AUTOMATIC BRIGHTNESS CONTROL CIRCUIT OF VIDEO DISPLAY

摘要

PURPOSE: An automatic brightness control circuit of a video display is provided to control easily brightness of a screen by controlling a control grid voltage. CONSTITUTION: The automatic brightness control circuit of a video display comprises a fly-back transformer(FBT), a control portion(10), and a control grid voltage control portion(20). The fly-back transformer(FBT) generates a screen grid voltage of positive potential to provide directly it to a screen grid of a cathode ray tube(CRT) and generates a screen grid voltage of a negative potential. The control portion(10) outputs a control voltage for controlling the control grid voltage. The control grid voltage control portion(20) varies the control grid voltage of the negative potential and provides it to a control grid(G1) of the cathode ray tube.