Controlled high voltage lighting system for gaseous-discharge lamps

Abstract

A lighting system for gaseous-discharge lamps for applying high voltage pulses to ignite the lamp and for discontinuing the application of high voltage pulses when the lamp is operating. The system includes ballast facilities having an inductive portion, and a control circuit which is responsive to a voltage induced in the inductive portion when the gaseous-discharge lamp operates. When the control circuit is operative, the pulsing portion of the system is disabled. The system is arranged so that the components of the control and pulsing circuits are not subjected to the application of high voltage pulses at any time.

What is claimed is: 
     
       1. A gaseous-discharge lamp lighting system comprising: a gaseous-discharge lamp;   ballast means including an inductive portion operatively connected to said lamp;   a voltage source connected to said ballast means;   pulsing means for inducing pulses in the inductive portion of said ballast means to ignite said lamp including: a first series combination of a gated switch means and a capacitance connected to one end of said inductive portion of said ballast means; and   charging means for applying a gating signal to said switch means at a predetermined time at least once every cycle to render said switch means conductive;     control means for inductively sensing current flow through the inductive portion when said lamp is ignited including gated bilateral switch means which is triggered by voltage induced in said winding to conduct during operation of said lamp and render said pulsing means inoperative.   
     
     
       2. A gaseous discharge lamp lighting system comprising: a gaseous discharge lamp;   ballast means including an inductive portion operatively connected to said lamp;   a voltage source connected to said ballast means;   means for inducing pulses in the inductive portion of said ballast means to ignite said lamp;   control means for inductively sensing current flow through the inductive portion when said lamp is ignited for disabling said pulsing means;   a first series combination of a gated switch means and a capacitance connected to one end of said inductive portion of said ballast means;   charging means for applying a gating signal to said gated switch means at a predetermined time at least once every cycle to render said switch means conductive;   a second series combination of a resistance and a capacitance connected in parallel across said first series combination, and   switch means having a predetermined threshold voltage connected between the juncture of said resistance and capacitance and the gate of said gated switch means.   
     
     
       3. A lighting system as set forth in claim 2 wherein a resistance is connected across the capacitance of said first series combination to discharge said capacitance at a predetermined rate. 
     
     
       4. A lighting system as set forth in claim 3 wherein said predetermined rate is selected so that only one high voltage pulse is applied to the lamp each .[.positive.]. .Iadd.negative .Iaddend.half-cycle. 
     
     
       5. A lighting system as set forth in claim 2 wherein said gated switch means is a controlled rectifier and a diode is serially connected therewith. 
     
     
       6. A lighting system as set forth in claim 1 wherein said ballast means is an autotransformer having a primary winding and a secondary winding and wherein said inductive portion is a portion of said secondary winding, and including a power factor capacitance connected across said primary winding. 
     
     
       7. A lighting system as set forth in claim 1 wherein said pulsing means further includes: said charging means including a second series combination of a resistance and a capacitance connected in parallel across said first series combination; and   switch means having a predetermined threshold voltage connected between the juncture of said resistance and capacitance of said second series combination and the gate of said gated switch means.   
     
     
       8. A lighting system as set forth in claim 7 wherein said gated bilateral switch means is connected across said capacitance of said second series combination, and having its gate terminal serially connected to said winding so that upon conduction of said lamp a gating voltage is applied to said gated bilateral switch means to bypass said capacitance of said second series combination. 
     
     
       9. A lighting system as set forth in claim 8 wherein a resistance is connected across the capacitance of said first series combination to discharge said capacitance at a predetermined rate. 
     
     
       10. A lighting system as set forth in claim 1 wherein said ballast means includes a constant voltage transformer having a primary winding connected to said voltage source and a secondary winding connected across said lamp, and an inductor serially connected to said lamp. 
     
     
       11. A lighting system as set forth in claim 10 wherein said constant voltage transformer further includes an isolated capacitor winding to regulate the voltage applied to said inductor. 
     
     
       12. A gaseous-discharge lamp lighting system comprising: an AC voltage source;   a gaseous-discharge lamp;   autotransformer ballast means having a primary winding connected to said voltage source and a secondary winding connected to said lamp, said secondary winding having a first portion with a first number of turns and a second portion with a substantially greater number of turns;   pulsing means including:   a first series combination of a gated switch means and a capacitor connected to one end of said first portion; and   charging means for applying a gating signal switch means at a predetermined time at least once every cycle to render said switch means conductive thereby applying pulses to ignite said gaseous-discharge lamp; and   control means for detecting current flow in said first portion of said said secondary winding when said gaseous-discharge lamp is operating for disabling said pulsing means.   
     
     
       13. A lighting system as set forth in claim 12 wherein said control means includes a gated bilateral switch having its gate terminal connected to said first portion through a series combination of a diode and a limiting resistance, said gated bilateral switch being conductive when a voltage is induced said first portion during operation of said lamp, the conduction of said gated bilateral switch disabling said pulsing means. 
     
     
       14. A lighting system as set forth in claim 12 wherein: said pulsing means includes: a first resistance connected across said capacitance,   a second series combination of a second resistance and a second capacitance connected across said first series combination, and   switch means interconnecting the gate terminal of said gated switch means and the juncture of said second resistance and second capacitance; and     said control means includes:   gated bilateral switch means connected across said second capacitance and having the gate terminal thereof connected to said first portion of said secondary winding.   
     
     
       15. A lighting system as set forth in claim 14 wherein the gate terminal of said gated bilateral switch means is connected to said first portion through a series combination of a resistance and a diode. .Iadd. 16. A lighting system as set forth in claim 2, wherein: a resistance is connected across the capacitance of said first series combination to discharge said capacitance at a predetermined rate; and   said predetermined rate is selected so that one high voltage pulse is applied to the lamp each negative half-cycle of the input voltage. .Iaddend.