Luminaire

Abstract

To narrow down a light distribution angle.SOLUTION: A luminaire includes: a light source 10 capable of emitting light; and a collimator lens 12 which includes an incident surface 14 of light and an emission surface 16 of the light, and which includes an outside surface 28 which is in the periphery of the incident surface 14 and the emission surface 16 and which can reflect part of the light internally. The collimator lens 12 includes a concave part 18 opposing to the light source 10. An inner surface of the concave part 18 includes a bottom surface 24 smaller than an opening 22, and includes an inside surface 26 tapered toward the bottom surface 24 with a shape in which a straight line inclined at an angle of 10 degrees or more and 20 degrees or less with respect to an optical axis A of the light rotates around the optical axis A . Light enters the bottom surface 24 only at a light distribution angle of within 3 degrees with respect to the optical axis A, and enters the inside surface 26 at the light distribution angle of exceeding 3 degrees with respect to the optical axis A. Emission light from the emission surface 16 includes incident light from the bottom surface 24 and reflection light on the outside surface 28. The reflection light is the light from the inside surface 26.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a lighting device. [Background technology]

[0002] In lighting devices, light with a narrow light distribution angle (ideally parallel light) is sometimes required (Patent Document 1). A collimator lens can be used to obtain parallel light (Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-88326 A [Patent Document 2] JP 2015-60631 A Summary of the Invention [Problem to be solved by the invention]

[0004] Collimator lenses, which have a light refracting surface and a light reflecting surface, have limitations on how large the curvature of the refracting surface can be, making it difficult to obtain a narrow light distribution angle.

[0005] An object of the present invention is to narrow the light distribution angle. [Means for solving the problem]

[0006] The lighting device includes a light source capable of emitting light, and a collimator lens including an incident surface for the light and an exit surface for the light, and including an outer surface around the incident surface and the exit surface capable of internally reflecting a portion of the light, wherein the collimator lens has a recess facing the light source, and an inner surface of the recess includes a bottom surface that is smaller than an opening, and includes an inner surface that is tapered toward the bottom surface in a shape formed by rotating a straight line inclined at an angle of 10 degrees or more and 20 degrees or less with respect to an optical axis of the light around the optical axis, wherein the light is incident on the bottom surface only at a light distribution angle of 3 degrees or less with respect to the optical axis, and is incident on the inner surface at a light distribution angle of more than 3 degrees with respect to the optical axis, and the light emitted from the exit surface includes light incident from the bottom surface and light reflected at the outer surface, and the reflected light is light from the inner surface.

[0007] Since little light is incident on the bottom surface of the recess, a lot of light can be reflected on the outer surface, thereby narrowing the light distribution angle. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic cross-sectional view of a lighting device according to an embodiment. [Diagram 2] FIG. 4 is a luminance distribution diagram of the lighting device according to the embodiment. [Diagram 3] FIG. 2 is a diagram showing an illuminance distribution of the lighting device according to the embodiment. [Figure 4] FIG. 11 is a schematic cross-sectional view of a lighting device according to a modified example of the embodiment. [Diagram 5] 1 is a schematic cross-sectional view of a lighting device according to an application example of an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. However, the present invention can be embodied in various forms without departing from the spirit of the present invention, and the present invention should not be interpreted as being limited to the description of the embodiment exemplified below.

[0010] In order to clarify the description, the drawings may show the width, thickness, shape, etc. of each part in a schematic manner compared to the actual embodiment, but these are merely examples and do not limit the interpretation of the present invention. In this specification and each drawing, elements having the same functions as those explained in the previous drawings may be given the same reference numerals, and duplicate explanations may be omitted.

[0011] Furthermore, in the detailed description of the present invention, when defining the positional relationship between a certain component and another component, "above" and "below" do not only mean a component being located directly above or below another component, but also include a component being located between the other components, unless otherwise specified.

[0012] 1 is a schematic cross-sectional view of a lighting device according to an embodiment. The lighting device has a light source 10 (e.g., a light-emitting diode or a filament). The light source 10 can emit light (e.g., white light) that spreads from an optical axis A (the central axis of a light beam). The light distribution angle of the light is less than 180 degrees (e.g., 120 degrees to 130 degrees).

[0013] The illumination device has a collimator lens 12. The collimator lens 12 is made of transparent resin or optical glass. The collimator lens 12 includes an entrance surface 14 and an exit surface 16 for light.

[0014] The collimator lens 12 has a recess 18 facing the light source 10. All of the light from the light source 10 is incident on the inner surface of the recess 18. The inner surface of the recess 18 is the light incidence surface 14. The light source 10 is outside the recess 18. The collimator lens 12 has a flat rear surface 20 that extends around the recess 18 in a direction perpendicular to the optical axis A. The opening 22 of the recess 18 is circular.

[0015] The inner surface of the recess 18 includes a bottom surface 24 that is smaller than the opening 22. The bottom surface 24 is a flat surface perpendicular to the optical axis A. Light is incident on the bottom surface 24 only at a light distribution angle of 3 degrees or less with respect to the optical axis A. The bottom surface 24 is a part of the light incident surface 14.

[0016] The inner surface of the recess 18 includes an inner surface 26. The inner surface 26 is tapered toward the bottom surface 24. The inner surface 26 has a shape in which a straight line inclined at an angle of 10 degrees or more and 20 degrees or less with respect to the optical axis A of the light is rotated around the optical axis A. The inner surface 26 is another part of the light incident surface 14 (e.g., all except the bottom surface 24). The light is incident on the inner surface 26 at a light distribution angle of more than 3 degrees with respect to the optical axis A. The incident light is refracted at the inner surface 26.

[0017] The collimator lens 12 includes an outer surface 28. The outer surface 28 is located around the incident surface 14. The outer surface 28 is capable of internally reflecting a portion of the light (light refracted at the inner surface 26). The outer surface 28 is a curved surface that is convex in the opposite direction to the optical axis A. The curved surface has a shape in which a curve rotates around the optical axis A. The curved surface is shaped so that the light that is refracted at the inner surface 26 and comes directly therefrom is reflected parallel to the optical axis A toward the exit surface 16. The outer surface 28 may be covered with a light-reflecting film.

[0018] The light exit surface 16 is a flat surface perpendicular to the optical axis A. The exit surface 16 is circular. The opening 22 of the recess 18 is less than one-fifth the diameter of the exit surface 16. An outer surface 28 lies around the periphery of the exit surface 16. The light emitted from the exit surface 16 includes light incident from the bottom surface 24 and light reflected at the outer surface 28. The reflected light is light reflected from the inner surface 26.

[0019] 2 is a luminance distribution diagram of the lighting device according to the embodiment, which shows that there is almost no light at a zenith angle exceeding ±20 degrees.

[0020] 3 is a diagram showing the illuminance distribution of the lighting device according to the embodiment, which shows that the spread of light is generally within ±200 mm.

[0021] In this embodiment, since not much light is incident on the bottom surface 24 of the recess 18, a lot of light can be reflected by the outer surface 28, thereby making it possible to narrow the light distribution angle.

[0022] 4 is a schematic cross-sectional view of an illumination device according to a modified example of the embodiment. In this modified example, the bottom surface 124 of the recess 118 of the collimator lens 112 is substantially a point. As a result, only light that is approximately parallel to the optical axis A of the light source 110 is incident on the bottom surface 124.

[0023] FIG. 5 is a schematic cross-sectional view of an illumination device according to an application example of the embodiment. The illumination device has a lens panel 30 in addition to a light source 10 and a collimator lens 12. The lens panel 30 has a pair of transparent substrates 32. A polymer-dispersed liquid crystal layer 34 is interposed between the pair of transparent substrates 32. The liquid crystal layer 34 is between a first electrode 36 and a second electrode 38. The first electrode 36 and the second electrode 38 are transparent. When no voltage is applied between the first electrode 36 and the second electrode 38, the light travels straight through the liquid crystal layer 34 and the traveling direction of the light does not change. In contrast, when a voltage is applied between the first electrode 36 and the second electrode 38, the light is scattered in the liquid crystal layer 34. In this way, the light distribution angle of the light can be adjusted.

[0024] The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, the configurations described in the embodiments can be replaced with substantially the same configurations, configurations that provide the same effects, or configurations that can achieve the same purpose. [Explanation of symbols]

[0025] 10 light source, 12 collimator lens, 14 incident surface, 16 exit surface, 18 recess, 20 rear surface, 22 opening, 24 bottom surface, 26 inner surface, 28 outer surface, 30 lens panel, 32 transparent substrate, 34 liquid crystal layer, 36 first electrode, 38 second electrode, 110 light source, 112 collimator lens, 118 recess, 124 bottom surface, A optical axis.

Claims

1. A light source capable of emitting light; a collimator lens including an incident surface and an exit surface of the light, the collimator lens including an outer surface around the incident surface and the exit surface capable of internally reflecting a portion of the light; having the collimator lens has a recess facing the light source, the inner surface of the recess includes a bottom surface that is smaller than the opening, and includes an inner surface that is tapered toward the bottom surface in a shape obtained by rotating a straight line that is inclined at an angle of 10 degrees or more and 20 degrees or less with respect to an optical axis of the light around the optical axis, the light is incident on the bottom surface only at a light distribution angle of 3 degrees or less relative to the optical axis, and is incident on the inner surface only at a light distribution angle of more than 3 degrees relative to the optical axis; the light emitted from the light exit surface includes light incident from the bottom surface and light reflected at the outer surface, The lighting device, wherein the reflected light is light from the inner surface.

2. 2. The lighting device according to claim 1, The bottom surface is a flat surface perpendicular to the optical axis.

3. 2. The lighting device according to claim 1, The illumination device, wherein the light exit surface is a flat surface perpendicular to the optical axis.

4. 2. The lighting device according to claim 1, An illumination device in which all of the light from the light source is incident on the inner surface of the recess.

5. 2. The lighting device according to claim 1, the light source is outside the recess; The illumination device, wherein the light distribution angle of the light is less than 180 degrees.

6. 2. The lighting device according to claim 1, the outer surface is a curved surface that is convex in a direction opposite to the optical axis, The curved surface has a shape obtained by rotating a curve around the optical axis.

7. 2. The lighting device according to claim 1, The collimator lens has a flat rear surface that extends around the recess in a direction perpendicular to the optical axis.

8. 2. The lighting device according to claim 1, the exit surface and the opening are circular; An illumination device wherein the aperture is less than or equal to one-fifth the diameter of the exit surface.

9. 2. The lighting device according to claim 1, The collimator lens is made of transparent resin or optical glass.

10. 2. The lighting device according to claim 1, The light source is a light emitting diode or a filament.

Images