Semi-contact bias charge roller

There is described an image forming apparatus including an imaging member having a charge retentive-surface for developing an electrostatic latent image thereon, a substrate and a photoconductive member disposed on the substrate. A bias charge roller for applying an electrostatic charge on the charge retentive surface to a predetermined electric potential is included in the image forming apparatus. The bias charge roller includes 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 1 μm to 1 mm from the photoconductive member. The image forming apparatus includes a power supply for supplying an oscillating voltage signal to the bias charge roller wherein the oscillating voltage signal has a frequency Am[fAC] and an amplitude Am[VAC]. The following relationship is met: (CC[contact]/CC[non-contact]) (Am[fAC]/Am[VAC]) (CC[non-contact]/CC[contact]) by the image forming apparatus.