Optical member and lighting device

Abstract

The optical member (100) includes a light guide member (110) and at least one cover member (200F, 200R), and is configured to emit light toward a front surface side, and the light guide member includes a light guide layer (10) having a light receiving side surface that receives light emitted from a light source (LS), and a light distribution control structure (14A) that enables a portion of light propagating through the light guide layer to face at least the front surface side. At least one of the cover members includes a first cover member (200F) disposed on the front surface side of the light guide member or a second cover member (200R) disposed on the back surface side opposite to the front surface side of the light guide member. The optical member (100) is configured so that more than 50% of light incident into the light guide layer is emitted from the front surface side of the light guide member.

Description

Technical Field

[0001] The present invention relates to an optical member having a light guide layer, and a lighting device having a light source and the optical member. Background Art

[0002] In recent years, various lighting devices using LED elements as light sources have been developed, including sheet-shaped (including plate-shaped and film-shaped) lighting devices having a light source and a light guide layer.

[0003] For example, Patent Document 1 discloses a lighting device provided with a light guide plate that is provided in a skylight and that allows sunlight to pass therethrough.

[0004] In addition, a lighting device in which a light guide layer is disposed between two cover members is disclosed in Patent Document 2. By making the reflectance of the two cover members different, the light emission efficiency to one side can be improved.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2012-49050

[0008] Patent Document 2: Japanese Patent Application Publication No. 2014-10919 Summary of the invention

[0009] Problems to be solved by the invention

[0010] However, conventional sheet-shaped lighting devices having a light source and a light guide layer each have various problems and are limited in the scenarios in which they can be applied.

[0011] For example, the lighting device described in Patent Document 1 can be used for skylights, but it is difficult to install on windows or walls. In addition, the light utilization efficiency is low, and / or the lighting light is diffuse light. If used for windows, there are problems such as white turbidity (large haze value). In addition, the lighting device described in Patent Document 2 uses the reflection of the cover member, so there is a problem that the utilization efficiency of the light transmitted through the lighting device is reduced.

[0012] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a lighting device that can be used in various scenes such as windows and walls, and an optical member that can be used for such a lighting device.

[0013] Solutions to the problem

[0014] According to an embodiment of the present invention, the solution methods described in the following items are provided.

[0015] [Project 1]

[0016] An optical member includes a light guide member and at least one cover member, and is configured so that light is emitted toward a front side.

[0017] The light guide member includes: a light guide layer having a light receiving side surface for receiving light emitted from the light source, and a light distribution control structure for allowing a portion of the light propagating in the light guide layer to be directed toward at least the front side.

[0018] The at least one cover member includes a first cover member disposed on the front side of the light guide member or a second cover member disposed on the back side of the light guide member opposite to the front side.

[0019] The optical member is configured such that more than 50% of the light incident on the light guide layer is emitted from the front surface side of the light guide member.

[0020] [Project 2]

[0021] The optical component according to item 1, wherein

[0022] The reflectance of the first cover member and the second cover member with respect to visible light vertically incident from the light guide member side is 25% or less.

[0023] [Item 3]

[0024] The optical component according to item 1 or 2, wherein:

[0025] The first cover member or the second cover member includes a glass plate.

[0026] [Item 4]

[0027] The optical component according to item 3, wherein:

[0028] The first cover member further includes an antireflection layer provided on at least one main surface of the glass plate.

[0029] [Item 5]

[0030] The optical member according to any one of items 1 to 4, wherein

[0031] When the light having the highest intensity in the light distribution of the light emitted from the light guide member toward the front side is set as the first principal light, and the light having the highest intensity in the light distribution of the light emitted from the light guide member toward the back side is set as the second principal light,

[0032] A polar angle θ1 of the first principal ray with respect to the normal line of the light guide layer is smaller than a polar angle θ2 of the second principal ray with respect to the normal line of the light guide layer.

[0033] [Item 6]

[0034] The optical component according to item 5, wherein

[0035] The polar angle θ1 is greater than or equal to 0° and less than 40°, and the polar angle θ2 is greater than or equal to 30° and less than 70°.

[0036] [Item 7]

[0037] The optical member according to any one of items 1 to 6, wherein

[0038] The light guide member is disposed to be isolated from the at least one cover member via a gas layer.

[0039] [Item 8]

[0040] The optical member according to any one of items 1 to 7, wherein

[0041] The light guide layer is formed of acrylic resin.

[0042] [Item 9]

[0043] The optical member according to any one of items 1 to 8, wherein

[0044] The light distribution control structure includes a plurality of internal spaces, and the plurality of internal spaces include a front inclined surface that allows light to be directed toward the front side by total internal reflection.

[0045] [Item 10]

[0046] The optical member according to any one of items 1 to 9, wherein

[0047] The light distribution control structure is formed on a direction changing layer, and the direction changing layer is disposed on the front side or the back side of the light guiding layer.

[0048] [Item 11]

[0049] The optical member according to any one of items 1 to 10, wherein

[0050] The light guide member has a visible light transmittance of 60% or more and a haze value of less than 10%.

[0051] [Item 12]

[0052] A lighting device, comprising:

[0053] The optical member according to any one of items 1 to 11, and

[0054] A light source is arranged so as to emit light toward the light receiving surface of the optical member.

[0055] Effects of the Invention

[0056] According to the embodiments of the present invention, it is possible to provide a lighting device that can be used in various scenes such as windows and walls, and an optical member that can be used for such a lighting device. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 It is a schematic cross-sectional view of a lighting device 1000 according to an embodiment of the present invention.

[0058] Figure 2 1 is a schematic plan view of the light guide member 110 included in the lighting device 1000 .

[0059] Figure 3A 14A is a schematic cross-sectional view of an internal space 14A that the light guide member 110 may have.

[0060] Figure 3B 14A is a schematic top view of the internal space 14A.

[0061] Figure 3C 1 is a schematic plan view showing deformation of the internal space 14A.

[0062] Figure 4 It is a schematic cross-sectional view of a light guide member 110A included in a lighting device according to another embodiment of the present invention.

[0063] Figure 5 It is a schematic cross-sectional view of a light guide member 110B included in a lighting device according to another embodiment of the present invention.

[0064] Figure 6 It is a schematic partial perspective view of an optical member 300A according to an embodiment of the present invention.

[0065] Figure 7 It is a schematic partial perspective view of an optical member 300B according to an embodiment of the present invention.

[0066] Explanation of symbols

[0067] 10: Light guide layer

[0068] 14A: Inner Space

[0069] 100: Optical components

[0070] 110: Light guide component

[0071] 200F: 1st cover member

[0072] 200R: Second cover member

[0073] 1000: Lighting device DETAILED DESCRIPTION

[0074] Hereinafter, an optical member and a lighting device according to an embodiment of the present invention will be described with reference to the drawings. It should be noted that the optical member and the lighting device according to the embodiment of the present invention are not limited to the examples described below.

[0075] Figure 1 A schematic cross-sectional view of a lighting device 1000 according to an embodiment of the present invention is shown in FIG. The dashed arrows in the figure represent examples of light rays.

[0076] The lighting device 1000 includes a light source LS and an optical member 100. The optical member 100 includes a light guide member 110, a first cover member 200F, and a second cover member 200R. The optical member is configured to direct light toward the front side ( Figure 1 It is composed of the emission method of (in the center-Z direction).

[0077] The light-guiding component 110 includes: a light-guiding layer 10 having a light-receiving side surface for receiving light emitted from a light source LS, and a light distribution control structure for allowing at least a portion of light propagating in the light-guiding layer 10 (in the y direction) to be directed toward the front side. The light distribution control structure exemplified here has a plurality of internal spaces 14A, and the plurality of internal spaces 14A have a front inclined surface ISa for directing light toward the front side by total internal reflection (TIR). The "front" of the "front inclined surface" possessed by the internal space refers to a surface located on the light-receiving side surface side (close to the light-receiving side surface) in the inclined side surface possessed by the internal space. It should be noted that the inclined surface located on the opposite side to the light-receiving side surface (away from the light-receiving side surface) in the inclined side surface possessed by the internal space is referred to as a "rear inclined surface".

[0078] The light guide member 110 has a light distribution control structure in the light guide layer 10, but is not limited thereto. As exemplified below, the light guide member may further have a direction changing layer (sometimes referred to as a "light extraction layer") and the direction changing layer may have a light distribution control structure. The light guide member 110 is configured so that more than 50% of the light incident into the light guide layer 10 is emitted from the front side of the light guide member 110.

[0079] The optical member 100 includes a first cover member 200F disposed on the front side of the light guide member 110 and a second cover member 200R disposed on the back side opposite to the front side of the light guide member 110. One of the first cover member 200F and the second cover member 200R may be omitted. It is sufficient to dispose the first cover member 200F or the second cover member 200R on the side to be protected of the light guide member 110 according to the environment in which the lighting device 1000 is used.

[0080] The first cover member 200F and the second cover member 200R are arranged to be isolated from the light guide member 110 via a gas layer GL. The gas layer GL may be, for example, an air layer. For example, a closed space may be formed between the first cover member 200F and the light guide member 110, and / or a closed space may be formed between the second cover member 200R and the light guide member 110, as in multi-layer glass having high heat insulation performance, and the gas layer GL may be formed using, for example, argon gas. In the case of multi-layer glass, a spacer including a desiccant may be further arranged in contact with the gas layer GL.

[0081] If a gas layer GL is provided, total reflection at the interface between the light guide member 110 and the gas layer GL can be utilized to allow light to propagate efficiently within the light guide member 110. A low refractive index layer (for example, a refractive index of less than 1.30) may also be provided instead of the gas layer GL. It should be noted that the light guide member 110 and the first cover member 200F and / or the second cover member 200R may be bonded together, for example, by an adhesive layer. At this time, it is preferred that no optical interface is formed between the light guide member 110, the adhesive layer, the first cover member 200F and / or the second cover member 200R.

[0082] The reflectivity of the first cover member 200F and the second cover member 200R to visible light vertically incident from the light guide member 110 side is preferably 25% or less. As the first cover member 200F and / or the second cover member 200R, for example, Low-E glass can be used. Low-E (low-emissivity) glass has a Low-E metal (for example, silver) film (and a metal oxide film) on the surface of a glass plate. The Low-E metal is arranged on the light guide member 110 side of the glass plate.

[0083] The first cover member 200F and / or the second cover member 200R may include a glass plate. The first cover member 200F and / or the second cover member 200R may include a plastic plate with high visible light transmittance. As plastic, for example, polymethyl methacrylate (PMMA), polycarbonate (PC), polyvinyl chloride (PVC), polyethylene terephthalate (PET) can be used. It should be noted that, compared with plastic plates, glass plates have the characteristics of high hardness and high flame retardancy. Therefore, when used as a building component, a glass plate is preferably used. On the other hand, when used as a window of a display cabinet, etc., a lightweight plastic plate is preferably used. The thickness of the glass plate and the plastic plate is not particularly limited and can be appropriately set according to the purpose. The thickness of the glass plate is, for example, greater than 1 mm and less than 15 mm. The thickness of the plastic plate is, for example, greater than 1 mm and less than 15 mm.

[0084] In applications requiring heat insulation or heat insulation performance, the above-mentioned Low-E glass can be appropriately used. Preferably, the first cover member 200F and the second cover member 200R have high visible light transmittance and low visible light reflectance. The visible light reflectance of the first cover member 200F and the second cover member 200R is preferably less than 15%, more preferably less than 10%, further preferably less than 5%, and further preferably less than 3%. The first cover member 200F and / or the second cover member 200R having such a low visible light reflectance can be obtained by providing an anti-reflection film on at least one main surface of a glass plate or a plastic plate. As an anti-reflection film, various known anti-reflection films can be used. For example, as described in the experimental example, the low-reflection film Luclear II made by Sangetsu Co., Ltd. can be pasted on at least one main surface of a glass plate or a plastic plate. For example, an anti-reflection film can be provided on at least one main surface of the two main surfaces of the first cover member 200F on the light emitting side.

[0085] like Figure 1 As shown, the lighting device 1000 emits light LRf toward the front side and emits light LRr toward the back side. The light distribution of the light emitted toward the front side is different from the light distribution of the light emitted toward the back side. The light distribution can be controlled, for example, by adjusting the inclination angle θa of the front inclined surface ISa and / or the inclination angle θb of the rear inclined surface ISb.

[0086] It should be noted that the light distribution of a lighting device refers to the distribution of luminous intensity (intensity) relative to an angle, and is independent of the wavelength of light emitted from the lighting device. The light distribution of a lighting device can be measured, for example, by a method based on JIS C8105-5. For example, the light distribution is characterized by the direction of the light with the highest luminous intensity (intensity) in the light distribution (hereinafter referred to as the "principal light").

[0087] When the light with the highest intensity in the light distribution of the light emitted from the light guide member 110 to the front side is set as the first principal light, and the light with the highest intensity in the light distribution of the light emitted from the light guide member 110 to the back side is set as the second principal light, the polar angle θ1 of the first principal light relative to the normal of the light guide layer 10 is smaller than the polar angle θ2 of the second principal light relative to the normal of the light guide layer 10. For example, the polar angle θ1 is greater than 0° and less than 40°, and the polar angle θ2 is greater than 30° and less than 70° (for example, see Japanese Patent Application No. 2021-096846). The disclosure of Japanese Patent Application No. 2021-096846 is incorporated herein by reference in its entirety. By making the light guide member 110 have such a light distribution, the lighting device 1000 can emit more light to the front side than to the back side. That is, the light guide member 110 is configured so that more than 50% of the light incident into the light guide layer 10 is emitted from the front side of the light guide member 110. In addition, light with high directivity can be emitted toward the front side.

[0088] The light guide component 110 has, for example, a visible light transmittance of 60% or more. In addition, the light guide component 110 has, for example, a haze value of less than 10%. The visible light transmittance of the light guide component 110 is preferably 70% or more, more preferably 80% or more. The haze value of the light guide component 110 is preferably 5% or less. Here, light with a wavelength of 380 nm or more and 780 nm or less is regarded as visible light. The visible light transmittance and the haze value can be measured, for example, using a haze meter (Murakami Color Technology Laboratory: trade name HM-150).

[0089] The light source LS is, for example, an LED device, and a plurality of LED devices may be arranged and used. In addition, a coupling optical system for efficiently guiding light emitted from the light source LS to the light guide layer 10 may be provided between the light source LS and the light guide layer 10 .

[0090] The light distribution can be controlled by adjusting the cross-sectional shape, planar shape, size, configuration density, and distribution of the internal space 14A. Figure 3A As described above, the inclination angle θa of the front inclined surface ISa is, for example, greater than 10° and less than 70°. In addition, the inclination angle θb of the rear inclined surface ISb is, for example, greater than 50° and less than 100°. The cross-sectional shape of the internal space 14A is a triangle as shown in the example, but is not limited to this, and may also be a trapezoid or the like independently.

[0091] For the multiple internal spaces 14A as the light distribution control structure, when the light guide layer 10 is observed from the normal direction of the main surface, the proportion of the area of ​​the multiple internal spaces 14A in the area of ​​the light guide layer 10 (occupancy rate) is preferably greater than 1% and less than 80%, and the upper limit is more preferably less than 50%, and further preferably less than 45%. In order to obtain high transmittance and / or low haze value, it is preferably less than 30%, more preferably less than 10%, and further preferably less than 5%. For example, when the occupancy rate of the internal space is 50%, a haze value of 30% can be obtained. It should be noted that the occupancy rate of the internal space 14A can be uniform, or the occupancy rate can be increased with increasing distance, so that even if the distance relative to the light source LS increases, the brightness will not decrease. In order to perform mass production by roll-to-roll or roll-to-sheet method, the occupancy rate of the internal space 14A is preferably uniform.

[0092] Next, refer to Figure 2 An example of the planar shape and arrangement of the internal space 14A will be described. Figure 2 1 is a schematic top view of the light guide member 110. Figure 3A , Figure 3B and Figure 3CThe shape of the internal space 14A will be described. Figure 3A is a schematic cross-sectional view of the internal space 14A, Figure 3B is a schematic top view of the internal space 14A, Figure 3C 1 is a schematic plan view showing deformation of the internal space 14A.

[0093] like Figure 2 As shown, the plurality of internal spaces 14A are discretely arranged in the light guiding direction (y direction) and the direction (x direction) perpendicular to the light guiding direction of the light guiding layer 10. The size of the internal space 14A (length L, width W: see Figure 3A , Figure 3B ), for example, the length L is preferably 10 μm or more and 500 μm or less, and the width W is preferably 1 μm or more and 100 μm or less. In addition, from the viewpoint of light extraction efficiency, the height H (see Figure 3A ) is preferably greater than or equal to 1 μm and less than or equal to 100 μm.

[0094] Here, an example is shown in which a plurality of internal spaces 14A are discretely arranged in the light guiding direction (y direction) of the light guiding layer 10 and in a direction (x direction) perpendicular to the light guiding direction, but the present invention is not limited thereto, and a plurality of internal spaces 14A may be discretely arranged in the light guiding direction (y direction) of the light guiding layer 10 and in a direction intersecting the light guiding direction. The discrete configuration of the internal spaces 14A may be appropriately set according to the shape of the light guiding layer 10, the required light distribution, and the like. It should be noted that, in the light guiding layer 10, light propagates in various directions, but the y direction is referred to as the light guiding direction, and light having a component in the y direction (not zero) is referred to as propagating in the y direction. In addition, the same setting is applied to other directions. That is, light propagating in the -y direction includes all light having a component in the -y direction (not zero).

[0095] The plurality of internal spaces 14A may be discretely arranged, for example, in the light guiding direction and in a direction intersecting the light guiding direction. The discrete arrangement may have periodicity (regularity) in at least one direction, or may have no regularity. However, from the perspective of mass production, it is preferred that the plurality of internal spaces 14A be uniformly arranged. For example, Figure 2 In the example shown, a plurality of internal spaces 14A having substantially the same shape and curved surfaces convex in the same direction are discretely and periodically arranged in the entire region in the light guiding direction (y direction) and the direction orthogonal to the light guiding direction (x direction) of the light guiding layer 10. In this case, the pitch Px is preferably, for example, greater than 10 μm and less than 500 μm, and the pitch Py is preferably, for example, greater than 10 μm and less than 500 μm. Figure 2 In the example shown, there are further internal spaces arranged so as to be shifted by half the pitch in the y direction and the x direction.

[0096] like Figure 2 As shown, when observed from the normal direction of the main surface of the light guide layer 10, the front inclined surface ISa forms a curved surface convex toward the light source LS. The light source LS is, for example, an LED device, and a plurality of LED devices are arranged in the x direction. The light emitted from the plurality of LED devices has divergence with respect to the y direction. Therefore, when the front inclined surface ISa has a curved surface convex toward the light source LS, the front inclined surface ISa acts on the light more uniformly. It should be noted that when a coupling optical system is provided between the light source LS and the light receiving side of the light guide component 110 so that light with high parallelism (light with small divergence with respect to the y direction) is incident, the front inclined surface ISa can be parallel to the x direction. In addition, the discrete internal space 14A may be replaced by an internal space such as a groove extending in the x direction (e.g., a triangular prism).

[0097] like Figure 3A As shown, the cross-sectional shape of the internal space 14A is, for example, a triangle. The inclination angle θa of the front inclined surface ISa on the light source LS side is, for example, greater than 10° and less than 70°. If the inclination angle θa is less than 10°, the controllability of the light distribution is sometimes reduced, and the light extraction efficiency is also reduced. On the other hand, if the inclination angle θa exceeds 70°, sometimes, for example, manufacturing becomes difficult. In addition, the inclination angle θb of the rear inclined surface ISb is, for example, greater than 50° and less than 100°. If the inclination angle θb is less than 50°, stray light may sometimes be generated in an unintended direction. On the other hand, if the inclination angle θb exceeds 100°, sometimes, for example, manufacturing becomes difficult. As Figure 3B and Figure 3C As shown, the length L of the internal space 14A is preferably 10 μm or more and 500 μm or less, and the width W is preferably 1 μm or more and 100 μm or less. The length L is, for example, at least twice the width W. The height H (see Figure 3A ) is preferably 1 μm or more and 100 μm or less. Figure 3B The concave portion of the plane shape shown is formed with a processing accuracy having Figure 3C In this case, the planar shape of the internal space can also be characterized by the length L and the width W. When observed from the normal direction of the main surface of the light guide layer 10, the shape of the curved surface of the front inclined surface ISa that is convex toward the light source LS can be represented by a quartic curve, for example. The internal space 14A can be composed of a shaped film having a concave portion on the surface and an adhesive layer, for example, as described later.

[0098] Next, refer to Figure 4 and Figure 5 A lighting device according to another embodiment of the present invention will be described. In the lighting device exemplified below, the light distribution control structure is formed on the direction changing layer, and the direction changing layer is disposed on the front side or the back side of the light guide layer.

[0099] Figure 4 A schematic cross-sectional view of a light guide member 110A included in a lighting device according to another embodiment of the present invention is shown in FIG. Figure 4 In FIG, a light source LS is also shown.

[0100] The light-guiding member 110A includes: a light-guiding layer 10 having a light-receiving side surface for receiving light emitted from a light source LS, and a direction-changing layer 60A arranged on the back side of the light-guiding layer 10 via an adhesive layer 52. The direction-changing layer 60A has a light distribution control structure that allows at least a portion of light propagating in the light-guiding layer 10 (in the y direction) to be directed toward the front side. The light distribution control structure exemplified here has a plurality of internal spaces 64A, and the plurality of internal spaces 64A have a forward inclined surface that allows light to be directed toward the front side by total internal reflection. The direction-changing layer 60A having a plurality of internal spaces 64A is composed of a shaping film 64 having a recessed portion 64A (indicated by the same reference symbol as the internal space 64A) on the surface, and an adhesive layer 54. In addition, the shaping film 64 and the base material layer 30 are bonded together by the adhesive layer 54.

[0101] Figure 5 A schematic cross-sectional view of a light guide member 110B included in a lighting device according to another embodiment of the present invention is shown in FIG. Figure 5 A light source LS is also shown.

[0102] The light-guiding member 110B includes: a light-guiding layer 10B having a light-receiving side surface for receiving light emitted from a light source LS, and a direction-changing layer 60B arranged on the front side of the light-guiding layer 10B. The direction-changing layer 60B has a light distribution control structure that allows at least a portion of light propagating in the light-guiding layer 10B (in the y direction) to be directed toward the front side. The light distribution control structure exemplified here has a plurality of internal spaces 64A, each of which has a forward inclined surface that allows light to be directed toward the front side by total internal reflection. The direction-changing layer 60B having a plurality of internal spaces 64A is composed of a shaping film 64 having a recessed portion 64A (indicated by the same reference symbol as the internal space 64A) on the surface, and an adhesive layer 54. The shaping film 64 and the light-guiding layer 10B are bonded together by the adhesive layer 54.

[0103] The shaped film for forming the internal space can be manufactured as described below, for example. The concave-convex shaped film was manufactured according to the method described in the Japanese Patent Table 2013-524288 Gazette. Specifically, the surface of the polymethyl methacrylate (PMMA) film was coated with a varnish (FINECURE RM-64 manufactured by Sanyo Chemical Industries, Ltd.), and an optical pattern was embossed on the film surface containing the varnish, and then the varnish was cured, thereby manufacturing the target concave-convex shaped film. The total thickness of the concave-convex shaped film was 130 μm.

[0104] The light guide layer is formed of a known material with high transmittance to visible light. For example, the light guide layer is formed of acrylic resins such as polymethyl methacrylate (PMMA), polycarbonate (PC) resins, cycloolefin resins, and glass (for example, quartz glass, alkali-free glass, borosilicate glass). The refractive index n of the light guide layer is GP For example, it is greater than 1.40 and less than 1.80. It should be noted that, unless otherwise specified, the refractive index refers to the refractive index measured by an ellipsometer at a wavelength of 550 nm. The thickness of the light-guiding layer can be appropriately set according to the application. The thickness of the light-guiding layer is, for example, greater than 0.05 mm and less than 50 mm.

[0105] The substrate layer is formed of a plastic having a high transmittance to visible light, which is also used for the light guide layer, such as an acrylic resin such as polymethyl methacrylate (PMMA), a polycarbonate (PC) resin, or a cycloolefin resin. The thickness of the substrate layer is, for example, 1 μm or more and 1000 μm or less, preferably 10 μm or more and 100 μm or less, and more preferably 20 μm or more and 80 μm or less. The refractive index of the substrate layer is independently preferably 1.40 or more and 1.70 or less, and more preferably 1.43 or more and 1.65 or less.

[0106] The thickness of the adhesive layer is independently, for example, 0.1 μm or more and 100 μm or less, preferably 0.3 μm or more and 100 μm or less, and more preferably 0.5 μm or more and 50 μm or less. The refractive index of the adhesive layer is independently preferably 1.42 or more and 1.60 or less, and more preferably 1.47 or more and 1.58 or less. In addition, the refractive index of the adhesive layer is preferably close to the refractive index of the light-guiding layer, the shaping film or the substrate layer connected thereto, and the absolute value of the difference in refractive index is preferably 0.2 or less.

[0107] The adhesive layer that is in contact with the concave portion on the surface of the excipient film and constitutes the internal space is preferably capable of bonding without filling the concave portion on the surface of the excipient film. As an adhesive suitable for forming such an adhesive layer, the adhesive described in International Publication No. 2021 / 167090, International Publication No. 2021 / 167091 or International Publication No. 2022 / 176658 of the applicant can be suitably used. The disclosures of these applications are all cited in this specification. The polyester adhesive described in International Publication No. 2022 / 176658 is particularly preferred.

[0108] In the light guide component 110A, when a glass plate is used for the light guide layer 10, an optical component having excellent hardness (strength) and flame retardancy can be obtained simply by disposing the second cover member 200R on the back side of the light guide component 110A. In addition, in the light guide component 110B, when a glass plate is used for the light guide layer 10B, an optical component having excellent hardness (strength) and flame retardancy can be obtained simply by disposing the first cover member 200F on the front side of the light guide component 110B. Of course, in any case, the first cover member 200F can be disposed on the front side, and the second cover member 200R can be disposed on the back side. In addition, in applications where hardness (strength) and / or flame retardancy are not required, the light guide layer 10 or 10B can be formed of plastic. In the case where the light guide layer 10 or 10B is formed of plastic, it is preferred to use an acrylic resin having a particularly high visible light transmittance.

[0109] Use with Figure 4 Optical components having various structures were attempted to be produced using light guide components having the same structure as the light guide component 110A shown in the figure (Examples 1 to 12 and Comparative Examples). Acrylic (PMMA) plates or glass plates were used as the first cover component 200F and the second cover component 200R. In addition, an optical component having an anti-reflection film (AR) provided on the front side (outer side) of the first cover component 200F and an optical component having an anti-reflection film (AR) provided on the front side (inner side) of the second cover component 200R were produced. As the anti-reflection film, Luclear II manufactured by Sangetsu Co., Ltd. was used. An optical component having neither the first cover component 200F nor the second cover component 200R was used as a comparative example.

[0110] As the light guide component 110A, a light guide component having the parameters shown in the following Table 1 was used. As the light guide layer 10, an acrylic plate with a thickness of 5 mm was used, as the base material layer 30, an acrylic film with a thickness of 30 μm was used, and the thickness of the excipient film 64 was set to 40 μm. The adhesive layers 52 and 54 used an acrylic adhesive with a thickness of 50 μm. The visible light transmittance of the light guide component was 93%, and the haze value was 3%. The visible light transmittance and the haze value were measured using, for example, a haze meter (Murakami Color Technology Research Institute: trade name HM-150).

[0111] [Table 1]

[0112]

[0113] The structure and characteristics of the optical components attempted to be produced are shown in Table 2 below. Using a halogen lamp as a light source, the reflectivity of the surface of the first cover member 200F (the surface on the front side (outside)) and the reflectivity of the surface of the second cover member 200R (the surface on the front side (inside)) were measured using an ultraviolet visible near-infrared spectrophotometer UH4150. For appearance, the transmittance of the optical components was evaluated by visual observation. When observing objects such as experimental equipment through each optical component with the naked eye, it is set as excellent (◎) when there is very little reflection and the object can be observed very clearly, it is set as good (○) when there is little reflection and the object can be observed clearly, and it is set as qualified (△) when there is a little reflection but the object can be observed. The optical component of the embodiment has at least the first cover member 200F or the second cover member 200R, so the surface protection of the light guide member is sufficient (○), and the optical component having both the first cover member 200F and the second cover member 200R is particularly excellent in terms of surface protection of the light guide member (◎). The optical member of the comparative example does not have any of the first cover member 200F and the second cover member 200R, and therefore cannot protect the surface of the light guide member (×). In addition, regarding flame retardancy in building material applications, an optical member in which only one of the first cover member 200F and the second cover member 200R has a glass plate is rated as good (○), and an optical member in which both the first cover member 200F and the second cover member 200R have a glass plate is rated as excellent (◎).

[0114] [Table 2]

[0115]

[0116] As described above, the optical member according to the embodiment of the present invention includes the cover member that protects the light guide member and has a high transmittance of visible light, so that the appearance is not impaired.

[0117] Figure 6 , a schematic partial stereoscopic view of an optical component 300A according to an embodiment of the present invention is shown. The optical component 300A is, for example, multi-layer glass. The multi-layer glass 300A has a light guide component 110A or 110B, and a first cover component 200F or a second cover component 200R. The light guide component 110A or 110B and the first cover component 200F or the second cover component 200R are fixed at a certain interval by a spacer 80, and a gas layer GL is formed in a closed space. The emission direction of light (i.e., the front side) can be selected according to the orientation of the light guide component 110A or 110B. The spacer 80 has a desiccant 82 inside to remove moisture from the gas in the gas layer GL.

[0118] Figure 7, a schematic partial stereoscopic view of an optical component 300B according to an embodiment of the present invention is shown. The optical component 300B is, for example, a multi-layer glass. The multi-layer glass 300B has a light guide component 110A or 110B, a first cover component 200F, and a second cover component 200R. The light emission direction (i.e., the front side) can be selected according to the orientation of the light guide component 110A or 110B. That is, the configuration of the first cover component 200F and the second cover component 200R can be interchanged. The light guide component 110A or 110B and the first cover component 200F or the second cover component 200R are fixed at a certain interval by a spacer 80, and a gas layer GL is formed in a closed space.

[0119] Industrial Applicability

[0120] The lighting device according to the embodiment of the present invention can be used in various scenes including windows and walls.

Claims

1. An optical member comprising a light guide member and at least one cover member, and configured so that light is emitted toward a front side, The light guide member comprises: A light guide layer having a light receiving side surface for receiving light emitted from a light source, and a light distribution control structure for allowing at least a portion of the light propagating in the light guide layer to be directed toward the front side, The at least one cover member includes a first cover member disposed on the front side of the light guide member or a second cover member disposed on the back side of the light guide member opposite to the front side, The optical member is configured such that more than 50% of the light incident on the light guide layer is emitted from the front surface side of the light guide member.

2. The optical component according to claim 1, wherein The reflectance of the first cover member and the second cover member with respect to visible light vertically incident from the light guide member side is 25% or less.

3. The optical component according to claim 1, wherein The first cover member or the second cover member includes a glass plate.

4. The optical component according to claim 3, wherein The first cover member further includes an antireflection layer provided on at least one main surface of the glass plate.

5. The optical component according to any one of claims 1 to 4, wherein When the light having the highest intensity in the light distribution of the light emitted from the light guide member toward the front side is set as the first principal light, and the light having the highest intensity in the light distribution of the light emitted from the light guide member toward the back side is set as the second principal light, A polar angle θ1 of the first principal ray with respect to the normal line of the light guide layer is smaller than a polar angle θ2 of the second principal ray with respect to the normal line of the light guide layer.

6. The optical component according to claim 5, wherein The polar angle θ1 is greater than or equal to 0° and less than 40°, and the polar angle θ2 is greater than or equal to 30° and less than 70°.

7. The optical component according to any one of claims 1 to 4, wherein The light guide member is arranged to be isolated from the at least one cover member via a gas layer.

8. The optical component according to any one of claims 1 to 4, wherein The light guide layer is formed of acrylic resin.

9. The optical component according to any one of claims 1 to 4, wherein The light distribution control structure has a plurality of internal spaces, and the plurality of internal spaces have a front inclined surface that allows light to be directed toward the front side by total internal reflection.

10. The optical component according to any one of claims 1 to 4, wherein The light distribution control structure is formed on a direction changing layer, and the direction changing layer is arranged on the front side or the back side of the light guiding layer.

11. The optical component according to any one of claims 1 to 4, wherein The light guide component has a visible light transmittance of 60% or more and a haze value of less than 10%.

12. A lighting device, comprising: The optical member according to any one of claims 1 to 4, and A light source is arranged so as to emit light toward the light receiving surface of the optical member.

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