Electronic ballast circuit fot fluorescent lamp

Abstract

An electronic ballast circuit for fluorescent lamp is composed of anti-interference circuit, rectifier, filter, frequency-changing circuit, and resonant circuit. A main resonant capacitor is connected between the negative end of filter and one end of fluorescent lamp where the resonant inductor in resonant circuit is connected. Said capacitor and resonant inductor constitute a main resonant circuit, whose Q value is not affected by filament resistance at both ends of lamp tube, so raising the voltage applying across the both ends of lamp tube. A preheating circuit is parallelly connected with main resonant capacitor for preheating filament befor starting it.

Description

technical field [0001] The invention relates to a circuit device for igniting or controlling a discharge lamp, in particular to an electronic ballast circuit for a fluorescent lamp. Background technique [0002] The electronic ballast circuit for fluorescent lamps usually adopts a series resonant circuit, that is, a resonant circuit composed of a capacitor, a fluorescent lamp filament resistance, and an inductance in series to ignite the lamp after generating high voltage at both ends of the fluorescent lamp. A rectification circuit, a filter circuit, and a frequency conversion circuit are sequentially connected, and an anti-interference circuit is also connected before the rectification circuit of the electronic ballast circuit of some fluorescent lamps. In this kind of electronic ballast circuit, the influence of the filament resistance of the fluorescent lamp will reduce the Q value of the series resonant circuit circuit, the resonant voltage cannot meet the requirements ...

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Problems solved by technology

In this kind of electronic ballast circuit, the influence of the filament resistance of the fluorescent lamp will reduce the Q value of the series resonant circuit circuit, the resonant voltage cannot meet the requirements of the starting voltage of the fluorescent lamp, and it becomes very difficult to start the fluorescent lamp. If the filament of the fluorescent lamp Resistor short-circuit direct ignition, although the lamp tube can be illuminated, but the filament is not preheated, that is to say, direct cold cathode ignition will greatly shorten the life of the fluorescent tube filament, moreover, this existing fluorescent lamp The electronic ballast circuit is suitable for power supply with a power supply voltage of 200-240V. When the power supply voltage is 100-120V, its resonance voltage cannot meet the normal ignition of fluorescent lamps.

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