FLUORESCENT VOLUME LIGHT SOURCE HAVING MULTIPLE FLUORESCENT SPECIES

• US 20080079910A1
• Filed: 09/27/2007
• Published: 04/03/2008
• Est. Priority Date: 09/29/2006
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: English, Ronald E., Auerbach, Roy A., Lutz, Dale R., Rutherford, Todd S.
• Granted Patent: US 7,857,457 B2
• Time in Patent Office: Days
• US Class Current: 353/84
• CPC Class Codes: G02B 6/0003 the light guides being doped with fluorescent agents
• CPC Class Codes: G03B 21/2013 Plural light sources
• CPC Class Codes: G03B 21/204 using secondary light emission, e.g. luminescence or fluorescence using different colours G03B33/00; if related to video signals H04N9/3197
• CPC Class Codes: G03B 21/208 Homogenising, shaping of the illumination light

Abstract

A projection system contains an illumination system having at least a first source of incoherent light capable of generating light in a first wavelength range. The illumination system also includes a body containing a fluorescent material that emits light in a second wavelength range, different from the first wavelength range, when illuminated by light in the first wavelength range. The system further includes at least a second fluorescent material that absorbs light in at least one of the first and second wavelength ranges, and emits light in a third wavelength range. The body has an extraction area, and at least some of the light in either the second or third wavelength ranges is internally reflected within the body to the extraction area. Light from the extraction area illuminates at least one image-forming device. Image light from the image-forming device is projected by a projection lens unit onto a screen.

Claims

1. A projection system, comprising:

an illumination system;

a projection unit comprising at least one image-forming device;

a projection lens unit; and

a screen,

the illumination system further comprising;

at least a first source of incoherent light capable of generating light in a first wavelength range;

a body containing a first fluorescent material that emits light in a second wavelength range, different from the first wavelength range, when illuminated by light in the first wavelength range; and

at least a second fluorescent material receiving at least some of the light of at least one of the first and the second wavelength ranges, said second fluorescent material generating light of a third wavelength range,

the body having an extraction area, at least some of the light of at least one of the second wavelength and the third wavelength being internally reflected within the body to the extraction area;

wherein light in at least one of the second wavelength range and the third wavelength range illuminates the at least one image-forming device, image light from the at least one image forming device being projected by the projection lens unit to the screen.

2. A system as recited in claim 1, wherein the light in at least one of the second wavelength range and the third wavelength range is incoherent light.

3. A system as recited in claim 2, wherein light passing out of the light extraction area in at least one of the second and third wavelength ranges has a higher brightness than the brightness of the first wavelength range light entering the body from the at least a first source.

4. A system as recited in claim 1, wherein the second fluorescent material is within the body.

5. A system as recited in claim 1, further comprising a second source of incoherent light capable of generating light in a fourth wavelength range.

6. A system as recited in claim 1, wherein the concentration of the first fluorescent material is not uniform throughout the body.

7. A system as recited in claim 1, wherein the second fluorescent material comprises a phosphor layer adjacent at least one surface of the body.

8. A system as recited in claim 7, wherein the at least one surface of the body comprises the extraction area.

9. A system as recited in claim 8, further comprising an output extractor disposed adjacent to the phosphor layer, the output extractor being optically coupled to extract the light in the third wavelength range out of the phosphor layer.

10. A system as recited in claim 1, further comprising a second body adjacent the first body, the second body comprising the second fluorescent material.

11. A system as recited in claim 10 wherein the first body and second body are in physical contact.

12. A system as recited in claim 10, wherein the first body has at least one input surface different from its extraction surface, and the second body comprises an extraction surface adjacent to the at least one input surface of the first body.

13. A system as recited in claim 12, wherein a refractive index of the first body is approximately equal to or greater than a refractive index of the second body.

14. A system as recited in claim 1, wherein the second fluorescent material absorbs at least a portion of the light in the second wavelength range.

15. A system as recited in claim 1, wherein the body comprises a dichroic coating on a portion of its surface.

16. A system as recited in claim 1, wherein the at least a first source of incoherent light comprises a first source and at least a second source, the sources having one of the same or different source spectra, and further wherein the output spectrum of the light emitted through the extraction surface can be adjusted by adjusting the relative intensities of the first and second sources.

17. A system as recited in claim 16, wherein the portion of the output spectrum of the light transmitted through the extraction surface in the third wavelength range can be adjusted by adjusting the relative intensities of the first and second sources.

18. A system as recited in claim 1, wherein at least a portion of the energy absorbed by the first fluorescent material when illuminated by light in the first wavelength range is non-radiatively transferred to the second fluorescent material.

19. A system as recited in claim 1, wherein at least one of the first, second, and third wavelength ranges is at least partially outside the visible spectrum.

20. A system as recited in claim 1, further comprising a controller coupled to control an image formed by the at least one image-forming device.

21. An illumination system capable of producing a beam of illumination light, comprising:

a body containing at least a first fluorescent material, the body having at least one pump area and a light extraction area; and

at least one light emitting diode (LED) capable of generating light at a first wavelength, at least some of the light at the first wavelength passing through the at least one pump area into the body, fluorescent light at a second wavelength being generated in the body following absorption of the light at the first wavelength, a second fluorescent material receiving light of at least one of the first and second wavelengths and generating light of a third wavelength, at least some of the light of at least one of the second and third wavelengths being directed by the body towards the light extraction area, at least some of the light of at least one of the second and third wavelengths passing through the light extraction area as part of the beam of illumination light.

22. A system as recited in claim 21, wherein light passing out of the light extraction area of at least one of the second or third wavelengths has a higher brightness than the brightness of the first wavelength light passing in through the at least one pump area.

23. An illumination system, comprising:

at least a first solid state source of incoherent light capable of generating light in a first wavelength range;

a body containing a first fluorescent material that emits light in a second wavelength range, different from the first wavelength range, when illuminated by light in the first wavelength range; and

at least a second fluorescent material receiving at least some of the light of at least one of the first and the second wavelength ranges, said second fluorescent material generating light of a third wavelength range,

the body having an extraction area, at least some of the light of at least one of the second wavelength and the third wavelength being internally reflected within the body to the extraction area.

24. A method of generating bright light having a desired spectrum, comprising:

providing at least a first source of incoherent light capable of generating light in a first wavelength range;

providing a body containing a first fluorescent material that emits light in a second wavelength range, different from the first wavelength range, when illuminated by light in the first wavelength range; and

providing at least a second fluorescent material that emits light in a third wavelength range when illuminated by light in at least one of the first and second wavelength ranges;

the body having an extraction area, such that at least some of any light of at least one of the second wavelength and the third wavelength emitted within the body would be internally reflected within the body to the extraction area; and

illuminating the body with the incoherent light from the first source.