| 摘要 |
PURPOSE:To obtain a wide communication margin by implementing automatically the control that a transmission level is increased when a duty measured by a receiver side is less than a reference value and the transmission level is lowered when the duty is in excess of the reference value. CONSTITUTION:An optical output control section 11 changes a level of an optical signal outputted from a light emitting diode 12 in response to the attribute of a given control signal to a high level or a low level by a prescribed width each. Then the reception section 20 includes a duty detection section 24 which compares the duty of a waveform of an electric signal shaped by a waveform shaping section 22 with a reference value and generates a control signal with an attribute corresponding to the relation of quantity being the result of comparison and given to an optical output control section 11 of a transmission section 10. In this case, the transmission section 10 outputs a rectangular wave whose duty is 50%. When the duty is less than 50% at the receiver side, the control signal to increase the optical output is sent to the sender side and when less than 50%, the optical output is decreased. |
