PURPOSE: To prevent the abnormal heat generation in the electrode portion so as to improve the safety of a fluorescent lamp by connecting the primary winding of an inductance element for the current limitation to a fluorescent lamp in series, and connecting the secondary winding of the said element between the base and the emitter of a transistor in an inverter.
CONSTITUTION: A DC current produced by a rectifier 1 and a smoothing capacitor 2 is flowed in the base of a transistor(TR)8 through a resistance 11 to make the TR8 on. At this time, the collector current of the TR8 flows from the positive electrode of the capacitor 2 to the negative electrode of which through an oscillation transformer 4 and also simultaneously through the primary winding 5A of an inductance element 5 and a fluorescent lamp 6. In addition, an electromotive force is generated in the secondary winding 5B of the inductance element 5 in the direction to make the TR8 on to keep the TR8 in on-state. When the collector current of the TR8 increases to a value larger than the product of the current amplification factor and the base current, the collector current tends to saturation, and the direction of the electromotive force in the secondary winding 5B is changed to make the TR8 off, thus the TR8 can be made instantly off.
IMAI TAKAYUKI
NOMI KAZUMASA
| JPS62108498A | 1987-05-19 |
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