Enhanced color-preference LED light sources using lag, nitride, and PFS phosphors
According to some embodiments, a composite light source includes at least one blue light source having a peak wavelength in the range of about 400 nanometer (nm) to about 460 nm; at least one LAG phosphor; at least one narrow red down-converter; and wherein the composite light source has 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 a peak wavelength in the range of about 400 nanometer (nm) to about 460 nm;
at least one lutetium aluminum garnet (LAG) phosphor; and
at least one narrow 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√( 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 at least one narrow red down-converter light source has a peak wavelength in the range of about 610 nm and about 660 nm.
3. The composite light source of claim 1 , further comprising at least one green or yellow-green garnet phosphor different from the LAG phosphor.
4. The composite light source of claim 1 , wherein the at least one LAG phosphor has a full-width at half-maximum (FWHM) in the range from about 100 nm to about 110 nm.
5. The composite light source of claim 1 , wherein the narrow red down-converter is manganese-doped potassium fluoro-silicate (PFS) phosphor.
6. The composite light source of claim 5 , wherein the LAG phosphor has a dominant wavelength in the range from about 548 nm to about 566 nm, and Duv is in the range from about −0.002 to −0.018.
7. 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 green or yellow wavelength range portion emitted by the LAG 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.
8. The composite light source of claim 1 , wherein the composite light source has a correlated color temperature (CCT) in the range of about 2500 Kelvin (K) to about 3200 K.
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 LAG 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 a peak wavelength in the range of about 400 nanometer (nm) to about 460 nm;
at least one lutetium aluminum garnet (LAG) 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
LAG
-
566
+
0.004
*
C
C
T
)
2
<
324
(
1
-
(
Duv
+
0.0096
0.0065
)
2
)
,
where Duv is a measure of the whiteness of the composite light source and Dom LAG is the dominant wavelength of the at least one LAG phosphor.
11. The composite light source of claim 10 , further comprising at least one green or yellow-green garnet phosphor different from the LAG phosphor.
12. The composite light source of claim 10 , wherein the narrow red down-converter is manganese-doped potassium fluoro-silicate (PFS) phosphor.
13. The composite light source of claim 12 , wherein the LAG phosphor has a dominant wavelength in the range from about 548 nm to about 566 nm, and the Duv is in the range from about −0.002 to −0.018.
14. 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 green or yellow wavelength range portion emitted by the LAG 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.
15. A composite light source comprising:
at least one blue light source having a peak wavelength in the range of about 400 nanometer (nm) to about 460 nm;
at least one lutetium aluminum garnet (LAG) phosphor; and
at least one broad red down-converter 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.
16. The composite light source of claim 15 , further comprising at least one green or yellow-green garnet phosphor different from the LAG phosphor.
17. The composite light source of claim 15 , wherein the at least one LAG phosphor has a full-width at half-maximum (FWHM) in the range from about 100 nm to about 110 nm.
18. The composite light source of claim 15 , wherein the broad red down-converter is a red nitride phosphor.
19. The composite light source of claim 18 , wherein the red nitride has a peak wavelength in the range from about 630 nm to about 680 nm, the LAG phosphor has a dominant wavelength in the range from about 548 nm to about 566 nm, and Duv is in the range from about 0.000 to −0.020.
20. A composite light source comprising:
at least one blue light source having a peak wavelength in the range of about 400 nanometer (nm) to about 460 nm;
at least one lutetium aluminum garnet (LAG) phosphor;
at least one broad red down converter having a full-width at-half maximum (FWHM) >about 60 nm; and
wherein a color appearance of the composite light source is represented as
(
Dom
LAG
-
0.30
(
Peak
Nit
-
627
)
-
553.9
+
0.004
*
C
C
T
)
2
<
(
-
1.114
(
Peak
Nit
-
627
)
+
9.96
Peak
Nit
-
627
-
0.8
)
2
(
1
-
(
Duv
+
0.0096
-
0.00011
(
Peak
Nit
-
627
)
+
0.0020
Peak
Nit
-
627
-
0.0010
)
2
)
,
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 LAG is the dominant wavelength of the at least one LAG phosphor.
21. The composite light source of claim 20 , further comprising at least one green or yellow-green garnet phosphor different from the LAG phosphor.
22. The composite light source of claim 20 , wherein the at least one LAG phosphor has a dominant wavelength in the range from about 548 nm to about 566 nm.
23. The composite light source of claim 20 , wherein the broad red down converter is a red nitride phosphor having a peak wavelength in the range from about 630 nm to about 680 nm, the LAG phosphor having a dominant wavelength in the range from about 548 nm to about 566 nm, and Duv is in the range from about 0.000 to −0.020.
24. 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 lutetium aluminum garnet (LAG) phosphor;
at least one narrow red down-converter having a full-width at half-maximum (FWHM)<about 60 nm;
at least one red down converter having a full-width at-half maximum (FWHM) >about 60 nm; and
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.
25. The composite light source of claim 24 , wherein the LPI is at least 140.
26. The composite light source of claim 24 , wherein the narrow red down-converter is manganese-doped potassium fluoro-silicate (PFS) phosphor.
27. The composite light source of claim 24 , wherein the broad red down-converter is a red nitride phosphor.
28. The composite light source of claim 27 , wherein the red nitride phosphor is represented by a general formula, CaAlSiN 3 :Eu 2+ .
29. The composite light source of claim 24 , wherein the composite light source has a correlated color temperature (CCT) in the range of about 2500 Kelvin (K) to about 3200 K.