Focus detecting device

摘要

A focus detecting device for a camera utilizing a self-scanning type photoelectric element array composed of a plurality of minute photoelectric elements. The input signal from the photoelectric element array is held by first and second memory circuits at opposite phases from one another with the holding time for the memory circuit corresponding to twice the scanning time for a single minute photoelectric element within the array. Signals representing the difference and sum of the output of the memory circuits are formed and the absolute value of the difference signal is taken. The sum signal is connected as the divisor signal to a divider circuit while the absolute value of the difference is utilized as the dividend. The peak value of the signal thus formed is utilized as a contrast detection signal. This signal is substantially unaffected by vibration of the camera or movement of the object being photographed.