| 摘要 |
PURPOSE:To attain correct pit formation and recording by high speed switching by using bias power, for which driving at the time of recording is set weaker than the reproducing power, as a base and superimposing prescribed power to this bias power as recording power. CONSTITUTION:At the time of recording, a recording current value I3 determined by a current setting circuit 16 flows through a third constant current source 15 to a semiconductor laser 2 so that a switch element 8 can be turned off and prescribed recording power can be outputted, and a switch element 14 is turned on/off corresponding to a recording information signal. In such a way, the bias power, for which driving at the time of recording is set weaker than the reproducing power, is used as the base and the prescribed power is superimposed to this bias power and defined as the recording power. Thus, the correct pit formation is attained in the case of recording and recording is enabled by high-speed switching as well. |
