JPS647774A - Autofocus video camera - Google Patents

Abstract

PURPOSE:To always achieve stable autofocussing action rapidly without malfunction by providing a zooming mechanism, a focus evaluation value detecting means, a focus lens moving means, and respective response characteristic switching means. CONSTITUTION:From an image formed by a lens 1, an illluminating signal is generated by an image pickup circuit 4 and inputted to a focus evaluation ganerating circuit 5. After starting autofocussing action, first focus evaluation value is held in a maximum value memory 10 and an initial value memory 11. Thereafter, a first focus motor control circuit 15 rotates a focus motor 3, monitors a second comparator 13, and compares a focus evaluation value with the evaluation value held in the memory 11 to output the result. After executing such quick autofocussing action as above, the lens is stopped, and the lens is finely adjusted positionally by a second focus motor control circuit 17 even if the lens stops at a position out of focus because of a violent moving of an object. In such a way, the zooming area of the zoom lens can be detected, as well as a focus position can be detected rapidly.