| 摘要 |
The invention realizes a uniform toner coating on a developing roller, thereby preventing a density unevenness and a toner dripping and suppressing a developing roller set mark image in a contact developing method, by conditions that the DC voltage applied to the developer regulating member is the same as the DC voltage applied to the developer carrying member or at a side of a charging polarity of the developer with respect to the DC voltage applied to the developer carrying member; and a frequency f (Hz) and a peak electric field strength E (V/m) of the AC electric field formed by the AC voltage between the developer regulating member and the developer carrying member, and a peripheral speed v (m/s) of the image bearing member satisfies conditions: <?in-line-formulae description="In-line Formulae" end="lead"?>4.2xv<=F<=2500 and <?in-line-formulae description="In-line Formulae" end="tail"?> <?in-line-formulae description="In-line Formulae" end="lead"?>2.2x10<SUP>6</SUP><=E<=5.2x10<SUP>6</SUP>.<?in-line-formulae description="In-line Formulae" end="tail"?>
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