Light emitting device provided with a wavelength conversion unit incorporating plural kinds of phosphors

• US 8,729,788 B2
• Filed: 05/05/2010
• Issued: 05/20/2014
• Est. Priority Date: 05/30/2005
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Inoguchi, Tsukasa, Masuda, Masatsugu, Katoh, Masaaki
• Primary Examiner(s): Santiago, Mariceli
• Application Number:
  US12/774,495
• Publication Number:
  US 20100213821A1
• Time in Patent Office: 1,476 Days
• Field of Search: 313498-512, 313483-487
• US Class Current: 313/501
• CPC Class Codes: C09K 11/0883 Arsenides; Nitrides; Phosphides
• CPC Class Codes: C09K 11/77214 Aluminosilicates
• CPC Class Codes: C09K 11/7728 containing europium
• CPC Class Codes: C09K 11/7734 Aluminates
• CPC Class Codes: C09K 11/77342 Silicates
• CPC Class Codes: C09K 11/77348 Silicon Aluminium Nitrides or Silicon Aluminium Oxynitrides
• CPC Class Codes: C09K 11/7739 with halogens
• CPC Class Codes: H01J 1/63 characterised by the luminescent material
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• 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 2933/0041 relating to wavelength conversion elements
• CPC Class Codes: H01L 33/504 Elements with two or more wavelength conversion materials
• CPC Class Codes: H01L 33/505 characterised by the shape, e.g. plate or foil
• CPC Class Codes: H01L 33/508 having a non-uniform spatial arrangement or non-uniform concentration, e.g. patterned wavelength conversion layer, wavelength conversion layer with a concentration gradient of the wavelength conversion material

Abstract

A light-emitting device includes a light-emitting element for emitting primary light, and a wavelength conversion unit for absorbing part of the primary light and emitting secondary light having a wavelength longer than that of the primary light, wherein the wavelength conversion unit includes plural kinds of phosphors having light absorption characteristics different from each other, and then at least one kind of phosphor among the plural kinds of phosphors has an absorption characteristic that can absorb the secondary light emitted from at least another kind of phosphor among the plural kinds of phosphors.

Claims

1. A light-emitting device, comprising:

a light-emitting element for emitting primary light; and

a wavelength conversion unit for absorbing part of the primary light and emitting secondary lights having wavelengths longer than a wavelength of the primary light,

wherein said wavelength conversion unit includes plural kinds of phosphors having different emission peak wavelengths and different median diameters that are in the order of several microns,

the different median diameters are adjusted so that the plural kinds of phosphors have different settling speeds,

the plural kinds of phosphors include a red phosphor for emitting red light and a green phosphor for emitting green light, and

a concentration of the red phosphor adjacent the light-emitting element is higher than a concentration of the green phosphor adjacent the light-emitting element, and

wherein said red phosphor for emitting red light includes a divalent europium-activated nitride phosphor represented by (MIII_1-j,Eu_j)MIVSiN₃, where MIII represents at least one kind of element selected from Mg, Ca, Sr and Ba, MIV represents at least one kind of element selected from Al, Ga, In, Sc, Y, La, Gd and Lu, and j represents a number satisfying 0.001≦

j≦

0.05; and

said green phosphor for emitting green light includes at least one kind selected from

a divalent europium-manganese co-activated aluminate phosphor represented by a(M2,Eu_e,Mn_f)O.bAl₂O₃,

a divalent europium-activated silicate phosphor represented by 2(M1_1-g,Eu_g)O.SiO₂, and

a trivalent cerium-activated silicate phosphor represented by MI₃(MII_1-h,Ce_h)₂(SiO₄)₃,

where M2 represents at least one kind of element selected from Mg, Ca, Sr, Ba and Zn;

a, b, e, and f represent numbers satisfying a>

0, b>

0, 0.1≦

a/b≦

1.0, and 0.3≦

f/e≦

5.0;

M1 represents at least one kind of element selected from Mg, Ca, Sr and Ba;

g represents a number satisfying 0.005≦

g≦

0.10;

MI represents at least one kind of element selected from Mg, Ca, Sr and Ba;

MII represents at least one kind of element selected from Al, Ga, In, Sc, Y, La, Gd and Lu; and

h represents a number satisfying 0.005≦

h≦

0.5.

2. The light-emitting device according to claim 1, wherein a phosphor having a relatively longer emission peak wavelength has a relatively larger median diameter as compared with a phosphor having a relatively shorter emission peak wavelength.

3. The light-emitting device according to claim 1, wherein the plural kinds of phosphors further include a phosphor for emitting blue light;

and

said phosphor for emitting blue light includes at least one kind selected from

a divalent europium-activated halophosphate phosphor represented by (M1,Eu)₁₀(PO₄)₆.Cl₂,

a divalent europium-activated aluminate phosphor represented by a(M2,Eu)O.bAl₂O₃, and

a divalent europium-manganese co-activated aluminate phosphor represented by a(M2,Eu_c,Mn_d)O.bAl₂O₃,

where M1 represents at least one kind of element selected from Mg, Ca, Sr and Ba;

M2 represents at least one kind of element selected from Mg, Ca, Sr, Ba and Zn; and

a, b, c and d represent numbers satisfying a>

0, b>

0, 0.1≦

a/b≦

1.0, and 0.001≦

d/c≦

0.2.

4. The light-emitting device according to claim 1, wherein a phosphor having a relatively longer emission peak wavelength has a greater particle-concentration near said light-emitting element as compared with a phosphor having a relatively shorter emission peak wavelength.

5. A light-emitting device, comprising:

a light-emitting element for emitting primary light; and

a wavelength conversion unit for absorbing part of the primary light and emitting secondary lights having wavelengths longer than a wavelength of the primary light,

wherein the wavelength conversion unit includes plural kinds of phosphors having different emission peak wavelengths and different median diameters,

the plural kinds of phosphors contain activators, and

the different median diameters are adjusted so that the plural kinds of phosphors have different settling speeds,

the plural kinds of phosphors include a red phosphor for emitting red light and a green phosphor for emitting green light, and

a concentration of the red phosphor adjacent the light-emitting element is higher than a concentration of the green phosphor adjacent the light-emitting element, and

wherein said red phosphor for emitting red light includes a divalent europium-activated nitride phosphor represented by (MIII_1-j,Eu_j)MIVSiN₃, where MIII represents at least one kind of element selected from Mg, Ca, Sr and Ba, MIV represents at least one kind of element selected from Al, Ga, In, Sc, Y, La, Gd and Lu, and j represents a number satisfying 0.001≦

j≦

0.05; and

said green phosphor for emitting green light includes at least one kind selected from

a divalent europium-manganese co-activated aluminate phosphor represented by a(M2,Eu_e,Mn_f)O.bAl₂O₃,

a divalent europium-activated silicate phosphor represented by 2(M1_1-g,Eu_e)O.SiO₂, and

a trivalent cerium-activated silicate phosphor represented by MI₃(MII_1-h,Ce_h)₂(SiO₄)₃,

where M2 represents at least one kind of element selected from Mg, Ca, Sr, Ba and Zn;

a, b, e, and f represent numbers satisfying a>

0, b>

0, 0.1≦

a/b≦

1.0, and 0.3≦

f/e≦

5.0;

M1 represents at least one kind of element selected from Mg, Ca, Sr and Ba;

g represents a number satisfying 0.005≦

g≦

0.10;

MI represents at least one kind of element selected from Mg, Ca, Sr and Ba;

MII represents at least one kind of element selected from Al, Ga, In, Sc, Y, La, Gd and Lu; and

h represents a number satisfying 0.005≦

h≦

0.5.

6. A light-emitting device, comprising:

a light-emitting element for emitting primary light; and

a wavelength conversion unit for absorbing part of the primary light and emitting secondary lights having wavelengths longer than a wavelength of the primary light,

wherein the wavelength conversion unit includes plural kinds of phosphors having different emission peak wavelengths and different median diameters,

the emission peak wavelengths are independent of the median diameters, and

the different median diameters are adjusted so that the plural kinds of phosphors have different settling speeds,

the plural kinds of phosphors include a red phosphor for emitting red light and a green phosphor for emitting green light, and

a concentration of the red phosphor adjacent the light-emitting element is higher than a concentration of the green phosphor adjacent the light-emitting element, and

wherein said red phosphor for emitting red light includes a divalent europium-activated nitride phosphor represented by (MIII_1-j,Eu_j)MIVSiN₃, where MIII represents at least one kind of element selected from Mg, Ca, Sr and Ba, MIV represents at least one kind of element selected from Al, Ga, In, Sc, Y, La, Gd and Lu, and j represents a number satisfying 0.001≦

j≦

0.05; and

said green phosphor for emitting green light includes at least one kind selected from

a divalent europium-manganese co-activated aluminate phosphor represented by a(M2,Eu_e,Mn_f)O.bAl₂O₃,

a divalent europium-activated silicate phosphor represented by 2(M1_1-g,Eu_g)O.SiO₂, and

a trivalent cerium-activated silicate phosphor resented by MI₃(MII_1-h,Ce_h)₂(SiO₄)₃,

where M2 represents at least one kind of element selected from Mg, Ca, Sr, Ba and Zn;

a, b, e, and f represent numbers satisfying a>

0, b>

0, 0.1≦

a/b≦

1.0, and 0.3≦

f/e≦

5.0;

M1 represents at least one kind of element selected from Mg, Ca, Sr and Ba;

g represents a number satisfying 0.005≦

g≦

0.10;

MI represents at least one kind of element selected from Mg, Ca, Sr and Ba;

MII represents at least one kind of element selected from Al, Ga, In, Sc, Y, La, Gd and Lu; and

h represents a number satisfying 0.005≦

h≦

0.5.