System and method for selected pump LEDs with multiple phosphors
An LED pump light with multiple phosphors is described. LEDs emitting radiation at violet and/or ultraviolet wavelengths are used to pump phosphor materials that emit other colors. The LEDs operating in different wavelength ranges are arranged to reduce light re-absorption and improve light output efficiency.
1 . A light emitting system for emitting white light, said light emitting system comprising:
light emitting diodes (LEDs) comprising at least
a first set of LEDs comprising at least one first LED and emitting a first light having a first peak wavelength in a range 405-430 nm,
a second set of LEDs comprising at least one second LED and emitting a second light having a second peak wavelength which is longer than the first peak wavelength; and
wavelength-converting materials, configured to substantially absorb a portion of light from said LEDs and convert it to a third light and a fourth light;
wherein said white light comprises at least a portion of said first, second, third, and fourth lights.
2 . The system of claim 1 , wherein the second set of LEDs are blue LEDs.
3 . The system of claim 1 , wherein said wavelength-converting materials are disposed over one of the first or second sets of LEDs.
4 . The system of claim 1 , wherein said wavelength-converting materials comprises a green phosphor and a red phosphor.
5 . The system of claim 1 , wherein the wavelength-converting material does not include a blue phosphor.
6 . The system of claim 1 , wherein the first set of LEDs is characterized by an internal quantum efficiency of at least 70% when operated at a current density of 100 A·cm−2.
7 . The system of claim 1 , wherein said third light is green light and said fourth light is red light.
8 . The system of claim 1 , wherein said first and second lights are saturated and said third and fourth lights are unsaturated.