US Patent No. 10,716,183

METHOD FOR WIDE-RANGE CCT TUNING THAT FOLLOWS THE BLACK BODY LINE USING TWO INDEPENDENTLY CONTROLLED CURRENT CHANNELS AND THREE CCTS


Patent No. 10,716,183
Issue Date July 14, 2020
Title Method For Wide-range Cct Tuning That Follows The Black Body Line Using Two Independently Controlled Current Channels And Three Ccts
Inventorship Frederic S. Diana, San Jose, CA (US)
Yifeng Qiu, San Jose, CA (US)
Assignee Lumileds LLC, San Jose, CA (US)

Claim of US Patent No. 10,716,183

2. A light-emitting diode (LED) lighting system comprising:an LED array configured to emit light having a first correlated color temperature (CCT) at a first end of a first range;
a second LED array configured to emit light having a second CCT at a second end of the first range;
a third LED array configured to emit light having a third CCT in a range between the first CCT and the second CCT;
a two-channel LED driver having two output terminals configured to provide a separate driving current at each of the two output terminals; and
a converter circuit having two input terminals, each of the two input terminals electrically coupled to a respective one of the two output terminals of the two-channel LED driver, and three output terminals, each of the three output terminals electrically coupled to a respective one of the first, second, and third LED arrays to provide a separate drive current to each of the first, second, and third LED arrays via respective first, second, and third drive channels, the converter circuit including:
a first computational circuit electrically coupled to receive a first voltage based on a first driving current of the two channel LED driver and configured to provide a first output voltage having a level equal to a level of the second input voltage minus a level of the first input voltage;
a second computational circuit electrically coupled to receive a second input voltage based on a second driving current of the two channel LED driver and configured to provide a second output voltage having a level equal to the level of the first input voltage minus the level of the second input voltage;
a first current generator configured to generate a first drive current having a level based on the level of the first output voltage;
a second current generator configured to generate a second drive current having a level based on the level of the second output voltage; and
a control circuit configured to provide a third drive current having a level based on the levels of the first and second input voltages on a condition that both the levels of the first and second input currents are greater than zero.