Circuit for maintaining a load energized at decreased power following energization

Claim 1

IN AN ELECTRICAL CONTROL SYSTEM FOR ENERGIZING A LOAD OF THE TYPE REQUIRING LESS CURRENT TO MAINTAIN ENERGIZATION OF THE LOAD THAN IS REQUIRED FOR INITIAL ENERGIZATION THEREOF, AN ELECTRICAL POWER SUPPLY SOURCE, A CONTROLLABLE SEMI-CONDUCTOR DEVICE CONNECTIBLE TO SAID SOURCE FOR CONTROLLING ENERGIZATION OF THE LOAD, SAID SEMI-CONDUCTOR DEVICE HAVING MAIN ELECTRODES AND A CONTROL ELECTRODE, CURRENT LIMITING MEANS COMPRISING A RESISTOR FOR LIMITING THE CURRENT TO THE LOAD WHEN SAID SEMI-CONDUCTOR DEVICE IS RENDERED NON-CONDUCTING, SAID CURRENT LIMITING MEANS CONNECTED IN PARALLEL WITH SAID MAIN ELECTRODES, AND CONTROL MEANS COMPRISING A CAPACITOR AND A RESISTOR CONNECTED IN A SERIES CIRCUIT ACROSS SAID SOURCE, THE JUNCTION OF SAID CAPACITOR AND RESISTOR CONNECTED TO SAID CONTROL ELECTRODE TO AFFORD A BIAS VOLTAGE TO RENDER SAID SEMI-CONDUCTOR DEVICE CONDUCTIVE WHEN THE LATTER IS CONNECTED TO SAID SOURCE, SAID CAPACITOR CHARGING RESPONSIVE TO CURRENT FLOW IN SAID SERIES CIRCUIT CAUSING SAID BIAS VOLTAGE TO DECREASE TO RENDER SAID SEMI-CONDUCTOR DEVICE NON-CONDUCTING, THEREBY RENDERING SAID CURRENT LIMITING MEANS EFFECTIVE TO DECREASE THE CURRENT IN THE LOAD CIRCUIT.