LIGHT EMITTING DEVICE AND OPTICAL ELEMENT

• US 20110299295A1
• Filed: 02/16/2010
• Published: 12/08/2011
• Est. Priority Date: 02/24/2009
• Status: Active Grant

• Current Assignee: Nittoh Kogaku Kabushiki Kaisha, Yasuhiro Koike
• Original Assignee: Nittoh Kogaku Kabushiki Kaisha, Yasuhiro Koike
• Inventors: Mochizuki, Keiichi
• Granted Patent: US 8,727,591 B2
• Time in Patent Office: Days
• US Class Current: 362/558
• CPC Class Codes: G02B 6/001 the light being emitted along at least a portion of the lateral surface of the fibre
• CPC Class Codes: G02B 6/0038 Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width of the light guide
• CPC Class Codes: G02B 6/0061 to provide homogeneous light output intensity
• CPC Class Codes: H04N 1/02835 in combination with a light guide, e.g. optical fibre, glass plate light-guides per se G02B6/00
• CPC Class Codes: H04N 1/0289 Light diffusing elements, e.g. plates or filters optical diffusing elements per se G02B5/02
• CPC Class Codes: H04N 2201/0081 Image reader H04N2201/0091 - H04N2201/0094 take precedence

Abstract

Disclosed are a light emitting device and a light emitting element that can decrease fabrication difficulties, while improving lighting efficiency and controlling the distribution of intensity that occurs in the emitted light. A light emitting device comprises a rod-shaped light guide, an LED that inputs light to the light guide, and a prism that changes the direction of light input from the lengthwise end of the light guide, and emits redirected light from a light exit surface that is disposed opposite the prism. The light emitting device is constituted so that an input lens is formed at the lengthwise end of the light guide as a parallel light forming body to make light exiting from the LED toward the light guide nearly parallel light, and the LED is shifted from the center axis of the light guide toward the side closer to the prism, or toward the side away from the prism, and thus said nearly parallel light is directed to the exit surface of the light guide or to the prism.

Claims

1. A light emitting device comprising:

a rod-shaped light guide;

a light source which inputs light to the light guide; and

a prism part which changes the direction of light input from the length-wise end of the light guide, and emits redirected light from a light exit surface that is disposed opposite the prism part;

in which;

a parallel light forming body, which makes light emitted from the light source toward the light guide nearly parallel light, is formed at the length-wise end of the light guide; and

the light source is shifted from the center axis of the light guide toward the side closer to the prism part, or toward the side away from the prism part, for the nearly parallel light to be directed to the light exit surface of the light guide or to the prism part.

2. The light emitting device according to claim 1:

in which the light source is tilted with respect to the center axis of the light guide.

3. The light emitting device according to claim 1:

in which the parallel light forming body is a convex lens that swells toward the light source.

4. The light emitting device according to claim 1:

further comprising a reflecting member which is placed around the light source and makes light which does not enter the light guide directly from the light source input to the light guide.

5. The light emitting device according to claim 1:

in which a light scattering guide, which contains light scattering particles for multiple-scattering the light emitted from the light source toward the light guide, is provided on the light exit surface of the light guide.

6. The light emitting device according to claim 1:

in which the prism part is placed in parallel with the light exit surface.

7. An optical element comprising:

a rod-shaped light guide; and

a prism part which changes the direction of light input from the length-wise end of the light guide, and emits redirected light from a light exit surface that is disposed opposite the prism part;

in which;

a parallel light forming body, which makes light emitted from a light source toward the light guide nearly parallel light, is formed at the length-wise end of the light guide.

8. The optical element according to claim 7:

in which a light scattering guide, which contains light scattering particles for multiple-scattering the light emitted from the light source toward the light guide, is provided on the light exit surface of the light guide.

9. The optical element according to claim 8:

in which the light scattering guide is rod-shaped; and

a surface of the light scattering guide, being opposite to another surface that faces the light guide, swells at a center part in a width-wise direction to form a convex-curved surface.

10. The optical element according to claim 8:

in which the light scattering guide is formed together with the light guide into a single piece.

11. The optical element according to claim 8:

in which the light scattering particles are translucent silicon particles with their particle diameter within a range from 2 to 9 micrometers.

12. The optical element according to claim 8:

in which the light scattering particles contained in the light scattering guide have turbidity expressed as “

τ

”

, which is a scattering parameter corresponding to a scattering coefficient of the light scattering guide, within a range of “

1<

T/τ

<

10”

, wherein T is a maximum thickness of the light scattering guide in a direction perpendicular to the light exit surface.

13. The optical element according to claim 7:

in which the light contains light scattering particles for multiple-scattering the input light.

14. The optical element according to claim 13:

in which the light scattering particles are translucent silicon particles with their particle diameter within a range from 2 to 9 micrometers.

15. The optical element according to claim 13:

in which the light scattering particles contained in the light guide have turbidity expressed as “

τ

”

, which is a scattering parameter corresponding to a scattering coefficient of the light guide, within a range of “

0<

L/(2×

τ

)<

30”

, wherein “

L”

is the length of the light guide in the center axis direction.