| 摘要 |
PURPOSE:To attain a driving circuit of a semiconductor laser having a flexibility by forming a reference voltage for setting the optical output of the semiconductor laser from a recording signal to make the high level and the low level of the optical output of the semiconductor constantly fixed without depending on the production probability of '1' and '0' of the recording signal. CONSTITUTION:An APC loop controls a bias current so as to make an optical output control signal 50 equal to an optical monitor signal 13 and consequently, the optical output of the semiconductor laser 1 is maintained to a constant value. If the response characteristic after the recording signal is inputted until the semiconductor laser emits light and the optical output monitor signal 13 is obtained is not equal to the responsiveness for obtaining a reference signal 12 is obtained from a reference voltage generating circuit 1, the APC is not normally operated. Then, the values of a resistance 44R3 and a capacitor 45C are suitably set and the characteristic of a low-pass filter is changed to set the above-mentioned responsiveness. |
