| 摘要 |
PURPOSE:To surely detect a life end to be coped with no regard to an assortment of an inverter by detecting a lighting state by means of a discharge lamp current or voltage. CONSTITUTION:When a discharge lamp causes half-wave discharge at its life end so that a current is generated only in the solid line arrow direction, a transistor Q3 does not turn ON, and when the current flows in the broken line arrow direction, Q1 remains OFF, while capacity C0 indicates the states (a) and (b) respectively. That is, deterioration of the discharge lamp starts, the current in one direction grows large, a difference is generated in the constant of C0 at the time charge of and discharge due to a charging a circuit 6 and a discharge circuit 7 showing a voltage waveform in the middle of the states (a) and (b). When this is detected by an output control circuit 4, an action of an inverter I can be controlled in a proper state in the state where deterioration is started. |
