Backlight wedge with encapsulated light source

• US 7,317,182 B2
• Filed: 05/24/2006
• Issued: 01/08/2008
• Est. Priority Date: 05/24/2006
• Status: Expired due to Fees

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Meis, Michael A., Schultz, John C.
• Primary Examiner(s): Lee; John R.
• Application Number:
  US11/440,327
• Publication Number:
  US 20070272839A1
• Time in Patent Office: 594 Days
• Field of Search: 250/227.11, 250/227.28, 250/227.29, 250/227.31, 385/36, 385/146, 362/610, 362/612, 362/613, 362/624, 362/627, 362/628, 362/800
• US Class Current: 250/227.31
• 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 6/0068 Arrangements of plural sources, e.g. multi-colour light sources
• CPC Class Codes: G02B 6/009 of the light source in the package G02B6/0021 takes precedence

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 well may be formed in the light input, and a light source may be disposed within the light source well. An encapsulant may be disposed about the light source, within the light source well. A specularly reflective film or layer may be disposed adjacent to but not in intimate contact with the opposing side surfaces and may reflect more than 80% 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 having a light guide portion and a light input portion, the light guide portion having a light reflection surface and a light emission surface, and the light input portion having opposing side surfaces that are not parallel;

a light source well formed in one of the light input portion surfaces, the light source well including a light source well surface;

a light source extending into the light source well, the light source emitting light into the light input portion;

an encapsulant disposed between the light source and the light source well surface; and

a specularly reflective film or layer disposed adjacent to the opposing side surfaces, reflecting more than 80% of light, that is emitted from the light source and escapes through the opposing side surfaces, back into the visible light transmissive body.

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

3. A backlight according to claim 1 wherein the encapsulant comprises a primary encapsulant covering the light source and a secondary encapsulant disposed between the primary encapsulant and the light source well surface.

4. A backlight according to claim 3 wherein the primary encapsulant comprises a high modulus material.

5. A backlight according to claim 3 wherein the secondary encapsulant comprises a low modulus material.

6. A backlight according to claim 1 wherein the encapsulant optically couples the light source to the light input portion.

7. A backlight according to claim 1 wherein the light input portion comprises a narrow end surface, the light source well formed in the narrow end surface.

8. A backlight according to claim 1 wherein the light source well is formed in one of the opposing side surfaces.

9. A backlight according to claim 8 wherein the specularly reflective film or layer comprises multilayer polymeric mirror film reflecting more than 95% of visible light incident on the multilayer polymeric mirror film.

10. A backlight according to claim 9 wherein the multilayer polymeric mirror film reflects more than 98% of visible light incident on the multilayer polymeric mirror film.

11. A backlight according 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.

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

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

14. A backlight according to claim 1, wherein the light source well comprises a channel.

15. A backlight according to claim 1, wherein the light source well comprises a plurality of individual depressions.

16. A backlight comprising:

a diverging wedge primarily propagating light by TIR and 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 well formed in one of the wedge surfaces, the light source well including a light source well surface;

a light source extending into the light source well, the light source emitting light into the diverging wedge;

an encapsulant disposed between the light source and the light source well surface;

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 or layer disposed adjacent to the opposing side surfaces, reflecting more than 80% of light, that is emitted from the light source and escapes through the opposing side surfaces, back into the visible light transmissive body.

17. A backlight according to claim 16 wherein the light emission surface and the light reflection surface are parallel, and the light reflection surface comprises a plurality of light extraction elements.

18. A backlight according to claim 16 wherein the light emission surface and the light reflection surface are non-parallel.

19. A backlight comprising:

a first diverging wedge primarily propagating light by TIR and defined by a first narrow end surface and a first wide end surface, and first non-parallel opposing side surfaces that extend between the first narrow end and the first wide end;

a first light source well formed in one of the first diverging wedge surfaces, the first light source well including a first light source well surface;

a first light source extending into the first light source well, the first light source emitting light into the first diverging wedge;

a first encapsulant disposed between the first light source and the first light source well surface;

a second diverging wedge defined by a second narrow end surface and a second wide end surface, and second non-parallel opposing side surfaces that extend between die second narrow end and the second wide end;

a second light source well formed in one of the second diverging wedge surfaces, the second light source well including a second light source well surface;

a second light source extending into the second light source well, the second light source emitting light into the second diverging wedge;

a second encapsulant disposed between the second light source and the second light source well surface;

at 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 extraction surface; and

a specularly reflective film or layer disposed adjacent to the opposing side surfaces, reflecting more than 80% of light, that is emitted from the light source and escapes through the opposing side surfaces, back into the visible light transmissive body.

20. A backlight according to claim 19 wherein the light emission surface and the light reflection surface are parallel, and the light reflective surface comprises a plurality of light extraction elements.

21. A backlight according to claim 19 wherein the light emission surface and the light reflection surface are non-parallel.

22. A backlight assembly according to claim 19 wherein the first encapsulant optically couples the first light source to the first diverging wedge.

23. A backlight assembly according to claim 19 wherein the second encapsulant optically couples the second light source to the second diverging wedge.

24. A backlight assembly according to claim 19 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 well formed in one of the third diverging wedge surfaces, the third light source well including a third light source well surface;

a third light source extending into the third light source well, the third light source emitting light into the third diverging wedge; and

a third encapsulant disposed between the third light source and the third light source well surface;

wherein the third wide end surface is optically coupled to the light guide.