Optical laminates and illumination devices

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

[Technical Field]

[0001] This invention relates to an optical laminate and an illumination device. [Background technology]

[0002] To improve the convenience of using a mirror, illuminated mirrors are known, which are equipped with a lighting device to illuminate the user. Illuminated mirrors are disclosed, for example, in Patent Documents 1 and 2.

[0003] In the illuminated mirror disclosed in Patent Document 1, illumination is achieved when light emitted diagonally upward from a light source located on the back side of the mirror is reflected diagonally downward from the front by a reflective member located above the mirror. In the illuminated mirror disclosed in Patent Document 2, a ring-shaped light-transmitting portion is provided on the outer edge of the mirror, and illumination is achieved when 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. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2019-139995 [Patent Document 2] Japanese Patent Publication No. 2019-154994 [Overview of the Initiative] [Problems that the invention aims to solve]

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

[0006] The embodiments of the present invention aim to provide a lighting device that is highly aesthetically pleasing or entertaining, and an optical laminate that is suitably used in such a lighting device. [Means for solving the problem]

[0007] According to embodiments of the present invention, the following solutions are provided.

[0008] [Item 1] An optical laminate having a first principal surface and a second principal surface opposite to the first principal surface, A light-receiving section that receives light emitted from a light source, and a light-guiding layer having a third main surface on the first main surface side and a fourth main surface on the second main surface side, A light-reflective mirror layer is disposed on the fourth main surface side of the light guide layer, A light distribution control structure having multiple internal spaces, wherein the multiple internal spaces form interfaces that direct a portion of the light propagating within the light guide layer toward the first main surface side or the second main surface side by total internal reflection, An optical laminate having [a certain characteristic].

[0009] [Item 2] The optical laminate according to item 1, further comprising a polarization selective reflective 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 polarization selective reflective layer and the mirror layer.

[0011] [Item 4] The optical laminate according to items 1 to 3, further comprising an anti-reflective layer disposed on the first main surface side with respect to the light distribution control structure.

[0012] [Item 5] The optical laminate according to 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 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 within the light guide layer.

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

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

[0016] [Item 9] When viewed in plan from the normal direction with respect 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, and the optical laminate according to any one of Items 1 to 8.

[0017] [Item 10] When viewed in plan from the normal direction with respect to the first main surface, a first region where the light coupling layer exists and a second region where the light coupling layer does not exist are arranged so as to define a predetermined pattern, and the optical laminate according to Item 8.

[0018] [Item 11] The optical laminate according to any one of Items 1 to 10, A light source that emits light toward the light receiving portion, And a lighting device. [Advantages of the Invention]

[0019] According to an embodiment of the present invention, it is possible to provide a lighting device rich in design or entertainment and an optical laminate suitably used for such a lighting device. [Brief Description of the Drawings]

[0020] [Figure 1] It is a cross-sectional view schematically showing a lighting device 100A_L according to an embodiment of the present invention. [Figure 2] This is a schematic plan view of the lighting device 100A_L. [Figure 3] This is a schematic cross-sectional view showing the internal space IS of the light distribution control structure of the lighting device 100A_L. [Figure 4] This is a schematic plan view showing the internal space IS. [Figure 5] This is a schematic cross-sectional view of the lighting device 100A_L. [Figure 6] This is a schematic cross-sectional view showing another lighting device 100B_L according to an embodiment of the present invention. [Figure 7] This is a schematic cross-sectional view showing yet another lighting device 100C_L according to an embodiment of the present invention. [Figure 8] This is a schematic cross-sectional view showing yet another lighting device 100D_L according to an embodiment of the present invention. [Figure 9] This is a schematic cross-sectional view of the lighting device 100D_L. [Figure 10] This is a schematic cross-sectional view showing yet another lighting device 100E_L according to an embodiment of the present invention. [Figure 11] This is a schematic cross-sectional view of the lighting device 100E_L. [Figure 12] This is a schematic cross-sectional view of the lighting device 100E_L. [Figure 13] This is a schematic cross-sectional view showing yet another lighting device 100F_L according to an embodiment of the present invention. [Figure 14] This is a schematic cross-sectional view of the lighting device 100F_L. [Figure 15] This is a schematic cross-sectional view of the lighting device 100A_L. [Figure 16] This is a schematic cross-sectional view of the lighting device 100E_L. [Figure 17] This is a schematic cross-sectional view showing yet another lighting device 100G_L according to an embodiment of the present invention. [Figure 18] This is a schematic cross-sectional view of the lighting device 100G_L. [Figure 19]This is a schematic cross-sectional view showing yet another lighting device 100H_L according to an embodiment of the present invention. [Figure 20] This is a plan view showing an example of the arrangement of the first region R1 and the second region R2 of the lighting device 100H_L. [Figure 21] This is a schematic cross-sectional view showing yet another lighting device 100I_L according to an embodiment of the present invention. [Modes for carrying out the invention]

[0021] The optical laminate and illumination device according to embodiments of the present invention will be described below with reference to the drawings. However, the optical laminate and illumination device according to embodiments of the present invention are not limited to those illustrated in the following description.

[0022] [Configuration of optical laminate and illumination device] The lighting device 100A_L according to an embodiment of the present invention will be described with reference to Figure 1. Figure 1 is a schematic cross-sectional view showing the lighting device 100A_L.

[0023] As shown in Figure 1, the lighting device 100A_L comprises a light source LS and an optical laminate 100A. As will be described later, the lighting device 100A_L functions to illuminate the area in front when the light source LS is lit, while functioning as a mirror when the light source LS is turned off.

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

[0025] The optical laminate 100A has a first main surface and a second main surface opposite to the first main surface. In Figure 1, the upper main surface is the first main surface, and the lower main surface is the second main surface. When the illumination device 100A_L is functioning 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 (back side).

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

[0027] The optical laminate 100A has 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 to the light-emitting surface side). In the illustrated example, 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. Also, in the illustrated example, since the light guide layer 10 is located on the outermost surface of the first main surface side of the optical laminate 100A, the third main surface 10b of the light guide layer 10 is the first main surface of the optical laminate 100A.

[0029] The mirror layer 1 is located on the fourth main surface 10c side of the light guide layer 10. The mirror layer 1 is light reflective. 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 of the light distribution control structure form interfaces that direct a portion of the light propagating within the light guide layer 10 toward the first main surface by total internal reflection (TIR). Each internal space IS has a first inclined surface ISa that directs a portion of the light propagating within the light guide layer 10 toward the first main 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 multiple internal spaces IS is formed within the light guide layer 10. In this specification, the light distribution control structure formed within the light guide layer 10 may be referred to as the "first light distribution control structure".

[0032] By adjusting the cross-sectional shape, size, arrangement density, and distribution of the internal space IS, the light distribution of light emitted from the first main surface of the optical laminate 100A can be controlled. 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, preferably 80% or more. The haze value of the light guide layer 10 is, for example, less than 30%, preferably less than 10%. Here, visible light is defined as light with a wavelength of 380 nm to 780 nm. The visible light transmittance and haze value can be measured, for example, using a haze meter (manufactured by Murakami Color Technology Laboratory: product name HM-150).

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

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

[0036] As shown in Figure 2, the multiple internal spaces IS can be discretely arranged, for example, in the light-guiding direction (Y direction) of the light-guiding layer 10 and in directions intersecting the light-guiding direction. The discrete arrangement may or may not have periodicity (regularity) in at least one direction. However, from the viewpoint of mass production, it is preferable that the multiple internal spaces IS are uniformly arranged. For example, in the example shown in Figure 2, multiple internal spaces IS having substantially the same shape and a curved surface convex in the same direction are discretely and periodically arranged in the light-guiding direction (Y direction) of the light-guiding plate 10 and in a direction perpendicular to the light-guiding 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 Figure 2, further internal spaces IS are provided that are offset by half a pitch in both the Y direction and the X direction.

[0037] As shown in Figure 2, when viewed from a plane from the direction normal to the first main surface of the optical laminate 100A, the first inclined surface ISa forms a curved surface that is convex toward the light source LS. When multiple LED devices arranged in the X direction are used as the light source LS, the light emitted from each LED device has a spread in the Y direction, so having a curved surface that is convex toward the light source LS allows the first inclined surface ISa to act uniformly on the light. However, if a coupled optical system is provided between the light source LS and the light-receiving side surface 10a of the light guide layer 10, and light with high parallelism (light with small spread in the Y direction) is incident, the first inclined surface ISa may be parallel to the X direction. Also, instead of a discrete internal space IS, there may be an internal space such as a groove (e.g., a triangular prism) extending in the X direction.

[0038] As shown in Figure 3, the cross-sectional shape of the internal space IS (the shape of the cross section perpendicular to the X direction and parallel to the YZ planes in Figure 1) is, for example, a triangle with its apex angle on the first main surface side of the optical laminate 100A (the Z direction in Figure 1). The inclination angle θa of the first inclined surface ISa on the light source LS side is, for example, 10° to 70°. If the inclination angle θa is less than 10°, the controllability of light distribution decreases, and the light extraction efficiency may also decrease. On the other hand, if the inclination angle θa exceeds 70°, for example, it may become difficult to process the film constituting the light guide layer 10. The inclination angle θb of the second inclined surface ISb is, for example, 50° to 100°. If the inclination angle θb is less than 50°, stray light may be generated in unintended directions. On the other hand, if the inclination angle θb exceeds 100°, for example, it may become difficult to process 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 also be a trapezoid or the like.

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

[0040] As described above, when the light source LS is lit, the lighting device 100A_L according to the embodiment of the present invention can provide illumination by directing the light emitted from the light source LS and propagating within the light guide layer 10 toward the first main surface side using the light distribution control structure (light LRa in Figure 1). Furthermore, when the light source LS is turned off, the lighting device 100A_L functions as a mirror by reflecting (specular reflection) external light incident on the optical laminate 100A with the mirror layer 1, as shown in Figure 5 (light LRb in Figure 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 lit, and as a mirror when the light source LS is turned off. In other words, the lighting device 100A_L can switch 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). For this reason, the lighting device 100A_L can be said to be a design-oriented lighting device with a completely new application.

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

[0042] Furthermore, as a device that functions as both a lighting device and a mirror, it is conceivable to adopt a configuration in which the light source is placed on the back of a half-mirror. In this configuration, when the light source is lit, illumination is performed by the light that has passed through the half-mirror from the light emitted from the light source. Also, in this configuration, when the light source is turned off, the half-mirror functions as a mirror by reflecting external light. However, in this configuration, the light reflectivity of the half-mirror is low, so the mirrored image in mirror mode becomes dark. In addition, in lighting mode, a portion of the light emitted from the light source is reflected by the half-mirror, so the light utilization efficiency is low. In contrast, the lighting device 100A_L according to the embodiment of the present invention has the above-described configuration, which suppresses the darkening of the mirrored image in mirror mode and can increase the light utilization efficiency in lighting mode.

[0043] Furthermore, as a device that functions both as an illumination device and a mirror, it is conceivable to adopt a configuration in which an illumination device called a front light is placed in front of the mirror. However, in this configuration, the structure for extracting light formed on the light guide plate of the front light (for example, a dot-like pattern) may be visible, which may degrade the quality of the mirror image in mirror mode. In contrast, the illumination device 100A_L according to the embodiment of the present invention can avoid such problems.

[0044] [Examples of preferred configurations for the light guide layer and mirror layer] The light guide layer 10 can be formed from a known material with high transmittance to visible light. For example, the light guide layer 10 can be formed from an acrylic resin such as polymethyl methacrylate (PMMA), a polycarbonate (PC) resin, a cycloolefin resin, or glass (e.g., quartz glass, alkali-free glass, borosilicate glass). The refractive index n of the light guide layer 10... GP For example, it is between 1.40 and 1.80. Unless otherwise specified, the refractive index refers to the 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. For example, the thickness of the light guide layer 10 is between 0.05 mm and 50 mm.

[0045] The light guide layer 10, which has a light distribution control structure having multiple internal spaces IS, is manufactured, for example, by laminating a first film without a pattern and a second film with a desired fine pattern, or by bonding them together with an adhesive (including a pressure-sensitive adhesive).

[0046] For forming fine patterns on the second film, laser patterning, direct laser imaging, laser drilling, and laser or electron beam irradiation with or without a mask are used. Individual properties may also be imparted by printing, inkjet printing, screen printing, etc., and the material and refractive index may be modified. Micro / nano dispensing, dosing, direct "writing," discrete laser sintering, micro-electrical discharge machining (micro-EDM), or micro-machining, micro-forming, imprinting, embossing, and similar methods may also be used.

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

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

[0049] [Configuration with an anti-reflective layer] Referring to Figure 6, another lighting device 100B_L according to an embodiment of the present invention will be described. Figure 6 is a schematic cross-sectional view of the lighting device 100B_L. Below, the explanation will focus on the differences between the lighting device 100B_L and the lighting device 100A_L shown in Figure 1.

[0050] As shown in Figure 6, the optical laminate 100B of the lighting device 100B_L differs from the optical laminate 100A of the lighting device 100A_L in that it further includes an anti-reflective layer 20. The anti-reflective layer 20 is located on the third main surface 10b side of the light guide layer 10, that is, on the first main surface (light emission surface) side with respect to the light distribution control structure.

[0051] In the lighting device 100B_L, the anti-reflective layer 20 is provided, which suppresses surface reflection on the first main surface of the optical laminate 100B.

[0052] As the anti-reflective layer 20, for example, a multilayer laminate consisting of multiple thin films with different refractive indices can be used. Examples of materials for the thin films constituting the multilayer laminate include metal oxides, nitrides, fluorides, etc.

[0053] The anti-reflective layer 20 is preferably an alternating laminate of a high refractive index layer and a low refractive index layer. The refractive index of the high refractive index layer is, for example, 1.9 or higher, preferably 2.0 or higher. Examples of materials for the high refractive index layer include titanium oxide, niobium oxide, zirconium oxide, tantalum oxide, zinc oxide, indium oxide, indium tin oxide (ITO), antimond-doped tin oxide (ATO), etc. Among these, titanium oxide or niobium oxide is preferred. The refractive index of the low refractive index layer is, for example, 1.6 or lower, preferably 1.5 or lower. Examples of materials for the low refractive index layer include silicon oxide, titanium nitride, magnesium fluoride, barium fluoride, calcium fluoride, hafnium fluoride, lanthanum fluoride, etc. Among these, silicon oxide is preferred. In particular, it is preferable to alternately laminate a niobium oxide (Nb2O5) thin film as the high refractive index layer and a silicon oxide (SiO2) thin film as the low refractive index layer. In addition to the low refractive index layer and the high refractive index layer, a medium refractive index layer with a refractive index of about 1.6 to 1.9 may be provided.

[0054] The film thickness of the high-refractive-index layer and the low-refractive-index layer is approximately 5 nm to 200 nm, with a preference of approximately 15 nm to 150 nm. Depending on the refractive index and the lamination configuration, the film thickness of each layer should be designed to minimize the reflectivity of visible light.

[0055] The method for forming the thin film constituting the anti-reflective 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 uniform thickness. Among these, the sputtering method is preferred because it offers excellent uniformity of film thickness and facilitates the formation of a dense film. For example, the anti-reflective layer described in Japanese Patent Application Publication No. 2020-52221 can be suitably used. All disclosures of Japanese Patent Application Publication No. 2020-52221 are incorporated herein by reference.

[0056] [Construction with an antifouling layer] Referring to Figure 7, another lighting device 100C_L according to an embodiment of the present invention will be described. Figure 7 is a schematic cross-sectional view of the lighting device 100C_L. Below, the explanation will focus on the differences between the lighting device 100C_L and the lighting device 100A_L shown in Figure 1.

[0057] As shown in Figure 7, the optical laminate 100C of the lighting device 100C_L differs from the optical laminate 100A of the lighting device 100A_L in that it further comprises an antifouling layer 30. The antifouling layer 30 is water-repellent and / or oil-repellent (hydrophilic). The antifouling layer 30 is located 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 anti-fouling layer 30 is provided, which prevents dirt from adhering to the optical laminate 100C.

[0059] The composition of the antifouling layer 30 is appropriately selected depending on the application. The antifouling layer 30 can be formed using known materials. Silicone compounds or fluorine-containing compounds are preferred as materials constituting the antifouling layer 30. Among these, 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 rigidly parallelable main chain structure are particularly preferred. As structural units of the main chain skeleton of the perfluoropolyether, perfluoroalkylene oxides which may have branches with 1 to 4 carbon atoms are preferred, such as perfluoromethylene oxide (-CF2O-), perfluoroethylene oxide (-CF2CF2O-), perfluoropropylene oxide (-CF2CF2CF2O-), and perfluoroisopropylene oxide (-CF(CF3)CF2O-).

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

[0061] The method for forming the antifouling layer 30 can be a physical vapor deposition method such as vapor deposition or sputtering, a chemical vapor deposition method, a wet coating method such as reverse coating, die coating, or gravure coating, depending on the material. For example, the antifouling layer described in Japanese Patent Application Publication No. 2020-067582 can be suitably used. All disclosures of Japanese Patent Application Publication No. 2020-067582 are incorporated herein by reference.

[0062] An anti-reflective layer may be placed on the light guide layer 10 side of the anti-fouling layer 30 (between the anti-fouling layer 30 and the light guide layer 10).

[0063] [Configuration with a polarization-selective reflective layer] Referring to Figure 8, another lighting device 100D_L according to an embodiment of the present invention will be described. Figure 8 is a schematic cross-sectional view of the lighting device 100D_L. Below, the explanation will focus on the differences between the lighting device 100D_L and the lighting device 100A_L shown in Figure 1.

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

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

[0066] The applicant in the present application has proposed in International Publication No. 2021 / 200722 a privacy system that can prevent external viewing. This privacy system includes a display device and a partition that separates the space on which the display device provides a display from its surroundings. The display device has a first polarizing layer on the front surface of the display surface having a first absorption axis parallel to a first direction (e.g., one of the horizontal and vertical directions). The partition has a translucent portion that allows viewing into the aforementioned space. The translucent portion of the partition is located on the space side of a 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). With this configuration, it is possible to prevent the display by the display device from being viewed from the outside.

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

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

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

[0070] As shown in Figure 9, an anti-reflective layer 20 may be provided on the polarization-selective reflective layer 40 (on the first main surface side of the polarization-selective reflective layer 40).

[0071] [Other configurations with a polarization-selective reflective layer] Referring to Figure 10, another lighting device 100E_L according to an embodiment of the present invention will be described. Figure 10 is a schematic cross-sectional view of the lighting device 100E_L. Below, the explanation will focus on the differences between the lighting device 100E_L and the lighting device 100D_L shown in Figure 8.

[0072] As shown in Figure 10, the optical laminate 100E of the lighting device 100E_L differs from the optical laminate 100D of the lighting device 100D_L in that it further includes a direction conversion layer 60. The direction conversion layer 60 is provided on the third main surface 10b side of the light guide layer 10.

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

[0074] Figure 11 shows a specific example of the configuration of the direction conversion layer 60 on which the light distribution control structure is formed. In the example shown in Figure 11, the direction conversion layer 60 is composed of a shaping film 62 having a fifth main surface 62a with a plurality of recesses 62r, and an adhesive layer 64 positioned on the fifth main surface 62a side of the shaping film 62. The adhesive layer 64 is located between the shaping film 62 and the light guide layer 10, and the light guide layer 10 and the shaping film 62 are bonded together by the adhesive layer 64. Multiple internal spaces IS are defined by the plurality of recesses 62r of the shaping film 62 and the adhesive layer 64.

[0075] The shaping film 62 for forming the internal space IS can be manufactured, for example, by the method described in Japanese Patent Publication No. 2013-524288. Specifically, for example, the shaping film 62A can be manufactured by coating the surface of a polymethyl methacrylate (PMMA) film with lacquer (for example, FineCure RM-64 manufactured by Sanyo Chemical Industries, Ltd.), embossing an optical pattern onto the film surface containing the lacquer, and then curing the lacquer.

[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, more preferably 1.47 to 1.58. Furthermore, the refractive index of the adhesive layer 64 is preferably close to that of the light guide layer 10 or the shaping film 62, and the absolute value of the difference in refractive index is preferably 0.2 or less.

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

[0078] Preferably, the adhesive layer 64 can adhere to the shaping film 62 without filling the recesses 62r on the surface. Suitable adhesives for forming the adhesive layer 64 include those described in the present applicant's International Publication No. 2021 / 167090, International Publication No. 2021 / 167091, or International Application PCT / JP2022 / 004554. All disclosures of these applications are incorporated herein by reference. In particular, the polyester-based adhesive described in International Application PCT / JP2022 / 004554 is preferred.

[0079] Although not shown in the diagram, the shaping film 62 and the polarization selective reflective layer 40 can be bonded together by an adhesive layer.

[0080] Furthermore, Figure 10 illustrates a configuration in which the direction changing layer 60 is provided on the third main surface 10b side of the light guide layer 10, but the arrangement of the direction changing layer 60 is not limited to this. Figure 12 shows another example of the arrangement of the direction changing layer 60. In the example shown in Figure 12, the direction changing layer 60 is provided 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).

[0081] [Configuration includes a quarter-wave plate in addition to a polarization-selective reflective layer.] Referring to Figure 13, another lighting device 100F_L according to an embodiment of the present invention will be described. Figure 13 is a schematic cross-sectional view of the lighting device 100F_L. Below, the explanation will focus on the differences between the lighting device 100F_L and the lighting device 100E_L shown in Figure 10.

[0082] As shown in Figure 13, the optical laminate 100F of the illumination device 100F_L differs from the optical laminate 100E of the illumination device 100E_L in that it further includes a quarter-wave plate 70. The quarter-wave plate 70 is positioned 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, the quarter-wave plate 70 described above is provided, and the light distribution control structure allows the light reflected by the polarization-selective reflective layer 40 (i.e., light that could not be transmitted through the polarization-selective reflective layer 40) from the light directed toward the first main surface to be polarized in a way that allows it to be transmitted through the polarization-selective reflective layer 40 (to a polarization direction perpendicular to the original polarization direction), thereby increasing the efficiency of light utilization.

[0084] Various known quarter-wave plates can be used as the quarter-wave plate 70. Figure 13 shows an example where the quarter-wave plate 70 is positioned on the fourth main surface 10c side of the light guide layer 10, but the arrangement of the quarter-wave plate 70 is not limited to this. Figure 14 shows another example of the arrangement of the quarter-wave plate 70. In the example shown in Figure 14, the quarter-wave plate 70 is positioned between the direction conversion layer 60 and the polarization selective reflection layer 40. The arrangement exemplified in Figure 13 and the arrangement exemplified in Figure 14 are optically equivalent and function similarly.

[0085] [Other examples of light distribution control structures] In the explanation so far, we have exemplified a light distribution control structure that directs a portion of the light propagating within the light guide layer 10 toward the first main 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 main surface side.

[0086] For example, the light distribution control structure (first light distribution control structure) formed within 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 side by internal total internal reflection, as shown in the lighting device 100A_L in Figure 15. The cross-sectional shape of these internal spaces IS is, for example, a triangle with its apex angle on the second main surface side of the optical laminate 100A (the -Z direction in Figure 15).

[0087] Furthermore, the light distribution control structure (second light distribution control structure) formed in the direction conversion 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 side by internal total internal reflection, as shown in the lighting device 100E_L in Figure 16. The cross-sectional shape of these internal spaces IS is, for example, a triangle with its apex angle on the second main surface side of the optical laminate 100A (the -Z direction in Figure 16).

[0088] With this light distribution control structure, light directed towards the second main surface is reflected by the mirror layer 1 and directed towards the first main surface, where it exits. Therefore, even when the light distribution control structure is configured to direct a portion of the light propagating within the light guide layer 10 towards the second main surface, illumination can be performed effectively.

[0089] [Other configurations] Referring to Figure 17, another lighting device 100G_L according to an embodiment of the present invention will be described. Figure 17 is a schematic cross-sectional view of the lighting device 100G_L. Below, the explanation will focus on the differences between the lighting device 100G_L and the lighting device 100E_L shown in Figure 10.

[0090] As shown in Figure 17, the optical laminate 100G of the lighting device 100G_L further has an optical coupling layer 80 provided between the light guide layer 10 and the direction conversion layer 60. The optical coupling layer 80 has a refractive index n of the light guide layer 10. GP A refractive index n smaller than C It has multiple low refractive index regions 80a. Each low refractive index region 80a is formed in the shape of a dot, for example, with a size of 1 μm to 1000 μm.

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

[0092] As shown in Figure 18, the polarization selective reflective layer 40 of the lighting device 100G_L may be omitted. The effect of providing the optical coupling layer 80 can be obtained even in the configuration in which the polarization selective reflective layer 40 is omitted, as shown in Figure 18. The direction conversion layer 60 may also be provided 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). Even in the configuration in which the direction conversion layer 60 is provided on the fourth main 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 conversion layer 60.

[0093] Refractive index n in the low refractive index region 80a C The refractive index n of the light guide layer 10 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 in the low refractive index region 80a C The difference between the two values ​​is preferably 0.20 or more, more preferably 0.23 or more, and even more preferably 0.25 or more. Refractive index n C The low refractive index region 80a with a refractive index of 1.30 or less may be, for example, a porous region having an internal void structure. The thickness of the low refractive index region 80a is, for example, 0.3 μm or more and 5 μm or less.

[0094] If the low refractive index region 80a is a porous region, its porosity is preferably 35 volume% or more, more preferably 38 volume% or more, and particularly preferably 40 volume% 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 volume% or less, and preferably 75 volume% 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. All of the disclosures in International Publication No. 2019 / 146628 are incorporated herein by reference. Specifically, the low refractive index region 80a having a void structure may include substantially spherical particles such as silica particles, silica particles with micropores, silica hollow nanoparticles, fibrous particles such as cellulose nanofibers, alumina nanofibers, silica nanofibers, and plate-like particles such as nanoclay composed of bentonite. The low refractive index region 80a having a void structure may be a porous body in which particles (e.g., microporous particles) are directly chemically bonded to each other. Furthermore, at least some 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 or equal to the mass of the particles) of a binder component. The porosity and refractive index n of the low refractive index region 80a C This can be adjusted by the particle size, particle size distribution, etc., of the particles constituting the low refractive index region 80a.

[0096] As a method for obtaining the low refractive index region 80a having a void structure, for example, the methods described in JP-A-2010-189212, JP-A-2008-040171, JP-A-2006-011175, International Publication No. 2004 / 113966, and their reference documents can be mentioned. The entire disclosure contents of JP-A-2010-189212, JP-A-2008-040171, JP-A-2006-011175, and International Publication No. 2004 / 113966 are incorporated herein by reference.

[0097] As the low refractive index region 80a having a void structure, a silica porous body can be preferably used. The silica porous body is produced, for example, by the following methods. A method of hydrolyzing and polycondensing a silicon compound; at least any one of hydrolyzable silanes and / or silsesquioxanes, and their partial hydrolyzates and dehydration condensates, a method using porous particles and / or hollow fine particles, and a method of generating an aerogel layer using the springback phenomenon, a method using a pulverized gel obtained by pulverizing a gel-like silicon compound obtained by the sol-gel method and chemically bonding fine pore particles, which are the obtained pulverized bodies, with a catalyst or the like, and the like can be mentioned. However, the low refractive index region 80a is not limited to the silica porous body, and the production method is not limited to the exemplified production methods, and it may be produced by any production method. In addition, silsesquioxane is a silicon compound having (RSiO 1.5 , where R is a hydrocarbon group) as a basic structural unit, and although it is strictly different from silica having SiO2 as a basic structural unit, it is common with silica in that it has a network structure crosslinked by a siloxane bond. Therefore, here, a porous body containing silsesquioxane as a basic structural unit is also referred to as a silica porous body or a silica-based porous body.

[0098] A porous silica material may be composed of microporous particles of a gel-like silicon compound that are bonded together. Examples of microporous particles of a gel-like silicon compound include pulverized gel-like silicon compounds. A porous silica material can be formed, for example, by coating a substrate with a coating solution containing pulverized gel-like silicon compounds. The pulverized gel-like silicon compounds can be chemically bonded (e.g., siloxane bonds) by means of a catalyst, light irradiation, heating, etc.

[0099] Referring to Figure 19, another lighting device 100H_L according to an embodiment of the present invention will be described. Figure 19 is a schematic cross-sectional view of the lighting device 100H_L. Below, the explanation will focus on the differences between the lighting device 100H_L and the lighting device 100G_L shown in Figure 18.

[0100] As shown in Figure 19, the optical laminate 100H of the lighting device 100H_L has a first region R1 in which a light distribution control structure exists (i.e., an internal space IS is formed) and a second region R2 in which a light distribution control structure does not exist (i.e., an internal space IS is not formed). The first region R1 and the second region R2 are arranged to define a predetermined pattern when viewed from a plan view from the direction normal to the first main surface. Here, "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 it may have an optical coupling layer 80.

[0101] Figure 20 shows an example of the arrangement of the first region R1 and the second region R2. Figure 20 shows the lighting device 100H_L in the illuminated state.

[0102] As shown in Figure 20, the first region R1, where the light distribution control structure exists, is the region that emits light when the light is on (light-emitting region), and the second region R2, where the light distribution control structure does not exist, is the region that does not emit light substantially when the light is on (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 illustrated in Figure 20.

[0103] Thus, in the lighting device 100H_L, the first region R1, where a light distribution control structure exists, and the second region R2, where a light distribution control structure does not exist, are arranged to define a predetermined pattern, thereby enabling the emission of light in a predetermined pattern during the lighting mode. As a result, lighting (light emission) that is rich in design and entertainment value can be realized.

[0104] Furthermore, in the example shown in Figure 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 under normal circumstances and as an emergency exit sign indicating the direction of evacuation in illumination mode. Constantly displaying emergency exit signs (exit signs) may detract from the aesthetics of facilities and buildings, but by using the lighting device 100H_L in this way, such a deterioration in aesthetics can be prevented. Thus, depending on the design, the lighting device 100H_L can also be used for more practical purposes, and since it can function as a mirror under normal circumstances, it can prevent damage to aesthetics even when used for practical purposes.

[0105] Referring to Figure 21, another lighting device 100I_L according to an embodiment of the present invention will be described. Figure 21 is a schematic cross-sectional view of the lighting device 100I_L. Below, the explanation will focus on the differences between the lighting device 100I_L and the lighting device 100G_L shown in Figure 18.

[0106] As shown in Figure 21, the optical laminate 100I of the illumination device 100I_L has a first region R1' in which the optical coupling layer 80 exists and a second region R2' in which the optical coupling layer 80 does not exist. The first region R1' and the second region R2' are arranged to define a predetermined pattern when viewed from a plan view from the direction normal to the first main surface.

[0107] In the first region R1' where the optical coupling layer 80 exists (i.e., the low refractive index region 80a is formed), light propagating within the light guide layer 10 has difficulty reaching the light distribution control structure (internal space IS) due to total internal reflection in the optical coupling layer 80. Therefore, the first region R1' where the optical coupling layer 80 exists is a region that emits light at a relatively low brightness (or virtually no light) when lit (low brightness emission region). In contrast, the second region R2' where the optical coupling layer 80 does not exist (i.e., the low refractive index region 80a is not formed) is a region that emits light at a relatively high brightness when lit (high brightness emission region).

[0108] Thus, in the lighting device 100I_L, the first region R1' where the optical coupling layer 80 exists and the second region R2' where the optical coupling layer 80 does not exist are arranged to define a predetermined pattern, so that the lighting device can emit light in a way that allows the predetermined pattern to be visible in the lighting mode. Therefore, it is possible to realize lighting (light emission) that is rich in design and entertainment value.

[0109] Suitable methods for selectively forming the low refractive index region 80a in the first region R1' include coating or printing. When using the coating method, coating can be performed using a mask having a predetermined pattern. As for the printing method, plate-based printing methods such as gravure printing or plateless printing methods such as inkjet printing may be used. [Industrial applicability]

[0110] According to embodiments of the present invention, it is possible to provide a lighting device that is highly aesthetically pleasing or entertaining, and an optical laminate suitably used in such a lighting device. The lighting device according to embodiments of the present invention is a device for entirely new applications that is used by switching between a lighting mode and a mirror mode, and can be used, for example, as a building component. [Explanation of Symbols]

[0111] 1. Mirror layer 10 Light guide layer 10a Light-receiving side of the light guide layer 10b Third main surface of the light guide layer 10c Fourth main surface of the light guide layer 20 Anti-reflection layer 30 Anti-fouling layer 40 Polarization Selective Reflective Layer 60 Directional Conversion Layer 62 Shaping film 62r Recess of the shaping film 64 Adhesive layer 70 1 / 4 wave plate 80 Optical coupling layer 80a Low refractive index region 100A, 100B, 100C, 100D, 100E, 100F Optical Stacks 100G, 100H, 100I Optical Stacks 100A_L, 100B_L, 100C_L lighting equipment 100D_L, 100E_L, 100F_L lighting equipment 100G_L, 100H_L, 100I_L lighting equipment IS interior space ISa First Incline ISb 2nd slope LS light source R1, R1' 1st region R2, R2' second area

Claims

1. An optical laminate used in a lighting device that can switch between a lighting mode in which it functions as a lighting device and a mirror mode in which it functions as a mirror, having a first main surface and a second main surface opposite to the first main surface, A light-receiving section that receives light emitted from a light source, a light-guiding layer having a third main surface on the first main surface side and a fourth main surface on the second main surface side, A light-reflective mirror layer is disposed on the fourth main surface side of the light guide layer, A light distribution control structure having multiple internal spaces, wherein the multiple internal spaces form interfaces that direct a portion of the light propagating within the light guide layer toward the first main surface side or the second main surface side by total internal reflection, An optical laminate having [a certain characteristic].

2. The optical laminate according to claim 1, further comprising a polarization selective reflective layer disposed on the first main 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 reflective layer and the mirror layer.

4. The optical laminate according to any one of claims 1 to 3, further comprising an anti-reflective layer disposed on the first main 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 a water-repellent and / or oil-repellent antifouling layer as the outermost layer on the first main 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 within 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 main surface side or the fourth main surface side of the light guide layer.

8. An optical laminate having a first principal surface and a second principal surface opposite to the first principal surface, A light-receiving section that receives light emitted from a light source, a light-guiding layer having a third main surface on the first main surface side and a fourth main surface on the second main surface side, A light-reflective mirror layer is disposed on the fourth main surface side of the light guide layer, A light distribution control structure having multiple internal spaces, wherein the multiple internal spaces form interfaces that direct a portion of the light propagating within the light guide layer toward the first main surface side or the second main surface side by total internal reflection, It has, 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, The optical laminate further comprises an optical coupling layer provided between the light guide layer and the direction conversion layer, The optical coupling layer is an optical laminate having 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 from a plane direction normal to the first main surface, the first region where the light distribution control structure exists and the second region where the light distribution control structure does not exist are arranged to define a predetermined pattern.

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

11. An optical laminate according to any one of claims 1 to 3, A light source that emits light toward the light receiving unit, A lighting device equipped with the following features.

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