Backlight wedge with side mounted light source

• US 20070274094A1
• Filed: 05/24/2006
• Published: 11/29/2007
• 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: Moskovich, Jacob, Meis, Michael A., Bryan, William J., Schultz, John C.
• Granted Patent: US 7,740,387 B2
• Time in Patent Office: Days
• US Class Current: 362/601
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side

Abstract

A backlight may include a light guide and a light input. The light guide may have a light reflection surface and a light emission surface. The light input may include a diverging wedge having a narrow end and opposing side surfaces extending to the narrow end. A light source may be disposed adjacent to one of the opposing side surfaces and may emit light into the light input portion. A multilayer polymeric mirror film may be disposed adjacent to the opposing side surfaces but not in intimate contact therewith and may reflect more than 95% of visible light incident on the multilayer polymeric mirror film.

Claims

1. A backlight comprising:

a visible light transmissive body primarily propagating light by TIR with an input and output surface, the visible light transmissive body having a light guide portion and a light input portion, the light guide portion having a light reflection surface and a light emission surface, the light input portion having opposing side surfaces that are not parallel;

a light source disposed adjacent to the input surface, the light source emitting light into the light input surface, the light input surface being one of the opposing side surfaces;

a multilayer polymeric mirror film disposed adjacent to the opposing side surfaces but not in intimate contact with the opposing side surfaces and reflecting more than 95% of visible light incident on the multilayer polymeric mirror film.

2. 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.

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

4. A backlight according to claim 1 wherein the light source comprises a plurality of light emitting diodes.

5. A backlight according to claim 1 wherein the light source comprises a plurality of light sources emitting red, blue and green light.

6. A backlight according to claim 5 wherein the light source further comprises a plurality of light sources emitting cyan, yellow or magenta light.

7. A backlight according to claim 1 wherein the multilayer polymeric mirror film reflects more than 98% of visible light incident at any angle on the multilayer polymeric mirror film.

8. A backlight according to claim 1 further comprising a liquid crystal display panel disposed adjacent to the light emission surface.

9. A backlight according to claim 1 wherein the light source is optically coupled to the light input portion.

10. A backlight according to claim 1, wherein the light source extends through the multilayer polymeric mirror film.

11. A backlight comprising:

a 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 light source disposed adjacent to one of the opposing side surfaces, the light source emitting light into 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

multilayer polymeric mirror film disposed adjacent to the opposing side surfaces but not in intimate contact with the opposing side surfaces, the multilayer polymeric mirror film reflecting more than 95% of visible light incident on the multilayer polymeric mirror film.

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

13. A backlight according to claim 11 wherein the light emission surface and the light reflection surface are non-parallel.

14. A backlight comprising:

a first 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 light source disposed adjacent to one of the first opposing side surfaces, the first light source emitting light into the first diverging wedge;

a second 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 light source disposed adjacent to the one of the second opposing side surfaces, the second light source emitting light into the second 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

multilayer polymeric mirror film disposed adjacent to the first and second opposing side surfaces but not in intimate contact with the first and second opposing side surfaces, the multilayer polymeric mirror film reflecting more than 95% of light incident on the multilayer polymeric mirror film.

15. A backlight according to claim 14 wherein the first light source comprises a plurality of light emitting diodes and the second light source comprises a plurality of light emitting diodes.

16. A backlight according to claim 14 wherein the first light source comprises a plurality of light sources emitting red, blue and green light and the second light source comprises a plurality of light sources emitting red, blue and green light.

17. A backlight according to claim 14 wherein the multilayer polymeric mirror film reflects more than 98% of visible light incident at all angles on the multilayer polymeric mirror film.

18. A backlight according to claim 14 wherein the light emission surface and the light reflection surface are parallel, and the light reflection surface comprises a plurality of light extraction elements.

19. A backlight according to claim 14 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 one of the third opposing side surfaces, the third light source emitting light into 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 but not in intimate contact with the third opposing side surfaces, the multilayer polymeric mirror film reflecting more than 95% of light incident on the multilayer polymeric mirror film.

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