| 摘要 |
PURPOSE:To enhance the circuit efficiency and to prevent an undesirable influence exerted on a screen due to a turn-on switch operation of a MOSFET by executing a stabilizing operation of a high voltage output voltage by controlling a turn-off time point of the MOSFET in a period in which a reverse current is flowing to a driving power source through a low voltage coil from a resonance capacitor or a damper diode side. CONSTITUTION:To one end side of a low voltage coil of a fly-back transformer 11, a MOSFET17 and a driving power source 18 are connected in series, and to the MOSFET17, a diode 20 and a charge capacitor 21 are connected in parallel. Between the other end side of the low voltage coil 12 and a ground line, a parallel circuit of a transistor 13, a damper diode 14 and a resonance capacitor 15 are connected. To a gate of the MOSFET17, a driving pulse signal whose pulse width becomes narrow as a drop amount of a high voltage output voltage becomes large, is applied. |
