| 摘要 |
A circuit for synchronizing the ignition in electronic ballast discharge lamps, wherein a half-bridge output stage of the electronic ballast has an upper switch and a lower switch. The lower switch is connected to a common wire of a power supply, and a high voltage impulse for igniting the lamp is generated only when the lower switch is open. The circuit includes a transformer including a first winding and a second winding magnetically coupled to each other, with the second winding having a lower number of turns than the first winding. One lead of the first winding is connectable to an electrode of a discharge lamp, and a second lead thereof is connectable to the common wire of the power supply. A diode is connected with its anode to one lead of the second winding, and with its cathode to the junction between the upper and lower switches. A second lead of the second winding is connected to a thyristor, which is connected to a first plate of a discharge capacitor, and a second plate of the capacitor is connected to the common wire, whereby a discharge current of the capacitor flows through the second winding only when the lower switch is open. |
