Starter for minimizing damage to lamp electrodes of a discharge lamp at startup

Abstract

A starter for a discharge lamp is disclosed for operation from an AC supply voltage. The starter comprises a first terminal for connection to a first lamp electrode, a second terminal for connection to a second lamp electrode, a switching element coupled between the first and second lamp electrode during operation, a control circuit coupled to a control electrode of the switching element for generating a control signal for rendering the switching element conductive and thereby allowing an AC preheat current with period T to flow through the lamp electrodes and for subsequently rendering the switching element non-conductive to generate an ignition voltage pulse between the lamp electrodes. The starter advantageously inflicts only a relatively small amount of damage to the electrodes of the discharge lamp by means of ignition voltage pulses that are applied to the discharge lamp before its electrodes are sufficiently heated (i.e., during a warm-up period) by applying the ignition voltage pulses in the direct vicinity of a zero-crossing of the AC preheat current.