Frame based vertical panning system

摘要

A television apparatus comprises a display for a video signal and a panning control circuit. The panning control circuit counts the horizontal lines, or half lines, and generates a vertical reset signal delayed by a variable pan delay relative to the vertical synchronizing component of the video signal. The pan delay varies in a first range for vertically panning the video signal down and varies in a second range for vertically panning the video signal up. The first and second ranges are mutually exclusive to control interline flicker of the panned video signal when successive fields have different numbers of horizontal lines. The first range is less than the number of horizontal lines in each field and the second range is greater than the number of horizontal lines in each field and less than the number of horizontal lines in each frame.