Image forming apparatus

An image forming apparatus comprising:

• an image bearing member;
• a developer carrying member provided in contact with the image bearing member and serving to develop an electrostatic image formed on the image bearing member with a non-magnetic one-component developer, the developer carrying member being adapted to carry the developer;
• and
• a developer regulating member for regulating a thickness of a layer of the developer carried on the developer carrying member, wherein a DC voltage is applied to the developer carrying member, and a superimposed voltage formed by superimposing a DC voltage and an AC voltage is applied to the developer regulating member, 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:
• 4.2×v≦f≦2500 and
• 2.2×106≦E≦5.2×106.