Backlight asymmetric light input wedge

• US 7,660,509 B2
• Filed: 05/24/2006
• Issued: 02/09/2010
• Est. Priority Date: 05/24/2006
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Meis, Michael A., Bryan, William J., Schultz, John C., Destain, Patrick R.
• Primary Examiner(s): Le; Uyen Chau N
• Assistant Examiner(s): Bedtelyon; John M
• Application Number:
  US11/439,764
• Publication Number:
  US 20070279931A1
• Time in Patent Office: 1,357 Days
• Field of Search: 349/65, 349/67, 385/129, 385/146, 362/608, 362/609, 362/610, 362/615, 362/621, 362/622, 362/628
• US Class Current: 385/146
• CPC Class Codes: G02B 6/0028 Light guide, e.g. taper
• CPC Class Codes: G02B 6/0031 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0043 provided on the surface of the light guide
• CPC Class Codes: G02B 6/0046 Tapered light guide, e.g. wedge-shaped light guide
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer

Abstract

A backlight is disclosed and includes a visible light transmissive body primarily propagating light by TIR with a light input surface and a light output surface and a light guide portion and a light input portion. The light guide portion has a light reflection surface and a light emission surface. The light input portion has opposing side surfaces that are not parallel. One of the opposing surfaces is co-planar with either the light emission surface or the light reflection surface. A light source is disposed adjacent to the light input surface. The light source emits light into the light input portion. A reflective layer is disposed adjacent to or on the opposing side surfaces.

Claims

1. A backlight comprising:

an asymmetric diverging wedge defined by a narrow end surface and a wide end surface, and opposing side surfaces that are not parallel and extend between the narrow end and the wide end;

a solid state light source extending into the asymmetric diverging wedge at the narrow end surface, the solid state light source emitting light into the narrow end surface of the diverging wedge;

a light guide optically coupled to the wide end surface, the light guide having a light reflection surface and a light emission surface, and one of the opposing side surfaces being co-planar from the narrow end surface to the wide end surface with either the light emission surface or the light reflection surface; and

a reflective layer disposed parallel with and adjacent to or on each of the opposing side surfaces.

2. A backlight according to claim 1 wherein the reflective layer is a multilayer polymeric mirror film disposed adjacent to the opposing side surfaces, the multilayer polymeric mirror film reflecting more than 95% of visible light incident on the multilayer polymeric mirror film.

3. A backlight according to claim 1 wherein the light emission surface and the light reflection surface are parallel, and the light reflection surface comprises a plurality of light extraction elements.

4. A backlight according to claim 1 wherein the light emission surface and the light reflection surface are non-parallel.

5. A backlight according to claim 2 wherein one opposing side surface of the asymmetric diverging wedge is co-planar with the emission surface.

6. A backlight according to claim 3 further comprising an air gap disposed between the specularly reflective layer and each first and second opposing side surfaces.

7. A backlight comprising:

a first asymmetric diverging wedge defined by a first narrow end surface and a first wide end surface, and first opposing side surfaces that are not parallel and extend between the first narrow end and the first wide end;

a first solid state light source extending into the first asymmetric diverging wedge at the first narrow end surface, the first solid state light source emitting light into the first narrow end surface of the first asymmetric diverging wedge;

a second asymmetric diverging wedge defined by a second narrow end surface and a second wide end surface, and second opposing side surfaces that are not parallel and extend between the second narrow end and the second wide end;

a second solid state light source extending into the second asymmetric diverging wedge at the second narrow end surface, the second solid state light source emitting light into the second narrow end surface of the second asymmetric diverging wedge;

a light guide optically coupled to the first wide end surface and the second wide end surface, the light guide having a light reflection surface and a light emission surface, and one of the first and second opposing side surfaces being co-planar from the narrow end surface to the wide end surface with either the light emission surface or the light reflection surface; and

a reflective layer disposed parallel with and adjacent to or on each of the opposing side surfaces.

8. A backlight according to claim 7 wherein the reflective layer is a multilayer polymeric mirror film disposed adjacent to the opposing side surfaces, the multilayer polymeric mirror film reflecting more than 95% of visible light incident on the multilayer polymeric mirror film.

9. A backlight according to claim 7 wherein the first solid state light source comprises a plurality of solid state light sources emitting red, blue and green light and the second solid state light source comprises a plurality of solid state light sources emitting red, blue and green light.

10. A backlight according to claim 8 further comprising an air gap disposed between the multilayer polymeric mirror film and each first and second opposing side surfaces.

11. A backlight according to claim 7 wherein the light emission surface and the light reflection surface are parallel, and the light reflection surface comprises a plurality of light extraction elements.

12. A backlight according to claim 7 wherein the light emission surface and the light reflection surface are non-parallel.

13. A backlight according to claim 7 further comprising a third diverging wedge defined by a third narrow end surface and a third wide end surface, and third opposing side surfaces that are not parallel and extend between the third narrow end and the third wide end;

a third light source disposed adjacent to the third narrow end surface, the third light source emitting light into the third narrow end surface of the third diverging wedge;

the light guide optically coupled to the third wide end surface; and

multilayer polymeric mirror film disposed adjacent to the third opposing side surfaces, the multilayer polymeric mirror film reflecting more than 95% of light incident on the multilayer polymeric mirror film.

14. A backlight according to claim 7 further comprising a liquid crystal display panel disposed adjacent to the light emission surface.