CIRCUIT FOR AUTOMATICALLY CONTROLLING THE BRIGHTNESS OF A MONITOR TO MAINTAIN THE STABLE BRIGHTNESS OF THE MONITOR ALWAYS

摘要

PURPOSE: A circuit for automatically controlling the brightness of a monitor is provided to maintain the stable brightness of the monitor always by controlling a contrast level of a monitor video amplifier using the change of current which flows in an FBT(Fly Back Transformer). CONSTITUTION: A video amplifying unit(20) outputs an inputted video signal to a Braun tube(10) according to a set amplification degree. A contrast control voltage supply unit(30) supplies a contrast control voltage to the video amplifying unit, and sets the amplification degree. A brightness adjusting unit(40) controls the control voltage supplied to the contrast control voltage supply unit in response to the change of current which flows in an FBT, and controls the amplification degree of the video amplifying unit.