| 摘要 |
PURPOSE:To ensure that circuit parts are protected during failures and to prevent malfunctions. CONSTITUTION:Energy accumulated in an oscillation coil Li or the like, while a switching element Q1 is on, is used to resonate a resonance circuit when the switching element Q1 is off. High frequency power obtained by the resonance of the said resonance circuit is supplied to an electric discharge lamp La. A control circuit 1 is used to allow the said switching element Q1 to be ready for operation for a certain time since the end-to-end voltage of the switching element Q1 decreases to a specified voltage. An electric current detection circuit 2 is used to detect electric currents flowing through the switching element Q1. When the said electric current reaches a current restriction level, a current restriction circuit 4 controls the control circuit 1 to forces the switching element Q1 to turn off. A level adjustment circuit 5 varies the current restriction level based on the operation of the electric discharge lamp La. |
