| 摘要 |
PURPOSE:To provide a discharge lamp lighting device generating high-voltage pulses using a pulse transformer and perform lighting-up as starting, with which discharge lamp is prevented from acoustic resonance phenomenon likely to occur when the impedance of the discharge lamp remains low after it is started. CONSTITUTION:The output of a pulse transformer 6 is superimposed on the output of an inverter circuit connected with a DC power supply 1, and the result is impressed on a discharge lamp 3. If a lamp current sensing circuit 9, lamp voltage sensing circuit 10, and divider circuit 11 sense that the impedance of the discharge lamp after it is started is lower than the specified level, a control circuit 12 puts on a switch 8 to shortcircuit the primary side of the pulse transformer 6 and to lessen the inductance of the secondary side. This lessens the amplitude of the natural frequency oscillating current in an LCR series circuitry composed of secondary winding of pulse transformer, a capacitor 7, and discharge lamp 3, and high-frequency oscillating components will diminish in the lamp current. As a result, the discharge lamp is prevented from occurrence of acoustic resonance phenomenon, which permits achievement of stable lighting without stall or flicker. |
