Automatic focusing circuit

摘要: An automatic focusing circuit in a video camera separates high frequency component from the signal obtained an image sensing 4 for every field. After separated is integrated integration 10, result converted into digital value by A/D converter 11 and applied to holding 12 as focus evaluating value. The 12, which comprises first fifth memories coupled series, always holds newest successive five values. largest detected maximum detecting 18 field memory 19. compared with one before held 20 comparator 21. If 19 decreased, motor control 22 inverts rotational direction of 3. Thus, since ring slightly vibrated maximal point value, lens can be in-focus position.