Planar lighting device

Abstract

According to the embodiments, a planar lighting device (1) comprises a plurality of light sources (4), respective reflectors (5) that have reflection surfaces that surround the emission sides of the plurality of light sources (4), a condenser lens (6) that is provided on the emission side of the reflectors (5) and condenses light emitted from the plurality of light sources (4), and a light distribution lens (7) that is provided on the emission side of the condenser lens (6) and causes the light distribution of light condensed by the condenser lens (6) to slant in one direction. Top parts of the reflectors (5) are offset in the one direction from the center positions of adjacent light sources (4).

Description

Planar lighting device

[0001] The present invention relates to a surface lighting device.

[0002] A so-called direct-type planar lighting device is known, which includes a substrate on which multiple light sources are arranged two-dimensionally and a reflector arranged on the substrate and having a reflective surface surrounding the emission sides of each light source. In such a direct-type planar lighting device, light from the light sources is focused by a linear Fresnel lens with concave and convex grooves extending in one direction (e.g., the horizontal direction when the user directly or indirectly views the emission surface), and a peak-shift prism with concave and convex grooves extending in the same direction as the linear Fresnel lens to tilt the optical axis and achieve a narrow light distribution in a direction perpendicular to the grooves (e.g., the vertical direction). Direct-type planar lighting devices equipped with a linear Fresnel lens and a peak-shift prism are used, for example, in head-up displays (HUDs), which require high brightness.

[0003] Japanese Patent Application Laid-Open No. 2022-182454

[0004] Generally, display devices including HUDs are expected to be viewed from two directions, such as the front direction (H=0°) and an oblique direction (e.g., H=30°), and a backlight (planar lighting device) that illuminates a liquid crystal display panel serving as a display device is required to improve the non-uniformity of luminance in each direction while maintaining a good appearance from both directions. For this reason, various improvement methods have been proposed for planar lighting devices, but further improvements are desired.

[0005] The problem to be solved by the present invention is to provide a surface lighting device that can improve the non-uniformity of luminance in each direction while maintaining a good appearance from two directions.

[0006] In order to solve the above-mentioned problems and achieve the object, a surface lighting device according to one aspect of the present invention comprises a plurality of light sources, a reflector having a reflective surface surrounding the emission side of each of the plurality of light sources, a focusing lens arranged on the emission side of the reflector to focus light emitted from the plurality of light sources, and a light distribution lens arranged on the emission side of the focusing lens to tilt the distribution of light focused by the focusing lens in one direction, wherein the top of the reflector is arranged at a position shifted from the center position of two adjacent light sources in the one direction.

[0007] FIG. 1 is a diagram illustrating an example of the configuration of a planar lighting device according to an embodiment. FIG. 2 is a diagram illustrating an example of the behavior of light rays when a reflector according to Comparative Example A is applied. FIG. 3 is a diagram illustrating an example of the behavior of light rays when a reflector according to an embodiment is applied. FIG. 4A is a diagram illustrating a luminance distribution when a reflector according to a Comparative Example is used. FIG. 4B is a diagram illustrating a luminance distribution when a reflector according to an embodiment is used. FIG. 5 is a diagram for explaining the effect of a reflector according to an embodiment. FIG. 6 is a diagram for explaining an asymmetric structure of a condenser lens according to an embodiment. FIG. 7 is a diagram for explaining an asymmetric structure of condenser lenses according to Comparative Examples B1 to B4. FIG. 8A is a diagram illustrating a luminance distribution when a condenser lens according to a Comparative Example is used. FIG. 8B is a diagram illustrating a luminance distribution when a condenser lens according to an embodiment is used. FIG. 9 is a diagram for explaining the effect of a condenser lens according to an embodiment. FIG. 10A is a diagram illustrating a luminance distribution of a planar lighting device according to a Comparative Example. FIG. 10B is a diagram illustrating a luminance distribution of a planar lighting device according to an embodiment. Fig. 11 is a diagram for explaining the effect of the planar lighting device according to the embodiment. Fig. 12A is a diagram illustrating the luminance distribution of the planar lighting device according to the comparative example. Fig. 12B is a diagram illustrating the luminance distribution of the planar lighting device according to the embodiment. Fig. 13 is a diagram for explaining the effect of the planar lighting device according to the embodiment.

[0008] Hereinafter, a surface lighting device according to an embodiment will be described with reference to the drawings. Note that the present invention is not limited to these embodiments. Furthermore, the dimensional relationships and ratios of elements in the drawings may differ from reality. The dimensional relationships and ratios may differ between the drawings. Furthermore, the content described in one embodiment or modification is, in principle, applicable to other embodiments or modifications as well.

[0009] (Basic Configuration) FIG. 1 is a diagram showing an example of the configuration of a surface lighting device 1 according to an embodiment, and is an end view showing the state within the thickness. For convenience, the light-emitting surface of the surface lighting device 1 is in the X-Y plane, and the thickness direction of the surface lighting device 1 is defined as the Z-axis direction. Furthermore, in a usage state in which light emitted from the surface lighting device 1 is incident on a liquid crystal panel (not shown) or the like attached to the surface lighting device 1 and is visible to a user, the X-axis direction corresponds to the horizontal direction (H) and the Y-axis direction corresponds to the vertical direction (V). Specifically, in a usage state of the surface lighting device 1, the positive direction of the Y-axis corresponds to the "upper side" and the negative direction of the Y-axis corresponds to the "lower side." Note that the usage state of the surface lighting device 1 is not limited to the above-mentioned direction, and the surface lighting device 1 can be used in any direction.

[0010] In this embodiment, the surface lighting device 1 is assumed to be viewed from two directions, namely, the front direction (H=0°) and the diagonal direction (H=30°), and the case where the optical axis of the emitted light is tilted (peak shifted) in the V=-12° direction is described, but the present invention is not limited to this.

[0011] As shown in FIG. 1, the surface lighting device 1 includes a bottom frame 2 , a substrate 3 , a light source 4 , a reflector 5 , a condenser lens 6 , a light distribution lens 7 , and a reflective polarizing film 8 .

[0012] The bottom frame 2 is a substantially box-shaped member with a bottom that houses the substrate 3 (described later) and other components. The bottom frame 2 is fitted with a top frame (not shown) that has an opening for emitting light, thereby forming the exterior of the surface illumination device 1. Although not described in detail, the bottom frame 2 is appropriately provided with structures (projections, holes, etc.) for housing the substrate 3 and other components, connectors for electrical connection, etc.

[0013] The substrate 3 is a member provided at the bottom of the bottom frame 2 and equipped with electronic components such as a light source 4, which will be described later.

[0014] The light sources 4 are configured with LEDs (Light Emitting Diodes) or the like, and a plurality of them are arranged two-dimensionally (for example, in a grid pattern) on the substrate 3. The light sources 4 are preferably those having a light distribution pattern known as a top hat type. Each of the plurality of light sources 4 is driven individually, and can support so-called local dimming drive.

[0015] The reflector 5 is disposed on the side of the substrate 3 where the light sources 4 are disposed, and includes a reflective wall 51 extending along the Y-axis direction and a reflective wall 52 extending along the X-axis direction. The reflective walls 51 and 52 of the reflector 5 are disposed at equal intervals between each of the plurality of light sources 4, thereby forming a reflective surface that rectangularly surrounds the emission side of each of the light sources 4. This improves contrast when the plurality of light sources 4 are driven using local dimming. Note that the unit area into which the individual light sources 4 are separated by the reflector 5 is referred to as a "segment (or zone)." The height of the reflector 5 can be set arbitrarily, but it is preferable that the reflective wall 52 be higher than the reflective wall 51, as shown in the figure, to reduce stray light.

[0016] Here, the apex of the reflector 5 according to the embodiment is disposed at a position offset in the Y-axis direction from the center positions of the two adjacent light sources 4, and the reflective surfaces 52a and 52b have different inclination angles (absolute values) with respect to the optical axis (axis parallel to the Z-axis). For example, the reflective surface 52a is configured to have a smaller inclination angle than the reflective surface 52b, so that the apex of the reflector 5 is disposed at a position offset toward the negative Y-axis direction (downward). Note that configuration examples of the reflector 5 will be described in detail later.

[0017] The condenser lens 6 is an optical element disposed on the exit side of the reflector 5 and condenses light from the light source 4 in the Y-axis direction. For example, the condenser lens 6 is an optical element having a lenticular lens with concave and convex grooves extending along the Y-axis direction in the incident surface, and a linear Fresnel lens with concave and convex grooves extending along the X-axis direction in the exit surface. The linear Fresnel lens has grooves formed periodically to match the spacing (pitch) between the multiple light sources 4.

[0018] Here, the linear Fresnel lens of the condenser lens 6 according to the embodiment is an asymmetric Fresnel lens having different defocus ratios depending on the region in the Y-axis direction. An example of the configuration of the condenser lens 6 will be described in detail later.

[0019] The light distributing lens 7 is an optical element that is disposed on the exit side of the condensing lens 6 and tilts the light distribution in the Y-axis direction (peak shift in the V=-12 deg direction) of the light condensed by the condensing lens 6. For example, the light distributing lens 7 has a peak shift prism with concave and convex grooves extending along the X-axis direction in the incident surface, and a lenticular lens with concave and convex grooves extending along the Y-axis direction in the exit surface.

[0020] The light distribution lens 7 may be a composite prism that combines the function of a linear prism that tilts light and the function of a lenticular lens that spreads light, as disclosed in, for example, JP 2023-127243 A.

[0021] The reflective polarizing film 8 is an optical component disposed on the output side of the light distributing lens 7, and enhances the brightness of the output light. The reflective polarizing film 8 is formed, for example, from a substantially plate-shaped DBEF (Dual Brightness Enhancement Films) or the like, and has polarization that matches the liquid crystal panel provided on the output side of the planar lighting device 1.

[0022] (Configuration of Reflector 5) The reflector 5 has an asymmetric shape in which the inclination angles of a pair of reflective surfaces (reflective surface 52a and reflective surface 52b) in the Y-axis direction (the direction in which the light distribution is inclined by the peak shift prism) are different from each other. Specifically, the inclination angle of reflective surface 52a (corresponding to the first reflective surface) is configured to be smaller than the inclination angle of reflective surface 52b (corresponding to the second reflective surface), so that the apex of the reflector 5 is positioned shifted toward the negative Y-axis direction (downward). This is expected to increase the dominance of light that is incident on the light distributing lens 7 during segment S and that travels downward (toward the negative Y-axis direction, the side in which the light distribution is inclined by the peak shift prism), thereby increasing brightness.

[0023] Here, we will explain the behavior of light rays when using the reflector 5' according to comparative example A. The reflector 5' has a shape that is symmetrical in the Y-axis direction, and the inclination angles of a pair of reflecting surfaces are the same (the absolute values ​​of the angles are the same).

[0024] Fig. 2 is a diagram showing an example of the behavior of light rays when the reflector 5' according to Comparative Example A is used. Fig. 2 illustrates the behavior of light rays that arrive at the segment S directly from the light source 4 without passing through the reflector 5'.

[0025] As shown in FIG. 2 , in order to shift the peak in the V=−12° direction, the multiple principal surfaces 71 of the light distributing lens 7 are not symmetrical with respect to the optical axis of the light source 4 but are tilted in one direction with respect to the Y-axis direction (the up-down direction in the figure), with the tilt angle being constant in the Y-axis direction. Therefore, the difference in behavior between light rays traveling below the optical axis of the light source 4 and light rays traveling above the optical axis becomes greater as they approach the edge of segment S. For example, if light from the light source 4 is collected somewhat defocused by the condensing lens 6 with priority given to uniformity, light rays traveling from the light source 4 toward the edge of the reflector 5′ located above (the edge of segment S) may be incident on the rising surface 72 of the light distributing lens 7 rather than the principal surface 71 because they are directed somewhat upward after passing through the condensing lens 5. In this case, the light distribution performance of the light distributing lens 7 is not properly exhibited. Furthermore, even if the incident light is incident on the principal surface 71, if the incident light is not parallel to the optical axis, the peak cannot be accurately shifted in the desired direction (the V=−12° direction). Furthermore, light rays traveling from the light source 4 toward the edge of the reflector 5' located below (the edge of segment S) travel somewhat downward via the condenser lens 6, and although this makes it easier for the light to be incident on the main surface 71 of the light distributing lens 7, it causes the peak to be shifted somewhat downward from the desired direction. These phenomena combine, and as a result, the light distribution of the light emitted by the light source 4 is superimposed on this, and it is thought that this results in the appearance of bright lines and dark lines (dark areas) at the edge of segment S.

[0026] 3 is a diagram illustrating an example of the behavior of light rays when the reflector 5 according to the embodiment is applied. FIG. 3 illustrates the behavior of light rays that reach the segment S directly without passing through the reflector 5.

[0027] As shown in Figure 3, the light rays traveling from the light source 4 toward the edge of the reflector 5 (the edge of the segment S) are such that, compared to Figure 2, the light traveling upward is inferior and the light traveling downward is dominant because the top of the reflector 5 is shifted downward. As a result, the dominance of light incident on the main surface 71 can be increased over light incident on the raised surface 72, and it is expected that the light distribution performance of the light distribution lens 7 will be properly exhibited, and bright lines and dark lines at the edge of the segment S will be improved.

[0028] FIG. 4A is a diagram illustrating a luminance distribution when a reflector according to a comparative example is used. FIG. 4B is a diagram illustrating a luminance distribution when a reflector according to the embodiment is used. FIG. 5 is a diagram for explaining the effect of the reflector 5 according to the embodiment. FIG. 4A illustrates a luminance distribution in an oblique direction (H=30°) when a reflector 5′ is applied. FIG. 4B illustrates a luminance distribution in an oblique direction (H=30°) when a reflector 5 is applied. FIG. 5 illustrates a comparison result of relative luminance at the V cross section of FIGS. 4A and 4B. Note that a condenser lens 6, which will be described later, is not applied in FIGS. 4A, 4B, and 5.

[0029] As a result, as shown by the arrow in FIG. 5, it was found that the dark area that occurred in the segment S when the reflector 5' was applied was improved by applying the reflector 5 according to the embodiment.

[0030] The configuration in which the apex of the reflector is shifted downward can be achieved not only by making the inclination angle of the reflective surface 52a smaller than the inclination angle of the reflective surface 52b. For example, the apex of a reflector having a shape symmetrical with respect to the Y-axis direction (i.e., a reflector having the same shape as the reflector 5') may be shifted downward from the center position of two adjacent light sources 4. This is expected to increase the dominance of light directed downward (toward the negative Y-axis direction), thereby increasing brightness.

[0031] (Configuration of condenser lens 6) The condenser lens 6 has an asymmetric linear Fresnel lens with a different defocus ratio depending on the region in the Y-axis direction. This allows an appropriate defocus ratio to be set depending on the region, which is expected to have the effect of improving the luminance distribution in each region.

[0032] Fig. 6 is a diagram for explaining the asymmetric structure of the collecting lens 6 according to the embodiment. Fig. 6 also illustrates a configuration related to the explanation of the asymmetric structure of the collecting lens 6. The arrows between the collecting lens 6 and the light distributing lens 7 represent light rays, and the direction of the arrows (the angle with respect to the optical axis of the light source 4) represents the defocus ratio (degree of light concentration) of the collecting lens 6. In Fig. 6, the distance between the collecting lens 6 and the light distributing lens 7 is widened in order to illustrate the arrows indicating the light rays.

[0033] 6 , the linear Fresnel lens of the collecting lens 6 has different defocus rates in a region 61 below the optical axis and a region 62 above the optical axis, and is specifically configured so that the defocus rate in region 61 is smaller than the defocus rate in region 62. Therefore, the light emitted from region 61 has a higher degree of concentration than the light emitted from region 62. Note that a high degree of concentration means that the angle of incidence with respect to the imaginary principal plane of the light distributing lens 7 is closer to perpendicular.

[0034] Here, the asymmetric structure of the condenser lens 6 is based on the verification results of comparative examples B1 to B4 in which the defocus ratio of each region is changed.

[0035] FIG. 7 is a diagram illustrating the asymmetric structure of the collecting lenses according to comparative examples B1 to B4. FIG. 7 also illustrates a configuration related to the explanation of the asymmetric structure of the collecting lens 6. The arrows (dashed and solid lines) between the collecting lens 6 and the light distributing lens 7 represent light rays, and the direction (angle) of the arrows represents the defocus ratio (degree of light concentration) of the collecting lens 6. Of these, the dashed arrows represent light rays collected at a typical defocus ratio, while the solid arrows represent light rays collected at a defocus ratio changed (set) in the comparative example. In FIG. 7, the distance between the collecting lens 6 and the light distributing lens 7 is widened in order to illustrate the arrows indicating the light rays.

[0036] 7, the collecting lens 6-1 according to Comparative Example B1 has an increased defocus ratio in the upper (non-tilt direction) region. The collecting lens 6-2 according to Comparative Example B2 has a decreased defocus ratio in the upper (non-tilt direction) region. The collecting lens 6-3 according to Comparative Example B3 has an increased defocus ratio in the lower (tilt direction) region. The collecting lens 6-4 according to Comparative Example B4 has a decreased defocus ratio in the lower (tilt direction) region.

[0037] Table 1 shows the results of verification of the luminance distribution in the front direction (H=0 deg) and in the oblique direction (H=30 deg) using the condenser lenses according to the comparative examples B1 to B4 shown in FIG.

[0038]

[0039] As shown in Table 1, in Comparative Example B1, the brightness distribution in the oblique direction improved, but the brightness distribution in the front direction deteriorated, resulting in prominent dark lines. In Comparative Example B2, the brightness and dark lines in the brightness distribution in the front direction improved, but the brightness distribution in the oblique direction deteriorated, resulting in the dark areas becoming particularly large. In Comparative Example B3, the brightness distribution in both the front direction and the oblique direction deteriorated, resulting in prominent bright lines in the front direction. In Comparative Example B4, the brightness distribution in the front direction improved, the bright lines were weakened, and the impact on the brightness distribution in the oblique direction was also small.

[0040] From the results in Table 1, a condenser lens 6 was found that includes a linear Fresnel lens with an asymmetric structure (a structure in which the defocus ratio is asymmetric with respect to a virtual plane including the optical axis of the light source) in which the defocus ratio in region 61 is smaller than a general value and the defocus ratio in region 62 is approximately the same as a general value. Note that the "general defocus ratio" will vary depending on the configuration of other optical members, but it is preferable to derive it as a value that results in a suitable luminance distribution when a linear Fresnel lens having a constant defocus ratio in the Y-axis direction is used.

[0041] FIG. 8A is a diagram illustrating a luminance distribution when a condensing lens according to a comparative example is used. FIG. 8B is a diagram illustrating a luminance distribution when a condensing lens according to an embodiment is used. FIG. 9 is a diagram for explaining the effect of the condensing lens 6 according to an embodiment. FIG. 8A illustrates a luminance distribution in the front direction (H=0°) when the condensing lens 6′ is applied. FIG. 8B illustrates a luminance distribution in the front direction (H=0°) when the reflector 5 is applied. FIG. 9 illustrates a comparison result of relative luminance at the V cross section of FIGS. 8A and 8B. The condensing lens 6′ is an optical element having a lenticular lens similar to the condensing lens 6 and a linear Fresnel lens having a constant defocus ratio in the Y-axis direction. The reflector 5 is not applied in FIGS. 8A, 8B, and 9.

[0042] As a result, as shown by the arrows in FIG. 9, it was found that the dark lines that appeared in the segment S when the condenser lens 6' was applied were improved by applying the condenser lens 6 according to the embodiment.

[0043] (Effects of Planar Illumination Device 1) Fig. 10A is a diagram illustrating the luminance distribution of a planar illumination device according to a comparative example. Fig. 10B is a diagram illustrating the luminance distribution of a planar illumination device according to an embodiment. Fig. 11 is a diagram for explaining the effects of the planar illumination device according to an embodiment. Fig. 12A is a diagram illustrating the luminance distribution of a planar illumination device according to a comparative example. Fig. 12B is a diagram illustrating the luminance distribution of a planar illumination device according to an embodiment. Fig. 13 is a diagram for explaining the effects of the planar illumination device 1 according to an embodiment. In Figs. 10A to 13, the planar illumination device 1 according to the embodiment is configured to include the reflector 5 and condensing lens 6 described above, and the comparative example is configured without the reflector 5 and condensing lens 6, that is, is configured to include a reflector 5' and a condensing lens 6'.

[0044] Fig. 10A illustrates the luminance distribution in the front direction (H = 0°) of a surface lighting device according to a comparative example. Fig. 10B illustrates the luminance distribution in the front direction (H = 0°) of the surface lighting device 1. Fig. 11 illustrates a comparison result of relative luminance in the V cross section of Figs. 10A and 10B. Fig. 12A illustrates the luminance distribution in the oblique direction (H = 30°) of a surface lighting device according to a comparative example. Fig. 12B illustrates the luminance distribution in the oblique direction (H = 30°) of the surface lighting device 1. Fig. 13 illustrates a comparison result of relative luminance in the V cross section of Figs. 12A and 12B.

[0045] As a result, as shown in the circled areas in Figures 11 and 13, it was found that by applying the reflector 5 and the condenser lens 6, the brightness of the dark areas that occurred in the comparative example was improved, with an improvement of approximately 1%.

[0046] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present invention.

[0047] As described above, the planar lighting device according to the embodiment includes a plurality of light sources, a reflector having a reflective surface surrounding the emission side of each of the plurality of light sources, a condensing lens disposed on the emission side of the reflector for condensing light emitted from the plurality of light sources, and a light distributing lens disposed on the emission side of the condensing lens for tilting the distribution of light condensed by the condensing lens in one direction, wherein the apex of the reflector is positioned at a position offset from the center positions of two adjacent light sources in the one direction. This allows the planar lighting device to achieve a good appearance from two directions while improving the uniformity of brightness in each direction. For example, the planar lighting device can increase the dominance of light incident on the light distributing lens in one direction (e.g., downward / negative Y-axis direction) during segmentation, thereby increasing brightness.

[0048] Furthermore, the apex of the reflector is positioned at a position offset from the center position of the two adjacent light sources in the tilt direction (e.g., downward / negative Y-axis direction) of the light distribution lens. This allows the surface lighting device to enhance the dominance of light directed in the tilt direction of the light distribution lens (peak shift prism), thereby making it possible to demonstrate the light distribution performance of the light distribution lens and improve bright lines and dark lines at the edges of the segments S.

[0049] The reflector has a pair of reflecting surfaces with different inclination angles, which allows the planar lighting device to increase the dominance of light that is incident on the light distribution lens in one direction (e.g., downward / negative Y-axis direction) during segmentation, thereby increasing brightness.

[0050] In addition, the angle of inclination of the first reflecting surface of the reflector, which is located on the side of the inclination direction of the light distributing lens, relative to the optical axis, is smaller than the angle of inclination of the second reflecting surface, which is located on the opposite side of the first reflecting surface, relative to the optical axis. This allows the surface lighting device to increase the dominance of light that is directed in the inclined direction among the light that enters the light distributing lens during segmentation, thereby increasing brightness.

[0051] The condenser lens is an asymmetric Fresnel lens with a different defocus ratio depending on the region, which allows the surface illumination device to set an appropriate defocus ratio depending on the region, thereby improving the luminance distribution in each region.

[0052] The condenser lens has a small defocus ratio in the region on the tilt direction side of the light distribution lens, which allows the surface illumination device to weaken the bright lines in the region on the tilt direction side (lower side).

[0053] In addition, a surface lighting device according to an embodiment includes a plurality of light sources, a reflector having an inclined reflective surface surrounding the emission side of each of the plurality of light sources, a condensing lens disposed on the emission side of the reflector for condensing light emitted from the plurality of light sources, and a light distributing lens disposed on the emission side of the condensing lens for tilting the distribution of light condensed by the condensing lens in one direction, the condensing lens being an asymmetric Fresnel lens with different defocus ratios depending on the region. This allows the surface lighting device to achieve a good appearance from two directions while improving the non-uniformity of brightness in each direction. For example, the surface lighting device can increase the dominance of light incident on the light distributing lens in the inclined direction during segmentation, thereby increasing brightness.

[0054] The plurality of light sources are arranged in a grid pattern, which makes it easy to support local dimming drive and allows the reflecting walls of the reflector arranged between the light sources to be formed regularly, thereby efficiently improving bright lines and dark lines.

[0055] Furthermore, the present invention is not limited to the above-described embodiments. Configurations in which the above-described components are appropriately combined are also included in the present invention. Furthermore, further effects and modifications can be easily derived by those skilled in the art. Therefore, the broader aspects of the present invention are not limited to the above-described embodiments, and various modifications are possible.

[0056] REFERENCE SIGNS LIST 1 Planar lighting device, 2 Bottom frame, 3 Substrate, 4 Light source, 5 Reflector, 51, 52 Reflecting wall, 52a, 52b Reflecting surface, 6 Condenser lens, 7 Light distribution lens, 71 Main surface, 72 Raised surface, 8 Reflective polarizing film

Claims

1. A surface lighting device comprising: a plurality of light sources; a reflector having a reflective surface surrounding the emission side of each of the plurality of light sources; a focusing lens arranged on the emission side of the reflector to focus light emitted from the plurality of light sources; and a light distribution lens arranged on the emission side of the focusing lens to tilt the distribution of light focused by the focusing lens in one direction, wherein the top of the reflector is arranged at a position offset from the center position of two adjacent light sources in the one direction.

2. The planar lighting device according to claim 1, wherein the top of the reflector is disposed at a position offset from the center position of two adjacent light sources in the tilt direction of the light distribution lens.

3. The planar lighting device according to claim 1, wherein the reflector has a pair of reflecting surfaces with different inclination angles.

4. The surface lighting device according to claim 1, wherein the angle of inclination of the first reflecting surface of the reflector, which is located on the side of the inclination direction of the light distributing lens, relative to the optical axis is smaller than the angle of inclination of the second reflecting surface, which is located on the opposite side of the first reflecting surface, relative to the optical axis.

5. The planar lighting device according to claim 1, wherein the condenser lens is an asymmetric Fresnel lens having different defocus ratios depending on the region.

6. The spread illuminating device according to claim 1, wherein the condensing lens has a small defocus ratio in a region on the side of the optical axis in the direction of inclination of the light distributing lens.

7. A surface lighting device comprising: a plurality of light sources; a reflector having an inclined reflecting surface surrounding the emission side of each of the plurality of light sources; a focusing lens arranged on the emission side of the reflector and focusing light emitted from the plurality of light sources; and a light distribution lens arranged on the emission side of the focusing lens and tilting the distribution of light focused by the focusing lens in one direction, wherein the focusing lens is an asymmetric Fresnel lens with a defocus ratio that varies depending on the region.

8. The surface lighting device according to claim 1 or 7, wherein the plurality of light sources are arranged in a grid pattern.

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