LIGHT EMITTING DEVICE

• US 20100225226A1
• Filed: 08/29/2008
• Published: 09/09/2010
• Est. Priority Date: 08/30/2007
• Status: Active Grant

• Current Assignee: Nichia Corporation
• Original Assignee: Nichia Corporation
• Inventors: Murazaki, Yoshinori, Takashima, Suguru, Harada, Masafumi
• Granted Patent: US 8,648,523 B2
• Time in Patent Office: Days
• US Class Current: 313/503
• CPC Class Codes: C09K 11/0883 Arsenides; Nitrides; Phosphides
• CPC Class Codes: C09K 11/7733 with alkali or alkaline earth metals
• CPC Class Codes: C09K 11/77342 Silicates
• CPC Class Codes: C09K 11/77348 Silicon Aluminium Nitrides or Silicon Aluminium Oxynitrides
• CPC Class Codes: C09K 11/774 Borates
• CPC Class Codes: C09K 11/7774 Aluminates
• CPC Class Codes: H01L 2224/32245 the item being metallic
• 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 2224/48257 connecting the wire to a die pad of the item
• CPC Class Codes: H01L 2224/48465 the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
• CPC Class Codes: H01L 2224/49107 on the semiconductor or solid-state body
• 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 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 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 2924/181 Encapsulation
• 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 that has excellent color rendering performance is provided.

The light emitting device comprises a light emitting element, a red phosphor formed from a nitride phosphor and a green phosphor formed from a halosilicate, wherein the emission spectrum has a first peak at a wavelength between 440 nm and 470 nm, a second peak at a wavelength between 510 nm and 550 nm and a third peak at a wavelength between 630 nm and 670 nm, and the minimum relative light emission intensity between the second peak wavelength and the third peak wavelength is 80% or less of whichever the lower of the relative light emission intensity of the second peak wavelength and the relative light emission intensity of the third peak wavelength.

Claims

1. A light emitting device comprising a light emitting element, a red phosphor formed from a nitride phosphor and a green phosphor formed from a halosilicate,

the emission spectrum having a first peak at a wavelength between 440 nm and 470 nm, a second peak at a wavelength between 510 nm and 550 nm and a third peak at a wavelength between 630 nm and 670 nm,

the minimum relative light emission intensity between the second peak wavelength and the third peak wavelength of the emission spectrum being 80% or less of whichever the lower of the relative light emission intensity of the second peak wavelength and the relative light emission intensity of the third peak wavelength.

2. The light emitting device according to claim 1, wherein the red phosphor is activated with Eu and is represented by the following general formula (I):

M¹_wAl_xSi_yB_zN_{((2/3)w+x+(4/3)y+z)};

Eu²⁺ 

 

(I)

wherein M¹ is at least one kind of element selected from the group consisting of Mg, Ca, Sr and Ba, and relations;

0.056≦

w≦

9, x=1, 0.056≦

y≦

18 and 0≦

z≦

0.5 are satisfied.

3. The light emitting device according to claim 1, wherein the green phosphor is represented by the following general formula (II):

(M²<sub>1−

y</sub>R_y)_aMgM³_bM⁴_cO_{(a+2b+(3/2)c)}X₂ 

 

(II)

wherein M² is at least one kind of element selected from the group consisting of Ca, Sr, Ba, Zn and Mn, M³ is at least one kind of element selected from the group consisting of Si, Ge and Sn, M⁴ is at least one kind of element selected from the group consisting of B, Al, Ga and In, X is at least one kind of element selected from the group consisting of F, Cl, Br and I, R is at least one kind of element selected from among the rare earth elements with Eu contained as an essential element, and relations;

0.0001≦

y≦

0.3, 7.0≦

a<

10.0, 3.0≦

b<

5.0 and 0≦

c<

1.0 are satisfied.

4. The light emitting device according to claim 1, wherein the green phosphor is represented by the following general formula (III):

M⁵_xEu_yMgSi_zAl_wO_aX_bN_x 

 

(III)

wherein M⁵ is at least one kind of element selected from the group consisting of Ca, Sr, Ba, Zn and Mn, X is at least one kind of element selected from the group consisting of F, Cl, Br and I, and relations;

6.5≦

x<

8.0, 0.01≦

y≦

2.0, 3.7≦

z≦

4.3, 0<

w≦

0.5, a=x+y+1+2z+( 3/2)w−

b/2−

( 3/2)c, 1.0≦

b≦

1.9 and 0≦

c≦

3.0 are satisfied.

5. The light emitting device according to claim 1, wherein the difference between the peak wavelength of the red phosphor and the peak wavelength of the green phosphor is 120 nm or more.

6. The light emitting device according to claim 1, further comprising a YAG phosphor emitting light excited by the light from the light emitting element, the difference between the peak wavelength of the green phosphor and the peak wavelength of the YAG phosphor being 30 nm or less, the proportion of the added YAG phosphor is 50% or less of the total phosphor in weight percentage.

7. The light emitting device according to claim 6, wherein the YAG phosphor is represented by the following general formula (IV):

M⁶₃M⁷₅O₁₂;

Ce 

 

(IV)

wherein M⁶ is at least one kind of element selected from the group consisting of the rare earth elements, and M⁷ is at least one kind of element selected from the group consisting of B, Al, Ga and In.