| 摘要 |
The object of the present invention is an electronic ballast for a fluorescent lamp, which is of simple structure and hence of low production and marketing costs, and which, due to its structure, can be used with any conventional light dimmer. The major particularity of this ballast is that it has a dual mode of operation by which, in a first stage, it primes the arc lamp, and, in a second stage, supplies continuouly the lamp with the current source. This ballast includes particularly a dual-mode oscillator circuit comprising a tuned circuit formed of an inductive transformer for transmitting a mains supply power to the fluorescent lamp, and a tuning capacitor to the terminals of which the fluorescent lamp is connected, this tuning capacitor producing the voltage required for the priming of said lamp; a saturable transformer connected to the tuned circuit for setting the switching frequency, and a set of switching transistors suitably connected to the terminals of the saturable transformer. The ballast also includes a starting circuit for inducing a pulse at the base of one of the two switching transistors to start the oscillator circuit; and a storage circuit for storing energy in order to maintain the oscillator circuit operational between each supply alternation of the mains. |
