Exposure Control Circuit for an Electrically Shuttered Image Tube.
OFFICE OF THE SECRETARY OF THE ARMY WASHINGTON D C
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The patent is an automatic control system for the shutter of an electronically shuttered image tube exposed to varying light conditions. The system includes a relay between the shutter and the power supply for the shutter. The relay contacts are closed by a pulsed signal and opened in response to photocathode current in the tube. When sufficient current has flowed in the photocathode to give an acceptable image, the relay is opened. The current is measured in a circuit including an a-c amplifier fed by the commutated output of the photocathode. The amplifier output is full-wave rectified and integrated. The integrated signal operates a Schmitt trigger, and the trigger turns-off the photocathode relay.
- Electrooptical and Optoelectronic Devices