Monitoring circuit for a light emission device

摘要

There is disclosed a monitoring circuit for a light emission device comprising; conversion circuit for converting a current flowing through a light emission device when a drive signal is applied thereto a voltage; shift adjustment circuit for producing shift adjustment signal of a variable output level; and a feedback type amplification unit for amplifying the output voltage of the conversion circuit to produce a monitor signal; wherein amplification unit includes gain control circuit for controlling gain of said amplification unit; the shift adjustment signal is supplied to a feedback loop of the amplification unit.