Lighting device and lighting system

Abstract

A lighting device (1) is provided with: a light source (2) that emits emission light; a first lens (31) that receives the emission light and emits first light (L2); and a second lens (32) that receives the first light (L2) and emits second light (L3). The second lens (32) emits the second light (L3) so that said light is inclined with respect to an irradiation surface (4). The irradiation range (S2) of the second light (L3) is wider than the irradiation range (S1) of parallel light (L1).

Description

Lighting device and lighting system

[0001] The present disclosure relates to lighting devices and lighting systems.

[0002] 2. Description of the Related Art Line illumination units that illuminate a linear area with a desired illuminance are known (see, for example, Patent Document 1).

[0003] Japanese Patent Application Publication No. 5-299701

[0004] Incidentally, lighting devices that light up the exterior walls of buildings are known. In such lighting devices, light sources such as LEDs are embedded in the exterior walls of the building or arranged along the exterior walls to light up a predetermined area of ​​the exterior walls of the building. However, in such a configuration, the light sources must be arranged near the area to be lit up (the illumination range), which narrows the illumination range of the light sources. This requires the arrangement of a large number of light sources on the exterior walls of the building, which poses problems in terms of maintenance and cost of the lighting devices.

[0005] Therefore, an object of the present disclosure is to provide an illumination device and an illumination system that can reduce the number of light sources.

[0006] In order to achieve the above object, an embodiment of the present disclosure includes a light source that emits output light, a first lens that receives the output light and emits a first light, and a second lens that receives the first light and emits a second light, wherein the second lens emits the second light at an angle relative to an irradiation surface, and the second light has a wider irradiation range than the output light.

[0007] According to the present disclosure, the number of light sources can be reduced.

[0008] 10 is a side cross-sectional view of the illumination device according to the first embodiment. A simulation result of the irradiation range of the second light according to the first embodiment. A side cross-sectional view of the illumination device according to the second embodiment. A side cross-sectional view of the illumination device according to the third embodiment. A diagram showing an illumination device according to the fourth embodiment. A diagram showing an illumination device according to a modified example of the fourth embodiment. A diagram showing an illumination device according to the fifth embodiment. A diagram showing an illumination device according to a modified example of the fifth embodiment. A side cross-sectional view of an illumination device according to the sixth embodiment. A perspective view of an optical element according to the sixth embodiment. A simulation result of the irradiation range of the second light according to the sixth embodiment. A diagram showing the irradiation range of the second light according to a modified example of the sixth embodiment. A side cross-sectional view of the illumination device according to the seventh embodiment. A side cross-sectional view of the illumination device according to the eighth embodiment. A perspective view of a slit according to the eighth embodiment. A diagram showing an illumination device according to the ninth embodiment. A plan view showing an example of the arrangement of an illumination system. A plan view showing an example of the arrangement of an illumination system. A plan view showing an example of the arrangement of an illumination system.

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the present invention, its applications, or its uses. In the following description, the same parts will be designated by the same reference numerals, and detailed description will be omitted as appropriate.

[0010] (First embodiment) Fig. 1 is a side cross-sectional view of an illumination device according to a first embodiment. As shown in Fig. 1, the illumination device 1 is used to light up an illumination surface 4, which may be, for example, a wall surface of a building or a road surface. As shown in Fig. 1, the illumination device 1 is installed so that the optical axis of parallel light L1 emitted by the light source 2 is inclined with respect to the illumination surface 4. Therefore, illumination light (second light, which will be described later) from the illumination device 1 is emitted so as to be inclined with respect to the illumination surface 4.

[0011] In the following description, in Fig. 1, the depth direction of the drawing is referred to as the X direction, the vertical direction of the drawing as the Y direction, and the horizontal direction of the drawing as the Z direction. Also, in Fig. 1, the optical axis direction of the parallel light L1 is referred to as the z direction, the direction perpendicular to the z direction as the x direction, and the direction perpendicular to the z direction and the x direction as the y direction. It is assumed that the x direction and the X direction are the same. It is also assumed that the irradiation surface 4 extends in the X direction and the Z direction.

[0012] As shown in FIG. 1 , the lighting device 1 includes a light source 2 and a magnifying mechanism 3 .

[0013] The light source 2 is a parallel light source that emits parallel light L1 (emitted light). For example, the light source 2 is a laser light source configured with an LED or the like. The light source 2 may be a white laser light source or a monochromatic laser light source such as red or blue.

[0014] The magnifying mechanism 3 expands the irradiation range of the parallel light L1 (L11 to L13) received from the light source 2. Specifically, the magnifying mechanism 3 includes a first lens 31 and a second lens 32. The first lens 31 and the second lens 32 are made of quartz, optical glass, transparent resin, or the like. The first lens 31 and the second lens 32 are arranged so that their centers coincide with the z direction (the traveling direction of the parallel light L12). In other words, the first lens 31 and the second lens 32 are arranged so that their centers coincide with the optical axis direction of the parallel light L1 at the center.

[0015] The first lens 31 receives the parallel light L1 from the light source 2 and emits the first light L2 (L21 to L23). In this embodiment, the first lens 31 is a convex lens.

[0016] The second lens 32 receives the first light L2 from the first lens 31 and emits the second light L3 (L31 to L33). In this embodiment, the second lens 32 is a convex lens.

[0017] 1, the parallel light L1 emitted from the light source 2 has a certain irradiation range S1 in the x and y directions. The parallel light L11 is the light at the top of the parallel light L1 in the y direction on the drawing, the parallel light L12 is the light at the center of the parallel light L1 in the y direction on the drawing, and the parallel light L13 is the light at the bottom of the parallel light L1 in the y direction on the drawing.

[0018] When the parallel light L11 enters the first lens 31, it is refracted downward in the y direction in the drawing and is emitted as first light L21. Then, when the first light L21 enters the lower part of the second lens 32 in the y direction in the drawing, it is refracted in the y direction and is emitted as second light L31. Thereafter, the second light L31 is irradiated to the left side of the irradiation surface 4 in the Z direction in the drawing.

[0019] When the parallel light L12 enters the first lens 31, it passes through the first lens 31 and is emitted as first light L22. When the first light L22 enters the center of the second lens 32 in the y direction in the drawing, it passes through the second lens 32 and is emitted as second light L32. Thereafter, the second light L32 is irradiated onto the center of the irradiation surface 4 in the Z direction in the drawing.

[0020] When the parallel light L13 enters the first lens 31, it is refracted toward the top in the y direction in the drawing and is emitted as first light L23. Then, when the first light L23 enters the upper part of the second lens 32 in the y direction in the drawing, it is refracted toward the y direction and is emitted as second light L33. Thereafter, the second light L33 is irradiated to the right side of the irradiation surface 4 in the Z direction in the drawing.

[0021] That is, the parallel light L1 (L11 to L13) emitted from the light source 2 is converged by the first lens 31 and then irradiated onto the irradiation surface 4 by the second lens 32. That is, the first lens 31 and the second lens 32 expand the irradiation range S1 of the parallel light L1 (L11 to L13) to the irradiation range S2 of the second light L3 (L31 to L33).

[0022] The magnification ratio of the irradiation range S2 of the second light L3 relative to the irradiation range S1 of the parallel light L1 can be adjusted by appropriately setting the size and focal length of the first lens 31 and the second lens 32, and the emission angle of the parallel light L1 relative to the irradiation surface 4.

[0023] Fig. 2 shows a simulation result of the irradiation range of the second light L3 according to the first embodiment. As shown in Fig. 2, by using the lighting device 1, it is possible to expand the irradiation range S2 of the second light L3 and make the second light L3 linear.

[0024] As described above, the illumination device according to this embodiment includes a light source 2 that emits parallel light L1 (emitted light), a first lens 31 that receives the parallel light L1 and emits a first light L2, and a second lens 32 that receives the first light L2 and emits a second light L3. The second lens 32 emits the second light L3 at an angle relative to the irradiation surface 4. The irradiation range S2 of the second light L3 is wider than the irradiation range S1 of the parallel light L1. With this configuration, the second light L3 emitted by the second lens 32 is emitted at an angle relative to the irradiation surface 4, eliminating the need to position the light source 2 near the irradiation range S2. This allows the irradiation range of the light source to be expanded, thereby reducing the number of light sources required. Furthermore, the irradiation range S1 emitted by the light source 2 is expanded by the first lens 31 and the second lens 32 to an irradiation range S2 wider than the irradiation range S1, thereby reducing the number of light sources required.

[0025] The light source 2 is a parallel light source, which allows the parallel light L1 (emitted light) emitted from the light source 2 to enter the magnifying mechanism 3 (first lens 31 and second lens 32) without loss.

[0026] The first lens 31 and the second lens 32 are convex lenses, and thus, by providing a pinhole at the convergence point of the laser light L2 that occurs between the first lens 31 and the second lens 32, stray light can be removed.

[0027] 3 is a side cross-sectional view of an illumination device according to a second embodiment. In the second embodiment, unlike the first embodiment, the light source 2 is a diffused light source rather than a parallel light source. The light source 2 is configured using a light source such as an LED.

[0028] 3, the light source 2 emits diffused light L1a. Diffused light L11a is the light at the top of the diffused light L1a in the y direction on the drawing, diffused light L12a is the light at the center of the diffused light L1a in the y direction on the drawing, and diffused light L13a is the light at the bottom of the diffused light L1a in the y direction on the drawing. Diffused light L11a is emitted slightly upward in the y direction on the drawing, diffused light L12a is emitted in the y direction on the drawing, and diffused light L13a is emitted slightly downward in the y direction on the drawing.

[0029] The diffused light L1a is converged by the first lens 31 (first light L2a), and then irradiated onto the irradiation surface 4 by the second lens 32 (second light L3a).

[0030] The magnification ratio of the irradiation range S2a of the second light L3 relative to the irradiation range S1a of the diffused light L1a can be adjusted by appropriately setting the size and focal length of the first lens 31 and the second lens 32, and the emission angle of the diffused light L1a relative to the irradiation surface 4.

[0031] In the second embodiment, the light source 2 is a diffused light source, which allows the light source 2 to have a relatively inexpensive configuration, thereby reducing the cost of the lighting device.

[0032] 4 is a side cross-sectional view of an illumination device according to a third embodiment. The third embodiment differs from the first embodiment in that a first lens 31a is provided instead of the first lens 31. The first lens 31a is a concave lens.

[0033] 4, when the parallel light L11 enters the first lens 31a, it is refracted toward the upper side in the y direction in the drawing and is emitted as the first light L21b (L2b). Then, when the first light L21b enters the upper side in the y direction of the second lens 32 in the drawing, it is refracted toward the y direction and is emitted as the second light L31b (L3b). Then, the second light L31b is irradiated to the right side in the Z direction of the drawing of the irradiation surface 4.

[0034] When the parallel light L12 enters the first lens 31a, it passes through the first lens 31a and is emitted as first light L22b (L2b). When the first light L22b enters the center of the second lens 32 in the y direction in the drawing, it passes through the second lens 32 and is emitted as second light L32b (L3b). Then, the second light L32b is irradiated onto the center of the irradiation surface 4 in the Z direction in the drawing.

[0035] When the parallel light L13 enters the first lens 31a, it is refracted downward in the y direction in the drawing and is emitted as first light L23b (L2b). Then, when the first light L23b enters the lower part of the second lens 32 in the y direction in the drawing, it is refracted in the y direction and is emitted as second light L33b (L3b). Then, the second light L33b is irradiated to the left side of the irradiation surface 4 in the Z direction in the drawing.

[0036] That is, the parallel light L1 is diffused by the first lens 31a (first light L2b), and then irradiated onto the irradiation surface 4 by the second lens 32 (second light L3b).

[0037] The magnification ratio of the irradiation range S2b of the second light L3b relative to the irradiation range S1 of the parallel light L1 can be adjusted by appropriately setting the size and focal length of the first lens 31a and the second lens 32, and the emission angle of the parallel light L1 relative to the irradiation surface 4.

[0038] In the third embodiment, the first lens 31a is a concave lens. This reduces the refractive index of the parallel light L1 compared to when the first lens is a convex lens, thereby reducing chromatic aberration of the second light and reducing color unevenness of the second light. Furthermore, since there is no need to converge light between the first lens and the second lens, the distance between the first lens and the second lens can be reduced. This reduces the size of the lighting device.

[0039] 5A is a plan cross-sectional view of an illumination device according to a fourth embodiment, and FIG. 5B is a simulation result of an illumination range 2S′ of the second light according to the fourth embodiment. In the fourth embodiment, unlike the first embodiment, an optical element 5 is disposed between the light source 2 and the first lens 31.

[0040] In the configuration of the first embodiment, the illumination range S2 of the second light L3 is linear (see FIG. 2). The width of the illumination range S2 of the second light L3 in the X direction increases toward the right side of the drawing (+Z direction). In contrast, in the fourth embodiment, the line width of the illumination light (second light) of the lighting device 1 can be made constant (see FIG. 5(b)). That is, in the fourth embodiment, both ends in the X direction of the illumination range of the second light can be made to extend along the Z direction.

[0041] Specifically, the optical element 5 is composed of a prism, an optical diffraction element, or the like. The optical element 5 refracts the parallel light L1 and irradiates the third light L4 (L44 to L46) toward the first lens 31. Here, the optical element 5 has an even-order aspherical coefficient set on its surface in a planar view (XZ cross section) so that the line width of the illumination light (the irradiation range of the second light L3c) is approximately constant. That is, the surface shape of the optical element 5 in a planar view is expressed by an aspherical equation (even function) with even-order terms. Specifically, the optical element 5 is set in accordance with the following equation (1). Here, z is the coordinate in the optical axis direction, r is the distance from the optical axis, c is the reciprocal of the radius of curvature, k is the Conic coefficient, and α １ ~α ８ are even-order aspherical coefficients.

[0042]

[0043] As shown in Figure 5(a), parallel light L14 is the light in the parallel light L1 at the top of the drawing in the x direction, parallel light L15 is the light in the parallel light L1 at the center of the drawing in the x direction, and parallel light L16 is the light in the parallel light L1 at the bottom of the drawing in the x direction.

[0044] When the parallel light L14 enters the optical element 5, it is refracted upward in the x direction in the drawing and is emitted as third light L44 (L4). When the third light L44 enters the upper part of the first lens 31 in the x direction in the drawing, it is refracted downward in the x direction in the drawing and is emitted as first light L24c (L2c). When the first light L24c enters the lower part of the second lens 32 in the x direction in the drawing, it is refracted slightly upward in the x direction in the drawing and is emitted as second light L34c (L3c). Thereafter, the second light L31c is irradiated onto the irradiation surface 4.

[0045] When the parallel light L15 enters the center of the optical element 5 in the x direction in the drawing, it passes through the optical element 5 and is emitted as third light L45 (L4). When the third light L45 enters the center of the first lens 31 in the x direction in the drawing, it passes through the first lens 31 and is emitted as first light L25c (L2c). Then, when the first light L25c enters the center of the second lens 32 in the x direction in the drawing, it passes through the second lens 32 and is emitted as second light L35c (L3c). Thereafter, the second light L35c is irradiated onto the irradiation surface 4.

[0046] When the parallel light L16 enters the optical element 5, it is refracted downward in the x direction in the drawing and is emitted as third light L46 (L4). When the third light L46 enters the lower part of the first lens 31 in the x direction in the drawing, it is refracted upward in the x direction in the drawing and is emitted as first light L26c (L2c). When the first light L23c enters the upper part of the second lens 32 in the x direction in the drawing, it is refracted slightly downward in the x direction in the drawing and is emitted as second light L36c (L3c). Thereafter, the second light L36c is irradiated onto the irradiation surface 4.

[0047] In the fourth embodiment, the line width of the illumination light (the irradiation range of the second light L3c) is made substantially constant by appropriately setting the even-order aspherical coefficient of the surface in a planar view of the optical element 5. In Fig. 5A, the second light L31c and L33c, which are outer light of the second light L3c in the X direction, are directed inward in the X direction, thereby suppressing the second light L3c from spreading outward in the X direction and making the line width of the second light L3c substantially constant (see Fig. 5B).

[0048] In this embodiment, the optical element 5 is disposed between the light source 2 and the first lens 31, but is not limited to this. For example, the optical element 5 may be disposed between the first lens 31 and the second lens 32, or between the second lens 32 and the irradiation surface 4. In other words, the optical element 5 only needs to be disposed in the optical path of the parallel light L1 from the light source 2 to the irradiation surface 4.

[0049] (Modification) Fig. 6(a) is a plan cross-sectional view of an illumination device according to a modification of the fourth embodiment, and Fig. 6(b) shows the simulation results of the irradiation range 2Sf of the second light according to the modification of the fourth embodiment. In this modification, compared to Fig. 5(a), an optical element 5f is arranged instead of the optical element 5. The optical element 5f allows the irradiation range of the illumination light (second light) of the illumination device 1 to be asymmetric with respect to the Z direction (see Fig. 6(b)).

[0050] Specifically, the optical element 5f is composed of a prism, an optical diffraction element, or the like. The optical element 5f refracts the parallel light L1 and irradiates the third light L4f (L44f to L46f) toward the first lens 31. Here, the optical element 5f has odd-order aspherical coefficients set on its surface in a planar view (XZ cross section) so that the irradiation range S2f of the second light L3f is asymmetric with respect to the Z direction (specifically, so that it is biased in the +X direction). That is, the surface shape of the optical element 5f in a planar view is expressed by an aspherical equation (odd function) with odd-order terms. Specifically, the optical element 5f is set in accordance with the following equation (2): z is the coordinate in the optical axis direction, r is the distance from the optical axis, c is the reciprocal of the radius of curvature, k is the conic coefficient, and β １ ~β ８ are odd-order aspherical coefficients.

[0051]

[0052] As shown in FIG. 6A, when the parallel light L14 enters the optical element 5f, it is refracted upward in the x direction in the drawing and is emitted as the third light L44f (L4f). When the third light L44f enters the upper part of the first lens 31 in the x direction in the drawing, it is refracted downward in the x direction in the drawing and is emitted as the first light L24f (L2f). When the first light L24f enters the lower part of the second lens 32 in the x direction in the drawing, it is refracted slightly upward in the y direction in the drawing and is emitted as the second light L34f (L3f). The second light L34f is then irradiated onto the irradiation surface 4.

[0053] When the parallel light L15 enters the center of the optical element 5f in the x direction in the drawing, it passes through the optical element 5f and is emitted as third light L45f (L4f). When the third light L45f enters the center of the first lens 31 in the x direction in the drawing, it passes through the first lens 31 and is emitted as first light L25f (L2f). When the first light L25f enters the center of the second lens 32 in the x direction in the drawing, it passes through the second lens 32 and is emitted as second light L35f (L3f). Thereafter, the second light L32d is irradiated onto the irradiation surface 4.

[0054] When the parallel light L16 enters the optical element 5f, it passes through the optical element 5f and is emitted as third light L46f (L4f). When the third light L46f enters the first lens 31, it is refracted toward the upper x-direction in the drawing and is emitted as first light L26f (L2f). Then, when the first light L26f enters the upper x-direction of the second lens 32 in the drawing, it is refracted toward the y-direction and is emitted as second light L36f (L3f). Thereafter, the second light L36d is irradiated onto the irradiation surface 4.

[0055] In this modification, by appropriately setting the odd-order aspherical coefficient of the surface of the optical element 5f in a planar view, the irradiation range S2f of the second light L3f becomes asymmetric with respect to the Z direction. Specifically, in Fig. 6(a), the first light 24f that enters the lower part of the second lens 32 in the drawing is emitted toward the upper part of the drawing, and the first light L26f and L25f that enter the upper and central parts of the second lens 32, respectively, are emitted in the y direction, so that the irradiation range S2f of the second light L3f can be biased in the +X direction (see Fig. 6(b)).

[0056] 7A is a side cross-sectional view of an illumination device according to a fifth embodiment, and FIG. 7B shows a simulation result of an illumination range 2Sd of the second light according to the fifth embodiment. In the fifth embodiment, unlike the first embodiment, an optical element 5a is disposed between the light source 2 and the first lens 31.

[0057] In the configuration of the first embodiment, the illumination range S2 of the second light L3 is linear (see FIG. 2). The illuminance of the illumination range S2 of the second light L3 decreases toward the right side of the drawing (+Z direction). In contrast, in the fifth embodiment, the illuminance of the illumination range of the second light can be kept substantially constant (see FIG. 7B).

[0058] Specifically, the optical element 5a is composed of a prism, an optical diffraction element, or the like. The optical element 5a refracts the parallel light L1 and irradiates the third light L4a (L41a to L43a) toward the first lens 31. Here, the optical element 5a has odd-order aspherical coefficients set on its surface in a side view (YZ cross section) so that the illuminance of the second light L3d in the irradiation range S2d is constant. That is, the surface shape of the optical element 5a in a side view is expressed by an aspherical equation (odd function) with odd-order terms. Specifically, the optical element 5a is set in accordance with the above-mentioned equation (2).

[0059] 7A, when the parallel light L11 enters the optical element 5a, it is refracted toward the upper side in the y direction in the drawing and is emitted as the third light L41d (L4d). When the third light L41d enters the upper part of the first lens 31 in the y direction in the drawing, it is refracted toward the lower side in the y direction in the drawing and is emitted as the first light L21d (L2d). When the first light L21d enters the lower part of the second lens 32 in the y direction in the drawing, it is refracted toward the slightly upper side in the y direction in the drawing and is emitted as the second light L31d (L3d). The second light L31d is then irradiated to the left side of the irradiation surface 4 in the Z direction in the drawing.

[0060] When the parallel light L12 enters the center of the optical element 5a in the y direction in the drawing, it passes through the optical element 5a and is emitted as third light L42d (L4d). When the third light L42a enters the center of the first lens 31 in the y direction in the drawing, it passes through the first lens 31 and is emitted as first light L22d (L2d). Then, when the first light L22d enters the center of the second lens 32 in the y direction in the drawing, it passes through the second lens 32 and is emitted as second light L32d (L3d). Thereafter, the second light L32d is irradiated onto the center of the irradiation surface 4 in the Z direction in the drawing.

[0061] When the parallel light L13 enters the optical element 5a, it passes through the optical element 5a and is emitted as third light L43d (L4d). When the third light L43d enters the first lens 31, it is refracted toward the upper part of the drawing in the y direction and is emitted as first light L23d (L2d). Then, when the first light L23d enters the upper part of the drawing in the y direction of the second lens 32, it is refracted toward the y direction and is emitted as second light L33d (L3d). Thereafter, the second light L33d is irradiated to the left side of the drawing in the Z direction of the irradiation surface 4.

[0062] In the fifth embodiment, the illuminance of the irradiation range S2d of the second light L3d is made substantially constant by appropriately setting the odd-order aspherical coefficient of the surface of the optical element 5a in a side view. In FIG. 7A, the second light L31 in FIG. 2 is indicated by a dashed line. As shown in FIG. 7A, the second light L31d on the left side of the drawing in the Z direction of the second light L3d is irradiated further to the right in the Z direction of the drawing than the second light L31 in FIG. 2. That is, the second light L31d, which is the light irradiated near the illumination device 1, is configured to be irradiated far from the illumination device 1. This reduces the illuminance near the illumination device 1 and increases the illuminance far from the illumination device 1 in the irradiation range S1 of the second light L3d, thereby making the illuminance of the irradiation range S2d of the second light substantially constant (see FIG. 7B).

[0063] In this embodiment, the second light L31d, which is light irradiated near the illumination device 1, is configured to be irradiated far from the illumination device. However, by appropriately setting the odd-order aspherical coefficient of the surface of the optical element 5, the second light L33d, which is light irradiated far from the illumination device 1, may be configured to be irradiated near the illumination device. Even with this configuration, the illuminance of the illumination range S2d of the second light L3d can be made substantially constant. Furthermore, if the angle between the emission angle (emission angle of the parallel light L1) with respect to the illumination surface 4 of the illumination device 1 and the Z direction is small, the second light L3d will be irradiated far from the illumination device 1. In this case, by configuring the second light L33d to be irradiated near the illumination device 1, the second light L3d can be irradiated near the illumination device 1.

[0064] Furthermore, in this embodiment, the optical element 5a is disposed between the light source 2 and the first lens 31, but this is not limiting. For example, the optical element 5a may be disposed between the first lens 31 and the second lens 32, or between the second lens 32 and the irradiation surface 4. In other words, it is sufficient that the optical element 5a is disposed in the optical path along which the parallel light L1 travels from the light source 2 to the irradiation surface 4.

[0065] (Modification) Fig. 8(a) is a plan cross-sectional view of an illumination device according to a modification of the fifth embodiment, and Fig. 8(b) shows the simulation results of the irradiation range 2Sg of the second light according to the modification of the fifth embodiment. In this modification, compared to Fig. 7(a), an optical element 5g is arranged instead of the optical element 5. The optical element 5g makes it possible to make the illuminance distribution of the illumination light (second light) of the illumination device 1 symmetrical with respect to the center in the Z direction (see Fig. 8(b)).

[0066] Specifically, the optical element 5g is composed of a prism, an optical diffraction element, or the like. The optical element 5g refracts the parallel light L1 and irradiates the third light L4g (L44g to L46g) toward the first lens 31. Here, the optical element 5g has an even-order aspherical coefficient set on its surface in a side view (YZ cross section) so that the illuminance distribution of the illumination light (second light) is symmetrical with respect to the center of the drawing in the Z direction (specifically, so that the illuminance is high in the center of the drawing in the Z direction and low at both ends of the drawing). That is, the surface shape of the optical element 5g in a side view is expressed by an aspherical equation (even function) with even-order terms. Specifically, the optical element 5g is set in accordance with the above-mentioned equation (1).

[0067] As shown in Figure 8 (a), parallel light L14 is the light at the top of the drawing in the y direction of the parallel light L1, parallel light L15 is the light at the center of the drawing in the y direction of the parallel light L1, and parallel light L16 is the light at the bottom of the drawing in the y direction of the parallel light L1.

[0068] When the parallel light L14 enters the optical element 5g, it is refracted upward in the y direction in the drawing and is emitted as the third light L41g (L4). When the third light L41g enters the upper part of the first lens 31 in the y direction in the drawing, it is refracted downward in the y direction in the drawing and is emitted as the first light L21g (L2g). When the first light L21g enters the lower part of the second lens 32 in the y direction in the drawing, it is refracted slightly upward in the y direction in the drawing and is emitted as the second light L31g (L3g). The second light L31g is then irradiated onto the irradiation surface 4.

[0069] When the parallel light L15 enters the center of the optical element 5g in the y direction in the drawing, it passes through the optical element 5g and is emitted as third light L42g (L4g). When the third light L42g enters the center of the first lens 31 in the y direction in the drawing, it passes through the first lens 31 and is emitted as first light L22g (L2g). When the first light L22g enters the center of the second lens 32 in the y direction in the drawing, it passes through the second lens 32 and is emitted as second light L32g (L3g). Thereafter, the second light L32g is irradiated onto the irradiation surface 4.

[0070] When the parallel light L16 enters the optical element 5g, it is refracted downward in the y direction in the drawing and is emitted as the third light L43g (L4g). When the third light L43g enters the lower part of the first lens 31 in the y direction in the drawing, it is refracted upward in the y direction in the drawing and is emitted as the first light L23g (L2g). When the first light L23g enters the upper part of the second lens 32 in the y direction in the drawing, it is refracted slightly downward in the y direction in the drawing and is emitted as the second light L33g (L3g). The second light L33g is then irradiated onto the irradiation surface 4.

[0071] In this modification, by appropriately setting the even-order aspherical coefficient of the surface of the optical element 5g in a side view, the illuminance distribution of the second light L3g in the irradiation range S2g is symmetrical with respect to the center in the Z direction of the drawing. Specifically, in Fig. 8(a), the first light 23g that enters the lower part of the second lens 32 in the drawing is emitted toward the lower part of the drawing, the first light 22g that enters the center of the second lens 32 in the drawing is emitted in the y direction, and the first light 21g that enters the lower part of the second lens 32 in the drawing is emitted toward the upper part of the drawing, so that the second light L3 is irradiated in a concentrated manner toward the center in the Z direction of the irradiation surface 4. As a result, in the irradiation range of the second light, the illuminance is high in the center in the Z direction of the drawing and low at both ends (see Fig. 8(b)).

[0072] In this modification, the irradiation range of the second light can be set to the irradiation range 2Sg in Fig. 8(c) by appropriately setting the even-order aspherical coefficient of the surface of the optical element 5g in a side view. That is, by appropriately setting the even-order aspherical coefficient of the surface of the optical element 5g in a side view, it is possible to make the illuminance low in the center of the drawing in the Z direction and high in the left and right end portions of the drawing in the irradiation range of the second light.

[0073] Sixth Embodiment Fig. 9 is a side cross-sectional view of an illumination device according to a sixth embodiment. Fig. 10 is a perspective view of an optical element according to the sixth embodiment. In the sixth embodiment, unlike the first embodiment, an optical element 5b is disposed between the light source 2 and the first lens 31.

[0074] The optical element 5b is composed of a prism, an optical diffraction element, or the like. The optical element 5b also has the functions of the optical elements 5 and 5a. That is, the optical element 5b makes the line width of the illumination light (the irradiation range S2e of the second light L3e) approximately constant by appropriately setting the even-order aspherical coefficient of the surface of the optical element 5. The optical element 5b also makes the illuminance of the irradiation range S2e of the second light L3e approximately constant by appropriately setting the odd-order aspherical coefficient of the surface of the optical element 5b.

[0075] Fig. 11 shows a simulation result of the irradiation range of the second light according to the sixth embodiment. As shown in Fig. 11, by using the lighting device 1, it is possible to keep the illuminance of the irradiation range S2 of the illumination light (second light L3e) constant while keeping the line width of the illumination light (second light L3e) approximately constant.

[0076] In the present embodiment, the optical element 5b is disposed between the light source 2 and the first lens 31, but this is not limiting. For example, the optical element 5b may be disposed between the first lens 31 and the second lens 32, or between the second lens 32 and the irradiation surface 4. In other words, it is sufficient that the optical element 5b is disposed in the optical path along which the parallel light L1 travels from the light source 2 to the irradiation surface 4.

[0077] 12A to 12D are diagrams showing an example of an irradiation range S2e of the second light L3e irradiated onto the irradiation surface 4, according to a modification of the sixth embodiment.

[0078] In this modification, by appropriately setting the even-order and odd-order aspherical coefficients of the surface of the optical element 5b, the irradiation range S2e of the second light L3e can be set to a shape such as that shown in FIGS. 12A to 12C. For example, by appropriately setting the even-order aspherical coefficients of the surface of the optical element 5b, the width in the X direction of the irradiation range S2e of the second light L3e can be changed. Furthermore, by appropriately setting the odd-order aspherical coefficients of the surface of the optical element 5b, the width in the Z direction of the irradiation range S2e of the second light L3e can be changed. In other words, by appropriately setting the even-order and odd-order aspherical coefficients of the surface of the optical element 5b, the shape of the irradiation range S2e of the second light L3e can be arbitrarily set.

[0079] Furthermore, the shape of the irradiation range S2e of the second light L3e can be set by appropriately changing the radius of curvature of at least one of the surfaces of the first lens 31 and the second lens 32. In the example of FIG. 12(d), the irradiation range S2e of the second light L3e can be set to the shape shown in FIG. 12(d) by increasing the radius of curvature in the x direction at the center in the y direction of at least one of the first lens 31 and the second lens 32 and decreasing the radius of curvature in the x direction at both ends in the y direction. That is, by appropriately setting the radius of curvature in the x direction of the optical element 5b, the X-direction width of the irradiation range S2e of the second light L3e can be changed. Furthermore, by appropriately setting the radius of curvature in the y direction of the optical element 5b, the Z-direction width of the irradiation range S2e of the second light L3e can be changed. That is, by appropriately changing the radius of curvature of at least one of the surfaces of the first lens 31 and the second lens 32 and appropriately setting the odd-order aspherical coefficient of the surface of the optical element 5b, the shape of the irradiation range S2e of the second light L3e can be set arbitrarily.

[0080] 13 is a side cross-sectional view of an illumination device according to a seventh embodiment. The seventh embodiment differs from the sixth embodiment in that a first lens 31b is disposed in place of the optical element 5b and the first lens 31.

[0081] The first lens 31b is obtained by adding the function of the optical element 5b to the first lens 31. That is, the first lens 31b is obtained by integrating the first lens 31 and the optical element 5b.

[0082] In the seventh embodiment, the illuminance of the illumination light (second light L3e) in the irradiation range S2e can be kept constant while the line width of the illumination light (second light L3e) is kept substantially constant by using the first lens 31b in the illumination device 1. Furthermore, since the first lens 31b is formed by integrating the first lens 31 and the optical element 5b, the number of parts of the illumination device can be reduced.

[0083] In this embodiment, the first lens 31b is the first lens 31 with the function of the optical element 5b added, but the first lens 31b may be the first lens 31 with the function of either one of the optical elements 5 or 5a added. Alternatively, the first lens 31 may not have the function of any one of the optical elements 5, 5a, or 5b added, and the second lens 32 may have the function of any one of the optical elements 5, 5a, or 5b added.

[0084] Eighth Embodiment Fig. 14 is a side cross-sectional view of an illumination device according to an eighth embodiment. Fig. 15 is a perspective view of a slit according to the eighth embodiment. In the eighth embodiment, a slit 6 is disposed between a first lens 31 and a second lens 32.

[0085] 15, the slit 6 is formed in a substantially inverted triangular shape relative to the light blocking member. By disposing the slit 6 between the first lens 31 and the second lens 32, stray light at the edge portion (end portion) of the illumination range S2e of the second light L3e can be blocked, and therefore the edge portion of the illumination range S2e of the second light L3e can be made clear.

[0086] Ninth Embodiment Fig. 16(a) is a side cross-sectional view of an illumination device according to a ninth embodiment. Fig. 16(b) is a front view of a pinhole according to the ninth embodiment. In the ninth embodiment, compared to the first embodiment, a pinhole 7 (slit) is disposed between the first lens 31 and the second lens 32.

[0087] As shown in FIG. 16B , the pinhole 7 is formed in a substantially circular shape relative to the light-shielding member. Here, if the diameter of the pinhole 7 is A and the beam diameter (width of the irradiation range S1) of the collimated light L1 (emitted light) is Φ, then 0.004×Φ≦A≦0.01×Φ holds. Furthermore, the pinhole 7 is located at a focal length F1 of the first lens 31 relative to the first lens 31, and at a focal length F2 of the second lens 32 relative to the second lens 32. Furthermore, the pinhole 7 is positioned on the optical axis of the collimated light L1. By positioning the pinhole 7 between the first lens 31 and the second lens 32, stray light at the edge (end) of the irradiation range of the second light L3 can be blocked, thereby making the edge of the irradiation range of the second light L3 clearer.

[0088] The pinhole 7 does not have to be approximately circular, but may be an approximately regular polygon such as an approximately regular hexagon or an approximately regular octagon, and may have any shape as long as the diameter A of the pinhole 7 satisfies the above conditions.

[0089] (Examples of Arrangement of Illumination Devices) (Arrangement Example 1) Fig. 17 is a plan view showing an example of the arrangement of an illumination system. As shown in Fig. 17 , the illumination system in this arrangement example includes a plurality of (four in this case) illumination devices 1. In Fig. 17 , the plurality of illumination devices 1 are arranged at equal intervals in the X direction. With this arrangement, linear illumination light (irradiation range S2 of the second light) can be arranged in the horizontal direction on the irradiation surface 4.

[0090] (Arrangement Example 2) Fig. 18 is a plan view showing an arrangement example of a lighting system. As shown in Fig. 18, the lighting system in this arrangement example includes multiple (three here) lighting devices 1. In Fig. 18, the multiple lighting devices 1 are arranged side by side at equal intervals in the Z direction. Furthermore, the illumination ranges S2 of the illumination light (second light L3) emitted by each lighting device 1 are arranged so as to overlap in the Z direction. With this arrangement, one line of illumination light (illumination range S2 of the second light) can be extended in the Z direction.

[0091] (Arrangement Example 3) FIG. 19 is a plan view showing an arrangement example of a lighting system. As shown in FIG. 19, the lighting system in this arrangement example includes multiple (here, three) lighting devices 1 (1a to 1c). In FIG. 19, the lighting devices 1a to 1c are arranged side by side at equal intervals in the Y direction. In FIG. 19, the illumination ranges of the lighting devices 1a to 1c are illustrated as illumination ranges S21 to S23. That is, in the example of FIG. 19, the lighting device 1 arranged at the top of the drawing in the Y direction irradiates the illumination light (second light) onto the illumination surface 4 on the right side of the drawing, the lighting device 1 arranged at the top center in the Y direction irradiates the illumination light (second light) onto the illumination surface 4 in the center of the drawing, and the lighting device 1 arranged at the bottom of the drawing in the Y direction irradiates the illumination light (second light) onto the illumination surface 4 on the left side of the drawing. In this way, by arranging multiple lighting devices side by side in the Y direction, a single line of illumination light (irradiation range S2 of the second light) can be extended in the Z direction.

[0092] 19 has been described taking as an example a case where multiple lighting devices 1 (1a to 1c) are lined up in the Y direction, but this is not limiting. The multiple lighting devices 1 may be positioned differently in at least one of the X direction and the Z direction. That is, the multiple lighting devices 1 may be arranged at different positions in the Y direction.

[0093] (Arrangement Example 4) Fig. 20 is a plan view showing an arrangement example of the lighting devices. As shown in Fig. 20, lighting devices 1d to 1f irradiate illumination light (second light) onto irradiation surface 4. In Fig. 20, the illumination ranges of lighting devices 1a to 1c, respectively, are illustrated as illumination ranges S24 to S26.

[0094] As shown in FIG. 20 , the illumination ranges S24 to S26 have different lengths in the Z direction. In this example, the length of the illumination range of the illumination device 1 in the Z direction can be set by appropriately changing the exit angle (exit angle of the parallel light L1) with respect to the illumination surface 4 of the illumination device 1. In the example of FIG. 20 , the illumination device 1d has a smaller angle between the illumination surface 4 and the Z direction, so the length of the illumination range S24 in the Z direction is longer. The illumination device 1f has a larger angle between the illumination surface 4 and the Z direction, so the length of the illumination range S26 in the Z direction is shorter. In this way, the length of the illumination range of the illumination device 1 in the Z direction can be set by appropriately changing the exit angle with respect to the illumination surface 4 of the illumination device 1.

[0095] 20, the left ends of the illumination ranges S24 to S26 of the illumination devices 1d to 1f in the Z direction are aligned with the X direction. In this example, by appropriately setting the positions of the illumination devices 1d to 1f in the Y direction, the left ends of the illumination ranges S24 to S26 in the Z direction can be aligned with the X direction.

[0096] In the above-described examples of the arrangement of the lighting device, the lighting device used as the lighting device 1 may be any of the lighting devices according to the first to eighth embodiments.

[0097] Furthermore, in each of the above-described examples of the arrangement of the lighting devices, the number of lighting devices 1 to be arranged is not limited to the above-described examples.

[0098] Other Embodiments As described above, the embodiments have been described as examples of the technology disclosed in the present application. However, the technology in the present disclosure is not limited to these, and can be applied to embodiments in which modifications, substitutions, additions, omissions, etc. are made as appropriate.

[0099] The light source 2 may be configured with a single light source or may be configured with a plurality of light sources. When the light source 2 is configured with a plurality of light sources, the plurality of light sources may be arranged in an array.

[0100] The lighting device of the present disclosure can be applied to lighting devices that irradiate light onto the wall surfaces of buildings, road surfaces, and the like.

[0101] REFERENCE SIGNS LIST 1 Illumination device 2 Light source (parallel light source) 2a Light source (diffused light source) 3 Magnification mechanism 31, 31a, 31b First lens 32 Second lens 4 Irradiation surface 5, 5a, 5b, 5f, 5g Optical element 6 Slit 7 Pinhole L1 Parallel light (emitted light) L1a Diffused light (emitted light) L2, L2a, L2b, L2d, L2e, L2f, L2g First light L3, L3a, L3b, L3c, L3d, L3e, L3f, L3g Second light S1 Irradiation range S2, S2a, S2b, S2d, S2e, S2f, S2g, S2', S21 to S26 Irradiation range

Claims

1. An illumination device comprising: a light source that emits an output light; a first lens that receives the output light and emits a first light; and a second lens that receives the first light and emits a second light, wherein the second lens emits the second light at an angle relative to an illumination surface, and the illumination range of the second light is wider than the illumination range of the output light.

2. The illumination device of claim 1, wherein the light source comprises a parallel light source.

3. The lighting device of claim 1, wherein the light source comprises a diffuse light source.

4. The lighting device according to claim 1, wherein the first lens and the second lens are convex lenses.

5. The lighting device according to claim 1, wherein the first lens is a concave lens, and the second lens is a convex lens.

6. The illumination device according to claim 1, further comprising an optical element arranged in an optical path from the light source to the irradiation surface, the second light being line-shaped, and the optical element having an even-order aspheric coefficient set on its surface so that the width of the second light is approximately constant.

7. The lighting device according to claim 1, further comprising an optical element arranged in an optical path from the light source to the irradiation surface, the second light being line-shaped, and the optical element having an odd-order aspheric coefficient set on its surface so that the illuminance of the second light in the longitudinal direction is approximately constant.

8. The lighting device according to claim 1, further comprising an optical element disposed in an optical path from the light source to the irradiation surface, the optical element having a surface curvature set in accordance with the shape of the second light on the irradiation surface.

9. An illumination device according to any one of claims 6 to 8, wherein the optical element is either the first lens or the second lens.

10. The lighting device according to claim 1, further comprising a slit disposed between said first lens and said second lens for blocking stray light at an irradiation end of said second light.

11. The illumination device of claim 10, wherein the slit is a pinhole.

12. The lighting device according to claim 1, wherein the second light is linear, and the length of the second light changes depending on the emission angle of the emitted light and the angle between the emitted light and the irradiation surface.

13. The illumination device according to claim 1, further comprising an optical element disposed in an optical path from the light source to the illumination surface, the optical element having a surface shape in a planar view expressed by an aspheric equation with even-order terms.

14. The illumination device according to claim 1, further comprising an optical element disposed in an optical path extending from said light source to said illumination surface, said optical element having a surface shape in a planar view expressed by an aspheric equation with odd-order terms.

15. The illumination device according to claim 1, further comprising an optical element disposed in an optical path extending from the light source to the illumination surface, the optical element having a surface shape in a side view expressed by an aspheric equation with odd-order terms.

16. The illumination device according to claim 1, further comprising an optical element disposed in an optical path from the light source to the illumination surface, the optical element having a surface shape in a side view expressed by an aspheric equation with even-order terms.

17. A lighting system comprising a plurality of lighting devices according to any one of claims 1 to 16.

18. The lighting system according to claim 17, wherein the second light in each of the lighting devices is linear, and the plurality of lighting devices are arranged side by side in a width direction of the second light.

19. The lighting system according to claim 17, wherein the second light in each of the lighting devices is linear, and the plurality of lighting devices are arranged side by side in a longitudinal direction of the second light.

20. The lighting system of claim 17, wherein the second light in each of the lighting devices is linear, and the multiple lighting devices are arranged side by side in a direction perpendicular to the length and width of the second light.

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