Lighting control apparatus

Claim 1

APPARATUS FOR VARIABLY CONTROLLING THE CURRENT FROM AN AC SOURCE SUPPLIED TO AN INCANDESCENT LAMP LOAD COMPRISING A PAIR OF TERMINALS FOR CONNECTING SAID APPARATUS TO SAID SOURCE, A PAIR OF GATE CONTROLLED RECTIFIERS, EACH OF SAID GATE CONTROLLED RECTIFIERS RESPECTIVELY COMPRISING ANODE, CATHODE, AND GATE ELECTRODES, CONNECTED IN THEIR ANODE TO CATHODE PATHS IN INVERSE PARALLEL RELATIONSHIP ACROSS SAID TERMINALS, A UNIJUNCTION TRANSISTOR RELAXATION OSCILLATOR COMPRISING A TRANSISTOR HAVING EMITTER AND FIRST AND SECOND BASE ELECTRODES, SAID EMITTER BEING ADAPTED TO BE CONNECTED TO A VARIABLE UNIDIRECTIONAL CONTROL SIGNAL SOURCE, MEANS FOR DERIVING A UNIDIRECTIONAL VOLTAGE FROM SAID AC SOURCE AND APPLYING SAID LAST NAMED SIGNAL AS AN OPERATING BIASING POTENTIAL TO SAID TRANSISTOR, MEANS FOR APPLYING SAID CONTROL SIGNAL TO SAID EMITTER TO PRODUCE A PULSE TRAIN OUTPUT FROM SAID TRANSISTOR IN WHICH EACH OF THE PULSES COMPRISING SAID TRAIN RESPECTIVELY OCCUR DURING DISCRETE HALF CYCLES OF SAID AC SOURCE OUTPUT, THE TIMES OF OCCURRENCE OF SAID PULSES WITHIN SAID HALF CYCLES BEING DETERMINED BY THE MAGNITUDE OF SAID CONTROL SIGNAL, MEANS FOR APPLYING SAID PULSES TO SAID GATE ELECTRODES TO RENDER SAID RECTIFIERS ALTERNATELY CONDUCTIVE IN SUCCESSIVELY OCCURRING HALF CYCLES SUBSTANTIALLY SIMULTANEOUSLY WITH THE OCCURRENCE OF SAID PULSES, MEANS FOR APPLYING THE OUTPUTS OF SAID GATE CONTROLLED RECTIFIERS TO SAID LOAD AND MEANS CONNECTED ACROSS SAID LOAD FOR DERIVING A UNIDIRECTIONAL SIGNAL AND NEGATIVELY FEEDING BACK SAID LAST NAMED SIGNAL TO SAID EMITTER TO PROVIDE AN AC VOLTAGE APPLIED TO SAID LOAD WHICH VARIES WITH SAID CONTROL SIGNAL TO PRODUCE A LUMINESCENCE IN SAID LOAD WHOSE APPARENT INTENSITY VARIES LINEARLY WITH THE MAGNITUDE OF SAID CONTROL SIGNAL.