Pincushion correction circuit having saturable reactor with asymmetrical parabolic waveform applied to the control winding

Claim 1

IN COMBINATION, MEANS FOR PRESENTING A VARIABLE IMPEDANCE COMPRISING A SATURABLE REACTOR INCLUDING A CONTROL WINDING AND AT LEAST ONE OTHER WINDING, THE IMPEDANCE OF SAID OTHER WINDING BEING SUBJECT TO VARIATIONS IN RESPONSE TO CHANGES IN CURRENT THROUGH SAID CONTROL WINDING; A UTILIZATION CIRCUIT INCLUDIJNG A SOURCE OF CURRENT AND SAID OTHER WINDING; AND MEANS FOR CAUSING THE CURRENT THROUGH SAID OTHER WINDING A VARY IN ACCORDANCE WITH A DESIRED PERIODIC FUNCTION, THE PERIODIC CURRENT VARIATION BEING SUBSTANTIALLY SYMMETRICAL IN THAT RECURRING CURRENT MINIMUMS ARE SPACED IN TIME FROM IMMEDIATELY PERCEDING AND SECCEEDING CURRENT MAXIMUMS BY SUBSTANTIALLY EQUAL TIME INTERVALS; SAID CURRENT VARIATIONS CAUSING MEANS COMPRISING A SOURCE OF RECURRING VOLTAGE WAVEFORMS HAVING A PERIODICITY CORRESPONDING TO THAT OF SAID DESIRED PERIODIC FUNCTION, AND MEANS INCLUDING A COUPLING FROM SAID CONTROL WINDING TO SAID SOURCE FOR VARYING CURRENT IN SAID CONTROL WINDING IN ACCORDANCE WITH AN ASYMMETRICAL VERSION OF SAID DESIRED PERIODIC FUNCTION, RECURRING CONTROL WINDING CURRENT MINIMUMS BEING SPACED IN TIME FROM IMMEDIATELY PRECEDING AND SUCCEEDING CURRENT MAXIMUMS BY SIGNIFICANTLY UNEQUAL TIME INTERVALS.