Light-emitting device, white light-emitting device, illuminator, and image display

• US 8,269,410 B2
• Filed: 03/17/2006
• Issued: 09/18/2012
• Est. Priority Date: 03/18/2005
• Status: Active Grant

• Current Assignee: Mitsubishi Chemical Corporation (Mitsubishi Chemical Group Corp.)
• Original Assignee: Mitsubishi Chemical Corporation (Mitsubishi Chemical Group Corp.)
• Inventors: Kijima, Naoto, Shimomura, Yasuo, Kaneda, Hideaki, Takeshita, Kimiya
• Primary Examiner(s): Santiago, Mariceli
• Application Number:
  US11/909,009
• Publication Number:
  US 20090140630A1
• Time in Patent Office: 2,377 Days
• Field of Search: 313498-500, 313483-487, 257 98-100
• US Class Current: 313/501
• CPC Class Codes: C09K 11/661 Chalcogenides
• CPC Class Codes: C09K 11/77348 Silicon Aluminium Nitrides or Silicon Aluminium Oxynitrides
• CPC Class Codes: C09K 11/7739 with halogens
• CPC Class Codes: C09K 11/77742 Silicates
• CPC Class Codes: C09K 11/778 Borates
• CPC Class Codes: C09K 11/7784 Chalcogenides
• CPC Class Codes: C09K 11/7788 Oxyhalogenides
• CPC Class Codes: C09K 11/7794 Vanadates; Chromates; Molybdates; Tungstates
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 2224/45015 being circular
• CPC Class Codes: H01L 2224/45124 Aluminium (Al) as principal constituent
• 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 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 24/45 of an individual wire connector
• 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 2924/12036 : PN diode
• CPC Class Codes: H01L 2924/12041 : LED
• CPC Class Codes: H01L 2924/12042 : LASER
• CPC Class Codes: H01L 2924/181 : Encapsulation
• CPC Class Codes: H01L 2924/20752 : larger or equal to 20 microns less than 30 microns
• CPC Class Codes: H01L 2924/20753 : larger or equal to 30 microns less than 40 microns
• 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

To achieve a light-emitting device emitting light with high brightness, closer to natural light, and less color shift due to a small change in intensity of emitted light, in a light-emitting device including a light source emitting light by driving current and at least one wavelength-converting material absorbing at least part of the light from the light source and emitting light having a different wavelength, the color coordinate x₁(17.5) and the color coordinate y₁(17.5) of the light emitted at a driving current density of 17.5 A/cm² and the color coordinate x₁(70) and the color coordinate y₁(70) of the light emitted at a driving current density of 70 A/cm² satisfy the following Expressions (D) and (E):
−0.006≦x₁(17.5)−x₁(70)≦0.006  (D),
−0.006≦y₁(17.5)−y₁(70)≦0.006  (E).

Claims

1. A light-emitting device comprising:

a light source configured to emit light by a driving current; and

at least one wavelength-converting material which absorbs at least a part of the light from the light source and emits light having a different wavelength,

wherein the light-emitting device has an emission efficiency of 32 lm/W or more and a general color rendering index Ra of 80 or more; and

a color coordinate x₁(17.5) and a color coordinate y₁(17.5) of light emitted at a driving current density of 17.5 A/cm², a color coordinate x₁(70) and a color coordinate y₁(70) of light emitted at a driving current density of 70 A/cm², and shift amounts [x₁(17.5)−

x₁(70)] and [y₁(17.5)−

y₁(70)] in the color coordinates x and y satisfy Expressions (F) and (G);

−

0.01≦

x₁(17.5)−

x₁(70)≦

0.01 

 

(F), and

−

0.01≦

y₁(17.5)−

y₁(70)≦

0.01 

 

(G).

2. The light-emitting device according to claim 1, wherein a special color rendering index R₉ is 64 or more.

3. The light-emitting device according to claim 1, wherein

the at least one wavelength-converting material is a phosphor mixture of two or more phosphors;

and

a brightness BR(25), a color coordinate x₂(25), and a color coordinate y₂(25) of fluorescence obtained by exciting the phosphor mixture with blue light having a peak wavelength of 455 nm at 25°

C., and a brightness BR(125), a color coordinate x₂(125), and a color coordinate y₂(125) of fluorescence obtained by exciting the phosphor mixture with the blue light at 125°

C. satisfy Expressions (A), (B), and (C);

0.85≦

BR(125)/BR(25)≦

1.15 

 

(A),

−

0.03≦

x₂(25)−

x₂(125)≦

0.03 

 

(B), and

−

0.03≦

y₂(25)−

y₂(125)≦

0.03 

 

(C).

4. The light-emitting device according to claim 1, wherein the at least one wavelength-converting material comprises at least one green phosphor having a fluorescence intensity peak value in the wavelength range of 500 nm to 550 nm.

5. The light-emitting device according to claim 1, wherein the at least one wavelength-converting material comprises at least one red phosphor having a fluorescence intensity peak value in the wavelength range of 610 nm to 680 nm.

6. A lighting system comprising the light-emitting device according to claim 1.

7. A display comprising the light-emitting device according to claim 1.

8. The light emitting device according to claim 1, wherein a special color rendering index R15 of the light emitting device is 84.

9. The light emitting device according to claim 1, wherein a special color rendering index R15 of the light emitting device is 90.

10. The light emitting device according to claim 1, wherein a correlated color temperature of the light emitting device is in a range of from 5000K to 6500K.

11. The light emitting device according to claim 1, wherein light emitted from the light emitting device includes white light emitted from the at least one wavelength-converting material;

the at least one wavelength-converting material comprises at least one of a green phosphor and a red phosphor;

the green phosphor is selected from the group consisting of MSi₂N₂O₂;

Eu, M-Si—

Al—

O—

N;

Ce, and M-Si—

Al—

O—

N;

Eu, where M denotes one or more alkaline-earth metals, and phosphors comprising at least Ce in a form of luminescent center ions in a host crystal and represented by Formula (1) or (2);

the red phosphor is selected from the group consisting of MSi₇N₁₀;

Eu, M₂Si₅N₈;

Eu, and phosphors represented by Formula (3); and

a maximum intensity of an emission spectrum of the white light in a wavelength range of 500 nm to 650 nm is not higher than 150% of a minimum intensity of the emission spectrum in the wavelength range,

M¹_aM²_bM³_cO_d 

 

(1)

where M¹ denotes a bivalent metal element, M² denotes a trivalent metal element, and M³ denotes a tetravalent metal element, and a, b, c, and d are numbers satisfying;

2.7≦

a≦

3.3,

1.8≦

b≦

2.2,

2.7≦

c≦

3.3, and

11.0≦

d≦

13.0;

M⁴_eM⁵_fO_g 

 

(2)

where M⁴ denotes a bivalent metal element and M⁵ denotes a trivalent metal element, and e, f, and g are numbers satisfying;

0.9≦

e≦

1.1,

1.8≦

f≦

2.2, and

3.6≦

g≦

4.4;

M_aA_bD_cE_dX_e 

 

(3)

where M denotes one or more elements selected from the group consisting of Mn, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, and Yb;

A denotes one or more elements selected from the group consisting of bivalent metal elements other than the elements represented by M;

D denotes one or more elements selected from the group consisting of tetravalent metal elements;

E denotes one or more elements selected from the group consisting of trivalent metal elements;

X denotes one or more elements selected from the group consisting of O, N, and F; and

a, b, c, d, and e are numbers satisfying;

0.00001≦

a≦

0.1,

a+b=1,

0.5≦

c≦

4,

0.5≦

d≦

8,

0.8×

(2/3+4/3×

c+d)≦

e, and

e≦

1.2×

(2/3+4/3×

c+d).

12. The light emitting device according to claim 11, wherein the at least one wavelength-converting material comprises a green phosphor represented by the Formula (2).

13. The light emitting device according to claim 11, wherein the at least one wavelength-converting material comprises a red phosphor represented by the Formula (3) where A denotes Ca and Sr.

14. The light-emitting device according to claim 11, wherein the red phosphor comprises CaAlSiN₃:

Eu.

15. The light-emitting device according to claim 11, wherein the green phosphor comprises an Si garnet phosphor comprising Sc.

16. The light-emitting device according to claim 11, wherein at least one of the red phosphor and the green phosphor has an average particle size of 30 μ

m or less.

17. The light-emitting device according to claim 11, wherein the at least one wavelength-converting material has a brightness at 100°

C. not less than 80% of a brightness at 25°

C.

18. The light-emitting device according to claim 11, wherein the at least one wavelength-converting material has an absorption efficiency for a light with a peak wavelength emitted by the light source of 50% or more, and has an internal quantum efficiency of 40% or more.

19. The light-emitting device according to claim 1, wherein the light source has an emission peak wavelength in a range of 370 nm or more and 500 nm or less.

20. The light-emitting device according to claim 11, wherein:

the at least one wavelength-converting material comprises the green phosphor and the red phosphor; and

a percentage by weight of the green phosphor to a total weight of the green phosphor and the red phosphor is 65% or more and 99% or less.

21. The light-emitting device according to claim 1, further comprising:

an ultraviolet light emitting diode device configured to emit light having a wavelength of 330 nm to 420 nm;

a blue phosphor which is excited by light having a wavelength of 330 nm to 420 nm and has an emission peak length of 420 to 480 nm;

a green phosphor which is excited by light having a wavelength of 330 nm to 420 nm and has an emission peak wavelength in a range of 500 nm to 550 nm; and

a red phosphor which is excited by light having a wavelength of 330 nm to 420 nm and has an emission peak wavelength in a range of 550 nm to 700 nm.

22. The light-emitting device according to claim 11, wherein:

the at least one wavelength-converting material comprises a first wavelength-converting material and a second wavelength-converting material; and

a volume ratio of the second wavelength-converting material to the first wavelength-converting material is 0.05 or more and 1 or less.