Light guide member for lighting device, and lighting device

Abstract

The present invention is a light guide member for an illumination device having a first emission surface and a second emission surface opposite to the first emission surface, and having: a light receiving portion that receives light emitted from a light source (LS); a light guide layer (10) having a first main surface on the side of the first emission surface and a second main surface on the side of the second emission surface; and a light distribution control structure having a plurality of internal spaces (64A); each of the plurality of internal spaces (64A) having a first inclined surface (ISa) on the side of the first emission surface and a second inclined surface (ISb) opposite to the first inclined surface (ISa) by internal total internal reflection; and configured such that a first light (LRa) with a first light distribution is emitted from the first emission surface and a second light (LRb) with a second light distribution is emitted from the second emission surface.

Description

[Technical Field]

[0001] This invention relates to a light guide component and a lighting device, and more particularly to a sheet-like lighting device having a light source and a light guide layer. Here, "sheet-like" is used to include the meaning of plate-like or film-like, regardless of the rigidity (flexibility) and thickness of the sheet material. Furthermore, the sheet-like lighting device can be used in various forms such as roller-like. [Previous Technology]

[0002] Sheet-shaped lighting devices with a light source and a light guide layer are used, for example, as backlights or front lights for liquid crystal display devices. Furthermore, in recent years, the use of next-generation semiconductor lighting (Solid State Lighting: SSL), represented by LED lighting, has been continuously advancing. For example, a type of lighting called architectural entertainment lighting is being proposed, which combines architectural components with lighting devices to create design-oriented or entertaining lighting.

[0003] For example, Patent Document 1 discloses a dual-purpose window for both single-sided lighting and illumination, which has a light source at one end of a plate-shaped transparent substrate. During nighttime illumination, it functions as an illumination device that allows light emitted from the light source and guided within the transparent substrate to exit from one side of the transparent substrate. During daytime or other non-illuminating times, it functions as a transparent window. Furthermore, Patent Documents 2 to 5 disclose sheet-like lighting devices with a light distribution structure utilizing total internal reflection at the interface of an air cavity (internal space). All disclosures of Patent Documents 2 to 5 are incorporated herein by reference. [Prior Art Documents] [Patent Documents]

[0004] Patent Document 1: International Publication No. 2019 / 102959; Patent Document 2: International Publication No. 2019 / 182091; Patent Document 3: International Publication No. 2019 / 146628; Patent Document 4: International Publication No. 2011 / 124765; Patent Document 5: International Publication No. 2019 / 087118 [Summary of the Invention]

[0005] [The problem the invention aims to solve]

[0006] Previous sheet-like lighting devices emitted light only from one of the two main surfaces of the lighting device that face opposite directions. The object of the present invention is to provide a light guide member and lighting device for a sheet-like lighting device that can emit light from two main surfaces facing opposite directions. [Technical Means for Solving the Problem]

[0007] According to an embodiment of the present invention, a solution described in the following items is provided. [Item 1] A light guide member for a lighting device, having a first emitting surface and a second emitting surface opposite to the first emitting surface, and having: a light receiving portion that receives light emitted from a light source; a light guide layer having a first main surface on the side of the first emitting surface and a second main surface on the side of the second emitting surface; and a light distribution control structure having a plurality of internal spaces; and each of the plurality of internal spaces having a first inclined surface on the side of the first emitting surface that, by means of internal total internal reflection, causes a portion of the light transmitted within the light guide layer to face the side of the first emitting surface; and a second inclined surface on the side opposite to the first inclined surface; and configured such that a first light with a first light distribution is emitted from the first emitting surface and a second light with a second light distribution is emitted from the second emitting surface. [Item 2] As in the light guide member for the lighting device of Item 1, when the light ray with the highest intensity in the first light distribution is designated as the first principal ray, and the light ray with the highest intensity in the second light distribution is designated as the second principal ray, the ratio of the intensity of the first principal ray to the intensity of the second principal ray is in the range of 1:4 or more and 4:1 or less. [Item 3] As in the light guide member for the lighting device of Item 2, the ratio of the intensity of the first principal ray to the intensity of the second principal ray is in the range of 0.5 or more and 1.3 or less. [Item 4] As in the light guide member for the lighting device of Item 2 or 3, the polar angle θ1 between the first principal ray and the normal to the first emitting surface is smaller than the polar angle θ2 between the second principal ray and the normal to the second emitting surface. [Item 5] As in the light guide member for the lighting device of Item 4, the polar angle θ1 is 0° or more but less than 40°, and the polar angle θ2 is 30° or more but less than 70°. [Item 6] A light guide member for a lighting device according to any one of Items 1 to 5, wherein the half-value angle of the light guiding direction of the light guide layer of the first principal ray is 67° or less. [Item 7] A light guide member for a lighting device according to any one of Items 1 to 6, wherein the half-value angle of the light guiding direction of the light guide layer of the first principal ray is 24° or more. [Item 8] A light guide member for a lighting device according to any one of Items 1 to 7, wherein the light distribution control structure is formed in a direction conversion layer disposed on the first main surface side or the second main surface side of the light guide layer. [Item 9] A light guide member for a lighting device according to any one of Items 1 to 8, wherein the tilt angle θa of the first inclined surface is 10° or more and 70° or less. [Item 10] A light guide member for a lighting device according to any one of Items 1 to 9, wherein the tilt angle θb of the second inclined surface is 50° or more and 100° or less. [Item 11] A light guide member for a lighting device as described in any of Items 1 to 10, wherein when viewed from the normal direction relative to the first main surface of the light guide layer, the area of ​​the plurality of internal spaces occupies 80% or less of the area of ​​the light guide layer.[Item 12] A light guide member for an illumination device according to any one of items 1 to 11, wherein the plurality of internal spaces are discretely arranged in the light guiding direction of the light guide layer and in directions intersecting the light guiding direction. [Item 13] A light guide member for an illumination device according to any one of items 1 to 12, wherein when viewed from the normal direction relative to the first main surface of the light guide layer, the first inclined surface forms a curved surface convex toward the light source side. [Item 14] A light guide member for an illumination device according to any one of items 1 to 13, wherein the visible light transmittance is 60% or more, and the turbidity value is less than 30%. [Item 15] An illumination device comprising: a light guide member for an illumination device according to any one of items 1 to 14; and a light source that emits light toward the light-receiving portion. [Effects of the Invention].

[0008] According to an embodiment of the present invention, a light guide member for a sheet-shaped lighting device and a lighting device are provided, which can emit light from two main surfaces facing opposite directions. In a certain embodiment, the visible light transmittance of the light guide member for the lighting device is 60% or more, and the turbidity value is less than 30%, so that objects can be easily seen (displayed) through the light guide member for the lighting device.

Implementation Method

[0010] Hereinafter, with reference to the drawings, a light guide member for a lighting device and a lighting device according to an embodiment of the present invention will be described. The light guide member for a lighting device and the lighting device according to an embodiment of the present invention are not limited to those illustrated below.

[0011] FIG1 shows a schematic cross-sectional view of an embodiment of the lighting device 100A of the present invention. The lighting device 100A is a sheet-shaped lighting device having two emission surfaces facing opposite directions. The lighting device 100A has a first emission surface (lower in FIG1) for emitting a first light LRa and a second emission surface (upper in FIG1) for emitting a second light LRb. The first light LRa is emitted towards the -Z direction in FIG1, and the second light LRb is emitted towards the Z direction.

[0012] The lighting device 100A includes a light source LS and a light guide member 100A(G) for the lighting device. Hereinafter, the light guide member for the lighting device will be indicated by the reference numeral (G) following the reference numeral of the lighting device 100A. The light guide member 100A(G) for the lighting device includes: a light-receiving portion that receives light emitted from the light source LS; a first main surface on the first emission surface side; a light guide layer 10 having a second main surface on the second emission surface side; and a light distribution control structure having a plurality of internal spaces 64A. The light-receiving portion of the light guide member 100A(G) for the lighting device is, for example, the side surface (light-receiving side surface) of the light guide layer 10 on the light source LS side. Each of the plurality of internal spaces 64A has a first inclined surface ISa on the side of the first emitting surface, and a second inclined surface ISb on the opposite side of the first inclined surface ISa, through total internal reflection (TIR). A second light LRb emanating from the second emitting surface enters the internal space 64A through the first inclined surface ISa and passes through the internal space 64A. The second light LRb passes through the upper surface of the internal space 64A (the interface with the adhesive layer 54) or the second inclined surface ISb. Of course, the first light LRa and the second light LRb can be refracted according to the refractive index of the material constituting the interface when passing through the interface.

[0013] In the light guide member 100A(G) for a lighting device, a light distribution control structure having a plurality of internal spaces 64A is formed in a direction conversion layer 60A disposed on the second main surface side of the light guide layer 10. The direction conversion layer 60A having a plurality of internal spaces 64A is composed of a shaping film 62A having recesses 64A on its surface (denoted by the same reference numerals as the internal spaces 64A) and an adhesive layer 54. Furthermore, the internal spaces 64A are not limited to this example; for example, as described later with reference to FIG17A, they may also be formed in a direction conversion layer 60B disposed on the first main surface side of the light guide layer 10. Alternatively, a plurality of internal spaces 64A (or internal spaces 64B as shown in FIG17A, etc.) may be formed within the light guide layer 10.

[0014] The light guide member 100A(G) for the lighting device is configured such that, by means of a light distribution control structure, a first light LRa having a first light distribution pattern is emitted from a first emitting surface, and a second light LRb having a second light distribution pattern is emitted from a second emitting surface. For example, when the light with the highest intensity in the first light distribution pattern is designated as the first principal light ray, and the light with the highest intensity in the second light distribution pattern is designated as the second principal light ray, for example, the ratio of the intensity of the first principal light ray to the intensity of the second principal light ray can be controlled within a range of 1:4 or higher and 4:1 or lower. As shown in the simulation results below, the ratio of the intensity of the first principal light ray to the intensity of the second principal light ray is, for example, within a range of 0.5 or higher and 1.3 or lower. Therefore, both the first light LRa and the second light LRb can be used for lighting.

[0015] For example, the polar angle θ1 between the first principal ray and the normal relative to the first exiting surface is smaller than the polar angle θ2 between the second principal ray and the normal relative to the second exiting surface. For example, the polar angle θ1 is 0° or more but less than 40°, and the polar angle θ2 is 30° or less but less than 70°. The first and second light distributions can be controlled, for example, by adjusting the cross-sectional shape, planar shape, size, arrangement density, and distribution of the internal space 64A (or the internal space 64B in FIG. 17A, etc.). As described later with reference to FIG. 3A, for example, the tilt angle θa of the first inclined surface ISa is 10° or more but less than 70°. Also, the tilt angle θb of the second inclined surface ISb is 50° or more but less than 100°. Although the cross-sectional shape of the internal space 64A is shown here as a triangle, it is not limited to this and can also be a trapezoid or the like.

[0016] The light guide member 100A(G) for the lighting device may, for example, have a visible light transmittance of 60% or more and a turbidity value of less than 30%. The visible light transmittance is preferably 70% or more, more preferably 80% or more. The turbidity value is preferably less than 10%, more preferably 5% or less. Because the light guide member 100A(G) for the lighting device of the embodiment of the present invention has a high visible light transmittance and a low turbidity value, objects can be observed (displayed) through the light guide member 100A(G). Here, light with a wavelength of 380 mm or more and 780 mm or less is defined as visible light. The visible light transmittance and turbidity value can be measured, for example, using a turbidity meter (manufactured by Murakami Color Technology Research Institute: trade name HM-150).

[0017] In the light distribution control structure, when the light guide layer 10 is viewed from the normal direction of the self-plane, the proportion of the area of ​​the plurality of internal spaces 64A occupying the area of ​​the light guide layer 10 (occupancy rate) is preferably 1% to 80%, with an upper limit of 50% or less, and further preferably 45% or less. To obtain higher transmittance and / or lower turbidity, it is preferably 30% or less, more preferably 10% or less, and further preferably 5% or less. For example, when the occupancy rate of the internal spaces is 50%, a turbidity of 30% can be obtained. Furthermore, the occupancy rate of the internal spaces 64A can be uniform, or it can be such that the brightness does not decrease even when the distance from the light source LS increases, with the occupancy rate increasing as the distance increases. For mass production using roll-to-roll or roll-to-sheet methods, the occupancy rate of the internal spaces 64A is preferably uniform.

[0018] A light guide member 100A(G) for a lighting device has a shaping film 62A bonded to the second main surface of the light guide layer 10 via an adhesive layer 52. The substrate layer 30 is bonded to the shaping film 62A via an adhesive layer 54 that forms the orientation conversion layer 60A. The light guide layer 10 and the substrate layer 30 can be transparent substrates or thin films. Preferred configurations of the light guide layer 10, substrate layer 30, shaping film 62A, and adhesive layers 52 and 54 will be described later.

[0019] Next, referring to Figure 2, an example of the plan shape and configuration of the interior space 64A will be described. Figure 2 shows a schematic top view of the lighting device 100A.

[0020] As shown in Figure 2, a plurality of internal spaces 64A are discretely arranged, for example, in the light guiding direction (Y direction) and the direction orthogonal to the light guiding direction (X direction) of the light guiding layer 10. The size (length, width W: see Figures 3A and 3B) of the internal spaces 64A is preferably, 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. Furthermore, from the viewpoint of light extraction efficiency, the height H (see Figure 3A) is preferably 1 μm or more and 100 μm or less.

[0021] Here, although an example is shown where a plurality of internal spaces 64A are discretely arranged in the light-guiding direction (Y direction) and the direction orthogonal to the light-guiding direction (X direction) of the light-guiding layer 10, it is not limited to this. The plurality of internal spaces 64A can be discretely arranged in the light-guiding direction (Y direction) and the direction intersecting the light-guiding direction of the light-guiding layer 10. The discrete arrangement of the internal spaces 64A can be appropriately set according to the shape of the light-guiding layer 10 or the obtained light distribution. Furthermore, although light is transmitted in various directions within the light-guiding layer 10, the Y direction is referred to as the light-guiding direction, and light with a component (non-zero) in the Y direction is said to be transmitted in the Y direction. The same applies to other directions. That is, light transmitted in the -Y direction includes all light with a component (non-zero) in the -Y direction.

[0022] A plurality of internal spaces 64 are discretely arranged, for example, in the light guiding direction and in directions intersecting the light guiding direction. The discrete arrangement may be periodic (regular) in at least one direction, or it may not be regular. However, from the point of view of mass production, it is preferable that the plurality of internal spaces 64 are arranged in the same manner. For example, in the example shown in FIG2, a plurality of internal spaces 64, which are substantially the same shape and have curved surfaces protruding in the same direction, are discretely, periodically and over the entire area arranged in the light guiding direction (Y direction) and in directions orthogonal to the light guiding direction (X direction) of the light guiding layer 10. In this case, the spacing Px is preferably, for example, 10 μm or more and 500 μm or less, and the spacing Py is preferably, for example, 10 μm or more and 500 μm or less. In the example shown in FIG2, there are internal spaces that are arranged with a half-spacing offset in both the Y direction and the X direction. In Examples 1 and 2 described below, Px is 200 μm and Py is 100 μm; in Examples 3 and 4, Px is 260 μm and Py is 160 μm.

[0023] As shown in Figure 2, when viewed from the normal direction relative to the first main surface of the light guide layer 10, the first inclined surface ISa forms a curved surface that protrudes toward the light source LS. The light source LS is, for example, an LED device, with a plurality of LED devices arranged in the X direction. Since the light emitted from each of the plurality of LED devices has a width relative to the Y direction, although the first inclined surface ISa has a curved surface that protrudes toward the light source LS, the first inclined surface ISa functions uniformly for light. Furthermore, a coupling optical system is provided between the light source LS and the light-receiving part of the light guide member 100A(G) for the illumination device, so that when light with higher parallelism (light with a smaller width relative to the Y direction) is incident, the first inclined surface ISa can be parallel to the X direction. Also, instead of a discrete internal space 64A, an internal space such as a groove (e.g., a triangular prism) extending in the X direction can be used.

[0024] Next, referring to Figures 3A, 3B, 3C, and 4, the shape of the interior space 64A will be described. Figure 3A is a schematic sectional view of the interior space 64A, Figure 3B is a schematic top view of the interior space 64A, and Figure 3C is a schematic top view showing changes in the interior space 64A. Figure 4 is a diagram showing an example of the curved surface shape of the first inclined surface ISa of the interior space 64A.

[0025] As shown in Figure 3A, the cross-sectional shape of the internal space 64A is, for example, triangular. The tilt angle θa of the first tilted surface ISa on the light source LS side is, for example, 10° or more and 70° or less. If the tilt angle θa is less than 10°, the controllability of light distribution decreases, and sometimes the light extraction efficiency also decreases. On the other hand, if the tilt angle θa exceeds 70°, for example, the processing of the shaping film sometimes becomes difficult. Also, the tilt angle θb of the second tilted surface ISa is, for example, 50° or more and 100° or less. If the tilt angle θb is less than 50°, sometimes scattered light occurs in an undesirable direction. On the other hand, if the tilt angle θb exceeds 100°, for example, the processing of the shaping film sometimes becomes difficult. As shown in Figures 3B and 3C, the length L of the internal space 64A 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, more than twice the width W. The height H (refer to Figure 3A) is preferably between 1 μm and 100 μm. Furthermore, due to the processing precision required when forming a molded film containing a recess with the planar shape shown in Figure 3B, sometimes a recess with the planar shape shown in Figure 3C is formed. In this case, the planar shape of the internal space can also be characterized by the length L and the width W.

[0026] The curved surface of the first inclined surface ISa protruding towards the light source LS is represented, for example, by the diagram shown in FIG4. In Examples 1 to 3, an illumination device was fabricated having a length L of 60 μm, an inclination angle θa of the first inclined surface ISa of 30°, 40°, and 49°, and the first inclined surface ISa forming an internal space 64A of the curved surface shown in FIG4. The width W in Examples 1 to 3 is approximately 13.9 μm, approximately 9.5 μm, and approximately 7.0 μm, respectively. The curved surface shown in FIG4 is represented, for example, by a quartic curve. Furthermore, the inclination angle θb of the second inclined surface ISa is 85° in Examples 1 to 3. The illumination devices of Examples 1 to 3 have a substantially identical structure to the illumination device 100A shown in FIG1. ​​Example 4 is a simplified illumination device using the same shaping film as in Example 3, but omitting the substrate layer 30 and adhesive layer 54 shown in FIG1. The size of the shaping film in the lighting devices of Examples 1 to 3 (long side direction: light guiding direction × width direction) is approximately 600 mm × approximately 700 mm, while the size of the shaping film in the lighting device of Example 4 (long side direction: light guiding direction × width direction) is approximately 170 mm × approximately 120 mm.

[0027] Figure 5 shows a coordinate system representing the 3D light distribution of the emitted light from the lighting device. In each lighting device, the first light distribution of the first light emitted from the first emitting surface is represented by the polar angle θ1 between the first principal ray and the normal to the first emitting surface, and the second light distribution of the second light emitted from the second emitting surface is represented by the polar angle θ2 between the second principal ray and the normal to the second emitting surface. Here, the ray with the highest intensity in the first light distribution is designated as the first principal ray, and the ray with the highest intensity in the second light distribution is designated as the second principal ray. The light distribution in each lighting device of Examples 1-3 was measured using a light distribution measurement device (PIMACS, Neolight 9500). The light distribution in the lighting device of Example 4 was measured using a light distribution evaluation device (Radiant Conoscope 070, Radiant Vision Systems).

[0028] The coordinate system representing the 3D light distribution designates the side emitting the first light beam LRa as the front side and the side emitting the second light beam LRb as the back side. The length direction (light guiding direction) of the light guide layer is vertical (longitudinal), and the width direction is horizontal (horizontal). The light distribution is represented by the luminance (brightness) of the polar angles in the vertical direction (represented by arrow V in the figure) and the horizontal direction (represented by arrow L in the figure). Sometimes the polar angle in the V direction is simply represented as V, and the polar angle in the L direction is simply represented as L.

[0029] Figure 6A shows the light distribution of the light emitted from the lighting device of Embodiment 1. Figure 6B is a graph showing the light distribution of the light emitted from the lighting device of Embodiment 1 in the V direction, and Figure 6C is a graph showing the light distribution of the light emitted from the lighting device of Embodiment 1 in the L direction. Figure 7A shows the light distribution of the light emitted from the lighting device of Embodiment 2. Figure 7B is a graph showing the light distribution of the light emitted from the lighting device of Embodiment 2 in the V direction, and Figure 7C is a graph showing the light distribution of the light emitted from the lighting device of Embodiment 2 in the L direction. Figure 8A shows the light distribution of the light emitted from the lighting device of Embodiment 3. Figure 8B is a graph showing the light distribution of the light emitted from the lighting device of Embodiment 3 in the V direction, and Figure 8C is a graph showing the light distribution of the light emitted from the lighting device of Embodiment 3 in the L direction. Furthermore, Figure 8D is a graph showing the light distribution in the V direction of the light emitted from the lighting device of Embodiment 4.

[0030] As shown in Figure 6A, the polar angle θ1 of the light distribution of the lighting device of Embodiment 1 is approximately 30°, and the polar angle θ2 is approximately 48°. Also, as shown in Figure 6B, the half-value (FWHM) angle in the V direction is approximately 67°, and the half-value angle in the L direction is approximately 94°. As shown in Figure 7A, the polar angle θ1 of the light distribution of the lighting device of Embodiment 2 is approximately 10°, and the polar angle θ2 is approximately 60°. Also, as shown in Figure 7B, the half-value (FWHM) angle in the V direction is approximately 54°, and the half-value angle in the L direction is approximately 94°. As shown in Figure 8A, the polar angle θ1 of the light distribution of the lighting device of Embodiment 3 is approximately 8°, and the polar angle θ2 is approximately 58°. Also, as shown in Figure 8B, the half-value (FWHM) angle in the V direction is approximately 45°, and the half-value angle in the L direction is approximately 86°. In the lighting device of any of the embodiments 1 to 3, the polar angle θ1 of the first principal ray LRa and the normal to the first emitting surface is smaller than the polar angle θ2 of the second principal ray LRb and the normal to the second emitting surface. Furthermore, the sum of the polar angles θ1 and θ2 is approximately 78°, approximately 70°, and approximately 63°, falling within the range of approximately 60° to 80°. Also, as shown in Figure 8D, the half-value angle in the V direction can be reduced to at least approximately 24°.

[0031] As is known from the results of Embodiments 1 to 3, the half-value angle of the V direction of the first light can be set to approximately 45° or more and approximately 67° or less, and the half-value angle of the L direction of the second light can be controlled within the range of approximately 86° or more and approximately 94° or less. Furthermore, based on the results of Embodiment 4, the lower limit of the half-value angle of the V direction of the first light can be reduced to at least approximately 24°.

[0032] Table 1 below shows the ratio of the intensity of the first main light beam to the intensity of the second main light beam of each lighting device in Examples 1 to 4, as well as the polar angle θ1, the half-value angle in the V direction, and the half-value angle in the L direction. Table 1 also shows the tilt angles θa and θb and the ratio of the area of ​​the internal space to the area of ​​the light guide layer (internal space area ratio).

[0033] [Table 1]

[0034] It is understood that in any embodiment of the lighting device, the ratio of the intensity of the first main light to the intensity of the second main light is within the range of 0.9 to 1.3, which can illuminate both sides of the sheet-like lighting device. The larger the internal space occupancy ratio, the greater the ratio of the intensity of the first main light to the intensity of the second main light. The internal space occupancy ratio is 5% or less, and it has a visible light transmittance of 80% or more and a turbidity value of 5% or less.

[0035] Furthermore, a simulation was performed using Light Tools (manufactured by Synopsys), a lighting design analysis software well-known for its capabilities. Figure 9 shows the results obtained through simulation, comparing the intensity of the first principal ray to the intensity of the second principal ray when the tilt angle θa of the interior space 64A is changed. These results are displayed alongside the measured results from Examples 1 to 3 described above. In the simulation, the interior space area ratio was set to 1.20%.

[0036] As shown in Figure 9, the ratio of the intensity of the first principal ray to the intensity of the second principal ray in Embodiment 3, with an internal space occupancy rate of 1.20%, is largely consistent with the simulation results. According to the simulation results, the ratio of the intensity of the first principal ray to the intensity of the second principal ray is minimized at a tilt angle θa of 45°, and increases when the tilt angle θa is greater than approximately 45° (e.g., above 49°) or less than (e.g., below 40°). Therefore, the ratio of the intensity of the first principal ray to the intensity of the second principal ray can be varied by adjusting the internal space occupancy rate and the tilt angle θa.

[0037] Table 2 and Figure 10 below show the results obtained by simulation of the values ​​of the intensity of the first principal ray / the intensity of the second principal ray when the tilt angle θa of the internal space 64A of the lighting device of Embodiment 3 is changed.

[0038] [Table 2]

[0039] Furthermore, Figure 11 shows the result obtained by simulation of the ratio of the intensity of the first principal ray to the intensity of the second principal ray when the tilt angle θb of the internal space 64A of the lighting device of Embodiment 3 is changed. In the simulation, the area ratio of the internal space is set to 1.20%. As can be seen from Table 2, Figures 10 and 11, by changing the tilt angles θa and θb, the ratio of the intensity of the first principal ray to the intensity of the second principal ray can be adjusted within a range of 0.5 to 1.3. Moreover, by adopting the configuration of providing a light absorption layer on the light incident side as described later with reference to Figures 18A and 18B, the ratio of the intensity of the first principal ray to the intensity of the second principal ray can be controlled within a range of 1:4 to 4:1.

[0040] Furthermore, Figure 12 shows the direction of the first principal ray (polar angle θ1) when the tilt angle θa of the internal space 64A of the lighting device of Embodiment 3 is changed, and Figure 13 shows the direction of the first principal ray (polar angle θ1) when the tilt angle θb is changed. As can be seen from Figure 12, the direction of the first principal ray (polar angle θ1) can be changed by changing the tilt angle θa. On the other hand, as can be seen from Figure 13, the tilt angle θb does not affect the direction of the first principal ray (polar angle θ1).

[0041] Furthermore, Figure 14 shows the direction of the second principal ray (polar angle θ2) when the tilt angle θa of the internal space 64A of the lighting device of Embodiment 3 is changed, and Figure 15 shows the direction of the second principal ray (polar angle θ2) when the tilt angle θb is changed. As can be seen from Figure 14, the direction of the second principal ray (polar angle θ2) can be changed by changing the tilt angle θa. On the other hand, as can be seen from Figure 15, the tilt angle θb does not affect the direction of the second principal ray (polar angle θ2).

[0042] As described above, the light distribution of the emitted light from the lighting device can be adjusted by adjusting the internal space occupancy ratio, tilt angles θa and θb. For example, the tilt angle θb does not affect the direction of the principal rays (polar angles θ1 and θ2), but on the other hand, it almost linearly affects the ratio of the intensity of the first principal ray to the intensity of the second principal ray (see Figure 11). Therefore, after determining the internal space occupancy ratio and the tilt angle θa, the tilt angle θb is changed, thereby adjusting the intensity of the first principal ray and the intensity of the second principal ray.

[0043] The light guide member and lighting device of the embodiment of the present invention are not limited to the above examples and various modifications can be made. The lighting devices 100A1, 100A2, 100A3 and 100A4 shown in FIG16A, FIG16B, FIG16C and FIG16D are the same as the lighting device 100A shown in FIG1, and are examples of lighting devices having a light distribution control structure (i.e., a plurality of internal spaces 64A) with the first emission surface facing downward.

[0044] The light guide member 100A1(G) of the lighting device 100A1 shown in FIG. 16A has an anti-reflective layer 40A instead of the substrate layer 30 of the light guide member 100A(G) of the lighting device 100A shown in FIG. 1. Alternatively, a hard coating layer (e.g., pencil hardness H or higher) may be provided instead of the anti-reflective layer 40A, or both an anti-reflective layer and a hard coating layer may be provided. Furthermore, the anti-reflective layer and / or the hard coating layer may be provided on the first main surface (lower side) of the light guide layer 10. The anti-reflective layer and the hard coating layer may be formed using known materials and known methods. This is common to other illustrated lighting devices.

[0045] The light guide member 100A2(G) for the lighting device of the lighting device 100A2 shown in FIG. 16B further has a low refractive index layer 20A on the second emitting surface side of the direction conversion layer 60A. If the low refractive index layer 20A is provided, an interface that can totally reflect light is formed between the direction conversion layer 60A and the low refractive index layer 20A. Therefore, even if there are defects such as dirt, dents, or damage on the surface of the second emitting surface side of the light guide member, the optical performance of the light guide member can be suppressed from being affected by such defects. Furthermore, the light guide member 100A3(G) for the lighting device of the lighting device 100A3 shown in FIG. 16C may also have a low refractive index layer 20B provided on the first main surface (lower side) of the light guide layer 10. Furthermore, as shown in Figure 16D, the light guide member 100A4(G) for the lighting device 100A4 can also have a low refractive index layer 20A provided on the second emitting surface side of the direction conversion layer 60A, and a low refractive index layer 20B provided on the first main surface (lower side) of the light guide layer 10. When providing the anti-reflective layer, hard coating layer, and low refractive index layer, adhesive layers 52, 55, 56, and 58 can be appropriately provided as needed.

[0046] Next, the lighting devices 100B1, 100B2, 100B3 and 100B4 shown in FIG17A, FIG17B, FIG17C and FIG17D show examples of lighting devices that are different from the lighting device 100A shown in FIG1 and have light guide members 100B1(G), 100B2(G), 100B3(G) and 100B4(G) with a light distribution control structure (i.e., a plurality of internal spaces 64B) arranged with the first emission surface facing upward.

[0047] The light guide member 100B1 (G) of the lighting device 100B1 shown in FIG. 17A has a direction conversion layer 60B having a light distribution control structure (i.e., a plurality of internal spaces 64B) configured with the first emitting surface facing upward. The direction conversion layer 60B is composed of a shaping film 62B with recesses 64B on its surface (denoted by the same reference numeral as the internal space 64B) and an adhesive layer 54. The light distribution control structure may also be formed within the light guide layer 10. The lighting device 100B1 has an anti-reflective layer 40A on the first emitting surface side of the direction conversion layer 60B. Alternatively, a hard coating (e.g., pencil hardness H or higher) may be provided instead of the anti-reflective layer 40A, or both an anti-reflective layer and a hard coating may be provided.

[0048] The light guide member 100B2(G) for the lighting device of the lighting device 100B2 shown in FIG17B further has a low refractive index layer 20A on the first emitting surface side of the direction conversion layer 60B. If the low refractive index layer 20A is provided, an interface that can totally reflect light is formed between the direction conversion layer 60B and the low refractive index layer 20A. Therefore, even if there are defects such as dirt, dents, or damage on the surface of the first emitting surface side of the light guide member, the optical performance of the light guide member can be suppressed from being affected by such defects. Furthermore, the light guide member 100B3(G) for the lighting device of the lighting device 100B3 shown in FIG17C may also have a low refractive index layer 20B provided on the second main surface (lower side) of the light guide layer 10. Furthermore, the light guide member 100B1(G) for the lighting device 100B4 shown in Figure 17D may also have a low refractive index layer 20A provided on the first emitting surface side of the direction conversion layer 60B, and a low refractive index layer 20B provided on the second main surface (lower side) of the light guide layer 10.

[0049] The lighting device of the embodiment of the present invention can be further modified as follows. FIG18A shows a schematic cross-sectional view of another lighting device 100A3_1 of the embodiment of the present invention, and FIG18B shows a schematic cross-sectional view of another lighting device 100A3_2 of the embodiment of the present invention. Lighting device 100A3_1 and lighting device 100A3_2 are variations of lighting device 100A3 shown in FIG16C. The other lighting devices described above can also be modified in the same way.

[0050] The light guide member 100A3_1(G) of the lighting device 100A3_1 shown in FIG18A has light absorption layers 70A and 70B at the ends of the upper and lower emission surfaces (first and second emission surfaces) of the light guide member 100A3_1(G) of the lighting device 100A3 shown in FIG16C on the light source LS side. The light absorption layers 70A and 70B absorb visible light and are black layers, for example, they can also be black adhesive tape. The light absorption layers 70A and 70B have a width of about 10 mm away from the light source LS side, and are provided along the light-receiving part of the light guide member 100A3_1(G) of the lighting device (for example, along the short side of the light guide member 100A(G) of the lighting device shown in FIG2).

[0051] The light guide member 100A3_1(G) for the lighting device shown in FIG18A has light absorption layers 70A and 70B at the ends of the first and second emitting surfaces (upper and lower emitting surfaces) of the light guide member 100A3_1(G) for the lighting device shown in FIG16C on the light source LS side. The light absorption layers 70A and 70B absorb visible light and are black layers, for example, they can be black adhesive tape. The light absorption layers 70A and 70B have a width of about 10 mm away from the light source LS side, and are disposed along the light-receiving part of the light guide member 100A3_1(G) for the lighting device (for example, along the short side of the light guide member 100A(G) for the lighting device shown in FIG2).

[0052] Light absorption layers 70A and 70B absorb a portion of the light incident from the light source LS onto the light guide layer 10. Without light absorption layers 70A and 70B, the light absorbed by these layers is totally reflected by the first and second exit surfaces (interfaces with air) near the end of the light guide member 100A3_1(G) on the light source LS side, including the light returning to the light guide member 100A3_1(G). Therefore, by providing light absorption layers 70A and 70B and adjusting their widths, the angle of incidence of the light transmitted by the light guide member 100A3_1(G) relative to the first and second exit surfaces can be limited. As a result, for example, the ratio of the intensity of the first principal ray to the intensity of the second principal ray can be controlled within a range of 1:4 or higher and 4:1 or lower. Alternatively, only one of the light absorption layers 70A and 70B may be provided, and the widths of the light absorption layers 70A and / or 70B may be set independently and appropriately.

[0053] The light guide member 100A3_2(G) for the lighting device 100A3_2 shown in FIG18B has exposed portions of the first and second main surfaces of the light guide layer 10 of the light guide member 100A3(G) for the lighting device 100A3 shown in FIG16C at the light source LS side end. Light absorption layers 70A and 70B are provided on the exposed first and second main surfaces. Light absorption layers 70A and 70B absorb a portion of the light incident from the light source LS onto the light guide layer 10. If there were no light absorption layers 70A and 70B, the light absorbed by the light absorption layers 70A and 70B would be totally reflected by the exposed first and second surfaces (interface with air) of the light guide layer 10 and contained within the light guide layer 10. Therefore, by providing light absorption layers 70A and 70B and adjusting their widths, the angle of incidence of light transmitted within the light guide layer 10 relative to the first and second principal surfaces of the light guide layer 10 can be limited. As a result, for example, the ratio of the intensity of the first principal ray to the intensity of the second principal ray can be controlled within a range of 1:4 to 4:1. Alternatively, only one of the light absorption layers 70A and 70B may be provided, and the widths of the light absorption layers 70A and / or 70B can be independently and appropriately set.

[0054] Furthermore, in Figures 16A-16D, 17A-17D, 18A, and 18B, although the illustrations are omitted, the low refractive index layers 20A and 20B and the hard coating and / or anti-reflective layers 40A and 40B each have a substrate layer on the adhesive layer side. The substrate layers respectively function to support the low refractive index layers and the hard coating and / or anti-reflective layers. The thickness of each substrate layer is independent, 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 each substrate layer is independent, preferably 1.40 or more and 1.70 or less, and more preferably 1.43 or more and 1.65 or less. The substrate layer is, for example, an acrylic film.

[0055] A preferred example of each component of the lighting device according to an embodiment of the present invention will be described.

[0056] The shaped film used to form the internal space can be manufactured, for example, as follows. The embossed film is manufactured according to the method described in Japanese Patent Publication No. 2013-524288. Specifically, an optical pattern is embossed on the surface of a polymethyl methacrylate (PMMA) film by coating the surface with a fast-drying varnish (Finecure RM-64 manufactured by Sanyo Chemical Industries, Ltd.), and then the varnish is cured to produce the desired embossed film. The total thickness of the embossed film is 130 μm.

[0057] The light guide layer 10 is formed of a well-known material with high transmittance of visible light. The light guide layer 10 is formed, for example, of acrylic resins such as polymethyl methacrylate (PMMA), polycarbonate (PC) resins, cyclic olefin resins, or glass (e.g., quartz glass, alkali-free glass, borosilicate glass). The refractive index nGP of the light guide layer 10 is, for example, 1.40 or higher and 1.80 or lower. 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 guide layer 10 can be appropriately set according to the application. The thickness of the light guide layer 10 is, for example, 0.05 mm or higher and 50 mm or lower.

[0058] 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 even more preferably 20 μm or more and 80 μm or less. The refractive index of each substrate layer is independent, preferably 1.40 or more and 1.70 or less, and even more preferably 1.43 or more and 1.65 or less.

[0059] The thicknesses of adhesive layers 52, 54, 55, 56, and 58 are each independent, 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 indices of adhesive layers 52, 54, 55, 56, and 58 are each independent, preferably 1.42 to 1.60, and more preferably 1.47 to 1.58. Furthermore, the refractive indices of adhesive layers 52, 54, 56, and 58 are preferably close to the refractive indices of the light guide layer 10 or the shaping film 62A or 62B to which they are connected, and the absolute value of the difference in refractive indices is preferably 0.2 or less.

[0060] The adhesive layer 54 is preferably bonded to the recesses 64A or 64B on the surface of the shaped film 62A or 62B without filling them. As a suitable adhesive for forming the adhesive layer 54, the adhesives described in the applicant's international applications PCT / JP2021 / 006452, PCT / JP2021 / 006453, or Japanese Patent Application No. 2021-025496 are preferred. All disclosures of these applications are incorporated herein by reference. In particular, the polyester-based adhesive described in Japanese Patent Application No. 2021-025496 is preferred.

[0061] The refractive index nL1 of the low refractive index layers 20A and 20B is independent, preferably 1.30 or less, more preferably 1.20 or less, and even more preferably 1.15 or less. The low refractive index layers 20A and 20B are preferably solid, and their refractive index is preferably 1.05 or more. The difference between the refractive index of the light guide layer 10 and the refractive index of the low refractive index layers 20A and 20B is preferably 0.20 or more, more preferably 0.23 or more, and even more preferably 0.25 or more. The low refractive index layers 20A and 20B with a refractive index of 1.30 or less can be formed using porous materials, for example. The thickness of the low refractive index layers 20A and 20B is independent, for example 0.3 μm or more and 5 μm or less.

[0062] When the low-refractive-index layer is a porous material with internal voids, its porosity is preferably 35% by volume or more, more preferably 38% by volume or more, and even more preferably 40% by volume or more. Within this range, a low-refractive-index layer with particularly low refractive index can be formed. The upper limit of the porosity of the low-refractive-index layer is, for example, 90% by volume or less, preferably 75% by volume or less. Within this range, a low-refractive-index layer with excellent strength can be formed. The porosity is calculated using the Lorentz-Lorenz formula based on the refractive index value measured by an ellipsometer.

[0063] Regarding low refractive index, for example, a low refractive index layer with voids disclosed in Patent Document 3 can be used. All disclosures of Patent Document 3 are incorporated herein by reference. Specifically, the low refractive index layer with voids includes generally spherical particles such as silica particles, silica particles with micropores, and hollow silica nanoparticles, fibrous particles such as cellulose nanofibers, alumina nanofibers, and silica nanofibers, and plate-shaped particles such as bentonite nanoclay. In one embodiment, the low refractive index layer with voids is a porous body formed by direct chemical bonding of particles (e.g., microporous particles). Furthermore, at least a portion of the particles constituting the low refractive index layer with voids are bonded together by a small amount (e.g., less than the mass of the particles) of a binder component. The porosity and refractive index of the low refractive index can be adjusted according to the particle size and particle size distribution of the particles constituting the low refractive index layer.

[0064] As a method for obtaining a low refractive index layer with voids, for example, the methods described in Japanese Patent Application Publication No. 2010-189212, Japanese Patent Application Publication No. 2008-040171, Japanese Patent Application Publication No. 2006-011175, International Publication No. 2004 / 113966, and the like are cited in this specification. All disclosures of Japanese Patent Application Publication No. 2010-189212, Japanese Patent Application Publication No. 2008-040171, Japanese Patent Application Publication No. 2006-011175, and International Publication No. 2004 / 113966 are incorporated herein by reference.

[0065] Silica porous bodies are preferred as low-refractive-index layers with porosity. Silica porous bodies can be manufactured, for example, by the following methods: methods involving the hydrolysis and recrystallization of at least one of silicates, water-soluble silanes and / or silsesquioxanes, and their partially water-soluble products and dehydration condensates; methods using porous particles and / or hollow microparticles; methods utilizing the rebound phenomenon to generate an aerogel layer; and methods using a pulverized gel obtained by a sol-gel method, whereby the pulverized particles (i.e., microporous particles) are chemically bonded together by a catalyst or the like. However, the low-refractive-index layer is not limited to silica porous bodies, and the manufacturing method is not limited to the illustrated methods; any manufacturing method can be used. Similarly, the porous layer is not limited to silica porous bodies, and the manufacturing method is not limited to the illustrated methods; any manufacturing method can be used. Furthermore, silsesquioxanes are silicates with (RSiO1.5, R being a hydrocarbon group) as their basic building blocks. Strictly speaking, although they differ from silica, which has SiO2 as its basic building block, they share the characteristic of having a network structure formed by cross-linking through silsesquioxane bonds. Therefore, porous bodies containing silsesquioxanes as their basic building blocks are also referred to here as silica porous bodies or silica-based porous bodies.

[0066] Porous silica bodies can be composed of microporous particles of mutually bonded gel-like silica. Examples of microporous particles of gel-like silica include pulverized gel-like silica. Porous silica bodies can be formed, for example, by coating a substrate with a coating liquid containing pulverized gel-like silica. Pulverized gel-like silica can be chemically bonded (e.g., siloxane bonding) through the action of a catalyst, light irradiation, heating, etc.

[0067] The hardness HH1 of the hard coatings 40A and 40B, for example, in terms of pencil hardness H, is preferably H or higher, more preferably 2H or higher, and even more preferably 4H or higher. On the other hand, although there is no particular upper limit to the hardness HH1 of the hard coatings 40A and 40B, in terms of pencil hardness, it is preferably 6H or lower, and even more preferably 5H or lower. The pencil hardness is determined according to the method of "Pencil Hardness Test" in JIS K 5400. The thickness of the hard coatings 40A and 40B is independent, preferably 1 μm or more and 30 μm or less, more preferably 2 μm or more and 20 μm or less, and even more preferably 3 μm or more and 15 μm or less. If the thickness of the hard coatings 40A and 40B is within this range, it has good scratch resistance.

[0068] Hard coatings 40A and 40B can be made of any suitable material as long as they satisfy the characteristics described above. Hard coatings 40A and 40B are, for example, hardened layers of thermosetting resins or ionizing radiation (e.g., visible light, ultraviolet light) hardening resins. Examples of such hardening resins include (meth)acrylate aminocarboxylate, polyester (meth)acrylate, epoxy (meth)acrylate and other acrylates, silicone resins such as polysiloxane, unsaturated polyesters, and epoxy resins. Hard coatings 40A and 40B can be formed, for example, by applying a material containing a solvent and a hardening compound to the surface of a substrate and allowing it to harden. Details of the hard coatings preferred for use as hard coatings 40A and 40B are described, for example, in Japanese Patent Application Publication No. 2011-237789. All disclosures of Japanese Patent Application Publication No. 2011-237789 are incorporated herein by reference.

[0069] Because the sheet-like lighting device of the embodiment of the present invention has a high visible light transmittance, it can be used as a window capable of illumination. For example, it can be used as an illumination window facing inwards, and as a device for emitting light downwards (or upwards) facing outwards. For example, the light emitted to the outside of the window can be used for advertising. [Industrial Applicability]

[0070] The lighting device of the embodiment of the present invention can emit light from two main surfaces facing opposite directions. The lighting device of the embodiment of the present invention can provide new applications. [Simplified Explanation of the Diagram]

[0009] Figure 1 is a schematic cross-sectional view of the lighting device 100A according to an embodiment of the present invention. Figure 2 is a schematic top view of the lighting device 100A. Figure 3A is a schematic cross-sectional view of the internal space 64A that the lighting device 100A may have. Figure 3B is a schematic top view of the internal space 64A. Figure 3C is a schematic top view showing changes in the internal space 64A. Figure 4 is a diagram showing an example of the curved surface shape of the first inclined surface ISa of the internal space 64A. Figure 5 is a diagram showing a coordinate system for representing the light distribution of the emitted light from the lighting device. Figure 6A is a diagram showing the light distribution of the emitted light from the lighting device of Embodiment 1 according to the present invention. Figure 6B is a diagram showing the light distribution of the emitted light in the V direction from the lighting device of Embodiment 1. Figure 6C is a diagram showing the light distribution of the emitted light in the L direction from the lighting device of Embodiment 1. Figure 7A is a diagram showing the light distribution of the light emitted from the lighting device of Embodiment 2 of the present invention. Figure 7B is a graph showing the light distribution of the light emitted from the lighting device of Embodiment 2 in the V direction. Figure 7C is a graph showing the light distribution of the light emitted from the lighting device of Embodiment 2 in the L direction. Figure 8A is a diagram showing the light distribution of the light emitted from the lighting device of Embodiment 3 of the present invention. Figure 8B is a graph showing the light distribution of the light emitted from the lighting device of Embodiment 3 in the V direction. Figure 8C is a graph showing the light distribution of the light emitted from the lighting device of Embodiment 3 in the L direction. Figure 8D is a graph showing the light distribution of the light emitted from the lighting device of Embodiment 4 of the present invention in the V direction. Figure 9 is a graph showing the result of obtaining the value of the intensity of the first principal ray / the intensity of the second principal ray by simulation when the tilt angle θa of the internal space 64A is changed. Figure 10 is a graph showing the ratio of the intensity of the first principal ray to the intensity of the second principal ray when the tilt angle θa of the internal space 64A of the lighting device of Embodiment 3 is changed, obtained through simulation. Figure 11 is a graph showing the ratio of the intensity of the first principal ray to the intensity of the second principal ray when the tilt angle θb of the internal space 64A of the lighting device of Embodiment 3 is changed, obtained through simulation. Figure 12 is a graph showing the direction (polar angle θ1) of the first principal ray when the tilt angle θa of the internal space 64A of the lighting device of Embodiment 3 is changed. Figure 13 is a graph showing the direction (polar angle θ1) of the first principal ray when the tilt angle θb of the internal space 64A of the lighting device of Embodiment 3 is changed. Figure 14 is a graph showing the direction (polar angle θ2) of the second principal ray when the tilt angle θa of the internal space 64A of the lighting device of Embodiment 3 is changed. Figure 15 is a graph showing the direction of the second principal ray (polar angle θ2) when the tilt angle θb of the internal space 64A of the lighting device in Embodiment 3 is changed.Figure 16A is a schematic cross-sectional view of another lighting device 100A1 according to an embodiment of the present invention. Figure 16B is a schematic cross-sectional view of yet another lighting device 100A2 according to an embodiment of the present invention. Figure 16C is a schematic cross-sectional view of yet another lighting device 100A3 according to an embodiment of the present invention. Figure 16D is a schematic cross-sectional view of yet another lighting device 100A4 according to an embodiment of the present invention. Figure 17A is a schematic cross-sectional view of yet another lighting device 100B1 according to an embodiment of the present invention. Figure 17B is a schematic cross-sectional view of yet another lighting device 100B2 according to an embodiment of the present invention. Figure 17C is a schematic cross-sectional view of yet another lighting device 100B3 according to an embodiment of the present invention. Figure 17D is a schematic cross-sectional view of yet another lighting device 100B4 according to an embodiment of the present invention. Figure 18A is a schematic cross-sectional view of yet another lighting device 100A3_1 according to an embodiment of the present invention. Figure 18B is a schematic cross-sectional view of another lighting device 100A3_2 according to an embodiment of the present invention.

Claims

1. A light guide member for a lighting device, having a first emitting surface and a second emitting surface opposite to the first emitting surface, and having: a light guide layer having a first main surface on the side of the first emitting surface and a second main surface on the side of the second emitting surface; The light-receiving portion, located on the light-receiving side of the light-guiding layer on the light source side, receives light emitted from the light source; and the light distribution control structure has a plurality of internal spaces that overlap with the light-guiding layer when viewed from the normal direction of the first main surface of the light-guiding layer; and each of the plurality of internal spaces has a first inclined surface that, by total internal reflection, causes a portion of the light transmitted within the light-guiding layer to face the first emission surface side, and a second inclined surface opposite to the first inclined surface; and the light guide member for the lighting device is configured such that, by means of the light distribution control structure, a first light with a first light distribution is emitted from the first emission surface, and a second light with a second light distribution is emitted from the second emission surface; the light distribution control structure is formed on a direction conversion layer, which is disposed on the first main surface side or the second main surface side of the light-guiding layer.

2. The light guide member for the lighting device as claimed in claim 1, wherein when the light with the highest intensity in the first light distribution is designated as the first principal light ray and the light with the highest intensity in the second light distribution is designated as the second principal light ray, the ratio of the intensity of the first principal light ray to the intensity of the second principal light ray is in the range of 1:4 or more and 4:1 or less.

3. The light guide member for the lighting device as claimed in claim 2, wherein the intensity of the first main light ray / the intensity of the second main light ray is in the range of 0.5 or more and 1.3 or less.

4. The light guide member for the lighting device as claimed in claim 2, wherein the polar angle θ1 between the first principal ray and the normal relative to the first emitting surface is smaller than the polar angle θ2 between the second principal ray and the normal relative to the second emitting surface.

5. The light guide member for the lighting device as claimed in claim 4, wherein the polar angle θ1 is 0° or more but less than 40°, and the polar angle θ2 is 30° or more but less than 70°.

6. The light guide member for the lighting device as claimed in any of claims 2 to 5, wherein the half-value angle of the light guiding direction of the light guide layer of the first main ray is 67° or less.

7. The light guide member for the lighting device as claimed in any of claims 2 to 5, wherein the half-value angle of the light guiding direction of the light guide layer of the first main ray is 24° or more.

8. The light guide member for the lighting device as claimed in any of claims 1 to 5, wherein the tilt angle θa of the first tilted surface is 10° or more and 70° or less.

9. The light guide member for the lighting device as claimed in any of claims 1 to 5, wherein the tilt angle θb of the second tilted surface is 50° or more and 100° or less.

10. The light guide member for the lighting device according to any one of claims 1 to 5, wherein when viewed from the normal direction relative to the first main surface of the light guide layer, the area of ​​the plurality of internal spaces occupies 80% or less of the area of ​​the light guide layer.

11. A light guide member for an illumination device as claimed in any of claims 1 to 5, wherein the plurality of internal spaces are discretely arranged in the light guiding direction of the light guide layer and in directions intersecting the light guiding direction.

12. A light guide member for an illumination device as claimed in any of claims 1 to 5, wherein, when viewed from the normal direction relative to the first main surface of the light guide layer, the first inclined surface is formed with a curved surface that protrudes toward the light-receiving portion.

13. The light guide component for the lighting device, as requested in any of items 1 to 5, has a visible light transmittance of 60% or more and a turbidity value of less than 30%.

14. A lighting device comprising: a light guide member for a lighting device as claimed in any one of claims 1 to 13; and the light source emitting light toward the light-receiving portion.

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