Developing apparatus and image forming apparatus having first and second voltages applied to a developing satisfying predetermined relationships

An image forming apparatus comprising:

• an image bearing member for bearing a latent image;
• a developer bearing member for bearing and carrying a developer to a developer area;
• developer borne on said developer bearing member, wherein said developer has a weight average particle size not exceeding 6.5 μm and contains an external additive of a charging polarity opposite to that of said developer;
• and
• voltage application means for applying a voltage to said developer bearing member, wherein said voltage including at least a first voltage V1 for acting on said developer in a direction from said developer bearing member toward an image bearing member and a second voltage V2 for acting on said developer in a direction from said image bearing member toward said developer bearing member, and a charged potential VL of said image bearing member, a latent image potential VD, a distance H between said developer baring member and said image bearing member, and wherein said voltages V1 and V2 satisfy a following relationships:
• |V1−VL|/H≦3.7×10−6 V/m;
• and
• |V2−VD|/H≦2.9×10−6 V/m.