Phosphor based illumination system having a plurality of light guides and a display using same

• US 7,407,313 B2
• Filed: 03/27/2007
• Issued: 08/05/2008
• Est. Priority Date: 06/30/2004
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Wheatley, John A., Weber, Michael F., Ouderkirk, Andrew J., Epstein, Kenneth A., Schardt, Craig R., Schultz, John C., Watson, James E.
• Primary Examiner(s): O'Shea; Sandra
• Assistant Examiner(s): CRANSON JR, JAMES W
• Application Number:
  US11/691,782
• Publication Number:
  US 20070195549A1
• Time in Patent Office: 497 Days
• Field of Search: 362/609, 362/560, 362/616
• US Class Current: 362/609
• CPC Class Codes: G02B 6/0008 the light being emitted at the end of the fibre
• CPC Class Codes: G02B 6/0018 Redirecting means on the surface of the light guide
• CPC Class Codes: G02B 6/0021 for housing at least a part of the light source, e.g. by forming holes or recesses
• CPC Class Codes: G02B 6/0026 Wavelength selective element, sheet or layer, e.g. filter or grating
• CPC Class Codes: G02B 6/0028 Light guide, e.g. taper
• CPC Class Codes: G02B 6/0046 Tapered light guide, e.g. wedge-shaped light guide
• CPC Class Codes: G02B 6/005 provided by one optical element, or plurality thereof, placed on the light output side of the light guide
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources

Abstract

An illumination system including a light source, light guides coupled to the light source, each including an input surface and an output surface, emissive material positioned to receive light from at least one light guide, and a first interference reflector positioned between the emissive material and the output surfaces of the light guides is disclosed. The light source emits light having a first optical characteristic. The emissive material emits light having a second optical characteristic when illuminated with light having the first optical characteristic. The first interference reflector substantially transmits light having the first optical characteristic and substantially reflects light having the second optical characteristic.

Claims

1. A display, comprising:

an illumination system, wherein the illumination system comprises;

a light source that emits light comprising a first optical characteristic;

a plurality of light guides optically coupled to the light source, wherein each light guide comprises an input surface and an output surface;

emissive material positioned to receive light from at least one light guide of the plurality of light guides, wherein the emissive material emits light comprising a second optical characteristic when illuminated with light comprising the first optical characteristic; and

a first interference reflector positioned between the emissive material and the output surfaces of the plurality of light guides, wherein the first interference reflector substantially transmits light comprising the first optical characteristic and substantially reflects light comprising the second optical characteristic; and

a spatial light modulator optically coupled to the illumination system, wherein the spatial light modulator comprises a plurality of controllable elements operable to modulate at least a portion of light from the illumination system.

2. The display of claim 1, wherein the illumination system further comprises a second interference reflector positioned such that the emissive material is between the second interference reflector and the first interference reflector, wherein the second interference reflector substantially transmits light comprising the second optical characteristic and substantially reflects light comprising the first optical characteristic.

3. The display of claim 1, wherein the plurality of controllable elements of the spatial light modulator comprises variable-transmissivity display elements.

4. The display of claim 3, wherein the variable-transmissivity display elements comprises liquid crystal display elements.

5. The system of claim 1, wherein the first optical characteristic comprises a first wavelength region and the second optical characteristic comprises a second wavelength region different than the first wavelength region.

6. The system of claim 5, wherein the first wavelength region comprises UV light.

7. The system of claim 5, wherein the first wavelength region comprises blue light.

8. The system of claim 1, wherein the emissive material is discontinuous.

9. The system of claim 8, wherein the discontinuous emissive material comprises a plurality of dots of emissive material.

10. The system of claim 9, wherein each dot of the plurality of dots of emissive material has an area of less than 10000 μ

m².

11. The system of claim 9, wherein at least one dot of the plurality of dots of emissive material comprises a first emissive material and at least one other dot of the plurality of dots of emissive material comprises a second emissive material.

12. The system of claim 9, wherein the first optical characteristic comprises a first wavelength region and the second optical characteristic comprises a second wavelength region different than the first wavelength region, wherein at least a first dot emits light having a first peak wavelength within the second wavelength region and at least a second dot emits light having a second peak wavelength within the second wavelength region different than the first peak wavelength.

13. The system of claim 1, wherein the first optical characteristic comprises a first wavelength region and the second optical characteristic comprises a second wavelength region different than the first wavelength region, wherein the emissive material comprises a first index of refraction at the first wavelength region.

14. The system of claim 13, wherein the system further comprises a TIR promoting layer in contact with the emissive material between the interference reflector and the emissive material, and further wherein the TIR promoting layer comprises a second index of refraction at the first wavelength region that is less than the first index of refraction.

15. The system of claim 1, further comprising at least one optical element positioned such that the interference reflector is between the emissive material and the at least one optical element.

16. The system of claim 15, wherein the at least one optical element comprises a reflective polarizer.

17. A sign comprising an illumination system, wherein the illumination system comprises:

a light source that emits light comprising a first optical characteristic;

a plurality of light guides optically coupled to the light source, wherein each light guide comprises an input surface and an output surface;

emissive material positioned to receive light from at least one light guide of the plurality of light guides, wherein the emissive material emits light comprising a second optical characteristic when illuminated with light comprising the first optical characteristic; and

a first interference reflector positioned between the emissive material and the output surfaces of the plurality of light guides, wherein the first interference reflector substantially transmits light comprising the first optical characteristic and substantially reflects light comprising the second optical characteristic.