Lighting device, lighting device manufacturing method, and light distributor
A lighting device includes a light source and a light distributor disposed on a light emission side of the light source. The light distributor includes an entrance surface through which light enters and an exit surface through which the light that enters through the entrance surface exits. At least one of the entrance surface and the exit surface includes concave regions. Each of the concave regions includes a smooth concave surface. The concave regions control distribution of light from the light source that is refracted or reflected by an optical lens or a reflective component.
1. A lighting device, comprising:
a light source; and
a light distributor disposed on a light emission side of the light source, wherein
the light distributor includes an entrance surface through which light enters and an exit surface through which the light that enters through the entrance surface exits,
at least one of the entrance surface and the exit surface includes concave regions, each of the concave regions including a smooth concave surface,
the concave regions control distribution of light from the light source that is one of refracted and reflected by an optical component,
the optical component includes a reflective component and an optical lens,
an outer diameter of the light distributor is approximately equal to an outer diameter of the optical lens, and
the light distributor is approximately parallel to the optical lens.
2. The lighting device according to claim 1 , wherein
in a cross section of each concave region of the concave regions taken substantially parallel to an optical axis of the light source, the concave region:
has an approximate arc shape; and
satisfies the following expression:
0.05 ≤d≤ 5
where d is a distance in millimeters from a perimeter of the concave region to a line that is perpendicular to the at least one of the entrance surface and the exit surface that includes the concave region and passes through a center point that defines the approximate arc shape.
3. The lighting device according to claim 1 , wherein
in a cross section of each concave region of the concave regions taken substantially parallel to an optical axis of the light source, the concave region:
has an approximate arc shape; and
satisfies the following expression:
0.05 ≤d≤ 0.5
where d is a distance in millimeters from a perimeter of the concave region to a line that is perpendicular to the at least one of the entrance surface and the exit surface that includes the concave region and passes through a center point that defines the approximate arc shape.
4. The lighting device according to claim 1 , wherein
in a cross section of each concave region of the concave regions taken substantially parallel to an optical axis of the light source, the concave region:
has an approximate arc shape; and
satisfies the following expression:
10
°
<
arctan
(
2
dD
(
d
2
-
D
2
)
)
<
50
°
where d is a distance from a perimeter of the concave region to a line that is perpendicular to the at least one of the entrance surface and the exit surface that includes the concave region and passes through a center point that defines the approximate arc shape, and
D is a depth of the concave region.
5. The lighting device according to claim 1 , wherein
in a cross section of each concave region of the concave regions taken substantially parallel to an optical axis of the light source, the concave region:
has an approximate arc shape; and
satisfies the following equation:
α
=
arctan
(
2
dD
(
d
2
-
D
2
)
)
where d is a distance from a perimeter of the concave region to a first line that is perpendicular to the at least one of the entrance surface and the exit surface that includes the concave region and passes through a center point that defines the approximate arc shape,
D is a depth of the concave region, and
α is an acute angle between a second line that connects the center point and the perimeter of the concave region and the first line.
6. The lighting device according to claim 5 , wherein
each of the concave regions has an approximate ellipse shape in a plan view, and
the acute angle along the major axis of the approximate ellipse shape is larger than the acute angle along the minor axis of the approximate ellipse shape by at least 10 degrees.
7. The lighting device according to claim 5 , wherein
α is in a range from 10 degrees to 50 degrees, inclusive, and
a light usage efficiency of the light distributor is at least 0.9.
8. The lighting device according to claim 1 , wherein
in a plan view taken substantially parallel to an optical axis of the light source, the concave regions:
each have an approximate circle shape, and
satisfy the following equation:
T
=
(
A
B
)
where A is a dot diameter of each of the concave regions,
B is an inter-dot distance between two of the concave regions that are adjacent, and
T is a dot superimposition rate between two of the concave regions that are adjacent, and is at least 50% and at most 250%.
9. The lighting device according to claim 1 , wherein
the reflective component of the optical component reflects light from the light source, and
the reflective component has a reflectivity of at least 70%.
10. The lighting device according to claim 1 , wherein
the light distributor is attachable to and detachable from the lighting device.
11. The lighting device according to claim 1 , wherein
the concave regions are arranged in a matrix in the entrance surface, and each of the concave regions is an approximate semispherical recess.
12. The lighting device according to claim 1 , wherein
in a plan view taken substantially parallel to an optical axis of the light source, each of the concave regions has an approximate circle shape.
13. The lighting device according to claim 12 , wherein
in a cross section of each concave region of the concave regions taken substantially parallel to the optical axis of the light source, the concave region satisfies the following expression:
0.05 ≤d≤ 5,
where d is a radius in millimeters of the approximate circle shape of the concave region measured on the at least one of the entrance surface and the exit surface that includes the concave region.
14. The lighting device according to claim 12 , wherein
each of the concave regions is approximately semispherical and defined by a sphere, and
a distance between centers of two adjacent ones of the concave regions is less than a diameter of the sphere which defines the two adjacent ones of the concave regions.
15. The lighting device according to claim 1 , wherein
a circumferential edge of each of the light distributor and the optical lens includes a plurality of recesses, and
a circumferential edge of the reflective component includes a plurality of projections which are configured to project into the plurality of recesses of each of the light distributor and the optical lens.
16. A method of manufacturing the lighting device according to claim 1 , the method comprising:
forming the concave regions that each include the smooth concave surface, by emitting laser light onto a workpiece and scanning a focus point of the laser light.
17. The method according to claim 16 , wherein
in a plan view taken substantially parallel to an optical axis of the light source, the concave regions:
each have an approximate circle shape, and
satisfy the following equation:
T
=
(
A
B
)
where A is a dot diameter of each of the concave regions,
B is an inter-dot distance between two of the concave regions that are adjacent, expressed as, in the emitting of the laser light, a scanning speed of the laser light divided by a frequency of the laser light, and
T is a dot superimposition rate between two of the concave regions that are adjacent, and is at least 50% and at most 250%.
18. The lighting device according to claim 1 , wherein the optical lens transmits and controls distribution of incident light from the reflective component.
19. A lighting device comprising:
a light source; and
a light distributor disposed on a light emission side of the light source,
wherein the light distributor includes an entrance surface through which light enters and an exit surface through which the light that enters through the entrance surface exits,
at least one of the entrance surface and the exit surface includes concave regions, each of the concave regions including a smooth concave surface,
the concave regions control distribution of light from the light source that is one of refracted and reflected by an optical component, and
an arithmetical mean roughness of the smooth concave surface is at most 0.4 μm.
20. A light distributor disposed on a light emission side of a light source, the light distributor comprising:
an entrance surface through which light from the light source enters;
an exit surface through which the light that enters through the entrance surface exits; and
concave regions dispersed in at least one of the entrance surface and the exit surface, each of the concave regions including a smooth concave surface, wherein
the concave regions control distribution of the light from the light source that is one of refracted and reflected by an optical component,
the optical component includes a reflective component and an optical lens,
an outer diameter of the light distributor is approximately equal to an outer diameter of the optical lens, and
the light distributor is approximately parallel to the optical lens.