| 摘要 |
PURPOSE: To stably prevent the scattering of toner by pushing back the toner scattered from the developing sleeve of a developing device toward the developing sleeve. CONSTITUTION: An electrode 16 for a conductive member is provided to face the developing sleeve 3 in the lower part of the opening part of a developing unit 8 in which the developing sleeve 3 is arranged and a DC voltage having the same polarity as that of the charge of the toner is applied to the electrode 16 between it and the developing sleeve 3 to which a developing bias is applied. Then, an electric field E (V/m) formed by the DC voltage and the DC component of the developing bias and the charge quantity q (C/kg) of the toner scattered from the developing sleeve 3 are set so as to satisfy 6×10<2> (N)<=|qE|<1.1×10<3> (N). Thus, pushing back force can be exerted on the toner scattered from the developing sleeve 3 by the electric field, so that the electric breakdown of the sleeve 3 never occurs. |
