| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a signal transmission system capable of transmitting a signal at high speed even when a signal line for network control and a power supply line are wired through the same cable. SOLUTION: A power unit/communication power conveying circuit 11 alternately switches signal transmission and power supply in time-division manner. An I/O device 13 changes over a switcher 21 to the side of a communication circuit 23 at the time of signal transmission and changes over the switcher to the side of a power source part 24 at the time of power supply by operating a control circuit 22 synchronously with the switching operation of the power unit/communication power conveying circuit 11. At the time of signal transmission, a variable impedance element 25 of the communication circuit 23 is set to an optimal value corresponding to the impedance of a cable 12. When the power unit/communication power conveying circuit 11 is switched to power supply, the I/O device 13 stores power to be supplied to the power source part 24 in a capacitor 26 and supplies the power to respective circuits and afterwards, when the circuit 11 is switched to signal transmission, operating power is supplied to the respective circuits by the power stored in the capacitor 26.</p> |
