Patent ID: 7567600

Claim:
A laser diode driver for an N-wavelength optical pickup which includes N laser light sources of the first to N laser diodes for emitting first to N laser beams, respectively, of differing wavelengths and one front monitor for monitoring the luminous emittance of the first to N laser beams comprising: a single current/voltage conversion amplifier for converting a monitor current monitored by the front monitor into a monitor voltage and outputting the voltage as a monitor output signal which is sent to an optical disc drive, a playing input signal and a selection signal being supplied from the optical disc drive; and a selective driving unit for selectively driving any one of the first to N laser diodes in response to selection signals, the current/voltage conversion amplifier being configured to be capable of selecting first to N monitor-voltage conversion gains corresponding to the first to N laser diodes, the selective driving unit comprising: a logic circuit receiving the selection signal and connected to control terminals of a first selector, an output terminal of the current/voltage conversion amplifier being connected to a fixed contact of the first selector, the first selector being operated to selectively drive any one of the first to N monitor-voltage conversion gains of the current/voltage conversion amplifier in response to the selection signal received by the logic circuit, wherein N is an integer which is two or more.