Light emitting apparatus and light emitting method

• US 20050001225A1
• Filed: 11/28/2003
• Published: 01/06/2005
• Est. Priority Date: 11/29/2002
• Status: Abandoned Application

• Current Assignee: Independent Administrative Institution National Institute For Materials Science, Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Original Assignee: National Institute for Materials Science, Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Inventors: Mitomo, Mamoru, Suehiro, Yoshinobu, Takahashi, Yuji, Ota, Koichi, Endo, Tadashi, Yoshimura, Naoki, Komatsu, Masakazu
• Application Number:
  US10/722,563
• Publication Number:
  US 20050001225A1
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: C04B 2235/3208 Calcium oxide or oxide-forming salts thereof, e.g. lime
• CPC Class Codes: C04B 2235/3217 Aluminum oxide or oxide forming salts thereof, e.g. bauxite, alpha-alumina
• 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 2235/3852 Nitrides, e.g. oxynitrides, carbonitrides, oxycarbonitrides, lithium nitride, magnesium nitride
• CPC Class Codes: C04B 2235/3865 Aluminium nitrides
• CPC Class Codes: C04B 2235/3869 Aluminium oxynitrides, e.g. AlON, sialon
• CPC Class Codes: C04B 2235/3873 Silicon nitrides, e.g. silicon carbonitride, silicon oxynitride
• CPC Class Codes: C04B 2235/766 Trigonal symmetry, e.g. alpha-Si3N4 or alpha-Sialon
• CPC Class Codes: C04B 2235/80 Phases present in the sintered or melt-cast ceramic products other than the main phase
• 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: C04B 35/6455 Hot isostatic pressing
• 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: G02F 1/133614 using photoluminescence, e.g. phosphors illuminated by UV or blue light
• CPC Class Codes: H01L 2224/49107 on the semiconductor or solid-state body
• CPC Class Codes: H01L 2924/01019 Potassium [K]
• CPC Class Codes: H01L 2924/01025 Manganese [Mn]
• CPC Class Codes: H01L 2924/01066 Dysprosium [Dy]
• CPC Class Codes: H01L 2924/01068 : Erbium [Er]
• CPC Class Codes: H01L 2924/01079 : Gold [Au]
• CPC Class Codes: H01L 2924/12041 : LED
• CPC Class Codes: H01L 33/502 : Wavelength conversion materials
• CPC Class Codes: Y02B 20/00 : Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Abstract

A light emitting apparatus has a light emitting element with an emission wavelength in the range of 360 to 550 nm and a rare-earth element doped oxide nitride phosphor or cerium ion doped lanthanum silicon nitride phosphor. Part of light radiated from the light emitting element is wavelength-converted by the phosphor. The light emitting apparatus radiates white light generated by a mixture of the wavelength-converted light and the other part of light radiated from the light emitting element.

Claims

1. A light emitting apparatus, comprising:

a light emitting element with an emission wavelength in the range of 360 to 550 nm; and

a rare-earth element doped oxide nitride phosphor;

wherein part of light radiated from the light emitting element is wavelength-converted by the phosphor.

2. The light emitting apparatus according to claim 1, wherein;

the emission wavelength is in the range of 450 to 550 nm, and the light emitting apparatus radiates white light generated by a mixture of the wavelength-converted light and the other part of light radiated from the light emitting element.

3. The light emitting apparatus according to claim 1, wherein;

the oxide nitride phosphor is of oxide nitride that contains α

-sialon as matrix material.

4. The light emitting apparatus according to claim 1, wherein;

the phosphor is in the form of powder or particles and is contained in a light transmitting material.

5. The light emitting apparatus according to claim 1, wherein;

the light emitting element is III group nitride system compound semiconductor emitting element.

6. The light emitting apparatus according to claim 1, wherein;

the phosphor is represented by a general formula;

Me_xSi<sub>12−

(m+n)</sub>Al_(m+n)O_nN<sub>16−

n</sub>;

Re1_yRe2_z, part or all of metal (Me), where Me is one or more of Li, Ca, mg, Y and lanthanide metals except for La and Ce, to be dissolved into α

-sialon being replaced by lanthanide metal (Re1), where Re1 is one or more of Ce, Pr, Eu, Tb, Yb and Er, as luminescence center, or replaced by lanthanide metal (Re1) and lanthanide metal (Re2), where Re2 is Dy, co-activator.

7. The light emitting apparatus according to claim 6, wherein;

the phosphor satisfies, when the metal (Me) is bivalent, 0.6<

m<

3.0 and 0≦

n<

1.5 in the general formula.

8. The light emitting apparatus according to claim 6, wherein;

the phosphor satisfies, when the metal (Me) is trivalent, 0.9<

m<

4.5 and 0≦

n<

1.5 in the general formula.

9. The light emitting apparatus according to claim 6, wherein;

the phosphor is Me_xSi_9.75Al_2.25O_0.75N_15.25;

Re1_yRe2_z to satisfy m=1.5 and n=0.75 in the general formula, where 0.3<

x+y<

0.75 and 0.01<

y+z<

0.7, where y>

0.01, 0.0≦

z<

0.1, are satisfied.

10. The light emitting apparatus according to claim 6, wherein;

the phosphor is Me_xSi_9.75Al_2.25O_0.75N_15.25;

Re1_yRe2_z to satisfy m=1.5 and n=0.75 in the general formula, where 0.3<

x+z+y+z<

1.5, 0.01<

y<

0.7 and 0.0≦

z<

0.1 are satisfied.

11. The light emitting apparatus according to claim 6, wherein;

the metal (Me) is calcium (Ca).

12. The light emitting apparatus according to claim 1, wherein;

the phosphor is sialon system phosphor powder that is composed of;

α

-sialon of 40 weight % or more and 90 weight % or less, the α

-sialon being structured such that Ca site of Ca-α

-sialon represented by;

(Ca_x, M_y) (Si, Al)₁₂(O, N)₁₆ is partially replaced by metal (M);

β

-sialon of 5 weight % or more and 40 weight % or less; and

unreacted silicon nitride of 5 weight % or more and 30 weight % or less, where M is metal that is one or more selected from Ce, Pr, Eu, Tb, Yb and Er and 0.05<

(x+y)<

0.3, 0.02<

x<

0.27 and 0.03<

y<

0.3.

13. The light emitting apparatus according to claim 12, wherein;

the entire phosphor powder has a chemical composition that is in the range of three composition lines of Si₃N₄-a (M₂O₃. 9AlN), Si₃N₄-b(CaO.3AlN) and Si₃N₄-c(AlN.Al₂O₃), where 4×

10<sup>−

3</sup><

a<

4×

10<sup>−

2</sup>, 8×

10<sup>−

3</sup><

b<

8×

10<sup>−

2</sup> and 10<sup>−

2</sup><

c<

8×

10<sup>−

1</sup> are satisfied.

14. A light emitting apparatus, comprising:

a light emitting element with an emission wavelength in the range of 360 to 550 nm; and

a cerium ion doped lanthanum silicon nitride phosphor;

wherein part of light radiated from the light emitting element is wavelength-converted by the phosphor.

15. The light emitting apparatus according to claim 14, wherein:

the phosphor is represented by;

La_2-xSi₃N₅;

xCe, where doping amount x is 0<

x<

1 and cerium ion is doped to lanthanum site in solid dissolution replacement.

16. The light emitting apparatus according to claim 14, wherein:

the doping amount x is 0.1<

x<

0.5 and the phosphor is ultraviolet ray excitation phosphor.

17. The light emitting apparatus according to claim 14, wherein:

the doping amount x is 0.0<

x<

0.2, and the phosphor is electron beam excitation phosphor.

18. The light emitting apparatus according to claim 14, wherein:

the phosphor radiates blue light.

19. A light emitting method for a light emitting apparatus that comprises a light emitting element with an emission wavelength in the range of 360 to 550 nm and a rare-earth element doped oxide nitride phosphor, wherein part of light radiated from the light emitting element is wavelength-converted by the phosphor, and the light emitting apparatus radiates light generated by a mixture of wavelength-converted light and the other part of light radiated from the light emitting element, comprising the step of:

turning on intermittently the light emitting element.

21. The light emitting method according to claim 19, wherein:

the color of the light radiated from the light emitting apparatus is adjusted by controlling the turn-on time of the light emitting element.

23. The light emitting method according to claim 19, wherein:

the emission wavelength is in the range of 450 to 550 nm, and the light emitting apparatus radiates white light.

25. The light emitting apparatus according to claim 19, wherein;

the light emitting element is III group nitride system compound semiconductor emitting element.

20. A light emitting method for a light emitting apparatus that comprises a light emitting element with an emission wavelength in the range of 360 to 550 nm and a cerium ion doped lanthanum silicon nitride phosphor, wherein part of light radiated from the light emitting element is wavelength-converted by the phosphor, and the light emitting apparatus radiates light generated by a mixture of wavelength-converted light and the other part of light radiated from the light emitting element, comprising the step of:

turning on intermittently the light emitting element.

22. The light emitting method according to claim 20, wherein:

the color of the light radiated from the light emitting apparatus is adjusted by controlling the turn-on time of the light emitting element.

24. The light emitting method according to claim 20, wherein:

the emission wavelength is in the range of 450 to 550 nm, and the light emitting apparatus radiates white light.

26. The light emitting apparatus according to claim 20, wherein;

the light emitting element is III group nitride system compound semiconductor emitting element.