Optical Mixing and Shaping System for Display Backlights and Displays Incorporating the Same

• US 20120140446A1
• Filed: 08/23/2010
• Published: 06/07/2012
• Est. Priority Date: 08/27/2009
• Status: Active Grant

• Current Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Original Assignee: Dolby Laboratories Licensing Corporation (Dolby Laboratories Incorporated)
• Inventors: Seetzen, Helge, Whitehead, Lorne A., Ward, Gregory J.
• Granted Patent: US 8,434,887 B2
• Time in Patent Office: Days
• US Class Current: 362/97.1
• CPC Class Codes: G02B 5/32 Holograms used as optical elements
• CPC Class Codes: G02B 6/0005 the light guides being of the fibre type G02B6/0003 takes precedence
• CPC Class Codes: G02F 1/1335 Structural association of cells with optical devices, e.g. polarisers or reflectors
• CPC Class Codes: G02F 1/133601 for spatial active dimming
• CPC Class Codes: G02F 1/133605 including specially adapted reflectors
• CPC Class Codes: G02F 1/133609 including means for improving the color mixing, e.g. white
• CPC Class Codes: G03B 21/2033 LED or laser light sources
• CPC Class Codes: G03B 21/208 Homogenising, shaping of the illumination light
• CPC Class Codes: G09G 2320/0238 Improving the black level
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix
• CPC Class Codes: H04N 9/3138 using arrays of modulated light sources electroluminescent display devices G09G3/30

Abstract

A backlight (42, 62) for a display (40, 60) comprises a plurality of independently controllable light sources (48) and inclined surfaces inclining in a radially outward direction from each light source for shaping the distribution of emitted light. The light sources (48) may each comprise a group of differently-colored light emitters. The backlight 842, 62) may include light integrators (64) configured to mix light of the differently-colored light emitters. Inclined surfaces (44) for shaping the distribution of emitted light may be arranged around exits of the light integrators (64).

Claims

1. A backlight for illuminating a spatial light modulator of a display, the backlight comprising:

a two-dimensional array of independently-controllable light sources;

the light sources located in cavities, the cavities each comprising one or more reflective surfaces inclined in a radially inward direction toward one of the light sources.

2. A backlight according to claim 1 wherein the inclined surfaces of adjacent light sources adjoin along upper edges forming apexes.

3. A backlight according to claim 2 wherein a radial slope of the inclined surfaces is substantially constant.

4. A backlight according to claim 2 wherein a radial slope of the inclined surfaces increases towards the apexes.

5. A backlight according to claim 1 wherein the inclined surfaces are arranged around the light sources in a regular pattern that tiles the backlight.

6. A backlight according to claim 5 wherein each light source is surrounded by six inclined surfaces and the cavities are arranged in a tiled hexagonal pattern.

7. A backlight according to claim 5 wherein each light source is surrounded by four inclined surfaces and the cavities are arranged in a tiled square pattern.

8. A backlight according to claim 1 wherein each light source comprises a group of light emitters having different spectral compositions.

9. A backlight according to claim 1 wherein point spread functions of neighboring light sources overlap at values greater than 40% of their maximum values and point spread functions of non-neighboring light sources overlap at values less than 5% of their maximum values.

10. A backlight according to claim 1 wherein point spread functions of neighboring light sources overlap at values greater than 45% of their maximum value and point spread functions of non-neighboring light sources overlap at values less than 1% of their maximum value.

11. A backlight according to claim 1 comprising a controller that estimates total light intensities at a point on the spatial light modulator based on brightness levels of no more than a nearest light source and its immediate neighbors.

12. A backlight according to claim 1 wherein the light sources are arranged on the backlight in a regular two-dimensional grid and are separated from their nearest neighbors by a length.

13. A backlight according to claim 12 comprising a controller that estimates total light intensities at a point on the spatial light modulator based on brightness levels of no more than the nearest four light sources.

15. A backlight according to claim 9 wherein the light integrators are configured to mix the light received at their entrances and to emit mixed light toward the spatial light modulator.

16. A backlight according to claim 10 wherein the light integrators comprise diffusely reflective interior walls.

17. A backlight according to claim 11 wherein an interior body of the light integrators is hollow.

18. A backlight according to claim 11 wherein an interior body of the light integrators comprises a clear solid material.

19. A backlight according to claim 13 wherein the clear solid material comprises an acrylic-based plastic.

20. A backlight according to claim 13 wherein the light integrators comprise diffusing centers embedded in the clear solid material.

21. A backlight according to claim 11 wherein the light integrators are cylindrical.

22. A backlight according to claim 11 wherein the light integrators comprise transparent glass or plastic rods coated with white paint.

23. A backlight according to claim 11 wherein the exit of the light integrators comprises a transmissive diffuser.

24. A backlight according to claim 18 wherein the transmissive diffuser has a full-width at half-maximum (FWHM) angle in the range of 30°

to 80°

.

25. A backlight according to claim 11 wherein entrances of the light integrators comprise transmissive diffusers.

26. A backlight according to claim 11 wherein the light emitters of each light source comprise red, green and blue light emitters.

27. A backlight according to claim 11 wherein a height of the light integrators is in the range of 4 mm to 16 mm.

28. A backlight according to claim 11 wherein a height of the inclined surfaces is in the range of 4 mm to 16 mm.

29. A backlight according to claim 11 wherein a distance between the light sources and the spatial light modulator is in the range of 25 mm to 50 mm.

30. A display comprising a spatial light modulator and a backlight according to any one of claims 1 to 29.

14. A backlight for illuminating a spatial light modulator of a display, the backlight comprising:

a plurality of independently controllable light sources, each light source comprising a group of two or more light emitters having different spectral compositions;

a light integrator coupled to each light source such that the group of light emitters of the corresponding light source emits light into an entrance of the light integrator; and

one or more inclined reflective surfaces inclining in a radially inward direction toward the spatial light modulator from an exit of each of the light integrators.

31. Apparatus comprising any new and inventive feature, combination of features, or sub-combination of features as described and/or depicted herein.

32. Methods comprising any new and inventive steps, acts, combinations of steps and/or acts, or sub-combinations of steps and/or acts as described and/or depicted herein.