Current control apparatus having phase controlled means for variably controlling the period of conduction

Claim 1

IN COMBINATION, A FIRST SILICON CONTROLLED RECTIFIER HAVING AN ANODE, A CATHODE, AND A GATE ELECTRODE; MEANS FOR CONNECTING THE ANODE AND CATHODE OF SAID RECTIFIER TO A LOAD AND TO A SOURCE OF ALTERNATING POWER TO CONTROL THE CURRENT FLOW THROUGH THE LOAD; AN IMPEDANCE SO CONNECTED BETWEEN THE GATE ELECTRODE AND CATHODE THAT WHEN A VOLTAGE DROP OF A PREDETERMINED POLARITY APPEARS ACROSS SAID IMPEDANCE SAID FIRST RECTIFIER IS RENDERED CONDUCTIVE; A FURTHER SILICON CONTROLLED RECTIFIER CONNECTED TO A SOURCE OF POWER IN SERIES WITH SAID IMPEDANCE AND IN PARALLEL WITH THE ANODE AND CATHODE OF SAID FIRST RECTIFIER, SAID FURTHER SILICON CONTROLLED RECTIFIER HAVING A GATE ELECTRODE; ADJUSTABLE CONTROL MEANS FOR APPLYING TO SAID GATE ELECTRODE OF SAID FURTHER RECTIFIER A VOLTAGE WHOSE PHASE POSITION IS ADJUSTABLY VARIABLE AND WHICH IS OF A MAGNITUDE AND POLARITY TO INITIATE CONDUCTION OF SAID FURTHER RECTIFIER TO CAUSE CURRENT FLOW THROUGH SAID IMPEDANCE, SAID FURTHER RECTIFIER BEING CONNECTED TO SAID IMPEDANCE IN SUCH A DIRECTION THAT THE RESULTING VOLTAGE DROP ACROSS SAID IMPEDANCE DUE TO SAID FURTHER RECTIFIER BEING CONDUCTIVE CAUSES A VOLTAGE DROP OF SAID PREDETERMINED POLARITY ACROSS SAID IMPEDANCE TO CAUSE SAID FIRST RECTIFIER TO BECOME CONDUCTIVE, SAID PARALLEL CONNECTION OF SAID FURTHER RECTIFIER WITH THE ANODE AND CATHODE OF SAID FIRST RECTIFIER BEING EFFECTIVE UPON SAID FIRST RECTIFIER BECOMING CONDUCTIVE TO RESULT IN THE REMOVAL OF THE VOLTAGE ACROSS SAID FURTHER RECTIFIER TO CAUSE IT TO CEASE CONDUCTION; AND MEANS FOR ENERGIZING SAID ADJUSTABLE CONTROL MEANS FROM A SOURCE OF POWER INDEPENDENT OF THE VOLTAGE DROP ACROSS SAID FIRST RECTIFIER.