Patent ID: 8129920
Filing Date: 2012-03-06
Classification: H05B

Abstract:
1. A discharge lamp lighting device comprising: an inverter part including at least one or more switching elements connected to an output end of a DC power source; a control circuit for controlling switching in the inverter part; a load circuit including a resonance circuit connectable to a discharge lamp with a thermionic cathode and being connected to an output end of the inverter part; a preheating circuit for preheating a filament of the discharge lamp; and a detection circuit for detecting an electrical characteristic associated with a filament resistance of the discharge lamp, wherein an electrical characteristic associated with a filament resistance are detected by the detection circuit to control a preheating amount for the filament, in accordance with a filament resistance value and a determined preheating time, so that a ratio of a hot resistance to a cold resistance in the filament falls in a range of 4.0 or more and less than 5.5.