Circadian-friendly LED light source
Methods and apparatus for providing circadian-friendly LED light sources are disclosed. A light source is formed to include a first LED emission (e.g., one or more LEDs emitting a first spectrum) and a second LED emission (e.g., one or more LEDs emitting a second spectrum) wherein the first and second LED emissions are combined in a first ratio and in a second ratio such that while changing from the first ratio to the second ratio the relative circadian stimulation is varied while maintaining a color rendering index above 80.
1. A light emitter comprising:
one or more LEDs configured to emit LED light, said one or more LEDs comprising at least a violet LED configured to emit violet light with a peak wavelength around 405 nm;
at least one phosphor configured convert a fraction of said LED light to emit converted light; and
wherein said light emitter emits an emitted light comprising a combination of at least said converted light and a fraction of said LED light, said emitted light having a spectral power distribution (SPD), said SPD having a first power from 350 nm to 850 nm, and a second power from 400 nm to about 440 nm, wherein said second power is at least 15% of said first power, and wherein said SPD has a color rendering index (CRI) greater than 80, and an R9 greater than 0.
2. The light emitter of claim 1 , wherein said second power is at least 20% of said first power.
3. The light emitter of claim 1 , wherein said second power is at least 25% of said first power.
4. The light emitter of claim 1 , wherein said R9 is at least 50.
5. The light emitter of claim 1 , wherein said emitted light has a chromaticity within +/−five Du′v′ points of the Planckian locus.
6. The light emitter of claim 5 , wherein said emitted light has a chromaticity below the Planckian locus.
7. The light emitter of claim 1 , wherein said SPD has a CCT ranging from about 3000K to about 9000K.
8. The light emitter of claim 1 , wherein said SPD has a local peak corresponding to said violet light.
9. The light emitter of claim 1 , wherein said one or more LEDs also comprises at least one second LED to emit second light different from said violet light.
10. The light emitter of claim 9 , wherein said second light is blue light.
11. The light emitter of claim 9 , wherein said one or more LEDs are configured to operate in two or more modes, in a first mode, said violet LED and said second LED are driven at a first ratio relative to each other resulting in said emitted light, and in a second mode, said violet LED and said second LED are driven at a second ratio relative to each other resulting in second emitted light, wherein said second emitted light has a second SPD, said second SPD has a third power from 350 nm to 850 nm, a fourth power from 400 nm to about 440 nm, and a fifth power from 440 nm to 500 nm, wherein said fourth power is less than 10% of said third power.
12. The light emitter of claim 11 , wherein said fifth power is at least 10% of said third power.
13. The light emitter of claim 1 , wherein said at least one phosphor comprises two or more phosphors.
14. The light emitter of claim 1 , wherein said at least one phosphor is pumped by said violet light.
15. The light emitter of claim 1 , wherein said one or more LEDs also comprises at least one second LED to emit second light different from said violet light, wherein said at least one phosphor is pumped by said second light.