Phosphor mixture and light emitting device using the same

• US 20060045832A1
• Filed: 11/10/2004
• Published: 03/02/2006
• Est. Priority Date: 08/27/2004
• Status: Active Grant

• Current Assignee: Citizen Electronics Company Limited, Nichia Corporation
• Original Assignee: Dowa Mining Company Limited
• Inventors: Gotoh, Masahiro, Nagatomi, Akira, Sakane, Kenji
• Granted Patent: US 7,345,418 B2
• Time in Patent Office: Days
• US Class Current: 423/325
• CPC Class Codes: C04B 2235/3213 Strontium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3224 Rare earth oxide or oxide forming salts thereof, e.g. scandium oxide
• CPC Class Codes: C04B 2235/3852 Nitrides, e.g. oxynitrides, carbonitrides, oxycarbonitrides, lithium nitride, magnesium nitride
• CPC Class Codes: C04B 2235/3865 Aluminium nitrides
• CPC Class Codes: C04B 2235/3873 Silicon nitrides, e.g. silicon carbonitride, silicon oxynitride
• CPC Class Codes: C04B 35/581 based on aluminium nitride
• CPC Class Codes: C04B 35/584 based on silicon nitride
• CPC Class Codes: C09K 11/642 with zinc or cadmium
• CPC Class Codes: C09K 11/7734 Aluminates
• CPC Class Codes: C09K 11/77348 Silicon Aluminium Nitrides or Silicon Aluminium Oxynitrides
• 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 2924/00014 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 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 33/507 the elements being in intimate contact with parts other than the semiconductor body or integrated with parts other than the semiconductor body
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Abstract

In order to provide a phosphor mixture which contains four or more kinds of phosphors comprising a red phosphor, an orange phosphor, a blue phosphor, and a green phosphor, and produce emission having excellent color rendering not only in the case of white light at a high color temperature, but also in the case of emission in warm white which is low in color temperature, and a light emitting device including the phosphor mixture and a light-emitting section, CaAlSiN₃:Eu and CaAl₂Si₄N₈:Eu are manufactured as a red phosphor and an orange phosphor respectively, and ZnS:Cu, Al, and BAM:Eu are prepared as a green phosphor and a blue phosphor respectively. Then the emission spectrums of these four kinds of phosphors are measured and a relative mixing ratio at which the correlated color temperature of the phosphor mixture becomes a targeted color temperature is determined from the emission spectrum by simulation, and a phosphor mixture is obtained by weighing and mixing the respective phosphors based on the simulation result.

Claims

1. A phosphor mixture, comprising:

a red phosphor expressed by a composition formula of MmAaBbOoNn;

Z (where an element M indicates one or more kinds of elements having a valency of II, an element A indicates one or more kinds of elements having a valency of III, an element B indicates one or more kinds of elements having a valency of IV, O indicates oxygen, N indicates nitrogen, an element Z indicates elements serving as an activator in the phosphors, and m=a=b=1, o<

0.5, n=3−

⅔

o);

an orange phosphor having a maximum peak of an emission spectrum in the wavelength range of 570 to 630 nm;

a green phosphor having a maximum peak of the emission spectrum in the wavelength range of 500 to 570 nm; and

a blue phosphor having a maximum peak of the emission spectrum in the wavelength range of 440 to 500 nm.

2. The phosphor mixture according to claim 1, wherein

said orange phosphor is a phosphor expressed by a composition formula of MmAaBbOoNn:

Z (where an element M indicates one or more kinds of elements having a valency of II, an element A indicates one or more kinds of elements having a valency of III, an element B indicates one or more kinds of elements having a valency of IV, O indicates oxygen, N indicates nitrogen, an element Z indicates elements serving as an activator in the above-described phosphors, and n=⅔

m+a+ 4/3b−

⅔

o (m>

0, a≧

0, b>

0, o≧

0).

3. The phosphor mixture according to claim 1, wherein

said orange phosphor is a phosphor expressed by a composition formula of MmAaBbOoNn:

Z (where an element M indicates elements consisting of one or more kinds of elements having a valency of II, an element A indicates one or more kinds of elements having a valency of III, an element B indicates one or more kinds of elements having a valency of IV, O indicates oxygen, N indicates nitrogen, an element Z indicates elements serving as an activator in the above-described phosphors, and m=1.0, a=2.0, 3.0≦

b≦

6.0, o<

1.0, n= 8/3+ 4/3b−

⅔

o).

4. The phosphor mixture according to claim 1, wherein

said element M comprises one or more kinds of elements selected from Ca, Mg, Sr, Ba, and Zn;

said element A comprises one or more kinds of elements selected from Al and Ga;

said element B comprises one or more kinds of elements selected from Si and Ge; and

said element Z comprises one or more kinds of elements selected from a group consisting of rare earth elements or transition metal elements.

5. The phosphor mixture according to claim 1, wherein said element Z comprises Eu.

6. The phosphor mixture according to claim 1, wherein

each of said respective phosphors has a half band width of 50 nm or more in the emission spectrum.

7. The phosphor mixture according to claim 1, wherein

said phosphor mixture includes a spectrum having a correlated color temperature in the range of 7000 K to 2000 K and being continuous in the wavelength range of 420 nm to 780 nm without breaks in the emission spectrum excited by exciting light in the wavelength range of 300 nm to 420 nm.

8. The phosphor mixture according to claim 1, wherein

said phosphor mixture includes a spectrum having a correlated color temperature in the range of 4500 K to 2000 K, having three or more of emission peak in the wavelength range of 420 nm to 780 nm, and being continuous in the wavelength range of 420 nm to 780 nm without breaks in the emission spectrum excited by exciting light in the wavelength range of 300 nm to 420 nm.

9. The phosphor mixture according to claim 1, wherein

said green phosphor comprises ZnS:

Cu, Al, and/or (Ba, Sr, Ca)₂SiO₄;

Eu.

11. The phosphor mixture according to claim 1, wherein

each of said respective phosphors comprises particles having an average particle size of 0.1 μ

m to 20 μ

m.

12. A light emitting device, comprising:

the phosphor mixture according to claim 1;

and

a light-emitting section producing emission having any wavelength in the wavelength range of 300 nm to 420 nm.

13. The light emitting device according to claim 12, wherein the general color rendering index Ra of said light emitting device is 80 or more.

14. The light emitting device according to claim 12, wherein the special color rendering index R9 of said light emitting device is 60 or more.

15. The light emitting device according to claim 12,

wherein the special color rendering index R15 of said light emitting device is 80 or more.

16. The light emitting device according to claim 12, wherein a correlated color temperature of said light emitting device is in the range of 7000 K to 2500 K.

17. The light emitting device according to claim 12, wherein a correlated color temperature of said light emitting device is in the range of 4500 K to 2500 K.

18. The light emitting device according to claim 12, wherein said light-emitting section comprises a light-emitting diode (LED).

10. The phosphor mixture according to claim, wherein

said blue phosphor comprises BAM:

Eu (BaMgAl₁₀O₁₇;

Eu) and/or (Sr, Ca, Ba, Mg)₁₀(PO₄)₆Cl₂;

Eu.