Patent ID: 6724155
Filing Date: 2004-04-20
Classification: H05B,Y10S

Abstract:
An ignitor circuit for a semi-resonant ballast and lamp circuit connected to a power source, the semi-resonant ballast and lamp circuit being operable to use switching operations intrinsic to a discharge lamp to shock-excite a series-connected inductor and capacitor into an energy exchange and transfer during each half-cycle of an alternating current source providing power to the semi-resonant ballast and lamp circuit to start and maintain operation of said lamp using line voltage, the ignitor circuit comprising:a second capacitor; a capacitor charging circuit for charging said second capacitor with an offset voltage; a pulse generator circuit for generating pulses via discharging of said second capacitor to ignite said lamp when combined with said offset voltage and line voltage from said power source, said pulse generator circuit being connected at one end thereof to a first terminal of said second capacitor, said second capacitor being connected at a second terminal thereof to a first node between said inductor and a first terminal of said lamp, said pulse generator circuit being connected at another end thereof at a second node between said capacitor and said power source; wherein said pulse generating circuit is rendered ineffective for igniting said lamp when voltage across said first node and said second node increases during operation of said lamp.