White LEDs with tunable CRI

• US 20060022582A1
• Filed: 08/02/2004
• Published: 02/02/2006
• Est. Priority Date: 08/02/2004
• Status: Active Grant

• Current Assignee: Savant Technologies, LLC (Savant Systems, LLC)
• Original Assignee: Gelcore (General Electric Company)
• Inventors: Radkov, Emil
• Granted Patent: US 7,768,189 B2
• Time in Patent Office: Days
• US Class Current: 313/503
• CPC Class Codes: C09K 11/665 with alkali or alkaline earth metals
• CPC Class Codes: C09K 11/7734 Aluminates
• CPC Class Codes: C09K 11/7738 with alkaline earth metals
• CPC Class Codes: C09K 11/7739 with halogens
• CPC Class Codes: F21K 9/00 Light sources using semiconductor devices as light-generating elements, e.g. using light-emitting diodes [LED] or lasers
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48257 connecting the wire to a die pad of the item
• CPC Class Codes: H01L 2224/8592 Applying permanent coating, e.g. protective coating
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 33/502 Wavelength conversion materials
• CPC Class Codes: H01L 33/504 Elements with two or more wavelength conversion materials
• CPC Class Codes: H10K 50/125 specially adapted for multicolour light emission, e.g. for emitting white light
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Abstract

A method for the manufacturing of white LEDs is proposed, which can achieve a tunable color rendering index (CRI) or luminosity through the use of at least two phosphor composition layers of essentially the same emission color coordinates, each composition including at least one individual phosphor compound. The method allows to optimize the devices for CRI at a given minimal luminosity requirement, or vice versa.

Claims

1. A lighting apparatus for emitting white light comprising:

a semiconductor light source emitting radiation having a peak emission at from about 250 to 500 nm;

a first phosphor composition comprising at least one phosphor compound radiationally coupled to said light source; and

a second phosphor composition comprising at least one phosphor compound radiationally coupled to said light source;

wherein said first and second phosphor compositions have substantially the same emission color coordinates when excited by the same source radiation.

2. The lighting apparatus of claim 1, further including a pigment, filter or other absorber capable of absorbing radiation generated between 250 nm and 450 nm.

3. The lighting apparatus of claim 1, wherein at least one of said first and second phosphor compositions comprises two or more phosphor compounds.

4. The lighting apparatus of claim 1, wherein at least one of said first and second phosphor compositions includes a phosphor compound having an emission band with a maximum between about 615 nm and 680 nm.

5. The lighting apparatus of claim 4, wherein at least one of said first and second phosphor compositions includes a phosphor compound having an emission band with a maximum between about 625 nm and 660 nm.

6. The lighting apparatus of claim 1, wherein at least one of said first and second phosphor compositions includes a phosphor compound having an emission band with a maximum between about 575 to 615 nm.

7. The lighting apparatus of claim 1, wherein at least one of said first and second phosphor compositions includes a phosphor compound having an emission band with a maximum between about 500 to 575 nm.

8. The lighting apparatus of claim 1, wherein at least one of said first and second phosphor compositions includes a phosphor compound having an emission band with a maximum between about 400 to 500 nm.

9. The lighting apparatus of claim 1, wherein said first and second phosphor compositions have color points within 0.020 units of each other in both x and y color coordinates on the CIE chromaticity diagram.

10. The lighting apparatus of claim 1, wherein at least one of the CRI and luminosity of said light apparatus can be changed by modifying the relative amounts of said first and second phosphor compositions present in said apparatus.

11. The lighting apparatus of claim 10, wherein said lighting apparatus has substantially the same color point on the CIE chromaticity diagram regardless of the relative amounts of said first and second phosphor compositions present in said apparatus.

12. The lighting apparatus of claim 1, wherein a color point of said lighting apparatus lies on or substantially on the black body locus of the CIE chromaticity diagram.

13. The lighting apparatus of claim 1, wherein said first and second phosphor compositions are in the form of discrete layers.

14. The lighting apparatus of claim 1, wherein said first and second phosphor compositions comprise one or more phosphor compounds selected from the group consisting of (Mg,Ca,Sr,Ba,Zn)₄Si₂O₈:

Eu²⁺, Mn²⁺;

3.5MgO*0.5MgF₂*GeO₂;

Mn⁴⁺;

(Ca,Sr,Ba)₅(PO₄)₃(F,Cl,Br,OH);

Eu²⁺;

(Ca,Sr,Ba)Mg_xAl_yO_(1+x+1.5y);

Eu²⁺, wherein x is an integer between about 1 and 5 and y is an integer between about 5 and 25;

(Mg,Ca,Sr,Ba,Zn)₂P₂O₇;

Eu²⁺,Mn²⁺;

(Mg,Ca,Sr,Ba,Zn)₅(PO₄)₃(F,Cl,Br,OH);

Eu²⁺,Mn²⁺;

(Ba,Sr,Ca)₅(PO₄)₃(Cl,F,Br,OH);

Eu²⁺, Mn²⁺,Sb³⁺;

(Ba,Sr,Ca)BPO₅;

Eu²⁺, Mn²⁺;

(Sr,Ca)₁₀(PO₄)₆*nB₂O₃;

Eu²⁺;

(Mg,Ca,Sr, Ba,Zn)₃B₂O₆;

Eu²⁺;

2SrO*0.84P₂O₅*0.16B₂O₃;

Eu²⁺;

Sr₂Si₃O₈*2SrCl₂;

Eu²;

Ba₃MgSi₂O₈;

Eu²⁺;

Sr₄Al₁₄O₂₅;

Eu²⁺;

BaAl₈O₁₃;

Eu²⁺;

(Ba,Sr,Ca)MgAl₁₀O₁₇;

Eu²⁺,Mn²⁺;

(Ba,Sr,Ca)Al₂O₄;

Eu²⁺;

(Y,Gd,Lu,Sc,La)BO₃;

Ce³⁺,Tb³⁺;

Ca₈Mg(SiO₄)₄Cl₂;

Eu²⁺,Mn²⁺;

(Ba,Sr,Ca)₂SiO₄;

Eu²⁺;

(Ba,Sr,Ca)₂(Mg,Zn)Si₂O₇;

Eu²⁺;

(Sr,Ca,Ba)(Al,Ga,In)₂S₄;

Eu²⁺;

(Y,Gd,Tb,La,Sm,Pr,Lu)₃(Al,Ga)₅O₁₂;

Ce³⁺;

(Ca,Sr)₈(Mg,Zn)(SiO₄)₄Cl₂;

Eu²⁺, Mn²⁺;

Na₂Gd₂B₂O₇;

Ce³⁺,Tb³⁺;

(Ba,Sr)₂(Ca,Mg,Zn)B₂O₆;

K,Ce,Tb;

(Gd,Y,Lu,La)₂O₃;

Eu³⁺,Bi³⁺;

(Gd,Y,Lu,La)₂O₂S;

Eu³⁺,Bi³⁺;

(Gd,Y,Lu,La)VO₄;

Eu³⁺,Bi³⁺;

(Ca,Sr)S;

Eu²⁺, SrY₂S₄;

Eu²⁺;

CaLa₂S₄;

Ce³⁺;

(Y,Lu)₂WO₆;

Eu³⁺,Mo⁶⁺;

(Mg,Ca,Sr,Ba,Zn)_v(Si,Ge)_yN_(2v/3+4y/3);

Eu²⁺;

(Mg,Ca,Sr,Ba,Zn)v(Si,Ge)_yO_zN_{(2v/3+4y/3+2z/3)};

Eu²⁺; and

A_2-2xNa_1+xE_xD₂V₃O₁₂, wherein A may be Ca, Ba, Sr, or combinations thereof, E may be Eu, Dy, Sm, Tm, or Er, or combinations thereof, D may be Mg or Zn, or combinations thereof and x ranges from 0.01 to 0.3.

15. A method for making a lighting apparatus for emitting white light which can achieve a tunable color rendering index (CRI) and luminosity, the method including the steps of

providing a semiconductor light source emitting radiation having a peak emission at from about 250 to 500 nm;

providing a first phosphor composition comprising at least one phosphor compound radiationally coupled to said light source; and

providing a second phosphor composition comprising at least one phosphor compound radiationally coupled to said light source;

wherein the first and second phosphor compositions have substantially the same emission color coordinates when excited by the same source radiation.

16. The method of claim 15, further comprising providing a pigment, filter or other absorber capable of absorbing radiation generated between 250 nm and 450 nm to absorb radiation emitted from said light source.

17. The method of claim 15, wherein at least one of said first and second phosphor compositions includes a phosphor compound having an emission band with a maximum between about 615 nm and 680 nm.

18. The method of claim 15, wherein at least one of said first and second phosphor compositions includes a phosphor compound having an emission band with a maximum between about 575 to 615 nm.

19. The method of claim 15, wherein at least one of said first and second phosphor compositions includes a phosphor compound having an emission band with a maximum between about 500 to 575 nm.

20. The method of claim 15, wherein at least one of said first and second phosphor compositions includes a phosphor compound having an emission band with a maximum between about 400 to 500 nm.

21. The method of claim 15, wherein said first and second phosphor compositions have color points within 0.020 units of each other in both x and y color coordinates on the CIE chromaticity diagram.

22. The method of claim 15, wherein at least one of the CRI and luminosity of said light apparatus can be changed by modifying the relative amounts of said first and second phosphor compositions present in said apparatus.

23. The method of claim 22, wherein said lighting apparatus has substantially the same color point on the CIE chromaticity diagram regardless of the relative amounts of said first and second phosphor compositions present in said apparatus.

24. The method of claim 15, wherein said first and second phosphor compositions comprise one or more phosphor compounds selected from the group consisting of (Mg,Ca,Sr,Ba,Zn)₄Si₂O₈:

Eu²⁺,Mn²⁺;

3.5MgO*0.5MgF₂*GeO₂;

Mn⁴⁺ (Ca,Sr,Ba)₅(PO₄)₃(F,Cl,Br,OH);

Eu²⁺;

(Ca,Sr,Ba)Mg_xAl_yO_(1+x+1.5y);

Eu²⁺, wherein x is an integer between about 1 and 5 and y is an integer between about 5 and 25;

(Mg,Ca,Sr,Ba,Zn)₂P₂O₇;

Eu²⁺, Mn²⁺;

(Mg,Ca,Sr,Ba,Zn)₅(PO₄)₃(F,Cl,Br,OH);

Eu²⁺,Mn²⁺;

(Ba,Sr,Ca)₅(PO₄)₃(Cl,F,Br,OH);

Eu²⁺,Mn²⁺,Sb³⁺;

(Ba,Sr,Ca)BPO₅;

Eu²⁺, Mn²⁺;

(Sr,Ca)₁₀(PO₄)₆*nB₂O₃;

Eu²⁺;

(Mg,Ca,Sr,Ba,Zn)₃B₂O₆;

Eu²⁺2SrO*0.84P₂O₅*0.16B₂O₃;

Eu²⁺;

Sr₂Si₃O₈*2SrCl₂;

Eu² Ba₃MgSi₂O₈;

E²⁺;

Sr₄Al₁₄O₂₅;

Eu²⁺;

BaAl₈O₁₃;

Eu²⁺;

(Ba,Sr,Ca)MgAl₁₀O₁₇;

Eu²⁺, Mn²⁺;

(Ba,Sr,Ca)Al₂O₄;

Eu²⁺;

(Y,Gd,Lu,Sc,La)BO₃;

Ce³⁺,Tb³⁺;

Ca₈Mg(SiO₄)₄Cl₂;

Eu²⁺, Mn²⁺;

(Ba,Sr,Ca)₂SiO₄;

Eu²⁺;

(Ba,Sr,Ca)₂(Mg,Zn)Si₂O₇;

Eu²⁺;

(Sr,Ca,Ba)(Al,Ga,In)₂S₄;

Eu²⁺;

(Y,Gd,Tb,La,Sm,Pr,Lu)₃(Al,Ga)₅O₁₂;

Ce³⁺;

(Ca,Sr)₈(Mg,Zn)(SiO₄)₄Cl₂;

Eu²⁺, Mn²⁺;

Na₂Gd₂B₂O₇;

Ce³⁺,Tb³⁺;

(Ba,Sr)₂(Ca,Mg,Zn)B₂O₆;

K,Ce,Tb;

(Gd,Y,Lu,La)₂O₃;

Eu³⁺, Bi³⁺;

(Gd,Y,Lu,La)₂O₂S;

Eu³⁺Bi³⁺;

(Gd,Y,Lu,La)VO₄;

Eu³⁺Bi³⁺;

(Ca,Sr)S;

Eu²⁺, SrY₂S₄;

Eu²⁺;

CaLa₂S₄;

Ce³⁺;

(Y,Lu)₂WO₆;

Eu³⁺,Mo⁶⁺;

(Mg,Ca,Sr,Ba,Zn)_v(Si,Ge)_yN_(2v/3+4y/3);

Eu²⁺;

(Mg,Ca,Sr,Ba,Zn)_v(Si,Ge)_yO_zN_{(2v/3+4y/3+2z/3)};

Eu²⁺; and

A_2-2xNa_1+xE_xD₂V₃O₁₂, wherein A may be Ca, Ba, Sr, or combinations thereof, E may be Eu, Dy, Sm, Tm, or Er, or combinations thereof, D may be Mg or Zn, or combinations thereof and x ranges from 0.01 to 0.3.