Lighting systems for general illumination and disinfection
Lighting systems combine UV-A and white light with an adjustable CCT value so that any adverse effects from the UV-A radiation are mitigated—that is, tunable adjustments to the output of the non-UV LEDs, or to all of the LEDs, result in an overall mixed output conforming to a target CCT value.
1. A lighting device producing visible light and UV-A radiation, the lighting device comprising:
a plurality of UV-A LEDs emitting UV radiation having a wavelength between approximately 315 nm and approximately 420;
at least one photo-luminescent material configured to shift a color correlated temperature (CCT) value a portion of the UV radiation emitted by the UV-A LEDs toward a green CCT value and/or a yellow CCT value; and
a waveguide material having (i) a mixing region for mixing the shifted light and unshifted UV radiation, thereby forming mixed light, and (ii) an output region for outputting the mixed light.
2. The lighting device of claim 1 , wherein the UV-A LEDs have an emission peak at 395 nm.
3. The lighting device of claim 1 , wherein the at least one photo-luminescent material comprises at least one of a phosphor, a quantum dot material, or a fluorescent dye.
4. The lighting device of claim 1 , wherein the at least one photo-luminescent material has an emission peak between 500 nm and 600 nm.
5. The lighting device of claim 1 , wherein the UV-A LEDs are encapsulated within the waveguide material.
6. The lighting device of claim 1 , wherein the waveguide material comprises silicone.
7. The lighting device of claim 1 , further comprising a plurality of red LEDs emitting red light having a wavelength between approximately 600 nm and approximately 670 nm, and/or a plurality of blue LEDs emitting blue light having a wavelength between approximately 440 nm and approximately 485 nm.
8. The lighting device of claim 7 , wherein the mixed light comprises white light and UV radiation.
9. The lighting device of claim 7 , wherein the at least one photo-luminescent material is configured to shift a CCT value of the red LEDs and/or the blue LEDs.
10. The lighting device of claim 1 , further comprising control circuitry for adjusting a parameter associated with at least one of the UV-A LEDs.
11. The lighting device of claim 10 , wherein the parameter comprises at least one of an amplitude or a duty cycle of a current or a voltage associated with the UV-A LEDs.
12. The lighting device of claim 10 , wherein the UV-A LEDs are electrically configured in a plurality of groups, and the control circuitry is configured to adjust each of the groups individually.
13. The lighting device of claim 1 , further comprising a plurality of cup-shaped reflectors for at least partial collimation of light emitted from the UV-A LEDs, wherein each reflector has a top aperture and a bottom aperture and the bottom aperture has one of the UV-A LEDs disposed therein.
14. The lighting device of claim 13 , wherein at least one of the reflectors is a parabolic reflector, the respective UV-A LED disposed therein being located at or near the focus of the parabolic reflector.
15. The lighting device of claim 13 , further comprising an encapsulant material filled in a cavity space above one of the plurality of UV-A LEDs and surrounded by the respective reflector.
16. The lighting device of claim 13 , wherein the reflectors comprise or consist essentially of silicone.
17. The lighting device of claim 1 , further comprising a circuit board for mounting the UV-A LEDs thereon.
18. The lighting device of claim 17 , further comprising a heat-dissipation structure thermally coupled to the circuit board for dissipating heat generated by the plurality of UV-A LEDs.
19. The lighting device of claim 1 , further comprising at least one reflector located in the mixing region of the waveguide for promoting mixing of light.
20. The lighting device of claim 1 , wherein the at least one photo-luminescent material has an emission spectrum having a local minimum between 350 nm and 400 nm.