Enhanced color-preference LED light sources using yag, nitride, and PFS phosphors
View Patent ↗Aspects of the present disclosure are directed to a composite light source which includes at least one blue light source having peak wavelength in the range of about 400 nm to about 460 nm; at least one yellow-green garnet phosphor; and at least one narrow-band red-emitting down-converter. Such composite light source may have a Lighting Preference Index (LPI) of at least 120. In other aspects the disclosure is directed to composite light source comprising at least one blue light source having peak wavelength in the range of about 400 nm to about 460 nm; at least one yellow-green garnet phosphor; and at least one broad red down-converter. In this latter aspect the composite light source may have a Lighting Preference Index (LPI) of at least 120. Numerous other aspects are provided.
1. A composite light source comprising:
at least one blue light source having peak wavelength in the range of about 400 nanometer (nm) to about 460 nm;
at least one yellow-green garnet phosphor; and
at least one narrow red down-converter having a full-width at half maximum<about 60 nm;
wherein the composite light source has a Lighting Preference Index (LPI) of at least 120 and the LPI is defined by the following equation:
LPI= 100+19×[1−100√{square root over (( Duv+ 0.010) 2 )}]+0.62×[ NSV−HDV/ 2.5]
where Duv is a distance of a color point from Planckian locus in u-v space, NSV is Net Saturation Value of an illumination source, and HDV is Hue Distortion Value.
2. The composite light source of claim 1 , wherein the LPI is at least 140.
3. The composite light source of claim 1 , wherein the at least one narrow red down-converter light source has a peak wavelength in the range of about 610 nm and about 660 nm.
4. The composite light source of claim 1 , wherein the at least one yellow-green garnet phosphor has a full-width at half-maximum (FWHM) in the range from about 110 nm to about 115 nm.
5. The composite light source of claim 1 , wherein the narrow red down-converter is a manganese-doped potassium fluoro-silicate (PFS).
6. The composite light source of claim 1 , wherein the narrow red down-converter is PFS, the at least one yellow-green garnet phosphor is a YAG:Ce phosphor, the YAG:Ce phosphor has a dominant wavelength in the range from about 559 nm to about 572 nm, and Duv is in the range from about −0.002 to −0.016.
7. The composite light source of claim 1 , wherein the narrow red down-converter is PFS, the at least one yellow-green garnet phosphor is a YAG:Ce phosphor, the YAG:Ce phosphor has a dominant wavelength in the range from about 559 nm to about 563 nm, and Duv is in the range from about −0.008 to about −0.012.
8. The composite light source of claim 1 , wherein the composite light source emits a color spectrum including a blue wavelength range portion emitted by the blue light source, a yellow wavelength range portion emitted by the yellow-green garnet phosphor, and a red wavelength range portion emitted by the narrow red down-converter; and wherein the color spectrum includes a depression in the yellow wavelength range portion compared to a blackbody spectrum, wherein the depression in the yellow wavelength range portion is about 570 nm to 600 nm.
9. The composite light source of claim 1 , further comprising a neodymium filter placed over the at least one blue light source, the at least one yellow-green garnet phosphor, and the at least one narrow red down-converter, such that most or all of the light emitted by the composite light source passes through the filter.
10. A composite light source comprising:
at least one blue light source having peak wavelength in the range of about 400 nanometer (nm) to about 460 nm;
at least one YAG:Ce phosphor; and
at least one narrow red down-converter having a full-width at half-maximum (FWHM)<about 60 nm;
wherein a color appearance of the composite light source is represented as
Dom
YAG
<
13.3
1
-
(
Duv
+
.0095
.0070
)
2
+
569.8
-
0.004
*
CCT
,
where Duv is a measure of the whiteness of the composite light source and Dom YAG is the dominant wavelength of the at least one YAG:Ce phosphor.
11. The composite light source of claim 10 , further comprising at least one yellow-green garnet phosphor different from the YAG:Ce phosphor.
12. The composite light source of claim 10 , wherein the narrow red down-converter is manganese-doped potassium fluoro-silicate (PFS).
13. The composite light source of claim 10 , wherein the composite light source emits a color spectrum including a blue wavelength range portion emitted by the blue light source, a yellow wavelength range portion emitted by the YAG:Ce phosphor, and a red wavelength range portion emitted by the narrow red down-converter; and wherein the color spectrum includes a depression in the yellow wavelength range portion compared to a blackbody spectrum, wherein the depression in the yellow wavelength range portion is about 570 nm to 600 nm.
14. A composite light source comprising:
at least one blue light source having peak wavelength in the range of about 400 nanometer (nm) to about 460 nm;
at least one yellow-green garnet phosphor; and
at least one broad red down-converter having a full-width at-half maximum (FWHM)>about 60 nm;
wherein the composite light source has a Lighting Preference Index (LPI) of at least 120 and the LPI is defined by the following equation:
LPI= 100+19×[1−100√{square root over (( Duv+ 0.010) 2 )}]+0.62×[ NSV−HDV/ 2.5]
where Duv is a distance of a color point from Planckian locus in u-v space, NSV is Net Saturation Value of an illumination source, and HDV is Hue Distortion Value.
15. The composite light source of claim 14 , wherein the LPI is at least 140.
16. The composite light source of claim 14 , wherein the at least one yellow-green garnet phosphor has a dominant wavelength in the range from about 559 nm to about 574 nm.
17. The composite light source of claim 14 , wherein the at least one yellow-green garnet phosphor is a YAG:Ce phosphor.
18. The composite light source of claim 14 , wherein the broad red down-converter is a broad red nitride phosphor.
19. The composite light source of claim 14 , wherein the broad red down-converter is a broad red nitride with a peak wavelength in the range from about 630 nm to about 680 nm, the YAG:Ce phosphor has a dominant wavelength in the range from about 559 nm to about 573 nm, and Duv is in the range from about 0.000 to −0.019.
20. The composite light source of claim 14 , wherein the composite light source emits a color spectrum including a blue wavelength range portion emitted by the blue light source, a yellow wavelength range portion emitted by the yellow-green garnet phosphor, and a red wavelength range portion emitted by the broad red down-converter; and wherein the color spectrum includes a depression in the yellow wavelength range portion compared to a blackbody spectrum, wherein the depression in the yellow wavelength range portion is about 570 nm to 600 nm.
21. The composite light source of claim 14 , further comprising a neodymium filter placed over the at least one blue light source, the at least one yellow-green garnet phosphor, and the at least one broad red down-converter, such that most or all of the light emitted by the composite light source passes through the filter.
22. A composite light source comprising:
at least one blue light source having peak wavelength in the range of about 400 nanometer (nm) to about 460 nm;
at least one YAG:Ce phosphor; and
at least one broad red nitride phosphor;
wherein a color appearance of the composite light source is represented as
Dom
YAG
<
(
-
0.155
(
Peak
Nit
-
630
)
+
2.91
Peak
Nit
-
630
+
1.6
)
1
-
(
Duv
+
.0099
-
.00001
*
(
Peak
Nit
-
630
)
0.0001
(
Peak
Nit
-
630
)
+
0.0014
Peak
Nit
-
630
-
0.0010
)
2
+
569.8
-
0.004
*
CCT
,
where Duv is a measure of the whiteness of the composite light source, Peak Nit is the peak wavelength of the at least one broad red nitride phosphor, and Dom YAG is the dominant wavelength of the at least one YAG:Ce phosphor.
23. The composite light source of claim 22 , further comprising at least one yellow-green garnet phosphor different from the YAG:Ce phosphor.
24. The composite light source of claim 22 , wherein the broad red nitride phosphor is represented by a general formula, CaAlSiN 3 :Eu 2+ .
25. The composite light source of claim 22 , wherein the broad red nitride phosphor has a peak wavelength in the range from about 630 nm to about 680 nm, the YAG:Ce phosphor has a dominant wavelength in the range from about 559 nm to about 573 nm, and Duv is in the range from about 0.000 to −0.019.
26. The composite light source of claim 22 , wherein the composite light source has a correlated color temperature (CCT) in the range of about 2500 Kelvin (K) to about 3200 K.
27. A composite light source comprising:
at least one blue light source having peak wavelength in the range of about 400 nanometer (nm) to about 460 nm;
at least one yellow-green garnet phosphor;
at least one narrow red down-converter having a full-width at half-maximum (FWHM)<about 60 nm; and
at least one broad red down-converter having a full-width at-half maximum (FWHM)>about 60 nm;
wherein the composite light source has a Lighting Preference Index (LPI) of at least 120 and the LPI is defined by the following equation:
LPI= 100+19×[1−100√{square root over (( Duv+ 0.010) 2 )}]+0.62×[ NSV−HDV/ 2.5]
where Duv is a distance of a color point from Planckian locus in u-v space, NSV is Net Saturation Value of an illumination source, and HDV is Hue Distortion Value.
28. The composite light source of claim 27 , wherein the narrow red down-converter is PFS.
29. The composite light source of claim 27 , wherein the broad red down-converter is a broad red nitride phosphor.
30. The composite light source of claim 27 , wherein the narrow red down-converter is PFS, the broad red down-converter is a broad red nitride phosphor with a peak wavelength in the range from about 620 nm to about 680 nm, the YAG:Ce phosphor has a dominant wavelength in the range from about 559 nm to about 572 nm, and Duv is in the range from about 0.000 to −0.018.
31. The composite light source of claim 27 , wherein the narrow red down-converter is PFS, the broad red down-converter is a broad red nitride phosphor with a peak wavelength in the range from about 660 nm to about 680 nm, the YAG:Ce phosphor has a dominant wavelength in the range from about 559 nm to about 566 nm, and Duv is in the range from about −0.008 to about −0.012.