| 摘要 |
PURPOSE:To realize cost reduction at the part of fixing unit by deciding whether AC input voltage is higher than a predetermined reference voltage, subjecting the input voltage to half-wave rectification if the former is higher otherwise subjecting to double voltage rectification and applying an identical voltage, respectively, on one fuser lamps. CONSTITUTION:When a commercial power supply 21 is approximately at 100V, a Zener diode(ZD) 38 is not turned ON hence a first thyristor 41 is not turned ON. Consequently, a second thyristor 43 functions similarly to a normal diode. DC voltages having respective polarities are thereby fed on a power supply line 45 to a double voltage rectifying circuit 25 every time when the polarity of power supply changes thus charging capacitors 54, 55 with every half wave. When the commercial power supply 21 is approximately at 200V, the ZD 38 turns ON to cause the first thyristor 41 to turn ON thus turning the second thyristor 43 ON. Under that state, only a third diode 44 performs rectification and only the capacitor 54 is charged. |
