Circuit for automatically focusing a camera based on changes in luminance signals derived from optical signals received by the camera

摘要

An automatic focus circuit for use with a video camera comprises an analog to digital converter which converts an analog luminance signal provided from an image signal processing circuit into a digital luminance signal, a microcomputer for controlling the automatic focus unit using an integrated luminance value which is integrated in an integrating circuit, and an area dividing circuit for horizontally and vertically dividing a screen of a video camera monitor. The automatic focus operation is easily performed by using the integrated digital luminance value as stored in a memory circuit. Accordingly, the automatic focus circuit simplifies the constitution and accuracy of the automatic focus.