| 摘要 |
PROBLEM TO BE SOLVED: To use the output signal of a common oscillation circuit as a control signal supplied to a chopper driving circuit and an inverter driving circuit and improve the starting performance of a discharge lamp. SOLUTION: An AC power source AC is connected to a discharge lamp FL through a rectifier DB1, a chopper 1 and an inverter 2. An output signal that is obtained by passing the output signal of a common oscillation circuit 5 through a duty ratio control circuit 6 is used as a control signal supplied to a chopper driving circuit 3 and an inverter driving circuit 4 which drive and control a chopper 1 and an inverter 2, respectively. When the discharge lamp FL is started, the on-duty of a switching element Q1 constituting the chopper 1 is increased. The output signal of the duty ratio control circuit 6 is supplied to the chopper driving circuit 3 through an on-duty control circuit 7 and the onduty control circuit 7 controls the on-duty of the switching element Q1 variably by monitoring the output voltage value of the chopper 1. |
