CAMERA DE TELEVISION AVEC FOCALISATION AUTOMATIQUE DU FAISCEAU D'ANALYSE SUR LA CIBLE PHOTOSENSIBLE

摘要

The image signal from the photosensitive target (10) of an image tube (14) is applied to a preamplifier (22) to provide a video signal (SV). The video signal is applied to a contour extraction circuit (24) where rapid transitions of the video signal are obtained for fine resolution marks on the target. These marks are provided for the focussing system. A peak detector (26) provides a signal (SN) representing the max. level of the extraction circuit output. The detector output is rectified and filtered and applied to an A/D converter (34) for input into a microprocessor (32). This controls a window circuit (28) for the detector and also provides a correction signal for focussing of the image tube signal. The correction signal is obtained from a look up table and is applied to the tube focussing circuits (20) through a D/A converter (36).