Lighting device, and task light

Abstract

This lighting device includes a light source and a light guide member, wherein: the light guide member includes a light guide plate having a first main surface and a second main surface on the opposite side to the first main surface, and a first optical laminated body which is disposed on the first main surface side or the second main surface side and which includes a direction converting layer; the direction converting layer includes a plurality of internal spaces having a first inclined surface for orienting light in an emission direction by means of total internal reflection; and the light guide plate has a side surface substantially perpendicular to the first main surface, and an inclined side surface which causes light propagating through the light guide plate to be reflected in the emission direction.

Description

Lighting fixtures and task lights

[0001] The present invention relates to a lighting device, and more particularly to a sheet-like lighting device and task light that include a light source and a light guide plate. Here, the term "sheet-like" is used to mean a plate-like or film-like shape, regardless of the rigidity (flexibility) and thickness of the sheet.

[0002] 2. Description of the Related Art Sheet-shaped lighting devices including a light source and a light guide plate are used, for example, as backlights or frontlights for liquid crystal display devices. Task lights using sheet-shaped lighting devices are also known.

[0003] For example, Patent Document 1 discloses a task light equipped with a light guide plate and a prism sheet. Meanwhile, Patent Documents 2 to 5 disclose sheet-like lighting devices having a light distribution structure that utilizes total reflection at the interface of an air cavity (internal space). The disclosures of Patent Documents 2 to 5 are incorporated herein by reference in their entirety.

[0004] JP 2015-2138 A International Publication No. 2019 / 182091 International Publication No. 2019 / 146628 International Publication No. 2011 / 124765 International Publication No. 2019 / 087118

[0005] The task light described in Patent Document 1 uses a prism sheet, so the work area cannot be seen through the sheet-like lighting device.

[0006] An object of the present invention is to provide a lighting device and a task light that are suitable for use as a task light, allowing a work area to be viewed through the sheet-like lighting device.

[0007] According to embodiments of the present invention, the following solutions are provided: [Item 1] An illumination device comprising: a light source; and a light guide member having a light receiving portion into which light from the light source is incident, wherein the light guide member comprises: a light guide plate having a first main surface and a second main surface opposite to the first main surface; and a first optical stack including a direction changing layer arranged on the first main surface side or the second main surface side, wherein the direction changing layer has a plurality of internal spaces having first inclined surfaces that direct light in an output direction by total internal reflection, and the light guide plate has a first side surface that is substantially perpendicular to the first main surface and an inclined second side surface that reflects light propagating within the light guide plate in the output direction. [Item 2] An illumination device comprising: a light source; and a light guide member having a light receiving portion into which light from the light source is incident, wherein the light guide member comprises: a light guide plate having a first main surface and a second main surface opposite to the first main surface; and a first optical stack including a direction changing layer arranged on the first main surface side or the second main surface side, wherein the direction changing layer has a plurality of internal spaces having first inclined surfaces that direct light in an output direction by total internal reflection, and a side surface of the light guide plate has a curved surface that is concave with respect to the light receiving portion when viewed from a direction normal to the first main surface and includes a first side surface that is approximately perpendicular to the first main surface. [Item 3] The illumination device according to item 2, wherein the light guide plate has a through hole, and the light guide member has the light receiving portion around the through hole. [Item 4] The lighting device according to item 3, wherein, when viewed from a direction normal to the first main surface of the light guide plate, an axis including a central axis of the through hole and a side surface of the light guide plate having the longest distance from the central axis is defined as a long axis of the light guide plate, and among the side surfaces intersecting the long axis, one having a shorter distance from the central axis is defined as a near side surface and one having a longer distance from the central axis is defined as a far side surface, and the first side surface includes the near side surface. [Item 5] The lighting device according to item 4, wherein the shortest distance between the near side surface and the light receiving unit is one-third or less of the distance between the near side surface and the far side surface. [Item 6] The lighting device according to any one of items 2 to 5, wherein the first side surface includes a portion having a parabolic shape when viewed from a direction normal to the first main surface.[Item 7] An illumination device comprising: a light source; and a light guide member having a light receiving unit into which light from the light source is incident, wherein the light guide member comprises: a light guide plate having a first main surface and a second main surface opposite to the first main surface; and a first optical laminate including a direction changing layer arranged on the first main surface side or the second main surface side, wherein the direction changing layer has a plurality of internal spaces having first inclined surfaces that direct light in an output direction by total internal reflection, the plurality of internal spaces being discretely arranged in a light guiding direction of the light guide plate and a direction intersecting the light guiding direction, and comprising a first internal space in which the first inclined surfaces form a curved surface that is convex in a direction facing the light receiving unit when viewed from a direction normal to the first main surface of the light guide plate. [Item 8] An illumination device comprising: a light source; and a light guide member having a light receiving portion into which light from the light source is incident, wherein the light guide member comprises: a light guide plate having a first main surface and a second main surface opposite the first main surface; and a first optical stack including a direction changing layer arranged on the first main surface side or the second main surface side, wherein the direction changing layer has a plurality of internal spaces having first inclined surfaces that direct light in an output direction by total internal reflection, the light receiving portion of the light guide member does not have the direction changing layer on the first main surface and / or second main surface side of the light guide plate, and the light source is arranged to emit light toward the first main surface and / or the second main surface of the light guide plate in the light receiving portion. [Item 9] The illumination device according to item 8, wherein the light guide plate has a step in the light receiving portion, forming a recess that accommodates the light source.[Item 10] The lighting device according to any one of Items 1 to 9, wherein the light guide plate has a through hole, the light guide member has the light receiving portion around the through hole, and a side surface of the light guide plate has a curved surface that is concave with respect to the light receiving portion when viewed from a direction normal to the first main surface, and the side surface has a first side surface that is approximately perpendicular to the first main surface and an inclined second side surface that reflects light propagating within the light guide plate in the emission direction, and when an axis including a central axis of the through hole and a side surface of the light guide plate that is farthest from the central axis when viewed from a direction normal to the first main surface of the light guide plate, is defined as a long axis of the light guide plate, and when one of the side surfaces that intersect with the long axis has a shorter distance from the central axis as a near side surface and a longer distance as a far side surface, the first side surface includes the near side surface and the second side surface includes the far side surface. [Item 11] The lighting device according to Item 10, wherein the side surface of the light guide plate has a side surface between the near side surface and the far side surface, the side surface having an inclination angle greater than the inclination angle of the far side surface and smaller than the inclination angle of the near side surface. [Item 12] The lighting device according to Item 10 or 11, wherein, when viewed from a direction normal to the first main surface of the light guide plate, a region of the light guide member closer to the far side than the light receiving unit is defined as a front region, a region of the light guide member closer to the near side than the light receiving unit is defined as a rear region, and a region between the front region and the rear region is defined as a lateral region, a front internal space present in the front region among the plurality of internal spaces includes a first internal space in which the first inclined surface forms a convex curved surface in a direction facing the light receiving unit. [Item 13] The lighting device according to Item 12, wherein a rear internal space present in the rear region among the plurality of internal spaces forms a convex curved surface in the same direction as the front internal space. [Item 14] The lighting device according to item 12, wherein a rear internal space present in the rear region among the plurality of internal spaces forms a curved surface that is convex in the opposite direction to the front internal space. [Item 15] The lighting device according to any one of items 12 to 14, wherein the light guide plate has an oval shape when viewed from the normal direction to the first main surface. [Item 16] The lighting device according to any one of items 12 to 15, wherein a ratio of an area of ​​the front internal space to an area of ​​the front region when viewed from the normal direction to the first main surface of the light guide plate is 50% or less.[Item 17] The lighting device according to any one of items 12 to 16, wherein the visible light transmittance in the front region is 60% or more and the haze value is less than 30%. [Item 18] The lighting device according to any one of items 1 to 17, wherein the inclination angle of the first inclined surface is 20° or more and 50° or less. [Item 19] The lighting device according to item 17, wherein the plurality of internal spaces have second inclined surfaces opposite to the first inclined surfaces, and the inclination angle of the second inclined surfaces is 70° or more and 90° or less. [Item 20] A task light comprising the lighting device according to any one of items 1 to 19.

[0008] According to an embodiment of the present invention, a lighting device and a task light suitable for use as a task light that allows a work area to be viewed through the sheet-like lighting device are provided. Also, according to an embodiment of the present invention, a novel lighting device and a task light with rich design features are provided.

[0009] 1 is a schematic perspective view of a task light 1000 including a lighting device 100 according to an embodiment of the present invention. FIG. 2 is a plan view showing an example of an illumination area IA by the task light 1000. FIG. 3 is a schematic cross-sectional view of a light-guiding member 100G_A suitable as a light-guiding member 100G of the lighting device 100. FIG. 4 is a schematic cross-sectional view of a light-guiding member 100G_B suitable as a light-guiding member 100G of the lighting device 100. FIG. 5 is a schematic plan view of a light-guiding member 100G_A. FIG. 6 is a schematic plan view of a light-guiding member 100G_AS. FIG. 7 is a schematic cross-sectional view of a light-guiding member 100G_A and a light-guiding member 100G_AS. FIG. 8 is a schematic cross-sectional view of an internal space 64. FIG. 9 is a schematic plan view of the internal space 64. FIG. 10 is a schematic plan view showing variations of the internal space 64. FIG. 11 is a schematic side view of a light source unit 200A. FIG. 12 is a schematic plan view of a light source unit 200A. FIG. 13 is a schematic side view of a light source unit 200B. 1 is a schematic side view of a light source unit 200C. FIG. 2 is a schematic cross-sectional view of a light guide member 100G_Aa. FIG. 3 is a schematic cross-sectional view of a light guide member 100G_Ab. FIG. 4 is a schematic plan view of a light guide member 100G_Ac. FIG. 5 is a schematic cross-sectional view of a light guide member 100G_Ac. FIG. 6 is a schematic cross-sectional view of a light guide member 100G_A1. FIG. 7 is a schematic cross-sectional view of a light guide member 100G_A2. FIG. 8 is a schematic cross-sectional view of a light guide member 100G_A3. FIG. 9 is a schematic cross-sectional view of a light guide member 100G_A4. FIG. 10 is a schematic cross-sectional view of a light guide member 100G_B1. FIG. 11 is a schematic cross-sectional view of a light guide member 100G_B2. FIG. 12 is a schematic cross-sectional view of a light guide member 100G_B3. FIG. 13 is a schematic cross-sectional view of a light guide member 100G_B4.

[0010] Hereinafter, a lighting device and a task light including the same according to an embodiment of the present invention will be described with reference to the drawings. The lighting device according to the embodiment of the present invention is not limited to the following example.

[0011] The lighting device according to the embodiment of the present invention has various features that make it suitable for use as a task light. First, Fig. 1 shows a schematic perspective view of a task light 1000 that includes a lighting device 100 according to the embodiment of the present invention.

[0012] The task light 1000 shown in Fig. 1 includes a sheet-like lighting device 100 and a support 1200. The lighting device 100 includes a light guide member 100G and a light source unit 200, which is housed inside the support 1200. A power source, a switch, and the like are housed inside the support 1200. In the task light 1000, the height of the light exit surface of the lighting device 100 is approximately 360 mm, the length of the lighting device 100 is approximately 350 mm, and the width is approximately 200 mm.

[0013] The task light 1000 is placed, for example, on a table. The light entering the light guide member 100G from the light source unit 200 is emitted downward (emitted light LR in FIG. 1 ), illuminating an illumination area IA shown in FIG. 2 . The illumination area IA is, for example, an area with an illuminance of 400 lux or more. As described below, the light guide member 100G has a light distribution control structure with multiple internal spaces, and has, for example, a visible light transmittance of 60% or more and a haze value of less than 30%. Therefore, a work area (e.g., an object to be observed, such as a document) within the illumination area IA can be viewed from above the light guide member 100G through the light guide member 100G.

[0014] As described below, the light guide member 100G includes a light guide plate 10 and optical stacks 10ts and / or 10bs on two opposing main surfaces of the light guide plate 10 (see, for example, FIG. 7A ). For simplicity, the term "optical stack" may also refer to a single layer. The light guide plate 10 included in the light guide member 100G has an oval shape when viewed normal to the main surface. Here, the term "oval" includes ellipses (long circles), egg shapes, and similar shapes surrounded by curves, as well as shapes obtained by adding two parallel lines to a curved shape or a circle, such as a rounded rectangle. The light guide plate 10 is not limited to these shapes and may have various planar shapes (e.g., circles, rectangles (including squares, polygons)). The light guide plate 10 can have various planar shapes, thereby enhancing the design of the lighting device 100 and task light 1000.

[0015] 3A and 3B, examples of light-guiding members suitable as the light-guiding member 100G of the lighting device 100 will be described. Fig. 3A shows a schematic cross-sectional view of a light-guiding member 100G_A, and Fig. 3B shows a schematic cross-sectional view of a light-guiding member 100G_B.

[0016] The light-guiding member 100G_A shown in FIG. 3A includes a light-guiding plate 10 having a first main surface (here, the upper main surface in the figure) and a second main surface opposite the first main surface, and a first optical stack including a light distribution control structure disposed on the first main surface side. The light distribution control structure has multiple internal spaces 64 having first inclined surfaces ISa (see ISa in FIG. 6A ) that direct light toward the output direction by total internal reflection. The multiple internal spaces 64 are formed in a direction-changing layer 60A. Here, the first optical stack includes a direction-changing layer 60A, a low-refractive-index layer 20A, and a hard coat layer 40A and / or an anti-reflection layer 40A. The first inclined surfaces of the internal spaces 64 direct at least a portion of the light propagating within the light-guiding plate 10 downward in the figure and output it. The light-guiding member 100G_A also includes a second optical stack disposed on the second main surface side of the light-guiding plate 10. The second optical laminate has a low refractive index layer 20B and a hard coat layer 40B and / or an antireflection layer 40B.

[0017] 3B differs from light guiding member 100G_A shown in Fig. 3A in that direction conversion layer 60B is formed on the second main surface side of light guiding plate 10. In light guiding member 100G_A and light guiding member 100G_B, low refractive index layer 20A and hard coat layer and / or antireflection layer 40A, and low refractive index layer 20B and hard coat layer and / or antireflection layer 40B are all optional and may be omitted.

[0018] By providing low-refractive index layers 20A and 20B on the light guide plate 10, the optical performance of the light guide member 100G_A and the light guide member 100G_B can be made less susceptible to the condition of their outermost surfaces. In other words, providing low-refractive index layers 20A and 20B forms an interface between the light guide plate 10 and the low-refractive index layers 20A and 20B that can totally reflect light propagating within the light guide plate 10. Therefore, even if defects such as dirt, dents, or scratches exist on the surfaces of the light guide member 100G_A and the light guide member 100G_B, the light propagating within the light guide plate 10 can be prevented from being affected by these defects. Providing hard coat layers 40A and 40B makes the surfaces less susceptible to scratches. The hard coat layers 40A and 40B preferably have a hardness of pencil hardness H or higher. Furthermore, providing anti-reflection layers 40A and 40B can suppress the generation of unwanted reflected light. Specific configurations of light guiding members 100G_A and 100G_B will be described later with reference to Figures 12A to 12D and 13A to 13D. In addition, with regard to the structure and manufacturing method of the light guiding member, the entire disclosure of Japanese Patent Application No. 2021-084593 is incorporated herein by reference.

[0019] Next, examples of the planar shape and arrangement of the internal space 64 and the cross-sectional shape of the light guide plate 10 will be described with reference to Figures 4A, 4B, and 5. Figure 4A shows a schematic plan view of the light guide member 100G_A, and Figure 4B shows a schematic plan view of the light guide member 100G_AS. Figure 5 shows schematic cross-sectional views of the light guide member 100G_A and the light guide member 100G_AS.

[0020] As shown in FIG. 4A , the light guide plate 10 has a through hole 10h, and the light guide member 100G_A has a light receiving portion 10R around the through hole 10h. In the light receiving portion 10R of the light guide member 100G_A illustrated here, the first and second main surfaces of the light guide plate 10 are exposed. As described below with reference to FIG. 7 , the light sources 220a and 220b are arranged to emit light toward the first and second main surfaces of the light guide plate 10 in the light receiving portion 10R. The long axis LA of the light guide plate 10 is defined as the axis including the central axis AX of the through hole 10h and the side surface with the longest distance between the central axis AX and the side surface of the light guide plate 10. The oval shape, for example, has a long axis LA and a short axis SA that are orthogonal to each other. When the light guide plate 10 has a symmetrical planar shape, a symmetrical illumination area IA can be formed (see FIG. 2 ). The oval shape does not have to be symmetrical about the short axis SA. The oval shape may also be symmetrical about the minor axis SA, such as an ellipse (oval).

[0021] The multiple internal spaces 64 are discretely arranged in the light guide direction (Y direction) of the light guide plate 10 and in the direction perpendicular to the light guide direction (X direction), and include a first internal space in which the first inclined surface ISa forms a convex curved surface toward the light receiving unit 10R (or light source) when viewed from the normal direction to the first main surface of the light guide plate 10. The light guide plate 10 illustrated here has a shape symmetrical with respect to the long axis LA, and the light guide direction is a direction parallel to the long axis LA (Y direction). Of course, light entering the light guide plate 10 from the light receiving unit 10R propagates in various directions within the light guide plate 10, but the Y direction parallel to the long axis LA is referred to as the light guide direction, and light having a Y-direction component (non-zero) is said to propagate in the Y direction. The same applies to other directions. In other words, light propagating in the -Y direction includes all light having a -Y-direction component (non-zero).

[0022] Here, the distances between the two points where the long axis LA and the side surface of the light guide plate 10 intersect and the center of the light receiving unit 10R (the central axis AX of the through hole 10h) on the long axis LA are different from each other, and the point on the long axis LA with the shorter distance from the central axis AX is referred to as the near side surface 10NS, and the point with the longer distance from the central axis AX is referred to as the far side surface 10FS. Furthermore, when viewed from the normal direction to the first main surface of the light guide plate 10, the region of the light guide member 100G_A closer to the far side surface 10FS than the light receiving unit 10R (or the light source) is referred to as the front region FR, the region of the light guide member 100G_A closer to the near side surface 10NS than the light receiving unit 10R (or the light source) is referred to as the rear region RR, and the region between the front region FR and the rear region RR is referred to as the lateral region SR.

[0023] The plurality of internal spaces 64 of the light guide member 100G_A all form curved surfaces that are convex in the −Y direction. Therefore, the internal spaces 64 in the front region FR are first internal spaces that form curved surfaces that are convex toward the light receiving unit 10R (or light source), while the internal spaces 64 in the rear region RR are second internal spaces that form curved surfaces that are convex toward the opposite side from the light receiving unit 10R (or light source). The internal spaces 64 in the side regions SR are third internal spaces that form curved surfaces that are convex in a direction that intersects with the direction toward the light receiving unit 10R (or light source).

[0024] Regarding the size of the internal space 64 (length L, width W: see FIGS. 6A and 6B ), 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. From the viewpoint of light extraction efficiency, the height H (see FIG. 6A ) is preferably 1 μm or more and 100 μm or less.

[0025] The multiple internal spaces 64 are discretely arranged, for example, in the light guide direction and in a direction intersecting the light guide direction. The discrete arrangement may or may not have periodicity (regularity) in at least one direction. However, from the viewpoint of mass productivity, it is preferable that the multiple internal spaces 64 are uniformly arranged. For example, in the example shown in FIG. 4A , multiple internal spaces 64 having substantially the same shape and convex curved surfaces in the same direction are discretely and periodically arranged throughout the entire region of the light guide plate 10 in the light guide direction (Y direction) and the direction perpendicular to the light guide direction (X direction). In this case, the pitch Px is preferably, for example, 10 μm or more and 500 μm or less, and the pitch Py is preferably, for example, 10 μm or more and 500 μm or less. The example shown in FIG. 4A further includes internal spaces arranged at a half pitch in each of the Y direction and the X direction.

[0026] Here, the internal spaces 64 are uniformly arranged throughout the entire front region FR, rear region RR, and side region SR. However, this is not limiting and the internal spaces 64 may be arranged at different pitches in the front region FR, rear region RR, and side region SR. Furthermore, as will be described later with reference to FIGS. 8 to 11 , various modifications are possible. For example, the multiple internal spaces 64 of the light-guiding member 100G_Ac, which will be described later with reference to FIG. 10 , have a curved surface that is convex toward the light-receiving unit 10R (or light source) in each of the front region FR, rear region RR, and side region SR. However, it is preferable that at least the internal space 64 in the front region FR that primarily contributes to forming the illumination area IA of the task light 1000 (sometimes referred to as the “front internal space”) is arranged so that the first inclined surface ISa is parallel to the major axis LA and has a curved surface that is convex toward the light-receiving unit 10R (or light source) (first internal space).

[0027] Since the light guide plate 10 can have various planar shapes, the discrete arrangement of the multiple internal spaces 64 can be modified in various ways depending on the planar shape of the light guide plate 10. The multiple internal spaces 64 are preferably discretely arranged in two intersecting directions, one of which is preferably the light guide direction of the light guide plate 10 (e.g., the direction toward the side of the planar shape of the light guide plate that is farthest from the light receiving unit (light source) and is sometimes referred to as the "long axis direction"). Furthermore, the ratio of the area of ​​the internal spaces to the area of ​​the light guide plate (internal space occupation area ratio) is preferably constant from the perspective of mass productivity, but is not limited to this. Since the internal space occupation area ratio is proportional to the number density of the internal spaces when the occupation area of ​​each internal space is the same, it can also be expressed in terms of number density. For example, if the long axis of the light guide plate 10 is long, the amount of light guided along the long axis decreases as the light guide distance increases. To suppress this, the number density of internal spaces may be decreased closer to the light receiving unit and increased farther from the light receiving unit.

[0028] 5, the light guide plate 10 illustrated here has a first side surface 10S1 that is substantially perpendicular to the first main surface and an inclined side surface 10S2 that reflects light propagating within the light guide plate 10 in the output direction. The side surfaces of the light guide plate 10 illustrated here have the first side surface 10S1 in a region that includes the near side surface 10NS, and a second side surface 10S2 in a region that includes the far side surface 10FS. In FIG. 4A, the region near the near side surface 10NS where the outer edges of the first main surface and the second main surface of the light guide plate 10 overlap is the first side surface 10S1, and the region near the far side surface 10FS where the outer edges of the first main surface and the second main surface of the light guide plate 10 are spaced apart is the second side surface 10S2.

[0029] As shown in Figure 5, the first side surface 10S1 reflects light propagating in the -Y direction within the light guide plate 10 toward the Y direction. Light propagating in the -Y direction from the light receiving unit 10R reaches the first side surface 10S1 without being totally internally reflected by the second inclined surface 1Sb of the internal space 64. The light reflected by the first side surface 10S1 propagates in the Y direction, and a portion of the light is totally internally reflected by the first inclined surface ISa of the internal space 64 and directed toward the emission direction (Z direction). The second side surface 10S2 reflects light propagating in the Y direction within the light guide plate 10 from the light receiving unit 10R toward the emission direction (Z direction) (light rays indicated by dashed arrows in Figure 5).

[0030] As shown in FIG. 4A , when viewed from the direction normal to the first main surface of the light guide plate 10, the side surface of the light guide plate 10 illustrated here has a shape entirely surrounded by curves, being approximately elliptical with a major axis LA. The first side surface 10S1 includes a near side surface 10NS that is close to the light receiving unit 10R on the major axis LA. Therefore, when light propagating through the light guide plate 10 from the light receiving unit 10R is reflected by the first side surface 10S1, the light contains a large amount of Y-direction components. For example, when viewed from the direction normal to the first main surface of the light guide plate 10, the first side surface 10S1 has a parabolic shape. When light entering the light guide plate 10 from the light receiving unit 10R is emitted from the focus of the parabola, the light that reaches the first side surface 10S1 is reflected by the first side surface 10S1 and propagates in the Y direction parallel to the major axis LA, according to the well-known principle used in parabolic antennas. 4A , the focal point FP is indicated by a parabola approximating the vicinity of the apex (near side surface 10NS). The focal point FP is closer to the first side surface 10S1 than to the light-receiving unit 10R. The closer the light entering the light guide plate 10 from the light-receiving unit 10R is to the focal point of the parabola, the more efficiently light propagating in the Y direction can be generated. However, if the first side surface 10S1 is a curved surface that is concave with respect to the light-receiving unit 10R, light containing a large component in the Y direction can be generated, thereby improving the light utilization efficiency.

[0031] In this way, the side surface (including the near side surface 10NS) closer to the central axis AX of the through hole 10h, which is the center of the light receiving unit 10R, is designated as the first side surface 10S1, and the side surface (including the far side surface 10FS) farther from the central axis AX of the through hole 10h is designated as the second side surface 10S2, thereby improving light utilization efficiency. In this case, the distance between the central axis AX and the near side surface NS is less than ½ of the length of the major axis LA (the distance between the near side surface NS and the far side surface FS), preferably ⅓ or less, and more preferably ¼ or less. In the example of FIG. 4A , the distance between the central axis AX and the near side surface 10NS is slightly shorter than ¼ of the length of the major axis LA, and the distance between the focal point FP and the near side surface 10NS is slightly shorter than 1 / 10 of the length of the major axis LA. Light enters the light guide plate 10 from the light receiving unit 10R. Since the shortest distance between the light-receiving unit 10R and the near side surface 10NS is shorter than the distance between the central axis AX and the near side surface 10NS, it is preferable that the position of the point of the light-receiving unit 10R closest to the near side surface 10NS satisfies the above condition, and the closer the point of the light-receiving unit 10R closest to the near side surface 10NS is to the focal point FP, the more preferable it is. However, depending on the planar shape of the light guide plate 10, it is not necessarily better to have a larger Y-direction component included in the light reflected by the first side surface 10S1, and therefore the shape of the first side surface 10S1 and the distance between the light-receiving unit 10R and the near side surface 10NS can be adjusted as appropriate.

[0032] The inclination angle of the first side surface 10S1 including the near side surface 10NS is preferably, for example, 80° to 100°. The inclination angle of the second side surface 10S2 including the far side surface 10FS is preferably, for example, 40° to 60°. In this case, the side surfaces of the light guide plate 10 may be configured to have a third side surface between the first side surface 10S1 and the second side surface 10S2, the third side surface having an inclination angle smaller than the inclination angle of the first side surface 10S1 (e.g., approximately 90°) and larger than the inclination angle of the second side surface 10S2 (e.g., approximately 45°). 4A , the distance between the outer edges of the first and second major surfaces of light guide plate 10 is shown to be widest near far side surface 10FS, and the outer edges of the first and second major surfaces are shown overlapping near near side surface 10NS, with the width between the outer edges of the first and second major surfaces continuously narrowing as one approaches from far side surface 10FS to near side surface 10NS. The inclination angles of first side surface 10S1 and second side surface 10S2 may be constant or continuously changeable within the above-mentioned range.

[0033] 4B is a schematic plan view of another light guide member 100G_AS that may be included in the lighting device according to the embodiment of the present invention. The light guide plate 10M included in the light guide member 100G_AS has a planar shape that combines a rectangular shape with an oval shape. As such, the light guide plate included in the lighting device according to the embodiment of the present invention is not limited to an oval shape.

[0034] The light guide plate 10M of the light guide member 100G_AS is rectangular in the front region FR and the side region SR, and approximately elliptical in the rear region RR. The light guide plate 10M in the rear region RR has a first side surface 10S1 including a near side surface 10NS. Therefore, similar to the first side surface 10S1 of the light guide plate 10 of the light guide member 100G_A shown in FIG. 4A , light propagating through the light guide plate 10M from the light receiving unit 10R is reflected by the first side surface 10S1, generating light containing a large Y-direction component. The second side surface 10S2 including the far side surface 10FS has a constant inclination angle along the short side (X-direction) of the rectangle. Along the long side (Y direction) of the rectangle in the front region FR and the side region SR of the light guide plate 10M, there is a third side having an inclination angle smaller than the inclination angle of the first side 10S1 (e.g., approximately 90°) and larger than the inclination angle of the second side 10S2 (e.g., approximately 45°).

[0035] As described above, if the side surface of the light guide plate has a concave curved surface with respect to the light receiving section when viewed from the normal direction to the first main surface and includes a side surface (for example, the above-mentioned first side surface 10S1) that is approximately perpendicular to the first main surface, it is possible to generate light that contains a large amount of components in the Y direction, thereby improving the light utilization efficiency.

[0036] Because light propagating through the light guide plate 10 has a spread in the Y direction (or the −Y direction), the first inclined surface ISa acts uniformly on the light if the first inclined surface ISa has a convex curve toward the light receiving unit 10R (or light source) and toward the side surface (near side surface 10NS) that is substantially perpendicular to the first main surface. Note that if the light propagating through the light guide plate 10 is highly parallel (light with little spread in the Y direction or the −Y direction), the first inclined surface ISa may be parallel to the X direction. Furthermore, instead of the discrete internal spaces 64, for example, an internal space such as a groove extending in the X direction (e.g., a triangular prism) may be used. Furthermore, if the light guide plate 10 is rectangular (with the X direction as the short side), the first inclined surface ISa may be parallel to the X direction, or may be an internal space such as a groove extending in the X direction (e.g., a triangular prism).

[0037] Next, the shape of the internal space 64 will be described with reference to Figures 6A, 6B, and 6C. Figure 6A is a schematic cross-sectional view of the internal space 64, Figure 6B is a schematic plan view of the internal space 64, and Figure 6C is a schematic plan view showing variations of the internal space 64.

[0038] As shown in FIG. 6A , the cross-sectional shape of the internal space 64 is, for example, triangular. The inclination angle θa of the first inclined surface ISa on the light source side (light incident side) is, for example, 10° or more and 70° or less. If the inclination angle θa is less than 10°, the light utilization efficiency may be low, and if it exceeds 70°, processing may be difficult. Furthermore, the inclination angle θb of the second inclined surface ISb opposite the first inclined surface ISa is, for example, 50° or more and 100° or less. If the inclination angle θb is less than 50°, the amount of light directed in undesired directions may increase. Similarly, if it exceeds 100°, the amount of light directed in undesired directions may increase. Furthermore, in order to increase the amount of light emitted from the exit surface and reduce the amount of light emitted toward the viewer, the inclination angle θa of the first inclined surface ISa is preferably, for example, 20° or more and 50° or less, and the inclination angle θb of the second inclined surface ISb is preferably, for example, 70° or more and 90° or less.

[0039] 6B and 6C , in the planar shape of the internal space 64 when viewed from the normal direction to the first main surface of the light guide plate 10, the length L of the internal space 64 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 FIG. 6A ) is preferably 1 μm or more and 100 μm or less. Furthermore, the shape of the curved surface formed by the first inclined surface ISa (the curve formed by the first inclined surface ISa shown in FIG. 6B ) is represented by, for example, a quartic curve.

[0040] Note that depending on the processing accuracy when forming a shaped film having a recess having the planar shape shown in FIG. 6B, a recess having the planar shape shown in FIG. 6C may be formed. For example, as shown in FIG. 6C, the shape of the curved surface formed by the first inclined surface ISa may deviate from the desired curve (e.g., a quartic curve), and / or the plane formed by the second inclined surface ISb may become a curved surface. Even in such cases, as shown in FIG. 6C, the planar shape of the internal space can be characterized by the length L, width W, and curved shape, similar to the planar shape of the internal space shown in FIG. 6B, and substantially the same effects and advantages can be obtained. In particular, since the second inclined surface ISb does not act as an internal total reflection surface, even if it becomes a curved surface as shown in FIG. 6C, the impact on the optical performance of the light-guiding member on the output surface side is small.

[0041] 7A and 7B, a description will be given of the structure of light source unit 200A used as light source unit 200. Fig. 7A is a schematic side view of light source unit 200A in the housing of support 1200 of task light 1000, and Fig. 7B is a schematic plan view of light source unit 200A.

[0042] As shown in Fig. 7A , the light source unit 200A has light sources 220a and 220b supported by support plates 210a and 210b, respectively. The support plates 210a and 210b are fixed to, for example, support columns 1220 of the support body 1200. The light sources 220a and 220b are, for example, LED devices. As shown in Fig. 7B , the light sources 220a and 220b are arranged around the through-hole 10h of the light guide plate 10a of the light guide member 100G1.

[0043] The light guide member 100G1 has a light receiving section 10Ra in which the first and second principal surfaces of the light guide plate 10a are exposed, and the light sources 220a and 220b are arranged to emit light toward the first and second principal surfaces of the light guide plate 10a at the light receiving section 10Ra, as indicated by the arrows in FIG. 7A . The light emitted from the light sources 220a and 220b enters the light guide plate 10a and propagates within the light guide plate 10a by, for example, being totally reflected by the exposed first and second principal surfaces of the light guide plate 10a and the inner surfaces of the through holes 10h. While an example in which the light sources 220a and 220b are arranged toward the first and second principal surfaces of the light guide plate 10a is shown here, only one of the light sources 220a and 220b may be arranged toward one of the principal surfaces.

[0044] Although the light receiving unit 10Ra has an example in which the first and second principal surfaces of the light guide plate 10a are exposed, the light guide member 100G1 may not have a direction conversion layer (e.g., direction conversion layer 60A in FIG. 3A) having a light distribution control structure included in the optical laminate 10ts and / or 10bs. That is, at least one layer, such as a low refractive index layer, a hard coat layer, or an anti-reflection layer, may be present on the first and / or second principal surfaces onto which light from the light source 220a and / or 220b is incident. Furthermore, the first and / or second principal surfaces of the light receiving unit 10Ra onto which light from the light source 220a and / or 220b is incident may be processed to have an uneven surface, or a layer having an uneven surface may be formed on the surface. By making the surface uneven, the incidence efficiency can be improved. The degree of unevenness is, for example, an arithmetic mean roughness Ra of 10 μm or more and 1000 μm or less. Furthermore, such a surface having irregularities can be obtained by processing the surface of the light guide plate 10a by a known method, for example, using a bit, drill, milling cutter, end mill, or the like, or by forming a lens shape such as a prism or lenticular on the surface of the light guide plate 10a by a known method.

[0045] A light source unit 200B shown in Fig. 7C can also be used. Fig. 7C is a schematic side view of the light source unit 200B. The light guide plate 10b of the light source unit 200B has a step at the light receiving portion 10Rb, forming a recess that can accommodate the light source unit 200B. By adopting such a configuration, the thickness of the lighting device can be reduced.

[0046] Furthermore, a light source unit 200C shown in FIG. 7D can also be used. FIG. 7D is a schematic side view of the light source unit 200C. Instead of arranging the light sources 220a and / or 220b so as to emit light toward the first and / or second principal surfaces of the light guide plate 10c as shown in FIG. 7D, the light source 220 can be arranged within the through-hole 10hc of the light guide plate 10c so as to emit light toward the inner surface of the through-hole 10hc. However, if the light source 220 is arranged so that light is incident from the side of the light guide plate 10c, unevenness in the intensity of the light propagating within the light guide plate 10c can occur, and bright streaks of light can be seen when viewed from the normal direction to the principal surface of the light guide plate 10c. This is thought to be due to the influence of the discretely arranged internal spaces 64. As shown in Figures 7A and 7C, by arranging the light sources 220a and / or 220b so that they emit light toward the first principal surface and / or the second principal surface of the light guide plates 10a, 10b, it is possible to suppress or prevent the above-mentioned bright light streaks from appearing.

[0047] Next, modified examples of the light-guiding member 100G_A will be described with reference to Fig. 8 to Fig. 11. Fig. 8 is a schematic cross-sectional view of a light-guiding member 100G_Aa, Fig. 9 is a schematic cross-sectional view of a light-guiding member 100G_Ab, Fig. 10 is a schematic plan view of a light-guiding member 100G_Ac, and Fig. 11 is a schematic cross-sectional view of the light-guiding member 100G_Ac.

[0048] The light-guiding member 100G_Aa shown in Fig. 8 differs from the light-guiding member 100G_A in that both the near-side surface 10NS and the far-side surface 10FS of the light-guiding plate 10Aa are side surfaces that are substantially perpendicular to the first main surface. The light-guiding member 100G_Ab shown in Fig. 9 differs from the light-guiding member 100G_A in that both the near-side surface 10NS and the far-side surface 10FS of the light-guiding plate 10Ab are inclined side surfaces that reflect light propagating within the light-guiding plate 10Ab in the output direction.

[0049] The light-guiding member 100G_Ac shown in FIGS. 10 and 11 differs from the light-guiding member 100G_Ab shown in FIG. 9 in that it includes a direction-changing layer 60Ac with a different internal space 64 arrangement. The internal spaces 64 of the direction-changing layer 60Ac have convex curved surfaces facing the light-receiving unit 10R (or light source) in each of the front region FR, rear region RR, and side region SR, and all of the internal spaces 64 are first internal spaces. That is, as shown in FIG. 11 , the rear internal space 64 in the rear region RR forms a convex curved surface in the opposite direction to the front internal space 64 in the front region FR. Therefore, the rear internal space 64 in the rear region RR directs a portion of the light propagating within the light guide plate 10Ab toward the output direction. The side internal spaces 64 in the side regions SR similarly direct a portion of the light propagating within the light guide plate 10Ab toward the output direction.

[0050] The light guide member 100G_A has the advantage of being able to utilize a larger amount of light in the front region FR than the light guide members 100G_Aa, 100G_Ab, and 100G_Ac. Furthermore, the light guide member's direction-changing layer 60A has an internal space 64 uniformly distributed throughout the entire front region FR, rear region RR, and side region SR. Therefore, the light guide member 100G_A or a portion including the direction-changing layer can be efficiently formed using, for example, a roll-to-roll method or a roll-to-sheet method. The optical laminate (including the direction-changing layer) attached to the light guide plate 10 can also be divided into regions. It is also possible not to form a direction-changing layer in the rear region RR and / or the side region SR. These may be selected appropriately depending on the application, etc.

[0051] When viewed from the normal direction to the first main surface of the light guide plate 10 of the light guide member 100G included in the lighting device 100 according to the embodiment of the present invention, the ratio of the area of ​​the internal space 64 present in the front region FR to the area of ​​the front region FR is preferably 80% or less. Of course, the ratio of the area of ​​the internal space 64 present in the rear region RR and / or the side region SR is also preferably 80% or less. The ratio of the area of ​​the internal space 64 to the area of ​​the light guide plate 10 (occupancy rate) is preferably 1% or more and 80% or less in each region, with the upper limit being more preferably 50% or less, and even more preferably 45% or less. To obtain high transmittance and / or a low haze value, the ratio is preferably 30% or less, more preferably 10% or less, and even more preferably 5% or less.

[0052] The visible light transmittance of at least the front region FR of the light guide member 100G is preferably 60% or more, and more preferably 70% or more. The haze value is preferably less than 10%, and more preferably 5% or less.

[0053] The light-guiding member 100G included in the lighting device 100 according to the embodiment of the present invention is not limited to the above example and can be modified in various ways. The light-guiding member 100G_A1, the light-guiding member 100G_A2, the light-guiding member 100G_A3, and the light-guiding member 100G_A4 shown in Figures 12A, 12B, 12C, and 12D are examples of light-guiding members that have a direction-changing layer 60A on the first main surface (upper side) of the light-guiding plate 10, similar to the light-guiding member 100G_A shown in Figure 3A.

[0054] 12A is composed of a shaped film 62A having recesses 64A on the surface of a direction conversion layer 60A of the light guide member 100G_A, and an adhesive layer 54. The light guide member 100G_A does not have the low refractive index layers 20A and 20B and the hard coat layer and / or antireflection layer 40B of the light guide member 100G_A.

[0055] The light-guiding member 100G_A2 shown in FIG. 12B has a low-refractive index layer 20A on a direction-changing layer 60A. The low-refractive index layer 20A acts to prevent light leakage when fingerprints or other stains adhere to the surface. Alternatively, as in the light-guiding member 100G_A3 shown in FIG. 12C, a low-refractive index layer 20B may be provided on the second main surface (lower side) of the light-guiding plate 10. Furthermore, as in the light-guiding member 100G_A4 shown in FIG. 12D, a low-refractive index layer 20A may be provided on the direction-changing layer 60A, and a low-refractive index layer 20B may be provided on the second main surface (lower side) of the light-guiding plate 10. When providing the anti-reflection layer / hard coat layer and the low-refractive index layer, adhesive layers 52, 55, 56, and 58 may be provided as needed.

[0056] Next, light-guiding member 100G_B1, light-guiding member 100G_B2, light-guiding member 100G_B3, and light-guiding member 100G_B4 shown in Figures 13A, 13B, 13C, and 13D are examples of light-guiding members that have a direction-changing layer 60B on the second main surface (lower side) of light-guiding plate 10, similar to light-guiding member 100G_B shown in Figure 3B.

[0057] 13A is composed of a shaped film 62B having recesses 64B on the surface of a direction conversion layer 60B of the light guide member 100G_B, and an adhesive layer 54. The light guide member 100G_B does not have the low refractive index layers 20A and 20B and the hard coat layer and / or the antireflection layer 40A of the light guide member 100G_B.

[0058] The light-guiding member 100G_B2 shown in FIG. 13B further includes a low-refractive index layer 20B below the direction-changing layer 60B. The low-refractive index layer 20B acts to prevent light leakage when fingerprints or other stains adhere to the surface. Alternatively, as in the light-guiding member 100G_B3 shown in FIG. 13C, a low-refractive index layer 20A may be provided on the first main surface (upper side) of the light-guiding plate 10. Furthermore, as in the light-guiding member 100G_B4 shown in FIG. 13D, a low-refractive index layer 20A may be provided on the direction-changing layer 60B and a low-refractive index layer 20A may be provided on the first main surface (upper side) of the light-guiding plate 10.

[0059] Although not shown in Figures 12A to 12D and 13A to 13D, the low refractive index layers 20A, 20B and the hard coat layer and / or antireflection layer 40A, 40B each have a substrate layer on the adhesive layer side. The substrate layer serves to support the low refractive index layer and the hard coat layer and / or antireflection layer, respectively. The thickness of each substrate layer is independently, 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 independently, for example, 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.

[0060] A preferred example of each component of the lighting device according to the embodiment of the present invention will be described.

[0061] The shaped film for forming the internal space can be manufactured, for example, as follows. A textured film was manufactured according to the method described in JP-A-2013-524288. Specifically, the surface of a polymethyl methacrylate (PMMA) film was coated with lacquer (Finecure RM-64 manufactured by Sanyo Chemical Industries, Ltd.), an optical pattern was embossed on the film surface containing the lacquer, and then the lacquer was cured to manufacture the desired textured film. The total thickness of the textured film is, for example, 130 μm.

[0062] The light guide plate 10 is made of a known material with high transmittance for visible light. For example, the light guide plate 10 is made of an acrylic resin such as polymethyl methacrylate (PMMA), a polycarbonate (PC) resin, a cycloolefin resin, or glass (for example, quartz glass, alkali-free glass, or borosilicate glass). The refractive index n of the light guide plate 10 is ＧＰ is, for example, 1.40 or more and 1.80 or less. Unless otherwise specified, the refractive index refers to a refractive index measured with an ellipsometer at a wavelength of 550 nm. The thickness of the light guide plate 10 can be set appropriately depending on the application. The thickness of the light guide plate 10 is, for example, 0.05 mm or more and 50 mm or less.

[0063] The thicknesses of the adhesive layers 52, 54, 55, 56, and 58 are each independently, for example, from 0.1 μm to 100 μm, preferably from 0.3 μm to 100 μm, and more preferably from 0.5 μm to 50 μm. The refractive indexes of the adhesive layers 52, 54, 55, 56, and 58 are each independently preferably from 1.42 to 1.60, and more preferably from 1.47 to 1.58. The refractive indexes of the adhesive layers 52, 54, 56, and 58 are preferably close to the refractive index of the light guide plate 10 or the shaping film 62A or 62B to which they are in contact, and the absolute value of the difference in refractive index is preferably 0.2 or less.

[0064] The adhesive layer 54 can preferably be bonded without filling the recesses 64A or 64B on the surface of the shaped film 62A or 62B. Suitable adhesives for forming the adhesive layer 54 include those disclosed in International Application PCT / JP2021 / 006452, International Application PCT / JP2021 / 006453, or Japanese Patent Application No. 2021-025496 filed by the present applicant. The entire 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.

[0065] The refractive index n of the low refractive index layers 20A and 20B Ｌ１ are each independently, for example, 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, 20B are preferably solid, and the refractive index is, for example, preferably 1.05 or more. The difference between the refractive index of the light guide plate 10 and the refractive index of the low refractive index layers 20A, 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, 20B, which have a refractive index of 1.30 or less, can be formed using, for example, a porous material. The thickness of the low refractive index layers 20A, 20B is each independently, for example, 0.3 μm or more and 5 μm or less.

[0066] When the low refractive index layer is a porous material having voids therein, the porosity is preferably 35 vol% or more, more preferably 38 vol% or more, and particularly preferably 40 vol% or more. Within this range, a low refractive index layer with a particularly low refractive index can be formed. The upper limit of the porosity of the low refractive index layer is, for example, 90 vol% or less, preferably 75 vol% or less. Within this range, a low refractive index layer with excellent strength can be formed. The porosity is a value calculated from the refractive index measured with an ellipsometer using the Lorentz-Lorenz formula.

[0067] The low-refractive index layer may be, for example, a voided low-refractive index layer as disclosed in Patent Document 3. The entire disclosure of Patent Document 3 is incorporated herein by reference. Specifically, the voided low-refractive index layer may include substantially spherical particles such as silica particles, microporous silica particles, hollow silica nanoparticles, fibrous particles such as cellulose nanofibers, alumina nanofibers, and silica nanofibers, and flat particles such as nanoclay composed of bentonite. In one embodiment, the voided low-refractive index layer is a porous body formed by direct chemical bonding of particles (e.g., microporous particles). Furthermore, at least some of the particles constituting the voided low-refractive index layer may be bonded to each other via a small amount (e.g., less than the mass of the particles) of a single binder component. The porosity and refractive index of the low-refractive index layer can be adjusted by the particle size, particle size distribution, etc. of the particles constituting the low-refractive index layer.

[0068] Methods for obtaining a low refractive index layer having voids include, for example, methods described in JP 2010-189212 A, JP 2008-040171 A, JP 2006-011175 A, WO 2004 / 113966 A, and references thereto. The disclosures of JP 2010-189212 A, JP 2008-040171 A, JP 2006-011175 A, and WO 2004 / 113966 A are incorporated herein by reference in their entirety.

[0069] A porous silica body can be suitably used as the low refractive index layer having voids. The porous silica body can be produced by, for example, the following methods. Examples include a method of hydrolyzing and polycondensing a silicon compound; hydrolyzable silanes and / or silsesquioxane, and at least one of their partial hydrolyzates and dehydration condensates; a method using porous particles and / or hollow microparticles; a method of producing an aerogel layer by utilizing the springback phenomenon; and a method using a pulverized gel in which a gel-like silicon compound obtained by a sol-gel method is pulverized and the resulting pulverized microporous particles are chemically bonded together with a catalyst or the like. However, the low refractive index layer is not limited to a porous silica body, and the production method is not limited to the exemplified methods, and any production method may be used. However, the porous layer is not limited to a porous silica body, and the production method is not limited to the exemplified methods, and any production method may be used. The silsesquioxane may be (RSiO １．５ , R is a hydrocarbon group) as a basic structural unit, and ２ Although it is strictly different from silica, which has silsesquioxane as a basic structural unit, it has something in common with silica in that it has a network structure cross-linked by siloxane bonds. Therefore, in this specification, porous materials containing silsesquioxane as a basic structural unit are also referred to as porous silica materials or silica-based porous materials.

[0070] The porous silica material can be composed of microporous particles of a gel-like silicon compound bonded to one another. Examples of the microporous particles of the gel-like silicon compound include pulverized gel-like silicon compounds. The porous silica material can be formed, for example, by applying a coating liquid containing pulverized gel-like silicon compounds to a substrate. The pulverized gel-like silicon compounds can be chemically bonded (e.g., siloxane bonded) by, for example, the action of a catalyst, light irradiation, heating, etc.

[0071] Hardness H of hard coat layers 40A and 40B Ｈ1 The hardness H of the hard coat layers 40A and 40B is preferably H or more, more preferably 2H or more, and even more preferably 4H or more, in terms of pencil hardness. Ｈ1Although there is no particular upper limit, the pencil hardness is preferably 6H or less, more preferably 5H or less. The pencil hardness is measured by a method in accordance with JIS K 5400 "Pencil Hardness Test." The thicknesses of the hard coat layers 40A and 40B are each independently 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. When the thicknesses of the hard coat layers 40A and 40B are within such ranges, they have good scratch resistance.

[0072] The hard coat layers 40A, 40B can be made of any suitable material as long as they satisfy the above-mentioned characteristics. The hard coat layers 40A, 40B are, for example, cured layers of a thermosetting resin or an ionizing radiation (e.g., visible light, ultraviolet) curable resin. Examples of such curable resins include acrylates such as urethane (meth)acrylate, polyester (meth)acrylate, and epoxy (meth)acrylate, silicon resins such as polysiloxane, unsaturated polyester, and epoxy resin. The hard coat layers 40A, 40B can be formed, for example, by applying a material containing a solvent and a curable compound to the surface of the target substrate and curing it. Details of hard coat layers suitable for use as the hard coat layers 40A, 40B are described, for example, in JP 2011-237789 A. The entire disclosure of JP 2011-237789 A is incorporated herein by reference.

[0073] The task light 1000 shown in FIG. 1 has, for example, the following configuration.

[0074] The light guide member has the structure shown in Figures 4A and 13D. Light guide plate 10: acrylic plate with a thickness of 5 mm Shape-transfer film 62A: thickness 100 μm Recess 64A: L = 80 μm, W = 20 μm, H = 10 μm First inclined surface: curved surface (quartic curve), inclination angle θa = 30° Second inclined surface: flat surface (straight line), inclination angle θb = 70° Arrangement shown in Figure 4A, pitch Px = 200 μm, pitch Py = 100 μm Occupancy area ratio 5% Low refractive index layers 20A, 20B: thickness 1 μm, refractive index 1.18 Hard coat layers 40A, 40B: thickness 5 μm, pencil hardness 3H

[0075] The light guide member has a visible light transmittance of 80% and a haze value of 5%.

[0076] The light source unit has the structure shown in Figures 7A and 7B. LED device: NF2W757GT-MT (12 pieces) manufactured by Nichia Corporation. Light receiving section 10R: diameter 50 mm, through hole 10h: diameter 10.5 mm

[0077] As described above, the present invention provides a sheet-like lighting device that allows the user to see the work area and provides a task light with sufficient illuminance. Furthermore, the present invention also provides lighting devices with a variety of unique shapes, such as an oval shape, that are highly aesthetically pleasing.

[0078] Although the illumination device having one light receiving unit (light source or light source unit) has been illustrated here, two or more light receiving units may be provided. For example, in an illumination device having an elliptical light guide member such as the light guide member 100G_A shown in FIG. 4A, two light receiving units may be provided on the major axis symmetrical with respect to the minor axis. In this case, an internal space having the above-described convex curved surface may be provided for each of the light receiving units.

[0079] The lighting device according to the embodiment of the present invention is suitable for use as a task light, for example.

[0080] 10: Light guide plate, 64: Internal space, 20A, 20B: Low refractive index layer, 40A, 40B: Hard coat layer and / or anti-reflection layer, 60A, 60B: Direction conversion layer, 100: Lighting device, 100G: Light guide member, 200: Light source unit

Claims

1. A lighting device comprising a light source and a light guide member having a light receiving portion into which light from the light source is incident, wherein the light guide member comprises a light guide plate having a first main surface and a second main surface opposite to the first main surface, and a first optical laminate including a direction conversion layer disposed on the first main surface side or the second main surface side, wherein the direction conversion layer has a plurality of internal spaces each having a first inclined surface that directs light in the emission direction by total internal reflection, and the light guide plate has a first side surface substantially perpendicular to the first main surface and an inclined second side surface that reflects light propagating in the light guide plate in the emission direction.

2. A lighting device comprising a light source and a light guide member having a light receiving portion into which light from the light source is incident, wherein the light guide member comprises a light guide plate having a first main surface and a second main surface opposite to the first main surface, and a first optical laminate including a direction conversion layer disposed on the first main surface side or the second main surface side, wherein the direction conversion layer has a plurality of internal spaces each having a first inclined surface that directs light in the emission direction by total internal reflection, and the side surface of the light guide plate has a concave curved surface with respect to the light receiving portion when viewed from the normal direction to the first main surface, and includes a first side surface substantially perpendicular to the first main surface.

3. The light guide plate has a through hole, and the light guide member has the light receiving portion around the through hole. The lighting device according to claim 2.

4. When viewed from the normal direction to the first main surface of the light guide plate, an axis including the central axis of the through hole and the side surface having the longest distance between the central axis and the side surface of the light guide plate is defined as the major axis of the light guide plate. Among the side surfaces intersecting the major axis, when the side surface with the shorter distance from the central axis is defined as the near side surface and the side surface with the longer distance is defined as the far side surface, the first side surface includes the near side surface. The lighting device according to claim 3.

5. The shortest distance between the near side surface and the light receiving portion is 1 / 3 or less of the distance between the near side surface and the far side surface. The lighting device according to claim 4.

6. The first side surface includes a portion having a parabolic shape when viewed from the normal direction to the first main surface. The lighting device according to any one of claims 2 to 5.

7. A lighting device comprising a light source and a light guide member having a light receiving portion into which light from the light source is incident, wherein the light guide member comprises a light guide plate having a first main surface and a second main surface opposite to the first main surface, and a first optical laminate including a direction conversion layer disposed on the first main surface side or the second main surface side, The direction conversion layer has a plurality of internal spaces having a first inclined surface that directs light in the emission direction by total internal reflection. The plurality of internal spaces are discretely arranged in the light guiding direction of the light guide plate and in a direction intersecting the light guiding direction. When viewed from the normal direction of the first main surface of the light guide plate, the first inclined surface forms a curved surface convex in the direction facing the light receiving portion. The lighting device includes a first internal space. **Claim 8** A lighting device having a light source and a light guide member having a light receiving portion into which light from the light source is incident. The light guide member has a light guide plate having a first main surface and a second main surface opposite to the first main surface, and a first optical laminate including a direction conversion layer disposed on the first main surface side or the second main surface side. The direction conversion layer has a plurality of internal spaces having a first inclined surface that directs light in the emission direction by total internal reflection. The light receiving portion of the light guide member does not have the direction conversion layer on the first main surface and / or the second main surface side of the light guide plate. The light source is disposed so as to emit light toward the first main surface and / or the second main surface of the light guide plate at the light receiving portion. The lighting device. **Claim 9** The lighting device according to claim 8, wherein the light guide plate has a step at the light receiving portion and forms a recess for accommodating the light source. **Claim 10** The light guide plate has a through hole. The light guide member has the light receiving portion around the through hole. When viewed from the normal direction of the first main surface of the light guide plate, the side surface of the light guide plate has a curved surface concave with respect to the light receiving portion, and a first side surface substantially perpendicular to the first main surface and a second side surface inclined to reflect light propagating in the light guide plate in the emission direction. When viewed from the normal direction of the first main surface of the light guide plate, an axis including the central axis of the through hole and the side surface having the longest distance between the central axis and the side surface of the light guide plate is defined as the major axis of the light guide plate. Among the side surfaces intersecting the major axis, when the side surface with the shorter distance from the central axis is defined as the near side surface and the side surface with the longer distance is defined as the far side surface, the first side surface includes the near side surface, and the second side surface includes the far side surface. The lighting device according to any one of claims 1 to 4 and 7 to 9. **Claim 11** The lighting device according to claim 10, wherein the side surface of the light guide plate has a side surface having an inclination angle greater than the inclination angle of the far side surface and smaller than the inclination angle of the near side surface between the near side surface and the far side surface. **Claim 12** When viewed from the normal direction to the first major surface of the light guide plate, a region of the light guide member on the far side surface side of the light receiving portion is defined as a front region, a region of the light guide member on the near side surface side of the light receiving portion is defined as a rear region, and when a region between the front region and the rear region is defined as a side region, The illumination device according to claim 10, wherein a front internal space existing in the front region among the plurality of internal spaces includes a first internal space in which the first inclined surface forms a curved surface convex in a direction facing the light receiving portion.

13. The illumination device according to claim 12, wherein a rear internal space existing in the rear region among the plurality of internal spaces forms a curved surface convex in the same direction as the front internal space.

14. The illumination device according to claim 12, wherein a rear internal space existing in the rear region among the plurality of internal spaces forms a curved surface convex in a direction opposite to that of the front internal space.

15. The illumination device according to claim 12, wherein the light guide plate has an oval shape when viewed from the normal direction to the first major surface.

16. The illumination device according to claim 12, wherein a ratio of an area of the front internal space to an area of the front region when viewed from the normal direction to the first major surface of the light guide plate is 50% or less.

17. The illumination device according to claim 12, wherein a visible light transmittance in the front region is 60% or more and a haze value is less than 30%.

18. The illumination device according to any one of claims 1 to 4 and 7 to 9, wherein an inclination angle of the first inclined surface is 20° or more and 50° or less.

19. The illumination device according to claim 17, wherein the plurality of internal spaces have a second inclined surface on a side opposite to the first inclined surface, and an inclination angle of the second inclined surface is 70° or more and 90° or less.

20. A task light including the illumination device according to any one of claims 1 to 4 and 7 to 9.