| 摘要 |
PURPOSE:To make secure lighting of a discharge lamp possible by employing a detector circuit for detecting the voltage of the discharge lamp and a preheating detection circuit thereby securely detecting that the discharge lamp is in a preheated condition at the time of starting the discharge lamp and controlling the output of an inverter circuit against a lighting circuit. CONSTITUTION:There are provided a detector circuit 18 for detecting the voltage of a discharge lamp 17 connected to an output side of an inverter circuit 3, a protection circuit 25 which works when a divided voltage of the voltage rectified and smoothed with the detection circuit 18 is above a specified value, a preheating time detector circuit 24 which works with a voltage lower than an operation setting voltage of the protection circuit 25 and detects the preheating time of a discharge lamp 17, and control circuit 30 which adjusts, attenuates or stops the output of the inverter circuit 3 to a lighting circuit 8. This makes it possible to suitably control the outputs of the inverter circuit 3 at the time of both lighting and preheating of the discharge lamp 7. |
