Solid state lighting fixture with incandescent dimming characteristics
View Patent ↗A dimmable LED lighting system includes first, second and third types of LED light sources, and an LED driver to control the supply of current on first, second and third channels, respectively to the first, second and third types of LED light sources. The first, second and third types of LED light sources are selected according to their spectral power distribution (SPD) curves. The selected SPD curves together model a dimming color curve that is characteristic of an incandescent light source when the first, second and third types of LED light sources are separately driven with current at predefined power ratios that correspond to dimming levels over a dimming region of the dimming color curve. The dimmable LED lighting system can have a color rendering index R a greater than 80 over the dimming region.
1. A dimmable LED lighting system comprising:
a first LED light source;
a second LED light source;
a third LED light source, wherein:
the first LED light source, the second LED light source, and third LED light source are selected with different spectral power distribution (SPD) curves;
the first, second, and third LED light sources have the following properties:
1.63≦γ 1 ≦1.79 for the first LED light source,
3.6≦γ 2 ≦3.8 for the second LED light source, and
10.2≦γ 3 ≦11.6 for the third LED light source,
where S(λ) is a function of spectral power versus a wavelength of an LED light source,
I 1 is {Max[S(λ)]} in a wavelength range of 400 to 500 nm,
I 2 is {Min[S(λ)]} in a wavelength range of 420 to 550 nm,
I 3 is {Max[S(λ)]} in a wavelength range of 500 to 700 nm,
γ 1 =I 3 /I 1 for the first LED light source,
γ 2 =I 3 /I 1 for the second LED light source, and
γ 3 =I 3 /I 1 for the third LED light source; and
the selected SPD curves together modeling a dimming color curve that is characteristic of an incandescent light source when the first LED light source, the second LED light source, and the third LED light source are driven on a first channel, a second channel, and a third channel, respectively, at predefined power ratios that correspond to dimming levels over a dimming region of the dimming color curve; and
an LED driver to control current supply on the first channel, the second channel, and the third channel to the first LED light source, the second LED light source, and the third LED light sources, respectively, at a power ratio from the predefined power ratios according to a selected dimming level, wherein a color rendering index is 90 or greater over the dimming region of the dimming color curve for a combination of the first LED light source, the second LED light source, and the third LED light source.
2. The dimmable LED lighting system of claim 1 , wherein the dimming color curve is defined by the following equation:
CCT=2920+396 ln( x )+88.7 ln( x ) 2 +11.6 ln( x ) 3
where CCT is a color correlated temperature, and
x is a dim percentage.
3. The dimmable LED lighting system of claim 1 , wherein the first, second, and third LED light sources and their associated first, second, and third channels have the following properties:
20≦α 1 ≦35 and 35≦β 1 ≦58 for the first LED light source on the first channel,
12.8≦α 2 ≧17.85 and 46≦β 2 ≦66 for the second LED light source on the second channel, and
7.7≦α 3 ≦13.7 and 80≦β 3 ≦155 for the third LED light source on the third channel,
where
α 1 =I 1 /I 2 and β 1 =I 3 /I 2 for the first LED light source on the first channel,
α 2 =I 1 /I 2 and β 2 =I 3 /I 2 for the second LED light source on the second channel, and
α 3 =I 1 /I 2 and β 3 =I 3 /I 2 for the third LED light source on the third channel.
4. The dimmable LED lighting system of claim 3 , wherein
(1) α 1 =25, β 1 =42, or γ 1 =1.73,
(2) α 2 =15, β 2 =55, or γ 2 =3.65, or
(3) α 3 =9.5, β 3 =103, or γ 3 =10.8.
5. The dimmable LED lighting system of claim 1 , wherein the first, second, and third LED light sources and their associated first, second, and third channels have the following properties:
α 1 :α 2 :α 3 =(from 2.3 to 3.8):(from 1.2 to 2.1):1,
β 1 :β 2 :β 3 =(from 0.35 to 0.52):(from 0.41 to 0.72):1, and
γ 1 :γ 2 :γ 3 =(from 0.13 to 0.17):(from 0.31 to 0.36):1,
where
α 1 =I 1 /I 2 and β 1 =I 3 /I 2 for the first LED light source,
α 2 =I 1 /I 2 and β 2 =I 3 /I 2 for the second LED light source, and
α 3 =I 1 /I 2 and β 3 =I 3 /I 2 and for the third LED light source.
6. The dimmable LED lighting system of claim 1 , wherein the first LED light source, the second LED light source, and the third LED light source and their associated first, second, and third channels have the following properties:
20≦α 1 ≦35 and 35≦β 1 ≦58 for the first LED light source,
7.7≦α 2 ≦13.7, 80<β 2 ≦155, and 10.2≦γ 2 ≦11.6 for the second LED light source,
where
α 1 =I 1 /I 2 and β 1 =I 3 /I 2 for the first LED light source, and
α 2 =I 1 /I 2 and β 2 =I 3 /I 2 for the second LED light source.
7. The dimmable LED lighting system of claim 1 , wherein a color rendering index Ra is greater than 90 over the dimming region of the dimming color curve for the combination of the first LED light source, the second LED light source, and the third LED light source with one of the first LED light source, the second LED light source, and the third LED light source on one channel having an Ra greater than 90 and the other two of the first, second, and third LED light sources on the other channels having an Ra equal to or less than 90.
8. The dimmable LED lighting system of claim 1 , wherein:
the first LED light source has a first color temperature of between 2900 Kelvin and 3100 Kelvin,
the second LED light source has a second color temperature between 2200 Kelvin and 2400 Kelvin, and
the third LED light source has a third color temperature between 1750 Kelvin and 1850 Kelvin.
9. A method of operating an LED lighting system comprising:
providing:
a first LED light source;
a second LED light source; and
a third LED light source, wherein:
each of the first LED light source, the second LED light source, and the third LED light sources are selected with different spectral power distribution (SPD) curves;
the first, second, and third LED light sources have the following properties:
1.63≦γ 1 ≦1.79 for the first LED light source,
3.6≦γ 2 ≦3.8 for the second LED light source, and
10.2≦γ 3 ≦11.6 for the third LED light source,
where S(λ) is a function of spectral power versus a wavelength of an LED light source,
I 1 is {Max[S(λ)]} in a wavelength range of 400 to 500 nm,
I 2 is {Min[S(λ)]} in a wavelength range of 420 to 550 nm,
I 3 is {Max[S(λ)]} in a wavelength range of 500 to 700 nm,
γ 1 =I 3 /I 1 for the first LED light source,
γ 2 =I 3 /I 1 for the second LED light source, and
γ 3 =I 3 /I 1 for the third LED light source; and
the selected SPD curves together model a dimming color curve that is characteristic of an incandescent light source when the first LED light source, the second LED light source, and the third LED light sources are driven on first, second, and third channels, respectively, at predefined power ratios that correspond to predefined dimming levels over a dimming region of the dimming color curve; and
controlling current supply on the first, second, and third channels to the first LED light source, the second LED light source, and the third LED light source respectively at a power ratio from the predefined power ratios according to a selected dimming level, wherein a color rendering index is 80 or greater over the dimming region of the dimming color curve for a combination of the first LED light source, the second LED light source, and the third LED light source.
10. The method of claim 9 , wherein the dimming color curve is defined by the following equation:
CCT=2920+396 ln( x )+88.7 ln( x ) 2 +11.6 ln( x ) 3
where CCT is a color correlated temperature, and
x is a dim percentage.
11. The method of claim 9 , wherein the first LED light source, the second LED light source, and the third LED light sources and their associated first, second, and third channels have the following properties:
20≦α 1 ≦35 and 35≦β 1 ≦58 for the first LED light source on the first channel,
12.8≦α 2 17.85 and 46≦β 2 ≦66 for the second LED light source on the second channel, and
7.7≦α 3 ≦13.7 and 80≦β 3 ≦155 for the third LED light source on the third channel,
where
α 1 =I 1 /I 2 and β 1 =I 3 /I 2 for the first LED light source on the first channel,
α 2 =I 1 /I 2 and β 2 =I 3 /I 2 for the second LED light source on the second channel, and
α 3 =I 1 /I 2 and β 3 =I 3 /I 2 for the third LED light source on the third channel.
12. The method of claim 11 , wherein
α 1 =25, β 1 =42, or γ 1 =1.73 on the first channel,
α 2 =15, β 2 =55, or γ 2 =3.65 on the second channel, or
α 3 =9.5, β 3 =103, or γ 3 =10.8 on the third channel.
13. The method of claim 9 , wherein the first, second, and third LED light sources and their associated first, second, and third channels have the following properties:
α 1 :α 2 :α 3 =(from 2.3 to 3.8):(from 1.2 to 2.1):1,
β 1 :β 2 :β 3 =(from 0.35 to 0.52):(from 0.41 to 0.72):1, and
γ 1 :γ 2 :γ 3 =(from 0.13 to 0.17):(from 0.31 to 0.36):1,
where
α 1 =I 1 /I 2 and β 1 =I 3 /I 2 for the first LED light source on the first channel,
α 2 =I 1 /I 2 and β 2 =I 3 /I 2 for the second LED light source on the second channel, and
α 3 =I 1 /I 2 and β 3 =I 3 /I 2 for the third LED light source.
14. The method of claim 9 , wherein the first, second, and third LED light sources and their associated first, second, and third channels have the following properties:
20≦α 1 ≦35 and 35≦β 1 ≧58 for the first LED light source,
7.7≦α 2 13.7 and 80≦β 2 ≦155 for the second LED light source
where
α 1 =I 1 /I 2 , β 1 =I 3 /I 2 and γ 1 =I 3 /I 1 on the first channel, and
α 2 =I 1 /I 2 and β 2 =I 3 /I 2 on the second channel.
15. The method of claim 9 , wherein a color rendering index Ra is greater than 90 over the dimming region of the dimming color curve for the combination of the first, second, and third LED light sources with one of the first, second, and third LED light sources on one channel having an Ra greater than 90 and the other two of the first, second, and third LED light sources on the other channels having an Ra equal to or less than 90.
16. The method of claim 9 , further comprising:
updating the predefined power ratios configured on the LED driver.
17. The method of claim 9 , wherein controlling current supply on the first, second, and third channels includes decreasing current on the first channel while increasing the current on the second channel and/or the third channel while dimming the LED lighting system.
18. A method of manufacturing an LED lighting system comprising:
selecting a first LED light source, a second LED light source, and a third LED light source, wherein:
each of the first, second, and third LED light sources are selected with different spectral power distribution (SPD) curves;
a first SPD curve:
defines the spectral power distribution of the first LED light source; and
comprises a first local maximum, a second local maximum, and a local minimum;
the local minimum of the first SPD curve is between the first local maximum of the first SPD curve of and the second local maximum of the first SPD curve;
a second SPD curve:
defines the spectral power distribution of the second LED light source; and
comprises a first local maximum, a second local maximum, and a local minimum;
the local minimum of the second SPD curve is between the first local maximum of the second SPD curve and the second local maximum of the second SPD curve; and
the first, second, and third LED light sources have the following properties:
1.63≦γ 1 ≦1.79 for the first LED light source,
3.6≦γ 2 ≦3.8 for the second LED light source, and
10.2≦γ 3 ≦11.6 for the third LED light source,
where S(λ) is a function of spectral power versus a wavelength of an LED light source,
I 1 is {Max[S(λ)]} in a wavelength range of 400 to 500 nm,
I 2 is {Min[S(λ)]} in a wavelength range of 420 to 550 nm,
I 3 is {Max[S(λ)]} in a wavelength range of 500 to 700 nm,
γ 1 =I 3 /I 1 for the first LED light source,
γ 2 =I 3 /I 1 for the second LED light source, and
γ 3 =I 3 /I 1 for the third LED light source; and
the selected SPD curves together modeling a dimming color curve that is characteristic of an incandescent light source when the first, second, and third LED light sources are driven on first, second, and third channels, respectively, at predefined power ratios that correspond to predefined dimming levels over a dimming region of the dimming color curve; and
configuring an LED driver to control the supply of current on the first, second, and third channels to the first, second, and third LED light sources respectively at a power ratio from the predefined power ratios according to a selected dimming level, wherein:
a highest dimming level generates a color temperature less than 3200 Kelvin on the dimming color curve and a lowest dimming level generates a color temperature of more than 1750 Kelvin on the dimming color curve, and
a color rendering index is 80 or greater over the dimming region of the dimming color curve for a combination of the first LED light source, the second LED light source, and the third LED light source.
19. The method of claim 18 , wherein the first, second, and third LED light sources and their associated first, second, and third channels have the following properties:
20≦α 1 ≦35 and 35≦β 1 ≦58 for the first LED light source,
12.8≦α 2 ≦17.85 and 46≦β 2 ≦66 for the second LED light source, and
7.7≦α 3 ≦13.7 and 80<β 3 ≦155 for the third LED light source,
where
α 1 =I 1 /I 2 and β 1 =I 3 /I 2 for the first LED light source,
α 2 =I 1 /I 2 and β 2 =I 3 /I 2 for the second LED light source, and
α 3 =I 1 /I 2 , β 3 =I 3 /I 2 and γ 3 =I 3 /I 1 for the first LED light source.
20. The method of claim 18 , wherein the first LED light source, the second LED light source, and the third LED light sources and their associated first, second, and third channels have the following properties:
20≦α 1 ≦35 and 35≦β 1 ≧58 for the first LED light source,
7.7≦α 2 ≦13.7 and 80≦β 2 ≦155 for the second LED light source, and
the third LED light source is an amber LED light source,
where
α 1 =I 1 /I 2 and β 1 =I 3 /I 2 for the first LED light source and
α 2 =I 1 /I 2 and β 2 =I 3 /I 2 for the second LED light source.