Light diffusing apparatus with U-shaped light guide

• US 5,581,683 A
• Filed: 02/09/1995
• Issued: 12/03/1996
• Est. Priority Date: 04/07/1994
• Status: Expired due to Fees

• Current Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Original Assignee: Northern Telecom Limited (Nortel Networks Corporation)
• Inventors: Koens, Paul J., Bertignoll, Friedrich
• Primary Examiner(s): Lee, John D.
• Application Number:
  US08/385,844
• Time in Patent Office: 663 Days
• Field of Search: 385/31-36, 385/38, 385/123, 385/129, 385/133, 385/139, 385/140, 385/146, 385/147, 385/901, 385/902, 362/32
• US Class Current: 385/146
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: G02B 6/0003 the light guides being doped with fluorescent agents
• CPC Class Codes: G02B 6/0016 Grooves, prisms, gratings, scattering particles or rough surfaces
• CPC Class Codes: G02B 6/0028 Light guide, e.g. taper
• CPC Class Codes: G02B 6/0041 provided in the bulk of the light guide
• CPC Class Codes: G02B 6/241 Light guide terminations
• CPC Class Codes: G09F 9/305 being the ends of optical fibres G09F9/302 takes precedence
• CPC Class Codes: Y10S 385/901 Illuminating or display apparatus

Abstract

A light diffusing apparatus, which may be used as an elongate visual indicator in telephone sets, video cassette recorders etc, provides very even illumination (i.e., evenly diffused light without any discernible bright spots) when illuminated by spot light from one or two light emitting diodes. The apparatus includes a light guide having a light path of sufficient length to disperse the spot light from the emitting diodes. The dispersed light from the light guide then passes through a light diffuser. The light output end of the light guide and the light input surface of the light diffuser have uniform texture surfaces to further diffuse the dispersed light. The light diffuser may include diffusing particles. Very even illumination without any discernible bright spots is provided.

Claims

1. Apparatus for providing substantially evenly diffused light from light radially emitted by a light source, comprising:

a substantially U-shaped light guide having first and second end surfaces which are spaced apart from each other at opposite ends of the U-shaped light guide so as to face from the light guide in substantially the same direction, the first end surface facing the light source to receive the radially emitted light with the second end surface being elongate,

said light guide having sufficient length between the first and second end surfaces to disperse the radially emitted light, while the light is transmitted around the U-shade of the guide from the first end surface to the second end surface, to provide substantially dispersed light across the entire second end surface; and

a light diffuser having opposed elongate light input and output surfaces, the light input surface being adjacent to and extending along the second end surface, the second end surface of the light guide and the light input surface of the light diffuser provided at a light transfer region to transfer the substantially dispersed light from the light guide to the light diffuser, at least one of the surfaces of the light transfer region having a uniform texture to further disperse the dispersed light, and the light diffuser capable of diffusing the dispersed light transferred through the light transfer region substantially evenly across the light output surface of the light diffuser.

2. Apparatus according to claim 1, wherein the light input surface of the light diffuser has uniform texture to diffuse the substantially dispersed light.

3. Apparatus according to claim 1, wherein the second end surface of the light guide has uniform texture.

4. Apparatus according to claim 1 or 3, wherein the light diffuser includes diffusing particles therein.

5. Apparatus according to claim 4, wherein the light diffusing particles are of plastic material.

6. Apparatus according to claim 1 wherein the light guide is substantially rectangular in cross-section with two major side surfaces and is in U-shape with a major side surface of one end region opposing a major side surface of the other end region of the light guide.

7. Apparatus according to claim 1, wherein the light source comprises two light emitting devices, the distance between which being about a half of the elongate length of the first end surface, the two light emitting devices being centered about the center of the first end surface.

8. Apparatus for providing substantially evenly diffused light from light radially emitted by a light source, comprising:

a substantially U-shaped light guide having first and second end surfaces which are spaced apart from each other at opposite ends of the U-shaped light guide so as to face from the light guide in substantially the same direction, the first end surface facing the light source to receive the radially emitted light with the second end surface being elongate;

said light guide having sufficient length between the first and second end surfaces to disperse the radially emitted light, while the light is transmitted around the U-shape of the light guide from the first end surface to the second end surface, to provide substantially dispersed light across the entire second end surface; and

a light diffuser having opposed light input and output surfaces, the light input surface being adjacent to and extending along the second surface for the light input surface to receive the substantially dispersed light;

said light diffuser including light diffusing particles distributed therein to effect diffusion of the dispersed light substantially evenly across the light output surface.

9. Apparatus according to claim 8, wherein the diffusing particles are plastic material.

10. Apparatus according to claim 8, wherein the light input surface of the light diffuser is bonded to the second end surface of the light guide.

11. Apparatus according to claim 8, wherein the light source comprises two light emitting devices, the distance between which being about a half of the elongate length of the first end surface, the two light emitting devices being centered about the center of the first end surface.

12. Apparatus for providing substantially evenly diffused light from light radially emitted by a light source, comprising a substantially U-shaped light guide having first and second end surfaces which are spaced apart from each other at opposite ends of the U-shaped light guide, the first end surface facing the light source to receive the radially emitted light with the second end surface being elongate, the light guide having a first end region extending from the first end surface and a second end region extending from the first end region to the second end surface, the first end region being of sufficient length to provide substantially dispersed light, the light guide including diffusing particles distributed therein at the second end region for diffusing the dispersed light substantially evenly across the second end surface of the light guide.

13. Apparatus according to claim 12, wherein the diffusing particles are plastic material.

14. Apparatus according to claim 12, wherein the light source comprises two light emitting devices, the distance between which being about a half of the elongate length of the first end surface, the two light emitting devices being centered about the center of the first end surface.

15. A telephone base housing an apparatus for providing substantially evenly diffused light from spot light generated by a light source, the apparatus comprising:

a substantially U-shaped light guide having first and second end surfaces which are spaced apart from each other at opposite ends of the U-shaped light guide so as to face from the light guide in substantially the same direction, the first end surface facing the light source to receive the emitted light with the second end surface being elongate,

said light guide having sufficient length between the first and second end surfaces to disperse the emitted light, while the light is transmitted around the U-shape of the guide from the first end surface to the second end surface, to provide substantially dispersed light across the entire second end surface; and

a light diffuser having opposed elongate light input and output surfaces, the light input surface being adjacent to and extending along the second end surface, the second end surface of the light guide and the light input surface of the light diffuser provided at a light transfer region to transfer the substantially dispersed light from the light guide to the light diffuser, at least one of the surfaces of the light transfer region having a uniform texture to further disperse the dispersed light, and the light diffuser capable of diffusing the dispersed light transferred through the light transfer region substantially evenly across the light output surface of the light diffuser.

16. A telephone base according to claim 15 wherein the light guide is substantially rectangular in cross section.