Illuminating device
The lighting device addresses stray light and cost issues by using a convex first lens and anamorphic second lens with reflective surfaces to enhance optical efficiency and reduce manufacturing complexity.
Patent Information
- Application Number
- JP2024194844
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-11-07
- Publication Date
- 2025-01-24
- Estimated Expiration
- 2039-09-25
AI Technical Summary
Existing lighting devices with a cutoff function face issues such as stray light due to concave exit surfaces on lenses, which increase manufacturing costs and reduce optical efficiency, and require multiple molds for processing.
The lighting device employs a first lens with a convex exit surface and a second lens with anamorphic curvature, combined with reflective surfaces to control light direction and reduce stray light, while minimizing manufacturing costs.
This configuration effectively suppresses stray light emission and enhances optical efficiency while maintaining cost-effectiveness by avoiding concave lens effects and reducing the need for multiple molds.
Smart Images
Figure 2025013553000001_ABST
Abstract
Description
[Technical field]
[0001] The present invention relates to a lighting device having a cut-off function. [Background technology]
[0002] Conventionally, there have been lighting devices equipped with a cut-off function. For example, in floodlights used on outdoor grounds, the light emitted in a predetermined direction is cut off so that the 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 light incident on the upper part of the first lens downward, cutting off light incident on the upper part of the second lens. In addition, 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 entrance part of the second lens is formed in a convex shape, it is possible to reduce light incident on the side wall (side surface part) of the second lens. In this way, Patent Document 1 prevents stray light and a decrease in optical efficiency. [Prior art documents] [Patent documents]
[0004] [Patent Document 1] JP 2018-206600 A Summary of the Invention [Problem to be solved by the invention]
[0005] However, when the first lens in Patent Document 1 is manufactured by molding, sink marks are likely to occur on the exit 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 exit surface of the first lens is likely to become concave.
[0006] Furthermore, when the second lens is produced by molding using a metal mold, a processing R is imparted to the upper part of the exit surface. By producing the side portion and the exit surface portion of the second lens separately, the processing R can be suppressed, but this requires the production of multiple metal molds, which significantly increases costs.
[0007] When the emission surface of the first lens is concave and the emission surface of the second lens has an R pattern on the upper part, the light incident on the emission surface of the first lens from the light emitting element is refracted upward at the emission surface of the first lens due to the concave lens effect of the first lens, and is further refracted upward at the emission surface of the second lens due to the R pattern formed on the emission surface of the second lens. As a result, light is irradiated upward from the emission surface of the second lens, generating stray light.
[0008] An object of the present invention is to provide a lighting device having a cut-off function that can suppress the generation of stray light while keeping costs down. [Means for solving the problem]
[0009] In order to achieve the above object, an illumination device according to one embodiment of the present invention includes 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 emission surface that emits the first emitted light and is formed in a convex shape that protrudes in the optical axis direction of the light-emitting element. [Brief description of the drawings]
[0010] [Figure 1] FIG. 2 is a side view of the lighting device according to the embodiment. [Diagram 2] FIG. 4 is a plan view of a second lens and a diffusion plate according to the embodiment. [Diagram 3] FIG. 1 is a side view of a conventional lighting device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0011] Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings. The following description of the preferred embodiments is merely illustrative in nature and is not intended to limit the present invention, its application, or its uses.
[0012] FIG. 1 shows a side view of the lighting device according to this embodiment, and FIG. 2 shows a plan view of the second lens and the diffusion plate according to this embodiment. As shown in FIG. 1, this lighting device includes a light-emitting element 1, a first lens 2, a second lens 3, and a diffusion plate 4. In the following description, the Z direction indicates the direction in which the optical axis of the light-emitting element 1 extends, the Y direction indicates the up-down direction, and the X direction indicates the direction perpendicular to the Y direction and the Z direction. The first lens 2, the second lens 3, and the diffusion plate 4 are each made of a transparent resin. The first lens 2, the second lens 3, and the diffusion plate 4 are made of, for example, polypropylene, polyethylene, polyethylene terephthalate, polyvinyl chloride, ABS resin, acrylic, polyamide, polycarbonate, Teflon (registered trademark), or the like.
[0013] The light emitting element 1 is constituted by 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 a first emitted light to the second lens 3. Specifically, the first lens 2 has a first entrance 21, a first exit surface 22, and a first side portion 23 provided between the first entrance 21 and the first exit surface 22.
[0015] The first incident aperture 21 is formed on the left side of the first lens 2 in the figure, and is formed in a concave shape so as to surround the light emitting element 1. The first incident aperture 21 receives the light emitted from the light emitting element 1.
[0016] The first side surface portion 23 includes a first reflecting surface 24 and a second reflecting surface 25.
[0017] First reflecting surface 24 is formed so as to spread out diagonally upward to the right in the drawing and in the X direction from the upper end of the opening of first incident port 21. First reflecting surface 24 reflects light that has entered first lens 2 from first incident port 21 toward first exit surface 22 or second reflecting surface 25.
[0018] Second reflecting surface 25 is formed so as to spread out diagonally downward to the left in the drawing and in the X direction from the lower end of first exit surface 22. Second reflecting surface 25 reflects light incident on first lens 2 from first entrance 21 toward first exit surface 22. Second reflecting surface 25 also reflects light reflected by first reflecting surface 24 toward first exit surface 22.
[0019] First exit surface 22 is formed on the right side of first lens 2 in the drawing. First exit surface 22 emits, as first exit light, the light emitted from light-emitting element 1, the light reflected by first reflecting surface 24, and the light reflected by second reflecting surface 25 to second lens 3. First exit surface 22 is formed so that its curvature in the X direction is different from its curvature in the Y direction.
[0020] In the first lens 2, the light emitted from the light-emitting element 1 toward the lower side of the drawing is reflected by the second reflecting surface 25 and emitted toward the upper side of the drawing from the first exit surface 22. Therefore, the second reflecting surface 25 cuts off the light emitted from the first exit surface 22 toward the lower side of the drawing.
[0021] Furthermore, light emitted from the light-emitting element 1 toward the upper side of the drawing is reflected toward the lower side of the drawing by the first reflecting surface 24 and toward the upper side of the drawing by the second reflecting surface 25, and is therefore emitted toward the upper side of the drawing from the first exit surface 22. Therefore, the first reflecting surface 24 and the second reflecting surface 25 can increase the optical efficiency of the lighting device.
[0022] The second lens 3 receives the first outgoing light emitted from the first lens 2 and emits a second outgoing light. The second lens 3 is an anamorphic lens having different curvatures in the Y direction and the X direction.
[0023] Specifically, the second lens 3 has a second entrance surface 31 , a second exit surface 32 , and a second side surface portion 33 provided between the second entrance surface 31 and the second exit surface 32 .
[0024] The second incident surface 31 is formed on the left side of the second lens 3 in the figure, and is formed to be convex in the Z direction. The second incident surface 31 receives the first outgoing 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 second lens 3 in the drawing, and is formed so as to be convex in the Z direction. The second exit surface 32 emits the light incident on the second lens 3 as a second exit light.
[0026] Further, the second lens 3 has a lens processed portion 34 on the lower side in the drawing (below the second exit surface 32). When the second lens 3 is produced by integral molding, the lens processed portion 34 is a portion to which R is imparted on the second exit surface 32. When the light emitted from the first exit surface 22 of the first lens 2 enters the lens processed 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 outgoing light emitted from the second lens 3, and diffuses the second outgoing light in the X-axis direction. Specifically, the diffusion plate 4 has a wave-shaped surface 41 on the second lens 3 side. Therefore, when the second outgoing 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, the first lens 2a is produced by molding, so 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 outgoing light R2, which is incident on the first lens 2a from the light-emitting element 1 and reflected by the first reflecting surface 24, is emitted from the first outgoing surface 22a in a direction lower in the drawing than the outgoing light R1 due to the concave lens effect of the first outgoing surface 22a. Furthermore, since the outgoing light R2 is incident on the lens processed portion 34 of the second lens 3, it is emitted further downward in the drawing than the outgoing light R1. For this reason, the outgoing light R2 becomes stray light.
[0030] Therefore, in FIG. 1, the first lens 2 is produced so that the first exit surface 22 of the first lens 2 is convex.
[0031] As shown in FIG. 1, the emitted light R3, which is incident on the first lens 2 from the light-emitting element 1 and reflected by the first reflecting 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, the emitted light R3 is refracted toward the upper side of the drawing more than the emitted light R2 in FIG. 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 having a cut-off function, it is possible to suppress the generation of stray light while suppressing costs.
[0032] Here, the relationship between the first lens 2 and the second lens 3 will be described.
[0033] The first lens 2 and the second lens 3 are disposed so as to satisfy at least one of the following formulas (1) to (3).
[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) Here, D is the distance from the principal plane S of the second lens 3 to the vertex p1 of the first exit 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 that passes through a midpoint p4 between a vertex p2 of the second entrance surface 31 of the second lens 3 and a vertex p3 of the second exit surface 32, and is perpendicular to the Z direction (the direction in which the optical axis of the light-emitting element 1 extends). The vertex p1 is the closest point in the Z direction from the second lens 3 on the first exit surface 22. The vertex p2 is the closest point in the Z direction from the first lens 2 on the second entrance surface 31. The vertex p3 is the farthest point in the Z direction from the first lens 2 on the second exit surface 32. The focal point f is a point where the light that is incident on the second lens 3 from the diffuser plate 4 side along the Z direction is concentrated.
[0036] In order to provide a lighting device with a high level of light distribution performance, it is preferable to satisfy formula (1), it is more preferable to satisfy formula (2), and it is even more preferable to satisfy formula (3).
[0037] Moreover, the first lens 2 is manufactured so as to satisfy the following relationship.
[0038] 0.003×L≦T …(4) Here, L is the length in the Y direction of first exit surface 22. Furthermore, T is the distance in the Z direction from the end of first exit surface 22 (the point farthest from second lens 3 in the Z direction) to vertex p1. This makes it possible to suppress distortion of first exit surface 22 when first lens 2 is produced.
[0039] Moreover, the first lens 2 and the second lens 3 are created and disposed so as to satisfy the following expressions (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 a higher level of light distribution performance. In order to provide the lighting device with a higher level of light distribution performance, it is preferable to satisfy formula (5), it is more preferable to satisfy formula (6), and it is even more preferable to satisfy formula (7).
[0041] (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 may be applied to embodiments in which modifications, substitutions, additions, omissions, etc. are made as appropriate.
[0042] In the above embodiment, the first lens 2 is produced through a molding process in which the lens is molded using a mold or the like, followed by a cooling process in which the lens 2 is cooled. Here, the first exit surface 22 of the first lens 2 does not necessarily need to be formed in a convex shape when in use, but only needs to be formed in a convex shape during manufacture (particularly during the molding process). This makes it possible to prevent the first exit surface 22 of the first lens 2 from becoming concave, thereby preventing light from entering the lens processed portion 34 of the second lens 3, and thus obtaining the above-mentioned effect.
[0043] In the above embodiment, the diffusion plate 4 does not necessarily have to be provided. [Industrial Applicability]
[0044] The lighting device of the present invention can be applied to lighting devices having a cut-off function, such as vehicle headlights and floodlights installed on the ground. [Explanation of symbols]
[0045] 1 Light emitting element 2 First lens 3 Second lens 4 Diffuser 22 First exit surface 31 Second entrance plane 32 Second exit surface 34 Lens Processing Department
Claims
1. A light-emitting element; a first lens that receives light emitted from the light emitting element and emits a 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 from which the first emitted light is emitted, the first emission surface being formed in a convex shape protruding in an optical axis direction of the light-emitting element.
2. 2. The lighting device according to claim 1, The second lens is a second incident surface that receives the first emitted light; a second exit surface that is provided at a position opposite to the second entrance surface and that emits the second exit light; Equipped with An illumination device, characterized in that the first lens and the second lens are arranged so as to satisfy at least one of the following expressions (1) to (3). 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 a plane that passes through the midpoint between the vertex of the second entrance surface and the vertex of the second exit surface and is 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 focus of the second lens to the principal plane.
3. 3. The lighting device according to claim 1, The illumination device, wherein the first lens is formed so as to satisfy the following formula (4): 0.003 × L ≦ T ... (4) Here, L is the length of the first exit surface in the vertical direction, and T is the distance from the end of the first exit surface to the vertex in the optical axis direction.
4. The lighting device according to any one of claims 1 to 3, An illumination device, characterized in that the first lens and the second lens are arranged so as to satisfy at least one of the following expressions (5) to (7). T ≦ 0.1 × F ... (5) T ≦ 0.05 × F ... (6) T ≦ 0.02 × F ... (7) Here, T is the distance from the end of the first exit surface to the vertex in the optical axis direction, and F is the distance from the focus of the second lens to the principal plane, when the principal plane is a plane that passes through the midpoint between the vertex of the second entrance surface and the vertex of the second exit surface and is perpendicular to the optical axis direction.
5. The lighting device according to any one of claims 1 to 4, A lighting device characterized in that the first exit surface is formed so that its curvature in the up-down direction when viewed from the optical axis direction is different from its curvature in the up-down direction and in a direction perpendicular to the optical axis direction.
6. The lighting device according to any one of claims 1 to 5, The second lens is an anamorphic lens formed so that its curvature in the up-down direction when viewed from the optical axis direction is different from its curvature in the up-down direction and in a direction perpendicular to the optical axis direction.
7. The lighting device according to any one of claims 1 to 6, 13. An illumination device, comprising: a diffusion plate having a wave-shaped surface, receiving the second outgoing light and diffusing the second outgoing light.
8. 1. A method for manufacturing a first lens used in an illumination device including a light emitting element, a first lens, and a second lens, comprising: a molding step of molding the first lens; and a cooling step of cooling the molded first lens, a first exit surface of the first lens, which emits a first exit light, being formed to have a convex shape in an optical axis direction of the light-emitting element, in the molding step.
Citation Information
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