Fluorescent lamp dimming circuit

Claim 1

A FLUORESCENT LAMP DIMMING APPARATUS COMPRISING A PAIR OF ALTERNATING CURRENT POWER INPUT TERMINALS, OUTPUT TERMINALS FOR SUPPLYING A LAMP CIRCUTI, A HIGH REACANCE BALAST TRANSFORMER HAVING A PRIMARY WINDING COUPLED ACROSS SAID POWER INPUT TERMINALS, SAID HIGH REACTANT BALLAST TRANSFORMER HAVING A HIGH LEAKAGE REACTANCE SECONDARY COUPLED TO SAID OUTPUT TERMINALS AND OPERATING ON NON-LINEAR PORTION OF ITS EXCITATION MAGNETIZATION CHARACTERISTIC NEAR RATED CURRENT FOR SAID SECONDARY, A CAPACITANCE SERIALLY INTERPOSED BETWEEN SAID SECONDARY AND SAID OUTPUT TERMINALS TO CAUSE THE HIGH REACTANCE SECONDARY TO OPERATE ON A NON-LINEAR PORTION OF ITS CHARACTERISTIC, A FLUORESCENT LAMP CIRCUIT COUPLED ACROSS SAID OUTPUT TERMINALS, A SILICON-CONTROLLED RECTIFIER HAVIN FIRST AND SECOND POWER TRANSMITTING TERMINALS COUPLED SUBSTANTIALLY ACROSS SAID OUTPUT TERMINALS AND HAVING A CONTROL TERMINAL, MEANS COUPLED TO SAID CONTROL TERMINAL FOR OPERATING SAID SILICON-CONTROLLED RECTIFIER TO ADJUSTABLY DIVERT CURRENT OTHERWISE FLOWING THROUGH SAID FLUORESCENT LAMP CIRCUIT DURING A CONTROLLED PORTION OF SUCCESSIVE HALF CYCLES OF THE A.C. INPUT POWER WAVEFORM AS RECEIVED AT SAID INPUT POWER RECEVIING TERMINALS, AND A SATURATING REACTOR COUPLED SUBSTANTIALLY ACROSS SAID INPUT TERMINALS, THE FLUX DENSITY OF SAID REACTOR BEING LESS THAN THE FLUX DENSITY AT THE KNEE OF THE MAGNETIZATION CURVE OF THE CORE THEREOF WHEN SAID FLUORESCENT LAMP IN DRAWING CURRENT, AND DRAWING AN AVERAGE CURRENT EQUAL TO THE CURRENT DRAWN BY THE SILICON-CONTROLLED RECTIFIER DURING THE NEXT SUCCEEDING HALF CYCLE AFTER THE SILICON-CONTROLLED RECTIFIER DRAWS SAID AVERAGE CURRENT.