Planar lighting device

Abstract

A planar lighting device (1) according to an embodiment is a straight down type planar lighting device (1) provided with a linear Fresnel lens (6a), and is provided with a plurality of light sources (4) and a reflector (5). The plurality of light sources (4) are arranged on the substrate (3) in a straight line along the light focusing position of the linear Fresnel lens (6a). The reflector (5) has reflecting surfaces (5c-5f) that surround each of the light sources (4) and constitute a segment. The section of the reflector (5) adjacent to a portion of the planar lighting device (1), where the light source (4) cannot be disposed along the light-focusing position due to the planar shape of the light-emitting region of the planar lighting device (1) being a non-rectangular irregular shape, expands toward the outer edge side of the planar lighting device (1).

Description

Technical Field

[0001] The invention relates to a planar lighting device. Background Art

[0002] A direct-type planar lighting device having a linear Fresnel lens has been proposed (for example, see Patent Document 1, etc.) The use of a linear Fresnel lens can achieve efficient light distribution, high brightness, high brightness uniformity, low power consumption, and thinness.

[0003] Furthermore, a planar light source has been proposed that suppresses uneven brightness that occurs in the periphery when the planar shape (light-emitting surface shape) is an irregular shape (for example, refer to Patent Document 2).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: International Publication No. 2022 / 004036

[0007] Patent Document 2: Japanese Patent Application Publication No. 2021-190417 Summary of the invention

[0008] Problems to be solved by the invention

[0009] However, when the planar shape of a direct-type planar lighting device including a linear Fresnel lens is an irregular shape, no research has been conducted on how to eliminate uneven brightness in the irregular-shaped portion, and it is desired to address this problem.

[0010] That is, in a direct-down type planar lighting device equipped with a linear Fresnel lens, it is necessary to arrange light sources such as LEDs (Light Emitting Diodes) in a straight line along the light-collecting position (focal position) of the linear Fresnel lens. However, when the planar shape of the light-emitting area is a non-rectangular irregular shape, it is difficult to arrange the light source in a straight line along the light-collecting position of the linear Fresnel lens to the end of the light-emitting area due to the structural constraints of the frame portion, which will cause a dark area to reduce the brightness uniformity.

[0011] The present invention has been made in view of the above situation, and an object of the present invention is to provide a planar lighting device that can prevent the occurrence of dark areas in irregular-shaped parts and improve brightness uniformity.

[0012] Solutions for solving problems

[0013] In order to solve the above problems and achieve the purpose, a planar lighting device of one embodiment of the present invention is a direct-down type planar lighting device with a linear Fresnel lens, and is provided with a plurality of light sources and a reflector. The plurality of light sources are arranged on a substrate in a straight line along the light-converging position of the linear Fresnel lens. The reflector has a reflecting surface that surrounds each of the light sources and forms a segment. In a portion of the planar lighting device where the light source cannot be arranged along the light-converging position because the planar shape of the light-emitting area is a non-rectangular irregular shape, the segment of the reflector adjacent to the portion extends toward the outer edge of the planar lighting device.

[0014] A planar lighting device according to one embodiment of the present invention can prevent a dark portion from being generated in an irregular-shaped portion, thereby improving brightness uniformity. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a perspective view of the appearance of a planar lighting device according to one embodiment.

[0016] Figure 2 This is an exploded perspective view of the main parts of the planar lighting device.

[0017] Figure 3 is a top view of the reflector.

[0018] Figure 4 This is a diagram schematically showing a light emitting area of ​​a planar lighting device and a focusing position where a light source is arranged.

[0019] Figure 5 is with Figure 4 A cross-sectional view of the planar lighting device corresponding to the X-X section.

[0020] Figure 6 This is an enlarged view of the extended portion of the condenser lens.

[0021] Figure 7 FIG. 1 is a diagram showing an example in which a planar lighting device according to a comparative example has a dark portion due to a planar shape that is not a rectangular shape.

[0022] Figure 8 FIG. 2 is a diagram showing an example in which a planar lighting device according to a comparative example has a dark portion due to its planar shape being a non-rectangular irregular shape.

[0023] Fig. 9 It is a diagram showing an example of a light emitting area of ​​a planar lighting device according to a comparative example and a light focusing position where a light source is arranged.

[0024] Fig.10 is with Fig. 9 A cross-sectional view of the planar lighting device corresponding to the X-X section. DETAILED DESCRIPTION

[0025] Hereinafter, the planar lighting device of the embodiment will be described with reference to the accompanying drawings. It should be noted that the present invention is not limited to the present embodiment. In addition, the dimensional relationship of each element in the drawings, the proportion of each element, etc. may sometimes be different from the actual one. Sometimes the drawings may include parts with different dimensional relationships and proportions. In addition, the contents described in one embodiment or variant example are also applicable to other embodiments and variant examples in principle.

[0026] Figure 1 1 is a perspective view of the appearance of a planar lighting device 1 according to an embodiment. In the figure, for convenience, the long dimension direction of the planar lighting device 1 is set as the X-axis direction, the short dimension direction is set as the Y-axis direction, and the thickness direction is set as the Z-axis direction, but the posture when used is arbitrary.

[0027] Figure 1 In the figure, the planar lighting device 1 has a roughly rectangular (can also be roughly square) and roughly plate-shaped appearance, and is composed of a bottom frame with a bottom box shape (hidden behind the figure) that accommodates the substrate described later, etc., and a top frame 9 that covers the opening side of the bottom frame to form a shell. In the top frame 9, an exit surface 1a (light-emitting area) is formed through a roughly rectangular opening 9a, and light is irradiated from the inside of the planar lighting device 1 to the outside. In the figure, the internal optical sheet 8 is exposed on the exit surface 1a. The details of the shape (special shape) of the opening 9a (exit surface 1a) will be described later. In the case where the planar lighting device 1 is used as a backlight for a vehicle-mounted display such as a cluster meter, CID (Center Information Display), head-up display, indicator, etc., a liquid crystal display device or the like is attached to the side of the exit surface 1a.

[0028] Figure 2 is an exploded perspective view of the main parts of the planar lighting device 1. Figure 1 The same is true for the diagram when viewed from the emission surface side. Figure 2 In the figure, the planar lighting device 1 is in the following shape: a substrate 3 equipped with a plurality of (many) light sources 4, a reflector 5, a focusing lens 6, a light distribution / field of view adjustment lens 7 and an optical sheet 8 are assembled on a bottom frame 2, and a top frame 9 is embedded in the outer side of the bottom frame 2 to form a cover.

[0029] The bottom frame 2 has a bottom and side walls on four sides of the outer periphery of the bottom. The bottom frame 2 is formed by die casting, sheet metal, etc. On the inner side of the bottom of the bottom frame 2, a substrate 3 is fixed via a fixing member (not shown) composed of double-sided tape or the like. On the substrate 3, a plurality (many) of light sources 4 composed of LEDs (Light Emitting Diodes) or the like are arranged in a grid shape, for example. The plurality of light sources 4 can be driven by local dimming and are electrically connected in a manner that allows them to be lit individually. In addition, by adjusting the luminous intensity of each light source 4, the brightness uniformity can be further improved.

[0030] The back side of the reflector 5 is fixed between the light sources 4 on the substrate 3 via a plurality of short strip-shaped fixing members (not shown) made of double-sided tapes extending in the left-right direction (or the up-down direction) of the figure. The reflector 5 has a reflecting surface surrounding each light source 4, and is used to reflect the light emitted from the light source 4 at a wide angle to the exit surface side to increase the brightness. The reflector 5 is manufactured by injection molding of synthetic resin or the like.

[0031] The condenser lens 6 disposed on the exit side of the reflector 5 condenses the light incident from the light source 4 side into substantially parallel light, and for example, a linear Fresnel lens having concave-convex grooves extending in the long dimension direction (X-axis direction) is provided on its exit surface. The linear Fresnel lens may also be provided on the incident surface of the condenser lens 6. The linear Fresnel lens has concave-convex grooves arranged in the short dimension direction (Y-axis direction) corresponding to the inclined portion of the curved surface of a convex lens (cylindrical lens), and is periodically arranged according to the number of light sources 4 (arranged in the short dimension direction).

[0032] The light distribution / field of view adjustment lens 7 disposed on the exit side of the focusing lens 6 changes the optical axis of the exit light of each portion on the exit surface within the Y-Z plane (optical axis tilt, peak shift), and adjusts the diffusion of each portion in the Y-axis direction. The light distribution / field of view adjustment lens 7 has, on either the incident surface or the exit surface, for example, a plurality of (many) tiny prisms with concave-convex grooves extending in the X-axis direction and a plurality of (many) tiny biconvex lenses with concave-convex grooves extending in the X-axis direction. These prisms and biconvex lenses may also be integrated into a composite lens. In addition, in the case where a composite lens is provided on one surface, a plurality of (many) tiny biconvex lenses with concave-convex grooves extending in the orthogonal Y-axis direction and adjusting the diffusion and brightness uniformity in the X-axis direction may be provided on the other surface.

[0033] The optical sheet 8 disposed on the exit side of the light distribution / viewing range adjustment lens 7 is a diffusion sheet or a polarized reflective sheet, but is not limited thereto. For example, the optical sheet 8 may also be a prism sheet or a louver sheet. The diffusion sheet diffuses the light passing through. The polarized reflective sheet allows polarized light in a specified direction to pass through and reflects polarized light in a direction orthogonal to the specified direction.

[0034] The top frame 9 is disposed on the light-emitting surface side of the optical sheet 8, and the top frame 9 is fixed to the bottom frame 2. The top frame 9 is formed of a resin, a metal plate, or the like.

[0035] It should be noted that, although the planar lighting device 1 is shown in the figure as being planar, the planar lighting device 1 may also be curved.

[0036] Figure 3 is a top view of the reflector 5 . Figure 3 In the embodiment, the outer side of the reflector 5 is surrounded by a side wall 5a, and the inner side of the reflector 5 is set as a section for each light source 4. Each section has a roughly rectangular opening 5b configured to expose the light source 4 and a plurality of inclined reflecting surfaces 5c, 5d, 5e, 5f surrounding the opening 5b and opening toward the exit surface side. In addition, the reflector 5 is an irregular shape that bulges outward with the central part as the center over the substantially entire length of the upper side. The reflecting surface of the irregular portion whose planar shape on the upper side is non-rectangular is extended toward the outer edge side as an extension portion 5g. It should be noted that in the present embodiment, the reflecting surface is inclined on the basis of setting the opening of the irregular portion to the same shape as the opening 5b other than the irregular portion, thereby providing the extension portion 5g. That is, the plurality of openings 5b of the reflector 5 through which the light source 4 is exposed include irregular portions, and are arranged in the same shape and in a grid shape, and the reflecting surface on the outer edge side of the irregular portion is adjusted in a manner corresponding to the shape of the outer edge of the irregular portion. In other words, Figure 3In the embodiment, the ridges formed by the reflecting surfaces 5d and 5f extend linearly in one direction (Y direction), the ridges formed by the reflecting surfaces 5c and 5e extend linearly in a direction orthogonal to one direction (X direction), and only the ridges of the extension portion 5g extend non-linearly (the valley line at the root is linear). By setting such a structure, it is easy to mold the reflector 5 (make a mold for molding the reflector 5). In addition, the reflecting surface can be made as close to the light source 4 as possible in the irregular part, so that the reduction in brightness can be suppressed. It should be noted that the extension portion 5g can also be composed of more than two surfaces, for example, it can also include an inclined surface and a surface extending approximately parallel to the Z axis. At least a part of the irregular part (for example, on the opening 9a side of the inclined surface) includes a surface extending approximately parallel to the Z axis along the shape of the outer edge, thereby making the inclination angle of the reflecting surface in the extension portion 5g constant throughout the entire length, and making it easier to mold the reflector 5 (make a mold for molding the reflector 5). In addition, in addition to the shape of the opening 9a (exit surface 1a, light-emitting area) that can be applied to the present embodiment, it can also be applied to the case where, for example, a part of one side or multiple sides of the outer edge of the rectangular opening include a circular arc portion, a straight line portion that is not parallel to the grid. The irregular portion is not limited to a shape that bulges outward, but can also be a shape that is recessed inward. Moreover, instead of setting the opening of the irregular portion to the same shape as the opening 5b outside the irregular portion, it is also possible to set an expansion portion 5g on the basis of enlarging the opening of the irregular portion.

[0037] Figure 4 It is a diagram schematically showing a light emitting area of ​​the planar lighting device 1 and a light focusing position where a light source is arranged. Figure 4 In the figure, the outer shape shown by the dotted line represents the luminous area. Here, the central part of the upper side is a convex shape bulging outward. In addition, the multiple single-point dashed lines extending in the horizontal direction (X-axis direction) of the figure are the focusing positions (focal positions) of the linear Fresnel lens 6a, and the light source 4 is arranged at the focusing position. It should be noted that the focusing position (focal position) of the linear Fresnel lens 6a and the position of the light source 4 arranged in a straight line are not only consistent, but it can also be that the focusing position and the position of the light source 4 are parallel in a slightly separated state. For example, the central axis of the linear Fresnel lens 6a (the focusing position of the linear Fresnel lens 6a extending in a straight line) is relatively offset relative to the optical axis of the light source 4 in the plane perpendicular to the optical axis in the direction in which the prisms of the linear Fresnel lens 6a are arranged, thereby making the light emitted from the linear Fresnel lens 6a tilt relative to the optical axis of the light source 4 toward the direction in which the prisms of the linear Fresnel lens 6a are arranged.

[0038] Figure 5 is with Figure 4 The XX section of FIG. 1 is a cross-sectional view of the planar lighting device 1 , in which the bottom frame 2 , the light distribution / viewing range adjustment lens 7 , the optical sheet 8 , and the top frame 9 are omitted from the illustration. Figure 5 In the figure, except for the irregular part on the right, the positions of the reflective surfaces 5c and 5e of the reflector 5 in each section relative to each light source 4 are roughly the same, but in the irregular part on the right, the removal part 5h is removed from the outer reflective surface to form an extended part 5g. As a result, there is no removal part 5h that obstructs the light from the light source 4 adjacent to the irregular part, and the light reaches the end of the light-emitting area, preventing the irregular part from generating a dark part and improving the brightness uniformity.

[0039] In addition, the linear Fresnel lens 6a of the condenser lens 6 located on the exit surface side of the extension part 5g is different from other parts, and the prism is extended outward to form a continuous extension part 6b. Therefore, the condensing function is maintained at the end of the light emitting area, and the brightness uniformity is further improved.

[0040] Figure 6 This is an enlarged view of the extended portion 6b of the condenser lens 6. The extended portion 6b of the prism is extended in a manner corresponding to the convex lens curved surface L of the cylindrical lens corresponding to the linear Fresnel lens 6a. That is, the other parts in the segment become the parts corresponding to the partial curved surface L1 in the convex lens curved surface L, and the extended portion 6b becomes the part corresponding to the partial curved surface L2 continuous with the partial curved surface L1. As a result, the condensing by the linear Fresnel lens 6a is also continuous in the irregular part, preventing the occurrence of unevenness and further improving the brightness uniformity.

[0041] Figure 7 1 is a diagram showing an example in which a dark portion DA is generated in a planar illumination device 1 ′ according to a comparative example because the planar shape is a non-rectangular irregular shape. Figure 7 In the figure, the area surrounded by the dotted line is the light-emitting area of ​​the planar lighting device 1', and the upper side in the figure is a non-rectangular irregular shape. In addition, the small quadrilaterals represent segments, Figure 7 In the embodiment, a portion protruding due to an irregular shape is generated on the outer side of the upper side of the segments arranged in the upper side in the horizontal direction. In the portion protruding due to the irregular shape, due to the structural constraints of the frame portion, it is difficult to arrange the light source in a straight line along the focusing position of the linear Fresnel lens (even if a linear Fresnel lens can be installed). In addition, since each segment is surrounded by a reflective surface, light is not supplied to the irregular shape portion on the upper side, forming a dark area DA, which reduces the brightness uniformity.

[0042] Figure 8 1 is a diagram showing another example in which a dark portion DA is generated due to the planar lighting device 1 ′ of the comparative example having a non-rectangular planar shape. Figure 8 In this case, in several segments at both ends (three at each end in the example shown in the figure), it is difficult to arrange the light source along the focusing position of the linear Fresnel lens due to the structural constraints of the frame portion, so dark areas DA are generated at both ends.

[0043] Fig. 9 is a diagram showing an example of a light emitting area and a light focusing position where a light source is arranged in a planar lighting device 1' of a comparative example, and Figure 7 The configuration of the light-emitting area and segment corresponds. Fig. 9 The multiple single-dot chain lines extending in the lateral direction (X-axis direction) in φ are the light-collecting positions (focal positions) of the linear Fresnel lens 6 a ′, and the light source 4 ′ is arranged at the light-collecting position.

[0044] Fig.10 is with Fig. 9 The XX section of FIG. 1 is a cross-sectional view of the planar lighting device 1 ′ corresponding to the cross-section thereof, wherein the bottom frame, the light distribution / viewing range adjustment lens, the optical sheet, and the top frame are omitted from the illustration. Fig.10 In the embodiment, a plurality of light sources 4' are arranged on a substrate 3', and a reflector 5' is arranged on the light-emitting side thereof. Each light source 4' is exposed from an opening 5b', and reflecting surfaces 5c' and 5e' are connected to both sides of the opening 5b'.

[0045] Fig.10 In each section, the reflective surfaces 5c' and 5e' of the reflector 5' are in the same position relative to each light source 4'. Therefore, in the irregular part on the right, due to the reflective surface 5e' and the frame connected thereto, the light will not reach the end of the luminous area, forming a dark portion DA.

[0046] For this, Figure 5 In the planar lighting device 1 of the embodiment, in the irregular portion on the right side, the removal portion 5h is removed from the outer reflective surface to form an extended portion 5g. That is, in the portion of the planar lighting device 1 where the light source 4 cannot be arranged at the focusing position (of the imaginary linear Fresnel lens) because the plane shape of the light-emitting area is a non-rectangular irregular shape (due to lack of space or small space), the section of the reflector 5 adjacent to the portion is extended toward the outer edge of the planar lighting device 1. Therefore, the light from the light source 4 reaches the end of the light-emitting area, preventing the irregular portion from generating a dark portion, and improving the brightness uniformity.

[0047] also, Figure 5 In the planar lighting device 1 of the embodiment, the prism extension portion 6b is provided in the linear Fresnel lens 6a corresponding to the extension portion 5g extended from the removed portion 5h of the reflector 5, so that the focusing function is maintained and the brightness uniformity of the portion that would otherwise become a dark portion is further improved. In addition, as described above, the prism extension portion 6b is provided continuously along the curved surface of the cylindrical lens corresponding to the linear Fresnel lens 6a, so that the generation of unevenness is prevented and the brightness uniformity is further improved.

[0048] also, Figure 5In the planar lighting device 1 of the embodiment, the expansion of the segments toward the outer edge and the expansion of the prisms of the linear Fresnel lens 6a are performed in a direction orthogonal to the direction in which the concavo-convex grooves of the linear Fresnel lens 6a extend. Therefore, the effect of expanding the segments and the effect of expanding the prisms of the linear Fresnel lens 6a are simultaneously achieved.

[0049] Furthermore, another linear Fresnel lens having concavo-convex grooves extending in a direction perpendicular to the direction in which the concavo-convex grooves of the linear Fresnel lens 6 a extend may be provided. This makes it possible to cope with various light distributions.

[0050] Furthermore, the other linear Fresnel lens described above is formed on the surface opposite to the linear Fresnel lens 6a, or is formed separately from the linear Fresnel lens 6a. This improves the degree of freedom in the configuration of the two types of linear Fresnel lenses.

[0051] As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, Various changes are possible as long as they do not deviate from the summary.

[0052] As described above, the planar lighting device of the embodiment is a direct-down type planar lighting device with a linear Fresnel lens, and includes: a plurality of light sources arranged linearly on a substrate along the light-collecting position of the linear Fresnel lens; and a reflector having a reflecting surface that surrounds each of the light sources and forms a segment, and in a portion of the planar lighting device where the light sources cannot be arranged along the light-collecting position because the planar shape of the light-emitting region is a non-rectangular irregular shape, the segment of the reflector adjacent to the portion extends toward the outer edge of the planar lighting device. Thus, dark portions are prevented from being generated in the irregularly shaped portion, and brightness uniformity is improved.

[0053] In addition, in the portion of the planar lighting device where the light source cannot be arranged along the light-focusing position because the plane shape of the light-emitting area is a non-rectangular irregular shape, the prism of the linear Fresnel lens is expanded. Thus, the light-focusing function of the linear Fresnel lens is maintained, and the brightness uniformity of the portion that would otherwise become a dark portion is further improved.

[0054] In addition, the prism of the linear Fresnel lens is expanded in a manner corresponding to the curved surface of the cylindrical lens corresponding to the linear Fresnel lens. Therefore, the light focusing by the linear Fresnel lens is continuous even in the irregular shape, which prevents unevenness and further improves brightness uniformity.

[0055] Furthermore, the expansion of the segment toward the outer edge and the expansion of the prism of the linear Fresnel lens are performed in a direction orthogonal to the direction in which the concavo-convex grooves of the linear Fresnel lens extend, thereby achieving the effect of the expansion segment and the effect of the expansion prism of the linear Fresnel lens at the same time.

[0056] In addition, another linear Fresnel lens is provided, which has concavoconvex grooves extending in a direction perpendicular to the direction in which the concavoconvex grooves of the linear Fresnel lens extend. This can cope with various light distributions.

[0057] Furthermore, the other linear Fresnel lens is formed on a surface opposite to the linear Fresnel lens, or is formed separately from the linear Fresnel lens. Thus, the degree of freedom in the structure of the two types of linear Fresnel lenses is improved.

[0058] In addition, the plurality of openings of the reflector through which the light source is exposed include irregularly shaped portions, and are arranged in a grid-like manner in the same shape, and the reflecting surface on the outer edge side of the irregularly shaped portion is adjusted in a manner corresponding to the shape of the outer edge of the irregularly shaped portion. Thus, it is easy to mold the reflector (make a mold for molding the reflector).

[0059] In addition, in a direct-down type planar lighting device with a linear Fresnel lens, there are: a plurality of light sources arranged linearly on a substrate along a light-converging position of the linear Fresnel lens; and a reflector having a reflecting surface surrounding each of the light sources and forming a segment, wherein the prism of the linear Fresnel lens is extended toward a portion of the planar lighting device where the light sources cannot be arranged along the light-converging position because the plane shape of the light-emitting region is a non-rectangular irregular shape. Thus, a dark portion is prevented from being generated in the irregular portion, and brightness uniformity is improved.

[0060] In addition, the present invention is not limited to the above-mentioned embodiments. The schemes formed by appropriately combining the above-mentioned constituent elements are also included in the present invention. In addition, those skilled in the art can easily derive further effects and variations. Therefore, the more extensive schemes of the present invention are not limited to the above-mentioned embodiments, and various changes can be made.

[0061] Description of Reference Numerals

[0062] 1: planar lighting device; 1a: exit surface; 2: bottom frame; 3: substrate; 4: light source; 5: reflector; 5a: side wall; 5b: opening; 5c~5f: reflecting surface; 5g: extension part; 5h: removal part; 6: focusing lens; 6a: linear Fresnel lens; 6b: extension part; 7: light distribution / field of view adjustment lens; 8: optical sheet; 9: top frame; 9a: opening.

Claims

1. A planar lighting device, which is a direct-down type planar lighting device with a linear Fresnel lens, wherein: The planar lighting device comprises: A plurality of light sources are arranged on the substrate in a straight line along the focusing position of the linear Fresnel lens; as well as a reflector having a reflecting surface surrounding each of the light sources and forming a segment, In a portion of the planar lighting device where the light source cannot be arranged along the light-collecting position because the planar shape of the light-emitting region is a non-rectangular irregular shape, the segment of the reflector adjacent to the portion extends toward the outer edge of the planar lighting device.

2. The planar lighting device according to claim 1, wherein: The prism of the linear Fresnel lens is expanded in a portion of the planar lighting device where the light source cannot be arranged along the light-collecting position because the planar shape of the light-emitting region is a non-rectangular irregular shape.

3. The planar lighting device according to claim 2, wherein: The expansion of the prisms of the linear Fresnel lens is performed in a manner corresponding to the curved surface of the cylindrical lens corresponding to the linear Fresnel lens.

4. The planar lighting device according to claim 2, wherein: The expansion of the segments toward the outer edge side and the expansion of the prisms of the linear Fresnel lens are performed in a direction orthogonal to a direction in which the concavo-convex grooves of the linear Fresnel lens extend.

5. The planar lighting device according to claim 1, wherein: The planar lighting device includes another linear Fresnel lens having a concave-convex groove extending in a direction orthogonal to a direction in which the concave-convex groove of the linear Fresnel lens extends.

6. The planar lighting device according to claim 5, wherein: The other linear Fresnel lens is formed on a surface opposite to the linear Fresnel lens, or is formed separately from the linear Fresnel lens.

7. The planar lighting device according to claim 1, wherein: The plurality of openings of the reflector through which the light source is exposed include irregularly shaped portions and are arranged in a grid shape in the same shape, and the reflecting surfaces on the outer edge sides of the irregularly shaped portions are adjusted to correspond to the shapes of the outer edges of the irregularly shaped portions.

8. A planar lighting device, which is a direct-down type planar lighting device having a linear Fresnel lens, wherein: The planar lighting device comprises: A plurality of light sources are arranged on the substrate in a straight line along the focusing position of the linear Fresnel lens; as well as a reflector having a reflecting surface surrounding each of the light sources and forming a segment, In a portion of the planar lighting device where the light source cannot be arranged along the light-collecting position because the planar shape of the light-emitting region is a non-rectangular irregular shape, the prism of the linear Fresnel lens extends toward the portion.

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