High power gas discharge lamp ballast for ignition and operation of lamp - uses bridge stage switched between DC mode for lamp ignition and AC mode for subsequent operation of lamp

摘要

The ballast is supplied from a DC source (B), coupled to a DC/DC converter (D), providing a stabilised and/or power regulated DC voltage (OV, -UW). The converter is coupled to a bridge stage (W) with both AC and DC modes. The DC mode is employed during ignition of the lamp (GDL), a status device (S) providing a signal upon ignition of the lamp (GDL) supplied to the bridge stage (W) via a delay device (V), so that the bridge stage (W) is switched to the AC mode after a defined delay interval. Pref. the status device responds to the detected lamp current and/or voltage, in comparison with a reference value. USE/ADVANTAGE - For high power gas discharge lamp used in automobile headlamp, preventing flicker and increasing working life.