| 摘要 |
PROBLEM TO BE SOLVED: To eliminate temp. fluctuation in bias light by obtaining a control voltage deciding the bias light at a recording time with subtraction of a fixed value without voltage division. SOLUTION: At the reproducing time, though a switch 9 selects the control voltage 101, at a recording time, the switch 9 selects the control voltage 102, and a memory 6 stores analogically the control voltage 101 at this point of time by a ground signal sent from the switch 9 simultaneously at a this selection time. The output voltage of the memory 6 is attenuated by that a fixed voltage value is subtracted with a voltage attenuation circuit 8 to become the control signal 102. The control voltage 102 is inputted to an LD(laser diode) drive current generation circuit 10 to decrease a drive current to an LD to a bias current at the recording time. The voltage attenuation circuit 8 is composed of a voltage source 82 generating a fixed value voltage and a subtracter 81 subtracting the fixed value voltage. |
