Automatic exposure control systems for cameras

Claim 1

SERVO MEANS FOR AUTOMATICALLY ADJUSTING THE SHUTTER OPENING OF A CAMERA IN RESPONSE TO VARIATIONS IN TARGET AREA ILLUMINATION WITH RESPECT TO A PRESELECTED OPTIMUM REFERENCE VALUE OF SAID ILLUMINATION COMPRISING, PHOTOSENSITIVE TRANSDUCER MEANS RESPONSIVE TO SAID ILLUMINATION, REFERENCE MEANS OR BIASING SAID TRANSDUCER MEANS TO SAID OPTIMUM REFERENCE VALUE OF SAID ILLUMINATION, A NULL BALANCE MEANS INCLUDING SAID TRANSDUCER MEANS, SAID TRANSDUCER MEANS ACTING TO UNBALANCE SAID NULL BALANCE MEANS AS A FUNCTION OF VARIATIONS IN TARGET AREA ILLUMINATION, SAID NULL BALANCE MEANS PRODUCING AN OUTPUT SIGNAL AS A FUNCTION OF THE UNBALANCE THEREIN, A TRIGGER GENERATING MEANS, MEANS FOR COUPLING SAID OUTPUT SIGNAL TO SAID TRIGGER GENERATING MEANS, SAID TRIGGER GENERATING MEANS PRODUCING TRIGGER PULSES AS A FUNCTION OF THE CHARACTERISTICS OF SAID OUTPUT SIGNAL, A POWER SOURCE, DRIVE MEANS ENERGIZED FROM SAID POWER SOURCE, A POWER CONTROL GATE MEANS CONNECTED BETWEEN SAID POWER SOURCE AND SAID DRIVE MEANS AND COUPLED WITH SAID TRIGGER MEANS WHEREBY POWER IS SELECTIVELY GATED FROM SAID POWER SOURCE TO SAID DRIVE MEANS BY SAID