Patent ID: 6724793
Filing Date: 2004-04-20
Classification: G11B,H01S

Abstract:
A laser diode drive circuit for an optical disc recording and/or reproducing apparatus, comprising:a plurality of laser diodes for outputting laser beams having different wavelengths and different power output levels; a laser diode drive power supply circuit; a first switch circuit for selectively connecting a required laser diode from said plurality of laser diodes to said laser diode drive power supply circuit; a photodiode for detecting at least part of laser beams emitted from said laser diode to convert a detected part of laser beams into an electrical signal; a plurality of current-to-voltage conversion amplifiers connected to an output of said photodiode, being configured to adjust conversion resistance values and having different center conversion resistance values corresponding to respective said different power output levels of said plurality of laser diodes; and an automatic power control circuit connected by way of a second switch to outputs of said current-to-voltage conversion amplifiers to output a feedback signal to said laser diode drive power supply circuit.