Illumination device and light-guiding member

Patent metadata

Field	Value
Publication number	US-10180529-B2
Application number	US-201414206062-A
Country	US
Kind code	B2
Filing date	Mar 12, 2014
Priority date	Mar 26, 2013
Publication date	Jan 15, 2019
Grant date	Jan 15, 2019

Abstract

In one embodiment, an illumination device includes a light-guiding unit having a light output surface which outputs light and a back surface facing the light output surface, wherein the light-guiding unit has a curved surface in a region of the back surface farther than a first position on the back surface that is away by a first distance from an axis passing the light output surface and the back surface, and a rough surface in a region of the light output surface farther than a second position on the light output surface that is away by a second distance from the axis in a same direction as a direction from the axis toward the first position, and where an intersection of the axis and the back surface is an origin point, and a direction of the axis from the back surface to the light output surface is positive, a normal line of the curved surface intersects with the axis at the positive side of the axis, and an angle formed by a normal line vector at the second position in a direction toward the light output surface from the back surface of the light output surface and a vector in a direction from the curved surface to the second position is equal to or more than a critical angle.

First claim

What is claimed is:

1. An illumination device comprising a point light source and a light-guiding unit,
wherein the light-guiding unit is disc-shaped and is rotationally symmetrical about an axis, and the point light source is disposed in a central portion the light-guiding unit,
wherein the light-guiding unit has a light output surface, a back surface, a curved surface, and a rough surface that is angled relative to the axis,
wherein the back surface has a first position that is away by a first distance from the axis,
wherein the light output surface has a second position that is away by a second distance from the axis,
wherein the curved surface is disposed at an outer periphery of the back surface,
wherein an intersection of the axis and the back surface is an origin point, a direction of the axis from the back surface to the light output surface is positive, a normal line of the curved surface intersects with the axis at a positive side of the axis, and an angle formed by a normal line vector in a direction toward the light output surface from the back surface and a vector in a direction from the curved surface to the second position is equal to or more than a critical angle,
wherein the rough surface is in a region of the light output surface farther than the second position on the light output surface, and light that is totally reflected off the curved surface is diffused and transmitted through the rough surface,
wherein light sources are arranged with a regular interval in a ring shape manner, and
wherein the light-guiding unit comprises:
a rough end surface connecting with the back surface in a region of the light output surface farther than the second position, and a normal line of the end surface and a normal line of the back surface intersect each other at a negative side of the axis, and
scatter dots provided on the back surface in order to scatter guided light, a distribution of the scatter dots being rarefactional when the scatter dots are closer to the axis and condensational when the scatter dots are farther from the axis
wherein the back surface comprises a flat surface portion extending from a third position on the back surface to the first position; and wherein the light output surface comprises a flat surface portion extending from a fourth position on the light output surface to the second position, and wherein the flat surface portion of the light output surface is substantially parallel to the flat surface portion of the back surface.

2. The illumination device according to claim 1 , wherein
the light-guiding unit has a hollow hole whose center is at the axis, and
the light source is arranged in the hollow hole, and emits the light toward a side surface of the hollow hole.

3. The illumination device according to claim 1 ,
wherein the scatter dots of the light-guiding unit form scatter units for scattering incident light, and
wherein a coverage factor ρ(r) of the scatter units at a distance r from the axis satisfies a following expression,

ρ
⁡

(
r
)

=

α
⁢

r

β
-

r
2

where the first distance is denoted as r E , α is a positive real number, and β is a real number satisfying β≥αr E +r E 2 .

4. The illumination device according to claim 3 , wherein the coverage factor ρ(r) of the scatter units at the distance r from the axis satisfies a following expression,

ρ
⁡

(
r
)

=

ρ
⁡

(

r
S

)

⁢

C

2
⁢

⁢

r
S

⁢

2
⁢

⁢
r

C
+

r
S
2

-

r
2

where the first distance is denoted as r E , and a distance from the axis to a side surface of a hollow hole of the light-guiding unit is denoted as r s ,
and ρ(r s ) satisfies

ρ
⁡

(

r
S

)

≤

r
S

r
E

and C is a constant that satisfies

C
≥

r
S

r
S

-

r
E

⁢

ρ
⁡

(

r
S

)

⁢

(

r
E
2

-

r
S
2

)

.

5. The illumination device according to claim 4 , wherein the scatter units are in a circular shape having a diameter D, and where a pitch P 1 of a radial direction of the scatter units is consta

Assignees

• Toshiba Kk

Inventors

• Ohno Hiroshi
• Yamamoto Yuichiro
• Kato Mitsuaki
• Takamatsu Tomonao
• Shiratsuchi Masataka
• Hayashihara Hiromichi
• Tamura Hideo
• Yamamoto Masahiko

Classifications

• F21V2200/20

  of light guides of a generally planar shape · CPC title

• G02B6/0046

  Tapered light guide, e.g. wedge-shaped light guide · CPC title

• G02B6/0036

  2-D arrangement of prisms, protrusions, indentations or roughened surfaces · CPC title

• F21K9/20

  Light sources comprising attachment means · CPC title

• G02B6/0085

  Means for removing heat created by the light source from the package · CPC title