Patent ID: 7406110

Claim:
An apparatus for controlling the power of laser diodes, which generates control voltages during a non-imaging period and drives laser diodes using the control voltages during an imaging period, the apparatus comprising: an output voltage sensor, which senses output voltages of at least a first and second laser diode and outputs the output voltages to an optical power controller, wherein said output voltage sensor comprises an analog-to-digital converter, which converts an analog output voltage into a digital output voltage, and a calculator, which processes the digital output voltage and outputs a processing result to said optical power controller, wherein said calculator receives a digital output voltage of the second laser diode at every predetermined sampling cycle during the non-imaging period, averages the digital output voltage input of the second laser diode during each said predetermined sampling cycle, and outputs an average digital output voltage to said optical power controller; and the optical power controller, which generates control voltages for controlling the at least first and second laser diodes by performing a proportional-integral (PI) control on error voltages between reference voltages and the output voltages for first and second laser diodes received from the output voltage sensor during the non-imaging period, drives a first laser diode during the non-imaging period, and simultaneously drives the at least first and second laser diodes during the imaging period.