High voltage discharge lamp lighting device

Abstract

A high-voltage discharge lamp lighting device provides a starting pulse voltage sufficient to turn on a high-voltage discharge lamp having terminal wire connections of variable length. A power conversion circuit is coupled to a commercial AC power source input and rectifies the AC input into a predetermined DC voltage output. A charging capacitor is coupled to the power conversion circuit. A full bridge circuit is coupled to the power conversion circuit and the charging capacitor and provides a rectangular wave AC output signal to a transformer primary winding circuit of at least a capacitor, a single switching element and a primary winding of a transformer. A low pulse voltage is induced in the primary winding and a transformer secondary winding is connected on one end to the high-voltage discharge lamp, wherein the low pulse voltage is stepped up to a high pulse voltage and applied to the high-voltage discharge lamp. A reference voltage is generated in a reference transformer winding representative of the high pulse voltage. A starting pulse equivalent value detection circuit is connected to the reference winding and detects a value associated with the reference voltage. A control circuit receives said value from said detection circuit, and variably controls at least one of a frequency of the single switching element or an ON impedance of the single switching element in association with said value, wherein said frequency or ON impedance is further associated with a starting pulse voltage sufficient to start the high-voltage discharge lamp.