Optical laminate and illumination device

Abstract

An optical laminate (100A) has a first primary surface and a second primary surface on the side opposite from the first primary surface. The optical laminate (100A) includes: a light guide layer (10) having a light receiving portion (10a) that receives light emitted from a light source (LS), a third primary surface (10b) which is on the first primary surface side, and a fourth primary surface (10c) which is on the second primary surface side; a mirror layer (1) that is light reflective and disposed on the fourth primary surface (10c) side of the light guide layer (10); and a light distribution control structure having a plurality of internal spaces (IS), wherein the plurality of internal spaces (IS) form an interface that directs a portion of the light propagating through the inside of the light guide layer (10) toward the first primary surface side or the second primary surface side by internal total reflection.

Description

Optical laminate and lighting device

[0001] The present invention relates to an optical laminate and a lighting device.

[0002] Mirrors with lighting devices that are equipped with lighting devices to illuminate the user are known for the purpose of improving convenience when using a mirror. Mirrors with lighting devices are disclosed, for example, in Patent Documents 1 and 2.

[0003] In the mirror with an illumination device disclosed in Patent Document 1, light is emitted diagonally upward and forward from a light source located on the back side of the mirror, and is reflected diagonally downward and forward by a reflector located above the mirror, thereby providing illumination.In the mirror with an illumination device disclosed in Patent Document 2, a ring-shaped light-transmitting portion is provided on the outer periphery of the mirror, and light emitted from an LED light source located on the back side of the mirror is emitted from the light-transmitting portion to the front side, thereby providing illumination.

[0004] JP 2019-139995 A JP 2019-154994 A

[0005] In conventional mirrors with lighting devices such as those disclosed in Patent Documents 1 and 2, the lighting devices attached to the mirror are solely for the purpose of illuminating the user of the mirror.

[0006] An object of an embodiment of the present invention is to provide a lighting device that is rich in design or entertainment value, and an optical laminate that is suitable for use in such a lighting device.

[0007] According to an embodiment of the present invention, the following solutions are provided:

[0008] [Item 1] An optical laminate having a first main surface and a second main surface opposite to the first main surface, comprising: a light receiving section that receives light emitted from a light source; a light guide layer having a third main surface on the first main surface side and a fourth main surface on the second main surface side; a mirror layer having light reflectivity and arranged on the fourth main surface side of the light guide layer; and a light distribution control structure having a plurality of internal spaces, the plurality of internal spaces forming interfaces that direct a portion of light propagating within the light guide layer toward the first main surface side or the second main surface side by total internal reflection.

[0009] [Item 2] The optical laminate according to item 1, further comprising a polarized light selective reflection layer disposed on the first main surface side with respect to the light distribution control structure.

[0010] [Item 3] The optical laminate according to Item 2, further comprising a quarter-wave plate disposed between the polarized-light selective reflection layer and the mirror layer.

[0011] [Item 4] The optical laminate according to any one of Items 1 to 3, further comprising an antireflection layer disposed on the first main surface side of the light distribution control structure.

[0012] [Item 5] The optical laminate according to any one of Items 1 to 4, further comprising a water-repellent and / or oil-repellent antifouling layer as the outermost layer on the first main surface side.

[0013] [Item 6] The optical laminate according to any one of Items 1 to 5, wherein the light distribution control structure includes a first light distribution control structure in which the plurality of internal spaces are formed in the light guide layer.

[0014] [Item 7] The optical laminate according to any one of Items 1 to 5, wherein the light distribution control structure includes a second light distribution control structure in which the plurality of internal spaces are formed in a direction changing layer provided on the third main surface side or the fourth main surface side of the light guide layer.

[0015] [Item 8] The optical laminate according to item 7, further comprising an optical coupling layer provided between the light guide layer and the direction conversion layer, wherein the optical coupling layer has a plurality of low refractive index regions having a refractive index lower than that of the light guide layer.

[0016] [Item 9] The optical laminate according to any one of Items 1 to 8, wherein, when viewed in a plan view from a normal direction to the first main surface, a first region in which the light distribution control structure is present and a second region in which the light distribution control structure is not present are arranged so as to define a predetermined pattern.

[0017] [Item 10] When viewed in a planar view from a normal direction to the first main surface, a first region in which the optical coupling layer is present and a second region in which the optical coupling layer is not present are arranged to define a predetermined pattern. The optical laminate according to item 8.

[0018] [Item 11] An illumination device comprising: the optical laminate according to any one of items 1 to 10; and a light source that emits light toward the light receiving section.

[0019] According to the embodiments of the present invention, it is possible to provide a lighting device that is rich in design or entertainment value, and an optical laminate that is suitable for use in such a lighting device.

[0020] 1 is a cross-sectional view schematically showing a lighting device 100A_L according to an embodiment of the present invention. FIG. 2 is a plan view schematically showing the lighting device 100A_L. FIG. 3 is a cross-sectional view schematically showing an internal space IS of the light distribution control structure of the lighting device 100A_L. FIG. 4 is a plan view schematically showing the internal space IS. FIG. 5 is a cross-sectional view schematically showing the lighting device 100A_L. FIG. 6 is a cross-sectional view schematically showing another lighting device 100B_L according to an embodiment of the present invention. FIG. 7 is a cross-sectional view schematically showing yet another lighting device 100C_L according to an embodiment of the present invention. FIG. 8 is a cross-sectional view schematically showing yet another lighting device 100D_L according to an embodiment of the present invention. FIG. 9 is a cross-sectional view schematically showing the lighting device 100D_L. FIG. 10 is a cross-sectional view schematically showing yet another lighting device 100E_L according to an embodiment of the present invention. FIG. 11 is a cross-sectional view schematically showing the lighting device 100E_L. FIG. 12 is a cross-sectional view schematically showing the lighting device 100E_L. FIG. 13 is a cross-sectional view schematically showing yet another lighting device 100F_L according to an embodiment of the present invention. FIG. 1 is a cross-sectional view schematically showing an illumination device 100F_L. FIG. 2 is a cross-sectional view schematically showing an illumination device 100A_L. FIG. 3 is a cross-sectional view schematically showing an illumination device 100E_L. FIG. 4 is a cross-sectional view schematically showing yet another illumination device 100G_L according to an embodiment of the present invention. FIG. 5 is a cross-sectional view schematically showing an illumination device 100G_L. FIG. 6 is a cross-sectional view schematically showing yet another illumination device 100H_L according to an embodiment of the present invention. FIG. 7 is a plan view showing an example of the arrangement of first regions R1 and second regions R2 of illumination device 100H_L. FIG. 8 is a cross-sectional view schematically showing yet another illumination device 100I_L according to an embodiment of the present invention.

[0021] Hereinafter, an optical laminate and a lighting device according to an embodiment of the present invention will be described with reference to the drawings. Note that the optical laminate and the lighting device according to the embodiment of the present invention are not limited to those exemplified in the following description.

[0022] [Configuration of Optical Stack and Illumination Device] Illumination device 100A_L according to an embodiment of the present invention will be described with reference to Fig. 1. Fig. 1 is a cross-sectional view that schematically shows illumination device 100A_L.

[0023] 1, the lighting device 100A_L includes a light source LS and an optical laminate 100A. As will be described later, the lighting device 100A_L functions to illuminate the area ahead when the light source LS is turned on, and also functions as a mirror when the light source LS is turned off.

[0024] The light source LS is, for example, an LED device. A plurality of LED devices may be used as the light source LS. The plurality of LED devices may be arranged in the X direction, for example.

[0025] The optical laminate 100A has a first main surface and a second main surface opposite the first main surface. In Fig. 1 , the upper main surface is the first main surface, and the lower main surface is the second main surface. When the lighting device 100A_L functions as a mirror, the first main surface is located on the viewer side (front side), and the second main surface is located on the opposite side from the viewer side (rear side).

[0026] The optical stacked body 100A receives light emitted from the light source LS, propagates the light in the Y direction, and emits the light in the Z direction. Therefore, the first main surface of the optical stacked body 100A functions as a light emitting surface. Of course, the propagation direction of the light has variation (distribution) from the Y direction, and the emission direction of the light also has variation (distribution) from the Z direction. Note that a coupling optical system may be provided between the optical stacked body 100A and the light source LS to efficiently guide the light emitted from the light source LS to the optical stacked body 100A.

[0027] The optical laminate 100A includes a light guide layer 10 and a mirror layer 1 .

[0028] The light guide layer 10 has a light receiving portion that receives light emitted from the light source LS, a third main surface 10b located on the first main surface side (i.e., the light emitting surface side), and a fourth main surface 10c located on the second main surface side (i.e., the side opposite the light emitting surface side). In the example shown, the light receiving portion of the light guide layer 10 is the side surface (light receiving side surface) 10a of the light guide layer 10 on the light source LS side. In addition, in the example shown, the light guide layer 10 is located on the outermost surface on the first main surface side of the optical stacked body 100A, and therefore the third main surface 10b of the light guide layer 10 is the first main surface of the optical stacked body 100A.

[0029] The mirror layer 1 is disposed on the fourth major surface 10c side of the light guide layer 10. The mirror layer 1 has light reflectivity. As will be described later, the mirror layer 1 includes a layer formed from a material that specularly reflects light.

[0030] The optical laminate 100A further includes a light distribution control structure having a plurality of internal spaces IS. The plurality of internal spaces IS included in the light distribution control structure form interfaces that direct a portion of the light propagating through the light guide layer 10 toward the first principal surface by total internal reflection (TIR). Each internal space IS has a first inclined surface ISa that directs a portion of the light propagating through the light guide layer 10 toward the first principal surface by total internal reflection, and a second inclined surface ISb opposite to the first inclined surface ISa.

[0031] In the illustrated optical laminate 100A, the light distribution control structure having a plurality of internal spaces IS is formed in the light guide layer 10. In this specification, the light distribution control structure formed in the light guide layer 10 may be referred to as the "first light distribution control structure."

[0032] The luminous intensity distribution of the light emitted from the first main surface of the optical laminate 100A can be controlled by adjusting the cross-sectional shape, size, arrangement density, and distribution of the internal space IS. The internal space IS is typically an air cavity filled with air.

[0033] Furthermore, the visible light transmittance and haze value of the light guide layer 10 can be controlled by adjusting the cross-sectional shape, size, arrangement density, and distribution of the internal space IS. The visible light transmittance of the light guide layer 10 is, for example, 60% or more, and preferably 80% or more. The haze value of the light guide layer 10 is, for example, less than 30%, and preferably less than 10%. Here, visible light is defined as light having a wavelength of 380 nm or more and 780 nm or less. The visible light transmittance and haze value can be measured, for example, using a haze meter (manufactured by Murakami Color Research Laboratory: product name HM-150).

[0034] When the optical laminate 100A is viewed in a plan view from the normal direction of the first main surface, the ratio of the area of ​​the plurality of internal spaces IS to the area of ​​the light guide layer 10 (occupancy rate) is preferably 1% or more and 80% or less, and more preferably 1% or more and 50% or less. From the viewpoint of obtaining a low haze value, the occupation rate of the internal spaces IS is preferably 30% or less, and more preferably 10% or less.

[0035] Examples of the shape and arrangement of the internal space IS will be described with reference to Figures 2, 3, and 4. Figure 2 is a plan view schematically showing the lighting device 100A_L. Figure 3 is a cross-sectional view schematically showing the internal space IS, and Figure 4 is a plan view schematically showing the internal space IS.

[0036] As shown in FIG. 2 , the multiple internal spaces IS may be discretely arranged in, for example, the light guide direction (Y direction) of the light guide layer 10 and a direction intersecting the light guide direction. The discrete arrangement may have periodicity (regularity) in at least one direction, or may not have regularity. However, from the viewpoint of mass productivity, it is preferable that the multiple internal spaces IS be uniformly arranged. For example, in the example shown in FIG. 2 , multiple internal spaces IS having substantially the same shape and convex curved surfaces in the same direction are discretely and periodically arranged in the light guide direction (Y direction) of the light guide plate 10 and a direction perpendicular to the light guide direction (X direction). In this case, the pitch Px of the internal spaces IS in the X direction is preferably, for example, 10 μm or more and 500 μm or less, and the pitch Py of the internal spaces IS in the Y direction is preferably, for example, 10 μm or more and 500 μm or less. In the example shown in FIG. 2 , internal spaces IS are further provided, arranged at a half pitch in each of the Y direction and the X direction.

[0037] As shown in FIG. 2 , when viewed from a plane normal to the first main surface of the optical laminate 100A, the first inclined surface ISa forms a curved surface convex toward the light source LS. When a plurality of LED devices arranged in the X direction are used as the light source LS, the light emitted from each LED device spreads in the Y direction. Therefore, the first inclined surface ISa acts uniformly on the light if the first inclined surface ISa has a curved surface convex toward the light source LS. Note that if a coupling optical system is provided between the light source LS and the light-receiving side surface 10a of the light guide layer 10 to allow highly parallel light (light with small spread in the Y direction) to be incident, the first inclined surface ISa may be parallel to the X direction. Furthermore, instead of the discrete internal space IS, an internal space such as a groove (e.g., a triangular prism) extending in the X direction may also be used.

[0038] As shown in FIG. 3, the cross-sectional shape of the internal space IS (the shape of a cross section perpendicular to the X direction in FIG. 1 and parallel to the YZ plane) is, for example, a triangle having an apex angle on the first main surface side (Z direction in FIG. 1) of the optical laminate 100A. The inclination angle θa of the first inclined surface ISa on the light source LS side is, for example, 10° or more and 70° or less. If the inclination angle θa is less than 10°, the controllability of the light distribution may decrease and the light extraction efficiency may also decrease. On the other hand, if the inclination angle θa exceeds 70°, it may be difficult to process, for example, the film constituting the light guide layer 10. Furthermore, the inclination angle θb of the second inclined surface ISb is, for example, 50° or more and 100° or less. If the inclination angle θb is less than 50°, stray light may be generated in an unintended direction. On the other hand, if the inclination angle θb exceeds 100°, it may be difficult to process, for example, the film constituting the light guide layer 10. Note that the cross-sectional shape of the internal space IS is not limited to the triangle exemplified here, but may be a trapezoid, etc.

[0039] As shown in Figure 4, the two-dimensional size of the internal space IS is determined by the length L and width W of the internal space IS. The length L of the internal space IS is preferably, for example, 10 µm or more and 500 µm or less. The width W of the internal space IS is preferably, for example, 1 µm or more and 100 µm or less. The length L of the internal space IS is, for example, at least twice the width W of the internal space IS. Furthermore, from the viewpoint of light extraction efficiency, the height H of the internal space IS (see Figure 3) is preferably, for example, 1 µm or more and 100 µm or less.

[0040] As described above, the lighting device 100A_L according to the embodiment of the present invention can provide illumination by directing light emitted from the light source LS and propagating through the light guide layer 10 toward the first principal surface using the light distribution control structure when the light source LS is turned on (light LRa in FIG. 1). Furthermore, when the light source LS is turned off, the lighting device 100A_L functions as a mirror by reflecting (specularly reflecting) external light incident on the optical laminate 100A by the mirror layer 1, as shown in FIG. 5 (light LRb in FIG. 5). Thus, the lighting device 100A_L according to the embodiment of the present invention can be used as a lighting device when the light source LS is turned on, and as a mirror when the light source LS is turned off. In other words, the lighting device 100A_L can be switched between a mode in which it functions as a lighting device (lighting mode) and a mode in which it functions as a mirror (mirror mode). Therefore, the lighting device 100A_L can be considered a design lighting device with an entirely new application.

[0041] Furthermore, since the lighting device 100A_L has a light distribution control structure having multiple internal spaces IS (i.e., utilizing total internal reflection), it has high light utilization efficiency and can achieve high transparency (visible light transmittance) and a low haze value for the light guide layer 10 (the portion of the optical laminate 100A excluding the mirror layer 1). From the perspective of viewing the mirror layer 1 (the image reflected on the mirror layer 1) through the light guide layer 10, it is preferable that the visible light transmittance of the light guide layer 10 be 60% or more, and that the haze value of the light guide layer 10 be less than 30%.

[0042] A possible device that functions as both a lighting device and a mirror is one in which a light source is disposed behind a half mirror. In this configuration, when the light source is turned on, illumination is provided by light emitted from the light source that passes through the half mirror. Furthermore, when the light source is turned off, the half mirror functions as a mirror by reflecting external light. However, in this configuration, the light reflectance of the half mirror is low, resulting in a dark mirror image in mirror mode. Furthermore, in lighting mode, a portion of the light emitted from the light source is reflected by the half mirror, resulting in low light utilization efficiency. In contrast, the lighting device 100A_L according to the embodiment of the present invention, having the above-described configuration, can prevent the mirror image from becoming dark in mirror mode and increase light utilization efficiency in lighting mode.

[0043] Another possible configuration is to use a lighting device called a front light, which functions as both a lighting device and a mirror, and is arranged in front of the mirror. However, with this configuration, the quality of the mirror image in mirror mode may be reduced if the light extraction structure (e.g., a dot pattern) formed on the light guide plate of the front light is visible. In contrast, the lighting device 100A_L according to the embodiment of the present invention can avoid such problems.

[0044] [Examples of Preferred Configurations of Light Guide Layer and Mirror Layer] The light guide layer 10 can be formed of a known material with high transmittance for visible light. The light guide layer 10 is formed of, for example, an acrylic resin such as polymethyl methacrylate (PMMA), a polycarbonate (PC) resin, a cycloolefin resin, or glass (for example, quartz glass, alkali-free glass, or borosilicate glass). The refractive index n of the light guide layer 10 is ＧＰ is, for example, 1.40 or more and 1.80 or less. Unless otherwise specified, the refractive index refers to a refractive index measured with an ellipsometer at a wavelength of 550 nm. The thickness of the light guide layer 10 can be set appropriately depending on the application. The thickness of the light guide layer 10 is, for example, 0.05 mm or more and 50 mm or less.

[0045] The light guide layer 10 having a light distribution control structure with multiple internal spaces IS is produced, for example, by laminating a first film having no pattern and a second film having a desired fine pattern formed thereon by a lamination method or by bonding them together with an adhesive (including a pressure-sensitive adhesive).

[0046] The second film can be micropatterned using laser patterning, direct laser imaging, laser drilling, masked or maskless laser or electron beam irradiation, or by printing, inkjet printing, screen printing, etc. Individual properties can be imparted to the second film to modify the material or refractive index value. Micro / nano-dispensing, dosing, direct "writing," discrete laser sintering, micro-electrical discharge machining (micro-EDM), or micromachining, micro-molding, imprinting, embossing, and the like can also be used.

[0047] A glass plate having a metal plating (e.g., aluminum plating or silver plating) on ​​its surface or a metal plate (e.g., aluminum plate) can be used as the mirror layer 1. Alternatively, a reflective film having a multilayer film structure formed from a resin can also be used as the mirror layer 1.

[0048] The light guide layer 10 and the mirror layer 1 can be bonded together via, for example, an adhesive layer. Here, the term "adhesive" includes a pressure-sensitive adhesive (also called a pressure-sensitive adhesive).

[0049] [Configuration Having Antireflection Layer] Another lighting device 100B_L according to an embodiment of the present invention will be described with reference to Fig. 6. Fig. 6 is a cross-sectional view schematically showing the lighting device 100B_L. The following description will focus on differences between the lighting device 100B_L and the lighting device 100A_L shown in Fig. 1.

[0050] 6 , the optical laminate 100B included in the lighting device 100B_L differs from the optical laminate 100A of the lighting device 100A_L in that the optical laminate 100B further includes an antireflection layer 20. The antireflection layer 20 is disposed on the third main surface 10b side of the light guide layer 10, that is, on the first main surface (light exit surface) side with respect to the light distribution control structure.

[0051] In the lighting device 100B_L, the antireflection layer 20 is provided, so that surface reflection on the first main surface of the optical laminate 100B can be suppressed.

[0052] For example, a multilayer laminate made up of a plurality of thin films with different refractive indices can be used as the anti-reflection layer 20. Examples of materials for the thin films constituting the multilayer laminate include metal oxides, nitrides, and fluorides.

[0053] The antireflection layer 20 is preferably an alternate laminate of high refractive index layers and low refractive index layers. The refractive index of the high refractive index layers is, for example, 1.9 or more, preferably 2.0 or more. Materials for the high refractive index layers include titanium oxide, niobium oxide, zirconium oxide, tantalum oxide, zinc oxide, indium oxide, indium tin oxide (ITO), antimony-doped tin oxide (ATO), etc. Among these, titanium oxide or niobium oxide is preferred. The refractive index of the low refractive index layers is, for example, 1.6 or less, preferably 1.5 or less. Materials for the low refractive index layers include silicon oxide, titanium nitride, magnesium fluoride, barium fluoride, calcium fluoride, hafnium fluoride, lanthanum fluoride, etc. Among these, silicon oxide is preferred. In particular, niobium oxide (Nb ２ O ５ ) thin film as a low refractive index layer, and silicon oxide (SiO ２ In addition to the low refractive index layer and the high refractive index layer, a medium refractive index layer having a refractive index of about 1.6 to 1.9 may be provided.

[0054] The thickness of each of the high-refractive-index layer and the low-refractive-index layer is about 5 nm to 200 nm, preferably about 15 nm to 150 nm, and may be determined based on the refractive index, layer structure, etc., to reduce the reflectance of visible light.

[0055] The method for forming the thin film that constitutes the anti-reflection layer 20 is not particularly limited, and either a wet coating method or a dry coating method may be used. Dry coating methods such as vacuum deposition, CVD, sputtering, and electron beam deposition are preferred because they can form a thin film with a uniform thickness. Among these, sputtering is preferred because it has excellent film thickness uniformity and is easy to form a dense film. For example, the anti-reflection layer described in JP 2020-52221 A can be suitably used. The entire disclosure of JP 2020-52221 A is incorporated herein by reference.

[0056] [Configuration Having an Antifouling Layer] Still another lighting device 100C_L according to an embodiment of the present invention will be described with reference to Fig. 7. Fig. 7 is a cross-sectional view schematically showing the lighting device 100C_L. The following description will focus on differences between the lighting device 100C_L and the lighting device 100A_L shown in Fig. 1.

[0057] 7 , the optical laminate 100C included in the lighting device 100C_L differs from the optical laminate 100A of the lighting device 100A_L in that the optical laminate 100C further includes an antifouling layer 30. The antifouling layer 30 is water-repellent and / or oil-repellent (hydrophilic). The antifouling layer 30 is disposed on the third main surface 10b side of the light guide layer 10, and is provided as the outermost layer on the first main surface (light-emitting surface) side of the optical laminate 100C.

[0058] In the lighting device 100C_L, the antifouling layer 30 is provided, thereby making it possible to prevent adhesion of dirt to the optical laminate 100C.

[0059] The configuration of the antifouling layer 30 is selected appropriately depending on the application. The antifouling layer 30 can be formed using known materials. Silicone compounds or fluorine-containing compounds are preferred as materials for the antifouling layer 30. Among them, fluorine-containing compounds have excellent water repellency and can exhibit high antifouling properties, and fluorine-based polymers containing a perfluoropolyether skeleton are particularly preferred. From the viewpoint of enhancing antifouling properties, perfluoropolyethers having a main chain structure that can be rigidly aligned are particularly preferred. As the structural unit of the main chain skeleton of perfluoropolyether, perfluoroalkylene oxides having 1 to 4 carbon atoms which may have branches are preferred, for example, perfluoromethylene oxide, (-CF ２ O-), perfluoroethylene oxide (-CF ２ CF ２ O-), perfluoropropylene oxide (-CF ２ CF ２ CF ２ O-), perfluoroisopropylene oxide (-CF(CF ３ )CF ２ O-) and the like.

[0060] The thickness of the antifouling layer 30 is preferably 3 nm or more and 15 nm or less, and more preferably 3 nm or more and 10 nm or less.

[0061] Depending on the material, the anti-fouling layer 30 can be formed by physical vapor deposition methods such as vapor deposition and sputtering, chemical vapor deposition methods, or wet coating methods such as reverse coating, die coating, and gravure coating. For example, the anti-fouling layer described in JP 2020-067582 A can be suitably used. The entire disclosure of JP 2020-067582 A is incorporated herein by reference.

[0062] An antireflection layer may be disposed on the light guide layer 10 side of the antifouling layer 30 (between the antifouling layer 30 and the light guide layer 10).

[0063] [Configuration with Polarized-Light Selective Reflection Layer] Still another lighting device 100D_L according to an embodiment of the present invention will be described with reference to Fig. 8. Fig. 8 is a cross-sectional view schematically showing the lighting device 100D_L. The following description will focus on differences between the lighting device 100D_L and the lighting device 100A_L shown in Fig. 1.

[0064] As shown in FIG. 8 , the optical laminate 100D included in the lighting device 100D_L differs from the optical laminate 100A of the lighting device 100A_L in that it further includes a polarized light selective reflection layer 40. The polarized light selective reflection layer 40 is disposed on the third main surface 10b side of the light guide layer 10, that is, on the first main surface (light exit surface) side with respect to the light distribution control structure. The polarized light selective reflection layer 40 selectively reflects light of a specific polarization state (polarization direction) and transmits light of other polarization states. For example, the polarized light selective reflection layer 40 selectively reflects one of two orthogonal polarization components contained in light and transmits the other polarization component.

[0065] The illumination device 100D_L functions as a polarized illumination device because, in the illumination mode, it can selectively emit light in a certain polarization state (polarization direction) from the first main surface of the optical laminate 100D due to the provision of the polarized light selective reflection layer 40. The illumination device 100D_L that can function as a polarized illumination device in this way can be suitably used for, for example, the following applications.

[0066] The applicant of the present application proposed an anti-peeping system in International Publication No. 2021 / 200722 that can prevent external peeping. This anti-peeping system includes a display device and a partition that separates a space in which a display is provided by the display device from the surrounding area. The display device has a first polarizing layer on the front surface of the display surface, the first polarizing layer having a first absorption axis parallel to a first direction (e.g., one of the horizontal and vertical directions). The partition has a light-transmitting portion that allows viewing into the space. The light-transmitting portion of the partition is disposed on the space side of the transparent substrate and has a second polarizing layer having a second absorption axis parallel to a second direction (e.g., the other of the horizontal and vertical directions). This configuration can prevent external peeping of the display provided by the display device.

[0067] When the lighting device 100D_L is placed in a room (for example, a conference room) in which this anti-peeping system is used, the visibility of the lighting from outside in the lighting mode can be reduced.

[0068] Furthermore, when the illumination device 100D_L is used as a backlight for a liquid crystal display device, the light extraction efficiency can be further improved.

[0069] A multilayer optical film such as DBEF manufactured by 3M can be used as the polarized light selective reflection layer 40. The polarization degree of the polarized light selective reflection layer 40 is, for example, 90% or more, and preferably 99% or more.

[0070] As shown in FIG. 9, an antireflection layer 20 may be provided on the polarized-light selective reflection layer 40 (on the first main surface side of the polarized-light selective reflection layer 40).

[0071] [Another Configuration Including a Polarized-Light Selective Reflection Layer] Still another lighting device 100E_L according to an embodiment of the present invention will be described with reference to Fig. 10. Fig. 10 is a cross-sectional view schematically showing the lighting device 100E_L. The following description will focus on differences between the lighting device 100E_L and the lighting device 100D_L shown in Fig. 8.

[0072] 10 , the optical stack 100E included in the lighting device 100E_L differs from the optical stack 100D of the lighting device 100D_L in that the optical stack 100E further includes a direction changing layer 60. The direction changing layer 60 is provided on the third major surface 10b side of the light guide layer 10.

[0073] In lighting device 100E_L, the light distribution control structure having multiple internal spaces IS is formed in direction changing layer 60, not in light guide layer 10. In this specification, the light distribution control structure formed in direction changing layer 60 may be referred to as the "second light distribution control structure." The light distribution control structure (second light distribution control structure) of lighting device 100E_L also directs a portion of the light propagating in light guide layer 10 toward the first principal surface.

[0074] 11 shows an example of a specific configuration of a direction changing layer 60 having a light distribution control structure formed thereon. In the example shown in FIG. 11, the direction changing layer 60 is composed of a shaped film 62 having a fifth main surface 62a with a plurality of recesses 62r, and an adhesive layer 64 arranged on the fifth main surface 62a side of the shaped film 62. The adhesive layer 64 is located between the shaped film 62 and the light guide layer 10, and the adhesive layer 64 bonds the light guide layer 10 and the shaped film 62. The plurality of internal spaces IS are defined by the plurality of recesses 62r of the shaped film 62 and the adhesive layer 64.

[0075] The shaped film 62 for forming the internal space IS can be produced, for example, by the method described in JP-A-2013-524288. Specifically, for example, the surface of a polymethyl methacrylate (PMMA) film is coated with lacquer (for example, FineCure RM-64 manufactured by Sanyo Chemical Industries, Ltd.), an optical pattern is embossed on the film surface containing the lacquer, and then the lacquer is cured to produce the shaped film 62A.

[0076] The thickness of the adhesive layer 64 is, for example, 0.1 μm to 100 μm, preferably 0.3 μm to 100 μm, and more preferably 0.5 μm to 50 μm. The refractive index of the adhesive layer 64 is preferably 1.42 to 1.60, and more preferably 1.47 to 1.58. The refractive index of the adhesive layer 64 is preferably close to the refractive index of the light guide layer 10 or the shaped film 62, and the absolute value of the difference between the refractive indices is preferably 0.2 or less.

[0077] Specific examples of adhesives include rubber-based adhesives, acrylic-based adhesives, silicone-based adhesives, epoxy-based adhesives, cellulose-based adhesives, and polyester-based adhesives. These adhesives may be used alone or in combination of two or more.

[0078] The adhesive layer 64 is preferably capable of adhering without filling the recesses 62r on the surface of the shaped film 62. Suitable adhesives for forming the adhesive layer 64 include those described in International Publication Nos. 2021 / 167090, 2021 / 167091, or International Application PCT / JP2022 / 004554 by the present applicant. The entire disclosures of these applications are incorporated herein by reference. In particular, polyester-based adhesives described in International Application PCT / JP2022 / 004554 are preferred.

[0079] Although not shown here, the shaped film 62 and the polarized-light selective reflection layer 40 can be bonded together with an adhesive layer.

[0080] 10 illustrates a configuration in which the direction changing layer 60 is provided on the third major surface 10b side of the light guide layer 10, but the arrangement of the direction changing layer 60 is not limited to this. Fig. 12 shows another example of the arrangement of the direction changing layer 60. In the example shown in Fig. 12, the direction changing layer 60 is provided on the fourth major surface 10c side of the light guide layer 10 (i.e., between the light guide layer 10 and the mirror layer 1).

[0081] [Configuration Including a Quarter Wave Plate in Addition to a Polarized-Light Selective Reflection Layer] Still another lighting device 100F_L according to an embodiment of the present invention will be described with reference to Fig. 13. Fig. 13 is a cross-sectional view schematically showing the lighting device 100F_L. The following description will focus on the differences between the lighting device 100F_L and the lighting device 100E_L shown in Fig. 10.

[0082] 13 , the optical laminate 100F included in the lighting device 100F_L differs from the optical laminate 100E of the lighting device 100E_L in that the lighting device 100F_L further includes a quarter-wave plate 70. The quarter-wave plate 70 is disposed between the polarization selective reflection layer 40 and the mirror layer 1, and more specifically, on the fourth main surface 10c side of the light guide layer 10 (i.e., between the light guide layer 10 and the mirror layer 1).

[0083] In the lighting device 100F_L, by providing the quarter-wave plate 70 as described above, it is possible to change the polarization state of light that is directed toward the first principal surface by the light distribution control structure and that is reflected by the polarized light selective reflection layer 40 (i.e., light that could not pass through the polarized light selective reflection layer 40) to a state that allows it to pass through the polarized light selective reflection layer 40 (to a polarization direction perpendicular to the original polarization direction), thereby increasing the light utilization efficiency.

[0084] Various known quarter-wave plates can be used as the quarter-wave plate 70. Although FIG. 13 shows an example in which the quarter-wave plate 70 is arranged on the fourth main surface 10c side of the light guide layer 10, the arrangement of the quarter-wave plate 70 is not limited to this. FIG. 14 shows another example of the arrangement of the quarter-wave plate 70. In the example shown in FIG. 14, the quarter-wave plate 70 is arranged between the direction converting layer 60 and the polarization selective reflection layer 40. The quarter-wave plates 70 in the arrangements shown in FIG. 13 and FIG. 14 are optically equivalent and function in the same way.

[0085] [Other Examples of Light Distribution Control Structure] In the explanations given so far, a light distribution control structure has been exemplified in which a portion of the light propagating within the light guide layer 10 is directed toward the first principal surface side. However, the light distribution control structure may also be configured to direct a portion of the light propagating within the light guide layer 10 toward the second principal surface side.

[0086] For example, the light distribution control structure (first light distribution control structure) formed in the light guide layer 10 may have a plurality of internal spaces IS that form interfaces that direct a portion of the light propagating within the light guide layer 10 toward the second main surface by total internal reflection, as in the lighting device 100A_L shown in Fig. 15. The cross-sectional shape of these internal spaces IS is, for example, a triangle with an apex angle on the second main surface side of the optical laminate 100A (-Z direction in Fig. 15).

[0087] Furthermore, the light distribution control structure (second light distribution control structure) formed in the direction converting layer 60 may have a plurality of internal spaces IS that form interfaces that direct a portion of the light propagating within the light guide layer 10 toward the second main surface by total internal reflection, as in the lighting device 100E_L shown in Fig. 16. The cross-sectional shape of these internal spaces IS is, for example, a triangle with an apex angle on the second main surface side of the optical laminate 100A (-Z direction in Fig. 16).

[0088] With the light distribution control structure configured in this manner, light directed toward the second principal surface is reflected by mirror layer 1 toward the first principal surface and is emitted from the first principal surface. Therefore, even when the light distribution control structure is configured to direct a portion of the light propagating within light guide layer 10 toward the second principal surface, illumination can be performed favorably.

[0089] [Other Configurations] Still another lighting device 100G_L according to an embodiment of the present invention will be described with reference to Fig. 17. Fig. 17 is a cross-sectional view schematically showing lighting device 100G_L. The following description will focus on differences between lighting device 100G_L and lighting device 100E_L shown in Fig. 10.

[0090] 17, the optical laminate 100G included in the lighting device 100G_L further includes an optical coupling layer 80 provided between the light guide layer 10 and the direction converting layer 60. The optical coupling layer 80 has a refractive index n ＧＰ A refractive index n smaller than Ｃ Each of the low refractive index regions 80a is formed in the shape of a dot having a size of, for example, 1 μm or more and 1000 μm or less.

[0091] In the lighting device 100G_L, the optical coupling layer 80 having a plurality of low refractive index regions 80a is provided, thereby enabling light propagating through the light guide layer 10 to be more selectively and efficiently guided to the direction conversion layer 60. Furthermore, the uniformity of the emitted light can be controlled by adjusting the arrangement density of the plurality of low refractive index regions 80a. For example, the uniformity of the light can be improved by arranging the low refractive index regions 80a so that they are denser on the light source LS side and sparser as they move away from the light source LS.

[0092] 18, the polarization selective reflection layer 40 of the lighting device 100G_L may be omitted. The effect of providing the optical coupling layer 80 can also be obtained in a configuration in which the polarization selective reflection layer 40 is omitted as shown in FIG. 18. The direction changing layer 60 may also be provided on the fourth major surface 10c side of the light guide layer 10 (i.e., between the light guide layer 10 and the mirror layer 1). Even in a configuration in which the direction changing layer 60 is provided on the fourth major surface 10c side of the light guide layer 10, the same effect can be obtained by providing the optical coupling layer 80 between the light guide layer 10 and the direction changing layer 60.

[0093] The refractive index n of the low refractive index region 80a Ｃ is preferably 1.05 or more and 1.30 or less, and more preferably 1.05 or more and 1.25 or less. ＧＰ and the refractive index n of the low refractive index region 80a Ｃ The difference between the refractive index n and the refractive index n is preferably 0.20 or more, more preferably 0.23 or more, and even more preferably 0.25 or more. Ｃ The low refractive index region 80a having a refractive index of 1.30 or less may be, for example, a porous region having a void structure therein. The thickness of the low refractive index region 80a is, for example, 0.3 μm or more and 5 μm or less.

[0094] When the low refractive index region 80a is a porous region, its porosity is preferably 35 vol% or more, more preferably 38 vol% or more, and particularly preferably 40 vol% or more. Within this range, a low refractive index region 80a with a particularly low refractive index can be formed. The upper limit of the porosity is, for example, 90 vol% or less, preferably 75 vol% or less. Within this range, a low refractive index region 80a with excellent strength can be obtained. The porosity is calculated from the refractive index value measured with an ellipsometer using the Lorentz-Lorenz formula.

[0095] For the low refractive index region 80a, for example, a low refractive index layer having a void structure disclosed in International Publication No. 2019 / 146628 can be used. The entire disclosure of International Publication No. 2019 / 146628 is incorporated herein by reference. Specifically, the low refractive index region 80a having a void structure may contain silica particles, silica particles having micropores, approximately spherical particles such as hollow silica nanoparticles, fibrous particles such as cellulose nanofibers, alumina nanofibers, and silica nanofibers, and flat particles such as nanoclay composed of bentonite. The low refractive index region 80a having a void structure may be a porous body formed by direct chemical bonding of particles (e.g., microporous particles). Furthermore, at least a portion of the particles constituting the low refractive index region 80a having a void structure may be bonded to each other via a small amount (e.g., less than the mass of the particles) of a single binder component. The porosity and refractive index n of the low refractive index region 80a Ｃ can be adjusted by the particle size, particle size distribution, etc. of the particles that make up the low refractive index region 80a.

[0096] Methods for obtaining the low refractive index region 80a having a void structure include, for example, methods described in JP 2010-189212 A, JP 2008-040171 A, JP 2006-011175 A, WO 2004 / 113966 A, and references thereto. The disclosures of JP 2010-189212 A, JP 2008-040171 A, JP 2006-011175 A, and WO 2004 / 113966 A are all incorporated herein by reference.

[0097] A porous silica body can be suitably used as the low refractive index region 80a having a void structure. The porous silica body can be produced by, for example, the following methods. Examples include a method of hydrolyzing and polycondensing a silicon compound; hydrolyzable silanes and / or silsesquioxane, and at least one of their partial hydrolyzates and dehydrated condensates; a method using porous particles and / or hollow fine particles; a method of producing an aerogel layer by utilizing the springback phenomenon; and a method using a pulverized gel in which a gel-like silicon compound obtained by a sol-gel method is pulverized and the resulting pulverized microporous particles are chemically bonded together with a catalyst or the like. However, the low refractive index region 80a is not limited to a porous silica body, and the production method is not limited to the exemplified production method; any production method may be used. The silsesquioxane may be (RSiO １．５ , R is a hydrocarbon group) as a basic structural unit, and ２ Although it is strictly different from silica, which has silsesquioxane as a basic structural unit, it has something in common with silica in that it has a network structure cross-linked by siloxane bonds. Therefore, in this specification, porous materials containing silsesquioxane as a basic structural unit are also referred to as porous silica materials or silica-based porous materials.

[0098] The porous silica material can be composed of microporous particles of a gel-like silicon compound bonded to one another. Examples of the microporous particles of the gel-like silicon compound include pulverized gel-like silicon compounds. The porous silica material can be formed, for example, by applying a coating liquid containing pulverized gel-like silicon compounds to a substrate. The pulverized gel-like silicon compounds can be chemically bonded (e.g., siloxane bonded) by, for example, the action of a catalyst, light irradiation, heating, etc.

[0099] Still another lighting device 100H_L according to an embodiment of the present invention will be described with reference to Fig. 19. Fig. 19 is a cross-sectional view schematically showing the lighting device 100H_L. The following description will focus on differences between the lighting device 100H_L and the lighting device 100G_L shown in Fig. 18.

[0100] As shown in FIG. 19 , the optical laminate 100H included in the lighting device 100H_L has a first region R1 in which a light distribution control structure is present (i.e., an internal space IS is formed) and a second region R2 in which a light distribution control structure is not present (i.e., an internal space IS is not formed). The first region R1 and the second region R2 are arranged so as to define a predetermined pattern when viewed in a planar view from the normal direction to the first main surface. Here, the "pattern" includes letters, numbers, symbols, pictures, designs, and combinations thereof. In the illustrated example, the optical laminate 100H does not have an optical coupling layer 80, but may have an optical coupling layer 80.

[0101] An example of the arrangement of the first region R1 and the second region R2 is shown in Fig. 20. Fig. 20 shows a state in which the lighting device 100H_L is turned on.

[0102] As shown in Fig. 20 , the first region R1 where the light distribution control structure is present is a region that emits light in the lit state (light-emitting region), and the second region R2 where the light distribution control structure is not present is a region that does not substantially emit light in the lit state (non-light-emitting region). Needless to say, the patterns defined by the first region R1 and the second region R2 are not limited to those exemplified in Fig. 20 .

[0103] In this way, in lighting device 100H_L, the first region R1 where the light distribution control structure is present and the second region R2 where the light distribution control structure is not present are arranged to define a predetermined pattern, so that light can be emitted in the form of a predetermined pattern in lighting mode, thereby achieving lighting (light emission) that is rich in design and entertainment value.

[0104] In the example shown in FIG. 20 , the first region R1 and the second region R2 are arranged to define the word "EXIT" and an arrow. Therefore, the lighting device 100H_L can be used as a mirror in mirror mode during normal times and as an evacuation light indicating the evacuation direction in lighting mode during an emergency. While constantly displaying emergency evacuation signs (evacuation lights) can detract from the aesthetic appeal of a facility or building, using the lighting device 100H_L in this manner can prevent such degradation. Thus, the lighting device 100H_L can be used for more practical purposes depending on the design, and can function as a mirror during normal times, preventing aesthetic degradation even when used for practical purposes.

[0105] Still another lighting device 100I_L according to an embodiment of the present invention will be described with reference to Fig. 21. Fig. 21 is a cross-sectional view schematically showing the lighting device 100I_L. The following description will focus on differences between the lighting device 100I_L and the lighting device 100G_L shown in Fig. 18.

[0106] 21 , the optical laminate 100I included in the lighting device 100I_L has a first region R1′ where the optical coupling layer 80 is present and a second region R2′ where the optical coupling layer 80 is not present. The first region R1′ and the second region R2′ are arranged so as to define a predetermined pattern when viewed in a plan view from the normal direction to the first main surface.

[0107] In the first region R1' where the optical coupling layer 80 is present (i.e., where the low refractive index region 80a is formed), light propagating within the light guide layer 10 is less likely to reach the light distribution control structure (internal space IS) due to total reflection at the optical coupling layer 80. Therefore, the first region R1' where the optical coupling layer 80 is present is a region (low-brightness light-emitting region) that emits light at a relatively low luminance (or does not emit light substantially) in the lit state. In contrast, the second region R2' where the optical coupling layer 80 is not present (i.e., where the low refractive index region 80a is not formed) is a region (high-brightness light-emitting region) that emits light at a relatively high luminance in the lit state.

[0108] In this way, in the lighting device 100I_L, the first region R1′ where the optical coupling layer 80 is present and the second region R2′ where the optical coupling layer 80 is not present are arranged to define a predetermined pattern, so that light can be emitted in the lighting mode so that the predetermined pattern is visible. Therefore, lighting (light emission) that is rich in design and entertainment value can be realized.

[0109] The low refractive index region 80a can be selectively formed in the first region R1′ by a coating method or a printing method. When using a coating method, coating can be performed using a mask having a predetermined pattern. The printing method can be a plate-based printing method such as gravure printing, or a plateless printing method such as inkjet printing.

[0110] According to an embodiment of the present invention, it is possible to provide a lighting device that is rich in design or entertainment value and an optical laminate that is suitable for use in such a lighting device. The lighting device according to an embodiment of the present invention is a device with an entirely new application that can be used by switching between a lighting mode and a mirror mode, and can be used, for example, as a building component.

[0111] DESCRIPTION OF SYMBOLS 1 Mirror layer 10 Light guide layer 10a Light receiving side surface of light guide layer 10b Third main surface of light guide layer 10c Fourth main surface of light guide layer 20 Anti-reflection layer 30 Anti-fouling layer 40 Polarized light selective reflection layer 60 Direction conversion layer 62 Shaped film 62r Recess of shaped film 64 Adhesive layer 70 1 / 4 wavelength plate 80 Optical coupling layer 80a Low refractive index region 100A, 100B, 100C, 100D, 100E, 100F Optical laminate 100G, 100H, 100I Optical laminate 100A_L, 100B_L, 100C_L Lighting device 100D_L, 100E_L, 100F_L Lighting device 100G_L, 100H_L, 100I_L Illumination device IS Internal space ISa First slope ISb Second slope LS Light source R1, R1' First region R2, R2' Second region

Claims

1. An optical laminate having a first major surface and a second major surface opposite to the first major surface, a light-receiving portion that receives light emitted from a light source, a light guide layer having a third major surface on the first major surface side and a fourth major surface on the second major surface side, a mirror layer having light reflectivity disposed on the fourth major surface side of the light guide layer, a light distribution control structure having a plurality of internal spaces, wherein the plurality of internal spaces form an interface that directs a part of the light propagating in the light guide layer toward the first major surface side or the second major surface side by total internal reflection, and an optical laminate having the same.

2. The optical laminate according to claim 1, further comprising a polarization selective reflection layer disposed on the first major surface side with respect to the light distribution control structure.

3. The optical laminate according to claim 2, further comprising a quarter-wave plate disposed between the polarization selective reflection layer and the mirror layer.

4. The optical laminate according to any one of claims 1 to 3, further comprising an antireflection layer disposed on the first major surface side with respect to the light distribution control structure.

5. The optical laminate according to any one of claims 1 to 3, further comprising an antifouling layer having water repellency and / or oil repellency as the outermost layer on the first major surface side.

6. The optical laminate according to any one of claims 1 to 3, wherein the light distribution control structure includes a first light distribution control structure in which the plurality of internal spaces are formed in the light guide layer.

7. The optical laminate according to any one of claims 1 to 3, wherein the light distribution control structure includes a second light distribution control structure in which the plurality of internal spaces are formed in a direction conversion layer provided on the third major surface side or the fourth major surface side of the light guide layer.

8. Further comprising a light coupling layer provided between the light guide layer and the direction conversion layer, The optical laminate according to claim 7, wherein the optical coupling layer has a plurality of low refractive index regions having a refractive index smaller than that of the light guide layer.

9. The optical laminate according to any one of claims 1 to 3, wherein when viewed in plan from the normal direction to the first main surface, a first region where the light distribution control structure exists and a second region where the light distribution control structure does not exist are arranged so as to define a predetermined pattern.

10. The optical laminate according to claim 8, wherein when viewed in plan from the normal direction to the first main surface, a first region where the optical coupling layer exists and a second region where the optical coupling layer does not exist are arranged so as to define a predetermined pattern.

11. The optical laminate according to any one of claims 1 to 3, a light source that emits light toward the light receiving unit, and a lighting device comprising the same.