Efficient lighting system with wide color range

摘要

Broadband solid state light sources include remote phosphor LED(s), short-wavelength direct emitting LED(s), and long-wavelength direct emitting LED(s). A diffuse or clear cover member covers these LEDs. Each remote phosphor LED includes an LED, a phosphor layer, and a dichroic reflector. The light sources can provide a broadband output light over a wide color range, and can do so efficiently while energizing a high percentage or proportion of the total number of LEDs in the system. The broadband output may for example exhibit a color difference of at least 0.2 in CIE chromaticity units, and/or a correlated color temperature difference of at least 4000 or 5000 Kelvin, while energizing more than half, or at least 60%, or at least 70%, of the total number of LEDs. Numbers of LEDs can be replaced with effective numbers of LEDs if LEDs of substantially different sizes are included in the light source.

主权项

1. A lighting system for emitting broad band light, comprising:
a total number N of LEDs; and a light-transmissive cover member that covers the N LEDs and transmits the broad band light; wherein the N LEDs include:
a number N1 of pump LEDs, each pump LED configured as a remote phosphor LED, wherein the pump LED is combined with a dichroic reflector and a phosphor layer such that at least some light from the pump LED is reflected by the dichroic reflector onto the phosphor layer to cause the phosphor layer to emit phosphor light, the dichroic reflector also configured to substantially transmit the phosphor light;a number N2 of direct emitting short-wavelength LEDs having peak output wavelengths in a range from 400 to 500 nm, each short-wavelength LED disposed to emit at least some light that propagates from the short wavelength LED to the cover member without being substantially reflected by any dichroic reflector; anda number N3 of direct emitting long-wavelength LEDs having peak output wavelengths in a range from 600 to 700 nm, each long-wavelength LED disposed to emit at least some light that propagates from the long wavelength LED to the cover member without being substantially reflected by any dichroic reflector; wherein the pump LEDs, the direct emitting short wavelength LEDs, and the direct emitting long wavelength LEDs are respectively wired for independent electrical control; wherein the broad band light transmitted by the cover member has a color that is a function of which ones of the N LEDs are energized; wherein the N LEDs are configured such that the broad band transmitted light can have a first color associated with a first group of the N LEDs being energized, and a second color associated with a second group of the N LEDs being energized; and wherein the first and second colors have a color difference of at least 0.2 in CIE chromaticity units, and wherein the first and second groups of the N LEDs each involve energizing more than half of the N LEDs.