| 摘要 |
PURPOSE:To decrease the torque between a developing roller and a toner layer forming blade, prevent the deterioration of an image due to the filming of a toner, and provide a good image over a long period by dispersively depositing glass beads having the grain size smaller than the grain size of the toner on the surface of the elastic body layer of a developing roller. CONSTITUTION:A developing roller has a two-layer structure of an elastic body 102b and a surface conducting layer 102c around a carrier 101a made of a metal shaft, and glass beads 102d having the grain size smaller than that of toner grains are dispersively deposited on the surface of the surface conducting layer 102c. The density of the glass beads 102d is 1.1-1.5g/cm<3>, and they are dispersed to have the surface coverage of 20-60&. When the surface coverage becomes higher than 60%, grains are brought into contact with each other, thus causing the situation like the existence of apparently large insulating grains. When the toner on these grains is developed, charges have no escape position, and the subsequent development is adversely affected. When the surface coverage is below 20%, the starting torque is made large. |
