| 摘要 |
PURPOSE:To obtain stable resonant conditions and also to prevent stress from falling on a switching element by determining the on-time of the switching element, based on the inclination of voltage waveform at both ends of the element. CONSTITUTION:For an inverter device, parallel resonant circuits C and L and a series circuit of switching elements Q1 and Q2 are connected to both end sides of a DC power source E, and these elements Q1 and Q2 are controlled to turn on or turn off by the control signal from a control circuit 1 so as to supply high frequency power to a discharge lamp l. And a change rate detection circuit 4, which detects the change tate by detecting the voltage at both ends of the switching elements Q1 and Q2, and an on-timing setting circuit 5 are provided. As a result, the control circuit 1 can turn on the element Q2 at the point of time when the voltages at both ends of the switching elements Q1 and Q2 become minimum, whereby stable resonant conditions can be obtained. |
