White light LED device

• US 6,936,857 B2
• Filed: 02/18/2003
• Issued: 08/30/2005
• Est. Priority Date: 02/18/2003
• Status: Expired due to Fees

• Current Assignee: Gelcore (General Electric Company), General Electric Company
• Original Assignee: Gelcore (General Electric Company), General Electric Company
• Inventors: Brown, Zena R., Srivastava, Alok, Comanzo, Holly, Setlur, Anant Achyut, Doxsee, Daniel Darcy
• Primary Examiner(s): Lee, Eddie
• Assistant Examiner(s): Gebremariam, Samuel A.
• Application Number:
  US10/368,115
• Publication Number:
  US 20040159846A1
• Time in Patent Office: 924 Days
• Field of Search: 257/89, 257/98, 257/99, 257/252, 313/502, 313/503, 313/504, 313/512, 349/69, 252/301.4 R
• US Class Current: 257/89
• CPC Class Codes: C09K 11/7734 Aluminates
• CPC Class Codes: C09K 11/7774 Aluminates
• 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 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 33/502 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: H05B 33/14 characterised by the chemical or physical composition or the arrangement of the electroluminescent material , or by the simultaneous addition of the electroluminescent material in or onto the light source
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Abstract

A light source including a specific LED and phosphor combination capable of emitting white light for direct illumination. In one embodiment, the light source includes an LED chip emitting in the 460-470 nm range radiationally coupled to a phosphor comprising Ca₈Mg(SiO₄)₄Cl₂:Eu²⁺,Mn²⁺. In a second embodiment, the light source includes an LED chip emitting at about 430 nm and a phosphor comprising a blend of Sr₄Al1₄O₂₅:Eu²⁺ (SAE) and a second phosphor having the formula(Tb_1-x-yA_xRE_y)₃D_zO₁₂, where A is a member selected from the group consisting of Y, La, Gd, and Sm; RE is a member selected from the group consisting of Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, and Lu; D is a member selected from the group consisting of Al, Ga, and In; x is in the range from 0 to about 0.5, y is in the range from about 0 to about 0.2, and z is in the range from about 4 to about 5. Both embodiments produce light having the coordinates x=0.240-0.260 and y=0.340-0.360 on the CIE chromaticity diagram.

Claims

1. A lighting apparatus comprising:

a semiconductor light source emitting radiation having a wavelength in the range of about 430 nm;

a phosphor blend comprising Sr₄Al₁₄O₂₅;

Eu²⁺ (SAE) and a second phosphor having the formula(Tb_1-x-yA_xRE_y)₃D_zO₁₂, where A is a member selected from the group consisting of Y, La, Gd, and Sm;

RE is a member selected from the group consisting of Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, and Lu;

D is a member selected from the group consisting of Al, Ga, and In;

x is in the range from 0 to about 0.5, y is in the range from about 0 to about 0.2, and z is in the range from about 4 to about 5;

the phosphor blend radiationally coupled to the semiconductor light source;

wherein the phosphor is capable of absorbing the radiation emitted by the semiconductor light source and converting the radiation into white light.

2. The lighting apparatus of claim 1, wherein x is from about 0 to about 0 2.

3. The lighting apparatus of claim 1, wherein z is from about 4.6 to about 5.

4. The lighting apparatus of claim 1, wherein the second phosphor has the formula Tb₃Al_4.9O₁₂:

Ce.

5. The lighting apparatus of claim 1, wherein the white light has coordinates on the CIE chromaticity diagram wherein x is in the range 0.240-0.260 and y is in the range 0.340-0.360.

6. The lighting apparatus of claim 1, the semiconductor light source is a light emitting diode (LED).

7. The lighting apparatus of claim 6, wherein the LED comprises a nitride compound semiconductor represented by the formula In_iGa_jAl_kN, where 0≦

i;

0≦

j, 0≦

K, and i+j+k=1.

8. The lighting apparatus of claim 1, wherein the phosphor is coated on the surface of the semiconductor light source.

9. The lighting apparatus of claim 1, further comprising an encapsulant surrounding the semiconductor light source and the phosphor.

10. The lighting apparatus of claim 1, further comprising a reflector cup.

11. Method for forming a lighting apparatus, the method comprising the steps of:

providing a blue LED capable of emitting radiation having a wavelength of from about 460 to about 470 nm;

radiationally coupling a phosphor blend comprising Sr₄Al1₄O₂₅;

Eu²⁺ (SAE) and a second phosphor having the formula(Tb_1-x-yA_xRE_y)₃D_zO₁₂, where A is a member selected from the group consisting of Y, La, Gd, and Sm;

RE is a member selected from the group consisting of Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, and Lu;

D is a member selected from the group consisting of Al, Ga, and In;

x is in the range from 0 to about 0.5, y is in the range from about 0 to about 0.2, and z is in the range from about 4 to about 5, to the semiconductor light source;

wherein the phosphor is capable of absorbing the radiation emitted by the semiconductor light source and converting the radiation into white light having coordinates on the CIE chromaticity diagram wherein x is in the range 0.240-0.260 and y is in the range 0.340-0.360.