| 摘要 |
PURPOSE:To carry out the lighting and the dimming without generating noise by lighting a fluorescent lamp with an auxiliary starting capacitor stably even at a low temperature, and carrying out the dimming of the fluorescent lamp by the switching operation of a semiconductor switching circuit. CONSTITUTION:Where the voltage induced in the primary winding N1 of an oscillation transformer 5 in the oscillation operation of an inverter circuit 4 is made as Va, the voltage induced in the secondary winding N2 is made as Vb, and the terminal voltage of an auxiliary starting capacitor 20 is made as Vc, the impedance of the auxiliary starting capacitor 20 is set to apply a high earth voltage corresponding to a high voltage V as V=Va+Vb-Vc>Vb to the fluorescent lamp 2 to light it. When the secondary voltage of the oscillation transformer 5 is raised by the auxiliary starting capacitor 20, the fluorescent lamp 2 is lighted stably even at a low temperature. Consequently, a perfect no contact system of auxiliary starting circuit of a fluorescent lamp is realized, and a long service life without noise is obtained. |
