LIGHT EMITTING DEVICE WITH OPTICAL REDUNDANCY

• US 20130208508A1
• Filed: 07/28/2011
• Published: 08/15/2013
• Est. Priority Date: 07/28/2010
• Status: Active Grant

• Current Assignee: FLEx Lighting II, LLC
• Original Assignee: FLEx Lighting II, LLC
• Inventors: Nichol, Anthony J., Coleman, Zane A.
• Granted Patent: US 9,103,956 B2
• Time in Patent Office: Days
• US Class Current: 362/612
• CPC Class Codes: G02B 6/0013 Means for improving the coupling-in of light from the light source into the light guide coupling light into light guides in general G02B6/42
• CPC Class Codes: G02B 6/0028 Light guide, e.g. taper
• CPC Class Codes: G02B 6/0043 provided on the surface of the light guide
• CPC Class Codes: G02B 6/0058 varying in density, size, shape or depth along the light guide
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources
• CPC Class Codes: G02B 6/0073 Light emitting diode [LED]
• CPC Class Codes: G02B 6/0076 Stacked arrangements of multiple light guides of the same or different cross-sectional area

Abstract

An optically redundant light emitting device includes a light transmitting film comprising an array of coupling light-guides extending from a light emitting area defined within the light transmitting film. Each coupling lightguide is bent to form a stacked array of coupling lightguides. A first group of light sources comprising at least one light source is positioned to emit light into the stacked array of coupling lightguides, and a second group of light sources comprising at least one light source is positioned to emit light into the stacked array of coupling lightguides. A first optical path of the light emitted from the first group of light sources overlaps with a second optical path of the light from the second group of light sources in each coupling lightguide.

Claims

1. An optically redundant light emitting device comprising:

a. a light transmitting film comprising an array of coupling lightguides extending from a light emitting area defined within the light transmitting film wherein each coupling lightguide of the array of coupling lightguides is bent to form a stacked array of coupling lightguides;

b. a first group of light sources comprising at least one light source positioned to emit light into the stacked array of coupling lightguides; and

c. a second group of light sources comprising at least one light source positioned to emit light into the stacked array of coupling lightguides, wherein;

i) when the first group of light sources and the second group of light sources are emitting light, each coupling lightguide in the stacked array of coupling lightguides receives light emitted from the first group of light sources and light emitted from the second group of light sources, the light travels by total internal reflection through the light transmitting film to the light emitting area, the light emitted from the first group of light sources and the light emitted from the second group of light sources exit the light transmitting film in the light emitting area with a VESA 9-spot sampled spatial luminance uniformity greater than 70%; and

ii) when the first group of light sources is emitting light and the second group of light sources is not emitting light, the light emitted from the first group of light sources exits the light transmitting film in the light emitting area with a VESA 9-spot sampled spatial luminance uniformity greater than 70%.

5. The light emitting device of claim [5] wherein the first group of light sources has a first color temperature and the second group of light sources has a second color temperature different than the first color temperature.

2. The light emitting device of claim [5] wherein at least one of the first group of light sources and the second group of light sources comprises at least two light emitting diodes.

3. The light emitting device of claim 2 wherein the first group of light sources and the second group of light sources are positioned to form a linear array of light sources.

4. The light emitting device of claim [5] wherein the first group of light sources and the second group of light sources each comprises at least two light emitting diodes.

6. The light emitting device of claim [5] wherein at least one of the light emitted from the first group of light sources and the light emitted from the second group of light sources has an angular light output profile with an angular full-width at half maximum intensity less than 80 degrees.

7. The light emitting device of claim [5] wherein the first group of light sources and the second group of light sources comprise light emitting diodes from different luminance bins.

8. The light emitting device of claim [5] wherein:

a. when the first group of light sources and the second group of light sources are emitting light, the light emitted from the first group of light sources and the light emitted from the second group of light sources exit the light transmitting film in the light emitting area with a VESA 9-spot sampled spatial color non-uniformity (Δ

u′

v′

₁) less than 0.2; and

b. when the first group of light sources is emitting light and the second group of light sources is not emitting light, the light emitted from the first group of light sources exits the light transmitting film in the light emitting area with a VESA 9-spot sampled spatial color non-uniformity (Δ

u′

v′

₂) less than 0.2.

9. The light emitting device of claim 8 wherein Δ

u′

v′

₁ is less than 0.1 and Δ

u′

v′

₂ is less than 0.1.

10. The light emitting device of claim 8 wherein the first group of light sources has a first color temperature and the second group of light sources has a second color temperature different than the first color temperature.

11. A display comprising the light emitting device of claim [5] and a spatial light modulator operatively coupled to the light emitting device.

13. The light emitting device of claim [5] wherein the light emitting area has a VESA 9-spot sampled spatial luminance uniformity greater than 70% when the first group of light sources and the second group of light sources are emitting light and when only the first group of light sources is emitting light.

14. The light emitting device of claim [5] wherein the first group of light sources and the second group of light sources are positioned to form a linear array of light sources.

15. The light emitting device of claim [5] wherein the first group of light sources and the second group of light sources each comprises at least two light emitting diodes.

16. A display comprising the light emitting device of claim [5] and a spatial light modulator operatively coupled to the light emitting device.

18. The light emitting device of claim [7] wherein the first group of light sources and the second group of light sources each comprises white light emitting diodes.

19. The light emitting device of claim 18 wherein the first group of light sources has a first color temperature and the second group of light sources has a second color temperature different than the first color temperature.

20. The light emitting device of claim 19 wherein the first group of light sources and the second group of light sources comprise light emitting diodes from different color bins.

21. A display comprising the light emitting device of claim [7] and a spatial light modulator operatively coupled to the light emitting device.

12. An optically redundant light emitting device comprising:

a. a light transmitting film comprising an array of coupling lightguides extending from a light emitting area defined within the light transmitting film wherein each coupling lightguide of the array of coupling lightguides is bent to form a stacked array of coupling lightguides;

b. a first group of light sources comprising at least one light source positioned to emit light into the stacked array of coupling lightguides; and

c. a second group of light sources comprising at least one light source positioned to emit light into the stacked array of coupling lightguides,

wherein a first optical path of the light emitted from the first group of light sources overlaps with a second optical path of the light from the second group of light sources in each coupling lightguide.

17. A light emitting device comprising:

a. a light transmitting film comprising an array of coupling lightguides extending from a light emitting area defined within the light transmitting film wherein each coupling lightguide of the array of coupling lightguides is bent to form a stacked array of coupling lightguides;

b. a first group of light sources comprising at least one light source of a first color positioned to emit light into the stacked array of coupling lightguides; and

c. a second group of light sources comprising at least one light source of a second color different from the first color positioned to emit light into the stacked array of coupling lightguides,

wherein each coupling lightguide in the stacked array of coupling lightguides is positioned to receive light emitted from the first group of light sources and light emitted from the second group of light sources, and the light emitting area has a VESA 9-spot sampled spatial color non-uniformity (Δ

u′

v′

) less than 0.2 when the first group of light sources and the second group of light sources are emitting light and when only the first group of light sources is emitting light.