| 摘要 |
PURPOSE:To enable optical signals to fall at a high speed without making a semiconductor light emitting element delay in light emission time by a method wherein a negative pulse is added to the drive current of the semiconductor light emitting element at the fall of input data. CONSTITUTION:When binary input data are applied to a fall pulse generating circuit 2, binary signals outputted from the circuit 2 are inputted into a level shift circuit 3. The level shift circuit 3 outputs signals shifted in level so as to enable a waveform compounding circuit 4 to form negative pulses. The signals shifted in level and the input data are inputted into the waveform compounding circuit 4, the circuit 4 outputs ternary waveforms including negative pulses, and a drive circuit 5 is made to drive a semiconductor light emitting element 1 with the ternary waveforms concerned. At this point, as negative pulses are added to the semiconductor light emitting element 1 at the fall of input data, a reverse current flows through the element 1 at quenching, and charges stored in the semiconductor light emitting element 1 are discharged. As a result, optical signals fall quickly. |
