Patent ID: 6608451
Filing Date: 2003-08-19
Classification: H05B,Y10S

Abstract:
A ballast circuit for serially connected high intensity discharge lamps comprising:an electromagnetic ballast arrangement receptive of an input power signal, providing an output ballast voltage for driving the lamps, and providing an open circuit ballast voltage when the lamps are disconnected from the arrangement; and an ignitor circuit connected to the ballast arrangement and to each lamp for starting all of the lamps and for producing at least one ignitor pulse of high voltage and high frequency compared to the open circuit ballast voltage to start each lamp, the ignitor circuit comprising: a voltage-breakover device; a first capacitor with a first lead coupled to a first lead of the voltage-breakover device; a resistor with a first lead coupled to the first lead of the voltage-breakover device and the first lead of the first capacitor; a pulse autotransformer associated with each subsequent serially connected high intensity discharge lamp after a first lamp of the plurality of serially connected lamps, the autotransformer having a winding connected between two serially connected lamps and a tap; and a second capacitor with first and second leads, wherein the first lead is coupled to a second lead of the resistor and the second lead is coupled to the tap of the pulse autotransformer.