Television camera regulating system

Claim 1

IN A TELEVISION CAMERA INCLUDING A PICTURE PICK-UP TUBE OPERATING ON THE VIDICON PRINCIPLE AND DEVELOPING A VIDEO SIGNAL CURRENT AT THE SIGNAL PLATE THEREOF AND IN WHICH THE AMPLITUDE OF THE SIGNAL CURRENT, FOR A PREDETERMINED BRIGHTNESS OF AN OPTICAL IMAGE THEREON, IS DEPENDENT UPON THE VALUE OF A DIRECT-CURRENT BIASING VOLTAGE APPLIED TO THE SIGNAL PLATE, MEANS FOR RECTIFYING VIDEO SIGNAL CURRENT DERIVED FROM SAID SIGNAL PLATE AND PRODUCING RECTIFIED SIGNAL CURRENT, VOLTAGE REGULATING MEANS CONTROLLED BY SAID RECTIFIED SIGNAL CURRENT AND VARYING THE VALUE OF SAID BIASING VOLTAGE APPLIED TO THE SIGNAL PLATE TO MAINTAIN THE MEAN SIGNAL CURRENT SUBSTANTIALLY CONSTANT, AN ADJUSTABLE DIAPHRAGM SHUTTER IN THE OPTICAL SYSTEM OF THE PICK-UP TUBE, AND MEANS CONTROLLED BY SAID RECTIFIED SIGNAL CURRENT FOR SIMULTANEOUSLY ADJUSTING SAID SHUTTER TO MOVE THE SHUTTER IN THE OPENING DIRECTION AS THE PICTURE SIGNAL DECREASES AND TO MOVE THE SHUTTER IN THE CLOSING DIRECTION AS THE PICTURE SIGNAL INCREASES.