LIGHT EMITTING DIODE ILLUMINATION SYSTEM

• US 20120106192A1
• Filed: 01/06/2012
• Published: 05/03/2012
• Est. Priority Date: 08/06/2007
• Status: Active Grant

• Current Assignee: Lumencor, Inc.
• Original Assignee: Lumencor, Inc.
• Inventors: BRUKILACCHIO, Thomas J.
• Granted Patent: US 8,525,999 B2
• Time in Patent Office: Days
• US Class Current: 362/555
• CPC Class Codes: A61B 1/00163 Optical arrangements A61B1/002, A61B1/06 take precedence
• CPC Class Codes: A61B 1/0653 with wavelength conversion
• CPC Class Codes: A61B 1/0669 at proximal end of an endoscope
• CPC Class Codes: A61B 1/0684 using light emitting diodes [LED]
• CPC Class Codes: A61N 2005/005 for cooling the radiator
• CPC Class Codes: A61N 2005/0652 Arrays of diodes
• CPC Class Codes: A61N 5/062 Photodynamic therapy, i.e. excitation of an agent
• CPC Class Codes: F21K 9/60 Optical arrangements integrated in the light source, e.g. for improving the colour rendering index or the light extraction
• CPC Class Codes: F21K 9/61 using light guides
• CPC Class Codes: F21K 9/64 using wavelength conversion means distinct or spaced from the light-generating element, e.g. a remote phosphor layer
• CPC Class Codes: F21V 13/04 the elements being reflectors and refractors for vehicle rear lights F21S43/40
• CPC Class Codes: F21V 13/08 the elements being filters or photoluminescent elements and reflectors
• CPC Class Codes: F21V 13/14 the elements being filters or photoluminescent elements, reflectors and refractors
• CPC Class Codes: F21V 29/60 characterised by the use of a forced flow of gas, e.g. air
• CPC Class Codes: F21V 29/70 characterised by passive heat-dissipating elements, e.g. heat-sinks
• CPC Class Codes: F21V 5/008 Combination of two or more successive refractors along an optical axis
• CPC Class Codes: F21V 7/0066 specially adapted to cooperate with point like light sources; specially adapted to cooperate with light sources the shape of which is unspecified F21V7/16 - F21V7/30 take precedence
• CPC Class Codes: F21V 9/30 Elements containing photoluminescent material distinct from or spaced from the light source shades F21V1/17; globes, bowls or cover glasses F21V3/08, F21V3/12; refractors F21V5/10; reflectors F21V7/26, F21V7/30; elements with provision for controlling the spectral properties or intensity F21V9/40
• CPC Class Codes: F21W 2131/205 for operating theatres
• CPC Class Codes: F21W 2131/40 Lighting for industrial, commercial, recreational or military use
• CPC Class Codes: F21Y 2105/00 : Planar light sources
• CPC Class Codes: F21Y 2113/00 : Combination of light sources
• CPC Class Codes: F21Y 2113/13 : comprising an assembly of point-like light sources
• CPC Class Codes: F21Y 2115/10 : Light-emitting diodes [LED]
• CPC Class Codes: F21Y 2115/30 : Semiconductor lasers
• CPC Class Codes: G01N 2021/6419 : Excitation at two or more wavelengths
• CPC Class Codes: G01N 2021/6482 : Sample cells, cuvettes
• CPC Class Codes: G01N 21/64 : Fluorescence; Phosphorescence
• CPC Class Codes: G01N 2201/0627 : Use of several LED's for spectral resolution
• CPC Class Codes: G02B 23/2469 : using optical fibres
• CPC Class Codes: G02B 27/0994 : Fibers, light pipes optical fibers per se G02B6/02
• CPC Class Codes: G02B 27/1006 : for splitting or combining different wavelengths G02B27/1086, G02B27/141 take precedence
• CPC Class Codes: G02B 27/143 : using macroscopically faceted or segmented reflective surfaces
• CPC Class Codes: G02B 27/145 : having sequential partially reflecting surfaces
• CPC Class Codes: G02B 6/0006 : Coupling light into the fibre in general G02B6/4298

Abstract

In various embodiments of the invention, a unique construction for Light Emitting Diodes (LEDs) with at least one luminescent rod and extracting optical elements used to generate a variety of high brightness light sources with different emission spectra. In an embodiment of the invention, forced air cooling is used to cool the luminescent rod. In an embodiment of the invention, totally internal reflected light can be redirected outward and refocused. In another embodiment of the invention, light emitted by the luminescent rod is out-coupled for use in a variety of applications.

Claims

1. An illumination system, comprising:

a straight rod having a first end, a second end, and peripheral surface extending longitudinally between the first end and the second end;

a linear array of LEDs which emit light of a first wavelength;

the linear array of LEDs positioned along the peripheral surface of the straight rod such that light of the first wavelength passes into the luminescent rod through the peripheral surface;

the straight rod comprising a luminescent material which absorbs the light of the first wavelength and emits light of a second wavelength;

a reflective element coupled to the first end of the straight rod to reflect light towards the second end of the straight rod; and

the second end of the straight rod forming an outlet aperture for emitting light from the straight rod;

whereby the straight rod generates light of the second wavelength in response to excitation by light of the first wavelength and emits light of the second wavelength through the outlet aperture.

2. The illumination system of claim 1, further comprising a concentrator coupled to the outlet aperture of the straight rod wherein the concentrator receives, concentrates, and transmits light of the second wavelength emitted from the outlet aperture.

3. The illumination system of claim 1, wherein:

the straight rod has a first index of refraction; and

the illumination system includes a concentrator coupled to the outlet aperture of the straight rod wherein the concentrator receives light of the second wavelength emitted from the outlet aperture; and

wherein the concentrator has a second index of refraction approximately identical to the first index of refraction.

4. The illumination system of claim 1, wherein the illumination system is cooled with forced air.

5. The illumination system of claim 1, further comprising a second linear array of LEDs positioned along the peripheral surface of the straight rod.

6. The illumination system of claim 1, wherein the straight rod comprises one of a single crystal Ce:

YAG and a sintered ceramic Ce;

YAG.

7. The illumination system of claim 1, wherein the straight rod comprises a luminescent material selected from:

Lu₃Al₅O₁₂;

Ce³⁺;

Y₃Al₅O₁₂;

Ce³⁺;

Y₃Al_4.8Si_0.2O_11.8N_0.2;

Ce³⁺;

Sr₂Si₅N₈;

Eu³⁺;

SrSi₂N₂O₂;

Eu²⁺;

SrGa₂S₄;

Eu²⁺;

SrBaSiO₄;

Eu²⁺;

CaS;

Eu²⁺;

SrS;

Eu²⁺;

CaAlSiN₃;

Eu²⁺;

CaAl_1.04Si_0.96N₃;

Ce³⁺; and

Ca_0.75Si_8.625Al_3.375N_0.625;

Eu_0.25.

8. The illumination system of claim 1, wherein the straight rod comprises a luminescent material selected from:

(Lu<sub>1−

x−

y−

a−

b</sub>Y_xGd_y)₃(Al<sub>1−

z−

c</sub>Ga_zSi_c)₅O<sub>12−

c</sub>N;

Cea_aPr_b with 0<

x<

1, 0<

y<

1, 0<

z<

/=0.1, 0<

a<

=0.2, 0<

b<

=0.1, and 0<

c<

1; and

(Sr<sub>1−

x−

y</sub>Ba_xCa_y)<sub>2−

z</sub>Si<sub>5−

a</sub>Al_aN<sub>8−

a</sub>O_a;

Eu_z²⁺ where 0<

=a<

5, 0<

x<

=1, 0<

=y<

=1, and 0<

z<

=1;

(Sr<sub>1−

a−

b</sub>Ca_bBa_c)Si_xN_yO_z;

Eu_a²⁺ where a=0.002 to 0.20, b=0.0 to 0.25, c=0.0 to 0.25, x=1.5 to 2.5, y=1.5 to 2.5, and z=1.5 to 2.5;

(Sr<sub>1−

u−

v−

x</sub>Mg_uCa_vBa_x)(Ga<sub>2−

y−

z</sub>Al_zIn_zS₄);

Eu²⁺;

(Sr<sub>1−

x−

y</sub>Ba_xCa_y)₂SiO₄;

Eu²⁺;

(Ca<sub>1−

x</sub>Sr_x)S;

Eu²⁺ where 0<

x<

=1 for example CaS;

Eu²⁺ and SrS;

Eu²⁺;

(Ca<sub>1−

x−

y−

z</sub>Sr_xBa_yMg_z)<sub>1−

x</sub>(Al_1a+bB)Si<sub>1−

b</sub>N<sub>3−

b</sub>O_b;

Eu²⁺ where 0<

=x<

=1, 0<

=y<

=1, 0<

=z<

=1, 0<

=a<

=1, 0<

=b<

=1 and 0.002<

=n<

=0.2; and

(Ca<sub>1−

x−

y−

z</sub>Sr_xBa_yMg_z)<sub>1−

x</sub>(Al_1a+bB)Si<sub>1−

b</sub>N<sub>3−

b</sub>O_b;

Ce³⁺_n where 0<

=x<

=1, 0<

=y<

=1, 0<

=z<

=1, 0<

=a<

=1, 0<

=b<

=1 and 0.002<

=n<

=0.2.

9. The illumination system of claim 1, wherein the luminescent material is M_xv+Si₁₂₋

(m+n)Al_m+nO_nN<sub>16−

n</sub> with x=m/v; and

where M is a metal selected from the group consisting of Li, M, Ca, Y, Sc, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.

10. The illumination system of claim 1, further comprising:

an LED emitting blue light;

an LED emitting red light;

and combiner optics to combine the blue light and the red light with the light of the second wavelength emitted from the outlet aperture.

11. The illumination system of claim 1, further comprising:

an LED emitting blue light;

an LED emitting red light;

and combiner optics to combine the blue light and the red light with the light of the second wavelength emitted from the outlet aperture to create white light having a color rendering index (CRI) no lower than about 85.

12. An illumination system, comprising:

a straight rod having a first end, a second end, and peripheral surface extending longitudinally between the first end and the second end;

a linear array of LEDs which emit blue light;

the linear array of LEDs positioned along the peripheral surface of the straight rod such that the blue light passes into the luminescent rod through the peripheral surface;

the straight rod comprising a luminescent material which absorbs the blue light and emits green light;

a reflective element coupled to the first end of the straight rod to reflect light towards the second end of the straight rod; and

the second end of the straight rod forming an outlet aperture for emitting light from the straight rod;

whereby the straight rod, in response to excitation by blue light, generates green light and emits green light through the outlet aperture.

13. The illumination system of claim 12, further comprising a concentrator coupled to the outlet aperture of the straight rod wherein the concentrator receives, concentrates, and transmits light emitted from the outlet aperture.

14. The illumination system of claim 12, wherein:

the straight rod has a first index of refraction; and

the illumination system includes a concentrator coupled to the outlet aperture of the straight rod wherein the concentrator receives light emitted from the outlet aperture, wherein the concentrator has a second index of refraction approximately identical to the first index of refraction.

15. The illumination system of claim 12, wherein the illumination system is cooled with forced air.

16. The illumination system of claim 12, further comprising a second linear array of LEDs positioned along the peripheral surface of the straight rod.

17. The illumination system of claim 12, wherein the straight rod comprises one of a single crystal Ce:

YAG and a sintered ceramic Ce;

YAG.

18. The illumination system of claim 12, further comprising:

an additional LED emitting blue light;

an LED emitting red light;

and combiner optics to combine the blue light and the red light with the green light emitted from the outlet aperture of the straight rod.

19. The illumination system of claim 12, further comprising:

an additional LED emitting blue light;

an LED emitting red light;

and combiner optics to combine the blue light and the red light with the green light emitted from the outlet aperture to create white light having a color rendering index (CRI) no lower than about 85.

20. An illumination system, comprising:

a straight rod having a first end, a second end, and peripheral surface extending longitudinally between the first end and the second end;

a linear array of LEDs which emit blue light;

the linear array of LEDs positioned along the peripheral surface of the straight rod such that the blue light passes into the luminescent rod through the peripheral surface;

the straight rod comprising a luminescent material which absorbs the blue light and emits green light;

a reflective element coupled to the first end of the straight rod to reflect light towards the second end of the straight rod; and

the second end of the straight rod forming an outlet aperture for emitting light from the straight rod;

a concentrator connected to the outlet aperture of the straight rod wherein the concentrator receives, concentrates, and transmits light emitted from the outlet aperture.

whereby the straight rod, in response to excitation by blue light, generates green light and emits green light through the outlet aperture and the concentrator.

21. The illumination system of claim 20, wherein the straight rod and the concentrator have substantially identical indices of refraction.

22. The illumination system of claim 20, wherein the illumination system is cooled with forced air.

23. The illumination system of claim 20, wherein the straight rod comprises one of a single crystal Ce:

YAG and a sintered ceramic Ce;

YAG.

24. The illumination system of claim 20, further comprising:

an additional LED emitting blue light;

an LED emitting red light;

and combiner optics which combine the blue light and the red light with the green light emitted from the outlet aperture to create white light having a color rendering index (CRI) no lower than about 85.