Lighting device

Abstract

Reduce the number of light sources. [Solution] The lighting device 1 comprises a light source 2 that emits light, a first lens 31 that receives the emitted light and emits a first light L2, a second lens 32 that receives the first light L2 and emits a second light L3, and a stray light suppression unit for suppressing stray light. The irradiation range S2 of the second light L3 is wider than the irradiation range S1 of the emitted light.

Description

Technical Field

[0001] The present disclosure relates to a lighting device.

Background Art

[0002] Conventionally, line lighting units that illuminate a linear region with arbitrary illuminance are known (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, lighting devices for illuminating the outer wall of a building are known. In such a lighting device, a predetermined region of the outer wall of the building is illuminated by embedding a light source such as an LED in the outer wall of the building or arranging the light source along the outer wall. However, in such a configuration, since the light source needs to be arranged in the vicinity of the region (irradiation range) to be illuminated, the irradiation range of the light source becomes narrow. For this reason, it is necessary to arrange a large number of light sources on the outer wall of the building, which causes problems in maintainability and cost of the lighting device.

[0005] Accordingly, an object of the present disclosure is to provide a lighting device that can reduce the number of light sources.

Means for Solving the Problems

[0006] To achieve the above object, a lighting device according to an embodiment of the present disclosure includes: a light source that emits outgoing light; a first lens that receives the outgoing light and emits first light; a second lens that receives the first light and emits second light; and a stray light suppressing portion for suppressing stray light, wherein an irradiation range of the second light is wider than an irradiation range of the outgoing light. [Effects of the Invention]

[0007] According to this disclosure, the number of light sources can be reduced. [Brief explanation of the drawing]

[0008] [Figure 1] A side cross-sectional view of the lighting device according to the first embodiment. [Figure 2] A side cross-sectional view of the first lens portion according to the first embodiment. [Figure 3] A perspective view of the second lens according to the first embodiment. [Figure 4] Simulation results of the irradiation range of the second light according to the first embodiment. [Figure 5] A diagram showing a lighting device according to the second embodiment. [Figure 6] A side cross-sectional view of the lighting device according to the third embodiment. [Figure 7] A side cross-sectional view of the lighting device according to the fourth embodiment. [Figure 8] A diagram illustrating the second lens according to the fifth embodiment. [Figure 9] A diagram showing the second lens according to the fifth embodiment. [Figure 10] A figure showing another example of the second lens according to the fifth embodiment. [Figure 11] A diagram showing a second lens according to the sixth embodiment. [Figure 12] A diagram showing the second lens according to the seventh embodiment. [Figure 13] A side cross-sectional view of the lighting device according to the eighth embodiment. [Modes for carrying out the invention]

[0009] Embodiments of the present disclosure will be described in detail below with reference to the drawings. The following description of preferred embodiments is essentially illustrative and is not intended to limit the present invention, its applications, or its uses. In the following description, the same parts are denoted by the same reference numerals, and detailed descriptions are omitted where appropriate.

[0010] (First Embodiment) Figure 1 is a side cross-sectional view of the lighting device according to the first embodiment. As shown in Figure 1, the lighting device 1 is a lighting device used for illuminating an irradiation surface 5 such as a wall surface of a building or a road surface of a road, and irradiates the irradiation surface 5 with linear irradiation light (second light L3). The lighting device 1 is installed such that the optical axis of the parallel light L1 emitted by the light source 2 is parallel to the irradiation surface 5.

[0011] In the following description, the depth direction of the drawing in Figure 1 is defined 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. It is also assumed that the irradiation surface 5 extends in the X direction and the Z direction. In the following description, the light emitted from the light source 2 may be indicated by arrows.

[0012] As shown in Figure 1, the lighting device 1 includes a light source 2, an expansion mechanism 3, and a housing 4.

[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 composed of an LED or the like. The light source 2 may be a white laser light source, or a monochromatic laser light source of red, blue, or the like.

[0014] The housing 4 is a housing that accommodates the light source 2 and the expansion mechanism 3. The housing 4 is formed, for example, in a substantially cylindrical shape extending in the Z direction. In the present embodiment, the housing 4 is installed such that its longitudinal direction is parallel to the irradiation surface 5.

[0015] The expansion mechanism 3 expands the irradiation range of the parallel light L1 (L11 to L13) received from the light source 2. Specifically, the expansion 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 such that their central portions coincide with the Z direction (the traveling direction of the parallel light L12). That is, the first lens 31 and the second lens 32 are arranged such that their central portions coincide with the optical axis direction at the central portion of the parallel light L1.

[0016] The first lens 31 receives parallel light L1 from the light source 2 and outputs first light L2 (L21 to L23). The first lens 31 is a concave lens with a concavely formed incident surface and a planarly formed exit surface.

[0017] Figure 2 shows a side cross-sectional view of the first lens unit according to the first embodiment. As shown in Figure 2, on the incident surface of the first lens 31, a concave portion 31a is formed at the central part, and a convex portion 31b is formed at the outer peripheral part. In the present embodiment, the convex portion 31b corresponds to the stray light suppression portion.

[0018] As shown in Figure 1, the second lens 32 receives the first light L2 from the first lens 31 and outputs second light L3 (L31 to L33).

[0019] Figures 3(a) and 3(b) are perspective views of the second lens according to the first embodiment. As shown in Figures 3(a) and 3(b), the second lens 32 is formed such that its incident surface 32a has a predetermined shape, and its exit surface 32b is formed in a convex shape.

[0020] Specifically, in the second lens 32, even-order aspheric coefficients of the incident surface 32a in a plan view (XZ cross section) are set such that the line width (width in the X direction) of the irradiation range S2 of the illumination light L3 is constant. For example, the shape of the incident surface 32a of the second lens 32 in a plan view is represented by an even-order term aspheric expression (even function). The shape of the incident surface 32a of the second lens 32 in a plan view is set according to the following formula (1). Note that 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 α1 to α8 are even-order aspheric coefficients.

[0021] [Mathematical Formula]

[0022] Furthermore, the second lens 32 has odd-order aspherical coefficients set for the incident surface 32a in a side view (YZ cross section) so that the illuminance in the irradiation range S2 of the illumination light L3 is constant. For example, the shape of the incident surface 32a of the second lens 32 in a side view is represented by an odd-order aspherical equation (odd function). The shape of the incident surface 32a of the second lens 32 in a plan view is set according to the following equation (2). Hereinafter, Z is the coordinate in the direction of the optical axis, r is the distance from the optical axis, c is the reciprocal of the radius of curvature, k is the conic coefficient, and β1 to β8 are even-order aspherical coefficients.

[0023]

number

[0024] As shown in Figure 1, the parallel light L1 emitted from the light source 2 has a constant illumination range S1 in the X and Y directions. Parallel light L11 is the light at the top of the diagram in the Y direction of parallel light L1, parallel light L12 is the light at the center of the diagram in the Y direction of parallel light L1, and parallel light L13 is the light at the bottom of the diagram in the Y direction of parallel light L1.

[0025] When the parallel light L11 enters the convex portion 31b of the first lens 31, it is refracted upward in the Y direction and emitted as the first light L21. Then, when the first light L21 enters the upper part of the second lens 32 in the Y direction, it is refracted downward in the Y direction and emitted as the second light L31. Subsequently, the second light L31 is projected onto the left side of the illumination surface 5 in the Z direction.

[0026] When the parallel light L12 enters the recess 31a of the first lens 31, it passes through the first lens 31 and is emitted as the first light L22. Then, when the first light L22 enters the center of the drawing in the Y direction of the second lens 32, it is refracted slightly downward in the drawing in the Y direction and is emitted as the second light L32. Subsequently, the second light L32 illuminates the center of the drawing in the Z direction of the illumination surface 5.

[0027] When the parallel light L13 enters the convex portion 31b of the first lens 31, it is refracted downward in the Y direction and emitted as the first light L23. Then, when the first light L23 enters the upper part of the second lens 32 in the Y direction, it is refracted slightly upward in the Y direction and emitted as the second light L33. Subsequently, the second light L33 illuminates the right side of the illumination surface 5 in the Z direction.

[0028] In other words, the parallel light L1 (L11~L13) emitted from the light source 2 is diffused by the first lens 31 and then irradiated onto the illumination surface 5 by the second lens 32. That is, the illumination range S1 of the parallel light L1 (L11~L13) is expanded by the first lens 31 and the second lens 32 to the illumination range S2 of the second light L3 (L31~L33).

[0029] Figure 4 shows the simulation results of the irradiation range of the second light according to the first embodiment. As shown in Figure 4, by using the illumination device 1, the irradiation range S2 of the second light L3 can be expanded while making the second light L3 appear in a line shape.

[0030] Furthermore, the magnification ratio of the illumination range S2 of the second light L3 relative to the illumination 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 with respect to the illumination surface 5. Also, as shown in Figure 4, the illumination device 1 emits a linear illumination light (second light L3), and here, linear means that the line width at one end in the Z direction of the illumination light is about 1 to 5 times the line width at the other end in the Z direction.

[0031] Here, stray light may occur within the housing 4. For example, if the protrusion 31b is not formed on the first lens 31, when parallel light L11 enters the first lens 31, it is emitted as first light L21a. At this time, the first light L21a is greatly refracted toward the upper part of the diagram in the Y direction, so it cannot enter the second lens 32 directly and instead enters the inner wall of the housing 4 (see Figure 1). As a result, the first light L21a becomes stray light.

[0032] In contrast, in the first embodiment, a convex portion 31b is formed on the incident surface of the first lens 31. As a result, when the first light L21 (parallel light L11) is incident on the convex portion 31b, it is focused by the convex portion 31b and is not significantly refracted toward the upper part of the drawing in the Y direction, but instead is incident directly on the second lens 32. Therefore, stray light can be suppressed.

[0033] (Second Embodiment) Figure 5(a) is a side cross-sectional view of the lighting device according to the second embodiment. In the second embodiment, compared to the first embodiment, a first light-shielding plate 61 (stray light suppression part) is arranged between the first lens 31 and the second lens 32. In each embodiment described below, the first lens 31 is shown as not having a convex portion 31b on the incident surface, but as shown in Figure 2, the first lens 31 may have a convex portion 31b on the incident surface.

[0034] The first light-shielding plate 61 is a light-shielding plate positioned between the first lens 31 and the second lens 32.

[0035] Figure 5(b) is a front view (viewed from the Z direction) of the first light-shielding plate according to the second embodiment. The first light-shielding plate 61 is formed in a semi-circular shape when viewed from the front.

[0036] As described above, stray light may occur within the housing 4. For example, as shown in Figure 5(a), when parallel light L1 is incident near the upper end of the drawing in the Y direction of the first lens 31, it is emitted from the first lens 31 as first light L21b. At this time, the first light L21b is greatly refracted toward the upper part of the drawing in the Y direction, so it cannot directly incident on the second lens 32 and instead incident on the inner wall of the housing 4. As a result, the first light L21b becomes stray light.

[0037] In contrast, in the second embodiment, the first light L21b is blocked by the first light-shielding plate 61. This makes it possible to suppress stray light.

[0038] Figure 5(c) is a front view (viewed from the Z direction) showing another example of the first light shield according to the second embodiment. As shown in Figure 5(c), the first light shield 61 may be formed in an arc shape when viewed from the front. In this case, it becomes easier to install the first light shield 61 on the lighting device.

[0039] (Third embodiment) Figure 6 is a side cross-sectional view of the lighting device according to the third embodiment. In the second embodiment, one first light-shielding plate 61 was placed between the first lens 31 and the second lens 32, but in the third embodiment, a plurality (in this case, three) of first light-shielding plates 61 (stray light suppression units) are placed between the first lens 31 and the second lens 32.

[0040] As described above, stray light may occur within the housing 4. For example, as shown in Figure 6, when the first light L1 is incident near the upper end of the drawing in the Y direction of the first lens 31, it is emitted from the first lens 31 as first light L21b and L21c. At this time, the first light L11b and L11c are greatly refracted toward the upper part of the drawing in the Y direction, and thus incident on the inner wall of the housing 4 near the first lens 31 (the inner wall on the left side of the drawing). If we try to block these first light L21b and L21c with a single first light-shielding plate 61, the length of the first light-shielding plate 61 in the Y direction needs to be increased. As a result, the first light L21 (effective light), which does not need to be blocked, is blocked (see Figure 5), and the amount of light in the second light L3, which is the illumination light, decreases.

[0041] In contrast, in the third embodiment, a plurality of first light-shielding plates 61 are arranged between the first lens 31 and the second lens 32. This allows the first light L21b and 21c to be shielded without shielding the first light L21 (effective light), even without increasing the length of each first light-shielding plate 61 in the Y direction. This makes it possible to increase the illuminance of the illumination light while suppressing stray light.

[0042] (Fourth Embodiment) Figure 7 is a side cross-sectional view of the lighting device according to the fourth embodiment. In the fourth embodiment, a second light-shielding plate 62 (stray light suppression unit) is arranged between the second lens 32 and the illumination surface 5.

[0043] The second light-shielding plate 62 is a light-shielding plate positioned between the second lens 32 and the illumination surface 5. Specifically, the second light-shielding plate 62 is provided on the outside of the lighting device 1 (housing 4).

[0044] As described above, stray light may occur within the housing 4. For example, as shown in Figure 7, when the first light L1 is incident near the upper end of the drawing in the Y direction of the first lens 31, it is emitted from the first lens 31 as the first light L21d. At this time, the first light L21d is greatly refracted toward the upper part of the drawing in the Y direction, so it cannot directly incident on the second lens 32 and instead incident on the inner wall of the housing 4. After the first light L21d is incident on the second lens 32, it is emitted as the second light L31a outside the irradiation range S2 of the second light L3 (specifically, to the left of the irradiation range S2 in the drawing). In other words, the second light L31a is stray light.

[0045] In contrast, in the fourth embodiment, a second light-shielding plate 62 is placed between the second lens 32 and the illumination surface 5. This allows stray light, the second light L31a, to be blocked outside the illumination device 1. Furthermore, the light-shielding plate can be installed more easily than if it were installed inside the housing 4.

[0046] (Fifth embodiment) Figure 8 is a diagram illustrating the second lens according to the fifth embodiment. Specifically, Figure 8(a) is a front view of the second lens 32 (viewed from the Z direction), Figure 8(b) is a side view of the second lens 32 (viewed from the X direction), and Figure 8(c) is a top view of the second lens 32 (viewed from the X direction).

[0047] As shown in Figure 8, the second lens 32 has an H-cut portion 321 and an edge portion 322 formed on the outer circumference on the incident surface 32a side. The H-cut portion 321 is formed to suppress rotation of the second lens 32 when the second lens 32 is fixed inside the housing 4. The edge portion 322 is formed to fix the second lens 32 to the lens ring (not shown) inside the housing 4.

[0048] Here, as shown in Figure 8(b), when the first light L21e, which is light emitted from the first lens 31, is incident on the edge portion 322 at the top of the drawing in the Y direction, the first light L21e may undergo Fresnel reflection and become stray light.

[0049] Therefore, in the fifth embodiment, the edge portion 322 at the top of the drawing is painted black.

[0050] Figure 9 shows a second lens according to the fifth embodiment. Specifically, Figure 9(a) is a front view of the second lens 32, and Figure 9(b) is a side view of the second lens 32.

[0051] As shown in Figure 9, a black-painted portion 322a (stray light suppression portion) is formed on the upper edge portion 322 of the drawing. Because the upper edge portion 322 of the drawing is black-painted, when the first light L21e is incident on the upper edge portion 322 of the drawing, the first light L21c is absorbed by the black-painted portion 322a, thereby suppressing stray light. In addition, the edge portion 322 may be roughened instead of black-painted, or it may be black-painted and roughened.

[0052] Figure 10 shows another example of the second lens according to the fifth embodiment. Specifically, Figure 10(a) is a front view of the second lens 32, and Figure 10(b) is a side cross-sectional view of the second lens 32.

[0053] In Figure 9, only the upper edge portion 322 of the drawing was blackened, but in Figure 10, the entire edge portion 322 is blackened (blackened portion 322a). As a result, the first light L2 incident on the edge portion 322 is absorbed by the blackened portion of the edge portion 322, thereby suppressing stray light. In addition, the blackening process of the edge portion 322 becomes easier. Note that, as in Figure 9, the edge portion 322 may be roughened instead of blackened, or it may be blackened and roughened.

[0054] (Sixth Embodiment) Figure 11 shows a second lens according to the sixth embodiment. Specifically, Figure 11(a) is a front view of the second lens 32, and Figure 11(b) is a side view of the second lens 32. In Figure 11, the outer peripheral end of the second lens 32 on the emission surface 32b side is painted black.

[0055] As shown in Figure 11, a black-coated portion 322b (stray light suppression portion) is formed on the outer peripheral end of the second lens 32 on the side of the emission surface 32b. Because the outer peripheral end of the second lens 32 on the side of the emission surface 32b is black-coated, when the first light L21e is incident on the edge portion at the top of the drawing, the first light L21e is absorbed by the black-coated portion, thereby suppressing stray light. In addition, the outer peripheral end of the second lens 32 on the side of the emission surface 32b may be roughened instead of black-coated, or it may be black-coated and roughened.

[0056] (Seventh Embodiment) Figure 12(a) is a side view showing the peripheral portion of the second lens according to the seventh embodiment, and Figure 12(b) is a front view of the third light-shielding plate according to the seventh embodiment. In the seventh embodiment, the third light-shielding plate 63 (stray light suppression portion) is arranged near the edge portion 322 on the incident surface 32a side of the second lens 32.

[0057] The third light-shielding plate 63 is a light-shielding plate positioned near the edge portion 322 at the top of the drawing, and is formed in an arc shape to correspond to the shape of the edge portion 322 at the top of the drawing.

[0058] As shown in Figure 12(a), the first light L21e attempting to enter the edge portion 322 at the top of the drawing is blocked by the third light-shielding plate 63. In other words, the third light-shielding plate 63 is provided so that the first light L21c does not enter the edge portion 322. This makes it possible to suppress stray light.

[0059] Figure 12(c) is a front view showing another example of the third light-shielding plate according to the seventh embodiment. As shown in Figure 12(c), the third light-shielding plate 63 may be formed in an arc shape when viewed from the front. In this case, it becomes easier to install the third light-shielding plate 63 on the lighting device.

[0060] (Eighth embodiment) Figure 13 is a side cross-sectional view of the lighting device according to the eighth embodiment. In the eighth embodiment, similar to the first embodiment, the lighting device 1 is installed such that the optical axis P1 of the parallel light L1 emitted by the light source 2 is parallel to the illumination surface 5.

[0061] Here, the central part P2 of the second lens 32 is positioned on the illumination surface 5 side with respect to the optical axis P1 (parallel light L11) of the parallel light L1 of the light source 2. In other words, the central part P2 of the second lens 32 is decentered towards the illumination surface 5 side with respect to the optical axis P1 of the light source 2.

[0062] Because the central part P2 of the second lens 32 is decentered to the illumination surface 5 side with respect to the optical axis of the light source 2, even when the illumination device 1 is installed so that the optical axis of the parallel light L1 emitted by the light source 2 is parallel to the illumination surface 5, the illumination device 1 can still project a linear illumination light onto the illumination surface 5. This expands the illumination range of the illumination device while making it easier to install.

[0063] (Other embodiments) As described above, embodiments have been explained as examples of the technology disclosed in this application. However, the technology in this disclosure is not limited thereto and may be modified, replaced, or adapted as appropriate. This can also be applied to embodiments in which additions, omissions, etc., have been made.

[0064] Light source 2 may consist of a single light source or multiple light sources. If light source 2 consists of multiple light sources, the multiple light sources may be arranged in an array. [Industrial applicability]

[0065] The lighting device described herein can be applied to lighting devices that irradiate light onto building walls, road surfaces, and the like. [Explanation of symbols]

[0066] 1. Lighting device 2 light source 3. Expansion mechanism 31. First lens 31a Recess 31b Convex part 32. Second lens 322 Koba 322a, 322b Black painted section 4 cabinets 5 Irradiation surface 61 1st light shielding plate 62 2nd light shielding plate 63 Third light shielding plate L1 parallel light (outgoing light) L2 1st light L3 Second Light S1, S2 Irradiation Area P1 optical axis P2 Second lens center

Claims

1. A light source that emits light, A first lens that receives the aforementioned emitted light and emits first light, A second lens that receives the first light and emits the second light, It is equipped with a stray light suppression unit to suppress stray light, A lighting device in which the irradiation range of the second light is wider than the irradiation range of the emitted light.

2. The lighting device according to claim 1, wherein the optical axis of the emitted light is arranged to be parallel to the illumination surface to which the second light is irradiated.

3. The lighting device according to claim 1, wherein the first lens has a recess formed in the center and a convex portion formed on its outer circumference.

4. The lighting device according to claim 1, wherein the stray light suppression unit includes a first light shielding plate provided between the first lens and the second lens.

5. The lighting device according to claim 3, wherein the first light-shielding plate is formed in a semi-circular or circular arc shape.

6. The lighting device according to claim 1, wherein the stray light suppression unit includes a plurality of first light-shielding plates provided between the first lens and the second lens.

7. The lighting device according to claim 1, wherein the stray light suppression unit includes a second light shielding plate provided between the second lens and the illumination surface.

8. The illumination device according to claim 1, wherein the second lens has an edge portion provided on the outer circumference of the incident surface side into which the first light enters.

9. The lighting device according to claim 8, wherein the stray light suppression unit is provided on the edge portion.

10. The lighting device according to claim 8, wherein the stray light suppression unit is provided on the outer periphery of the output side from which the second light is emitted.

11. The lighting device according to claim 8, wherein the stray light suppression unit includes a third light-shielding plate provided so that the first light does not enter the edge portion.

12. A light source that emits light, A first lens that receives the aforementioned emitted light and emits first light, It comprises a second lens that receives the first light and emits a second light, The optical axis of the emitted light is positioned parallel to the irradiation surface to which the second light is irradiated. An illumination device in which the central part of the second lens is positioned on the illumination surface side with respect to the optical axis of the emitted light.

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