lighting equipment

Abstract

The present invention relates to a lighting device, which includes multiple light guide plates and multiple laser light source elements. The multiple light guide plates have multiple light guide plate pairs, and the multiple light guide plate pairs respectively have a first light guide plate and a second light guide plate arranged above the first light guide plate and overlapping with the first light guide plate. The multiple light guide plate pairs are connected in a manner such that their respective long sides are opposite to each other. The multiple laser light source elements include: a plurality of first light source elements arranged opposite to a first side surface of a short side of the first light guide plate of the light guide plate pair; and a plurality of second light source elements arranged opposite to a second side surface of the second light guide plate of the light guide plate pair on the opposite side of the first side surface.

Description

Technical Field

[0001] This application claims priority from Japanese patent application No. 2021-113652, filed on July 8, 2021, the entire contents of which are incorporated herein by reference.

[0002] Embodiments of the present invention relate to a lighting device. Background Art

[0003] Display devices such as liquid crystal displays (LCDs) consist of a display panel with 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 that illuminates the light from the light source element. Some illumination devices have been developed that include a laser light source as a light source element. Summary of the Invention

[0004] The present embodiment aims to provide a large-scale lighting device.

[0005] An illumination device according to one embodiment includes a plurality of light guide plates and a plurality of laser light source elements.

[0006] The plurality of light guide plates include a plurality of light guide plate pairs.

[0007] Each of the plurality of light guide plate pairs includes a first light guide plate and a second light guide plate disposed above the first light guide plate and overlapping the first light guide plate.

[0008] The plurality of light guide plate pairs are connected in such a manner that their respective long sides face each other,

[0009] The multiple laser light source elements include: a plurality of first light source elements arranged opposite to a first side surface of a short side of the first light guide plate of the light guide plate pair; and a plurality of second light source elements arranged opposite to a second side surface of the second light guide plate of the light guide plate pair, which is located on the opposite side of the first side surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a perspective view showing a schematic configuration of a display device according to an embodiment.

[0011] Figure 2 It is a top view (plan view) showing a schematic structure of the lighting device.

[0012] Figure 3 It is along Figure 1 A cross-sectional view of the display device taken along line A1-A2.

[0013] Figure 4 It is a perspective view showing an example of a connecting portion of a light guide plate.

[0014] Figure 5AThis is a cross-sectional view showing another example of the connecting portion of the light guide plate.

[0015] Figure 5B This is a cross-sectional view showing another example of the connecting portion of the light guide plate.

[0016] Figure 6 This is a cross-sectional view showing another example of the connecting portion of the light guide plate. DETAILED DESCRIPTION

[0017] Hereinafter, various embodiments of the present invention will be described with reference to the accompanying drawings. In addition, each embodiment is merely an example, and for those skilled in the art, any method obtained by making appropriate changes while maintaining the main purpose of the present invention is of course also within the scope of the present invention. In addition, with respect to the drawings, in order to make the description clearer and easier to understand, the width, thickness, shape, etc. of each part may sometimes be schematically indicated compared to the actual structure, but this is merely an example and does not limit the interpretation of the present invention. In addition, in this specification and the drawings, the same elements as those already described with respect to the previous drawings are marked with the same figure numerals, and detailed descriptions may sometimes be appropriately omitted.

[0018] Hereinafter, a lighting device and a display device according to an embodiment will be described in detail with reference to the drawings.

[0019] In this embodiment, the first direction X, the second direction Y, and the third direction Z are perpendicular to each other, but may intersect at angles other than 90 degrees. The direction toward the tip of the arrow in the third direction Z is defined as upward, and the direction opposite to the direction toward the tip of the arrow in the third direction Z is defined as downward.

[0020] In the case of the description "a second component above the first component" or "a second component below the first component," the second component may be in contact with the first component or may be spaced apart from the first component. In the latter case, a third component may be provided between the first and second components. On the other hand, in the case of the description "a second component above the first component" or "a second component below the first component," the second component is in contact with the first component.

[0021] Furthermore, observation of the lighting device from an observation position on the front side of the arrow in the third direction Z is referred to as a plan view. Observation of a cross section of the lighting device in the X-Z plane defined by the first direction X and the third direction Z, and in the Y-Z plane defined by the second direction Y and the third direction Z, is referred to as a cross-sectional view.

[0022] Example

[0023] Figure 1This is a perspective diagram schematically illustrating the structure of a display device according to an embodiment. The display device DSP includes a display panel PNL; an illumination device ILD serving as a backlight; a driver IC chip ICP that drives the display panel PNL; and a flexible circuit board FPC1 that transmits control signals 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.

[0024] The display panel PNL includes a substrate SUB1 (array substrate) and a substrate SUB2 (opposing substrate) opposing the substrate SUB1. The display panel PNL has a display area DA for displaying images. For example, the display panel PNL includes a plurality of pixels PX arranged in a matrix within the display area DA. The substrates SUB1 and SUB2 of the display panel PNL are bonded together by a sealant, though not shown here. A liquid crystal layer is enclosed in the area between the substrates SUB1 and SUB2, surrounded by the sealant.

[0025] The lighting device ILD includes a plurality of light source elements and a light guide plate LG opposite to the substrate SUB1. The light guide plate LG includes a plurality of light guide plates, which function as a single light guide plate as a whole. In this embodiment, the light guide plate LG includes three groups of light guide plate pairs, and each group (each) of light guide plate pairs is configured with one (one) light guide plate on the top and bottom, that is, two light guide plates are made into a pair. 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 thereto, and may also be two pairs or more than four pairs. The details of the optical elements will be described later.

[0026] The light guide plate LG1u is disposed above the light guide plate LG1d. In other words, the light guide plate LG1u is disposed between the light guide plate LG1d and the display panel PNL. The light guide plate LG2u is disposed above the light guide plate LG2d. In other words, the light guide plate LG2u is disposed between the light guide plate LG2d and the display panel PNL. The light guide plate LG3u is disposed above the light guide plate LG3d. In other words, the light guide plate LG3u is disposed between the light guide plate LG3d and the display panel PNL.

[0027] The light guide plates LG1u and LG1d overlap in a plan view, the light guide plates LG2u and LG2d overlap in a plan view, and the light guide plates LG3u and LG3d overlap in a plan view.

[0028] exist Figure 1 In FIG. 1 , the light guide plates LG1u and LG1d are referred to as the light guide plate LG1, the light guide plates LG2u and LG2d are referred to as the light guide plate LG2, and the light guide plates LG3u and LG3d are referred to as the light guide plate LG3. As described above, the light guide plates LG1, LG2, and LG3 also form a light guide plate pair.

[0029] Figure 2 This is a plan view schematically showing the configuration of the lighting device. The light guide plates LG1, LG2, and LG3 are arranged so that their long sides face each other. The short sides of the light guide plates LG1, LG2, and LG3 collectively constitute the long sides of the light guide plates LG.

[0030] like Figure 2 As shown, 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 a plan view.

[0031] 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.

[0032] The light guide plate LG1u includes side surfaces L1us1 and L1us2 extending in the first direction X and opposing each other. The light guide plate LG1d includes side surfaces L1ds1 and L1ds2 extending in the first direction X and opposing each other. The light source element LS11 opposes the side surface L1us1 of the light guide plate LG1u, and the light source element LS12 opposes the side surface L1ds2 of the light guide plate LG1d.

[0033] The light guide plate LG2u includes side surfaces L2us1 and L2us2 extending in the first direction X and opposing each other. The light guide plate LG2d includes side surfaces L2ds1 and L2ds2 extending in the first direction X and opposing each other. The light source element LS21 opposes the side surface L2us1 of the light guide plate LG2u, and the light source element LS22 opposes the side surface L2ds2 of the light guide plate LG2d.

[0034] The light guide plate LG3u includes side surfaces L3us1 and L3us2 extending in the first direction X and opposing each other. The light guide plate LG3d includes side surfaces L3ds1 and L3ds2 extending in the first direction X and opposing each other. The light source element LS31 opposes the side surface L3us1 of the light guide plate LG3u, and the light source element LS32 opposes the side surface L3ds2 of the light guide plate LG3d.

[0035] Side surfaces L1us1, L1ds2, L2us1, L2ds2, L3us1, and L3ds2 are the short-side surfaces of the light guide plates LG1u, LG1d, LG2u, LG2d, LG3u, and LG3d, respectively. In other words, the light source elements are arranged so as to face the short-side surfaces of the light guide plates.

[0036] The side surface L1us4 of the light guide plate LG1u and the side surface L1ds4 of the light guide plate LG1d are in contact with the side surface L2us3 of the light guide plate LG2u and the side surface L2ds3 of the light guide plate LG2d.

[0037] The side surface L2us4 of the light guide plate LG2u and the side surface L2ds4 of the light guide plate LG2d are in contact with the side surface L3us3 of the light guide plate LG3u and the side surface L3ds3 of the light guide plate LG3d.

[0038] These side surfaces are mirror surfaces, and the side surfaces provided in contact with each other are connected to each other in a state of close surface contact.

[0039] In this embodiment, the closely connected side surfaces described above are also referred to as connecting surfaces. Side surfaces L1us4 and L2us3 are the connecting surfaces between light guide plates LG1u and LG2u. Side surfaces L1ds4 and L2ds3 are the connecting surfaces between light guide plates LG1d and LG2d. Side surfaces L1us4, L2us3, L1ds4, and L2ds3 can also be considered the connecting surfaces between light guide plates LG1 and LG2. The connecting surface between light guide plates LG2 and LG3 is the same as that between light guide plates LG1 and LG2.

[0040] Side surfaces L1us4, L1ds4, L2us3, L2ds3, L2us4, L2ds4, L3us3, and L3ds3 are the side surfaces along the long sides of the light guide plates LG1u, LG1d, LG2u, LG2d, LG2u, LG2d, LG3u, and LG3d, respectively. That is, the light guide plates are connected to each other at the side surfaces along the long sides.

[0041] 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.

[0042] In a large lighting device such as a 30-inch backlight, a large molding machine with a clamping force of, for example, 800 tons or more is required in the injection molding process of the light guide plate.

[0043] On the other hand, the clamping force during the injection molding process for, for example, a 17-inch backlight's light guide plate can be reduced. However, a molding machine with a low clamping force cannot produce large light guide plates. This makes it difficult to manufacture large lighting and display devices.

[0044] In this embodiment, by arranging multiple light guide plates side by side in a backlight having a size of 18 inches or larger, it is possible to produce a larger light guide plate overall without using a large molding machine. This enables a large lighting device. Furthermore, a large display device including such a large lighting device can be obtained.

[0045] Figure 3 It is along Figure 1 A cross-sectional view of the display device taken along line A1-A2. Figure 3, only the light guide plate LG1 (LG1u and LG1d) is described, but the same applies to the other light guide plates LG2 (LG2u and LG2d, and LG3u and LG3d).

[0046] The illumination device ILD of the display device DSP includes a reflective sheet RFS, a light guide plate LG1d, a light guide plate LG1u, and a prism sheet PRS, which are sequentially arranged along the third direction Z.

[0047] Light guide plate LG1d has side surfaces L1ds1 and L1ds2, and principal surfaces L1da and L1db. As described above, light source element LS12 is disposed opposite side surface L1ds2 and not on side surface L1ds1. Principal surface L1da faces principal surface L1ub of light guide plate LG1u. Principal surface L1db faces reflective sheet RFS.

[0048] The light guide plate LG1u has side surfaces L1us1 and L1us2, and principal surfaces L1ua and L1ub. Principal surface L1ub is located opposite principal surface L1da. As described above, the light source element LS11 is located opposite side surface L1us1 and not on side surface L1us2. Principal surface L1ua faces principal surface PRb of the prism sheet PRS. Principal surface L1ub faces principal surface L1da of the light guide plate LG1d.

[0049] Let AR1d1 be the area of ​​the light guide plate LG1d that is away from the side surface L1ds2 and closer to the side surface L1ds1 (i.e., the area farther from the light source element LS12). This area AR1d1 includes the central portion L1dc of the light guide plate LG1d. Let AR1d2 be the area of ​​the light guide plate LG1d that is not AR1d1 (i.e., the area closer to the light source element LS12). This area AR1d2 does not include the central portion L1dc of the light guide plate LG1d.

[0050] Multiple protrusions TV1db are provided on the principal surface L1db of area AR1d1. These protrusions TV1db extend parallel to the first direction X and are arranged parallel to the second direction Y. Each of the multiple protrusions TV1db has a triangular prism shape, with a 130-degree vertex angle in the cross-section of the Y-Z plane. Light LT12 emitted from light source element LS12 is reflected at a reflection angle of 15 degrees by the protrusions with a 130-degree vertex angle and directed toward the front side (front surface). No protrusions TV1db are provided in area AR1d2.

[0051] Let AR1u2 be the area of ​​the light guide plate LG1u that is away from the side surface L1us1 and closer to the side surface L1us2 (i.e., the area farther from the light source element LS11). This area AR1u2 includes the central portion L1uc of the light guide plate LG1u. Let AR1u1 be the area of ​​the light guide plate LG1u that is not AR1u2 (i.e., the area closer to the light source element LS11). This area AR1u1 does not include the central portion L1uc of the light guide plate LG1u.

[0052] Area AR1u2 is provided with multiple protrusions TV1ub. These protrusions TV1ub extend parallel to the first direction X and are aligned parallel to the second direction Y. Each protrusion TV1ub has a triangular prism shape, with a 130-degree apex angle in the Y-Z plane. Light LT11 emitted from light source element LS11 is reflected at a 15-degree reflection angle by these 130-degree apex angles and directed forward. Area AR1u1 does not have any protrusions TV1ub.

[0053] The prism sheet PRS has principal surfaces PRa and PRb. The principal surface PRa faces the display panel PNL. The principal surface PRb faces the principal surface L1ua of the light guide plate LG1u. The prism sheet PRS also has a plurality of protrusions, although these are not shown.

[0054] Laser light source elements such as semiconductor lasers that emit polarized laser light can be used as the light source elements LS11 and LS12. Laser light travels straight without spreading.

[0055] Each of the light source elements LS11, LS12, LS21, LS22, LS31, and LS32 may include multiple light-emitting elements that emit light of different colors. For example, if a light source element includes three light-emitting elements that emit red, green, and blue light, respectively, a mixed color of these colors (e.g., white) can be obtained.

[0056] Light LT12 (solid line) emitted from light source element LS12 enters from side surface L1ds2 and propagates through light guide plate LG1d while being reflected in a direction opposite to the second direction Y. When light LT12 reaches area AR1d1, its reflection angle changes due to convex portion TV1db, and it is emitted toward light guide plate LG1u.

[0057] The light LT12 incident on the light guide plate LG1u passes through the region AR1u1 where the convex portion TV1ub is not provided, and is emitted toward the prism sheet PRS.

[0058] The light LT12 incident on the prism sheet PRS is reflected at a further changed angle by the convex portion of the prism sheet PRS and emitted in a direction parallel to the third direction Z, ie, a direction perpendicular to the main surface PRa of the prism sheet PRS. The emitted light LT12 is incident on the display panel PNL.

[0059] Light LT11 (dashed line) emitted from light source element LS11 enters from side surface L1us1 and propagates while being reflected in light guide plate LG1u along the second direction Y. When light LT11 reaches area AR1u2, the reflection angle is changed by convex portion TV1ub and light is emitted toward prism sheet PRS.

[0060] The light LT11 incident on the prism sheet PRS is reflected at a further changed angle by the convex portion of the prism sheet PRS and emitted in a direction parallel to the third direction Z, ie, a direction perpendicular to the main surface PRa of the prism sheet PRS. The emitted light LT11 is incident on the display panel PNL.

[0061] Light LT11 and LT12 are linearly polarized (i.e., linearly polarized light). Therefore, the display panel PNL, which is a liquid crystal display panel, only needs to be provided with a single polarizing plate (also called a "polarizer"). This allows the display panel PNL to display brighter than when two polarizing plates are provided.

[0062] In a plan view, the area AR1u2 overlaps with the area AR1d1. In this overlapping area, the central portion L1uc of the light guide plate LG1u overlaps with the central portion L1dc of the light guide plate LG1d. The area AR1u1 and the area AR1d2 do not overlap in a plan view.

[0063] return Figure 2 , the connection parts between the light guide plates are explained.

[0064] 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 a higher linearity when used as light source elements. Therefore, at the connecting portion between adjacent light guide plates, such as the connecting portion between light guide plates LG1 and LG2 (more specifically, at side surfaces L1us4 and L2us3, and side surfaces L1ds4 and L2ds3), there is an advantage in that reflection from these side surfaces is minimal, making the connecting portion less noticeable.

[0065] Figure 4 This is a perspective view showing an example of the connecting portion of the light guide plates. Side surfaces L1us4 and L2us3 are in close contact, forming the connecting surface between the light guide plates LG1u and LG2u, while side surfaces L1ds4 and L2ds3 are in close contact, forming the connecting surface between the light guide plates LG1d and LG2d. As described above, these connecting surfaces are mirror surfaces.

[0066] The side surfaces L1us4 and L2us3, and the side surfaces L1ds4 and L2ds3 overlap in a plan view, and these side surfaces also constitute the connection surfaces of the light guide plates LG1 and LG2, which form a light guide plate pair.

[0067] According to this embodiment, a large-scale illumination device with little reflection from the side surface of the light guide plate and an inconspicuous connection portion can be obtained. In addition, a large-scale display device having such an illumination device can be provided.

[0068] Figure 5A and Figure 5B This is a cross-sectional view showing another example of the connecting portion of the light guide plate. Figure 5A and Figure 5B In the example shown, Figure 4 Compared to the example shown, the connection portion is different in that it is not in close contact.

[0069] Figure 5A This is a cross-sectional view of the vicinity of the connection portion of the light guide plates LG1 and LG2. The light guide plate LG1u has end portions E1ua and E1ub on its main surfaces L1ua and L1ub, respectively. The light guide plate LG2u has end portions E2ua and E2ub on its main surfaces L2ua and L2ub, respectively.

[0070] Ends E1ua and E2ua are adjacent to each other, while ends E1ub and E2ub are arranged facing each other nearby but not in contact.

[0071] Alternatively, the ends E1ua and E2ua may be arranged adjacent to each other but not in contact with each other, and the distance between the ends E1ua and E2ua may be longer than the distance between the ends E1ub and E2ub.

[0072] The cross-sectional shape of the light guide plates LG1u and LG2u in the XZ plane near the connection portion is a wedge shape. The side surface L1us4 of the light guide plate LG1u is not in close contact with the side surface L2us3 of the light guide plate LG2u.

[0073] Like the light guide plates LG1u and LG2u, the light guide plate LG1d has end portions E1da and E1db on its principal surfaces L1da and L1db, respectively. The light guide plate LG2d has end portions E2da and E2db on its principal surfaces L2da and L2db, respectively.

[0074] Ends E1da and E2da are adjacent to each other, while ends E1db and E2db are arranged facing each other nearby but not in contact.

[0075] Alternatively, the ends E1da and E2da may be arranged adjacent to each other but not in contact with each other, and the distance between the ends E1da and E2da may be longer than the distance between the ends E1db and E2db.

[0076] The cross-sectional shape in the XZ plane near the connection portion between the light guide plates LG1d and LG2d is a wedge shape. 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.

[0077] like Figure 5A The structure of the light guide plates LG1 and LG2 is similar to Figure 4 In comparison, it has the advantage that the connection portion is less conspicuous.

[0078] Figure 5B This is a cross-sectional view near the connection portion of the light guide plates LG1 and LG2. Figure 5B In the example shown, Figure 5A Compared with the example shown, the cross-sectional shape of the connecting portion of the light guide plate pair is wedge-shaped.

[0079] exist Figure 5B , the distance between the end portions E1ua and E2ua, the distance between the end portions E1ub and E2ub, the distance between the end portions E1da and E2da, and the distance between the end portions E1db and E2db become longer in this order.

[0080] As described above, the light guide plate LG1 including the light guide plates LG1u and LG1d and the light guide plate LG2 including the light guide plates LG2u and LG2d also form a light guide plate pair. The cross-sectional shape of the connecting portion of the light guide plates LG1 and LG2 in the XZ plane is a wedge shape.

[0081] according to Figure 5B , and a lighting device with an inconspicuous connection portion can also be obtained.

[0082] Figure 6 : is a cross-sectional view showing another example of the connecting portion of the light guide plate. Figure 6 In the example shown, the connecting surface is separated by a gap between the upper and lower light guide plates. Figure 4 The examples shown are different.

[0083] exist Figure 6 In the example shown, the side surfaces L1us4 and L2us3 do not overlap with L1ds4 and L2ds3 in the third direction Z. The end portions E1ub and E2ub and the end portions E1da and E2da are located on the same XY plane but are spaced apart from each other.

[0084] like Figure 6 As shown, when the connection surface of the upper light guide plates LG1u and LG2u is spaced apart from the connection surface of the lower light guide plates LG1d and LG2d, the connection surface becomes less noticeable.

[0085] In this specification, two light guide plates are referred to as a light guide plate pair. The lower light guide plate in the pair is also referred to as a first light guide plate, and the upper light guide plate is also referred to as a second light guide plate.

[0086] The long side and short side of each light guide plate included in the light guide plate pair are also referred to as the long side and short side of the light guide plate pair.

[0087] make Figure 3 The center L1dc of the light guide plate LG1d is referred to as the first center, and the center L1uc of the light guide plate LG1u is referred to as the second center. The regions AR1d1, AR1d2, AR1u1, and AR1u2 are also referred to as the first, second, third, and fourth regions, respectively.

[0088] The convex portion TV1db and the convex portion TV1ub are also referred to as a first convex portion and a second convex portion, respectively.

[0089] Will Figure 5A and Figure 5B The main surfaces L1ua and L2ua shown are referred to as first main surfaces. The main surfaces L1ub and L2ub are referred to as second main surfaces. The main surfaces L1da and L2da are referred to as third main surfaces. The main surfaces L1db and L2db are referred to as fourth main surfaces.

[0090] Ends E1ua and E2ua are referred to as first ends, ends E1ub and E2ub are referred to as second ends, ends E1da and E2da are referred to as third ends, and ends E1db and E2db are referred to as fourth ends.

[0091] Some embodiments of the present invention have been described above, but these embodiments are provided as examples and are not intended to limit the scope of the present invention. These new embodiments can be implemented in various other ways and can be omitted, replaced, or modified without departing from the scope of the present invention. These embodiments and their variations are included within the scope and spirit of the invention and are included within the scope of the invention described in the claims (part of the summary of the invention) and their equivalents.

Claims

1. A lighting device, characterized in that: including a plurality of light guide plates and a plurality of laser light source elements, 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 disposed above the first light guide plate and overlapping the first light guide plate. The plurality of light guide plate pairs are connected in such a manner that their respective long sides face each other, The plurality of laser light source elements include: a plurality of first light source elements arranged opposite to a first side surface of a short side of the first light guide plate of the pair of light guide plates; and a plurality of second light source elements arranged opposite to a second side surface of the second light guide plate of the pair of light guide plates on a side opposite to the first side surface. The plurality of light guide plate pairs include adjacent first and second light guide plate pairs. 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. The first end of the first main surface of the second light guide plate of the first light guide plate pair contacts the first end of the first main surface of the second light guide plate of the second light guide plate pair. The second end portion of the second main surface of the second light guide plate of the first light guide plate pair is spaced apart from the second end portion of the second main surface of the second light guide plate of the second light guide plate pair.

2. The lighting device according to claim 1, wherein: The first light guide plate includes a first region including a first central portion and a second region not including the first central portion. The second light guide plate includes a third region excluding the second central portion and a fourth region including the second central portion. A plurality of first protrusions are provided in the first region, A plurality of second protrusions are provided in the fourth region, The first area is farther away from the first light source element than the second area. The fourth region is farther from the second light source element than the third region.

3. The lighting device according to claim 2, wherein: In a plan view, the second area does not overlap with the third area.

4. The lighting device according to claim 1, wherein: 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 main surface and a fourth main surface opposite to the third main surface. The third end portion of the third main surface of the first light guide plate of the first light guide plate pair contacts the third end portion of the third main surface of the first light guide plate of the second light guide plate pair. The fourth end portion of the fourth main surface of the first light guide plate of the first light guide plate pair is spaced apart from the fourth end portion of the fourth main surface of the first light guide plate of the second light guide plate pair.

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