Patent ID: 8144256
Filing Date: 2012-03-27
Classification: H04N

Abstract:
1. A video signal transmission unit comprising: a daisy-chained input circuit including an input terminal that can be connected to an output of a first video signal transmission unit through a signal cable for inputting a video signal from the input terminal; a daisy-chained output circuit including an output terminal that can be connected to an input of a second video signal transmission unit through a signal cable for outputting a video signal to the output terminal; and a video input circuit that can be connected to a video signal output device for outputting a video signal and outputs the video signal input from the video signal output device to the daisy-chained output circuit, wherein the daisy-chained input circuit and the daisy-chained output circuit are implemented as a DC coupling circuit, wherein the video input circuit includes a switch section for switching between a connection state and a non-connection state between the video signal output device and the daisy-chained output circuit and a first output transistor connected to output of the switch section, wherein, if the video signal output device and the daisy-chained output circuit are in the non-connection state, the switch section applies 0bias to the first output transistor and the first output transistor is cut off, and if the video signal output device and the daisy-chained output circuit are in the connection state, the first output transistor is turned on by the bias of the output signal of the video signal output device and the signal of the video signal output device is output from the daisy-chained output circuit, and wherein the daisy-chained input circuit includes a second output transistor which is turned off if the video signal is not input from the first video signal transmission unit, and turned on by the bias of the video signal if the video signal is input from the first video signal transmission unit.