PURPOSE: To reduce the staining of a fixing roller by switching one of conditions of electrostatic charging, development, and transfer at the time of half-fixation mode and making the amount of developing toner stuck on a photosensitive body smaller than that in a normal fixation mode.
CONSTITUTION: A switching means 34 is connected through a varistor 33 to a grid electrode 32 arranged between the corona wire 31 of an electrostatic charger 6 and the photosensitive body 5 and the switching means 34 is connected to a CPU as a control means. Then when, for example, the half-fixation mode is selected with a mode selection key, part of the varistor is short-circuited through the operation of the switching means 34 to hold an electrostatic charging potential lower than that in the normal mode. Thus the electrostatic charging potential to the electrostatic charger 6 is lowered to make the amount of developing toner stuck on the image part on the photosensitive body 5 at the time of development smaller than that in normal fixation mode. The amount of developing toner transferred to transfer paper is therefore decreased. Consequently, the quality of a copy image is improved, the reliability is increased, and maintenance intervals become long.
KATO SHUNJI
KATO EIICHI
NONAKA MITSUHIRO
SHIMIZU KENICHI
