PURPOSE: To perform constant-current control over an electrifier and prevent an overcurrent without increasing the scale of constitution by controlling the primary side of a high-voltage transformer with shield currents of a specific electrifier supplied with a high voltage from the common secondary winding of the transformer and an unspecified electrifier, and making a disconnection.
CONSTITUTION: A photosensitive body electrifier 2 as the specific electrifier which is driven with a constant current through the common secondary winding of an inverter transformer 7 and a transfer electrifier 5 as the unspecified electrifier are supplied with the high voltage. The shield current of the electrifier 2 is detected through a resistance R1 to control the primary side of the transformer 7 under the feedback control over an inverter driving circuit 8 by an error amplifier 9, etc., and the electrifier 2 is brought invariably under constant-current control even when a constant-current resistance R4 varies in impedance. On the other hand, the shield current of the electrifier 5 is detected through a resistance R2, and the supply voltage to the primary winding of the transformer 7 is cut off through a comparator 10 to prevent an overcurrent to the electrifier 5. The common secondary winding is used, so the currents of the electrifiers of a copying device are made constant without increasing the scale of the constitution and an overcurrent is prevented.
NAGAHIRA JIYOUJI
TAKAHASHI KAZUYOSHI
YOSHIHARA KUNIO
MATSUI TOSHIAKI
ISHIKAWA TADASHI
| JPS55122379A | 1980-09-20 | |||
| JPS5621157A | 1981-02-27 |