Automatic range finder for camera

Claim 1

A range finder, comprising; a plurality of light sources for applying a plurality of infrared beams to an object for distance measurement; an infrared source drive circuit for causing said plurality of light sources to sequentially emit infrared beams; a light projecting lens provided on optical axes of said light sources; a condenser lens positioned a predetermined base length apart from said optical axes of said light sources, an optical axis of said condenser lens being parallel to an optical axis of said light projecting lens; said light projecting lens and said condenser lens being fixed in position relative to said light sources, a light detecting element having a light receiving surface arranged perpendicular to said optical axis of said condenser lens, said light detecting element producing first and second signals indicative of a position of a light spot on said light receiving surface; said light sources being positioned apart from one another by a predetermined uniform distance; and processing circuit means for determining, for values of said first and second signals produced by said light detecting element for each of said light sources, which of said values corresponds to an object closest to said range finder and for setting a focus position of said camera in accordance with said determination, said processing circuit means including means for correcting a value obtained from said first and second signals in accordance with a distance correction signal having a magnitude determined in accordance with said uniform distance.