DIRECT-LIT BACKLIGHT HAVING LIGHT RECYCLING CAVITY WITH CONCAVE TRANSFLECTOR

• US 20110025947A1
• Filed: 10/15/2010
• Published: 02/03/2011
• Est. Priority Date: 08/27/2005
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Thompson, David Scott, Kienitz, Scott J., Wheatley, John A., Ostlie, Brian W., Schardt, Craig R.
• Granted Patent: US 9,857,518 B2
• Time in Patent Office: Days
• US Class Current: 349/62
• CPC Class Codes: G02B 6/0028 Light guide, e.g. taper
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: G02F 1/133606 including a specially adapted diffusing, scattering or light controlling members
• CPC Class Codes: G02F 1/133613 characterized by the sequence of light sources

Abstract

Direct-lit backlights and associated methods and components are disclosed in which a transflector that partially transmits and partially reflects incident light is shaped to form at least one concave structure facing a back reflector of the backlight. This provides at least one recycling cavity therebetween, the at least one recycling cavity substantially filling the output area of the backlight. At least one light source is disposed behind the output area to inject light into each cavity, and can be positioned in the recycling cavity or behind an aperture in the back reflector. The cavities are preferably shallow and wide, having a width-to-depth ratio of at least 5 or 10, and can provide uniform brightness and color at the output area with sparsely distributed light sources and in a thin profile backlight.

Claims

1. A direct-lit backlight having an output area, comprising:

a back reflector;

a curved transflector that partially transmits and partially reflects incident light, the curved transflector being shaped to form at least one concave structure facing the back reflector to provide one or more recycling cavities therebetween, the one or more recycling cavities substantially filling the output area of the backlight; and

at least one light source disposed behind the output area to inject light into the one or more recycling cavities.

3. The backlight of claim 1, wherein the at least one light source is disposed in the one or more recycling cavities or disposed behind the back reflector.

4. The backlight of claim 1, wherein each recycling cavity is hollow.

5. The backlight of claim 1, wherein the at least one concave structure consists essentially of a single concave structure, and the one or more recycling cavities consists essentially of a single recycling cavity.

6. The backlight of claim 1, wherein the at least one concave structure includes a plurality of concave structures, and the one or more recycling cavities includes a plurality of recycling cavities.

7. The backlight of claim 6, wherein the concave structures each have a concave cross-sectional profile in a first plane and a substantially flat cross-sectional profile in a second plane perpendicular to the first plane.

8. The backlight of claim 6, wherein each of the recycling cavities extends across a dimension of the output area.

9. The backlight of claim 1, wherein the at least one light source comprises a plurality of LEDs.

10. The backlight of claim 9, wherein the plurality of LEDs comprises LEDs that emit in different colors.

11. The backlight of claim 9, wherein the curved transflector is shaped to form a plurality of concave structures facing the back reflector to provide a plurality of recycling cavities, and wherein for each recycling cavity there is at least one LED disposed behind the output area to inject light into such recycling cavity.

12. The backlight of claim 1, wherein the curved transflector consists essentially of a structure selected from the group of a semi-reflective film and a light deflecting film.

13. The backlight of claim 1, wherein the curved transflector includes two films selected from the group of semi-reflective films, light deflecting films, and combinations thereof.

14. The backlight of claim 1, wherein the curved transflector comprises a scored film.

15. The backlight of claim 1, wherein the curved transflector comprises a film held in compression.

16. A display system comprising a display panel and the backlight of claim 1.

17. The system of claim 16, wherein the display panel comprises a liquid crystal display (LCD).

18. The system of claim 17, wherein the system comprises an LCD television.

2. A direct-lit backlight having an output area, comprising:

a back reflector;

curved transflector means for partially transmitting and partially reflecting incident light, the curved transflector means including at least one concave structure facing the back reflector to provide one or more recycling cavities therebetween, the one or more recycling cavities substantially filling the output area of the backlight; and

light source means disposed behind the output area for injecting light into the one or more recycling cavities.

19. A direct-lit backlight having an output area, comprising:

a back reflector;

a transflector that partially transmits and partially reflects incident light, the transflector being shaped to form a plurality of concave structures facing the back reflector to provide a plurality of recycling cavities therebetween, the plurality of recycling cavities substantially filling the output area of the backlight, wherein the concave structures each have concave cross-sectional profiles in both a first and second mutually perpendicular plane; and

at least one light source disposed behind the output area to inject light into the plurality of recycling cavities.