Methods, luminaires and systems for matching a composite light spectrum to a target light spectrum
View Patent ↗Methods, luminaires and systems for matching a composite light spectrum to a target light spectrum are disclosed. Method embodiments may be optimized for simultaneously maximizing luminous output with minimal chromaticity error. Method embodiments may further be optimized for simultaneously minimizing both chromaticity and spectral error. Embodiments of the present invention may be used with composite light sources having four or more distinct dominant colors within the visible spectrum.
1. A method of matching an output composite light spectrum to a target light spectrum, the method comprising:
providing a light emitting diode (LED) array, the LED array comprising emitters having four or more distinct dominant wavelengths within visible spectrum for generating the output composite light spectrum; and
simultaneously minimizing differences between CIE chromaticity coordinates and spectral differences between the target light spectrum and the output composite light spectrum,
wherein minimizing the differences between CIE chromaticity coordinates of the target light spectrum and the output composite light spectrum comprises minimizing a chromaticity error, E c , defined by:
E c =W (( x o −x t ) 2 +( y o −y t ) 2 ),
where x t ,y t , are CIE chromaticity coordinates of the target light spectrum, x o ,y o are CIE chromaticity coordinates of the output composite light spectrum, and W is a weighting factor.
2. The method according to claim 1 , wherein minimizing the differences between CIE chromaticity coordinates of the target light spectrum and the composite light spectrum, comprises:
(1) calculating the CIE chromaticity coordinates of the target light spectrum, x t ,y t , using at least one of: source color temperature, color standard and subject to be illuminated;
(2) calculating the CIE chromaticity coordinates of the output composite light spectrum, x o ,y o ;
(3) calculating a chromaticity error, E c , between the CIE chromaticity coordinates of the target light spectrum, x t ,y t , and the chromaticity coordinates of the output composite light spectrum, x o ,y o ; and
(4) adjusting mix coefficients of the emitters and recalculating steps (2) and (3) to minimize the chromaticity error, E c .
3. The method according to claim 1 , wherein minimizing the spectral differences between the target light spectrum and the output composite light spectrum, comprises minimizing a spectral error, E s , defined as:
E
s
=
∑
i
=
1
n
[
(
P
(
λ
i
)
-
F
(
λ
i
)
)
2
]
×
y
_
(
λ
i
)
,
is where P(λ) is the target light spectrum, F(λ) is the output composite light spectrum, and y (λ i ) is a CIE photopic function, calculated over n points across the visible spectrum.
4. A light emitting diode (LED) array including four or more distinct dominant wavelengths within visible spectrum configured for generating an output composite light spectrum matched to a preselected target light spectrum wherein the output composite light spectrum provides a spectral match between the target light spectrum and the output composite light spectrum having a chromaticity error,
wherein generating the output composite light spectrum matched to a preselected target light spectrum comprises minimizing the chromaticity error between the target light spectrum and the output composite light spectrum, and
wherein the chromaticity error, E c , is defined as:
E c =W (( x o −x t ) 2 +( y o −y t ) 2 ),
where x t ,y t , are CIE chromaticity coordinates of the target light spectrum, x o ,y o are CIE chromaticity coordinates of the output composite light spectrum, and W is a weighting factor.
5. The LED array according to claim 4 , wherein providing best spectral match between the target light spectrum and the output composite light spectrum comprises minimizing a spectral error between the target light spectrum and the output composite light spectrum.
6. The LED array according to claim 5 , wherein the spectral error is defined as:
E
s
=
∑
i
=
1
n
[
(
P
(
λ
i
)
-
F
(
λ
i
)
)
2
]
×
y
_
(
λ
i
)
,
where P(λ) is the target light spectrum, F(λ) is the output composite light spectrum, and y (λ i ) is a CIE photopic function, calculated over n points across the visible spectrum.
7. A light emitting diode (LED) array including four or more distinct dominant wavelengths within visible spectrum configured for generating an output composite light spectrum matched to a preselected target light spectrum wherein the output composite light spectrum provides a spectral match between the target light spectrum and the composite light spectrum having a spectral error, wherein the spectral error, E s , is defined as:
E
s
=
∑
i
=
1
n
[
(
P
(
λ
i
)
-
F
(
λ
i
)
)
2
]
×
y
_
(
λ
i
)
,
where P(λ) is the target light spectrum, F(λ) is the output composite light spectrum, and y (λ i ) is a CIE photopic function, calculated over n points across the visible spectrum.
8. The LED array according to claim 7 , wherein generating the output composite light spectrum matched to the preselected target light spectrum comprises minimizing a chromaticity error between the target light spectrum and the output composite light spectrum.
9. The LED array according to claim 8 , wherein the chromaticity error, E c , is defined as:
E c =W (( x o −x t ) 2 +( y o −y t ) 2 ),
where x t ,y t , are CIE chromaticity coordinates of the target light spectrum, x o ,y o are CIE chromaticity coordinates of the output composite light spectrum, and W is a weighting factor.
10. The LED array according to claim 7 , wherein providing the spectral match between the target light spectrum and the output composite light spectrum comprises minimizing the spectral error between the target light spectrum and the output composite light spectrum.