WHITE LIGHT EMITTING DEVICE

• US 20190319175A1
• Filed: 04/16/2018
• Published: 10/17/2019
• Est. Priority Date: 04/16/2018
• Status: Active Grant

• Current Assignee: Lextar Electronics Corporation (Ennostar, Inc.)
• Original Assignee: Lextar Electronics Corporation (Ennostar, Inc.)
• Inventors: CHANG, Cheng-Ping, YU, Zong-Han, HUNG, Kuo-Chan
• Granted Patent: US 10,991,855 B2
• Time in Patent Office: Days
• CPC Class Codes: C09K 11/617 Silicates
• CPC Class Codes: C09K 11/7731 with alkaline earth metals
• CPC Class Codes: C09K 11/77348 Silicon Aluminium Nitrides or Silicon Aluminium Oxynitrides
• CPC Class Codes: C09K 11/7774 Aluminates
• CPC Class Codes: C09K 11/778 Borates
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/483 Containers
• CPC Class Codes: H01L 33/504 Elements with two or more wavelength conversion materials
• 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: H01L 33/54 having a particular shape
• CPC Class Codes: H01L 33/56 Materials, e.g. epoxy or silicone resin
• CPC Class Codes: H01L 33/60 Reflective elements
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Abstract

A white light emitting device includes a blue LED chip having a dominant emission wavelength of about 440-465 nm, and a phosphor layer configured to be excited by the dominant emission wavelength of the blue LED chip. The phosphor layer includes a first phosphor having a peak emission wavelength of about 480-519 nm, a second phosphor having a peak emission wavelength of about 520-560 nm, and a third phosphor having a peak emission wavelength of about 620-670 nm. The first phosphor and the second phosphor both have a garnet structure as represented by A₃B₅O₁₂:Ce, A is selected from the group consisting of Y, Lu, and a combination of thereof, and B is selected from the group consisting of Al, Ga, and a combination of thereof.

Claims

1. A white light emitting device for emitting a white light close to a natural light, comprising:

a blue LED chip configured to emit a light having a dominant emission wavelength of about 440-465 nm; and

a phosphor layer configured to be excited by the light having the dominant emission wavelength of the blue LED chip, the phosphor layer comprising;

a blue-green phosphor having a peak emission wavelength of about 480-519 nm;

a green phosphor having a peak emission wavelength of about 520-560 nm; and

a red phosphor having a peak emission wavelength of about 620-670 nm,

wherein the blue-green phosphor and the green phosphor both have a garnet structure represented by A₃B₅O₁₂;

Ce, A is selected from the group consisting of Y, Lu, and a combination of thereof, and B is selected from the group consisting of Al, Ga and a combination of thereof.

2. The white light emitting device of claim 1, wherein the blue-green phosphor comprises Lu₃Al₅O₁₂:

Ce, Lu₃(Al,Ga)₅O₁₂;

Ce, Y₃(Al,Ga)₅O₁₂;

Ce, (Lu,Y)₃Al₅O₁₂;

Ce, (Lu,Y)₃(Al,Ga)₅O₁₂;

Ce or a combination thereof.

3. The white light emitting device of claim 1, wherein the green phosphor comprises Lu₃Al₅O₁₂:

Ce, Lu₃(Al,Ga)₅O₁₂;

Ce, Y₃(Al,Ga)₅O₁₂;

Ce, (Lu,Y)₃Al₅O₁₂;

Ce, (Lu,Y)₃(Al,Ga)₅O₁₂;

Ce or a combination thereof.

4. The white light emitting device of claim 1, wherein the green phosphor has a doping concentration of Ce that is greater than a doping concentration of Ce of the blue-green phosphor.

5. The white light emitting device of claim 1, wherein the blue-green phosphor and the green phosphor are represented by A₃(Al,Ga)₅O₁₂:

Ce, and the blue-green phosphor has an amount of Ga that is greater than an amount of Ga of the green phosphor.

6. The white light emitting device of claim 1, wherein the blue-green phosphor and the green phosphor are represented by (Lu,Y)₃B₅O₁₂:

Ce, and the green phosphor has an amount of Y that is greater than an amount of Y of the blue-green phosphor.

7. The white light emitting device of claim 1, wherein the red phosphor comprises CaAlSiN₃:

Eu, Sr₂Si₅N₈;

Eu, K₂SiF₆;

Mn⁴⁺, Sr(LiAl₃N₄);

Eu²⁺, or a combination thereof.

8. The white light emitting device of claim 1, wherein a weight ratio of the blue-green phosphor:

the green phosphor;

the red phosphor=(0.05-1);

1;

(0.05-0.25).

9. The white light emitting device of claim 8, wherein the white light emitting device is configured to emit a light having a correlated color temperature (CCT) from 2700K to 3500K, and the weight of the red phosphor is substantially equal to or greater than the blue-green phosphor.

10. The white light emitting device of claim 8, wherein the white light emitting device is configured to emit a light having a correlated color temperature (CCT) from 3750K to 4250K, and the weight of the green phosphor is greater than the blue-green phosphor, and the weight of the blue-green phosphor is greater than the red phosphor.

11. The white light emitting device of claim 8, wherein the white light emitting device is configured to emit a light having a correlated color temperature (CCT) from 5000K to 6500K, and the weight of the green phosphor is substantially equal to or greater than the blue-green phosphor, and the weight of the blue-green phosphor is greater than the red phosphor.

12. The white light emitting device of claim 1, wherein the white light emitting device has a Color Fidelity Index (Rf) that is greater than 93.

13. The white light emitting device of claim 1, wherein the white light emitting device has a Color Gamut Index (Rg) that ranges from 99 to 130.

14. The white light emitting device of claim 1, wherein the white light emitting device has a color rendering index (CRI) that is greater than 95 at correlated color temperature (CCT) of 2700-6500K.