Light guide plate and lighting device

Abstract

The present invention provides a light guide plate and lighting device capable of reducing brightness unevenness on the illuminated surface. [Solution] The light guide plate 30 comprises a main surface 31, a light emitting surface 32 facing the main surface 31 and emitting light, and a light incident surface 33. The main surface 31 is provided with a plurality of elongated prisms 37 that intersect with the first direction (X-axis direction) and whose longitudinal direction is the second direction (Y-axis direction) along the main surface 31. Each elongated prism 37 has a control surface 37a that reflects light to the light emitting surface 32. When the region where elongated prisms 37 exist on any first virtual straight line L1 extending along the second direction is defined as the prism region R1, within the prism region R1, the control surface 37a exists on any first virtual straight line L1 in the region R2 between the control surface 37a1 of the elongated prism 371 located at the end of the first direction and the control surface 37a2 of the elongated prism 372 located at the end in the direction opposite to the first direction.

Description

Technical Field

[0001] The present invention relates to a light guide plate and a lighting device.

Background Art

[0002] A lighting device including a light guide plate is known. For example, Patent Document 1 discloses a lighting device including a light guide plate having an incident light end face which is an end face on which a light source is disposed, and an emission surface which emits light incident from the incident light end face. In this lighting device, a large number of hemispherical dots are arranged on the back surface facing the emission surface of the light guide plate. The dots adjust the optical path so that the light reflected on the back surface of the light guide plate is emitted from the emission surface of the light guide plate.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present invention provides a light guide plate and a lighting device capable of reducing luminance unevenness on an irradiation surface.

Means for Solving the Problems

[0005] A light guide plate according to one aspect of the present invention comprises a main surface, a light emitting surface facing the main surface and emitting light, and a side end surface in a first direction along the main surface and the light emitting surface, to which light emitted from a light source is incident, wherein the main surface is provided with a plurality of elongated prisms intersecting the first direction and having a second direction along the main surface as its longitudinal direction, and the elongated prism has a control surface that reflects light traveling from the light incident surface in the direction opposite to the first direction to the light emitting surface, and extends along the second direction. If the region in which the long prism exists on any of the first virtual straight lines, and in which a plurality of the long prisms exist on at least one second virtual straight line extending along the first direction, then within the prism region, in the region between the control surface of the long prism located at the end in the first direction and the control surface of the long prism located at the end in the direction opposite to the first direction, the control surface exists on any of the first virtual straight lines.

[0006] A lighting device according to one aspect of the present invention comprises the above-mentioned light guide plate, the light source facing the light incident surface of the light guide plate, and an opposing member having an opposing surface facing the light emission surface of the light guide plate, wherein the edge of the opposing surface in the direction opposite to the first direction is a straight line extending along the second direction, and a light passage space is formed between the opposite end of the light guide plate and the opposing member through which light emitted from the light emission surface passes. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a light guide plate and an illumination device that can reduce brightness unevenness on the illuminated surface. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is an external view of a lighting device according to one embodiment of the present invention. [Figure 2] Figure 2 is an end view showing the structure of the lighting device. [Figure 3] Figure 3 shows the light source and light guide plate of the lighting device from the Z-axis direction. [Figure 4] Figure 4 is an enlarged view of section A in Figure 2. [Figure 5] Figure 5 is an enlarged view showing another example of part A in Figure 2. [Figure 6] Figure 6 shows the arrangement of long prisms in the light guide plate according to a comparative example. [Figure 7] Figure 7 is an end view showing a lighting device using a light guide plate according to a comparative example. [Figure 8] Figure 8 shows the structure of the light guide plate according to the first modification. [Figure 9] Figure 9 shows the structure of the light guide plate according to the second modification. [Figure 10] Figure 10 shows the structure of the light guide plate according to the third modification. [Figure 11] Figure 11 shows the structure of the light guide plate according to the fourth modification. [Figure 12] Figure 12 shows the structure of the light guide plate according to the fifth modified example. [Figure 13] Figure 13 shows the structure of the light guide plate according to the sixth modification. [Figure 14] Figure 14 is a plan view showing the structure of multiple grids in the light guide plate according to the seventh modified example. [Figure 15] Figure 15 is a plan view showing the structure of multiple grids in the light guide plate according to the eighth modified example. [Figure 16] Figure 16 is a plan view showing the structure of the grid included in the light guide plate according to the eighth modified example. [Figure 17] Figure 17 is an end view showing the structure of the lighting device according to the ninth modified example. [Figure 18] Figure 18 is an end view showing the structure of the lighting device according to the 10th modified example. [Figure 19] Figure 19 is an end view showing the structure of the lighting device according to the 11th modified example. [Figure 20] Figure 20 shows the structure of the opposing member of the lighting device according to the 12th modified example. [Figure 21]FIG. 21 is a diagram showing the structure of the opposing member of the lighting device according to the 12th modification example. [Figure 22] FIG. 22 is a diagram showing the structure of the light source of the lighting device according to the 13th modification example. [Figure 23] FIG. 23 is an end view showing the structure of the lighting device according to the 14th modification example.

Mode for Carrying Out the Invention

[0009] (Background of the Invention) Prior to the description of the embodiments of the present invention and the like, the background of the present invention will be described.

[0010] In a configuration in which hemispherical dots are provided on the main surface facing the light emitting surface of the light guide plate and the light is reflected by the dots to the light emitting surface, like the lighting device described in Patent Document 1, it is difficult to obtain a wide light distribution in the direction in which the light incident surface extends.

[0011] In order to obtain a wide light distribution, the inventors of the present application considered providing a plurality of long prisms on the main surface of the light guide plate with the direction in which the light incident surface extends as the longitudinal direction.

[0012] However, when long prisms with the direction in which the light incident surface extends as the longitudinal direction are provided on the light guide plate, while a wide light distribution can be obtained, it has been found that luminance unevenness occurs on the irradiation surface where the light is irradiated.

[0013] Therefore, as a result of intensive studies, the inventors of the present application have created a light guide plate and a lighting device capable of reducing luminance unevenness on the irradiation surface.

[0014] Embodiments of the present invention will be described below with reference to the drawings. The embodiments described below are all general or specific examples. The numerical values, shapes, materials, components, arrangement positions of components, and connection configurations shown in the following embodiments are examples only and are not intended to limit the present invention. Furthermore, among the components in the following embodiments, those not described in the independent claim representing the highest-level concept will be described as optional components.

[0015] Furthermore, each figure is a schematic diagram and not necessarily a strictly accurate representation. In addition, in each figure, substantially identical components are denoted by the same reference numeral, and redundant explanations may be omitted or simplified. Also, in the embodiments described below, the term "identical" does not mean strictly identical, but rather substantially identical. Substantially identical means identical in scope, including, for example, manufacturing tolerances and dimensional tolerances.

[0016] Furthermore, in the drawings used to illustrate the following embodiments, coordinate axes may be indicated. The Z-axis direction is described as the thickness direction of the light guide plate. The X-axis and Y-axis directions are mutually orthogonal directions on a plane perpendicular to the Z-axis direction. In the following embodiments, a plan view means a view from the Z-axis direction.

[0017] (Embodiment) [Lighting equipment] The following describes a lighting device according to an embodiment. Figure 1 is an external view of a lighting device 10 according to one embodiment of the present invention.

[0018] As shown in Figure 1, the lighting device 10 according to this embodiment is, for example, a lighting device embedded in a wall surface 91 and illuminating the floor surface 92 with light. Alternatively, the lighting device 10 may be embedded in a wall surface 91 and illuminating the ceiling surface. Furthermore, the lighting device 10 may be embedded in a ceiling surface or floor surface 92 and illuminating the wall surface 91 with light. Also, the lighting device 10 does not necessarily have to be embedded in a wall surface 91, ceiling surface, or floor surface 92. In this embodiment, the lighting device 10 may be placed either indoors or outdoors.

[0019] Next, the internal structure of the lighting device 10 of this embodiment will be described. Figure 2 is an end view showing the structure of the lighting device 10. Figure 3 is a view showing the light source 20 and light guide plate 30 of the lighting device 10 from the Z-axis direction. In Figure 3, hatching has been applied to the control surface 37a, which will be described later, for ease of understanding.

[0020] As shown in Figure 2, the lighting device 10 comprises a light source 20, a light guide plate 30, an opposing member 40, and a housing 60.

[0021] As shown in Figures 2 and 3, the light source 20 faces the light guide plate 30 and emits light toward the light guide plate 30. The light source 20 is, for example, a light-emitting module having a substrate 21 and a plurality of light-emitting elements 22.

[0022] The substrate 21 is, for example, a long rectangular substrate that is elongated in the Y-axis direction. The longitudinal direction of the substrate 21 is the Y-axis direction, and the short direction of the substrate 21 is the Z-axis direction. The thickness direction of the substrate 21 is the X-axis direction. The substrate 21 is arranged parallel to the light incident surface 33 of the light guide plate 30, which will be described later. The shape of the substrate 21 is not particularly limited.

[0023] The substrate 21 is a rigid substrate such as a resin substrate, a ceramic substrate, or a metal-based substrate. The material of the substrate 21 is not particularly limited.

[0024] The substrate 21 has a mounting surface on which multiple light-emitting elements 22 are mounted. The mounting surface of the substrate 21 faces the light incident surface 33 of the light guide plate 30, which will be described later.

[0025] Multiple light-emitting elements 22 are mounted on the mounting surface of the substrate 21. The multiple light-emitting elements 22 are arranged in a row along the longitudinal direction (in this case, the Y-axis direction) of the substrate 21.

[0026] The light-emitting element 22 is, for example, an LED element that emits light. Furthermore, the light-emitting element 22 is, for example, a surface-mount device (SMD) type LED element. The light-emitting element 22 emits, for example, incandescent to daylight-colored light (color temperature between 2600K and 7100K) toward the light incident surface 33 of the light guide plate 30 located in front of the light-emitting element 22 (details to be described later).

[0027] The light source 20 is electrically connected to a power supply circuit (not shown) inside the housing 60 by a cable (not shown), and emits light using power supplied from the power supply circuit.

[0028] The light guide plate 30 guides light. Specifically, the light guide plate 30 is a flat light guide. The light guide plate 30 has a rectangular shape when viewed from the Z-axis direction (the thickness direction of the light guide plate 30). The light guide plate 30 is a transparent material, but any light-transmitting material is acceptable. The light guide plate 30 is formed from, for example, acrylic resin, but may also be formed from polycarbonate resin or glass.

[0029] The light guide plate 30 has a main surface 31, a light emitting surface 32, a light incident surface 33, a first side end surface 34, a second side end surface 35, and a third side end surface 36.

[0030] The main surface 31 is a surface perpendicular to the thickness direction (Z-axis direction) of the light guide plate 30. The main surface 31 has approximately the same area as, for example, the light emission surface 32, and has a larger area than the other surfaces (light incident surface 33, first side end surface 34, second side end surface 35, and third side end surface 36).

[0031] Multiple elongated prisms 37 are provided on the main surface 31, with the longitudinal direction being a second direction intersecting the first direction. The first direction is the direction along the main surface 31 and the light emission surface 32, and is the direction from the center of the light guide plate 30 toward the light incident surface 33. In this embodiment, the first direction is the X-axis direction. The second direction is the direction along the main surface 31 and the light emission surface 32, and is the direction intersecting (in this case, perpendicular to) the first direction. In this embodiment, the second direction is the Y-axis direction.

[0032] The long prism 37 reflects the light traveling through the light guide plate 30 toward the light emitting surface 32. In the diagram, the long prism 37 is shown large for ease of understanding, but in reality, it is very small. The length of the long prism 37 in the longitudinal direction (second direction) is, for example, about 4 mm. The long prism 37 will be discussed later.

[0033] The light-emitting surface 32 faces the main surface 31. The light-emitting surface 32 is positioned parallel to the main surface 31. The light-emitting surface 32 also emits light. Specifically, the light-emitting surface 32 transmits the light reflected by the long prism 37 and emits it to the outside of the light guide plate 30.

[0034] The light incident surface 33 is the side end surface of the light guide plate 30 in the first direction, along the main surface 31 and the light emission surface 32. The light incident surface 33 is formed to extend along the second direction (Y-axis direction). A light source 20 is positioned opposite the light incident surface 33, and light emitted from the light source 20 is incident on it.

[0035] The first side end face 34 is the side end face of the light guide plate 30 in the direction opposite to the first direction (to the left in Figure 2). In other words, the first side end face 34 faces the light incident surface 33 in the direction along the first direction.

[0036] The second side end face 35 and the third side end face 36 are side end faces of the light guide plate 30 located on both sides in the direction along the Y-axis. The second side end face 35 and the third side end face 36 are formed to extend along the first direction (X-axis direction).

[0037] Here, we will explain the long prism 37. Figure 4 is an enlarged view of section A in Figure 2. Figure 5 is an enlarged view showing another example of section A in Figure 2.

[0038] As shown in Figure 4, in this embodiment, the long prism 37 of the light guide plate 30 is a groove having a substantially V-shape in cross-sectional view. Each long prism 37 has a control surface 37a and a non-control surface 37b. The control surface 37a reflects light that is incident on the light incident surface 33 and propagating in the opposite direction to the first direction (X-axis direction) toward the light emission surface 32. In this embodiment, each of the control surface 37a and the non-control surface 37b is substantially a plane and is an inclined surface that is inclined with respect to the main surface 31. Furthermore, the control surface 37a is formed on the light incident surface 33 side (light source 20 side) of the long prism 37, and the non-control surface 37b is formed on the first end face 34 side (opposite side from the light source 20) of the long prism 37.

[0039] In Figure 4, the main surface 31, control surface 37a, and uncontrollable surface 37b are depicted as planes, but the main surface 31, control surface 37a, and uncontrollable surface 37b only need to be substantially flat. Specifically, for example, as shown in Figure 5, the portion of the main surface 31 that forms the edge of the long prism 37 may be raised, for example, so as to protrude in the direction opposite to the light-emitting surface 32. Also, the control surface 37a and uncontrollable surface 37b do not need to be formed in a strictly straight line in cross-sectional view. Furthermore, the connection portion between the control surface 37a and the uncontrollable surface 37b may be pointed or not (rounded). In this way, by not having a perfect plane for the main surface 31, control surface 37a, and uncontrollable surface 37b, and by not having a pointed connection portion between the control surface 37a and the uncontrollable surface 37b, the illumination surface (floor surface 92 in this embodiment) illuminated by the lighting device 10 can be illuminated with soft light.

[0040] If the angle between the control surface 37a and the main surface 31 is defined as the control angle θ1, then the control angle θ1 is, for example, between 1° and 70°. In this embodiment, the control angle θ1 of all long prisms 37 is the same. However, the control angles θ1 of all long prisms 37 do not have to be the same; they may be different from each other. The long prisms 37 are formed, for example, by laser processing, cutting, or injection molding. However, when the long prisms 37 are formed by thermal processing such as laser processing, the long prisms 37 tend to have shapes in which the main surface 31, control surface 37a, and non-control surface 37b are not perfectly flat, or the connection between the control surface 37a and the non-control surface 37b is not pointed, as shown in Figure 5.

[0041] The long prism 37 of this embodiment has a larger control surface area 37a (side surface on the light source 20 side) compared to a conical prism, resulting in higher light control efficiency and superior light distribution control. The long prism 37 makes it possible to efficiently achieve wide light distribution characteristics in the second direction (Y-axis direction).

[0042] In this embodiment, the elongated prism 37 is a recess provided on the main surface 31, but it may also be a convex portion. If the elongated prism 37 is a convex portion provided on the main surface 31, the control surface 37a is formed on the first end surface 34 side (opposite side from the light source 20) of the elongated prism 37, and the non-control surface 37b is formed on the light incident surface 33 side (light source 20 side) of the elongated prism 37.

[0043] In this embodiment, as shown in Figure 3, the light guide plate 30 has one or more (in this case, two) prism regions R1 (regions enclosed by thick lines). The prism region R1 is the region where the long prism 37 exists on any of the first virtual straight lines L1 extending along the second direction. In other words, within the prism region R1, there is no first virtual straight line L1 that does not pass through the long prism 37 in a plan view. To put it another way, when the prism region R1 is viewed from the second direction (Y-axis direction), the long prism 37 exists at any position in the first direction.

[0044] Furthermore, the prism region R1 is a region where multiple long prisms 37 exist on at least one second virtual straight line L2 extending along the first direction. In other words, when the prism region R1 is viewed from the first direction, multiple long prisms 37 exist at any position in the second direction.

[0045] Furthermore, in this embodiment, within the prism region R2, from the control surface 37a1 of the long prism 377 closest to the light source 20 at the end of the long prism 371 located in the first direction (X-axis direction) to the control surface 37a2 of the long prism 372 (the long prism 37 furthest from the light source 20) located at the end in the opposite direction to the first direction, a control surface 37a exists on any of the first virtual lines L1. In other words, within region R2, there is no first virtual line L1 that does not pass through the control surface 37a in a plan view. To put it another way, when region R2 is viewed from a second direction, a control surface 37a exists at any position in the first direction.

[0046] Next, the opposing member 40 will be described. As shown in Figure 2, the opposing member 40 is positioned to face the light-emitting surface 32 of the light guide plate 30. In this embodiment, the opposing member 40 has the function of blocking light. In other words, the surface of the opposing member 40 is formed of a material with low light reflectivity. For example, the opposing member 40 may be entirely formed of a material with low reflectivity, or it may be formed by painting or coating a material with low reflectivity onto the surface of a substrate made of resin or metal.

[0047] The opposing member 40 has an opposing surface 41 that faces the light-emitting surface 32. In this embodiment, light emitted from the light-emitting surface 32 reaches the opposing surface 41. The opposing member 40 is, for example, a planar member that extends in a first direction and a second direction. The opposing surface 41 has, for example, a substantially rectangular shape in plan view. The edge 41a of the opposing surface 41 in the direction opposite to the first direction is a straight line extending along the second direction (Y-axis direction).

[0048] Between the end of the light guide plate 30 in the direction opposite to the first direction and the opposing member 40, a light-passing space S is formed through which light emitted from the light-emitting surface 32 passes. Therefore, most of the light emitted from the light-emitting surface 32 and reaching the opposing surface 41 of the opposing member 40 is absorbed by the opposing surface 41 and does not emit outside from the lighting device 10. On the other hand, light emitted from the light-emitting surface 32 in the direction opposite to the first direction (to the left in Figure 2) from the edge 41a is emitted outside the lighting device 10 through the light-passing space S and illuminates, for example, the floor surface 92.

[0049] In this embodiment, the opposing surface 41 is inclined with respect to the light-emitting surface 32 such that the distance between the opposing surface 41 and the light-emitting surface 32 increases in the direction opposite to the first direction. The opposing surface 41 may be arranged parallel to the light-emitting surface 32. Alternatively, the opposing surface 41 may be inclined with respect to the light-emitting surface 32 such that the distance between the opposing surface 41 and the light-emitting surface 32 decreases in the direction opposite to the first direction.

[0050] Furthermore, in this embodiment, the opposing member 40 has a non-opposing surface 42 that does not face the light-emitting surface 32 of the light guide plate 30. The non-opposing surface 42 extends diagonally downward from the edge 41a of the opposing surface 41 and is exposed to the outside of the lighting device 10.

[0051] Next, the housing 60 will be described. The housing 60 holds the light source unit, which includes the light source 20 and the light guide plate 30, and the opposing member 40. In this embodiment, the housing 60 is housed in a recess provided in the wall surface 91. The light source unit may also include, in addition to the light source 20 and the light guide plate 30, a reflector facing the main surface 31 of the light guide plate 30, and / or a holding member for holding the light source 20 and the light guide plate 30. The housing 60 also constitutes the outer casing of the lighting device 10. The housing 60 is formed of, for example, a metal material, but may also be formed of a resin material.

[0052] [Effects of arranging long prisms] In this embodiment, by arranging the long prism 37 within the prism region R1 as described above, brightness unevenness can be reduced on the illuminated surface (floor surface 92 in this embodiment) that is illuminated by the lighting device 10. The reason why brightness unevenness is reduced will be explained below by comparing the light guide plate 30 according to this embodiment with the light guide plate 130 according to the comparative example. Figure 6 is a diagram showing the arrangement of the long prism 37 in the light guide plate 130 according to the comparative example.

[0053] As described above, in this embodiment, if the region where the long prism 37 exists on any of the first virtual lines L1 is defined as the prism region R1, then in the region R2 of the prism region R1, from the control surface 37a1 of the long prism 371 located at the end of the first direction (towards the light source 20) to the control surface 37a2 of the long prism 372 located at the end in the opposite direction (opposite to the light source 20), the control surface 37a exists on any of the first virtual lines L1. In other words, multiple long prisms 37 are arranged slightly offset in the X-axis direction.

[0054] On the other hand, as shown in Figure 6, in the comparative example light guide plate 130, all the long prisms 37 are aligned in the first direction (X-axis direction) and the second direction (Y-axis direction). Note that alignment in a certain direction means that they are arranged in a row in a certain direction without shifting in a direction perpendicular to that direction.

[0055] Specifically, the light guide plate 130 is provided with multiple prism groups 131, each consisting of multiple (in this case, eight) long prisms 37 arranged linearly in a second direction (in this case, six groups). The multiple prism groups 131 are arranged at a predetermined pitch in the first direction.

[0056] Multiple (in this case, eight) elongated prisms 37 included in one prism group 131 are arranged in the same position in the first direction. In other words, in the light guide plate 130 of the comparative example, unlike the light guide plate 30 of this embodiment, the multiple elongated prisms 37 are not shifted in the first direction (X-axis direction).

[0057] Let's consider the case where this light guide plate 130 is replaced with the light guide plate 30 of the lighting device 10. Figure 7 is an end view showing a lighting device using the light guide plate 130 according to a comparative example.

[0058] As shown in Figure 7, the floor surface 92 has a bright area R110 reached by light reflected by the long prism 37 and passing near the edge 41a of the opposing member 40, and a dark area R120 adjacent to area R110 on the light source 20 side. Area R120 is darker than area R110 because the light is blocked by the edge 41a of the opposing member 40.

[0059] Here, the edge 41a of the opposing member 40 extends linearly in the second direction (Y-axis direction), and in the light guide plate 130 of the comparative example, the multiple (eight in this case) long prisms 37 are arranged linearly in the second direction and are not shifted in the first direction (X-axis direction), so each of the portions R110 and R120 is formed linearly in the second direction. Consequently, streaky brightness unevenness extending in the second direction occurs on the floor surface 92.

[0060] In contrast, in the light guide plate 30 of this embodiment, a control surface 37a exists on any of the first virtual lines L1 in region R2 of the prism region R1. In other words, multiple long prisms 37 are arranged slightly offset in the first direction (X-axis direction). Therefore, as shown in Figure 2, the bright portion R10 reached by light reflected by the long prisms 37 and passing near the edge 41a of the opposing member 40 is less likely to be formed linearly in the second direction. Similarly, the dark portion R20 adjacent to the light source 20 side of portion R10 is also less likely to be formed linearly in the second direction. Consequently, streaky brightness unevenness extending in the second direction is less likely to occur on the floor surface 92.

[0061] Thus, the light guide plate 30 of this embodiment can reduce brightness unevenness on the illuminated surface (floor surface 92) compared to the light guide plate 130.

[0062] [First variation] Next, with reference to Figure 8, a light guide plate 30 according to a first modification of the present invention will be described. Figure 8 is a diagram showing the structure of the light guide plate 30 according to the first modification. In the first modification, unlike the above embodiment, an example is described in which the long prism 37 is aligned in a first direction. Note that in Figure 8 and Figures 9 to 13 described later, hatching is applied to the control surface 37a for ease of understanding.

[0063] As shown in Figure 8, in the first modified example, similar to the above embodiment, the light guide plate 30 has one or more prism regions R1.

[0064] In this first modified example, unlike the light guide plate 30 of the embodiment shown in Figure 3, the multiple long prisms 37 within the prism region R1 are aligned in the first direction (X-axis direction). Specifically, the light guide plate 30 is provided with multiple prism groups 301, each consisting of multiple (in this case, four) long prisms 37 aligned in the first direction. In Figure 8, for example, 10 prism groups 301 are arranged within one prism region R1. Within one prism group 301, the multiple long prisms 37 are arranged at a constant pitch in the first direction. Adjacent long prisms 37 in the first direction may or may not be in contact with each other, as shown in Figure 8.

[0065] Multiple prism groups 301 adjacent to each other in the second direction (Y-axis direction) are arranged at a constant pitch in the second direction. As shown in Figure 8, adjacent prism groups 301 in the second direction may or may not be in contact with each other. Note that adjacent prism groups 301 in the second direction are arranged to be offset from each other in the first direction.

[0066] The other components of the first modified example are the same as those of the embodiment described above.

[0067] As explained above, in the first modified example, the multiple long prisms 37 are aligned in the first direction (X-axis direction) within the prism region R1. This allows more long prisms 37 to be placed within the prism region R1 compared to the case where the multiple long prisms 37 are not aligned in the first direction, as in the light guide plate 30 shown in Figure 3. Therefore, the light emitted from the light source 20 can be efficiently extracted from the light guide plate 30 in a predetermined direction.

[0068] [Second variation] Next, with reference to Figure 9, a light guide plate 30 according to a second modification of the present invention will be described. Figure 9 is a diagram showing the structure of the light guide plate 30 according to the second modification. In the second modification, an example will be described in which multiple grids 302, which are regions in which multiple long prisms 37 are arranged, are provided. Note that "arranged" means arranged in a row.

[0069] As shown in Figure 9, in the second modified example, similar to the above embodiment, the light guide plate 30 has one or more (in this case, two) prism regions R1.

[0070] In this second modification, each prism region R1 is provided with multiple grids 302 (regions enclosed by thick dashed lines) (two grids in this case), which are regions in which multiple (20 in this case) long prisms 37 are arranged in a first direction and a second direction. Within the grid 302, the multiple long prisms 37 are aligned in the first direction.

[0071] Furthermore, each set of grids 302 includes at least two (in this case, two) grids 302a, each containing long prisms 37 arranged in the same configuration. Additionally, each set of grids 302 includes at least two (in this case, two) grids 302b, each containing long prisms 37 arranged in the same configuration. Here, "arranging the long prisms 37 in the same configuration" means that the relative positions of the multiple long prisms 37 included in each grid 302 are the same between the grids 302.

[0072] Furthermore, the two grids 302a are arranged adjacent to each other in the second direction. The two grids 302b are arranged adjacent to each other in the second direction. Grids 302a and 302b are arranged at a predetermined distance from each other in the first direction. In the second modified example, the two grids 302a are arranged in one prism region R1, and the two grids 302b are arranged in another prism region R1. Each grid 302 is composed of multiple (in this case, five) prism groups 301 (see Figure 8) as described in the first modified example. Also, the two grids 302a may be arranged at a predetermined distance from each other in the second direction. Similarly, the two grids 302b may be arranged at a predetermined distance from each other in the second direction. Also, grids 302a and 302b may be arranged adjacent to each other in the first direction.

[0073] In the second modified example, adjacent grids 302 in the second direction are not shifted in the first direction. Also, adjacent grids 302 in the first direction are not shifted in the second direction.

[0074] The other components of the second modified example are the same as those of the embodiments described above.

[0075] As explained above, in the second modified example, the multiple grids 302 include at least two grids 302 in which the long prisms 37 are arranged in the same order. This means that, for example, if the arrangement (relative positional relationship) of the long prisms 37 in one grid 302 is determined, the arrangement of the long prisms 37 in at least one other grid 302 is also determined. Therefore, the time required when designing or modifying the light guide plate 30 can be reduced.

[0076] Furthermore, in the configuration shown in the second modified example, where multiple grids 302 are provided on the light guide plate 30, for example, the control angles of the control surfaces 37a of the long prisms 37 included in each grid 302 may all be the same. In this case, the control angles of the control surfaces 37a may differ for each grid 302.

[0077] [Third variation] Next, with reference to Figure 10, a light guide plate 30 according to a third modification of the present invention will be described. Figure 10 is a diagram showing the structure of the light guide plate 30 according to the third modification. In the third modification, unlike the second modification, an example will be described in which the grids 302, which are arranged in a line in the second direction, are offset in the first direction.

[0078] As shown in Figure 10, in the third modified example, similar to the second modified example, multiple grids 302 (two in this case) are provided in each prism region R1. Also, similar to the second modified example, the light guide plate 30 is provided with two grids 302a and two grids 302b.

[0079] In this third modification, unlike the second modification, the grids 302 arranged in the second direction (Y-axis direction) are offset from each other in the first direction (X-axis direction). Specifically, the centers O1 of the grids 302 arranged in the second direction are located at different positions in the first direction. In other words, the centers O1 of adjacent grids 302 in the second direction are located at different distances from the light source 20.

[0080] The center O1 of the grid 302, which is arranged in the second direction, is not particularly limited, but in the first direction, it is shifted by a distance W1 smaller than the pitch P1 of the long prism 37 in the first direction.

[0081] Furthermore, the distance W1 between the centers O1 of the grids 302 arranged in the second direction may be smaller than the width W2 of the long prism 37 in the first direction. In addition, the distance W1 between the centers O1 of the grids 302 arranged in the second direction may be smaller than the width W3 of the control surface 37a of the long prism 37 in the first direction.

[0082] The other components of the third variant are the same as those of the second variant.

[0083] As explained above, in the third modified example, the centers O1 of the grids 302 arranged side by side in the second direction are positioned at different locations in the first direction. As a result, for example, the long prism 37 of one grid 302 and the long prism 37 of the other grid 302 are offset in the first direction (X-axis direction). Therefore, the portions R10 and R20 caused by the long prism 37 of one grid 302 and the portions R10 and R20 caused by the long prism 37 of the other grid 302 are offset in the first direction. As a result, streaky brightness unevenness extending in the second direction is less likely to occur on the illuminated surface (floor surface 92).

[0084] Furthermore, the center O1 of the grids 302 arranged in the second direction is shifted by a distance W1 in the first direction that is smaller than the pitch P1 of the long prism 37 in the first direction. This makes it easy to shift the portions R10 and R20 caused by the long prism 37 of one grid 302 and the portions R10 and R20 caused by the long prism 37 of the other grid 302 in the first direction.

[0085] [Fourth variation] Next, with reference to Figure 11, a light guide plate 30 according to a fourth modification of the present invention will be described. Figure 11 is a diagram showing the structure of the light guide plate 30 according to the fourth modification. In the fourth modification, unlike the third modification, an example will be described in which the center O1 of the grid 302 is shifted by d / n [mm] in the first direction. This will be explained in detail below.

[0086] As shown in Figure 11, in the fourth modified example, the prism region R1 is provided with multiple grids 302 (three in this case). Within the prism region R1, multiple long prisms 37 are arranged in the first direction at a constant pitch d [mm]. For the sake of clarity in the following explanation, the three grids 302 may be referred to as grids 3021, 3022, and 3023, from left to right in Figure 11.

[0087] In the fourth modified example, similar to the third modified example, adjacent grids 3021 to 3023 in the second direction are arranged to be offset from each other in the first direction.

[0088] In the fourth modified example, when providing n different distances from the light incident surface 33 to the center O1 of a grid 302 in a plurality of grids 302 arranged in a line in the second direction, the centers O1 of the grids 302 are shifted by d / n [mm].

[0089] Specifically, in the fourth modified example, in the multiple grids 302 arranged in a row in the second direction, three different distances are provided for the distance from the light incident surface 33 to the center O1 of the grid 302. In other words, in the multiple grids 302 arranged in a row in the second direction, the distance from the light incident surface 33 to the center O1 of the grid 302 is distributed among n values. In this case, the center O1 of the grid 302 is shifted by d / n [mm]. For example, the long prism 37 of grid 3021 and the long prism 37 of grid 3022 are shifted by d / n [mm] in the first direction. Also, for example, the long prism 37 of grid 3022 and the long prism 37 of grid 3023 are shifted by d / n [mm] in the first direction.

[0090] In the fourth modified example, we described an example where the number of grids 302 included in one prism region R1 is the same as the number of different distances from the light incident surface 33 to the center O1 of the grids 302 (in this case, 3). However, the number of different distances from the light incident surface 33 to the center O1 of the grids 302 may be less than the number of grids 302 included in one prism region R1.

[0091] The other components of the fourth modification are the same as those of the third modification.

[0092] As explained above, in the fourth modified example, when providing n different distances from the light incident surface 33 to the center O1 of a grid 302 in a plurality of grids 302 arranged in a line in the second direction, the centers O1 of the grids 302 are offset by d / n [mm]. As a result, for example, the long prism 37 of grid 3021, the long prism 37 of grid 3022, and the long prism 37 of grid 3023 are offset in the first direction. Therefore, portions R10 and R20 caused by the long prisms 37 of grids 3021, 3022, and 3023 can be easily shifted in the first direction. As a result, streaky brightness unevenness extending in the second direction is further reduced on the illuminated surface (floor surface 92).

[0093] [Fifth variation] Next, with reference to Figure 12, a fifth modification of the present invention, specifically a light guide plate 30, will be described. Figure 12 shows the structure of the light guide plate 30 according to the fifth modification. In the fifth modification, unlike the embodiments described above, an example will be described in which the long prism 37 is arranged symmetrically with respect to a line L10 extending along the first direction.

[0094] As shown in Figure 12, in the fifth modified example, the multiple elongated prisms 37 included in the prism region R1 are arranged symmetrically with respect to a line L10 extending along the first direction. The line L10 does not have to be located at the center of the light guide plate 30 in the Y-axis direction, but in the fifth modified example, it is located at the center of the light guide plate 30 in the Y-axis direction.

[0095] Furthermore, in the fifth modified example, in each of the multiple (in this case, three) grids 302 aligned in the second direction, the long prism 37 is arranged symmetrically with respect to a line (not shown) extending along the first direction. The three grids 302 are also arranged symmetrically with respect to line L10.

[0096] The other components of the fifth modification are the same as those of the fourth modification.

[0097] As explained above, in the fifth modified example, the multiple long prisms 37 are arranged symmetrically with respect to the line L10 extending along the first direction. This suppresses the asymmetry of the light emitted from the light guide plate 30 in the second direction (Y-axis direction). In other words, a symmetric light distribution characteristic in the second direction can be obtained.

[0098] [Sixth variation] Next, with reference to Figure 13, a light guide plate 30 according to a sixth modification of the present invention will be described. Figure 13 is a diagram showing the structure of the light guide plate 30 according to the sixth modification. In the sixth modification, unlike the embodiments described above, an example will be described in which a plurality of long prisms 37 are arranged in a staggered pattern.

[0099] As shown in Figure 13, in the sixth modified example, the multiple long prisms 37 are arranged in a staggered pattern. Note that in Figure 13, due to space limitations, only one grid 302 containing multiple long prisms 37 arranged in a staggered pattern is depicted, but the light guide plate 30 may have multiple grids 302 with long prisms 37 arranged in a staggered pattern. Also, in the sixth modified example, the long prisms 37 included in the grid 302 are arranged in a first direction (X-axis direction) and a second direction (Y-axis direction). Furthermore, the long prisms 37 are aligned in the first direction.

[0100] When the long prisms 37 are arranged in a staggered pattern, gaps (regions R3 where long prisms 37 are not formed) are created between adjacent long prisms 37 in the first direction at both ends along the second direction of the grid 302. Therefore, in the sixth modified example, a prism 137 is provided in region R3, with a length in the second direction being about half that of the long prisms 37. Specifically, the prism 137 is formed between adjacent long prisms 37 in the first direction at both ends along the second direction of the grid 302. The prism 137 has a shape that is shorter in the second direction than the long prism 37.

[0101] Furthermore, in the sixth modified example, similar to the fifth modified example, the long prism 37 is arranged symmetrically within the grid 302 with respect to the line L10 extending along the first direction.

[0102] The other components of the sixth variant are the same as those of the fifth variant.

[0103] As explained above, in the sixth modified example, the multiple long prisms 37 are arranged in a staggered pattern. This allows the irradiation surface (floor surface 92) to be irradiated more efficiently in the first and second directions.

[0104] [7th variation] Next, with reference to Figure 14, a light guide plate 30 according to a seventh modification of the present invention will be described. Figure 14 is a plan view showing the structure of multiple grids 302 of the light guide plate 30 according to the seventh modification. Note that in Figure 14, the long prism 37 is simplified and drawn with a thick line. In the seventh modification, unlike the embodiments described above, an example will be described in which multiple grids 302 are arranged on the light guide plate 30.

[0105] As shown in Figure 14, in the seventh modified example, the light guide plate 30 has multiple grids 302 arranged in a first direction (X-axis direction) and a second direction (Y-axis direction). Therefore, the light guide plate 30 has only one prism region R1 which is larger than in the above embodiments. Note that the light guide plate 30 may have two or more prism regions R1.

[0106] Multiple grids 302 are arranged in a first direction and a second direction. In the seventh modified example, there is almost no gap between adjacent grids 302 in the first direction (X-axis direction). Similarly, there is almost no gap between adjacent grids 302 in the second direction (Y-axis direction). The gap between adjacent grids 302 is, for example, less than or equal to the width W2 (see Figure 10) in the short-side direction (first direction) of the long prism 37.

[0107] In the seventh modification, the long prisms 37 in each grid 302 are arranged in a staggered pattern, similar to the sixth modification, but they may also be arranged in the same way as in the other modifications.

[0108] In the seventh modified example, the control surfaces 37a (see Figure 13) of the elongated prisms 37 included in each grid 302 have the same control angle θ1. On the other hand, for example, between adjacent grids 302, the control angles θ1 of the control surfaces 37a of the elongated prisms 37 are formed to be different from each other. In other words, the light guide plate 30 includes multiple types of grids 302. Note that the control angle θ1 of the control surfaces 37a of the elongated prisms 37 may be the same between adjacent grids 302. Also, in Figure 14, the line widths of elongated prisms 37 with the same control angle θ1 are made to be the same thickness. Therefore, within a single grid 302, the elongated prisms 37 are drawn with the same line width. For example, multiple grids 302 include multiple grids 302c, multiple grids 302d, and multiple grids 302e. The control angle θ1 of the control surfaces 37a of the elongated prisms 37 included in each grid 302 (each of grids 302c, 302d, and 302e) is the same. On the other hand, the control angle θ1 of the control surface 37a differs between grid 302c, grid 302d, and grid 302e.

[0109] The other components of the seventh modification are the same as those of the sixth modification.

[0110] As explained above, in the seventh modified example, the multiple long prisms 37 are arranged with almost no gaps in the first and second directions. In other words, the area where long prisms 37 are not formed is smaller compared to other modified examples. This makes it possible to increase the utilization efficiency of the light emitted from the light source 20.

[0111] Furthermore, as shown in the seventh modified example, the light guide plate 30 is formed using multiple types of grids 302. This makes it possible to easily form a light guide plate 30 having predetermined light distribution characteristics.

[0112] [8th variation] Next, with reference to Figures 15 and 16, a light guide plate 30 according to the eighth modification of the present invention will be described. Figure 15 is a plan view showing the structure of the grids 302 and 401 of the light guide plate 30 according to the eighth modification. Figure 16 is a plan view showing the structure of the grid 401 included in the light guide plate 30 according to the eighth modification. In the eighth modification, unlike the seventh modification, an example will be described in which the light guide plate 30 is provided with a grid 401 on which a plurality of conical prisms 402 are arranged.

[0113] As shown in Figure 15, in the eighth modified example, the light guide plate 30 is provided with one or more (in this case, multiple) grids 401 in addition to the multiple grids 302. The multiple grids 302 and the one or more grids 401 are arranged in a first direction (X-axis direction) and a second direction (Y-axis direction).

[0114] As shown in Figure 16, the grid 401, unlike the grid 302, is a region in which multiple conical prisms 402 are arranged in a first direction and a second direction. Unlike the elongated prism 37, the conical prism 402 has a circular shape when viewed from above. Compared to the elongated prism 37, the conical prism 402 has a light distribution characteristic that spreads in the direction along the first direction as well.

[0115] In the grid 401, the multiple conical prisms 402 are aligned in the first direction. Furthermore, similar to the long prism 37, the conical prisms 402 are offset in the first direction relative to adjacent conical prisms 402 in the second direction. In the eighth modified example, the conical prisms 402 are substantially conical concaves, but may also be conical convex portions. Additionally, the multiple conical prisms 402 may be arranged in a staggered pattern. Note that arranging the multiple conical prisms 402 in a staggered pattern can further increase the light extraction efficiency.

[0116] The other components of the eighth modification are the same as those of the seventh modification.

[0117] As explained above, in the eighth modified example, the light guide plate 30 is provided with a grid 401 on which a conical prism 402 is formed, in addition to the grid 302 on which the long prism 37 is formed. Since the conical prism 402 has different light distribution characteristics than the long prism 37, by providing the grid 401 on which the conical prism 402 is formed, it is possible to achieve a light distribution that cannot be achieved with the long prism 37 alone.

[0118] Furthermore, the conical prism 402 has a light distribution characteristic that spreads in the first direction compared to the long prism 37. Therefore, even if there are areas where the light spread in the first direction by the grid 302 is small, by placing the conical prism 402 adjacent to the grid 302 in the first direction, the light distribution characteristic of the conical prism 402 can suppress the occurrence of dark areas on the floor surface 92.

[0119] [9th variation] Next, with reference to Figure 17, a lighting device 10 according to the ninth modification of the present invention will be described. Figure 17 is an end view showing the structure of the lighting device 10 according to the ninth modification. In the ninth modification, an example will be described in which the shape of the opposing member 40 differs from that of the above embodiments.

[0120] As shown in Figure 17, in the ninth modification, the opposing member 40 has an opposing surface 41 that faces the light-emitting surface 32, similar to the embodiments described above. On the other hand, unlike the embodiments described above, the opposing member 40 does not have a non-opposing surface 42 that extends diagonally downward from the edge 41a of the opposing surface 41.

[0121] Furthermore, unlike the embodiments described above, the opposing surface 41 is arranged parallel to the light-emitting surface 32 of the light guide plate 30.

[0122] Furthermore, the opposing member 40 constitutes a part of the outer casing of the lighting device 10. As in the above embodiments, the housing 60 may be configured to accommodate the opposing member 40.

[0123] The other configurations and effects of the ninth modified example are the same as those of the embodiments described above.

[0124] [10th variation] Next, with reference to Figure 18, a lighting device 10 according to a 10th modification of the present invention will be described. Figure 18 is an end view showing the structure of the lighting device 10 according to the 10th modification. In the 10th modification, an example will be described in which a panel 50 is provided between the light guide plate 30 and the opposing member 40.

[0125] As shown in Figure 18, in the tenth modified example, a panel 50 is provided between the light guide plate 30 and the opposing member 40. The panel 50 directs the light emitted from the light-emitting surface 32 of the light guide plate 30 toward the opposing member 40 side (downward). The panel 50 serves purposes such as improving waterproofing around the light guide plate 30 and preventing foreign objects such as pebbles from hitting the light guide plate 30. Specifically, the panel 50 is, for example, a flat plate-shaped member and is arranged substantially parallel to the light-emitting surface 32. The panel 50 is a transparent member, but any member with light-transmitting properties is acceptable. The panel 50 is formed from, for example, acrylic resin, polycarbonate resin, or glass.

[0126] In the tenth modified example, a reflector 55 is provided on the main surface 31 of the light guide plate 30, facing the main surface 31. The reflector 55 has the function of reflecting the light that is incident on the light incident surface 33 and emitted from the main surface 31 back to the light guide plate 30. The surface of the reflector 55 is formed of a material with high light reflectivity. For example, the reflector 55 may be entirely made of a material with high reflectivity (such as aluminum), or it may be formed by painting or coating a material with high reflectivity onto the surface of a base material made of resin or metal.

[0127] The other configurations and effects of the 10th modified example are the same as those of the embodiments described above.

[0128] In the tenth modified example, an example was shown in which both the panel 50 and the reflector 55 are provided, but the present invention is not limited thereto. For example, only one of the panel 50 or the reflector 55 may be provided.

[0129] [11th variation] Next, with reference to Figure 19, a lighting device 10 according to the 11th modification of the present invention will be described. Figure 19 is an end view showing the structure of the lighting device 10 according to the 11th modification. In the 11th modification, an example will be described in which the opposing member 40 is a planar member that extends in the Y-axis direction and the Z-axis direction.

[0130] As shown in Figure 19, in the 11th modification, the opposing member 40 is a planar member extending in the Y-axis direction and the Z-axis direction. In the 11th modification, the opposing surface 41 of the opposing member 40 is formed by, for example, a surface 41b extending in the Y-axis direction and the Z-axis direction, and a surface 41c extending in the X-axis direction and the Y-axis direction. The edge 41a is the edge of the surface 41c in the direction opposite to the first direction.

[0131] The other configurations and effects of the 11th modification are the same as those of the embodiments described above.

[0132] [12th variation] Next, a lighting device 10 according to a 12th modification of the present invention will be described with reference to Figures 20 and 21. Figures 20 and 21 show the structure of the opposing member 40 of the lighting device 10 according to the 12th modification. In the 12th modification, an example will be described in which the opposing member 40 has a different shape from the above embodiment.

[0133] In the 12th modification, as shown in Figure 20 or Figure 21, the opposing member 40 has a structure in which multiple (in this case, two) members are joined together. Specifically, in the example shown in Figure 20, the edge 41a of the opposing surface 41 of the opposing member 40 is located in the opposite direction to the first direction (to the left in Figure 20) compared to the non-opposing surface 42. Also, in the example shown in Figure 21, the opposing surface 41 includes a surface 41d that is substantially parallel to the light-emitting surface 32 and a surface 41e that is inclined with respect to surface 41d. The edge 41a is the edge of surface 41e that is in the opposite direction to the first direction. The edge 41a is located closer to the light guide plate 30 than the rest of the opposing surface 41.

[0134] The other configurations and effects of the 12th modified example are the same as those of the embodiments described above.

[0135] [13th variation] Next, with reference to Figure 22, a lighting device 10 according to the 13th modification of the present invention will be described. Figure 22 is a diagram showing the structure of the light source 20 of the lighting device 10 according to the 13th modification. In the 13th modification, an example will be described in which the light-emitting element 22 of the light source 20 is a COB (chip-on-board) type LED element.

[0136] In the 13th modified example, as shown in Figure 22, the light source 20 includes a substrate 21, a plurality of light-emitting elements 22 consisting of LED chips mounted on the substrate 21, and a fluorescent member 23 covering the plurality of light-emitting elements 22. The fluorescent member 23 is formed of, for example, a transparent resin containing phosphor particles. The fluorescent member 23 is formed by applying and drying the resin containing phosphor particles in a line. As a result, the light source 20 emits light in a line. In the 13th modified example, the light-emitting elements 22 of the light source 20 are COB type LED elements.

[0137] The other configurations and effects of the 13th modified example are the same as those of the embodiments described above.

[0138] [14th variation] Next, with reference to Figure 23, a lighting device 10 according to the 14th modification of the present invention will be described. Figure 23 is an end view showing the structure of the lighting device 10 according to the 14th modification. In the 14th modification, an example in which the housing 60 also serves as the opposing member will be described.

[0139] In the 14th modification, as shown in Figure 23, the housing 60 also serves as the opposing member. In other words, the lighting device 10 includes a housing 60 having an opposing surface 61 that faces the light-emitting surface 32 of the light guide plate 30. In the 14th modification, there is no opposing member 40 separate from the housing 60.

[0140] Specifically, the bottom of the housing 60 is provided with an opposing surface 61 that faces the light-emitting surface 32 of the light guide plate 30. The edge 61a of the opposing surface 61 in the direction opposite to the first direction is a straight line extending along the second direction (Y-axis direction). Furthermore, a light-passing space S is formed between the end of the light guide plate 30 in the direction opposite to the first direction and the opposing surface 61 of the housing 60, through which the light emitted from the light-emitting surface 32 passes.

[0141] Furthermore, the bottom of the housing 60 has a non-facing surface 62 that does not face the light-emitting surface 32 of the light guide plate 30. The non-facing surface 62 extends vertically downward from, for example, the edge 61a of the facing surface 62 and is exposed to the outside of the lighting device 10.

[0142] The other configurations and effects of the 14th modified example are the same as those of the embodiments described above.

[0143] [Effects, etc.] The following describes examples of inventions that can be obtained from the disclosures in this specification, and explains the effects and other benefits that can be obtained from these examples.

[0144] Invention 1 comprises a main surface 31, a light-emitting surface 32 facing the main surface 31 and emitting light, and a light-incident surface 33 which is a side end surface in a first direction along the main surface 31 and the light-emitting surface 32 and into which light emitted from the light source 20 is incident. The main surface 31 is provided with a plurality of elongated prisms 37 which intersect the first direction (X-axis direction) and whose longitudinal direction is the second direction (Y-axis direction) along the main surface 31. The elongated prisms 37 have control surfaces 37a which reflect light traveling from the light-incident surface 33 in the direction opposite to the first direction to the light-emitting surface 32, and which extend along the second direction. When the region where a long prism 37 exists on the first virtual straight line L1, and the region where multiple long prisms 37 exist on at least one second virtual straight line L2 extending along the first direction is defined as the prism region R1, the light guide plate 30 is such that in the region R2 within the prism region R1, from the control surface 37a1 of the long prism 371 located at the end in the first direction to the control surface 37a2 of the long prism 372 located at the end in the direction opposite to the first direction, a control surface 37a exists on any of the first virtual straight lines L1.

[0145] With such a light guide plate 30, it is possible to reduce brightness unevenness on the illuminated surface (floor surface 92).

[0146] Invention 2 is the light guide plate 30 according to Invention 1, wherein a plurality of long prisms 37 are aligned in a first direction within the prism region R1.

[0147] With this type of light guide plate 30, for example, compared to the case where multiple long prisms 37 are not aligned in the first direction, as in the light guide plate 30 shown in Figure 3, many long prisms 37 can be arranged within the prism region R1. Therefore, light emitted from the light source 20 can be efficiently extracted from the light guide plate 30 in a predetermined direction.

[0148] Invention 3 is a light guide plate 30 according to Invention 1 or 2, wherein the prism region R1 is provided with a plurality of grids 302, which are regions in which a plurality of elongated prisms 37 are arranged in a first direction and a second direction, and the plurality of grids 302 include at least two grids 302 in which elongated prisms 37 are arranged in the same arrangement as each other.

[0149] With such a light guide plate 30, for example, if the arrangement of the long prisms 37 in one grid 302 is determined, the arrangement of the long prisms 37 in at least one other grid 302 is also determined. Therefore, the time required to design or modify the light guide plate 30 can be reduced.

[0150] Invention 4 is a light guide plate 30 according to Invention 3, wherein at least two grids 302 are arranged side by side in a second direction (Y-axis direction), and the centers O1 of at least two grids 302 are located at different positions in a first direction (X-axis direction).

[0151] With such a light guide plate 30, for example, the long prism 37 of one grid 302 and the long prism 37 of the other grid 302 are offset in the first direction (X-axis direction). As a result, the portions R10 and R20 caused by the long prism 37 of one grid 302 and the portions R10 and R20 caused by the long prism 37 of the other grid 302 are offset in the first direction. Consequently, streaky brightness unevenness extending in the second direction is less likely to occur on the floor surface 92.

[0152] Invention 5 is a light guide plate 30 according to Invention 4, wherein the centers O1 of at least two grids 302 are offset in the first direction by a distance W1 smaller than the pitch P1 of the elongated prism 37 in the first direction.

[0153] With such a light guide plate 30, the portions R10 and R20 caused by the long prism 37 of one grid 302 and the portions R10 and R20 caused by the long prism 37 of the other grid 302 can be easily shifted in the first direction.

[0154] Invention 6 is a light guide plate 30 as described in Invention 5, wherein, within a prism region R1, a plurality of long prisms 37 are arranged at a constant pitch d [mm] in a first direction (X-axis direction), and a plurality of grids 302 are arranged in a second direction (Y-axis direction), and when n different distances are provided from the light incident surface 33 to the center O1 of the grids 302, the centers O1 of the grids 302 are offset by d / n [mm].

[0155] With such a light guide plate 30, for example, the long prism 37 of grid 3021, the long prism 37 of grid 3022, and the long prism 37 of grid 3023 are arranged offset in the first direction. Therefore, portions R10 and R20 caused by the long prisms 37 of grids 3021, 3022, and 3023 can be easily shifted in the first direction. As a result, streaky brightness unevenness extending in the second direction is further reduced on the floor surface 92.

[0156] Invention 7 is a light guide plate 30 according to any one of Inventions 1 to 6, wherein a plurality of elongated prisms 37 are arranged symmetrically with respect to a line L10 extending along a first direction.

[0157] With such a light guide plate 30, it is possible to suppress the asymmetry of the light emitted from the light guide plate 30 in the second direction (Y-axis direction). In other words, it is possible to obtain a light distribution characteristic that is symmetrical in the second direction.

[0158] Invention 8 is a light guide plate 30 according to any one of Inventions 1 to 7, wherein a plurality of long prisms 37 are arranged in a staggered pattern.

[0159] With such a light guide plate 30, for example, it is easy to suppress the formation of gaps between the long prisms 37 when viewed from the first direction (X-axis direction).

[0160] Invention 9 is a lighting device 10 comprising a light guide plate 30 as described in any of Inventions 1 to 8, a light source 20 facing the light incident surface 33 of the light guide plate 30, and a facing member 40 having a facing surface 41 facing the light emission surface 32 of the light guide plate 30, wherein the edge 41a of the facing surface 41 in the direction opposite to the first direction is a straight line extending along the second direction, and a light passage space S is formed between the end of the light guide plate 30 in the direction opposite to the first direction and the facing member 40 through which light emitted from the light emission surface 32 passes.

[0161] With such a lighting device 10, it is possible to reduce brightness unevenness on the illuminated surface (floor surface 92).

[0162] Furthermore, since the edge 41a of the opposing surface 41 in the direction opposite to the first direction is a straight line extending along the second direction, unlike, for example, when the edge 41a is wavy and extends in the second direction, it is possible to suppress the appearance of the lighting device 10 when viewed from the outside (opposite side of the first direction).

[0163] Invention 10 is the illumination device 10 described in Invention 9, wherein the opposing surface 41 is inclined with respect to the light-emitting surface 32 such that the distance between the opposing surface 41 and the light-emitting surface 32 increases in the direction opposite to the first direction.

[0164] With this type of lighting device 10, it is possible to prevent foreign matter such as dust and water droplets from entering the lighting device 10.

[0165] (Other embodiments) Although embodiments and variations have been described above, the present invention is not limited to the embodiments and variations described above.

[0166] For example, in the embodiments described above, an example was given in which the light guide plate 30 is used in a lighting device that illuminates a floor surface 92, a ceiling surface, or a wall surface 91, but the present invention is not limited to this. The light guide plate 30 may also be used in a lighting device that illuminates something other than a floor surface 92, a ceiling surface, or a wall surface 91.

[0167] Furthermore, although an LED-based light-emitting module was used as the light source in the above embodiments, a light-emitting module including solid-state light-emitting elements other than LEDs, such as organic EL (Electro-Luminescence) elements or inorganic EL elements, may also be used as the light source.

[0168] Furthermore, although the above embodiments describe an example in which the light guide plate 30 is rectangular in plan view, the present invention is not limited to this. The light guide plate 30 may have a shape other than rectangular in plan view.

[0169] Furthermore, although the above embodiments describe an example in which the opposing member 40 has the function of blocking light, the present invention is not limited to this. The opposing member 40 may, for example, have the function of reflecting light. In this case, for example, the opposing member 40 may be formed by coating the surface of a substrate made of resin or metal with a highly reflective white resin, or it may be formed of a highly reflective metal (aluminum, etc.). Also, the opposing member 40 does not need to be formed of a single member, but may be composed of multiple members.

[0170] Furthermore, although the above embodiments describe an example in which the length and width of the multiple elongated prisms 37 are the same, the present invention is not limited to this. For example, the multiple elongated prisms 37 may have different lengths and / or widths.

[0171] Furthermore, the present invention also includes forms obtained by applying various modifications to each embodiment, etc., that a person skilled in the art could conceive, or forms realized by arbitrarily combining the components and functions of each embodiment, etc., without departing from the spirit of the present invention. [Explanation of Symbols]

[0172] 10 Lighting devices 20 light source 30 Light guide plate 31 Main surface 32 Light exit surface 33 Light incidence surface 37, 371, 372 Long prism 37a, 37a1, 37a2 control surfaces 40, 60 Opposing members 41, 61 Opposing surfaces 41a, 61a edge 302 grid d pitch L1 First virtual line L2 Second virtual line L10 line O1 center P1 Pitch R1 Prism Region R2 domain S light passes through space W1 Distance

Claims

1. Main surface and, A light-emitting surface facing the main surface and emitting light, The side end surface in the first direction along the main surface and the light emission surface, and the light incident surface to which light emitted from the light source is incident, Equipped with, The main surface is provided with a plurality of elongated prisms that intersect the first direction and whose longitudinal direction is the second direction along the main surface. The long prism has a control surface that reflects light traveling from the light incident surface in a direction opposite to the first direction to the light output surface, When the region in which the long prism exists on any first virtual straight line extending along the second direction, and in which a plurality of the long prisms exist on at least one second virtual straight line extending along the first direction, is defined as the prism region, Within the prism region, in the region between the control surface of the elongated prism located at the end in the first direction and the control surface of the elongated prism located at the end in the direction opposite to the first direction, the control surface exists on any of the first virtual lines. light guide plate.

2. The light guide plate according to claim 1, wherein the plurality of elongated prisms are aligned in the first direction within the prism region.

3. The prism region is provided with multiple grids, each grid in which multiple elongated prisms are arranged in a first direction and a second direction. The light guide plate according to claim 1, wherein the plurality of grids include at least two grids in which the elongated prisms are arranged in the same arrangement as each other.

4. At least two of the grids are arranged side by side in the second direction, The light guide plate according to claim 3, wherein the centers of at least two of the grids are located at different positions in the first direction.

5. The light guide plate according to claim 4, wherein the centers of at least two of the grids are offset in the first direction by a distance smaller than the pitch of the elongated prism in the first direction.

6. Within the prism region, the multiple elongated prisms are arranged in the first direction at a constant pitch d [mm]. In a plurality of grids arranged in the second direction, if n different distances are provided from the light incident surface to the center of the grid, the centers of the grids are offset by d / n [mm], as described in claim 5.

7. The light guide plate according to any one of claims 1 to 6, wherein the plurality of elongated prisms are arranged symmetrically with respect to a line extending along the first direction.

8. The light guide plate according to any one of claims 1 to 6, wherein the multiple long prisms are arranged in a staggered pattern.

9. A light guide plate according to any one of claims 1 to 6, The light source facing the light incident surface of the light guide plate, An opposing member having an opposing surface facing the light-emitting surface of the light guide plate, Equipped with, The edge of the opposing surface in the direction opposite to the first direction is a straight line extending along the second direction. Between the end of the light guide plate in the opposite direction and the opposing member, a light-passing space is formed through which light emitted from the light-emitting surface passes. Lighting device.

10. The lighting device according to claim 9, wherein the opposing surface is inclined with respect to the light-emitting surface such that the distance between the opposing surface and the light-emitting surface increases in the opposite direction.

Images