Group of phosphor particles for light-emitting device, light-emitting device and backlight for liquid crystal display

• US 7,808,012 B2
• Filed: 07/11/2008
• Issued: 10/05/2010
• Est. Priority Date: 07/13/2007
• Status: Active Grant

• Current Assignee: Denka Company Limited, GE Phosphors Technology, LLC
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Terashima, Kenji, Masuda, Masatsugu
• Primary Examiner(s): LE, DUNG ANH
• Application Number:
  US12/171,946
• Publication Number:
  US 20090014741A1
• Time in Patent Office: 816 Days
• Field of Search: 257 80-100, 313486-503, 438/22, 438/48, 438/52
• US Class Current: 257/98
• CPC Class Codes: C04B 2235/3203 Lithium oxide or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3206 Magnesium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3208 Calcium oxide or oxide-forming salts thereof, e.g. lime
• CPC Class Codes: C04B 2235/3224 Rare earth oxide or oxide forming salts thereof, e.g. scandium oxide
• CPC Class Codes: C04B 2235/3225 Yttrium oxide or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3229 Cerium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3852 Nitrides, e.g. oxynitrides, carbonitrides, oxycarbonitrides, lithium nitride, magnesium nitride
• CPC Class Codes: C04B 2235/5436 micrometer sized, i.e. from 1 to 100 micron
• CPC Class Codes: C04B 2235/767 Hexagonal symmetry, e.g. beta-Si3N4, beta-Sialon, alpha-SiC or hexa-ferrites
• CPC Class Codes: C04B 35/22 rich in calcium oxide , e.g. wollastonite C04B35/195 takes precedence
• CPC Class Codes: C04B 35/581 based on aluminium nitride
• CPC Class Codes: C04B 35/584 based on silicon nitride
• CPC Class Codes: C04B 35/597 based on silicon oxynitride, e.g. SIALONS
• CPC Class Codes: C09K 11/0883 Arsenides; Nitrides; Phosphides
• CPC Class Codes: C09K 11/77348 Silicon Aluminium Nitrides or Silicon Aluminium Oxynitrides
• CPC Class Codes: C09K 11/77742 Silicates
• 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 2224/48257 connecting the wire to a die pad of the item
• 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: 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
• 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 group of phosphor particles for a light-emitting device contains a plurality of types of phosphor particles having different emission peak wavelengths, while phosphor particles of a type having a relatively longer emission peak wavelength have a relatively larger median diameter as compared with phosphor particles of a type having a relatively shorter emission peak wavelength.

Claims

1. A group of phosphor particles for a light-emitting device containing, in addition to divalent-europium-activated nitride red phosphor particles expressed in (MI_1-aEu_a)MIISiN₃ with a median diameter R1, at least one type of:

divalent-europium-activated oxynitride green phosphor particles of beta sialon expressed in Eu_bSi_cAl_dO_eN_f with a median diameter G1;

divalent-europium-activated oxynitride yellow phosphor particles of alpha sialon expressed in MII_gEu_hSi_iAl_jO_kN_l with a median diameter Y1; and

trivalent-cerium-activated silicate green phosphor particles expressed in MIV₃(MV_1-mCe_m)₂(SiO₄)₃ with a median diameter G2, wherein

MI represents at least one element selected from Mg, Ca, Sr and Ba, MII represents at least one element selected from Al, Ga, In, Sc, Y, La, Gd and Lu, MIII represents at least one element selected from Li, Na, K, Rb, Cs, Mg, Ca, Sr and Ba, MIV represents at least one element selected from Mg, Ca, Sr and Ba, and MV represents at least one element selected from Al, Ga, In, Sc, Y, La, Gd and Lu,

conditions of 0.001≦

a≦

0.10;

0.005≦

b≦

0.4;

c+d=12;

e+f=16;

0<

g≦

3.0;

0.005≦

h≦

0.4;

i+j=12;

k+l=16; and

0.005≦

m≦

0.5 are satisfied, and

conditions of 1.3≦

R1/G1≦

4.0;

1.3≦

R1/Y1≦

4.0; and

1.3R1/G2≦

4.0 are satisfied.

2. The group of phosphor particles for a light-emitting device according to claim 1, wherein

MII represents at least one element selected from Al, Ga and In.

3. The group of phosphor particles for a light-emitting device according to claim 1, wherein

MV represents at least one element selected from Ga, In, Sc and Y.

4. The group of phosphor particles for a light-emitting device according to claim 1, wherein

said median diameter R1 is in a range of 7 μ

m≦

R1≦

19 μ

m.

5. A light-emitting device including:

a gallium nitride semiconductor light-emitting element capable of emitting primary light having a peak wavelength in a range of 430 nm to 480 nm and a luminescence converter for absorbing said primary light and emitting secondary light having a longer peak wavelength as compared with said primary light, wherein

said luminescence converter is formed with a single resin layer containing the group of phosphor particles of claim 1 and covers said semiconductor light-emitting element.

6. The light-emitting device according to claim 5, wherein

the distribution density of said phosphor particles of a type having a relatively longer fluorescent peak wavelength and a relatively larger median diameter is increased at a position closer to said semiconductor light-emitting element as compared with a position farther from said semiconductor light-emitting element in said resin layer.

7. A backlight for a liquid crystal display, including the light-emitting device of claim 5.