Accession Number : ADD009028

Title :   Automatic Exposure Control for Pulsed Active TV Systems.

Descriptive Note : Patent,


Personal Author(s) : Thomas,Larry A

Report Date : 22 Sep 1981

Pagination or Media Count : 6

Abstract : An automatic exposure control system is disclosed for TV cameras, particularly those of the active type wherein a pulsed light source provides scene illumination for the camera. The control system includes a major control loop wherein an instantaneous photocathode current signal is time-separated from the total sensor signal of an image tube and integrated to provide a real-time measure of the total instantaneous light input upon the photocathode of the tube. When the total light input reaches a predetermined exposure level, a pulse is generated for gating off the image tube via a high voltage supply therefor so that a constant effective exposure is provided the photocathode. Peak levels of the photoelectron current are used to vary the amount of light entering the system and a conventional video detector is included to regulate the photocathode voltage thereby permitting a relatively constant video output signal to be maintained throughout a wide range of input light conditions. (Author)

Descriptors :   *Patents, *Television cameras, *Gates(Circuits), *Control systems, Range(Extremes), Exposure(General), Light pulses, Video signals, Television systems, Image tubes, Photoelectrons, High voltage, Currents, Control, Pulses, Photocathodes, Supplies, Signals, Illumination, Output, Loops, Constants, Input, Detectors, Automation, Light

Subject Categories : Non-radio Communications

Distribution Statement : APPROVED FOR PUBLIC RELEASE