| 摘要 |
PURPOSE:To prevent delay in transmission start by setting a level of a bias signal to a prescribed region in a natural lighting region of a semiconductor light emitting element when no burst signal is inputted to reduce the leading time of the bias signal. CONSTITUTION:A signal is outputted from a burst control signal output circuit 2 at the end of transmission of transmission data, a switch circuit 7 is conducted to discharge an electric charge in a capacitor 5. As a result, a bias voltage is decreased and a semiconductor laser circuit 6 is restored to the initial state, and when the charging voltage of the capacitor 5 is lowered up to the limit level, a TR21 of a limit circuit 20 is conducted and the bias voltage is fixed to an output voltage of a power supply 22. When a burst signal RS comes again in this state and the switch circuit 3 is conducted, since charging to the capacitor 5 is started from the limit level, the bias voltage reaches a prescribed burst lighting level in a short time. |
