HIGH VOLTAGE POWER SOURCE CIRCUIT FOR ELECTROSTATIC COPYING MACHINE WITH BACKUP CIRCUIT

摘要

PURPOSE:To enable to effectively drive a photocoupler even at high voltage side shortcircuiting time by providing an amplifier for driving the photocoupler and another coil becoming a power source of a backup circuit in addition to the secondary coil in a high voltage transformer. CONSTITUTION:The output of a chopper type switch regulator 15 is applied to an oscillator 16, and a high voltage is applied to an electrostatic application unit of an electrostatic copying machine through a high voltage transformer 17 and a high voltage rectifier 21. The output current is detected by a detector 22, an amplifier 24 using an auxiliary coil 20 added to the secondary side of the transformer 17 as a power source to operate photocouplers 27, 33, a regulator 15 is controlled, and connected to a photocoupler light emitting unit 27 by providing a backup circuit 28 controlled by the output of the detector 22. Accordingly, even when the high voltage such as high voltage side shortcircuit suppressed, sufficient current can be supplied to the photocouplers, thereby accurate control is enabled.