Solid state lighting fixture with incandescent dimming characteristics

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≦γ1≦1.79 for the first LED light source,
• 3.6≦γ2≦3.8 for the second LED light source, and
• 10.2≦γ3≦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,
• I1 is {Max[S(λ)]} in a wavelength range of 400 to 500 nm,
• I2 is {Min[S(λ)]} in a wavelength range of 420 to 550 nm,
• I3 is {Max[S(λ)]} in a wavelength range of 500 to 700 nm,
• γ1=I3/I1 for the first LED light source,
• γ2=I3/I1 for the second LED light source, and
• γ3=I3/I1 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.

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≦γ1≦1.79 for the first LED light source,
• 3.6≦γ2≦3.8 for the second LED light source, and
• 10.2≦γ3≦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,
• I1 is {Max[S(λ)]} in a wavelength range of 400 to 500 nm,
• I2 is {Min[S(λ)]} in a wavelength range of 420 to 550 nm,
• I3 is {Max[S(λ)]} in a wavelength range of 500 to 700 nm,
• γ1=I3/I1 for the first LED light source,
• γ2=I3/I1 for the second LED light source, and
• γ3=I3/I1 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.