Light emitting device

• US 8,558,251 B2
• Filed: 08/22/2011
• Issued: 10/15/2013
• Est. Priority Date: 09/06/2010
• Status: Active Grant

• Current Assignee: Alpad Corporation
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Mitsuishi, Iwao, Fukuda, Yumi, Okada, Aoi, Hiramatsu, Ryosuke, Matsuda, Naotoshi, Nunoue, Shinya, Albessard, Keiko, Kato, Masahiro
• Primary Examiner(s): Kuo, W. Wendy
• Assistant Examiner(s): Hossain, Moazzam
• Application Number:
  US13/214,444
• Publication Number:
  US 20120056209A1
• Time in Patent Office: 785 Days
• Field of Search: None
• US Class Current: 257/88
• CPC Class Codes: C09K 11/0883 Arsenides; Nitrides; Phosphides
• CPC Class Codes: C09K 11/77342 Silicates
• CPC Class Codes: F21Y 2105/10 comprising a two-dimensional array of point-like light-generating elements
• CPC Class Codes: F21Y 2105/12 characterised by the geometrical disposition of the light-generating elements, e.g. arranging light-generating elements in differing patterns or densities
• CPC Class Codes: F21Y 2113/10 of different colours
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• 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 33/502 Wavelength conversion materials
• CPC Class Codes: H01L 33/64 Heat extraction or cooling elements

Abstract

A light emitting device according to one embodiment includes a board; plural first light emitting elements mounted on the board to emit light having a wavelength of 250 nm to 500 nm; plural second light emitting elements mounted on the board to emit light having a wavelength of 250 nm to 500 nm; a first fluorescent layer formed on each of the first light emitting elements, the first fluorescent layer including a first phosphor; and a second fluorescent layer formed on each of the second light emitting elements, the second fluorescent layer including a second phosphor. The second phosphor is higher than the first phosphor in luminous efficiency at 50° C., and is lower than the first phosphor in the luminous efficiency at 150° C.

Claims

1. A light emitting device comprising:

a board;

a plurality of first light emitting elements mounted on the board to emit light having a wavelength of 250 nm to 500 nm;

a plurality of second light emitting elements mounted on the board to emit light having a wavelength of 250 nm to 500 nm;

a first fluorescent layer formed on each of the first light emitting elements, the first fluorescent layer including a first phosphor; and

a second fluorescent layer formed on each of the second light emitting elements, the second fluorescent layer including a second phosphor being higher than the first phosphor in luminous efficiency at 50°

C., being lower than the first phosphor in the luminous efficiency at 150°

C.,

wherein the first light emitting elements are mounted on a first region of the board,

the second light emitting elements are mounted on a second region of the board, and

the first region has higher rate of increase in temperature than that of the second region.

5. The device according to claim 1, wherein white-color light is emitted by the first light emitting element and the first fluorescent layer, and white-color light is emitted by the second light emitting element and the second fluorescent layer.

6. The device according to claim 1, wherein the first light emitting element or the second light emitting element is a semiconductor light emitting element that emits ultraviolet light or blue light.

7. The device according to claim 1, wherein the first phosphor has a composition expressed by equation (1) or equation (2), and the second phosphor has a composition expressed by equation (3):

(M<sub>1−

x1</sub>Eu_x1)<sub>3−

y1</sub>Si<sub>13−

z1</sub>O_2+uN<sub>21−

w</sub> 

 

(1)

(In the equation (1), M is an element that is selected from IA group elements, IIA group elements, IIIA group elements, IIIB group elements except Al, rare-earth elements, and IVB group elements, and x1, y1, z1, u, and w satisfy the following relationship;

0<

x1<

1,

−

0.1<

y1<

0.3,

−

3<

z1≦

1,

−

3<

u−

w≦

1.5)

(M′

<sub>1−

x2</sub>Eu_x2)_a1Si_b1AlO_c1N_d1 

 

(2)

(In the equation (2), M′

is an element that is selected from IA group elements, IIA group elements, IIIA group elements, IIIB group elements except Al(Aluminum), rare-earth elements, and IVB group elements, and x2, a1, b1, c1, and d1 satisfy the following relationship;

0<

x2<

1,

0.55<

a1 <

0.95,

2.0<

b1<

3.9,

0<

c1<

0.6,

4<

d1<

5.7)

(Ba<sub>1−

y2−

z2−

x3</sub>Ca_y2Sr_z2Eu_x3)_a2Si_b2O_c2 

 

(3)

(In the equation (3), x3, y2, z2, a2, b2, and c2 satisfy the following relationship;

0<

x3≦

1,

0≦

y2≦

1,

0≦

z2≦

1,

1.5≦

a2<

2.5,

0.5<

b2<

1.5,

3.5<

c2<

4.5).

8. The device according to claim 7, wherein the second fluorescent layer becomes a temperature of 100 °

C. or less in a usage state.

9. The device according to claim 7, wherein white-color light is emitted by the first light emitting element and the first fluorescent layer, and white-color light is emitted by the second light emitting element and the second fluorescent layer.

10. The device according to claim 7, wherein the first light emitting element or the second light emitting element is a semiconductor light emitting element that emits ultraviolet light or blue light.

2. A light emitting device comprising:

a board;

a plurality of first light emitting elements mounted on the board to emit light having a wavelength of 250 nm to 500 nm;

a plurality of second light emitting elements mounted on the board to emit light having a wavelength of 250 nm to 500 nm;

a first fluorescent layer formed on each of the first light emitting elements, the first fluorescent layer including a first phosphor; and

a second fluorescent layer formed on each of the second light emitting elements, the second fluorescent layer including a second phosphor being higher than the first phosphor in luminous efficiency at 50°

C., being lower than the first phosphor in the luminous efficiency at 150°

C.,

wherein packaging density of the first light emitting elements in a first region of the board is higher than that of the second light emitting elements in a second region.

14. The device according to claim 2, wherein the first phosphor has a composition expressed by equation (1) or equation (2), and the second phosphor has a composition expressed by equation (3):

(M<sub>1−

x1</sub>Eu_x1)<sub>3−

y1</sub>Si<sub>13−

z1</sub>Al_3+z1O_2+uN<sub>21−

w</sub> 

 

(1)

(In the equation (1), M is an element that is selected from IA group elements, IIA group elements, IIIA group elements, IIIB group elements except Al, rare-earth elements, and IVB group elements, and x1, y1, z1, u, and w satisfy the following relationship;

0<

x1<

1,

−

0.1<

y1<

0.3,

−

3<

z1≦

1,

−

3<

u−

w≦

1.5)

(M′

<sub>1−

x2</sub>Eu_x2)_a1Si_b1AlO_c1N_d1 

 

(2)

(In the equation (2), M′

is an element that is selected from IA group elements, IIA group elements, IIIA group elements, IIIB group elements except Al(Aluminum), rare-earth elements, and IVB group elements, and x2, a1, b1, c1, and d1 satisfy the following relationship;

0<

x2<

1,

0.55<

a1<

0.95,

2.0<

b1<

3.9,

0<

c1<

0.6,

4<

d1<

5.7)

(Ba<sub>1−

y2−

z2−

x3</sub>Ca_y2Sr_z2Eu_x3)_a2Si_b2O_c2 

 

(3)

(In the equation (3), x3, y2, z2, a2, b2, and c2 satisfy the following relationship;

0<

x3≦

1,

0≦

y2≦

1,

0≦

z2≦

1,

1.5<

a2<

2.5,

0.5<

b2<

1.5,

3.5<

c2<

4.5).

15. The device according to claim 14, wherein the second fluorescent layer becomes a temperature of 100°

C. or less in a usage state.

16. The device according to claim 14, wherein white-color light is emitted by the first light emitting element and the first fluorescent layer, and white-color light is emitted by the second light emitting element and the second fluorescent layer.

3. A light emitting device comprising:

a board;

a plurality of first light emitting elements mounted on the board to emit light having a wavelength of 250 nm to 500 nm;

a plurality of second light emitting elements mounted on the board to emit light having a wavelength of 250 nm to 500 nm;

a first fluorescent layer formed on each of the first light emitting elements, the first fluorescent layer including a first phosphor; and

a second fluorescent layer formed on each of the second light emitting elements, the second fluorescent layer including a second phosphor being higher than the first phosphor in luminous efficiency at 50°

C., being lower than the first phosphor in the luminous efficiency at 150°

C.,

wherein the first light emitting elements are mounted on a first region of the board,

the second light emitting elements are mounted on a second region of the board, and

wherein the first region is surrounded by the second region.

17. The device according to claim 3, wherein the first phosphor has a composition expressed by equation (1) or equation (2), and the second phosphor has a composition expressed by equation (3):

(M<sub>1−

x1</sub>Eu_x1)<sub>3−

y1</sub>Si<sub>13−

z1</sub>Al_3+z1O_2+uN<sub>21−

w</sub> 

 

(1)

In the equation (1), M is an element that is selected from IA group elements, IIA group elements, IIIA group elements, IIIB group elements except Al(Aluminum), rare-earth elements, and IVB group elements, and x1, y1, z1, u, and w satisfy the following relationship;

0<

x1<

1,

−

0.1<

y1<

0.3,

−

3<

z1≦

1,

−

3<

u−

w≦

1.5)

(M′

<sub>1−

x2</sub>Eu_x2)_a1Si_b1AlO_c1N_d1 

 

(2)

(In the equation (2), M′

is an element that is selected from IA group elements, IIA group elements, IIIA group elements, IIIB group elements except Al(Aluminum), rare-earth elements, and IVB group elements, and x2, a1, b1, c1, and d1 satisfy the following relationship;

0<

x2<

1,

0.55<

a1<

0.95,

2.0<

b1<

3.9,

b 0<

c1<

0.6,

4<

d1<

5.7)

(Ba<sub>1−

y2−

z2−

x3</sub>Ca_y2Sr_z2Eu_x3)_a2Si_b2O_c2 

 

(3)

(In the equation (3), x3, y2, z2, a2, b2, and c2 satisfy the following relationship;

0<

x3≦

1,

0≦

y2≦

1,

0≦

z2≦

1,

1.5<

a2<

2.5,

0.5<

b2<

1.5,

3.5<

c2<

4.5).

18. The device according to claim 17, wherein the second fluorescent layer becomes a temperature of 100°

C. or less in a usage state.

19. The device according to claim 17, wherein white-color light is emitted by the first light emitting element and the first fluorescent layer, and white-color light is emitted by the second light emitting element and the second fluorescent layer.

4. A light emitting device comprising:

a board;

a plurality of first light emitting elements mounted on the board to emit light having a wavelength of 250 nm to 500 nm;

a plurality of second light emitting elements mounted on the board to emit light having a wavelength of 250 nm to 500 nm;

a first fluorescent layer formed on each of the first light emitting elements, the first fluorescent layer including a first phosphor; and

a second fluorescent layer formed on each of the second light emitting elements, the second fluorescent layer including a second phosphor being higher than the first phosphor in luminous efficiency at 50°

C., being lower than the first phosphor in the luminous efficiency at 150°

C.,

wherein the first light emitting elements are mounted on a first region of the board,

the second light emitting elements are mounted on a second region of the board, and

wherein a thermal resistance of the board in the first region is larger than that of the board in the second region.

11. The device according to claim 4, wherein the first phosphor has a composition expressed by equation (1) or equation (2), and the second phosphor has a composition expressed by equation (3):

(M<sub>1−

x1</sub>Eu_x1)<sub>3−

y1</sub>Si<sub>13−

z1</sub>Al_3+z1O_2+uN<sub>21−

w</sub> 

 

(1)

(In the equation (1), M is an element that is selected from IA group elements, IIA group elements, IIIA group elements, IIIB group elements except Al(Aluminum), rare-earth elements, and IVB group elements, and x1, y1, z1, u, and w satisfy the following relationship;

0<

x1<

1,

−

0.1<

y1<

0.3,

−

3<

z1≦

1,

−

3<

u−

w≦

1.5)

(M′

<sub>1−

x2</sub>Eu_x2)_a1Si_b1AlO_clN_d1 

 

(2)

(In the equation (2), M′

is an element that is selected from IA group elements, IIA group elements, IIIA group elements, IIIB group elements except Al(Aluminum), rare-earth elements, and IVB group elements, and x2, a1, b1, c1, and d1 satisfy the following relationship;

0<

x2<

1,

−

0.55<

a1<

0.95,

2.0<

b1<

3.9,

0<

c1 <

0.6,

4<

d1<

5.7)

(Ba<sub>1−

y2−

z2−

x3</sub>Ca_y2Sr_z2Eu_x3)_a2Si_b2O_c2 

 

(3)

(In the equation (3), x3, y2, z2, a2, b2, and c2 satisfy the following relationship;

0<

x3≦

1,

0≦

y2≦

1,

0≦

z2≦

1,

1.5<

a2<

2.5,

0.5<

b2<

1.5,

3.5<

c2<

4.5).

12. The device according to claim 11, wherein the second fluorescent layer becomes a temperature of 100°

C. or less in a usage state.

13. The device according to claim 11, wherein white-color light is emitted by the first light emitting element and the first fluorescent layer, and white-color light is emitted by the second light emitting element and the second fluorescent layer.