Firing circuit for controlled switching devices in power supply circuits having a periodic output

Claim 1

A POWER SUPPLY CIRCUIT ADAPTED TO BE CONNECTED TO AN INPUT AC SOURCE FOR CONVERTING THE INPUT AC THEREFROM INTO A PERIODIC OUTPUT CURRENT HAVING AN ADJUSTABLE POWER LEVEL ADAPTED TO BE APPLIED TO A LOAD, SAID POWER SUPPLY CIRCUIT COMPRISING IN COMBINATION: CURRENT SWITCHING MEANS CONNECTED BETWEEN THE AC SOURCE AND THE LOAD, AND HAVING A DUTY CYCLE COMPRISING A LOW IMPEDANCE STATE OPERABLE TO PASS CURRENT THERETHROUGH TO THE LOAD AND A HIGH IMPEDANCE STATE OPERABLE TO OPPOSE CURRENT FLOW THERETHROUGH, THE DUTY CYCLE BEING VARIABLE TO CONTROL THE POWER LEVEL OF THE PERIODIC OUTPUT CURRENT; IMPEDANCE MEANS RESPONSIVE TO THE PERIODIC OUTPUT CURRENT FOR DEVELOPING A PERIODIC VOLTAGE HAVING AT LEAST IN PART A RAMP-LIKE WAVESHAPE; MEANS FOR PROVIDING A REFERENCE POTENTIAL; COMPARING SWITCHING MEANS FOR COMPARING THE RAMPLIKE PORTION OF THE PERIODIC VOLTAGE TO SAID REFERENCE POTENTIAL, SAID COMPARING MEANS HAVING TWO SWITCHING STATES RESPONSIVE TO SAID COMPARISON WHICH ARE PERIODICALLY AND ALTERNATELY ESTABLISHED THEREIN DUE TO THE PERIODIC OUTPUT CURRENT; TRIGGER PULSE GENERATING MEANS RESPONSIVE TO THE SWITCHING STATE OF SAID COMPARING MEANS FOR PROVIDING A PERIODIC SEQUENCE OF TRIGGER PULSES TO SAID CURRENT SWITCHING MEANS WHICH IN CONJUNCTION WITH THE INPUT AC PERIODICALLY AND ALTERNATELY ESTABLISH THE LOW AND THE HIGH IMPEDANCE STATES IN SAID CURRENT SWITCHING MEANS, THE SEQUENCE OF TRIGGER PULSES BEING SYNCHRONIZED WITH THE INPUT AC AND PHASE DISPLACED THEREFROM; MEANS FOR VARYING THE PHASE DISPLACEMENT BETWEEN THE SEQUENCE OF TRIGGER PULSES AND THE INPUT AC FOR CONTROLLING DUTY CYCLE OF SAID CURRENT SWITCHING MEANS TO ADJUST THE POWER LEVEL OF THE PERIODIC OUTPUT CURRENT; AND MEANS FOR PROVIDING STARTING PULSES WHICH INITIATE THE SWITCHING OF THE IMPEDANCE STATES OF SAID CURRENT SWITCHING MEANS.