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Solid state lighting fixture with incandescent dimming characteristics

  • US 9,867,254 B2
  • Filed: 10/31/2014
  • Issued: 01/09/2018
  • Est. Priority Date: 10/31/2014
  • Status: Active Grant
First Claim
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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, and10.2≦

    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,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,γ

    1=I3/I1 for the first LED light source,γ

    2=I3/I1 for the second LED light source, andγ

    3=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 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.

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