Patent ID: 6072977
Filing Date: 2000-06-06
Classification: G03G

Abstract:
The image forming apparatus comprising:a photo-conductive member configured to carry a toner image on a surface of the photo-conductive member;a transfer roller configured to press against said surface of the photo-conductive member and transfer said toner image to a sheet, said transfer roller including a bias applying axis and an elastic layer engaged with a surface of the bias applying axis, said elastic layer having edge portions and a middle portion between the edge portions of the elastic layer; anda bias applying device configured to apply a bias voltage to said bias applying axis;wherein said elastic layer is thicker at the two edge portions than at the middle portion;wherein said elastic layer includes an electrically conductive powder dispersed and compressed therein such that an average distance between particles of the powder is smaller at the edge portions than at the middle portion;wherein said bias-applying axis has a constant diameter along a width of the bias-applying axis;said elastic layer includes two large diameter portions respectively located at the edge portions of the elastic layer and having diameters larger than a diameter of the middle portion; andwherein the diameters of the two large diameter portions increase toward respective edges of the transfer roller.