White lamps with enhanced color contrast

• US 7,453,195 B2
• Filed: 11/22/2005
• Issued: 11/18/2008
• Est. Priority Date: 08/02/2004
• Status: Active Grant

• Current Assignee: General Electric Company, Consumer Lighting, LLC (d/b/a GE Lighting) (Savant Systems, LLC)
• Original Assignee: Lumination LLC
• Inventors: Radkov, Emil Vergilov
• Primary Examiner(s): Ton; Toan
• Assistant Examiner(s): Won; Bumsuk
• Application Number:
  US11/285,122
• Publication Number:
  US 20060071589A1
• Time in Patent Office: 1,092 Days
• Field of Search: 313483-487, 428403-406, 2521811-194
• US Class Current: 313/487
• CPC Class Codes: C09K 11/0883 Arsenides; Nitrides; Phosphides
• CPC Class Codes: C09K 11/665 with alkali or alkaline earth metals
• CPC Class Codes: C09K 11/7731 with 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: C09K 11/774 Borates
• CPC Class Codes: C09K 11/7768 with alkaline earth metals
• CPC Class Codes: C09K 11/778 Borates
• CPC Class Codes: C09K 11/7789 Oxysulfides
• CPC Class Codes: C09K 11/7794 Vanadates; Chromates; Molybdates; Tungstates
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/48257 connecting the wire to a die pad of the item
• CPC Class Codes: H01L 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/181 Encapsulation
• 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 lighting apparatus for emitting white light including a semiconductor light source emitting radiation with a peak at from about 250 nm to about 500 nm; a first phosphor having a peak emission between about 450 and 550 nm; and a second phosphor having a peak emission between about 615 and 670 nm; wherein the overall emission spectrum of the lighting apparatus has a depression between about 550 and 615 nm, said depression extending to between about 5% and 25% of the highest intensity of the emission spectrum of the lighting apparatus in the region from 400 to 700 nm. In this apparatus, the red-green color contrast is increased versus the referent illuminant.

Claims

1. A lighting apparatus for emitting white light having enhanced red-green color contrast and comprising:

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

a phosphor blend radiationally coupled to said light source comprising;

a first phosphor material having a peak emission between about 450 and 550 nm and a second phosphor material having a peak emission between about 615 and 670 nm;

wherein an overall emission spectrum of the lighting apparatus has a depression between about 550 and 615 nm, said depression extending to between about 5% and 25% of the highest intensity of the emission spectrum of the lighting apparatus in the region from 400 to 700 nm; and

said second phosphor is free of (Mg,Ca,Sr,Ba,Zn)₄Si₂O₈;

Eu²⁺,Mn²⁺.

2. The lighting apparatus of claim 1, wherein the depression is extending to between about 10% and 20% of the highest intensity of the emission spectrum of the lighting apparatus in the region from 400 to 700 nm.

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

4. The lighting apparatus of claim 1, wherein said first phosphor material comprises at least one of (Ca,Sr,Ba)Al₂O₄:

Eu²⁺;

(Mg,Ca,Sr,Ba)₅(PO₄)₃(F,Cl,Br,OH);

Eu²⁺;

(Ca,Sr,Ba)MgAl₁₀O₁₇;

Eu²⁺,Mn²⁺ and Sr₄Al₁₄O₂₅;

Eu²⁺.

5. The lighting apparatus of claim 1, wherein said second phosphor material comprises at least one of 3.5MgO*0.5MgF₂*GeO₂:

Mn⁴⁺;

CaAlSiN₃;

Eu²⁺ and A₂[MF₆];

Mn⁴⁺ where A=Li, Na, K, Rb or Cs and M=Ge, Si, Sn, Ti or Zr.

6. The lighting apparatus of claim 1, wherein said lighting apparatus has an increased red-green color contrast versus the reference illuminant of the same CCT for all 14 test color samples specified by the CIE.

7. The lighting apparatus of claim 1, wherein said lighting apparatus has a general (R_a) CRI of at least 80.

8. The lighting apparatus of claim 1, wherein said phosphor blend further comprises one or more additional phosphors.

9. The lighting apparatus of claim 8, wherein said one or more additional phosphors are selected from the group including (Ca,Sr,Ba)₂Si_1-cO_4-2c:

Eu²⁺ where 0≦

c<

0.25;

(Ba,Sr,Ca)₅(PO₄)₃(Cl,F,Br,OH);

Sb³⁺, Mn²⁺;

(Mg,Ca, Sr,Ba,Zn)₅(PO₄)₃(F,Cl,Br,OH);

Eu²⁺,Mn²⁺;

(Ba,Sr,Ca)BPO₅;

Eu²⁺,Mn²⁺;

(Sr,Ca)₁₀(PO₄)₆*nB₂O₃;

Eu²⁺;

Sr₂Si₃O₈*2SrCl₂;

Eu²⁺;

BaAl₈O₁₃;

Eu²⁺;

2SrO*0.84P₂O_5*0.16B₂O₃;

Eu²⁺;

(Ba,Sr,Ca)Al₂O₄;

Eu²⁺;

(Y,Gd,Lu,Sc,La)BO₃;

Ce³⁺,Tb³⁺;

Ca₈Mg(SiO₄)₄Cl₂;

Eu²⁺, Mn²⁺;

(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⁺;

(Sr,Ca,Ba,Mg,Zn)₂P₂O₇;

Eu²⁺, Mn²⁺;

(Ca,Sr,Ba,Mg, Zn)₁₀(PO₄)₆(F,Cl,Br,OH)₂;

Eu²⁺,Mn²⁺;

(Gd,Y,Lu,La)₂O₃;

Eu³⁺,Bi³⁺;

(Gd,Y,Lu,La)₂O₂S;

Eu³⁺,Bi³⁺;

(Gd,Y,Lu,La)VO₄;

Eu³⁺,Bi³⁺;

SrY₂S₄;

Eu²⁺;

CaLa₂S₄;

Ce³⁺;

(Ca,Sr)S;

Eu²⁺(Ba,Sr,Ca)MgP₂O₇;

Eu²⁺, Mn²⁺;

(Y,Lu)₂WO₆;

Eu³⁺,Mo⁶⁺;

(Ba,Sr,Ca)_uSi_v(N,O)_w;

Eu²⁺ and (Lu,Ca,Li,Mg,Y)alpha-SiAlON doped with Eu²⁺ and/or Ce³⁺.

10. The lighting apparatus of claim 1, wherein said light source comprises a nitride compound semiconductor represented by the formula In_iGa_jAl_kN, where 0≦

i;

0≦

j, 0≦

k, and i+j+k=1.

11. The lighting apparatus of claim 1, further comprising a filter for preventing radiation from said light source from being emitted from said apparatus or reducing said radiation.

12. The lighting apparatus of claim 1, wherein the phosphor blend is coated on the surface of the light source.

13. The lighting apparatus of claim 1, further comprising an encapsulant surrounding the light source and the phosphor blend.

14. The lighting apparatus of claim 13, wherein the phosphor blend is dispersed in the encapsulant.

15. The lighting apparatus of claim 1, further comprising a reflector.

16. The lighting apparatus of claim 1, wherein a color point of said apparatus lies substantially on the black body locus within 0.020 units in the vertical direction on the 1931 CIE Diagram.

17. The lighting apparatus of claim 1, wherein a CCT of said apparatus is higher than 3000K.

18. The lighting apparatus of claim 1, wherein said first phosphor material comprises at least one of (Ca,Sr,Ba)Al₂O_4:

Eu^2+;

(Mg,Ca,Sr,Ba)₅(PO₄)₃(F,Cl,Br,OH);

Eu²⁺;

(Ca,Sr,Ba)MgAl₁₀O₁₇;

Eu^2+,Mn²⁺ and Sr₄Al₁₄O_25;

Eu^2+;

and said second phosphor material comprises at least one of 3.5MgO*0.5MgF_2*GeO_2;

Mn⁴⁺;

CaAlSiN_3;

Eu²⁺ and A₂[MF₆];

Mn⁴⁺ where A=Li, Na, K, Rb or Cs and M=Ge, Si, Sn, Ti or Zr.

19. A method for making a lighting apparatus for emitting white light having enhanced red-green color contrast, the method including the steps of:

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

providing a phosphor blend comprising;

a first phosphor material having a peak emission between about 450 and 550 nm and a second phosphor material having a peak emission between about 615 and 670 nm; and

radiationally coupling said phosphor blend to said light source, wherein an overall emission spectrum of the lighting apparatus has a depression between about 550 and 615 nm, said depression extending to between about 5% and 25% of the highest intensity of the emission spectrum of the lighting apparatus in the region from 400 to 700 nm; and

said second phosphor is free of (Mg,Ca,Sr,Ba,Zn)₄Si₂O₈;

Eu²⁺,Mn²⁺.

20. The method of claim 19, wherein said first phosphor material comprises at least one of (Ca,Sr,Ba)Al₂O₄:

Eu²⁺;

(Mg,Ca,Sr,Ba)₅(PO₄)₃(F,Cl,Br,OH);

Eu²⁺;

(Ca,Sr,Ba)MgAl₁₀O₁₇;

Eu²⁺, Mn²⁺ and Sr₄Al₁₄O₂₅;

Eu²⁺.

21. The method of claim 19, wherein said second phosphor material comprises at least one of 3.5MgO*0.5MgF₂*GeO₂:

Mn⁴⁺;

CaAlSiN₃;

Eu²⁺ and A₂[MF₆];

Mn⁴⁺ where A=Li, Na, K,Rb or Cs and M=Ge, Si, Sn, Ti or Zr.

22. The method of claim 19, wherein said first phosphor material comprises at least one of (Ca,Sr,Ba)Al₂O_4:

Eu^2+;

(Mg,Ca,Sr,Ba)₅(PO₄)₃(F,Cl,Br,OH);

Eu^2+;

(Ca,Sr,Ba)MgAI₁₀O_17;

Eu^2+, Mn²⁺ and Sr₄AI₁₄O_25;

Eu^2+;

and said second phosphor material comprises at least one of 3.5MgO*0.5MgF_2*GeO_2;

Mn^4+;

CaAlSiN_3;

Eu²⁺ and A₂[MF₆];

Mn⁴⁺ where A=Li, Na, K, Rb or Cs and M=Ge, Si, Sn, Ti or Zr.