Patent ID: 7394989

Claim:
A signal transmission device comprising: a transmission unit that converts a first portion of an inputted electrical signal capable of including image information into an optical signal, converts a second portion of the electrical inputted signal into an electrical control signal including control information other than the image information, outputs the optical signal and the electrical control signal; a reception unit that inputs the optical signal and the electrical control signal, and outputs an output-use electrical signal including image information from the optical signal and a control signal; and an optical fiber cable that transmits the optical signal and an electrical cable, connecting the transmission unit and the reception unit, that transmits the electrical control signal, wherein the transmission unit includes: an electrical-optical conversion unit that converts the first portion of the inputted electrical signal into the optical signal and outputs the optical signal, a transmission-side electrical signal input and output unit that is disposed independently from the electrical-optical conversion unit and outputs the electrical control signal including control information other than the image information, a transmission-side detection unit that detects the image information from the inputted electrical signal, a receiving unit that receives, from the reception unit, a status signal representing an arrival status of the optical signal, and a control unit that controls the electrical-optical conversion unit based on a detection result of the transmission-side detection unit and the status signal of the receiving unit so that the optical signal is shut down in a case where image information is not included in the inputted electrical signal.