Backlight wedge with adjacent reflective surfaces

• US 20070274095A1
• 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: Destain, Patrick R.
• Granted Patent: US 7,607,814 B2
• Time in Patent Office: Days
• US Class Current: 362/609
• 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 6/0055 Reflecting element, sheet or layer

Abstract

A backlight includes a visible light transmissive body having a light guide portion and a light input portion. The visible light transmissive body primarily propagates light by TIR and includes a light input surface and a light output surface. 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. A light source is disposed adjacent to the light input surface and emits light into the light input portion. A specularly reflective layer is disposed adjacent to but not in intimate contact with the opposing side surfaces and reflects more than 80% of visible light incident on the specularly reflective layer.

Claims

1. A backlight comprising:

a visible light transmissive body primarily propagating light by TIR with a light input surface and a light output surface and 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 light input surface, the light source emitting light into the light input portion;

a specularly reflective layer or film disposed adjacent to the opposing side surfaces but not in intimate contact with the opposing side surfaces and reflecting more than 80% of visible light incident on specularly reflective layer or 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 red light emitting, blue light emitting, and green light emitting light sources.

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

7. A backlight according to claim 1 wherein the specularly reflective layer is a multilayer polymeric mirror film reflecting more than 95% 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 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 the narrow end surface, the 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

a specularly reflective film disposed adjacent to the opposing side surfaces but not in intimate contact with the opposing side surfaces, reflecting more than 80% of visible light incident on specularly reflective film.

11. A backlight according to claim 10 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 10 wherein the light emission surface and the light reflection surface are non-parallel.

13. 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 the first narrow end surface, the first light source emitting light into the first narrow end surface of 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 second narrow end surface, the second light source emitting light into the second narrow end surface of 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

a specularly reflective film disposed adjacent to the opposing side surfaces but not in intimate contact with the opposing side surfaces, reflecting more than 80% of visible light incident on specularly reflective film.

14. A backlight according to claim 13 wherein the first light source comprises a plurality of light emitting diodes and the second light source comprises a plurality of light emitting diodes.

15. A backlight according to claim 13 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.

16. A backlight according to claim 13 further comprising an air gap disposed between the multilayer polymeric mirror film and each first and second opposing side surfaces.

17. A backlight according to claim 13 wherein the specularly reflective layer is a multilayer polymeric mirror film reflecting more than 95% of visible light incident at all angles on the multilayer polymeric mirror film.

18. A backlight according to claim 13 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 13 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

specularly reflective layer disposed adjacent to but not in intimate contact with the third opposing side surfaces, the specularly reflective layer reflecting more than 95% of light incident on the specularly reflective layer.

20. A backlight according to claim 13 further comprising a liquid crystal display panel disposed adjacent to the light emission surface.

21. A backlight comprising:

a visible light transmissive body primarily propagating light by TIR with an input and output surface having a light guide portion and a light input portion, the light guide portion having a light reflection surface and a light emission surface, with 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;

a specularly reflective layer or film disposed adjacent to the opposing side surfaces but not in intimate contact with the opposing side surfaces and reflecting more than 80% of visible light incident on the specularly reflective layer or film.