Patent ID: 8330393
Filing Date: 2012-12-11
Classification: H05B

Abstract:
1. A system for exciting multiple strings of light-emitting diodes (LEDs), comprising: a controller adapted to be coupled to at least two LED strings, each of which includes at least one LED; at least one light intensity sensor, each of said sensors arranged to produce an output which varies with the intensity of the light output produced by at least one of said LED strings; and a current monitoring circuit connected in series with said LED strings and arranged to monitor the current conducted by each of said LED strings; said controller arranged to receive said sensor outputs, said controller, said LED strings, and said current monitoring circuit and/or said at least one light intensity sensor forming a closed-loop feedback circuit such that said controller provides closed-loop control of the currents conducted by said LED strings by time-sequentially pulse-width modulating said currents in response to said sensor outputs one at a time such that each string conducts a desired current and/or such that desired light intensities are produced by said strings.