Lighting system having reduced melanopic spectral content
View Patent ↗A disclosed light-emitting device may provide white light with a cyan gap coinciding with a melanopic sensitivity range and thus having reduced melanopic content. The disclosed light-emitting device may include a light source providing violet or blue light with a peak wavelength under 450 nanometers (nm). The disclosed light-emitting device may include at least one down-converter coupled to and located downstream of the light source and configured with a long-wavelength onset to convert the spectrum of the violet or blue light to generate white light with a spectral power content in a 447-531 nm wavelength range that is less than or equal to 10% of a total spectral power content in a 380-780 nm wavelength range. The disclosed light-emitting device may be incorporated in a light engine system that further includes a control system that controls a drive current to the light-emitting device.
1. A light-emitting device configured to provide white light with a cyan gap coinciding with a melanopic sensitivity range, the light-emitting device comprising:
a light source configured to provide violet or blue light with a peak wavelength under 450 nanometers (nm); and
at least one down-converter coupled to and located downstream of the light source and configured with a long-wavelength onset to convert a spectrum of the violet or blue light to generate the white light with a correlated color temperature (CCT) greater than or equal to 2700 Kelvin (K) and with a spectral power content in a 447-531 nm wavelength range that is less than or equal to 10% of a total spectral power content in a 380-780 nm wavelength range.
2. The light-emitting device of claim 1 , wherein the light source is configured to provide the violet or blue light with the peak wavelength between 410 nm and 420 nm.
3. The light-emitting device of claim 1 , wherein the light source is configured to provide the violet or blue light with the peak wavelength between 420 nm and 430 nm.
4. The light-emitting device of claim 1 , wherein the light source is configured to provide the violet or blue light with the peak wavelength between 430 nm and 440 nm.
5. The light-emitting device of claim 1 , wherein the light source is configured to provide the violet or blue light with the peak wavelength between 440 nm and 450 nm.
6. The light-emitting device of claim 1 , wherein the light source is configured as a short-wavelength pump phosphor-converted light-emitting diode (pc-LED).
7. The light-emitting device of claim 6 , wherein the pc-LED is a high-power flip-chip die.
8. The light-emitting device of claim 7 , wherein the at least one down-converter is a ceramic plate attached to the high-power flip-chip die.
9. The light-emitting device of claim 1 , wherein the at least one down-converter is a nitride-based phosphor system with peak emission in an amber wavelength range.
10. The light-emitting device of claim 9 , wherein the nitride-based phosphor system is made from at least one of the following materials: (Ba,Sr) 2 Si 5 N 8 :Eu (BSSN) or (Sr,Ca)SiAIN 3 :Eu (SCASN).
11. The light-emitting device of claim 1 , wherein the at least one down-converter is a phosphor coating.
12. The light-emitting device of claim 1 , wherein the at least one down-converter is a quantum dot converter.
13. The light-emitting device of claim 1 , wherein the at least one down-converter comprises a luminescent material that absorbs at least a part of the violet or blue light.
14. The light-emitting device of claim 1 , wherein the at least one down-converter comprises a luminescent material that transmits at least a part of the violet or blue light.
15. The light-emitting device of claim 1 , wherein the at least one down-converter is configured to provide a yellow light so that the light-emitting devices provides a broader combined emission spectrum extending into red light.
16. The light-emitting device of claim 1 , wherein the at least one down-converter is in contact with a light emitting surface of the light source.
17. The light-emitting device of claim 1 , wherein the at least one down-converter is located at a non-zero distance from a light emitting surface of the light source.
18. The light-emitting device of claim 1 implemented in a light engine that further includes a control system that controls a drive current to the light-emitting device.
19. A light engine configured to provide white light with tunable spectral content in a range coinciding with a melanopic sensitivity range, the light engine comprising:
a plurality of light-emitting devices, each of the plurality of light-emitting devices comprising:
a light source configured to provide violet or blue light with a peak wavelength under 450 nanometers (nm); and
at least one down-converter coupled to and located downstream of the light source and configured with a long-wavelength onset to convert a spectrum of the violet or blue light to generate the white light with a spectral power content in a 447-531 nm wavelength range that is less than or equal to 10% of a total spectral power content in a 380-780 nm wavelength range; and
a control system configured to control drive current to the plurality of light-emitting devices.