Patent ID: 8169407

Claim:
A KVM switch comprising: server units that are respectively connected to computers units; user units that are respectively connected to input-output units inputting and outputting a signal to the computer units; and a main unit that connects the server units and the user units selectively, wherein: an input-output unit switches between the computer units where the signal is input and output; a picture signal from a computer unit is fed into the input-output unit via a server unit, the main unit and a user unit in accordance with the following order: the server unit has a first reference signal generator that generates a first reference signal used for a distortion control of the picture signal and a first switch device to select the picture signal from the computer unit or the first reference signal from the first reference signal generator for outputting to the main unit; the main unit has a first controller that receives the first reference signal and the picture signal in common, and outputs the first reference signal or the picture signal with a controlled output voltage level, a first microcomputer which receives the first reference signal output from the first controller, and controls the output voltage level of the first controller based on the received first reference signal, a second reference signal generator generating a second reference signal used for the distortion control of the picture signal and a second switch device to select the picture signal from the server unit or the second reference signal from the second reference signal generator for outputting to the user unit; and the user unit has a second controller that receives the second reference signal and the picture signal in common, a second microcomputer which receives the second reference signal output from the second controller, and controls the output voltage level of the second controller based on the received second reference signal.