System zum vertikalen Panoramieren von Halbbild zu Halbbild

摘要

A television apparatus comprises a display for a video signal representing a picture. The video signal has a vertical synchronizing component defining fields of horizontal lines which can have other than a standard number of horizontal lines per field under certain operating conditions. A counters (1404, 1410) and latches (1408, 1409) measure the number of horizontal lines successive fields. A panning circuit (1416, 1420, 1424, 1430) generates a vertical reset signal (VRST) which is phase shifted by a selected number of horizontal lines (RESET PHASE) relative to the vertical synchronizing component of the video signal for vertically panning the picture on the video display by the selected number of horizontal lines. The selected number of horizontal lines is adjusted responsive to the measured lengths of the fields to maintain the selected amount of vertical panning even under the certain operating conditions.