| 摘要 |
PURPOSE:To evade the effect of stray capacitance of a voltage dependency resistive element being a load of a switching section by adding 2 diodes to the driving circuit. CONSTITUTION:A short-circuit current of a FET 64 flows to a high voltage power supply 4 via a fuse 51, a diode 32 and a varister 41 without being supplied to a +Vcc terminal 101 because of the presence of a diode 33, the fuse 51 is blown out after a prescribed time to protect a switching section 100. On the other hand, the stray capacitance of the varister 41 is charged up to +Vcc via a diode 33 at the time of normally operating and when a driving signal voltage of +V is supplied to a gate of the FET 64, the stray capacitor of the varister 41 is not charged through the diode 32. Furthermore, when driving signal voltage of -V is applied to the gate of the FET 64, the charge in the stray capacitor of the varister 41 is not discharged because of the presence of the diode 32. Then, the effect of the stray capacitor of the voltage dependency resistive element is prevented. |
