Ring-shaped light emitting unit

• US 20060139946A1
• Filed: 12/09/2005
• Published: 06/29/2006
• Est. Priority Date: 12/24/2004
• Status: Active Grant

• Current Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Original Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Inventors: Tamaki, Makoto
• Granted Patent: US 7,147,356 B2
• Time in Patent Office: Days
• US Class Current: 362/602
• CPC Class Codes: G02B 6/0018 Redirecting means on the surface of the light guide
• CPC Class Codes: G02B 6/0046 Tapered light guide, e.g. wedge-shaped light guide

Abstract

A ring-shaped light emitting unit comprising a ring-shaped light guiding member having a light emitting surface which continues in a direction in which the ring-shaped light guiding unit extends, and a light guiding path for introducing light of a light source into the ring-shaped light guiding member which is continuously connected to part of an outer circumference of the ring-shaped light guiding member, wherein the outer circumference of the ring-shaped light guiding member excluding a light inlet portion is truly round. In addition, an inner circumference of the ring-shaped light guiding member is also truly round. A center of the inner circumference of the ring-shaped light guiding member is located closer to an open end of the light guiding path than a center of the outer circumference of the ring-shaped light guiding member.

Claims

1. A ring-shaped light emitting unit comprising:

a ring-shaped light guiding member having a light emitting surface which continues in a direction in which the ring-shaped light guiding device extends; and

a light guiding path for introducing light of a light source into the ring-shaped light guiding member connected to part of an outer circumference of the ring-shaped light guiding member,

wherein the outer circumference, excluding a light inlet portion, of the ring-shaped light guiding member and an inner circumference thereof are truly round when viewed from the top, and

wherein a center of the inner circumference of the ring-shaped light guiding member is located closer to an open end of the light guiding path than a center of the outer circumference of the ring-shaped light guiding member.

2. The ring-shaped light emitting unit according to claim 1, wherein a distance between the center of the outer circumference of the ring-shaped light guiding member and the center of the inner circumference thereof is 2% to 10% per 100% of a diameter of the inner circumference thereof.

3. The ring-shaped light emitting unit according to claim 1, wherein a distance between the center of the outer circumference of the ring-shaped light guiding member and the center of the inner circumference thereof is 0.5% to 8% per 100% of a diameter of the outer circumference thereof.

4. The ring-shaped light emitting unit according to claim 1, wherein a center axis of the light guiding path is in parallel with a center axis of the ring-shaped light guiding member in the vicinity of the light inlet portion.

5. The ring-shaped light emitting device according to claim 1, wherein a center axis of the light guiding path is superposed on a center axis of the ring-shaped light guiding member in the vicinity of the light inlet portion.

6. The ring-shaped light emitting unit according to claim 1, wherein an imaginary straight line which connects the center of the outer circumference of the ring-shaped light guiding member with the center of the inner circumference thereof is substantially in parallel with the center axis of the light guiding path.

7. The ring-shaped light emitting unit according to claim 1, wherein the light guiding path comprises a light guiding member which is formed from the same material as that of the ring-shaped light guiding member.

8. The ring-shaped light emitting unit according to claim 1, wherein the ring-shaped light guiding member and the light guiding path are formed integrally with each other.

9. The ring-shaped light emitting unit according to claim 1, wherein the light source comprises an LED.

10. The ring-shaped light emitting unit according to claim 1, wherein the ring-shaped light guiding path is continuously connected to a part of the ring-shaped light guiding member.

11. The ring-shaped light emitting unit according to claim 1, wherein the light inlet portion connects the ring-shaped light guiding member and the light guiding path.

12. The ring-shaped light emitting unit according to claim 1, wherein an inclined surface is formed on an inner surface side of the ring-shaped light guiding member.

13. The ring-shaped light emitting unit according to claim 12, wherein the inclined surface comprises a reflection surface for reflecting an introduced light.