Surface light source device

• US 5,779,338 A
• Filed: 09/06/1996
• Issued: 07/14/1998
• Est. Priority Date: 08/12/1994
• Status: Expired due to Fees

• Current Assignee: Enplas Corporation
• Original Assignee: Enplas Corporation
• Inventors: Ishikawa, Tsuyoshi, Yokoyama, Kazuaki, Watai, Kayoko
• Primary Examiner(s): Husar, Stephen F.
• Application Number:
  US08/709,118
• Time in Patent Office: 676 Days
• Field of Search: 362/26, 362/27, 362/31
• US Class Current: 362/625
• CPC Class Codes: G02B 6/0025 Diffusing sheet or layer; Prismatic sheet or layer
• 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 6/0046 Tapered light guide, e.g. wedge-shaped light guide
• CPC Class Codes: G02B 6/0051 Diffusing sheet or layer
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0061 to provide homogeneous light output intensity
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources

Abstract

A surface light source device using a light conducting member, in which a multiplicity of concave portions are formed on an opposite surface of a light emitting surface of the light conducting member and the concave portions are arranged to have specific shapes to obtain a bright surface light source with a uniform brightness. A light diffusing material is fulfilled within the concave portions of the light conducting member so that a more uniform brightness can be obtained in an easy manner.

Claims

1. A surface light source device comprising a light conducting member made of transparent material, a linear light source disposed adjacent to one of edge surfaces of said light conducting member, and a diffusion plate disposed on a light emitting surface side of said light conducting member, said light conducting member comprising a multiplicity of concave portions formed on an opposite side surface of said light emitting surface of said light conducting member and a light diffusing material applied on all over the opposite side surface of the light conducting member.

2. A surface light source device according to claim 1, wherein each of said concave portion are arranged to be conical or polygonal pyramid shape.

3. A surface light source device according to claim 1, wherein said concave portions have the same shapes and the same dimensions but the pitches are arranged to be larger on a light source side and become smaller farther from said light source.

4. A surface light source device according to claim 1, wherein dimensions of said concave portions are smaller on a light source side and become larger farther from said light source.

5. A surface light source device according to claim 2, wherein depths of said conical or polygonal pyramid-shaped concave portions are the same and top angles thereof are smaller on a light source side and become larger as farther from said light source.

6. A surface light source device according to claim 2, wherein depths and top angles of said conical or polygonal pyramid-shaped concave portions are smaller on a light source side and become larger as farther from said light source.

7. A surface light source device according to claim 2, wherein top portions of said conical or polygonal pyramid-shaped concave portions are directed toward said light source.

8. A surface light source device comprising a light conducting member made of transparent material, a linear light source disposed adjacent to one of edge surfaces of said light conducting member, a diffusion plate disposed on a light emitting surface side of said light conducting member, and a reflective member disposed on an opposite side surface of said light emitting surface of said light conducting member, said light conducting member comprising a multiplicity of concave portions formed on said opposite side surface of the light conducting member and a light diffusing material or a light scattering material is provided in said concave portions.

9. A surface light source device according to claim 8, wherein each of said concave portions are of conical or polygonal pyramid shape.

10. A surface light source device according to claim 8, wherein said concave portions have the same shapes and the same dimensions but are spaced farther apart on a light source side and closer to each other away from said light source.

11. A surface light source device according to claim 8, wherein dimensions of said concave portions are smaller on a light source side and larger away from said light source.

12. A surface light source device according to claim 9, wherein depths of said conical or polygonal pyramid shaped concave portions are the same and top angles thereof are smaller on a light source side and larger away from said light source.

13. A surface light source device according to claim 9, wherein depths and top angles of said conical or polygonal pyramid-shaped concave portions are smaller on a light source side and larger away from said light source.

14. A surface light source device according to claim 9, wherein top portions of said conical or polygonal pyramid-shaped concave portions are directed toward said light source.