PHOSPHORS FOR WARM WHITE EMITTERS

• US 20140264402A1
• Filed: 03/15/2013
• Published: 09/18/2014
• Est. Priority Date: 05/12/2011
• Status: Active Grant

• Current Assignee: Ledengin, Inc. (Ams-Osram AG)
• Original Assignee: Ledengin, Inc. (Ams-Osram AG)
• Inventors: Mei, Zequn, Vu, Truc Phoung Thi
• Granted Patent: US 9,528,665 B2
• Time in Patent Office: Days
• US Class Current: 257/89
• CPC Class Codes: F21K 9/64 using wavelength conversion means distinct or spaced from the light-generating element, e.g. a remote phosphor layer
• CPC Class Codes: H01L 2933/0041 relating to wavelength conversion elements
• CPC Class Codes: H01L 33/504 Elements with two or more wavelength conversion materials
• CPC Class Codes: H05B 45/24 using electrical feedback from LEDs or from LED modules

Abstract

A method for fabricating light-emitting devices includes obtaining a plurality of light-emitting diode (LED) chips fabricated to emit blue light and preparing a phosphor-containing material comprising a matrix material having dispersed therein a mixture of a red phosphor and a green phosphor in a fixed ratio to each other. The method also includes disposing different thicknesses of the phosphor-containing material on different ones of the LED chips. The fixed ratio is chosen such that LED chips having different thicknesses of the phosphor-containing material emit light characterized by different points along the Planckian locus in a CIE chromaticity diagram.

Claims

1. A method for fabricating light-emitting devices, the method comprising:

obtaining a plurality of light-emitting diode (LED) chips fabricated to emit blue light;

preparing a phosphor-containing material comprising a matrix material having dispersed therein a mixture of a red phosphor and a green phosphor in a fixed ratio to each other; and

disposing different thicknesses of the phosphor-containing material on different ones of the LED chips,

wherein the fixed ratio is chosen such that LED chips having different thicknesses of the phosphor-containing material emit light characterized by different points along the Planckian locus in a CIE chromaticity diagram.

2. The method of claim 1, wherein the green phosphor has a peak emitting wavelength that is less than 550 nm.

3. The method of claim 1, wherein the green phosphor has a peak emitting wavelength that is less than 525 nm.

4. The method of claim 1, wherein the green phosphor has a peak emitting wavelength in a range from about 515 nm to about 518 nm.

5. The method of claim 1, wherein the phosphor-containing material has about 60-80 units of red phosphor and 390-430 units of green phosphor.

6. The method of claim 1, wherein the fixed ratio is a ratio of about one part of red phosphor to 5-7 parts of green phosphor by weight.

7. The method of claim 1, further comprising combining two or more of the LED chips covered with different thicknesses of the phosphor-containing material to make an LED emitter, which emits light characterized by a point along the Planckian locus in the CIE chromaticity diagram.

9. The method of claim 1, wherein the phosphor-containing material has about 60-80 units of red phosphor and 390-430 units of green phosphor.

10. The method of claim 1, wherein the fixed ratio is a ratio of about one part of red phosphor to 5-7 parts of green phosphor by weight.

8. A method for fabricating light-emitting devices, the method comprising:

obtaining a plurality of light-emitting diode (LED) chips fabricated to emit blue light;

preparing a phosphor-containing material comprising a matrix material having dispersed therein a mixture of a red phosphor and a green phosphor in a fixed ratio to each other; and

disposing different thicknesses of the phosphor-containing material on different ones of the LED chips,

wherein the fixed ratio is chosen such that LED chips having different thicknesses of the phosphor-containing material emit light characterized by an ellipse having a long axis substantially parallel to the Planckian locus in a CIE chromaticity diagram.

11. A plurality of light emitting devices, comprising:

a plurality of light-emitting-diode (LED) chips configured to emit blue light, wherein different ones of the LED chips have different thicknesses of a phosphor-containing material formed thereon, the phosphor-containing material comprising a matrix material having dispersed therein a mixture of a red phosphor and a green phosphor in a fixed ratio to each other, wherein a distribution of light emitted from the plurality of LED chips having different thicknesses of the phosphor-containing material is characterized by an ellipse having a long axis substantially parallel to the Planckian locus in a CIE chromaticity diagram.

12. The plurality of light emitting devices of claim 11, wherein the green phosphor has a peak emitting wavelength that is 525 nm or less.

13. The plurality of light emitting devices of claim 11, wherein the green phosphor has a peak emitting wavelength in a range from about 515 nm to about 518 nm.

14. The plurality of light emitting devices of claim 11, wherein the fixed ratio is a ratio of about one unit of red phosphor to 5-7 units of green phosphor.

15. A plurality of light emitting devices, comprising:

a first light-emitting device including a first amount of a wavelength-conversion material overlying a first light-emitting-diode (LED) chip configured to emit light of a first color; and

a second light-emitting device including a second amount of the wavelength-conversion material overlying a second light-emitting-diode (LED) chip configured to emit light of the first color, the second amount being different from the first amount;

wherein the wavelength-conversion material comprises a matrix material having dispersed therein a mixture of a first phosphor and a second phosphor in a fixed ratio to each other; and

wherein the fixed ratio is chosen such that the first light-emitting device and the first light-emitting device emit light characterized by different points along the Planckian locus in a CIE chromaticity diagram.

16. The plurality of light emitting devices of claim 15, further comprising a third light-emitting device including a third amount of the phosphor-containing material overlying a third light-emitting-diode (LED) chip configured to emit light of the first color, the third amount being different from the first amount and the second amount,

wherein light from the third light-emitting device is characterized by a third point along the Planckian locus in the CIE chromaticity diagram.

17. The plurality of light emitting devices of claim 15, wherein the first color is blue, the first phosphor is a red phosphor, and the second phosphor is a green phosphor.

18. The plurality of light emitting devices of claim 17, wherein the green phosphor has a peak emitting wavelength that is less than 550 nm.

19. The plurality of light emitting devices of claim 17, wherein the green phosphor has a peak emitting wavelength that is less than 525 nm.

20. The plurality of light emitting devices of claim 17, wherein the fixed ratio is a ratio of about one unit of red phosphor to 5-7 units of green phosphor.