Adjustable focus voltage control circuit

Claim 1

IN A COLOR TELEVISION RECEIVER HAVING A COLOR CATHODE RAY TUBE WITH AN ANODE ELECTRODE AND A FOCUS ELECTRODE, A SOURCE OF HIGH VOLTAGE, A HORIZONTAL OUTPUT TRANSFORMER WHEREIN PULSE VOLTAGES ARE DEVELOPED PROVIDING A POTENTIAL WHICH IS APPLIED TO THE ANODE ELECTRODE, AND VOLTAGE REGULATING MEANS RESPONSIVE TO VARIATIONS IN SAID PULSE VOLTAGES, AN ADJUSTABLE FOCUS VOLTAGE CONTROL CIRCUIT COMPRISING IN COMBINATION: A RECTIFIER; MEANS FOR COUPLING PULSE VOLTAGES FROM SAID HORIZONTAL OUTPUT TRANSFORMER TO SAID RECTIFIER; MEANS FOR COUPLING A SELECTED PORTION OF DC POTENTIAL TO SAID RECTIFIER; MEANS COUPLED TO SAID MEANS FOR COUPLING A SELECTED PORTION OF DC POTENTIAL TO SAID RECTIFIER FOR DYNAMICALLY ALTERING THE MAGNITUDE OF SAID SELECTED PORTION OF POTENTIAL IN RESPONSE TO ALTERNATIONS IN THE MAGNITUDE OF SAID PULSE VOLTAGE; AND MEANS FOR APPLYING THE DC POTENTIAL AVAILABLE FROM SAID RECTIFIER TO SAID FOCUS ELECTRODE, SAID DC POTENTIAL INCLUDING THE RECTIFIED PULSE VOLTAGES AND THE DYNAMICALLY ALTERED SELECTED PORTION OF POTENTIAL APPLIED TO SAID RECTIFIER WHEREBY THE POTENTIAL APPLIED TO SAID FOCUS ELECTRODE VARIES IN PROPORTION TO THE PONTENTIAL APPLIED TO SAID ANODE ELECTRODE OF SAID CATHODE RAY TUBE.