A charging unit in an image forming apparatus includes a charging roller that charges a photosensitive drum using a charging bias, an insulating casing surrounding the charging roller, and a metal shield member. The shield member is positioned so as to surround the casing in close contact with the outer...http://www.google.com.au/patents/US8195068?utm_source=gb-gplus-sharePatent US8195068 - Charging unit and image forming apparatus
