LIGHTING CIRCUIT FOR AUTOMATIC FLICKERING FLUORESCENT LAMP

摘要

PURPOSE: To extend service life of a fluorescent lamp even if it is continuously turned ON/OFF by releasing a resonance circuit resonated before illuminating the fluorescent lamp from the resonated state after it is lit. CONSTITUTION: When a DC voltage is applied to both ends of a first and a second resonance circuits, a switch circuit turns ON one of the first and second switches SW1 and SW2. For example, when the switch SW1 is turned ON initially, capacitors C1 and C2 controlled in the first resonance circuit is charged, and if a half period of the resonance frequency is passed, a switch control circuit turns OFF the switch SW1 and turns ON the switch SW2. A load charged with the capacitors C1 and C2 is discharged via an inductor L1 and the switch SW2, a capacitor C3 is charged with a DC power supply, and the capacitors C1 and C2 are charged in opposite direction. The capacitors C1 and C3 are discharged, the capacitors C1 and C2 are charged, this operation is repeated, and turning ON/OFF the fluorescent lamp is performed by an alternate power supply.