Photoelectric rangefinder

摘要

A photoelectric rangefinder for use in a photographic camera for automatically focusing an image of a target object on a predetermined image plane. The system utilizes an electro-optical spatial filter having at least two photoresponsive elements to find the difference in phase between output signals from the respective photoresponsive elements. A signal indicative of the difference in phase between the output signals from the photoresponsive elements is used to move a phototaking objective lens along its optical path to reposition the objective lens in search for a true focus setting. The objective lens is brought into proper focus when the signal indicative of the phase difference assumes a predetermined electric relation with an electric signal indicative of the position of the objective lens along its optical axis.