Automatic focussing device for photographic cameras

Claim 1

AN AUTOMATIC FOCUSSING MACHANISM FOR PHOTOGRAPHIC CAMERA COMPRISING, A LENS FOR DIRECTING THE LIGHT INCIDENT THEREON TO FOCUS AT THE FOCAL PLANE THEREOF, UNEXPOSED PHOTOGRAPHIC FILM BEING POSITIONABLE AT SAID FOCAL PLANE, A PHOTOCONDUCTIVE ELEMENT HAVING THE CHARACTERISTIC OF R=K/I$, WHERE R DESIGNATES ITS ELECTRICAL RESISTIVITY, I THE LUMINOUS INTENSITY OF THE LIGHT INCIDENT THEREUPON, AND E AND K ARE CONSTANTS SPECIFIC TO IT, A LENS TUBE MOUNTING THE LENS AND MOVABLE ALONG THE OPTICAL AXIS OF THE LENS, AN AUXILIARY LENS FOR DIRECTING LIGHT INCIDENT THEREUPON ALONG AN AXIS PARALLEL TO THAT OF THE LENS TO THE PHOTOCONDUCTIVE ELEMENT, SPRING-BIASED MEANS SUPPORTING THE PHOTOCONDUCTIVE ELEMENT FOR MOTION IN EITHER DIRECTION ALONG SUCH PARALLEL AXIS, CAM MEANS ON THE LENS TUBE FOR MOVING THE PHOTOCONDUCTIVE ELEMENT SUPPORTING MEANS IN SYNCHRONISM WITH, AND IN THE SAME DIRECTION AS, THE LENS TUBE MOVEMENT, ELECTRICAL CIRCUIT MEANS FOR MOVING THE LENS TUBE INCLUDING THE PHOTOCONDUCTIVE ELEMENT, A NORMALLY OPEN SWITCH, A CONTROLLER, AND A MOTOR, GEARING INTERCONNECTING THE LENS TUBE AND THE MOTOR, A SINGLE SPRING-BIASED SHUTTER RELEASE MEANS FOR DEPRESSING TO EXPOSE THE FILM, AND