Luminaire

Abstract

To make a light distribution angle narrow.SOLUTION: An incidence surface 14 is an inner surface of a concave part 18 opposed to a light source 10. The inner surface of the concave part 18 includes a bottom face 24 and an inner side face 26. The inner side face 26 has a shape in which a free curve protruded in an inward direction of the concave part 18 is rotated around an optical axis A of light. A tangent passing through one point of the free curve has a smaller angle to the optical axis A as the one point is closer to the bottom face 24 and a larger angle to the optical axis A as the one point is farther away from the bottom face 24, a curvature of the free curve is not constant, and a point where the curvature is maximum is at a depth wich is 1 / 3 or less of a depth of the concave part 18. Light is made incident on the bottom face 24 at only a light distribution angle within 3 degrees to the optical axis A and also is made incident on the inner side face 26 at an angle of light distribution exceeding three degrees to the optical axis A, wherein the incident light to the bottom face 24 exits from an emission surface 16, and the incident light to the inner side face 26 is reflected by an outer side face 28 to exit from the emission surface 16.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). Conversely, Patent Document 3 discloses a lens for obtaining a desired light distribution angle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-88326 A [Patent Document 2] JP 2015-60631 A [Patent Document 3] JP 2016-33886 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 illumination device includes a light source capable of emitting light, and a collimator lens including an entrance surface for the light and an exit surface for the light, and including an outer surface around the entrance surface and the exit surface capable of internally reflecting the light, the entrance surface being an inner surface of a recess facing the light source, the inner surface of the recess including a bottom surface and an inner surface, the inner surface having a shape obtained by rotating a free curve that is convex toward the inside of the recess around an optical axis of the light, and a tangent passing through a point on the free curve becomes smaller the closer the point is to the bottom surface. the angle between the optical axis is small, and the farther the point is from the bottom surface, the larger the angle between the optical axis is, the curvature of the free curve is not constant, and the point at which the curvature is maximum is at a depth of 1 / 3 or less of the depth of the recess, 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, the light incident on the bottom surface exits from the exit surface, and the light incident on the inner surface is reflected by the outer surface and exits from the exit surface. [Brief description of the drawings]

[0007] [Figure 1] 1 is a schematic cross-sectional view of a lighting device according to an embodiment. [Diagram 2] FIG. 1 is a schematic cross-sectional view of a lighting device according to a related art. [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

[0008] 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 construed as being limited to the description of the embodiment exemplified below.

[0009] 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.

[0010] 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.

[0011] 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).

[0012] 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.

[0013] 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.

[0014] 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.

[0015] 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 is another part of the light incident surface 14 (e.g., all of it except for the bottom surface 24). 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. Not much light is incident on the bottom surface 24, and more light is incident on the inner surface. The light that is incident on the inner surface 26 is refracted at the inner surface 26.

[0016] The inner surface 26 has a shape in which a free curve that is convex toward the inside of the recess 18 is rotated around the optical axis A of light. The angle between a tangent line passing through a point on the free curve and the optical axis A becomes smaller the closer the point is to the bottom surface 24. In other words, the inner surface 26 is upright in a portion closer to the bottom surface 24. The angle between a tangent line passing through a point on the free curve and the optical axis A becomes larger the farther the point is from the bottom surface 24. In other words, the inner surface 26 is largely inclined in a portion farther from the bottom surface 24. The curvature of the free curve is not constant. The point at which the curvature is maximum is located at a depth from the rear surface 20 that is 1 / 3 or less of the depth D of the recess 18.

[0017] The collimator lens 12 includes an outer surface 28. The outer surface 28 is located around the incident surface 14. Light incident on the inner surface 26 is reflected by the outer surface 28. The outer surface 28 is capable of internally reflecting a portion of the light (light refracted by 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 has a shape that reflects the light that is refracted by the inner surface 26 and comes directly toward the exit surface 16 in a direction parallel to the optical axis A. The outer surface 28 may be covered with a light-reflecting film. The light reflected by the outer surface 28 exits from the exit surface 16.

[0018] Light incident on bottom surface 24 exits from exit surface 16. Light exit surface 16 is a flat surface perpendicular to optical axis A. Exit surface 16 is circular. In diameter, opening 22 of recess 18 is less than one-fifth the size of exit surface 16. Outer surface 28 lies around exit surface 16. Light exiting from exit surface 16 includes light incident from bottom surface 24 and light reflected at outer surface 28. The reflected light is light from inner surface 26.

[0019] 2 is a schematic cross-sectional view of a lighting device according to a related art. Here, the inner surface 102 has a shape in which a straight line inclined at an angle of 10 degrees to 20 degrees with respect to the optical axis A of the light is rotated around the optical axis A. Light refracted near the bottom surface 108 of the inner surface 102 having such a shape proceeds to the exit surface 106, not to the outer surface 104, and is refracted at the exit surface 106 before being emitted. As a result, the light spreads.

[0020] 1, in this embodiment, the angle between the inner surface 26 and the optical axis A is small when the inner surface 26 is closer to the bottom surface 24, so the refracted light is directed toward the outer surface 28. This makes it possible to suppress the spread of light and narrow the light distribution angle. On the other hand, the angle between the inner surface 26 and the optical axis A is large when the inner surface 26 is farther from the bottom surface 24, so the height along the optical axis A is smaller. This makes it possible to reduce the thickness of the collimator lens 12.

[0021] 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.

[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 enters the bottom surface 124 and exits from the exit surface with almost no refraction.

[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.

[0025] [Overview of the embodiment] (1) A collimator lens 12 includes a light source 10 capable of emitting light, and an incident surface 14 for the light and an exit surface 16 for the light, and includes an outer surface 28 around the incident surface 14 and the exit surface 16 capable of internally reflecting the light, wherein the incident surface 14 is an inner surface of a recess 18 facing the light source 10, the inner surface of the recess 18 includes a bottom surface 24 and an inner surface 26, the inner surface 26 has a shape in which a free curve that is convex toward the inside of the recess 18 is rotated around the optical axis A of the light, and a tangent passing through a point on the free curve is such that the point is close to the bottom surface 24. the angle between the optical axis A is smaller, and the angle between the optical axis A is larger, the curvature of the free curve is not constant, and the point at which the curvature is maximum is at a depth of 1 / 3 or less of the depth of the recess 18, the 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 and 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 light incident on the bottom surface 24 exits from the exit surface 16, and the light incident on the inner surface 26 is reflected by the outer surface 28 and exits from the exit surface 16.

[0026] The angle between the inner surface 26 and the optical axis A is small when the inner surface 26 is closer to the bottom surface 24, so the refracted light is directed toward the outer surface 28. This makes it possible to suppress the spread of light and narrow the light distribution angle. Also, the angle between the inner surface 26 and the optical axis A is large when the inner surface 26 is farther from the bottom surface 24, so the height along the optical axis A can be reduced. This makes it possible to reduce the thickness of the collimator lens.

[0027] (2) The lighting device according to (1), wherein the bottom surface 24 is a flat surface perpendicular to the optical axis A.

[0028] (3) The lighting device according to (1) or (2), wherein the exit surface 16 is a flat surface perpendicular to the optical axis A.

[0029] (4) The lighting device according to any one of (1) to (3), wherein all of the light from the light source 10 is incident on the inner surface of the recess 18.

[0030] (5) The lighting device according to any one of (1) to (4), wherein the light source 10 is located outside the recess 18, and the light distribution angle of the light is less than 180 degrees.

[0031] (6) An illumination device according to any one of (1) to (5), wherein the outer surface 28 is a curved surface that is convex in the opposite direction to the optical axis A, and the curved surface has a shape in which a curve is rotated around the optical axis A.

[0032] (7) An illumination device according to any one of (1) to (6), wherein the collimator lens 12 has a flat rear surface 20 extending around the recess 18 in a direction perpendicular to the optical axis A.

[0033] (8) The lighting device according to any one of (1) to (7), wherein the light exit surface 16 and the opening 22 are circular, and the diameter of the opening 22 is less than one-fifth of the light exit surface 16.

[0034] (9) The illumination device according to any one of (1) to (8), wherein the collimator lens 12 is made of transparent resin or optical glass.

[0035] (10) The lighting device according to any one of (1) to (9), wherein the light source 10 is a light-emitting diode or a filament. [Explanation of symbols]

[0036] 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, 102 inner surface, 104 outer surface, 106 exit surface, 108 bottom surface, 110 light source, 112 collimator lens, 118 recess, 124 bottom surface, 180 light distribution angle, A optical axis, D depth.

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 the light; having the light incidence surface is an inner surface of a recess facing the light source, The inner surface of the recess includes a bottom surface and an inner side surface, the inner surface has a shape obtained by rotating a free curve that is convex toward the inside of the recess around an optical axis of the light, a tangent line passing through a point of the free curve has a smaller angle with the optical axis as the point is closer to the bottom surface, and a larger angle with the optical axis as the point is farther from the bottom surface; The curvature of the free curve is not constant, the point of maximum curvature is at a depth equal to or less than 1 / 3 of the depth of the recess; 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; Light incident on the bottom surface is emitted from the exit surface, An illumination device in which light incident on the inner surface is reflected by the outer surface and exits from the exit 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. 10. The lighting device according to claim 1 , The light source is a light emitting diode or a filament.

Images