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

• US 9,028,718 B2
• Filed: 06/26/2012
• Issued: 05/12/2015
• 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): Koslow, Carol M
• Application Number:
  US13/533,242
• Publication Number:
  US 20120267997A1
• Time in Patent Office: 1,050 Days
• Field of Search: 313/498, 313/512, 252/301.4 F
• US Class Current: 252/301.4F
• 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 white light emitting device comprising:

a light source configured to emit light; and

at least one wavelength converting-material configured to absorb at least a part of the light emitted from the light source and configured to emit light having different wavelengths,

wherein the white-light emitting device emits white light comprising the light emitted by the wavelength-converting material,

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

said wavelength converting-material comprises at least one green phosphor and comprises at least one red phosphor represented by formula (3);

M_aA_bD_cE_dX_e 

 

(3)

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

A represents one or two elements selected from the group consisting of divalent metallic elements other than the M;

D represents one or more elements selected from the group consisting of quadrivalent metallic elements;

E represents one or more elements selected from the group consisting of trivalent metallic elements;

X represents one or more elements selected from the group consisting of 0, 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×

(⅔

+ 4/3×

c+d)≦

e, and

e≦

1.2×

(⅔

+ 4/3×

c+d).

2. The white light emitting device according to claim 1, wherein c and d in the formula (3) satisfy:

0.5≦

c≦

1.8, and

0.5≦

d≦

1.8.

3. The white light emitting device according to claim 1, wherein a luminance of said green phosphor in 100°

C. is 80% or more of a luminance of said green phosphor in 25°

C.

4. The white light emitting device according to claim 1, wherein said green phosphor is at least one selected from the group consisting of an oxide, a nitride, and an oxynitride.

5. The white light emitting device according to claim 1, wherein said green phosphor is at least one green phosphor selected from the group consisting of MSi₂N₂O₂ 2:

Eu, M-Si—

Al—

O—

N;

Ce, M-Si—

Al—

O—

N;

Eu (where M represents one or more alkaline earth metals), and a phosphor which comprises at least Ce as a luminescence center ion in a host crystal represented by formula (1) or (2),

M¹_aM²_bM³_cO_d 

 

(1)

where M¹ represents a divalent metallic element, M² represents a trivalent metallic element, M³ represents a quadrivalent metallic element, and a, b, c, d, and e 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 represents a divalent metallic element, M⁵ represents a trivalent metallic 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.

6. The white light emitting device according to claim 1, wherein a general color rendering index Ra prescribed in JIS-Z8726 is 90 or greater.

7. The white light emitting device according to claim 1, wherein a brightness of the wavelength-converting material at 100°

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

C.

8. The white light emitting device according to claim 1, wherein an absorption efficiency of the wavelength-converting material for a light with a peak wavelength emitted by the light source is 50% or more, and an internal quantum efficiency of the wavelength-converting material is 40% or more.

9. A lighting system comprising:

the white light emitting device according to claim 1.

10. The white light emitting device according to claim 1, wherein the green phosphor comprises at least one of Ca₃Sc₂Si₃O₁₂:

Ce and Mg-activated Ca₃Sc₂Si₃O₁₂;

Ce.

11. The white light emitting device according to claim 1, wherein the green phosphor is Ca₃Sc₂Si₃O₁₂:

Ce.

12. The white light emitting device according to claim 1, wherein the green phosphor is Mg-activated Ca₃Sc₂Si₃O₁₂:

Ce.

13. The white light emitting device according to claim 1, wherein the green phosphor comprises at least one of Ca_2.97Ce_0.03Se_1.97Mg_0.03Si₃O₁₂, Ca_2.97Ce_0.03Sc_1.94Mg_0.06Si₃O₁₂, Ca_2.94Ce_0.03Sc_1.94Mg_0.06Si₃O₁₂, Ca_2.94Ce_0.06Sc_1.97Mg_0.03Si₃O₁₂, Ca_2.94Ce_0.06Sc_1.94Mg_0.06Si₃O₁₂, Ca_2.94Ce_0.06S_1.9Mg_0.1Si₃O₁₂, Ca_2.9Ce_0.1Sc_1.97Mg_0.03Si₃O₁₂, and Ca_2.9Ce_0.1Sc_1.94Mg_0.06Si₃O₁₂.

14. The white light emitting device according to claim 1, wherein the green phosphor comprises at least one of Ce_0.01Ca_0.99Sc₂O₄, Ce_0.007Ca_0.993Sc₂O₄, and Ce_0.013Ca_0.987Sc₂O₄.

15. The white light emitting device according to claim 1, wherein the green phosphor comprises at least one of Ce_0.01Ca_0.94Sr_0.05Se₂O₄, Ce_0.01Ca_0.89Sr_0.1Sc₂O₄, and Ce_0.01Ca_0.84Sr_0.15Sc₂O₄.

16. The white light emitting device according to claim 1, wherein in the formula (3), X represents N.

17. The white light emitting device according to claim 1, wherein in the formula (3), X represents a mixture of O and N.

18. The white light emitting device according to claim 1, wherein the wavelength converting-material is a mixture of Ca₃Sc₂Si₃O₁₂:

Ce and CaAlSiN₃;

Eu.