Patent ID: 7215911

Claim:
An image forming apparatus comprising: a photosensitive conductor for forming a developer image; a development roller for attaching a developer onto an electrostatic latent image formed on a surface of the photosensitive conductor, thereby developing the electrostatic latent image into the developer image; a developer layer regulation member for regulating a developer layer deposited onto the development roller, the developer layer regulation member being positioned adjacent to the development roller; and a subsidiary charge roller for charging the developer in the developer layer, the subsidiary charge roller being located after the developer layer regulation member in the rotational direction of the development roller such that the subsidiary charge roller comes into contact with the development roller with a predetermined pressure while forming a predetermined gap with the development roller, wherein the diameter ratio I of the subsidiary charge roller to the development roller is in the range of approximately 0.45 to approximately 0.8, and the subsidiary charge roller has a surface roughness Rz in the range of approximately 1 to approximately 15.