Automatic black level stabilizing apparatus

摘要

An apparatus for automatically stabilizing the black level of a displayed picture when (1) an automatic black level stabilizing function is OFF, (2) black level error occurs between at an ON state and at an OFF state and (3) black level variation and picture disturbance occurs during activation and deactivation of the automatic black level stabilizer. Black level variations when the automatic black level stabilizer are OFF is controlled by processing a cathode current in a negative feedback loop and controlling a CRT grid voltage, storing a divided grid voltage during a converging period and processing the grid voltage in another negative feedback loop in order to adjust the grid voltage to an ON state value.