| 摘要 |
<p>An electronic high-frequency operating circuit for supplying two or more gas discharge lamps, comprising a mains rectifier; a power factor correction circuit comprising a converter self-induction, a controllable power semiconductor with associated control circuit and a rectifier diode, followed by a smoothing capacitor; and a push-pull stage controlled by a control signal, which stage converts the voltage on the smoothing capacitor into an alternating voltage which is supplied to each connected lamp via an associated series circuit of a self-induction and a resonance capacitor, while the series circuits formed by these self-inductions and resonance capacitor all have the same or substantially the same resonant frequency and the lamps are connected in parallel with the resonance capacitors and means are provided which prevent direct current flowing through the lamps, said operating circuit further comprising means which, upon activation of the operating circuit, set the frequency of the control signal for the push-pull stage at a value which is above the resonant frequency and subsequently lower it gradually to approximately the resonant frequency of the series circuits, as well as detection and regulating means for monitoring the lamp voltage and, if the lamp voltage of one or more lamps exceeds a predetermined time-dependent limit value, for regulating the frequency of the control signal in such a manner that the limit value is approximately maintained. <IMAGE></p> |
