Patent ID: 8897675

Claim:
An image forming apparatus comprising: a) an imaging member having a charge retentive-surface for developing an electrostatic latent image thereon, wherein the imaging member comprises: a substrate, and a photoconductive member disposed on the substrate; b) a bias charge roller for applying an electrostatic charge on the charge retentive surface to a predetermined electric potential wherein the charging unit comprises a first circumferential area in contact with the photoconductive member (CC [contact] ) and a second circumferential area (CC [non-contact] ) spaced a distance of from about 1 μm to about 1 mm from the photoconductive member; and c) a power supply for supplying an oscillating voltage signal to the bias charge roller wherein the oscillating voltage signal has a frequency Am[f AC ], measured in kHz, and an amplitude Am/V[ AC ], measured in kV, wherein a relationship (CC [contact] /CC [non-contact] )≦(Am[f AC ]/Am[V AC ])≦(CC [non-contact] /CC [contact] ) is met.