Lighting device

A lighting device includes a first light emitting part including a first light source part and a first optical part that includes a first reflecting part and a second reflecting part. A first direction from the first reflecting part to the second reflecting part crosses a second direction from the first light source part to the second reflecting part. A direction from the first light source part to the first reflecting part is along a first plane which includes the first direction and the second direction, and crosses the second direction. A distance between the first reflecting part and the first light source part is larger than a distance between the second reflecting part and the first light source part. A light distribution angle of a first-reflecting-part light in the first plane is larger than the light distribution angle of the second-reflecting-part light in the first plane.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No. 2019-144826 filed on Aug. 6, 2019, and Japanese Patent Application No. 2020-088636 filed on May 21, 2020, the disclosures of which are hereby incorporated by reference in their entireties.

BACKGROUND

The present disclosure relates to a lighting device.

For example, a lighting device is used to illuminate various objects such as a road, wall, or indoor space. Ina lighting device, there is a need to improve the brightness uniformity across an illuminated surface. See, for example, Japanese Patent Publication No. 2018-206704.

SUMMARY

The present disclosure may provide a lighting device capable of achieving an improved brightness uniformity across an illuminated surface.

According to one embodiment of the present disclosure, a lighting device includes a first light emitting part including a first optical part and a light source part. The first optical part includes a first reflecting part and a second reflecting part. A first direction extending from the first reflecting part to the second reflecting part crosses a second direction extending from the first light source part to the second reflecting part. A direction extending from the first light source part to the first reflecting part extends along a first plane which includes the first direction and the second direction, and crosses the second direction. A distance between the first reflecting part and the first light source part is larger than a distance between the second reflecting part and the first light source part. A light distribution angle of a first-reflecting-part light, that is a portion of a first outgoing light from the first light source part reflected by the first reflecting part, in the first plane is larger than a light distribution angle of a second-reflecting-part light, that is a portion of the first outgoing light reflected by the second reflecting part, in the first plane.

According to the embodiment of the present disclosure, a lighting device capable of achieving an improved brightness uniformity across an illuminated surface may be provided.

DETAILED DESCRIPTION

Certain embodiments of the present disclosure will be explained below with reference to the accompanying drawings.

The drawings are schematic or conceptual in nature, and as such, the relationship between the thickness and the width of each part, and the ratio of the size of one part to the size of another part are not necessarily the same as those in an actual structure. Moreover, depending on the drawing, even the same part might be shown in a different size or ratio.

In the description herein, similar elements to those described with reference to a previously described drawing will be denoted with the same reference numerals for which detailed description will be omitted as appropriate.

First Embodiment

FIG. 1is a schematic perspective view illustrating a lighting device according to a first embodiment.

FIG. 2is a schematic perspective view illustrating a portion of the lighting device according to the first embodiment.

FIG. 3is a schematic plan view illustrating a portion of the lighting device according to the first embodiment.

FIG. 4toFIG. 10are schematic sectional views each illustrating a portion of the lighting device according to the first embodiment.

As shown inFIG. 1, the lighting device110related to the first embodiment includes a first light emitting part81. The lighting device110can include a plurality of first light emitting parts81. The lighting device110can include a second light emitting part82. The second light emitting part82will be described later.

As shown inFIG. 1andFIG. 2, the first light emitting part81includes a first optical part10and a first light source part31. The first light source part31includes, for example, a light emitting diode (LED).

As shown inFIG. 3, the first light source part31can include a plurality of light sources, such as a first light source31a, a second light source31b, a third light source31cand the like. The first light source31a, the second light source31b, and the third light source31ceach includes an LED, for example. In this example, the first light source31ais located between the second light source31band the third light source31c. Light is output from each light source.

The first light source part31can be located at the central position of the first light source part31. For example, the position of the first light source part31can be substantially the central position of the first light source31a.

As shown inFIG. 2, the first optical part10includes a first reflecting part11and a second reflecting part12. As such, the first optical part10includes a plurality of reflecting parts. In this example, the first optical part10further includes a third reflecting part13and a fourth reflecting part14. At least one portion of the third reflecting part13is located between the first reflecting part11and the second reflecting part12. At least one portion of the fourth reflecting part14is located between the third reflecting part13and the second reflecting part12. The number of reflecting parts provided in the first optical part10can be appropriately determined.

As shown inFIG. 2, the first reflecting part11includes a first reflecting face11a, and the second reflecting part12includes a second reflecting face12b. In this example, the first reflecting part11includes a third reflecting face11cand a fourth reflecting face11d. For example, at least one portion of the first reflecting face11ais located between the third reflecting face11cand the fourth reflecting face11d. The second reflecting part12includes a fifth reflecting face12eand a sixth reflecting face12f. For example, at least one portion of the second reflecting face12bis located between the fifth reflecting face12eand the sixth reflecting face12f. The number of reflecting faces provided in each of the first reflecting part11and the second reflecting part12can be appropriately determined.

Practically, the first reflecting part11can be located at the central position of the first reflecting part11. For example, the first reflecting part11can substantially be located at the center11acof the first reflecting face11a(seeFIG. 4).

Practically, the second reflecting part12can be located at the central position of the second reflecting part12. For example, the position of the second reflecting part12can substantially be the center12bcof the second reflecting face12b(seeFIG. 4).

As shown inFIG. 2andFIG. 4, the direction from the first reflecting part11to the second reflecting part12is assumed as a first direction D1. As shown inFIG. 4, the direction from the center11acof the first reflecting face11ato the center12bcof the second reflecting face12bcorresponds to the first direction D1.

As shown inFIG. 2andFIG. 4, the direction from the first light source part31to the second reflecting part12is assumed as a second direction D2. The first direction D1crosses the second direction D2. For example, the second direction D2corresponds to the direction from the center of the first light source31aof the first light source part31to the center12bcof the second reflecting face12b.

As shown inFIG. 4, the direction Dz1from the first light source part31to the first reflecting part11is along a first plane which includes the first direction D1(i.e., the D1-D2plane) and the second direction D2. The direction Dz1crosses the second direction D2. In other words, using the position of the first light source part31as a reference, the direction to the second reflecting part12and the direction to the first reflecting part11are different from one another. The direction Dz1from the first light source part31to the first reflecting part11corresponds to the direction from the central position of the first light source part31to the central position of the first reflecting part11.

For example, the direction perpendicular to the first plane (the D1-D2plane) which includes the first direction D1and the second direction D2is assumed as a third direction D3.

As will be described later, the lighting device110illuminates, for example, a surface referred to as an illuminated surface. The light outgoing from the lighting device110is incident on the illuminated surface. The illuminated surface can be a road as one example. In this case, the lighting device is disposed on a lateral face crossing the illuminated surface (i.e., the surface of the road). The lateral face is a surface such as a sidewall. The road is illuminated by the lighting device110.

For example, the direction from the bottom to the top of the lateral face is assumed as a Y-axis direction (seeFIG. 2). The Y-axis direction is, for example, substantially perpendicular to the surface of the road. The direction from the bottom edge of the lateral face to the road is assumed as a Z-axis direction (seeFIG. 2). The Z-axis direction corresponds to the direction from the side of the road to the center of the road. At any focused position on the road, the direction in which the road extends is assumed as an X-axis direction (seeFIG. 2). The Y-axis direction, the Z-axis direction, and the X-axis direction orthogonal with one another.

For example, the third direction D3is along the X-axis direction. The first plane (the D1-D2plane) which includes the first direction D1and the second direction D2is, for example, perpendicular to the X-axis direction. For example, the first direction D1is oblique to the Z-axis direction. For example, the second direction D2is also oblique to the Z-axis direction.

For example, as shown inFIG. 3, the position of the first reflecting face11ain the third direction D3is located between the position of the third reflecting face11cin the third direction D3and the position of the fourth reflecting face11din the third direction D3.

FIG. 10corresponds to a cross section taken along the Z-X plane which includes the center of the first reflecting part11in the Y-axis direction. The first reflecting face11ain the third direction D3can practically be at the center11acof the first reflecting face11ain the third direction D3(seeFIG. 3andFIG. 10). The third reflecting face11cin the third direction D3can practically be at the center11ccof the third reflecting face11cin the third direction D3(seeFIG. 3andFIG. 10). The position of the fourth reflecting face11din the third direction D3can practically be at the center11dcof the fourth reflecting face11din the third direction D3(seeFIG. 3andFIG. 10).

For example, as shown inFIG. 3, the position of the second reflecting face12bin the third direction D3is between the position of the fifth reflecting face12ein the third direction D3and the position of the sixth reflecting face12fin the third direction D3.

FIG. 7corresponds to across section taken along the Z-X plane that includes the center of the second reflecting part12in the Y-axis direction. The position of the second reflecting face12bin the third direction D3can practically be at the center12bcof the second reflecting face12bin the third direction D3(seeFIG. 3andFIG. 7). The position of the fifth reflecting face12ein the third direction D3can practically be at the center12ecof the fifth reflecting face12ein the third direction D3(seeFIG. 3andFIG. 7). The position of the sixth reflecting face12fin the third direction D3can practically be at the center12fcof the sixth reflecting face12fin the third direction D3(seeFIG. 3andFIG. 7).

As shown inFIG. 3, the third reflecting part13is located, for example, between the first reflecting part11and the second reflecting part12. The third reflecting part13includes, for example, a seventh reflecting face13g, an eighth reflecting face13h, and a ninth reflecting face13i. For example, at least one portion of the seventh reflecting face13gis located between the first reflecting face11aand the second reflecting face12b. At least one portion of the eighth reflecting face13his located between the third reflecting face11cand the fifth reflecting face12e. At least one portion of the ninth reflecting face13iis located between the fourth reflecting face11dand the sixth reflecting face12f. The position of the seventh reflecting face13gin the third direction D3is between the position of the eighth reflecting face13hin the third direction D3and the position of the ninth reflecting face13iin the third direction D3. The number of reflecting faces provided in the third reflecting part13can be appropriately determined.

FIG. 9corresponds to a cross section taken along the Z-X plane which includes the center of the third reflecting part13in the Y-axis direction. The position of the seventh reflecting face13gin the third direction D3can practically be at the center13gcof the seventh reflecting face13gin the third direction D3(seeFIG. 9). The position of the eighth reflecting face13hin the third direction D3can practically be at the center13hcof the eighth reflecting face13hin the third direction D3(seeFIG. 9). The position of the ninth reflecting face13iin the third direction D3can practically be at the center13icof the ninth reflecting face13iin the third direction D3(seeFIG. 9).

As shown inFIG. 3, the fourth reflecting part14is located, for example, between the third reflecting part13and the second reflecting part12. The fourth reflecting part14includes, for example, a tenth reflecting face14j, an eleventh reflecting face14k, and a twelfth reflecting face14l. For example, at least one portion of the tenth reflecting face14jis located between the seventh reflecting face13gand the second reflecting face12b. At least one portion of the eleventh reflecting face14kis located between the eighth reflecting face13hand the fifth reflecting face12e. At least one portion of the twelfth reflecting face14lis located between the ninth reflecting face13iand the sixth reflecting face12f. The position of the tenth reflecting face14jin the third direction D3is between the position of the eleventh reflecting face14kin the third direction D3and the position of the twelfth reflecting face14lin the third direction D3. The number of reflecting faces provided in the fourth reflecting part14can be appropriately determined.

FIG. 8corresponds to a cross section taken along the Z-X plane which includes the center of the fourth reflecting part14in the Y-axis direction. The position of the tenth reflecting face14jin the third direction D3can practically be at the center14jcof the tenth reflecting face14jin the third direction D3(seeFIG. 8). The position of the eleventh reflecting face14kin the third direction D3can practically be at the center14kcof the eleventh reflecting face14kin the third direction D3(seeFIG. 8). The position of the twelfth reflecting face14lin the third direction D3can practically be at the center141cof the twelfth reflecting face14lin the third direction D3(seeFIG. 8).

The first to fourth reflecting parts11to14are, for example, discontinuous with one another. For example, multiple reflecting faces included in each of the first to fourth reflecting parts11to14are discontinuous with one another. For example, one or more steps are present between multiple reflecting faces included in each of the first to fourth reflecting parts11to14. For example, one or more steps are present between the first to fourth reflecting parts11to14.

As shown inFIG. 4toFIG. 10, for example, a first reflecting film18fcan be used as the first optical part10. In this example, the first reflecting film18fis disposed on the surface of the first member18M. For example, the first member18M is provided with protrusions and depressions. The first reflecting film18fis disposed on the surface having the protrusions and protrusions. The first member18M can include, for example, a resin, glass, or metal. Resins include, for example, polybutylene terephthalate (PBT). Using a resin can simplify processing. The first reflecting film18fincludes a metal film such as an aluminum film, for example. Light is reflected by the surface of the first reflecting film18f. For example, the first to fourth reflecting parts11to14include the first reflecting film18fdisposed on the surface of the first member18M. For example, the first to fourth reflecting parts11to14correspond to the surface of the first reflecting film18f. For example, the reflecting faces correspond to the surface of the first reflecting film18f.

The light outgoing from the first light source part31is incident on the multiple reflecting parts included in the first optical part10. The reflecting parts reflect the light outgoing from the first light emitting part81. The reflected light is incident on the illuminated surface, for example, a road.

The light outgoing from the first light source part31is incident on multiple reflecting faces. The reflecting faces reflect the light outgoing from the first light emitting part81. The reflected light is incident on the illuminated surface, for example, a road.

As shown inFIG. 4, the distance d1between the first reflecting part11and the first light source part31is larger than the distance d2between the second reflecting part12and the first light source part31. The distance d1, for example, corresponds to the distance between the center11acof the first reflecting face11aand the center of the first light source part31. The distance d2, for example, corresponds to the distance between the center12bcof the second reflecting face12band the center of the light source part31.

FIG. 11is a schematic plan view illustrating the reflection of light in the lighting device according to the first embodiment.

FIG. 12is a schematic sectional view illustrating the reflection of light in the lighting device according to the first embodiment.

FIG. 13is a schematic diagram illustrating light in the lighting device according to the first embodiment.

As shown inFIG. 4andFIG. 11, a portion of the first outgoing light31L from the first light source part31is reflected by the first reflecting part11, and then becomes the first-reflecting-part light11L. A portion of the first outgoing light31L from the first light source part31is reflected by the second reflecting part12, and then becomes the second-reflecting-part light12L.

As shown inFIG. 4andFIG. 11, the first-reflecting-part light11L includes, for example, first-reflecting-face light11aL which is the first outgoing light31L from the first light source part31reflected by the first reflecting face11a. The second-reflecting-part light12L includes, for example, second-reflecting-face light12bL which is the first outgoing light31L from the first light source part31reflected by the second reflecting face12b.

As shown inFIG. 12andFIG. 13, the light distribution angle DA1of the first-reflecting-part light11L in the first plane (the D1-D2plane) is larger than the light distribution angle DA2of the second-reflecting-part light12L in the first plane. The light distribution angle DA1corresponds, for example, to the light distribution angle of the first-reflecting-face light11aL in the first plane (the D1-D2plane). The light distribution angle DA2corresponds, for example, to the light distribution angle of the second-reflecting-face light12bL in the first plane (the D1-D2plane). Alight distribution angle corresponds to an angle range for one half of the highest intensity of light (full width at half maximum).

As shown inFIG. 4andFIG. 13, for example, the first reflecting part11has a first focal point11fin the first plane (the D1-D2plane). The distance from the first reflecting part11to the first focal point11fcorresponds to the first focal point distance f1(seeFIG. 13). As shown inFIG. 13, the first-reflecting-part light11L is incident on the illuminated surface91after advancing through the focal point11f.

On the other hand, the second reflecting part12has no focal point in the first plane (the D1-D2plane). Alternatively, in the case in which the second reflecting part12has a focal point in the first plane (the D-D2plane), the focal point distance of the second reflecting part12is larger than the first focal point distance f1.

As shown inFIG. 13, the first light emitting part81allows light (i.e., the first-reflecting-part light11L, the second-reflecting-part light12L, and the like) to be incident on the illuminated surface91from a side of the illuminated surface91. The first-reflecting-part light11L is incident on a first illuminated region R1of the illuminated surface91. The second-reflecting-part light12L is incident on a second illuminated region R2of the illuminated surface91. The distance between at least one portion of the first illuminated region R1and the first light emitting part81is smaller than the distance between the second illuminated region R2and the first light emitting part81.

The distance between the first illuminated region R1and the first light emitting part81is smaller than the distance between the second illuminated region R2and the first light emitting part81. The first-reflecting-part light11L is incident on the first illuminated region R1in the illuminated surface91. The second-reflecting-part light12L is incident on the second illuminated region R2in the illuminated surface91.

In this embodiment, the first reflecting part11is located farther from the first light source part31than the second reflecting part12is. The second reflecting part12is located closer to the first light source part31than the first reflecting part11is. The light distribution angle DA1of the first-reflecting-part light11L reflected by the first reflecting part11is larger than the light distribution angle DA2of the second-reflecting-part light12L reflected by the second reflecting part12. This can further improve the brightness uniformity in the illuminated surface91.

The first-reflecting-part light11L reflected by the first reflecting part11is incident on the first illuminated region R1that is closer to the first light source part31, and the second-reflecting-part light12L reflected by the second reflecting part12is incident on the second illuminated region R2in the illuminated surface91. At this time, by setting the relationship between the light distribution angles described above, the brightness of the illuminated regions can be brought closer between closer region to and farther region from the first light source part31. This can improve the brightness uniformity in the illuminated surface91.

For example, there is a lighting device as a first reference example that illuminates an illuminated surface91such as a road from the above. In this case, the angle of incidence of the light outgoing from the lighting device to the illuminated surface91is small. In other words, the light is incident on the illuminated surface91at an angle close to perpendicular to the surface. The light is incident on the illuminated surface91with a small angle of incidence. In the case of such a first reference example, there is relatively small variation in the distance between the illuminated surface and the lighting device. It is therefore relatively easy to improve the brightness uniformity in the illuminated surface91.

An automotive headlight, for example, can be cited as a second reference example that laterally illuminates an illuminated surface91such as a road. The angle of incidence of the light outgoing from the headlight to the illuminated surface91is relatively large. Such a second reference example is designed such that the light distribution angle of the light reflected by a reflecting part located farther from the light source is smaller than the light distribution angle of the light reflected by a reflecting part disposed closer to the light source. It was found that increasing the angle of incidence in such a second reference example made it difficult to improve the brightness uniformity in the illuminated surface91. The automotive headlight design concept may addresses the point of brightly illuminating distant objects, however, generally has a difficulty in providing uniform brightness across a large area from a far region to a close region.

In contrast, the embodiment of the present disclosure can achieve brightness uniformity in the illuminated surface91even when the first light emitting part81allows the light to be incident on the illuminated surface91from a side of the illuminated surface91with a broad range of angles of incidence. In the embodiment of the present disclosure, the depression angle of the light outgoing from the first light emitting part81is in a range of, for example, about 1 to about 40 degrees. In the case of the second reference example such as an automotive headlight, the depression angle is in a range of about 1 to about 10 degrees. As described above, in the case of the second reference example, brightness uniformity is poor even with depression angles is in a range of 1 to 10 degrees. In contrast, in the embodiment of the present disclosure, uniform brightness can be achieved over a wide range of depression angles such as from 1 to 40 degrees.

The light reflected by other reflecting parts (e.g., the third reflecting part13, the fourth reflecting part14, and the like) is incident on the area between the first illuminated region R1and the second illuminated region R2. A large area can be illuminated with uniform brightness.

As shown inFIG. 12, in the embodiment of the present disclosure, the depression angle of the first-reflecting-part light11L is larger than the depression angle of the second-reflecting-part light12L. For example, a first angle θ1formed by the optical axis11xof the first-reflecting-part light11L and the second direction D2is larger than a second angle62formed by the optical axis12xof the second-reflecting-part light12L and the second direction D2. When the first light emitting part81illuminates the illuminated surface91from a side of the illuminated surface91, this relationship of angles allows the first-reflecting-part light11L to be incident on a closer region in the illuminated surface91, and the second-reflecting-part light12L to be incident on a farther region in the illuminated surface91.

FIG. 14toFIG. 21are schematic diagrams illustrating light distribution angles in the lighting device according to the first embodiment.

InFIG. 14toFIG. 21, the horizontal axis represents light distribution angles LX (degrees) in the X-axis direction, and the vertical axis represents light distribution angles LY (degrees) in the Y-axis direction. A light distribution angle LX in the X-axis direction corresponds to a light distribution angle in the third direction D3perpendicular to the first plane (the D1-D2plane) which includes the first direction D1and the second direction D2. A light distribution angle LY in the Y-axis direction corresponds to a light distribution angle in the first plane.

As shown inFIG. 14, the light distribution angle LX11of the first-reflecting-part light11L in the X-axis direction (i.e., the third direction D3) is larger than the light distribution angle LX12described later. As previously explained, the light distribution angle LY11of the first-reflecting-part light11L in the Y-axis direction is larger than the light distribution angle LY12described later.

As shown inFIG. 17, the light distribution angle LX12of the second-reflecting-part light12L in the X-axis direction is smaller than the light distribution angle LX11. As previously explained, the light distribution angle LY12of the second-reflecting-part light12L in the Y-axis direction is smaller than the light distribution angle LY11.

As shown inFIG. 15, the third-reflecting-part light13L has a light distribution angle LX13in the X-axis direction (i.e., the third direction D3) and a light distribution angle LY13in the Y-axis direction. In one example, the light distribution angle LX13is positioned between the light distribution angle LX11and the light distribution angle LX12. In one example, the light distribution angle LY13is positioned between the light distribution angle LY11and the light distribution angle LY12.

As shown inFIG. 16, the fourth-reflecting-part light14L has a light distribution angle LX14in the X-axis direction (i.e., the third direction D3) and a light distribution angle LY14in the Y-axis direction. In one example, the light distribution angle LX14is positioned between the light distribution angle LX13and the light distribution angle LX12. In one example, the light distribution angle LY14is positioned between the light distribution angle LY13and the light distribution angle LY12.

The light distribution angle LX11and the light distribution angle LYl1correspond to the entire area of light distribution angles of the light beams reflected by the multiple reflecting faces included in the first reflecting part1. The light distribution angle LX12and the light distribution angle LY12correspond to the entire area of light distribution angles of the light reflected by the multiple reflecting faces included in the second reflecting part12. The light distribution angle LX13and the light distribution angle LY13correspond to the entire area of light distribution angles of the light reflected by the multiple reflecting faces included in the third reflecting part13. The light distribution angle LX14and the light distribution angle LY14correspond to the entire area of light distribution angles of the light reflected by the multiple reflecting faces included in the fourth reflecting part14.

FIG. 18illustrates the distribution angles of the first-reflecting-face light11aL reflected by the first reflecting face11a.FIG. 19illustrates the distribution angles of the seventh-reflecting-face light13gL reflected by the seventh reflecting face13g.FIG. 20illustrates the distribution angles of the tenth-reflecting-face light14jL reflected by the tenth reflecting face14j.FIG. 21illustrates the distribution angles of the second-reflecting-face light12bL reflected by the second reflecting face12b.

As shown inFIG. 18, the first-reflecting-face light11aL has a light distribution angle LX11ain the X-axis direction (i.e., the third direction D3) and a light distribution angle LY11ain the Y-axis direction. As shown inFIG. 19, the seventh-reflecting-face light13gL has a light distribution angle LX13gin the X-axis direction (i.e., the third direction D3) and a light distribution angle LY3gin the Y-axis direction. As shown inFIG. 20, the tenth-reflecting-face light14jL has a light distribution angle LX14jin the X-axis direction (i.e., the third direction D3) and a light distribution angle LY14jin the Y-axis direction. As shown inFIG. 21, the second-reflecting-face light12bL has a light distribution angle LX12bin the X-axis direction (i.e., the third direction D3) and a light distribution angle LY12bin the Y-axis direction.

For example, the light distribution angle LX11ais larger than the light distribution angle LX12b. The light distribution angle LX11acorresponds to the light distribution angle of the first-reflecting-face light11aL, which is a portion of the first outgoing light31L reflected by the first reflecting face11a, in the third direction D3. The light distribution angle LX12bcorresponds to the distribution angle of the second-reflecting-face light12bL, which is a portion of the first outgoing light31L reflected by the second reflecting face12b, in the third direction D3.

For example, the light distribution angle LY11ais larger than the light distribution angle LY12b. The light distribution angle LY11a, for example, corresponds to the light distribution angle of the first-reflecting-face light11aL in the first plane (the D1-D2plane). The light distribution angle LY12bcorresponds to the light distribution angle of the second-reflecting-face light12bL in the first plane.

In one example, the light distribution angle LX13gis positioned between the light distribution angle LX11aand the light distribution angle LX12b. In one example, the light distribution angle LY13gis positioned between the light distribution angle LY11aand the light distribution angle LY12b. In one example, the light distribution angle LX14jis positioned between the light distribution angle LX13gand the light distribution angle LX12b. In one example, the light distribution angle LY14jis positioned between the light distribution angle LY13gand the light distribution angle LY12b.

As shown inFIG. 10, the first reflecting part11has a protrusions shape. For example, the first reflecting face11ais protruded with reference to the third reflecting face11c. For example, the first reflecting face11ais protruded with reference to the fourth reflecting face11d. In this manner, the first reflecting part11has a protruding shape in at least one of the traveling directions of the first-reflecting-part light11L (in this example, the direction is along the Z-axis direction, seeFIG. 11). With such a shape, the first-reflecting-part light11L spreads widely. This can increase the light distribution angle of the first-reflecting-part light11L in the X-axis direction.

As shown inFIG. 7, the second reflecting part12has a depressed shape. For example, the second reflecting face12bis depressed with reference to the fifth reflecting face12e. For example, the second reflecting face12bis depressed with reference to the sixth reflecting face12f. In this manner, the second reflecting part12has a depressed shape in at least one of the traveling directions of the second-reflecting-part light12L (in this example, the direction is along the Z-axis direction, seeFIG. 11).

As shown inFIG. 9, in this example, the third reflecting part13has a depressed shape. For example, the third reflecting part13has a depressed shape in at least one of the traveling directions of the third-reflecting-part light13L. As shown inFIG. 8, in this example, the fourth reflecting part14has a depressed shape. For example, the fourth reflecting part14has a depressed shape in at least one of the traveling directions of the fourth-reflecting-part light14L.

As shown inFIG. 4, in a section cut in parallel with the first plane (the D1-D2plane), the first reflecting face11ahas a depressed shape. In a section cut in parallel with the first plane, the second reflecting face12bhas a depressed shape. In a section cut in parallel with the first plane, the seventh reflecting face13ghas a depressed shape. In a section cut in parallel with the first plane, the tenth reflecting face14jhas a depressed shape.

A second plane which includes the third direction D3is, for example, the X-Z plane. As shown inFIG. 10, in a section cut in parallel with the second plane, the first reflecting face11ahas a protruded shape. As shown inFIG. 7, in a section cut in parallel with the second plane, the second reflecting face12bhas a depressed shape or is substantially planar.

As shown inFIG. 5, in a section cut in parallel with the first plane (the D1-D2plane), the third reflecting face11chas a depressed shape. As shown inFIG. 6, in a section cut in parallel with the first plane, the fourth reflecting face11dhas a depressed shape.

As shown inFIG. 10, in a section cut in parallel with the second plane (the X-Z plane), the third reflecting face11chas a protrusions shape. In a section cut in parallel with the second plane, the fourth reflecting face11dhas a protrusions shape. Such a shape can increase the light distribution angle of the first-reflecting-part light11L reflected by the first reflecting part11.

As shown inFIG. 4, the first, second, third and fourth reflecting parts11,12,13and14respectively have first, second, third and fourth lengths H1, H2, H3and H4along the Y-axis direction. The first to fourth lengths H1to H4correspond to the heights. The first length H1is greater than the second length H2. For example, the third length H3is smaller than the first length H1, and smaller than the second length H2. For example, the fourth length H4is smaller than the first length H1, and smaller than the second length H2.

For example, changing the first to fourth lengths H1to H4can changes the areas of the first to fourth reflecting parts11to14. Increasing the first length H1can increase the sizes of the reflecting faces, thereby illuminating a wide region near the first light source part31. Increasing the second length H2to some extent can adequately increase the sizes of the reflecting faces, thereby illuminating a region farther from the first light source part31with required brightness. The intermediate parts such as the third reflecting part13and the fourth reflecting part14do not necessarily need large areas because they can receive the effect of the first-reflecting-part light11L from the first reflecting part11or the second-reflecting-part light12L from the second reflecting part12.

As previously explained, a plurality of first light emitting parts81can be provided. As shown inFIG. 1, in one example, the arrangement direction from one of the first light emitting parts81to another one of the first light emitting part81is along the third direction D3.

An example of a second light emitting part82will be explained below. As shown inFIG. 1, in the case of disposing a plurality of first light emitting parts81, for example, at least a portion of the second light emitting part82can be disposed between the first light emitting parts81.

FIG. 22toFIG. 24are schematic diagrams illustrating a portion of the lighting device according to the first embodiment of the present disclosure.

FIG. 22toFIG. 24each illustrate a second light emitting part82.FIG. 22is a perspective view.FIG. 23is a sectional view taken along line XXIII-XXIII inFIG. 22.FIG. 24is a plan view.

As shown inFIG. 22toFIG. 24, the second light emitting part82includes a second optical part20and a second light source part32. The second optical part20has a second-optical-part reflecting face21. The second-optical-part reflecting face21is, for example, a continuously curved surface. The second light source part32allows the second outgoing light32L to be incident on the second-optical-part reflecting face21.

The second light source part32includes, for example, an LED. The light from the LED is incident on the second-optical-part reflecting face21. The light reflected by the second-optical-part reflecting face21becomes the second-optical-part reflected light21L. The second-optical-part reflected light21L is incident on the illuminated surface91. The second-optical-part reflecting face21has a continuous depressed shape at least in one of the traveling directions of the second-optical-part reflected light21L.

As shown inFIG. 23, a second reflecting film28fcan be used as the second optical part20. In this example, the second reflecting film28fis disposed on the surface of the second member28M. For example, a depression is provided in the second member28M. The second reflecting film28fis disposed on the surface on which the depression is formed. The second member28M can contain, for example, a resin, glass, or metal. Examples of the second reflecting film28fincludes a metal film such as aluminum film. Light is reflected at the surface of the second reflecting film28f. The second-optical-part reflecting face21includes, for example, the second reflecting film28fdisposed on the surface of the second member28M.

As shown inFIG. 23, the second-optical-part reflected light21L spreads in the Y-Z plane. As shown inFIG. 24, the second-optical-part reflected light21L spreads in the X-Z plane. The second-optical-part reflected light21L also spreads in the X-axis direction while advancing along the Z-axis direction.

FIG. 25is a schematic diagram illustrating light in a lighting device according to the first embodiment of the present disclosure.

FIG. 25illustrates the second-optical-part reflected light21L outgoing from the second light emitting part82.FIG. 25illustrates the first illuminated region R1on which the first-reflecting-part light11L is incident, and the second illuminated region R2on which the second-reflecting-part light12L is incident. InFIG. 25, the position of the first light emitting part81is substantially the same as the position of the second light emitting part82. In order for the drawing to be easily understood, the first light emitting part81is omitted inFIG. 25.

As shown inFIG. 25, the lighting device110illuminates the illuminated surface91from one side of the illuminated surface91. The light outgoing from the first light emitting part81(e.g., the first-reflecting-part light11L) is incident on the first illuminated region R1of the illuminated surface91. In other words, the first light emitting part81illuminates the first illuminated region R1. The light outgoing from the second light emitting part82(e.g., the second-optical-part reflected light21L) is incident on a third illuminated region R3of the illuminated surface91. In other words, the second light emitting part82illuminates the third illuminated region R3. At least one portion of the third illuminated region R3is closer than the first illuminated region R1with reference to the first light emitting part81or the second light emitting part82. The distance between at least one portion of the third illuminated region R3and the second light emitting part82is smaller than the distance between the first illuminated region R1and the first light emitting part81. For example, the third illuminated region R3, the first illuminated region R1, and the second illuminated region R2are formed in that order of being the closest to the furthest from the lighting device110.

The reflecting parts (e.g., the first reflecting part11, the second reflecting part12, and the like) included in the first light emitting part81reflect light to allow the reflect light to be incident on the first illuminated region R1. The second-optical-part reflecting face21included in the second light emitting part82reflects light to allow the reflect light to be incident on the third illuminated region R3. Combination of the first light emitting part81and the second light emitting part82, a large area can be illuminated with uniform brightness.

The first reflecting part11is farther from a light source than the second reflecting part12is. For example, the first-reflecting-part light11L reflected by the first reflecting part11has a larger light distribution angle and a larger depression angle than those of the second-reflecting-part light12L described later. The first-reflecting-part light11L reflected by the first reflecting part11illuminates the first illuminated region R1located in the middle. The second-reflecting-part light12L reflected by the second reflecting part12has a smaller light distribution angle and a smaller depression angle than those of the first-reflecting-part light11L. The second-reflecting-part light12L reflected by the second-reflecting-part12illuminates the second illuminated region R2located further away. The second-optical-part reflected light21L reflected by the second-optical-part reflecting face21of the second light emitting part82illuminates the third illuminated region R3located closer to the second light emitting part82. For example, the brightness unevenness remaining in the light from the first light emitting part81is compensated for by the light from the second light emitting part82, thereby achieving uniform brightness across a large area.

FIG. 26is a schematic diagram illustrating the lighting devices according to the first embodiment in use.

As shown inFIG. 26, the illuminated surface91is a road surface. A sidewall92meeting the illuminated surface91is provided. The lighting devices110according to the embodiment are disposed, for example, on the sidewall92. The lighting devices110are disposed, for example, on the lateral face92fthat meets the illuminated surface91to illuminate the road from the side of the road. Accordingly, uniform brightness in the Z-axis direction may be achieved by one lighting device110.

As shown inFIG. 26, a plurality of lighting devices110are arranged along the X-axis direction. In the illuminated surface91, a portion of the light outgoing from one of the lighting devices110overlaps with the light outgoing from another one of the lighting devices110. The brightness in the X-axis direction can be made uniform by the plurality of lighting devices110.

Second Embodiment

FIG. 27is a schematic sectional view illustrating a portion of a lighting device according to a second embodiment of the present disclosure.

FIG. 27illustrates a first light emitting part81A in a lighting device120according to the second embodiment.FIG. 27is a cross section corresponding to the cross section shown inFIG. 4.

As shown inFIG. 27, the first light emitting part81A also includes a first optical part10and a first light source part31. The first optical part10includes a first member18M and a first reflecting film18f. The light outgoing from the first light source part31transmits through the first member18M before being incident on the first reflecting film18f. The light reflected by the first reflecting film18fis incident on the illuminated surface91. The first optical part10in this case also includes a plurality of reflecting parts, such as the first reflecting part11, the second reflecting part12, and the like. The first reflecting film18ffunctions as multiple reflecting parts.

As in the case of the first light emitting part81A in the lighting device120, the first optical part10can be of a back-face reflection type. For the reflecting parts in the second embodiment, the reflecting parts configured as explained in relation to the first embodiment can be applied. The lighting device provided according to the second embodiment can also exhibit an improved brightness uniformity in the illuminated surface.

Third Embodiment

FIG. 28is a schematic sectional view illustrating a portion of a lighting device according to a third embodiment of the present disclosure.

FIG. 28illustrates a second light emitting part82A in a lighting device130according to the third embodiment.FIG. 28illustrates a cross section corresponding to the cross section shown inFIG. 23.

As shown inFIG. 28, the second lighting part82A also includes a second optical part20and a second light source part32. The second optical part20includes a second member28M and a second reflecting film28f. The light outgoing from the second light source part32transmits through the second member28M before being incident on the second reflecting film28f. The light reflected by the second reflecting film28fis incident on the illuminated surface91. The second optical part20in this case also has a second-optical-part reflecting face21. The second reflecting film28ffunctions as the second-optical-part reflecting face21.

As in the case of the second optical part82A in the lighting device130, the second optical part20can be of a back-face reflection type. For the second-optical-part reflecting face21in the third embodiment, the second-optical-part reflecting face21configured as explained in relation to the first embodiment can be applied. The lighting device provided according to the third embodiment can also exhibit an improved brightness uniformity in the illuminated surface.

The first light emitting part81A explained in relation to the second embodiment and the second light emitting part82A explained in relation to the third embodiment can be combined.

Another example of the usage of a lighting device according to an embodiment will be explained below. In the example below, alighting device110is used as the lighting device according to the embodiment.

FIG. 29is a schematic diagram of the lighting device according to the embodiment in use.

As shown inFIG. 29, any of the lighting devices according to the first to third embodiments can illuminate a building95. The illuminated surface91is, for example, a wall face95S of the building95. The light outgoing from the lighting device110is incident on the wall face95S, achieving a substantially uniform brightness at least in a portion of the wall face95S, for example, in the illuminated region91E. The illuminated region91E corresponds to the “effective illuminated region”. As shown inFIG. 29, the lighting device110can be disposed at a distance or far from the ground96.

The height of the building95corresponds to the Z axis direction. The left/right direction of the wall face95S corresponds to the X axis direction. The direction perpendicular to the wall face95S corresponds to the Y axis direction. The length of the illuminated region91E along the Z axis direction is denoted as length Dh3(i.e., height). The length of the illuminated region91E along the X axis direction is denoted as length Dx3(i.e., left/right width). As shown inFIG. 29, the angle formed by the line extending in the Z axis direction from the projected position of the emission part110L on the illuminated surface91(i.e., wall face95S) in the Y axis direction and the line extending from the projected position of the emission part110L on the illuminated surface91(i.e., wall face95S) in the Y axis direction to one end91Le of the lower edge91L of the illuminated region91is denoted as angle ϕ3.

Examples of simulated characteristics of the lighting device110will be explained below.

FIG. 30is a schematic lateral face view illustrating the lighting device according to the embodiment in use.

As shown inFIG. 30, the distance between the emission part110L of the lighting device110and the illuminated surface91(i.e., wall face95S) along the Y axis direction is denoted as a distance Dy1. The distance Dy1corresponds to the distance to the emission part110L from the wall face95S. The distance between the lower edge of the illuminated region91E and the emission part110L along the Z axis direction is denoted as a length Dh1. The distance between the upper edge of the illuminated region91E and the emission part110L along the Z axis direction is denoted as a length Dh2. The sum of the length Dh1and the length Dh3corresponds to the length Dh2. As shown inFIG. 30, in the Y-Z plane passing the emission part110L, the angle formed by the illuminated surface91(wall face95S) and the direction, which connects the emission part110L and the lower edge91L of the illuminated region91E, is denoted as angle ϕ1. In the Y-Z plane passing the emission part110L, the angle formed by the illuminated surface91(i.e., wall face95S) and the direction, which connects the emission part110L and the upper edge91U of the illuminated region91E, is denoted as angle ϕ2.

FIG. 31is a table showing the characteristics of the lighting device according to the embodiment.

FIG. 31shows examples of simulation results of the illuminated region91E (the “effective illuminated region” where a substantially uniform brightness can be achieved) when the distance Dy1(i.e., distance from the wall face95S to the emission part110L) is changed. In this example, the range in which one half of the peak illuminance in the illuminated region91E can be achieved constitutes the outer boundary of the illuminated region91E. In other words, the illuminance at the edges of the illuminated region91E in the height direction thereof referred to as the length Dh3(i.e., height), and the edges of the illuminated region91E in the left/right direction thereof referred to as the length Dx3(i.e., left/right width), is one half of the peak illuminance. The illuminance within the illuminated region91E is substantially uniform, and the illuminance outside of the illuminated region91E is nonuniform. In practice, the range in which one half of the peak illuminance in the illuminated region91E is substantially achieved may be considered as the outer boundary of the illuminated region91E.

FIG. 31also shows average illuminance AvIL and distance coefficient CD. Average illuminance AvIL is the average illuminance in the illuminated region91E. Distance coefficient CD is a ratio of a distance Dy1when the distance Dy1of 1.0975 m is 1.

As shown inFIG. 31, as the distance Dy1increases, the lengths Dh1, Dh2, Dh3, and Dx3increase. In other words, as the distance Dy1increases, the size of the illuminated region91E both in the height direction and the left/right direction increases. On the other hand, as the distance Dy1increases, the average illuminance AvIL decreases.

FIG. 32andFIG. 33are schematic diagrams showing the characteristics of the lighting device according to the embodiment.

InFIG. 32, illuminance IL in the X-Z plane is shown. Positions pX in the X axis direction and positions in the Z axis direction pZ is defined by using the position of the emission part110L as a reference. The diagrams inFIG. 33represent enlarged portions of those shown inFIG. 32. As shown inFIG. 32andFIG. 33, the illuminance IL is substantially symmetrical at positions pX on the left and right sides in the X axis direction. The illuminance IL declines as the positions pZ is numbered with a greater numeral along the Z axis direction. As shown inFIG. 32andFIG. 33, the illuminated region91E with substantially uniform illuminance is substantially rectangular in shape.

When the distance Dy1changes, the size of the illuminated region91E changes because the illuminated regions91E shown in bothFIG. 32andFIG. 33are correlated.

In one example, when the distance Dy1is 1.75 m, the length Dh1is 2.79 m, the length Dh2is 22.2 m, and the length Dh3is 19.4 m. In this case, the average illuminance AvIL in the illuminated region91E is 11.02 lx.

The simulation result examples described above are also applicable in the case in which the illuminated surface91is a road surface. In this case, the distance Dy1corresponds to the distance (i.e., height) from the road surface to the emission part110L.

As shown inFIG. 1andFIG. 2, the first light emitting part81includes a first light reflector10(also referred to herein as the optical part) and a first light source part31. The first light source part31includes, for example, alight emitting diode (LED).

As shown inFIG. 3, the first light source part31can include a plurality of light sources, such as a first light source31a, a second light source31b, a third light source31cand the like. The first light source31a, the second light source31b, and the third light source31ceach includes an LED, for example. In this example, the first light source31ais located between the second light source31band the third light source31c. Light is output from each light source. The light source is positioned laterally adjacent to the light reflector10.

The first light source part31can be located at the central position of the first light source part31. For example, the position of the first light source part31can be substantially the central position of the first light source31a.

As shown inFIG. 2, the first light reflector10includes multiple light reflective faces (also referred to herein as light reflecting parts) arranged in an array in an adjacent or non-adjacent manner. The array is an m by n array, where n is an integer with a value greater than one, and m is an integer with a value greater than one. The first light reflector10is shown with a three by four array of light reflective faces, though in some implementations the light reflector has more or less reflective faces in the array. The first light reflector10includes a first row of light reflecting faces11(also referred to herein as a first reflecting part) and a second row of light reflecting faces12(also referred to herein as a second reflecting part). As such, the first light reflector10includes a plurality of light reflecting faces.

In this example, the first light reflector10further includes a third row of light reflecting faces13and a fourth row of light reflecting faces14. At least one portion of the third row of light reflecting faces13is located between the first row of light reflecting faces11and the second row of light reflecting faces12. At least one portion of the fourth row of light reflecting faces14is located between the third row of light reflecting faces and the second row of light reflecting faces12. The number of rows of reflecting faces provided in the first optical part10can be appropriately determined.

As shown inFIG. 2, the first row of light reflecting faces11includes a first reflecting face11a, and the second row of light reflecting faces12includes a second reflecting face12b. In this example, the first row of light reflecting faces11includes a third reflecting face11cand a fourth reflecting face11d. For example, at least one portion of the first reflecting face11ais located between the third reflecting face11cand the fourth reflecting face11d. The second row of light reflecting faces12includes a fifth reflecting face12eand a sixth reflecting face12f. For example, at least one portion of the second reflecting face12bis located between the fifth reflecting face12eand the sixth reflecting face12f. The number of reflecting faces provided in each of the first row of light reflecting faces11and the second row of light reflecting faces12can be appropriately determined.

The light reflective faces are positioned in an optical path of the light source31. The first row of light reflecting faces11reflects light from the light source at a first light distribution angle. The second row of light reflecting faces12reflects light from the light source31at a second light distribution angle. Though the light distribution varies depending on the orientation of the light reflecting faces, the second light distribution angle of light reflected from a center of the second row of light reflecting faces12is greater than the first light distribution angle of light reflected from a center of the second row of light reflecting faces11. The relationship between the light distribution angles of the light reflecting faces will be described in greater detail below.

Practically, the first row of light reflecting faces11can be considered to be located at the central position of the first row of light reflecting faces11. For example, the first row of light reflecting faces11can substantially be located at the center11acof the first reflecting face11a(seeFIG. 4).

Practically, the second row of light reflecting faces12can be considered to be located at the central position of the second row of light reflecting faces12. For example, the position of the second row of light reflecting faces12can substantially be the center12bcof the second reflecting face12b(seeFIG. 4).

As shown inFIG. 2andFIG. 4, the direction from the first row of light reflecting faces11to the second row of light reflecting faces12is assumed as a first direction D1. As shown inFIG. 4, the direction from the center11acof the first reflecting face11ato the center12bcof the second reflecting face12bcorresponds to the first direction D1.

As shown inFIG. 2andFIG. 4, the direction from the first light source part31to the second row of light reflecting faces12is assumed as a second direction D2. The first direction D1intersects with the second direction D2. For example, the second direction D2corresponds to the direction from the center of the first light source31aof the first light source part31to the center12bcof the second reflecting face12b.

As shown inFIG. 4, the direction Dz1from the first light source part31to the first row of light reflecting faces11is along a first plane which includes the first direction D1(i.e., the D1-D2plane) and the second direction D2. The direction Dz1intersects with the second direction D2. In other words, using the position of the first light source part31as a reference, the direction to the second row of light reflecting faces12and the direction to the first row of light reflecting faces11are different from one another. The direction Dz1from the first light source part31to the first row of light reflecting faces11corresponds to the direction from the central position of the first light source part31to the central position of the first row of light reflecting faces11.

FIG. 10corresponds to a cross section taken along the Z-X plane which includes the center of the first row of light reflecting faces11in the Y-axis direction. The first reflecting face11ain the third direction D3can practically be at the center11acof the first reflecting face11ain the third direction D3(seeFIG. 3andFIG. 10). The third reflecting face11cin the third direction D3can practically be at the center11ccof the third reflecting face11cin the third direction D3(seeFIG. 3andFIG. 10). The position of the fourth reflecting face11din the third direction D3can practically be at the center11dcof the fourth reflecting face11din the third direction D3(seeFIG. 3andFIG. 10).

FIG. 7corresponds to a cross section taken along the Z-X plane that includes the center of the second row of light reflecting faces12in the Y-axis direction. The position of the second reflecting face12bin the third direction D3can practically be at the center12bcof the second reflecting face12bin the third direction D3(seeFIG. 3andFIG. 7). The position of the fifth reflecting face12ein the third direction D3can practically be at the center12ecof the fifth reflecting face12ein the third direction D3(seeFIG. 3andFIG. 7). The position of the sixth reflecting face12fin the third direction D3can practically be at the center12fcof the sixth reflecting face12fin the third direction D3(seeFIG. 3andFIG. 7).

As shown inFIG. 3, the third row of light reflecting faces13is located, for example, between the first row of light reflecting faces11and the second row of light reflecting faces12. The third row of light reflecting faces13includes, for example, a seventh reflecting face13g, an eighth reflecting face13h, and a ninth reflecting face13i. For example, at least one portion of the seventh reflecting face13gis located between the first reflecting face11aand the second reflecting face12b. At least one portion of the eighth reflecting face13his located between the third reflecting face11cand the fifth reflecting face12e. At least one portion of the ninth reflecting face13iis located between the fourth reflecting face11dand the sixth reflecting face12f. The position of the seventh reflecting face13gin the third direction D3is between the position of the eighth reflecting face13hin the third direction D3and the position of the ninth reflecting face13iin the third direction D3. The number of reflecting faces provided in the third row of light reflecting faces13can be appropriately determined.

FIG. 9corresponds to across section taken along the Z-X plane which includes the center of the third row of light reflecting faces13in the Y-axis direction. The position of the seventh reflecting face13gin the third direction D3can practically be at the center13gcof the seventh reflecting face13gin the third direction D3(seeFIG. 9). The position of the eighth reflecting face13hin the third direction D3can practically be at the center13hcof the eighth reflecting face13hin the third direction D3(seeFIG. 9). The position of the ninth reflecting face13iin the third direction D3can practically be at the center31cof the ninth reflecting face13iin the third direction D3(seeFIG. 9).

As shown inFIG. 3, the fourth row of light reflecting faces14is located, for example, between the third row of light reflecting faces13and the second row of light reflecting faces12. The fourth row of light reflecting faces14includes, for example, a tenth reflecting face14j, an eleventh reflecting face14k, and a twelfth reflecting face14l. For example, at least one portion of the tenth reflecting face14jis located between the seventh reflecting face13gand the second reflecting face12b. At least one portion of the eleventh reflecting face14kis located between the eighth reflecting face13hand the fifth reflecting face12e. At least one portion of the twelfth reflecting face14lis located between the ninth reflecting face13iand the sixth reflecting face12f. The position of the tenth reflecting face14jin the third direction D3is between the position of the eleventh reflecting face14kin the third direction D3and the position of the twelfth reflecting face14lin the third direction D3. The number of reflecting faces provided in the fourth row of light reflecting faces14can be appropriately determined.

FIG. 8corresponds to a cross section taken along the Z-X plane which includes the center of the fourth row of light reflecting faces14in the Y-axis direction. The position of the tenth reflecting face14jin the third direction D3can practically be at the center14jcof the tenth reflecting face14jin the third direction D3(seeFIG. 8). The position of the eleventh reflecting face14kin the third direction D3can practically be at the center14kcof the eleventh reflecting face14kin the third direction D3(seeFIG. 8). The position of the twelfth reflecting face14lin the third direction D3can practically be at the center141cof the twelfth reflecting face14lin the third direction D3(seeFIG. 8).

The first to fourth rows of light reflecting faces11to14are, for example, discontinuous with one another. For example, multiple reflecting faces included in each of the first to fourth rows of light reflecting faces11to14are discontinuous with one another. For example, one or more steps are present between multiple reflecting faces included in each of the first to fourth rows of light reflecting faces11to14. For example, one or more steps are present between the first to fourth rows of light reflecting faces11to14.

As shown inFIG. 4toFIG. 10, for example, a first reflecting film18fcan be used as the first optical part10. In this example, the first reflecting film18fis disposed on the surface of the first member18M. For example, the first member18M is provided with protrusions and depressions. The first reflecting film18fis disposed on the surface having the protrusions and protrusions. The first member18M can include, for example, a resin, glass, or metal. Resins include, for example, polybutylene terephthalate (PBT). Using a resin can simplify processing. The first reflecting film18fincludes a metal film such as an aluminum film, for example. Light is reflected by the surface of the first reflecting film18f. For example, the first to fourth rows of light reflecting faces11to14include the first reflecting film18fdisposed on the surface of the first member18M. For example, the first to fourth rows of light rows of light reflecting faces11to14correspond to the surface of the first reflecting film18f. For example, the reflecting faces correspond to the surface of the first reflecting film18f.

The light reflective faces of the light reflectors are positioned in an optical path of the light source31. The light outgoing from the first light source part31is incident on the multiple reflecting parts included in the first optical part10. The reflecting parts reflect the light outgoing from the first light emitting part81. The reflected light is incident on the illuminated surface, for example, a road.

The light outgoing from the first light source part31is incident on multiple reflecting faces. The reflecting faces reflect the light outgoing from the first light emitting part81. The reflected light is incident on the illuminated surface, for example, a road.

As shown inFIG. 4, the distance d between the first row of light reflecting faces11and the first light source part31is larger than the distance d2between the second row of light reflecting faces12and the first light source part31. The distance d1, for example, corresponds to the distance between the center11acof the first reflecting face11aand the center of the first light source part31. The distance d2, for example, corresponds to the distance between the center12bcof the second reflecting face12band the center of the light source part31.

FIG. 11is a schematic plan view illustrating the reflection of light in the lighting device according to the first embodiment.

FIG. 12is a schematic sectional view illustrating the reflection of light in the lighting device according to the first embodiment.

FIG. 13is a schematic diagram illustrating light in the lighting device according to the first embodiment.

As shown inFIG. 4andFIG. 11, a portion of the first outgoing light31L from the first light source part31is reflected by the first row of light reflecting faces11, and then becomes the first-reflecting-part light11L. A portion of the first outgoing light31L from the first light source part31is reflected by the second row of light reflecting faces12, and then becomes the second-reflecting-part light12L.

As shown inFIG. 4andFIG. 13, for example, the first row of light reflecting faces11has a first focal point11fin the first plane (the D1-D2plane). The distance from the first row of light reflecting faces11to the first focal point11fcorresponds to the first focal point distance f1(seeFIG. 13). As shown inFIG. 13, the first-reflecting-part light11L is incident on the illuminated surface91after advancing through the focal point11f.

On the other hand, the second row of light reflecting faces12has no focal point in the first plane (the D1-D2plane). Alternatively, in the case in which the second row of light reflecting faces12has a focal point in the first plane (the D1-D2plane), the focal point distance of the second row of light reflecting faces12is larger than the first focal point distance f1.

As shown inFIG. 13, the first light emitting part81allows light (i.e., the first-reflecting-part light11L, the second-reflecting-part light12L, and the like) to be incident on the illuminated surface91from a side of the illuminated surface91. The first-reflecting-part light11L is incident on a first illuminated region R1of the illuminated surface91. The second-reflecting-part light12L is incident on a second illuminated region R2of the illuminated surface91. The distance between at least one portion of the first illuminated region R1and the first light emitting part81is smaller than the distance between the second illuminated region R2and the first light emitting part81.

The distance between the first illuminated region R1and the first light emitting part81is smaller than the distance between the second illuminated region R2and the first light emitting part81. The first-reflecting-part light11L is incident on the first illuminated region R1in the illuminated surface91. The second-reflecting-part light12L is incident on the second illuminated region R2in the illuminated surface91.

In this embodiment, the first row of light reflecting faces11is located farther from the first light source part31than the second row of light reflecting faces12is. The second row of light reflecting faces12is located closer to the first light source part31than the first row of light reflecting faces11is. The light distribution angle DA1of the first-reflecting-part light11L reflected by the first row of light reflecting faces11is larger than the light distribution angle DA2of the second-reflecting-part light12L reflected by the second row of light reflecting faces12. This can further improve the brightness uniformity in the illuminated surface91.

The first-reflecting-part light11L reflected by the first row of light reflecting faces11is incident on the first illuminated region R1that is closer to the first light source part31, and the second-reflecting-part light12L reflected by the second row of light reflecting faces12is incident on the second illuminated region R2in the illuminated surface91. At this time, by setting the relationship between the light distribution angles described above, the brightness of the illuminated regions can be brought closer between closer region to and farther region from the first light source part31. This can improve the brightness uniformity in the illuminated surface91.

The embodiments can include following configurations:

at least one light reflector comprising a plurality of light reflective faces each adjacently arranged in an n by m array, n having an integer value greater than 1 and m having an integer value greater than 1; and

a light source positioned laterally adjacent to the at least one light reflector at a first distance from a center of a first row of the n by m array and a second distance from a center of a second row of the n by m array, the first distance being less than the second distance,

whereineach of the plurality of light reflective faces are oriented in an optical path of the light source,the first row comprising light reflective faces arranged to reflect light from the light source at a first light distribution angle,the second row comprising light reflective faces arranged to reflect light from the light source at a second light distribution angle, andthe first light distribution angle is greater than the second light distribution angle.

(Configuration 2) The lighting device of Configuration 1, wherein

the first light distribution angle is measured in a first plane comprising a first vector from the center of the first row to a center of the light source and a second vector from the center of the first row to the center of the second row, and

the second light distribution angle is measured in a second plane comprising a third vector from a center of the second row to the center of the light source and a fourth vector from the center of the second row to the center of the first row.

(Configuration 3) The lighting device of Configuration 2, wherein

the light from the light source reflected by the first row has a first focal length measured from the center of the first row in the first plane,

the light from the light source reflected by the second row has a second focal length measured from the center of the second row in the second plane, and

the first focal length is smaller than the second focal length.

(Configuration 4) The lighting device of Configuration 1, wherein each of the plurality of reflective light faces has a convex shape.

(Configuration 5) The lighting device of Configuration 1, wherein each n row of the n by m array has a concave shape or a convex shape.

(Configuration 6). The lighting device of Configuration 4, wherein at least one n row of the n by m array has a concave shape and at least another n row of the n by m array has a convex shape.

(Configuration 7) The lighting device of Configuration 1, where at least one n row of the n by m array has a radius of curvature different than a radius of curvature of the first row.

(Configuration 8) The lighting device of Configuration 6, wherein the second row has a radius of curvature greater than the radius of curvature of the second row.

(Configuration 9) The lighting device of Configuration 1, further comprising a reflecting film disposed on each of the plurality of light reflective faces.

(Configuration 10). The lighting device of Configuration 1, wherein each n row of the n by m array has a topographical profile that is different from a topographical profile of an adjacent n row of the n by m array.

According to any of the embodiments of the present disclosure explained, a lighting device with improved brightness uniformity in the illuminated surface can be provided.

In the description herein, “perpendicular” and “parallel” encompass not only being strictly perpendicular and strictly parallel, but also those including manufacturing tolerances, for example, and thus can be substantially perpendicular and substantially parallel.

Certain embodiments of the present disclosure have been explained above with reference to specific examples. The present invention, however, is not limited to these specific examples. For example, any specific configuration such as an optical part, reflecting part, reflecting face, light source part, or light source included in a lighting device is encompassed by the scope of the present invention so long as it is suitably selected from those available in the public domain by a person having ordinary skill in the art to similarly implement the present invention and achieve similar effects.

Moreover, one combining two or more elements in the specific examples to the technical extent possible also falls within the scope of the present invention so long as it encompasses the subject matter of the present invention.

All other lighting devices implementable by a person having ordinary skill in the art by means of a design change based on the lighting devices described as the embodiments of the present invention above also fall within the scope of the present invention so long as they encompass the subject matter of the present invention.

In addition, a person having ordinary skill in the art would be able to make various modifications and alterations within the scope of the technical ideas of the present invention, and such modifications and alterations are also understood to fall within the scope of the present invention.