AUTOMATIC CONTROL CIRCUIT FOR IMAGE INTENSIFIER

摘要

An automatic brightness control circuit for an image intensifier tube includes direct current limiting means for limiting the output of an oscillator which provides alternating current to a voltage divider supplying high voltages to the cascaded stages of the tube. Means for monitoring the direct current is provided in series with the oscillator or with the tube output electrodes, changes are amplified, compared to a reference and a difference signal applied to the current limiter to control the direct current in the oscillator. Additional means may be provided for monitoring the direct voltage at the oscillator or output stage and for combining the monitored current and voltage signals. Flash response circuitry may also be added to monitor the current in the input electrode or first stage of the tube and temporarily disconnect the high voltage to the output electrode or cut-off the first stage of the tube upon the occurrence of a predetermined current surge.