lighting equipment

Abstract

To provide a large-sized lighting device.SOLUTION: A lighting device comprises a plurality of light guide plates and a plurality of laser light source elements, the plurality of light guide plates have a plurality of light guide plate pairs, and the plurality of light guide pairs have first light guide plates and second light guide plates which are arranged above the first light guide plates while being superimposed thereon. The plurality of light guide pairs are connected to each other while opposing each other at long sides. The plurality of laser light source elements include: a plurality of first light source elements which are arranged while opposing first side faces of the first light guide plates of the light guide plate pairs at short-side sides; and a plurality of second light source elements which are arranged while opposing second side faces at sides opposite to the first side faces of the second light guide plates of the light guide plate pairs.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] FIELD OF THE INVENTION An embodiment of the present invention relates to a lighting device. [Background technology]

[0002] A display device such as a liquid crystal display device includes a display panel having pixels and an illumination device such as a backlight that illuminates the display panel. The illumination device includes a light source element that emits light and a light guide plate onto which the light from the light source element is irradiated. Illumination devices that include a laser light source as the light source element have been developed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-181729 Summary of the Invention [Problem to be solved by the invention]

[0004] This embodiment provides a large-sized lighting device. [Means for solving the problem]

[0005] An illumination device according to an embodiment includes: A plurality of light guide plates; A plurality of laser light source elements; Equipped with the plurality of light guide plates include a plurality of light guide plate pairs; each of the plurality of light guide plate pairs includes a first light guide plate and a second light guide plate provided above the first light guide plate so as to overlap the first light guide plate; The plurality of light guide pairs are connected with their long sides facing each other, The plurality of laser light source elements include a plurality of first light source elements arranged opposite a first side surface on the short side of the first light guide plate of the light guide plate pair, and a plurality of second light source elements arranged opposite a second side surface on the opposite side to the first side surface of the second light guide plate of the light guide plate pair. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a perspective view showing a schematic configuration of a display device according to an embodiment. [Figure 2] FIG. 2 is a plan view showing a schematic configuration of the lighting device. [Figure 3] FIG. 3 is a cross-sectional view of the display device taken along line A1-A2 in FIG. [Figure 4] FIG. 4 is a perspective view showing an example of a connecting portion of a light guide plate. [Figure 5A] FIG. 5A is a cross-sectional view showing another example of a connecting portion of a light guide plate. [Figure 5B] FIG. 5B is a cross-sectional view showing another example of a connecting portion of a light guide plate. [Figure 6] FIG. 6 is a cross-sectional view showing another example of a connecting portion of a light guide plate. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, each embodiment of the present invention will be described with reference to the drawings. The disclosure is merely an example, and appropriate modifications that a person skilled in the art can easily conceive while maintaining the gist of the invention are naturally included within the scope of the present invention. Furthermore, in order to clarify the explanation, the drawings may show the width, thickness, shape, etc. of each part schematically compared to the actual embodiment, but these are merely examples and are not intended to limit the interpretation of the present invention. Furthermore, in this specification and each drawing, elements similar to those described above with reference to the previous drawings may be designated by the same reference numerals, and detailed descriptions may be omitted as appropriate. Hereinafter, an illumination device and a display device according to an embodiment will be described in detail with reference to the drawings.

[0008] In this embodiment, the first direction X, the second direction Y, and the third direction Z are perpendicular to one another, but may intersect at an angle other than 90 degrees. The direction toward the tip of the arrow of the third direction Z is defined as up or upward, and the direction opposite to the direction toward the tip of the arrow of the third direction Z is defined as down or downward.

[0009] Furthermore, when the terms "second member above the first member" and "second member below the first member" are used, the second member may be in contact with the first member or may be located apart from the first member. In the latter case, a third member may be interposed between the first and second members. On the other hand, when the terms "second member above the first member" and "second member below the first member" are used, the second member is in contact with the first member.

[0010] Furthermore, the observation position for observing the lighting device is assumed to be at the tip of the arrow in the third direction Z, and a planar view refers to a view from this observation position toward the XY plane defined by the first direction X and the second direction Y. A cross-sectional view refers to a view of a cross section of the lighting device in the XZ plane defined by the first direction X and the third direction Z, or in the YZ plane defined by the second direction Y and the third direction Z.

[0011] 1 is a perspective view showing a schematic configuration of a display device according to an embodiment. The display device DSP includes a display panel PNL, an illumination device ILD as a backlight, a driving IC chip ICP for driving the display panel PNL, and a flexible circuit board FPC1 for transmitting a control signal for the display panel PNL. For example, the flexible circuit board FPC1 is connected to a control module that controls the operation of the display panel PNL.

[0012] The display panel PNL comprises a substrate SUB1 (array substrate) and a substrate SUB2 (counter substrate) facing the substrate SUB1. The display panel PNL has a display area DA in which an image is displayed. The display panel PNL comprises, for example, a plurality of pixels PX arranged in a matrix in the display area DA. Although not shown, the substrates SUB1 and SUB2 of the display panel PNL are bonded together by a sealing material. A liquid crystal layer is sealed in the area between the substrates SUB1 and SUB2 and surrounded by the sealing material.

[0013] The illumination device ILD includes a plurality of light source elements and a light guide plate LG facing the substrate SUB1. The light guide plate LG has a plurality of light guide plates, and functions as a single light guide plate as a whole. In this embodiment, the light guide plates LG are arranged one above the other, i.e., three pairs of light guide plates, each consisting of two light guide plates. Specifically, the light guide plate LG includes six light guide plates LG1u, LG1d, LG2u, LG2d, LG3u, and LG3d. However, the number of light guide plates is not limited to this, and may be two pairs, or four or more pairs. Details of the optical elements will be described later.

[0014] The light guide plate LG1u is provided above the light guide plate LG1d. In other words, the light guide plate LG1u is provided between the light guide plate LG1d and the display panel PNL. The light guide plate LG2u is provided above the light guide plate LG2d. In other words, the light guide plate LG2u is provided between the light guide plate LG2d and the display panel PNL. The light guide plate LG3u is provided above the light guide plate LG3d. In other words, the light guide plate LG3u is provided between the light guide plate LG3d and the display panel PNL.

[0015] The light guide plates LG1u and LG1d, LG2u and LG2d, and LG3u and LG3d overlap each other in plan view. 1, light guide plates LG1u and LG1d, LG2u and LG2d, and LG3u and LG3d are also referred to as light guide plates LG1, LG2, and LG3, respectively. As described above, light guide plates LG1, LG2, and LG3 are also light guide plate pairs.

[0016] 2 is a plan view showing a schematic configuration of the lighting device. Light guide plates LG1, LG2, and LG3 are arranged with their long sides facing each other. The short sides of light guide plates LG1, LG2, and LG3 collectively form the long side of the light guide plate LG.

[0017] As shown in FIG. 2, the substrates SUB1 and SUB2 and the light guide plate LG have long sides along the first direction X and short sides along the second direction Y, and are rectangular in shape in a plan view. Each of the light guide plates LG1, LG2, and LG3 has a short side along the first direction X and a long side along the second direction Y. A plurality of light source elements are provided on the side surfaces of the short sides.

[0018] Light guide plate LG1u extends along first direction X and has side surfaces L1us1 and L1us2 facing each other. Light guide plate LG1d extends along first direction X and has side surfaces L1ds1 and L1ds2 facing each other. Light source element LS11 faces side surface L1us1 of light guide plate LG1u, and light source element LS12 faces side surface L1ds2 of light guide plate LG1d.

[0019] Light guide plate LG2u extends along the first direction X and has side surfaces L2us1 and L2us2 facing each other. Light guide plate LG2d extends along the first direction X and has side surfaces L2ds1 and L2ds2 facing each other. Light source element LS21 faces side surface L2us1 of light guide plate LG2u, and light source element LS22 faces side surface L2ds2 of light guide plate LG2d.

[0020] Light guide plate LG3u extends along the first direction X and has side surfaces L3us1 and L3us2 facing each other. Light guide plate LG3d extends along the first direction X and has side surfaces L3ds1 and L3ds2 facing each other. Light source element LS31 faces the side surface L3us1 of light guide plate LG3u, and light source element LS32 faces the side surface L3ds2 of light guide plate LG3d.

[0021] Side surface L1us1, side surface L1ds2, side surface L2us1, side surface L2ds2, side surface L3us1, and side surface L3ds2 are the side surfaces on the short sides of light guide plate LG1u, light guide plate LG1d, light guide plate LG2u, light guide plate LG2d, light guide plate LG3u, and light guide plate LG3d, respectively. In other words, it can be said that the light source elements are arranged facing the side surfaces on the short sides of the light guide plates.

[0022] The side surface L1us4 of the light guide plate LG1u and the side surface L1ds4 of the light guide plate LG1d are provided in contact with the side surface L2us3 of the light guide plate LG2u and the side surface L2ds3 of the light guide plate LG2d. The side surface L2us4 of the light guide plate LG2u and the side surface L2ds4 of the light guide plate LG2d are provided in contact with the side surface L3us3 of the light guide plate LG3u and the side surface L3ds3 of the light guide plate LG3d. These side surfaces are mirror surfaces, and the side surfaces that are in contact with each other are connected in a state where the surfaces are in close contact with each other.

[0023] In this embodiment, the side surfaces that are tightly connected as described above are also referred to as connection surfaces. Side surfaces L1us4 and L2us3 are connection surfaces between light guide plates LG1u and LG2u. Side surfaces L1ds4 and L2ds3 are connection surfaces between light guide plates LG1d and LG2d. Side surfaces L1us4, L2us3, L1ds4, and L2ds3 can also be said to be connection surfaces between light guide plates LG1 and LG2. The connection surfaces between light guide plates LG2 and LG3 are similar to those between light guide plates LG1 and LG2.

[0024] Side surface L1us4, side surface L1ds4, side surface L2us3, side surface L2ds3, side surface L2us4, side surface L2ds4, side surface L3us3, and side surface L3ds3 are the side surfaces on the long sides of light guide plate LG1u, light guide plate LG1d, light guide plate LG2u, light guide plate LG2d, light guide plate LG2u, light guide plate LG2d, light guide plate LG3u, and light guide plate LG3d, respectively. In other words, the light guide plates are connected at their respective side surfaces on the long sides. No light source is arranged on the side surfaces L1us3, L1ds3, L3us4, and L3ds4 located on the short sides of the light guide plate LG.

[0025] For a large lighting device, such as a 30-inch backlight, the process of injection molding the light guide plate requires a large molding machine with a clamping force of 800 tons or more. On the other hand, for example, a light guide plate for a 17-inch backlight can be injection molded with a small clamping force. However, a molding machine with a small clamping force cannot manufacture large light guide plates. This makes it difficult to manufacture large lighting devices and display devices. In this embodiment, by arranging multiple light guide plates side by side in a backlight having a size of 18 inches or more, it is possible to obtain a large overall light guide plate without using a large molding machine. This makes it possible to obtain a large illumination device. Furthermore, it is possible to obtain a large display device equipped with such a large illumination device.

[0026] Fig. 3 is a cross-sectional view of the display device taken along line A1-A2 in Fig. 1. Although Fig. 3 only shows light guide plate LG1 (LG1u and LG1d), the same applies to the other light guide plates LG2 (LG2u and LG2d, and LG3u and LG3d). The illumination device ILD of the display device DSP includes a reflection sheet RFS, a light guide plate LG1d, a light guide plate LG1u, and a prism sheet PRS, which are arranged in this order along the third direction Z.

[0027] The light guide plate LG1d has side surfaces L1ds1 and L1ds2 and main surfaces L1da and L1db. As described above, the light source element LS12 is provided facing the side surface L1ds2 and is not provided on the side surface L1ds1. The main surface L1da faces the main surface L1ub of the light guide plate LG1u. The main surface L1db faces the reflection sheet RFS. The light guide plate LG1u has side surfaces L1us1 and L1us2 and main surfaces L1ua and L1ub. The main surface L1ub is provided on the opposite side of the main surface L1da. As described above, the light source element LS11 is provided facing the side surface L1us1 and is not provided on the side surface L1us2. The main surface L1ua faces the main surface PRb of the prism sheet PRS. The main surface L1ub faces the main surface L1da of the light guide plate LG1d.

[0028] Of the regions of light guide plate LG1d, the region far from side surface L1ds2 and close to side surface L1ds1, i.e., the region far from light source element LS12, is designated AR1d1. Region AR1d1 includes central portion L1dc of light guide plate LG1d. Of the regions of light guide plate LG1d, the region other than region AR1d1, i.e., the region closer to light source element LS12, is designated AR1d2. Region AR1d2 does not include central portion L1dc of light guide plate LG1d.

[0029] The main surface L1db of the region AR1d1 is provided with a plurality of protrusions TV1db extending in a direction parallel to the first direction X and arranged side by side in a direction parallel to the second direction Y. Each of the plurality of protrusions TV1db has a triangular prism shape, and its cross-sectional shape in the YZ plane is formed so that its apex angle is 130 degrees. Light LT12 emitted from the light source element LS12 is reflected at a reflection angle of 15 degrees by the protrusions with an apex angle of 130 degrees and is guided to the front side. The region AR1d2 does not have a convex portion TV1db.

[0030] Of the regions of light guide plate LG1u, the region far from side surface L1us1 and close to side surface L1us2, i.e., the region far from light source element LS11, is referred to as AR1u2. Region AR1u2 includes center portion L1uc of light guide plate LG1u. Of the regions of light guide plate LG1u, the region other than region AR1u2, i.e., the region close to light source element LS11, is referred to as AR1u1. Region AR1u1 does not include center portion L1uc of light guide plate LG1u.

[0031] The region AR1u2 is provided with a plurality of protrusions TV1ub that extend in a direction parallel to the first direction X and are arranged side by side in a direction parallel to the second direction Y. Each of the plurality of protrusions TV1ub has a triangular prism shape, and its cross-sectional shape in the YZ plane is formed with an apex angle of 130 degrees. Light LT11 emitted from the light source element LS11 is reflected at a reflection angle of 15 degrees by the protrusion with an apex angle of 130 degrees and is guided to the front side. The region AR1u1 does not have a protruding portion TV1ub.

[0032] The prism sheet PRS has two main surfaces PRa and PRb. The main surface PRa faces the display panel PNL. The main surface PRb faces the main surface L1ua of the light guide plate LG1u. Although not shown, the prism sheet PRS also has a plurality of protrusions.

[0033] The light source elements LS11 and LS12 may be laser light source elements such as semiconductor lasers that emit polarized laser light. The laser light travels straight without diverging. Each of the light source elements LS11, LS12, LS21, LS22, LS31, and LS32 may include a plurality of light emitting elements that emit light of different colors. For example, if one light source element includes three light emitting elements that emit red, green, and blue light, a mixed color (e.g., white) of these colors can be obtained.

[0034] Light LT12 (solid line) emitted from light source element LS12 enters from side surface L1ds2 and propagates within light guide plate LG1d while being reflected in the direction opposite to second direction Y. When light LT12 reaches area AR1d1, the angle of reflection is changed by convex portion TV1db, and the light is emitted toward light guide plate LG1u. Light LT12 incident on the light guide plate LG1u passes through an area AR1u1 where the convex portion TV1ub is not provided, and is emitted toward the prism sheet PRS.

[0035] The light LT12 incident on the prism sheet PRS has its reflection angle further changed by the convex portions of the prism sheet PRS, and is emitted in a direction parallel to the third direction Z, i.e., in a direction perpendicular to the main surface PRa of the prism sheet PRS. The emitted light LT12 is incident on the display panel PNL.

[0036] Light LT11 (dotted line) emitted from light source element LS11 enters from side surface L1us1 and propagates while being reflected within light guide plate LG1u along second direction Y. When light LT11 reaches area AR1u2, the reflection angle is changed by convex portion TV1ub, and the light LT11 is emitted toward prism sheet PRS.

[0037] The light LT11 incident on the prism sheet PRS is further reflected by the convex portions of the prism sheet PRS at a different angle, and is emitted in a direction parallel to the third direction Z, i.e., in a direction perpendicular to the main surface PRa of the prism sheet PRS. The emitted light LT11 is incident on the display panel PNL.

[0038] The light LT11 and LT12 are linearly polarized light. Therefore, the display panel PNL, which is a liquid crystal display panel, only needs to be provided with one polarizing plate. Compared to when two polarizing plates are provided, the display on the display panel PNL can be brighter.

[0039] The region AR1u2 and the region AR1d1 overlap in a planar view. The overlapping region overlaps with the center portion L1uc of the light guide plate LG1u and the center portion L1dc of the light guide plate LG1d in a planar view. The region AR1u1 and the region AR1d2 do not overlap in a planar view.

[0040] Returning to FIG. 2, the connection portions between the light guide plates will be described. As described above, the light source element of this embodiment emits laser light. Compared to light source elements such as light-emitting diodes (LEDs), laser light sources have high linearity. Therefore, at the connection portions of adjacent light guide plates, for example, the connection portions between light guide plates LG1 and LG2, more specifically, the side surfaces L1us4 and L2us3, and the side surfaces L1ds4 and L2ds3, reflection from the side surfaces is low, which is advantageous in that the connection portions are not noticeable.

[0041] 4 is a perspective view showing an example of a connection portion of a light guide plate. The side surfaces L1us4 and L2us3, and the side surfaces L1ds4 and L2ds3 are closely attached to each other and form the connection surfaces of the light guide plates LG1u and LG2u, and the connection surfaces of the light guide plates LG1d and LG2d, respectively. As described above, the connection surfaces are mirrored.

[0042] The side surfaces L1us4 and L2us3, and the side surfaces L1ds4 and L2ds3 overlap each other in plan view, and also form connecting surfaces for the light guide plates LG1 and LG2 that make up the light guide plate pair. According to this embodiment, it is possible to obtain a large-sized illumination device with less reflection from the side surfaces of the light guide plate and with inconspicuous connecting portions, and also to provide a large-sized display device having such an illumination device.

[0043] 5A and 5B are cross-sectional views showing another example of the connecting portion of the light guide plate. The examples shown in Fig. 5A and 5B differ from the example shown in Fig. 4 in that the connecting portion is not in close contact.

[0044] 5A is a cross-sectional view of the vicinity of the joint between light guide plates LG1 and LG2. Light guide plate LG1u has ends E1ua and E1ub on its main surfaces L1ua and L1ub, respectively. Light guide plate LG2u has ends E2ua and E2ub on its main surfaces L2ua and L2ub, respectively.

[0045] The ends E1ua and E2ua are adjacent to each other, while the ends E1ub and E2ub are disposed adjacent to each other but are not in contact with each other. Alternatively, the ends E1ua and E2ua may be disposed close to each other but not in contact with each other, and the distance between the ends E1ua and E2ua is greater than the distance between the ends E1ub and E2ub. The cross section of the light guide plates LG1u and LG2u in the XZ plane near the joint is wedge-shaped. The side surface L1us4 of the light guide plate LG1u and the side surface L2us3 of the light guide plate LG2u are not in close contact with each other.

[0046] Like light guide plates LG1u and LG2u, light guide plate LG1d has ends E1da and E1db on its principal surfaces L1da and L1db, respectively. Light guide plate LG2d has ends E2da and E2db on its principal surfaces L2da and L2db, respectively.

[0047] The ends E1da and E2da are adjacent to each other, while the ends E1db and E2db are disposed adjacent to each other but are not in contact with each other. Alternatively, the ends E1da and E2da may be disposed close to each other but not in contact with each other. The distance between the ends E1da and E2da is longer than the distance between the ends E1db and E2db.

[0048] The cross section of the light guide plates LG1d and LG2d in the vicinity of the joint on the XZ plane is wedge-shaped. The side surface L1ds4 of the light guide plate LG1d and the side surface L2ds3 of the light guide plate LG2d are not in close contact with each other. The configuration in which the light guide plates LG1 and LG2 are arranged as shown in FIG. 5A has the advantage that the connecting portion is less noticeable than that shown in FIG.

[0049] Fig. 5B is a cross-sectional view of the vicinity of the connection portion of the light guide plates LG1 and LG2. The example shown in Fig. 5B differs from the example shown in Fig. 5A in that the cross-sectional shape of the connection portion of the pair of light guide plates is wedge-shaped. In FIG. 5B, the distance between ends E1ua and E2ua, the distance between ends E1ub and E2ub, the distance between ends E1da and E2da, and the distance between ends E1db and E2db are long in this order. As described above, light guide plate LG1 including light guide plates LG1u and LG1d and light guide plate LG2 including light guide plates LG2u and LG2d are also light guide plate pairs. The connection portion of light guide plates LG1 and LG2 has a wedge-shaped cross section in the XZ plane. FIG. 5B also makes it possible to obtain a lighting device in which the connecting portions are not noticeable.

[0050] Fig. 6 is a cross-sectional view showing another example of the connecting portion of the light guide plate. The example shown in Fig. 6 differs from the example shown in Fig. 4 in that the connecting surfaces of the upper and lower light guide plates are separated. 6, the side surfaces L1us4 and L2us3, and L1ds4 and L2ds3 do not overlap with each other in the third direction Z. The ends E1ub and E2ub, and the ends E1da and E2da are located on the same XY plane but are spaced apart.

[0051] 6, if the connecting surfaces of the upper light guide plates LG1u and LG2u and the connecting surfaces of the lower light guide plates LG1d and LG2d are spaced apart, the connecting surfaces become even less noticeable, thereby making it possible to obtain a lighting device in which the connecting portions are even less noticeable.

[0052] In the present disclosure, of a pair of light guide plates, the lower light guide plate is also referred to as the first light guide plate, and the upper light guide plate is also referred to as the second light guide plate. The long and short sides of each light guide plate included in the light guide plate pair are also referred to as the long and short sides of the light guide plate pair. 3, the central portion L1dc of the light guide plate LG1d is referred to as the first central portion, and the central portion L1uc of the light guide plate LG1u is referred to as the second central portion. The regions AR1d1, AR1d2, AR1u1, and AR1u2 are also referred to as the first region, the second region, the third region, and the fourth region, respectively. The convex portion TV1db and the convex portion TV1ub are also referred to as a first convex portion and a second convex portion, respectively.

[0053] 5A and 5B, the principal surfaces L1ua and L2ua are referred to as first principal surfaces, the principal surfaces L1ub and L2ub are referred to as second principal surfaces, the principal surfaces L1da and L2da are referred to as third principal surfaces, and the principal surfaces L1db and L2db are referred to as fourth principal surfaces. The ends E1ua and E2ua are referred to as first ends, the ends E1ub and E2ub as second ends, the ends E1da and E2da as third ends, and the ends E1db and E2db as fourth ends.

[0054] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0055] AR1d1...area, AR1d2...area, AR1u1...area, AR1u2...area, DSP...display device, ILD...illumination device, L1da...main surface, L1db...main surface, L1dc...center part, L1ds1...side, L1ds2...side, L1ua...main surface, L1ub...main surface, L1uc...center, L1us1...side, L1us2...side, L1us4...side, L2da...main surface, L2ds2...side surface, L2ua...main surface, L2us1...side surface, LG1d...light guide plate, LG1u...light guide plate, LG2d...light guide plate, LG2u...light guide plate, LS11...light source element, LS12...light source element, LS21...light source element, LS22...light source element, LS31...light source element, LT11...light, LT12...light, PNL...display panel, TV1db...convex portion, TV1ub...convex portion.

Claims

1. A plurality of light guide plates; a plurality of laser light source elements; Equipped with the plurality of light guide plates include a plurality of light guide plate pairs; each of the plurality of light guide plate pairs includes a first light guide plate and a second light guide plate provided above the first light guide plate so as to overlap the first light guide plate; The plurality of light guide plate pairs are connected with their long sides facing each other, the plurality of laser light source elements include a plurality of first light source elements arranged to face a first side surface on a short side of the first light guide plate of the light guide plate pair, and a plurality of second light source elements arranged to face a second side surface opposite to the first side surface of the second light guide plate of the light guide plate pair, the plurality of light guide plate pairs include a first light guide plate pair and a second light guide plate pair adjacent to each other; the second light guide plate of the first light guide plate pair and the second light guide plate of the second light guide plate pair each have a first main surface and a second main surface opposite to the first main surface, a first end portion of the first main surface of the second light guide plate of the first light guide plate pair and a first end portion of the first main surface of the second light guide plate of the second light guide plate pair are in contact with each other, a second end of the second main surface of the second light guide plate of the first light guide plate pair and a second end of the second main surface of the second light guide plate of the second light guide plate pair are spaced apart.

2. The first light guide plate has a first region including a first central portion and a second region not including the first central portion. the second light guide plate has a third region that does not include the second central portion, and a fourth region that includes the second central portion; a plurality of first protrusions provided in the first region; a plurality of second convex portions provided in the fourth region; Furthermore, the first region is farther from the first light source element than the second region; The lighting device according to claim 1 , wherein the fourth region is farther from the second light source element than the third region.

3. The lighting device according to claim 2 , wherein the second region and the third region do not overlap in a plan view.

4. The lighting device according to claim 2 , wherein each of the plurality of first protrusions and each of the plurality of second protrusions has a triangular cross-sectional shape.

5. the plurality of light guide plate pairs include a first light guide plate pair and a second light guide plate pair adjacent to each other; 2. The lighting device according to claim 1, wherein a coupling surface between the first light guide plate of the first light guide plate pair and the first light guide plate of the second light guide plate pair overlaps a coupling surface between the second light guide plate of the first light guide plate pair and the second light guide plate of the second light guide plate pair in a planar view.

6. the plurality of light guide plate pairs include a first light guide plate pair and a second light guide plate pair adjacent to each other; 2. The lighting device according to claim 1, wherein a coupling surface between the first light guide plate of the first light guide plate pair and the first light guide plate of the second light guide plate pair is spaced apart from a coupling surface between the second light guide plate of the first light guide plate pair and the second light guide plate of the second light guide plate pair. The lighting device according to claim 1 .

7. the first light guide plate of the first light guide plate pair and the first light guide plate of the second light guide plate pair each have a third major surface and a fourth major surface opposite to the third major surface, a third end portion of the third main surface of the first light guide plate of the first light guide plate pair and a third end portion of the third main surface of the first light guide plate of the second light guide plate pair are in contact with each other, 2 . The lighting device according to claim 1 , wherein a fourth end of the fourth main surface of the first light guide plate of the first light guide plate pair and a fourth end of the fourth main surface of the first light guide plate of the second light guide plate pair are spaced apart.

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