Electrical proportional control system

Claim 1

IN A CONTROL SYSTEM INCLUDING MEANS RESPONSIVE TO ELECTRICAL ENERGY FOR CONTROLLING A PHYSICAL CONDITION, APPARATUS FOR ESTABLISHING AND MAINTAINING A PREDETERMINED STATE OF THE CONDITION BY REGULATING THE SUPPLY OF EECTRICAL ENERGY TO THE CONTROLLING MEANS, THE REGULATING APPARATUS COMPRISING: FIRST MEANS FOR PRODUCING AN ELECTRICAL CONDITION SIGNAL HAVING A MAGNITUDE REPRESENTING THE INSTANTANEOUS STATE OF THE CONDITION; SECOND MEANS FOR PRODUCING A REFERENCE SIGNAL; MEANS COUPLED TO THE FIRST AND SECOND MEANS FOR DEVELOPING AN ELECTRICAL ERROR SIGNAL HAVING A POLARITY REPRESENTING THE DIRECTION AND A MAGNITUDE REPRESENTING THE EXTENT OF DEVIATION OF THE CONDITION SIGNAL FROM THE REFERENCE SIGNAL; MEANS COUPLED TO THE CONTROLLING MEANS AND INCLUDING A SEMICONDUCTOR SWITCH HAVING A CONTROL ELEMENT, FOR SUPPLYING PERIODIC ELECTRICAL ENERGY TO THE CONTROLLING MEANS; AND MEANS COUPLED TO THE SWITCH CONTROL ELEMENT AND INCLUDING A MAGNETIC AMPLIFIER COUPLED TO THE DEVELOPING MEANS FOR GENERATING A SQUARE-WAVE, SWITCHCLOSING CONTROL SIGNAL HAVING A LEADING EDGE OCCURRING AT TIMES DURING THE PERIODS OF PERIODIC ELECTRICAL ENERGY DETERMINED BY THE ERROR SIGNAL.