Patent ID: 6091208
Filing Date: 2000-07-18
Classification: H05B,Y10S

Abstract:
An ignitor for starting a high intensity discharge lamp, the high intensity discharge lamp receiving power from an alternating current power source via a ballast, comprising:a storage capacitor;a voltage response switching device having an anode, a gate and a switchable conductive path connected at one end thereof to a first portion of said ballast, said ballast having a tap between said first portion and a second portion of the secondary winding thereof, the other end of said switchable conductive path being connected to a first terminal of said storage capacitor, said storage capacitor having a second terminal thereof connected to said tap;at least one breakdown device connected between said anode and said gate of said voltage response switching device and being characterized by a threshold voltage, said breakdown device becoming conductive when said storage capacitor reaches said threshold voltage to place said voltage response switching device in a conductive state and allow said storage capacitor to discharge through said ballast to operate said lamp;a charging circuit for said storage capacitor comprising a pumping capacitor and at least one inductive device connected in series between said first terminal of said storage capacitor and a common return path to said alternating current power source, said charging circuit being operable to charge said pumping capacitor and to deliver energy to said storage capacitor during alternate half-cycles of said alternating current power source; anda starter circuit comprising a third capacitor, a resistor and a second breakdown device, said third capacitor and said resistor being serially connected between said lamp and said at least one inductive device, said second breakdown device being connected at one end thereof to said tap and at the other end thereof to said third capacitor, said third capacitor being charged through said resistor until said second breakdown device conducts, said third capacitor discharging through at least a portion of said ballast to generate a voltage pulse for said lamp, said at least one inductive device being operable as a choke for said starter circuit.