White light emitting phosphor blend for LED devices

• US 6,501,100 B1
• Filed: 05/15/2000
• Issued: 12/31/2002
• Est. Priority Date: 05/15/2000
• Status: Expired due to Fees

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Srivastava, Alok Mani, Comanzo, Holly Ann
• Primary Examiner(s): Chaudhuri, Olik
• Assistant Examiner(s): LOUIE, WAI SING
• Application Number:
  US09/571,379
• Time in Patent Office: 960 Days
• Field of Search: 257/79, 257/80, 257/81, 257/98, 257/100, 257/103
• US Class Current: 257/79
• CPC Class Codes: C09K 11/7734 Aluminates
• CPC Class Codes: C09K 11/7738 with alkaline earth metals
• 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 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 33/504 Elements with two or more wavelength conversion materials
• 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: H10K 50/125 specially adapted for multicolour light emission, e.g. for emitting white light
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Abstract

There is provided a white light illumination system including a radiation source, a first luminescent material having a peak emission wavelength of about 570 to about 620 nm, and a second luminescent material having a peak emission wavelength of about 480 to about 500 nm, which is different from the first luminescent material. The LED may be a UV LED and the luminescent materials may be a blend of two phosphors. The first phosphor may be an orange emitting Eu²⁺, Mn²⁺ doped strontium pyrophosphate, (Sr_0.8Eu_0.1Mn_0.1)₂P₂O₇. The second phosphor may be a blue-green emitting Eu²⁺ doped SAE, (Sr_0.90-0.99Eu_0.01-0.1)₄Al₁₄O₂₅. A human observer perceives the combination of the orange and the blue-green phosphor emissions as white light.

Claims

1. A white light illumination system comprising:

a radiation source;

a first luminescent material having a peak emission wavelength of about 570 to about 620 nm, the first luminescent material comprising a first APO;

Eu²⁺,Mn²⁺ phosphor; and

a second luminescent material having a peak emission wavelength of about 480 to about 500 nm, which is different from the first luminescent material,

wherein A comprises at least one of Sr, Ca, Ba or Mg.

2. The system of claim 1, wherein the first phosphor comprises A₂P₂O₇:

Eu²⁺,Mn²⁺.

3. The system of claim 2, wherein:

the first phosphor comprises (A<sub>1−

x−

y</sub>Eu_xMn_y)₂P₂O₇;

0<

x≦

0.2; and

0<

y≦

0.2.

4. The system of claim 3, wherein the second luminescent material comprises a second phosphor selected from at least one of:

a) A₄D₁₄O₂₅;

Eu²⁺, where A comprises at least one of Sr, Ca, Ba or Mg, and D comprises at least one of Al or Ga;

b) (2AO*0.84P₂O₅*0.16B₂O₃);

Eu²⁺, where A comprises at least one of Sr, Ca, Ba or Mg;

c) AD₈O₁₃;

Eu²⁺, where A comprises at least one of Sr, Ca, Ba or Mg, and D comprises at least one of Al or Ga;

d) A₁₀(PO₄)₆Cl₂;

Eu²⁺, where A comprises at least one of Sr, Ca, Ba or Mg;

or

e) A₂Si₃O₈*2ACl₂;

Eu²⁺, where A comprises at least one of Sr, Ca, Ba or Mg.

5. The system of claim 4, wherein the second luminescent material comprises a second phosphor selected from at least one of:

a) a Sr₄Al₁₄O₂₅;

Eu²⁺ phosphor;

b) a (2SrO*0.84P₂O₅*0.16B₂O₃);

Eu²⁺ phosphor;

c) a BaAl₈O₁₃;

Eu²⁺ phosphor;

d) a (Sr,Mg,Ca)₁₀(PO₄)₆Cl₂;

Eu²⁺ phosphor;

or

e) a Sr₂Si₃O₈*2SrCl₂;

Eu²⁺ phosphor.

6. The system of claim 5, wherein the first phosphor and the second phosphor are interspersed.

7. The system of claim 6, wherein the light source comprises a light emitting diode having a peak emission wavelength of between 370 and 405 nm.

8. The system of claim 7, further comprising:

a shell containing the light emitting diode;

an encapsulating material between the shell and the light emitting diode;

and wherein;

a) the first and second phosphors are coated over a surface of the light emitting diode;

b) the first and second phosphors are interspersed in the encapsulating material;

or

c) the first and second phosphors are coated onto the shell.

9. The system of claim 8, wherein:

the first phosphor comprises (Sr_0.8Eu_0.1Mn_0.1)₂P₂O₇;

the second phosphor comprises (Sr_0.90-0.99Eu_0.01-0.1)₄Al₁₄O₂₅;

the light emitting diode peak emission wavelength is about 380 nm;

a ratio by weight of the first phosphor to the second phosphor is about 77;

23; and

CIE color coordinates of a radiation emitted by the system is about x=0.39 and y=0.42.

10. The system of claim 8, wherein:

the first phosphor comprises (Sr_0.8Eu_0.1Mn_0.1)₂P₂O₇;

the second phosphor comprises (Sr_0.90-0.99Eu_0.01-0.1)₄Al₁₄O₂₅;

the light emitting diode peak emission wavelength is about 405 nm;

the ratio by weight of the first phosphor to the second phosphor is about 89;

11; and

CIE color coordinates of a radiation emitted by the system is about x=0.39 and y=0.42.

11. A white light illumination system comprising:

a light emitting diode having a peak emission wavelength between 370 and 405 nm;

a first APO;

Eu²⁺,Mn²⁺ phosphor, where A comprises at least one of Sr, Ca, Ba or Mg; and

a second phosphor selected from at least one of;

a) A₄D₁₄O₂₅;

Eu²⁺, where A comprises at least one of Sr, Ca, Ba or Mg, and D comprises at least one of Al or Ga;

b) (2AO*0.84P₂O₅*0.16B₂O₃);

Eu²⁺, where A comprises at least one of Sr, Ca, Ba or Mg;

c) AD₈O₁₃;

Eu²⁺, where A comprises at least one of Sr, Ca, Ba or Mg, and D comprises at least one of Al or Ga;

d) A₁₀(PO₄)₆Cl₂;

Eu²⁺, where A comprises at least one of Sr, Ca, Ba or Mg;

or

e) A₂Si₃O₈*2ACl₂;

Eu²⁺, where A comprises at least one of Sr, Ca, Ba or Mg.

12. The system of claim 11, wherein:

the first phosphor comprises (A<sub>1−

x−

y</sub>Eu_xMn_y)₂P₂O₇, where 0<

x≦

0.2; and

0<

y<

0.2;

the second phosphor is selected from at least one of;

a) a Sr₄Al₁₄O₂₅;

Eu²⁺ phosphor;

b) a (2SrO*0.84P₂O₅*0.16B₂O₃);

Eu²⁺ phosphor;

c) a BaAl₈O₁₃;

Eu²⁺ phosphor;

d) a (Sr,Mg,Ca)₁₀(PO₄)₆Cl₂;

Eu²⁺ phosphor;

or

e) a Sr₂Si₃O₈*2SrCl₂;

Eu²⁺ phosphor; and

the first phosphor is interspersed with the second phosphor.

13. The system of claim 12, further comprising:

a shell containing the light emitting diode;

an encapsulating material between the shell and the light emitting diode;

and wherein;

a) the first and second phosphors are coated over a surface of the light emitting diode;

b) the first and second phosphors are interspersed in the encapsulating material;

or

c) the first and second phosphors are coated onto the shell.

14. The system of claim 13, wherein:

the first phosphor comprises (Sr_0.8Eu_0.1Mn_0.1)₂P₂O₇;

the second phosphor comprises (Sr_0.90-0.99 Eu_0.01-0.1)₄Al₁₄O₂₅;

CIE color coordinates of a radiation emitted by the system is about x=0.39 and y=0.42; and

the light emitting diode peak emission wavelength and a ratio by weight of the first phosphor to the second phosphor satisfy one of the following relationships;

a) the light emitting diode peak emission wavelength is about 380 nm and a ratio by weight of the first phosphor to the second phosphor is about 77;

23;

or

b) the light emitting diode peak emission wavelength is about 405 nm and a ratio by weight of the first phosphor to the second phosphor is about 89;

11.