| 摘要 |
PROBLEM TO BE SOLVED: To obtain a video image distribution amplifier where an input is in bridge connection, a termination resistor is automatically inserted and no special connector or the like is in use and a video image distribution amplifier system employing the amplifier. SOLUTION: A video signal source 5 gives a video signal to a video distribution amplifier 1-1 through a coaxial line via an input receptacle IN and the video signal is given to an input receptacle IN of a video distribution amplifier 1-2 via a coaxial line (g) from a receptacle IN' as a bridge input, a switch S is closed in the video distribution amplifier 1-2 and a termination resistor R terminates the coaxial line. An coaxial outer sheath of the bridge output coaxial receptacle IN' is not connected to the ground in the inside of the video distribution amplifiers 1-1, 1-2, but its level is boosted to a voltage Vcc via a boosting resistor (r). When the video distribution amplifiers 1-1, 1-2 are in bridge connection by the coaxial line (g), the coaxial cable outer sheath is connected to the ground and an input voltage of a control circuit 3 is 0V, then the control circuit 3 detects the bridge connection and disconnects the termination resistor R. |
