White light emitting device

Abstract

A white light emitting device capable of expanding the wavelength range of a blue LED used for realizing white light. The white light emitting device according to the present invention includes a blue LED and a mixture of orange phosphor and green phosphor disposed above the blue LED.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a side sectional view illustrating a white light emitting device according to an embodiment of the present invention;

FIG. 2 is a graph showing the light emission spectrums of ZnSeS:Cu phosphor and β-sialon phosphor;

FIG. 3 is a graph illustrating the light emission spectrum of the white light emitting device according to an embodiment of the present invention;

FIG. 4 is a graph showing the light emission spectrum of a white light emitting device according to another embodiment of the present invention; and

FIG. 5 is a graph showing the light emission spectrum of a white light emitting device according to further another embodiment of the present invention.

Claims

1. A white light emitting device comprising: a blue light emitting diode; anda mixture of orange phosphor and green phosphor disposed above the blue light emitting diode.

2. The white light emitting device according to claim 1, further comprising an encapsulant, for encapsulating the blue light emitting diode, wherein the mixture of the orange phosphor and the green phosphor is dispersed in the encapsulant.

3. The white light emitting device according to claim 1, wherein the orange phosphor has an emission peak of 560 to 590 nm.

4. The white light emitting device according to claim 1, wherein the green phosphor has an emission peak of 510 to 550 nm.

5. The white light emitting device according to claim 1, wherein the orange phosphor comprises a silicate phosphor having a composition expressed by a following formula: (3-x-y)SrO.x(Ba,Ca)O.(1-a-b-c-d)SiO2.aP2O5bAl2O3.cB2O3.dGeO2:yEu2+,where 0≦x<2.4, 0.005<y<0.5 and 0≦a, b, c, d<0.5.

6. The white light emitting device according to claim 1, wherein the orange phosphor comprises a phosphor having a composition expressed by a following formula: Zn1-xSeyS1-y:Cux, where 0<x<0.2 and 0.005<y<1.

7. The white light emitting device according to claim 1, wherein the orange phosphor comprises a Ca-α sialon phosphor having a composition expressed by a following formula: Cax; Si12-(z+w)Alz+wOwN16-w:Euy2+ where 0.5<x<0.9, 0.01<y<0.15, 0<z<4, 0<w<4 and 0<z+w<4.

8. The white light emitting device according to claim 1, wherein the orange phosphor comprises at least two phosphors selected from the group consisting of phosphors having compositions expressed by following formulae: (3-x-y)SrO.x(Ba,Ca)O.(1-a-b-c-d)SiO2.aP2O5bAl2O3.cB2O3.dGeO2:yEu2+, where 0≦x<2.4, 0.005<y<0.5 and 0≦a, b, c, d<0.5;Zn1-xSeyS1-y:Cux, where 0<x<0.2 and 0.005<y<1; andCaxSi12-(z+w)Alz+wOwN16-w:Euy2+, where 0.5<x<0.9, 0.01<y<0.15, 0<z<4, 0<w<4 and 0<z+w<4.

9. The white light emitting device according to claim 1, wherein the green phosphor comprises a phosphor having a composition expressed by a following formula: (Sr1-x-y,Cax)Ga2(Sz,Se1-z)4:Euy2+, where 0≦x<1, 0<y<0.2, 0<x+y≦1 and 0<z<1.

10. The white light emitting device according to claim 1, wherein the green phosphor comprises a phosphor having a composition expressed by a following formula: (Sr1-x-y,Cax,Bay,Mgz)2SiO4:Euw2+ where 0<x<1, 0.5<y<1, 0<z<1, 0.03<w<0.2 and 0<x+y+z+w<1.

11. The white light emitting device according to claim 1, wherein the green phosphor comprises a β-sialon phosphor activated by Eu.

12. The white light emitting device according to claim 1, wherein the green phosphor comprises a phosphor selected from the group consisting of phosphors having compositions expressed ; by following formulae: Y3(Al1-x,Gax)5O12: Ce, where 0<x≦1, SrSi2O2N2: Eu, CaSc2Si3O12:Ce, CaSc2O4:Eu and combinations thereof.

13. The white light emitting device according to claim 1, wherein the green phosphor comprises at least two phosphors selected from the group consisting of phosphors having compositions expressed by following formulae: (Sr1-x-y,Cax)Ga2(Sz,Se1-z)4:Euy2+ where 0≦x<1, 0<y<0.2, 0<x+y≦1 and 0<z≦1;(Sr1-x-y-z,Cax,Bay,Mgz)2SiO4:Euw2+, where 0<x<1, 0.5<y<1, 0<z<1, 0.03<w<0.2 and 0<x+y+z+w<1;Eu-activated β-sialon;Y3(Al1-x,Gax)5O12:Ce, where 0<x≦1; SrSi2O2N2:Eu;CaSc2Si3O12:Ce; andCaSc2O4:Eu.

14. The white light emitting device according to claim 1, wherein the orange phosphor comprises Zn(Se0.1,S0.9) :Cu and the green phosphor comprises Eu-activated β-sialon.

15. The white light emitting device according to claim 1, wherein the orange phosphor comprises Sr3SiO5:Eu and the green phosphor comprises SrGa2S4:Eu.

16. The white light emitting device according to claim 1, wherein the orange phosphor comprises Zn(Se0.1S0.9) :Cu and the green phosphor comprises CaGa2(S,Se)4:Eu.