Lighting device
The lighting device addresses sink marks and stray light issues by employing convex lenses and reflective surfaces, enhancing optical efficiency and reducing costs through optimized manufacturing processes.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD
- Filing Date
- 2024-11-07
- Publication Date
- 2026-06-05
AI Technical Summary
Conventional lighting devices with a cutoff function face issues such as sink marks on flat emission surfaces, increased costs due to separate machining of lens surfaces, and stray light generation due to concave and processed exit surfaces, leading to reduced optical efficiency and increased costs.
A lighting device design featuring a first lens with a convex emission surface and a second lens with anamorphic curvature, combined with reflective surfaces to control light direction and suppress stray light, while minimizing manufacturing complexity and costs.
The design effectively suppresses stray light generation and maintains optical efficiency while reducing manufacturing costs by using convex lenses and reflective surfaces, ensuring advanced light distribution performance.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to a lighting device having a cutoff function.
Background Art
[0002] Conventionally, there are lighting devices having a cutoff function. For example, in a projector used outdoors on the ground, the light irradiated in a predetermined direction is cut so that light does not leak to the periphery of the ground.
[0003] In Patent Document 1, the second reflecting surface formed on the first lens reflects the light incident on the upper part of the first lens downward, and cuts the light incident on the upper part of the second lens. Further, the light reflected by the second reflecting surface is superimposed on the light not reflected by the second reflecting surface and is incident on the lower part of the second lens. Since the light incident portion of the second lens is formed in a convex shape, the light incident on the side wall (side surface portion) of the second lens can be reduced. Thereby, in Patent Document 1, stray light and a decrease in optical efficiency are prevented.
Prior Art Documents
Patent Documents
[0004]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0005] By the way, although the emission surface of the first lens in Patent Document 1 is flat, when the first lens is produced by molding, sink marks are likely to occur on the emission surface of the first lens. In particular, when the first lens is rapidly cooled in order to shorten the manufacturing time of the first lens, the emission surface of the first lens is likely to become concave.
[0006] Furthermore, when the second lens is manufactured by mold forming, a machining radius (R) is applied to the upper part of the ejection surface. While it is possible to reduce the machining radius by manufacturing the side portion and the ejection surface portion of the second lens separately, this would require the creation of multiple molds, significantly increasing costs.
[0007] If the exit surface of the first lens is concave and the exit surface of the second lens has a processed radius (R) on its upper surface, the light incident from the light-emitting element on the exit surface of the first lens is refracted upward at the exit surface of the first lens due to the concave lens effect of the first lens, and then refracted further upward at the exit surface of the second lens due to the processed radius formed on the exit surface of the second lens. As a result, light is emitted upward from the exit surface of the second lens, causing stray light to be generated.
[0008] The present invention aims to provide a lighting device that has a cutoff function and can suppress the generation of stray light while keeping costs down. [Means for solving the problem]
[0009] To achieve the above objective, an illumination device according to one embodiment of the present invention comprises a light-emitting element, a first lens that receives light emitted from the light-emitting element and emits a first emitted light, and a second lens that receives the first emitted light and emits a second emitted light. The first lens has a first emitted surface that emits the first emitted light, which is formed in a convex shape that protrudes in the optical axis direction of the light-emitting element. [Brief explanation of the drawing]
[0010] [Figure 1] A side view of the lighting device according to this embodiment. [Figure 2] A plan view of the second lens and diffuser plate according to this embodiment. [Figure 3] Side view of a conventional lighting device. [Modes for carrying out the invention]
[0011] Embodiments of the present invention 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 any way.
[0012] Figure 1 shows a side view of the lighting device according to this embodiment, and Figure 2 shows a plan view of the second lens and diffuser plate according to this embodiment. As shown in Figure 1, the lighting device comprises a light-emitting element 1, a first lens 2, a second lens 3, and a diffuser plate 4. In the following description, the Z direction is the direction in which the optical axis of the light-emitting element 1 extends, the Y direction is the vertical direction, and the X direction is the direction perpendicular to the Y and Z directions. The first lens 2, the second lens 3, and the diffuser plate 4 are each made using transparent resin. The first lens 2, the second lens 3, and the diffuser plate 4 are made using, for example, polypropylene, polyethylene, polyethylene terephthalate, polyvinyl chloride, ABS resin, acrylic, polyamide, polycarbonate, Teflon®, etc.
[0013] The light-emitting element 1 is composed of an LED or the like and has an optical axis in the Z direction.
[0014] The first lens 2 receives light emitted from the light-emitting element 1 and emits the first emitted light to the second lens 3. Specifically, the first lens 2 has a first entrance opening 21, a first emission surface 22, and a first side surface portion 23 provided between the first entrance opening 21 and the first emission surface 22.
[0015] The first entrance port 21 is formed on the left side of the first lens 2 in the diagram and is concave in shape so as to surround the light-emitting element 1. The first entrance port 21 receives light emitted from the light-emitting element 1.
[0016] The first side portion 23 includes a first reflective surface 24 and a second reflective surface 25.
[0017] The first reflecting surface 24 is formed so as to extend obliquely upward to the right in the drawing and in the X direction from the upper end of the opening of the first entrance 21. The first reflecting surface 24 reflects the light incident on the first lens 2 from the first entrance 21 toward the first exit surface 22 side or the second reflecting surface 25 side.
[0018] The second reflecting surface 25 is formed so as to extend obliquely downward to the left in the drawing and in the X direction from the lower end of the first exit surface 22. The second reflecting surface 25 reflects the light incident on the first lens 2 from the first entrance 21 toward the first exit surface 22 side. Further, the second reflecting surface 25 reflects the light reflected by the first reflecting surface 24 toward the first exit surface 22 side.
[0019] The first exit surface 22 is formed on the right side of the first lens 2 in the drawing. The first exit surface 22 emits the light emitted from the light-emitting element 1, the light reflected by the first reflecting surface 24, and the light reflected by the second reflecting surface 25 as the first exit light to the second lens 3. Further, the first exit surface 22 is formed so that the curvature in the X direction and the curvature in the Y direction are different.
[0020] In the first lens 2, the light emitted from the light-emitting element 1 toward the lower side in the drawing is reflected by the second reflecting surface 25 and emitted from the first exit surface 22 toward the upper side in the drawing. Therefore, the light emitted from the first exit surface 22 toward the lower side in the drawing is cut off by the second reflecting surface 25.
[0021] Also, the light emitted from the light-emitting element 1 toward the upper side in the drawing is reflected by the first reflecting surface 24 toward the lower side in the drawing and then reflected by the second reflecting surface 25 toward the upper side in the drawing, so it is emitted from the first exit surface 22 toward the upper side in the drawing. Therefore, the first reflecting surface 24 and the second reflecting surface 25 can improve the optical efficiency of the lighting device.
[0022] The second lens 3 receives the first exit light emitted from the first lens 2 and emits the second exit light. The second lens 3 is an anamorphic lens with different curvatures in the Y direction and the X direction.
[0023] Specifically, the second lens 3 has a second incident surface 31, a second exit surface 32, and a second side surface portion 33 provided between the second incident surface 31 and the second exit surface 32.
[0024] The second incident surface 31 is formed on the left side of the drawing of the second lens 3 and is formed to be convex in the Z direction. The second incident surface 31 receives the first exit light emitted from the first exit surface 22 of the first lens 2.
[0025] The second exit surface 32 is formed on the right side of the drawing of the second lens 3 and is formed to be convex in the Z direction. The second exit surface 32 emits the light incident on the second lens 3 as the second exit light.
[0026] Also, there is a lens processing portion 34 below the drawing of the second lens 3 (the lower part of the second exit surface 32). The lens processing portion 34 is the portion where R is imparted on the second exit surface 32 when the second lens 3 is created by integral molding. When the light emitted from the first exit surface 22 of the first lens 2 enters the lens processing portion 34, it becomes stray light.
[0027] The diffusion plate 4 is a plate-like member formed to extend in the X and Y directions. The diffusion plate 4 receives the second exit light emitted from the second lens 3 and diffuses the second exit light in the X-axis direction. Specifically, the surface 41 on the second lens 3 side of the diffusion plate 4 is wavy. For this reason, when the second exit light enters the diffusion plate 4, it is diffused in the X direction by the surface 41 of the second lens 3.
[0028] FIG. 3 shows a side view of a conventional lighting device. In FIG. 3, since the first lens 2a is created by molding, the first exit surface 22a is concave. Also, the exit light R1 is the exit light when the first exit surface 22a is flat, and the exit light R2 is the actual exit light.
[0029] The emitted light R2, which is incident from the light-emitting element 1 to the first lens 2a and reflected by the first reflective surface 24, has its emission direction from the first emission surface 22a lower in the diagram than the emitted light R1 due to the concave lens effect of the first emission surface 22a. Furthermore, since the emitted light R2 is incident on the lens processing portion 34 of the second lens 3, it is emitted even further downward in the diagram than the emitted light R1. For this reason, the emitted light R2 becomes stray light.
[0030] Therefore, in Figure 1, the first lens 2 is manufactured such that its first emission surface 22 is convex.
[0031] As shown in Figure 1, the emitted light R3, which is incident from the light-emitting element 1 to the first lens 2 and reflected by the first reflective surface 24 of the first lens 2, is emitted from the first emission surface 22. At this time, since the first emission surface 22 is formed in a convex shape, it is refracted upwards in the drawing compared to the emitted light R2 in Figure 3. As a result, the emitted light R3 is incident on the second emission surface 32 so as not to be incident on the lens processing portion 34 of the second lens 3. In other words, by forming the first emission surface 22 in a convex shape, the emitted light R3 does not become stray light. Therefore, in a lighting device with a cutoff function, the generation of stray light can be suppressed while keeping costs down.
[0032] Here, we will explain the relationship between the first lens 2 and the second lens 3.
[0033] The first lens 2 and the second lens 3 are arranged such that at least one of the following equations (1) to (3) is satisfied.
[0034] 0.7 × F ≤ D ≤ 1.3 × F …(1) 0.9 × F ≤ D ≤ 1.1 × F …(2) 0.95 × F ≤ D ≤ 1.05 × F …(3) However, D is the distance from the principal plane S of the second lens 3 to the vertex p1 of the first emission surface 22 of the first lens 2, and F is the distance from the principal plane S of the second lens 3 to the focal point f of the second lens.
[0035] The principal plane S of the second lens 3 is a plane perpendicular to the Z direction (the direction in which the optical axis of the light-emitting element 1 extends), passing through the midpoint p4 between the vertex p2 of the second incident surface 31 of the second lens 3 and the vertex p3 of the second exit surface 32. The vertex p1 is the point on the first exit surface 22 closest to the second lens 3 in the Z direction. The vertex p2 is the point on the second incident surface 31 closest to the first lens 2 in the Z direction. The vertex p3 is the point on the second exit surface 32 furthest from the first lens 2 in the Z direction. The focal point f is the point where light incident on the second lens 3 from the diffuser plate 4 side along the Z direction converges.
[0036] In order for the lighting device to have high light distribution performance, it is preferable that it satisfies equation (1), more preferably equation (2), and even more preferably equation (3).
[0037] Furthermore, the first lens 2 is constructed to satisfy the following relationship.
[0038] 0.003 × L ≤ T …(4) However, L is the length in the Y direction at the first emission surface 22. Also, T is the distance in the Z direction from the edge of the first emission surface 22 (the point furthest from the second lens 3 in the Z direction) to the vertex p1. This makes it possible to suppress distortion of the first emission surface 22 when the first lens 2 is fabricated.
[0039] Furthermore, the first lens 2 and the second lens 3 are manufactured and positioned to satisfy the following equations (5) to (7).
[0040] T ≤ 0.1 × F …(5) T ≤ 0.05 × F …(6) T ≤ 0.02 × F …(7) This allows the lighting device to have advanced light distribution performance. In order for the lighting device to have advanced light distribution performance, it is preferable that equation (5) is satisfied, more preferably that equation (6) is satisfied, and even more preferably that equation (7) is satisfied.
[0041] (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 can be applied to embodiments that are modified, replaced, added, or omitted as appropriate.
[0042] In the above embodiment, the first lens 2 is created by a molding process in which it is formed using a mold, followed by a cooling process in which the first lens 2 is cooled. Here, the first emission surface 22 of the first lens 2 does not necessarily need to be formed in a convex shape during use; it is sufficient if it is formed in a convex shape during manufacturing (especially during the molding process). This prevents the first emission surface 22 of the first lens 2 from becoming concave, thereby preventing light from entering the lens processing portion 34 of the second lens 3, and thus achieving the above effect.
[0043] Furthermore, the diffusion plate 4 may not be provided in the above embodiment. [Industrial applicability]
[0044] The lighting device of the present invention can be applied to lighting devices having a cutoff function, such as vehicle headlights and floodlights installed on grounds. [Explanation of Symbols]
[0045] 1 Light-emitting element 2. First lens 3. Second lens 4. Diffuser 22 First launch area 31 2nd entrance plane 32 Second launch area 34 Lens Processing Section
Claims
1. Light-emitting element and A first lens receives light emitted from the light-emitting element at a first entrance and emits first emitted light, A second lens that receives the first emitted light and emits a second emitted light, Equipped with, The first lens has a first emission surface that emits the first emitted light, which is formed in a convex shape that protrudes in the direction of the optical axis of the light-emitting element. The first lens, when viewed from the side, is positioned such that the position of its maximum width in the vertical direction is closer to the first entrance opening than to the first exit surface. The illumination device is characterized in that the first lens extends from the opening end of the first entrance port, is not formed on the same plane as the first entrance port, and includes a first reflecting surface that reflects light incident on the first lens toward the first exit surface.
2. In the lighting device according to claim 1, The second lens is, The second incident surface that receives the first emitted light, It is provided at a position opposite to the second incident surface, and the second emission surface emits the second emitted light. Equipped with, An illumination device characterized in that the first lens and the second lens are arranged such that at least one of the following equations (1) to (3) is satisfied. 0.7 × F ≤ D ≤ 1.3 × F …(1) 0.9 × F ≤ D ≤ 1.1 × F …(2) 0.95 × F ≤ D ≤ 1.05 × F …(3) However, when the principal plane is defined as the plane passing through the midpoint between the vertex of the second incident surface and the vertex of the second exit surface and perpendicular to the optical axis direction, D is the distance from the vertex of the first exit surface to the principal plane, and F is the distance from the focal point of the second lens to the principal plane.
3. In the lighting device according to claim 1 or 2, The first lens is formed to satisfy the following equation (4), and the lighting device is characterized in that 0.003 × L ≤ T …(4) However, L is the vertical length of the first emission surface, and T is the distance from the edge to the vertex of the first emission surface in the optical axis direction.
4. In the lighting device according to any one of claims 1 to 3, The second lens is, The second incident surface that receives the first emitted light, It is provided at a position opposite to the second incident surface, and the second emission surface emits the second emitted light. Equipped with, An illumination device characterized in that the first lens and the second lens are arranged such that at least one of the following equations (5) to (7) is satisfied. T ≤ 0.1 × F …(5) T ≤ 0.05 × F …(6) T ≤ 0.02 × F …(7) However, T is the distance from the edge to the vertex of the first emission surface in the direction of the optical axis, and F is the distance from the focal point of the second lens to the principal plane, when the principal plane is defined as the plane passing through the midpoint between the vertex of the second incidence surface and the vertex of the second emission surface and perpendicular to the direction of the optical axis.
5. In the lighting device according to any one of claims 1 to 4, The illumination device is characterized in that the first emission surface is formed such that the curvature in the vertical direction when viewed from the optical axis direction is different from the curvature in the direction perpendicular to the vertical direction and the optical axis direction.
6. In the lighting device according to any one of claims 1 to 5, The illumination device is characterized in that the second lens is an anamorphic lens formed such that the curvature in the vertical direction when viewed from the optical axis direction is different from the curvature in the direction perpendicular to the vertical direction and the optical axis direction.
7. In the lighting device according to any one of claims 1 to 6, A lighting device characterized by further comprising a diffuser plate having a wave-shaped surface and receiving the second emitted light and diffusing the second emitted light.