direction (z-axis direction).

  Although the detailed structure of the optical device 1 is not shown in FIG. 6, in the optical device 1, the first substrate 10 is the outdoor side and the second substrate 20 is the indoor side, and the side surface of the convex portion 32 is the same. 32a is arranged so that the side surface 32b is on the ceiling side and the side surface 32b is on the floor side. That is, the optical device 1 is arranged such that the first substrate 10 is on the light incident side and the second substrate 20 is on the light emitting side.

  When the optical device 1 is in the light distribution mode, a difference in refractive index occurs between the convex portion 32 and the optical medium portion 34, so that the light L1 (S polarized light) is reflected by the side surface 32a as shown in FIG. 4A. Then, the vehicle moves diagonally upward. Therefore, as shown in FIG. 6, the indoor ceiling is illuminated by the light reflected by the side surface 32a. In this way, by taking in sunlight and irradiating the ceiling surface, it is possible to make the interior bright. Thereby, for example, the indoor lighting device can be turned off or the light output can be suppressed, so that power saving can be achieved.

  At this time, of the reflected light from the scenery (light incident on the optical device 1 substantially perpendicularly), the light that does not pass through the side surface 32a or 32b does not change its traveling direction, so the scenery can be seen by the light. . Further, the light passing through the side surface 32a or 32b changes the traveling direction of S-polarized light, but does not change the traveling direction of P-polarized light.

  Therefore, even in the light distribution mode, the transmittance of reflected light from the scenery can be set to 50% or more. Therefore, it is possible to lighten the interior while maintaining the open feeling due to the original transparency of the window.

  Further, in the optical device 1, the light shielding portion 60 can suppress scattered light. As a result, it is possible to suppress the local glare that appears as light streaks.

  Further, in the optical device 1, the haze is also suppressed by the surface roughness of the contact surface 60a (see FIG. 3) in the light shielding portion 60 including the plurality of light shielding particles 61 being small (not more than the visible light wavelength).

  Further, in the optical device 1, the traveling direction of the light L1 reflected by the side surface 32a can be controlled by the refractive index of the optical medium portion 34. That is, the elevation angle of the light emitted from the optical device 1 can be adjusted. Specifically, the elevation angle of the emitted light can be adjusted by adjusting the refractive index of the optical medium unit 34. The refractive index of the optical medium unit 34 can be adjusted stepwise by controlling the voltage applied between the first electrode 40 and the second electrode 50.

  For example, since the sun altitude changes depending on the season or time, the incident angle of sunlight incident on the optical device 1 changes depending on the season or time. On the other hand, in the optical device 1, the emission angle (elevation angle) of the light emitted from the optical device 1 can be made substantially constant by adjusting the refractive index of the optical medium section 34. Thereby, even when the sun altitude is different depending on the season or time, it is possible to irradiate a fixed area on the ceiling surface at all times. Therefore, regardless of the season or the time, it is possible to improve the lighting efficiency and save power.

[Effect]
As described above, the optical device 1 according to the present embodiment includes the first substrate 10 having a light-transmitting property, the second substrate 20 facing the first substrate 10 and having a light-transmitting property, and the first substrate 10. Further, the light distribution layer 30 arranged between the second substrate 20 and the incident light is provided, and the first electrode 40 and the second electrode 50 arranged so as to sandwich the light distribution layer 30. The light distribution layer 30 is between the convexo-concave portion 31 and the concave-convex structure portion 31 having a plurality of convex portions 32 that repeat along a first direction (z-axis direction) parallel to the main surface of the first substrate 10. An optical medium part 34 containing liquid crystal molecules 35 arranged in a plurality of recesses 33, the refractive index of which changes when a voltage is applied between the first electrode 40 and the second electrode 50. 34 and. On the first substrate 10 side of the optical medium portion 34 in the plurality of recesses 33, at least a part of the incident light is shielded, and the surface roughness of the contact surface 60 a that is in contact with the optical medium portion 34 has a surface roughness. A light shielding portion 60 having a wavelength of visible light or less is arranged.

  According to this configuration, since the light blocking portion 60 is provided in the recess 33, the light blocking portion 60 can block the scattered light generated in the recess 33. Therefore, it is possible to suppress the generation of the streak of light as described in FIG. 5, and it is possible to reduce the local glare. Further, when a voltage is applied between the first electrode 40 and the second electrode 50, the refractive index of the optical medium unit 34 can be changed, so that the optical device 1 has a plurality of optical states depending on the applied voltage. Can be realized. For example, the optical device 1 can realize a light distribution mode in which incident sunlight or the like advances toward an indoor ceiling surface and a translucent mode in which incident sunlight or the like advances as it is.

  Here, the light shielding portion 60 includes, for example, a plurality of light shielding particles 61, but the roughness of the contact surface 60a that contacts the optical medium portion 34 (liquid crystal) is not more than the visible light wavelength. As a result, defective alignment of the liquid crystal molecules 35 near the contact surface 60a is suppressed, and as a result, haze is also suppressed.

  As described above, according to the present embodiment, it is possible to provide the optical device 1 capable of reducing local glare and capable of appropriately transmitting light.

  In addition, in the present embodiment, the light shielding portion 60 is formed of a plurality of light shielding particles 61 and a binder 62 that fixes the plurality of light shielding particles 61, and the volume ratio of the binder 62 in the light shielding portion 60 is 30% or more. Is.

  According to this configuration, for example, the contact surface 60a having a surface roughness equal to or less than the visible light wavelength can be formed in the light shielding part 60 by a simple method of adjusting the volume ratio of the binder 62 in the light shielding part 60. it can.

  Further, in the present embodiment, specifically, the surface roughness of the contact surface 60a of the light shielding unit 60 is 750 nm or less. The surface roughness of the contact surface 60a is more preferably 350 nm or less, further preferably 100 nm or less.

  Thus, by forming the contact surface 60a having a surface roughness equal to or less than the reference, for example, 750 nm, which is the upper limit of the visible light wavelength, the haze can be effectively suppressed.

(Embodiment 2)
Next, the second embodiment will be described focusing on the differences from the first embodiment. That is, in the following description, the common points with the first embodiment may be omitted or simplified.

  FIG. 7 is a partial cross-sectional view of the optical device 1a according to the second embodiment. FIG. 8 is an enlarged cross-sectional view of the optical device 1a according to the second embodiment. Specifically, FIG. 8 is an enlarged cross-sectional view of a region VIII surrounded by the elliptical broken line in FIG. 7.

  As shown in FIG. 7, in the optical device 1a according to the present embodiment, as compared with the optical device 1 according to the first embodiment shown in FIG. Different from part 60.

  Specifically, the light shielding unit 65 according to the present embodiment is disposed between the light shielding layer 66 that shields at least a part of the incident light and the light shielding layer 66 and the optical medium unit 34, and the optical medium unit 34. And a planarization layer 67 that forms a contact surface 65a that contacts.

  In the present embodiment, the light-shielding layer 66 is formed by a plurality of light-shielding particles 61 and a binder 62 that fixes the plurality of light-shielding particles 61, like the light-shielding portion 60 according to the first embodiment. Therefore, the effect of locally reducing the glare due to the presence of the light shielding layer 66 in the recess 33 is achieved.

  Here, in the present embodiment, the boundary between the light-shielding layer 66 and the planarization layer 67 is affected by the plurality of light-shielding particles 61 contained in the light-shielding layer 66, so that relatively large irregularities are formed in the y-axis direction. Has been formed. However, the flattening layer 67 that absorbs the irregularities of the light shielding layer 66 is disposed between the light shielding layer 66 and the optical medium unit 34, and the surface roughness of the contact surface 65a is the same as that in the first embodiment. Like the contact surface 60a, the wavelength is less than or equal to the visible light wavelength. Therefore, alignment failure of the liquid crystal molecules 35 near the contact surface 65a is suppressed, and as a result, haze is also suppressed.

  Further, in the present embodiment, since it is not necessary to reduce the surface roughness of the surface of the light shielding layer 66 (contact surface with the flattening layer 67), for example, the amount of the binder 62 is fixed to the plurality of light shielding particles 61. It can be suppressed to the minimum necessary amount. Further, since the flattening layer 67 forming the contact surface 65a does not need to contain solids such as the light-shielding particles 61, which is one of the factors for roughening the surface, the surface roughness of the contact surface 65a is, for example, 750 nm. It is easy to do the following:

  As described above, according to the present embodiment, it is possible to provide the optical device 1a that can reduce local glare and can appropriately transmit light.

  As the material of the flattening layer 67, for example, a resin material diluted with water is adopted. In this case, for example, it is difficult to adhere to the water-repellent resin (acrylic resin or the like) that forms the uneven structure portion 31. Therefore, when the resin material is applied from above the light shielding layer 66 accommodated in the recess 33, the flattening layer 67 can be formed only on the light shielding layer 66. An acrylic resin is exemplified as such a resin material.

  Further, for example, a resin material having a high affinity with the light shielding particles 61 such as carbon black contained in the light shielding layer 66 can be arbitrarily selected and used as the material of the flattening layer 67. This facilitates the formation of the flattening layer 67 on the light shielding layer 66, for example.

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

  For example, in the above-described first embodiment, an example in which the light shielding unit 60 may partially transmit light has been described, but the light shielding unit 60 may completely block light. Further, at this time, the light shielding unit 60 may absorb or reflect the light.

  Further, for example, in the above-described first embodiment, the optical device 1 is arranged in the window such that the longitudinal direction of the convex portion 32 is the x-axis direction, but the present invention is not limited to this. For example, the optical device 1 may be arranged in the window such that the longitudinal direction of the convex portion 32 is the z-axis direction.

  Further, for example, in the above-described first embodiment, each of the plurality of convex portions 32 configuring the concave-convex structure portion 31 has a long shape, but the present invention is not limited to this. For example, the plurality of convex portions 32 may be arranged so as to be scattered in a matrix or the like. That is, you may arrange | position the some convex part 32 so that it may be dotted and scattered.

  Further, for example, in the first embodiment described above, each of the plurality of convex portions 32 has the same shape, but the present invention is not limited to this, and may have different shapes in the plane, for example. For example, the inclination angles of the side surfaces 32a of the plurality of convex portions 32 may be different between the upper half and the lower half of the optical device 1 in the z-axis direction.

  Further, for example, in the above-described first embodiment, the height of the plurality of convex portions 32 is constant, but the height is not limited to this. For example, the heights of the plurality of convex portions 32 may be randomly different. By doing so, it is possible to prevent the light passing through the optical device 1 from appearing in a rainbow color. That is, by randomly varying the heights of the plurality of convex portions 32, the minute diffracted light and scattered light at the concave-convex interface are averaged by the wavelength and the coloring of the emitted light is suppressed.

  Further, in the above-described first embodiment, sunlight is illustrated as the light incident on the optical device 1, but the light is not limited to this. For example, the light incident on the optical device 1 may be light emitted by a light emitting device such as a lighting device.

  Further, although the optical device 1 is attached to the indoor side surface of the window 91 in the first embodiment, it may be attached to the outdoor side surface of the window 91. By sticking it on the indoor side, deterioration of the optical element can be suppressed. Further, although the optical device 1 is attached to the window, the optical device may be used as the window itself of the building 90. The optical device 1 is not limited to being installed in the window 91 of the building 90, and may be installed in, for example, a car window.

  It should be noted that these modified examples can also be applied to other embodiments and modified examples. In addition, it is realized by making various modifications to those skilled in the art by those skilled in the art, and by arbitrarily combining the components and functions of each embodiment without departing from the spirit of the present invention. The form is also included in the present invention.

1, 1a Optical device 10 First substrate 20 Second substrate 30 Light distribution layer 31 Concavo-convex structure part 32 Convex part 33 Recessed part 34 Optical medium part 35 Liquid crystal molecule 40 First electrode 50 Second electrode 60, 65 Light shielding part 60a, 65a Contact Surface 61 Light-shielding particles 62 Binder 66 Light-shielding layer 67 Flattening layer

Claims (4)

A first substrate having translucency,
A second substrate facing the first substrate and having a light-transmitting property;
A light distribution layer that is arranged between the first substrate and the second substrate and distributes incident light;
A first electrode and a second electrode arranged so as to sandwich the light distribution layer,
The light distribution layer is
A concavo-convex structure part having a plurality of convex parts that repeat along a first direction parallel to the main surface of the first substrate;
An optical medium portion containing liquid crystal molecules, which is disposed in a plurality of concave portions between the plurality of convex portions, and has a refractive index when a voltage is applied between the first electrode and the second electrode. Has an optical medium portion that changes,
On the first substrate side of the optical medium portion in the plurality of concave portions, at least a part of incident light is shielded, and the surface roughness of a contact surface which is a surface in contact with the optical medium portion is visible. An optical device in which a light-shielding part having a light wavelength or less is arranged. The light-shielding portion is formed of a plurality of light-shielding particles and a binder that fixes the plurality of light-shielding particles,
The optical device according to claim 1, wherein a volume ratio of the binder in the light shielding portion is 30% or more. The light blocking portion is a light blocking layer that blocks at least a part of incident light,
The optical device according to claim 1, further comprising: a flattening layer that is disposed between the light shielding layer and the optical medium portion and that forms the contact surface. The surface roughness of the said contact surface of the said light shielding part is 750 nm or less, The optical device of any one of Claims 1-3.

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