US Patent 7403215 Current driver and power control for electrophotographic devices

Laser driver systems and methods are provided for controlling a laser driver coupled to a suitable laser source. The laser driver comprises a plurality of current sources, including at least one bias current source and at least two switched current sources. To control the laser driver, a laser power control signal is provided for each switched current source that corresponds to a desired laser output power. An output power error measure is defined based upon an error between a measured laser output power and the desired laser output power for each switched current source and a control system is characterized in which the output power error measures combine to change a magnitude of each of the switched current sources and the bias current source(s) such that the output power error measures converge over time.