Gate turn-off device driving a power switching semiconductor device

Claim 1

IN COMBINATION, A LOAD CIRCUIT ADAPTED TO BE CONNECTED TO A VOLTAGE SOURCE; A SEMICONDUCTIVE SWITCHING DEVICE INCLUDING AT LEAST A BASE ELECTRODE, A COLLECTOR ELECTRODE AND AN EMITTER ELECTRODE AND HAVING A CONDUCTING STATE AND A NON-CONDUCTING STATE FOR CONTROLLING CURRENT IN SAID LOAD CIRCUIT; MEANS FOR CONNECTING SAID BASE ELECTRODE TO A FIRST SOURCE OF POTENTIAL; A GATE TURN-OFF DEVICE; MEANS FOR CONNECTING A SECOND SOURCE OF POTENTIAL THROUGH SAID GATE TURN-OFF DEVICE TO SAID BASE ELECTRODE; SAID FIRST AND SECOND SOURCES OF POTENTIAL BEING OF SUCH A POLARITY THAT THE SEMICONDUCTIVE SWITCHING DEVICE IS IN ONE STATE WHEN SAID GATE TURN-OFF DEVICE IS OFF AND IS IN THE OTHER STATE WHEN SAID GATE TURN-OFF DEVICE IS TURNED ON; PULSE MEANS FOR ALTERNATELY TURNING ON AND TURNING OFF SAID GATE TURN-OFF DEVICE; MEANS FOR DELAYING THE ALTERNATING OF SAID LAST-MENTIONED MEANS FOR A PREDETERMINED TIME AFTER EITHER TURNING ON SAID GATE TURN-OFF DEVICE FOR TURNING OFF SAID GATE TURN-OFF DEVICE; SAID MEANS FOR DELAYING INCLUDING A FIRST CAPACITOR CONNECTED ACROSS SAID BASE-COLLECTOR CIRCUIT TO BE CHARGED WHEN SAID SEMICONDUCTIVE DEVICE IS IN SAID ONE STATE; A SECOND CAPACITOR CONNECTED ACROSS SAID BASE-EMITTER CIRCUIT TO BE CHARGED WHEN SAID SEMICONDUCTIVE DEVICE IS IN SAID OTHER STATE; AND REFERENCE MEANS FOR ENABLING SAID PULSE MEANS TO TURN-OFF SAID GATE TURN-OFF DEVICE IS RESPONSE TO A PREDETERMINED CHARGE ON ONE OF SAID CAPACITORS AND FOR ENABLING SAID PULSE MEANS TO TURN-OFF SAID GATE TURN-OFF DEVICE IN RESPONSE TO A PREDETERMINED CHARGE ON THE OTHER OF SAID CAPACITORS.