Light emitting device

• US 20080315235A1
• Filed: 08/25/2008
• Published: 12/25/2008
• Est. Priority Date: 10/19/2004
• Status: Active Grant

• Current Assignee: Yoshinori Murazaki
• Original Assignee: Yoshinori Murazaki
• Inventors: Murazaki, Yoshinori
• Granted Patent: US 7,733,002 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: C09K 11/0883 Arsenides; Nitrides; Phosphides
• CPC Class Codes: C09K 11/7734 Aluminates
• CPC Class Codes: C09K 11/7739 with halogens
• CPC Class Codes: C09K 11/774 Borates
• CPC Class Codes: C09K 11/7789 Oxysulfides
• CPC Class Codes: H01L 2224/8592 Applying permanent coating, e.g. protective coating
• CPC Class Codes: H01L 33/504 Elements with two or more wavelength conversion materials
• CPC Class Codes: H05B 33/14 characterised by the chemical or physical composition or the arrangement of the electroluminescent material , or by the simultaneous addition of the electroluminescent material in or onto the light source

Abstract

A light emitting device is provided that has a semiconductor light emitting element and a phosphor which converts a part of the luminescence spectrum emitted from the semiconductor light emitting element. The luminescence spectrum of the semiconductor light emitting element is located between a near ultraviolet region and a short-wavelength visible region, and the phosphor is made by adding a red luminescent activator to a base material of a blue luminescent phosphor. Thereby, improving the color shading generated by the dispersion of the spectra of the light emitting elements and obtaining the light emitting device having a high brightness and a good color rendering properties. With the light emitting device, it is possible to provide the light sources for the lighting apparatus of medical treatments, the flash plate of a copying machine, etc., in which a good color rendering property is required.

Claims

1-10. -10. (canceled)

11. A light emitting device comprising a semiconductor light emitting element and a phosphor which converts a part of a luminescence spectrum emitted from the semiconductor light emitting element;

wherein said luminescence spectrum of said semiconductor light emitting element is located between a near ultraviolet region and a short-wavelength visible region,

wherein said phosphor is made by adding a red luminescent activator to a base material of a blue luminescent phosphor.

12. The light emitting device according to claim 11;

wherein the emission wavelength can be adjusted by the added ratio of said red luminescent activator.

13. The light emitting device according to claims 11;

wherein said semiconductor light emitting element has a main peak wavelength more than 360 nm in the ultraviolet region.

14. The light emitting element according to claim 11;

wherein said phosphor is an alkaline earth metal boric halide phosphor activated by at least Mn and Eu.

15. The light emitting element according to claim 11;

wherein said phosphor is represented by a general formula of

(M_1-x-yEu_xM′

_y)₂B₅O₉M″

,

where M is at least one selected from the group consisting of Mg, Ca, Ba, Sr, M′

is at least one selected from the group consisting of Mn, Fe, Cr, Sn, 0.0001≦

x≦

0.5, 0.0001≦

y≦

0.5, and M″

is at least one halogen selected from the group consisting of F, Cl, Br, I.

16. The light emitting device as in one of claim 11;

further comprising a phosphor selected from the group consisting of

an alkaline earth halogen apatite phosphor activated by Eu, or Eu and Mn [(Sr, Ca, Ba, Mg, Zn)₅(PO₄)₃(F, Cl, Br, I);

Eu, Mn],

an alkaline earth metal aluminate phosphor [SrAl₂O₄;

Eu, Sr₄Al₁₄O₂₅;

Eu(Mn), CaAl₂O₄;

Eu(Mn), BaMg₂Al₁₆O₂₇;

Eu, BaMg₂Al₁₆O₁₂;

Eu,Mn, BaMgAl₁₀O₁₇;

Eu(Mn)],

a phosphor of CaO—

Al₂O₃—

SiO₂ including nitride activated by Eu and/or Cr [oxynitride fluoroglass],

a phosphor of M_xSi_yN_z;

Eu (where M is at least one selected from the group consisting of Mg, Ca, Ba, Sr, Zn, z=2/3x+4/3y),

an yttrium aluminate phosphor activated by cerium,

a rare earth acid sulfide phosphor activated by Eu (La₂O₂S;

Eu, Y₂O₂S;

Eu and Gd₂O₂S;

Eu),

an organic complex phosphor activated by Eu [(Sr, Ca, Ba, Mg)₅(PO₄)₃Cl;

Eu, ZnS;

Cu, Zn₂GeO₄;

Mn, (Sr, Ca, Ba, Mg)Ga₂S₄;

Eu and (Sr, Ca, Ba, Mg)₂Si₅N;

Eu].

17. A light emitting device comprising;

a semiconductor light emitting element of which luminescence spectrum is located between a near ultraviolet region and a short-wavelength visible region,

a first phosphor which converts a part of a luminescence spectrum emitted from the semiconductor light emitting element, said first phosphor being made by adding an activator for red light emission to a base material of a blue emitting phosphor,

a second phosphor which can convert a part of the light emitted from the first phosphor to a light having a wavelength in a range from blue region to red region,

wherein a mixed light of the light emitted from the first phosphor and the light emitted from the second phosphor is outputted, said mixed light having a wavelength within a range of white region.

18. The light emitting device according to claim 17;

further comprising a phosphor selected from the group consisting of

an alkaline earth halogen apatite phosphor activated by Eu, or Eu and Mn [(Sr, Ca, Ba, Mg, Zn)₅(PO₄)₃(F, Cl, Br, I);

Eu, Mn],

an alkaline earth metal aluminate phosphor [SrAl₂O₄;

Eu, Sr₄Al₁₄O₂₅;

Eu(Mn), CaAl₂O₄;

Eu(Mn), BaMg₂Al₆O₂₇;

Eu, BaMg₂Al₁₆O₂₇;

Eu,Mn, BaMgAl₁₀O₁₇;

Eu(Mn)],

a phosphor of CaO—

Al₂O₃—

SiO₂ including nitride activated by Eu and/or Cr [oxynitride fluoroglass],

a phosphor of M_xSi_yN_z;

Eu (where M is at least one selected from the group consisting of Mg, Ca, Ba, Sr, Zn, z=2/3x+4/3y),

an yttrium aluminate phosphor activated by cerium,

a rare earth acid sulfide phosphor activated by Eu (La₂O₂S;

Eu, Y₂O₂S;

Eu and Gd₂O₂S Eu),

an organic complex phosphor activated by Eu [(Sr, Ca, Ba, Mg)₅(PO₄)₃Cl;

Eu, ZnS;

Cu, Zn₂GeO₄;

Mn, (Sr, Ca, Ba, Mg)Ga₂S₄;

Eu and (Sr, Ca, Ba, Mg)₂Si₅N₈;

Eu].