IMAGE FORMING DEVICE

摘要

PURPOSE:To make an image forming device small-sized and low-cost by sharing a partial power source of bias power sources among plural developing devices. CONSTITUTION:A power source 39 applies a bias voltage including an oscillating voltage component as occasion demands to a developing sleeve 31 through a protective resistance 40 to generate the electric field which controls the motion of a toner between the developing sleeve 31 and an image forming body 1. This power source 39 is constituted by connecting a DC bias power source 39a and an AC bias power source 39b in series, and the bias power source 39 is shared among developing devices 5-8. The resistance value of the protective resistance 40 is changed to adjust the voltage applied to the sleeve 31.