Patent ID: 6114810
Filing Date: 2000-09-05
Classification: H05B

Abstract:
An electronic ballast circuit for a fluorescent lamp having filaments, comprising:an anti-interfering circuit, a rectifying circuit, a filtering circuit, a frequency-converting circuit and a series resonant circuit connected sequentially,said series resonant circuit consisting of a first resonant capacitor, the resistance of the filaments of said fluorescent lamp and a resonant inductor connected in series,said fluorescent lamp having a first end and a second end,wherein a second resonant capacitor (C4) is directly connected between said first end of said fluorescent lamp which is connected with said resonant inductor (L1) in said series resonant circuit and a negative end of said filtering circuit, so that said resonant inductor (L1) and said second resonant capacitor (C4) constitute a main resonant circuit, and, in the high frequency AC loop,wherein voltage across both ends of said second resonant capacitor (C4) being the starting voltage of said lamp, andwherein a preheating circuit is connected in parallel between both ends of said second resonant capacitor (C4) in said main resonant circuit, said preheating circuit being an integrally sealed assembly.