| 摘要 |
PURPOSE:To control the preheating voltage to fluorescent lamp filaments with high accuracy and good responsiveness. CONSTITUTION:A power source is turned on or off by an oscillator 1 provided on the primary side to drive a fluorescent lamp lighting inverter transformer T2, and the high-frequency voltage outputted from the secondary side is fed to a fluorescent lamp FL1 via a fluorescent lamp lighting current limiting inductance L1. A diode bridge DB1 and a transistor Q2 are connected to both ends of the fluorescent lamp FL1, and the fluorescent lamp FL1 is turned on or off via the control of the transistor Q2 by a fluorescent lamp control circuit 2. The outputs from the secondary windings S1, S2 of a filament preheating converter transformer T1 are rectified, smoothed, and fed to preheat the filaments 11, 12 of the fluorescent lamp FL1. A transistor Q1 is turned on or off by a preheating voltage control circuit 3 to control the input to the primary winding P1 so that the output detection value from a detecting winding P2 provided on the filament preheating converter transformer T1 is stabilized. |
