| 摘要 |
PURPOSE:To obtain sure lighting even at low temperature time by correcting operation of an inverter circuit in a direction of increasing a lamp current larger than an oscillating operation stop level of the inverter circuit in a starting process of a discharge lamp. CONSTITUTION:Operation control of an inverter circuit 1 is performed by a control circuit 3, and supply power is varied by the control to light a discharge lamp la to dim its light. In a starting process of the discharge lamp la till its lamp current is stabilized from a glow discharge through a transfer to an arc discharge, operation of the inverter circuit 1 is corrected by a correcting means A in a direction of increasing the lamp current larger than a level of stopping the oscillating operation of the inverter circuit 1 by an oscillation stopping circuit 8. Accordingly, the oscillation stopping circuit 8 is prevented from operating in the starting process of the discharge lamp la when its lamp current is decreased at low temperature time. In this way, the discharge lamp can be surely lighted even when it is started at low temperature time. |
