| 摘要 |
PROBLEM TO BE SOLVED: To prevent adverse effect on a drum photosensitive material in a thrust area when a developing roller being thrusted to the drum photosensitive material is stopped for a long time. SOLUTION: A drum photosensitive material 10 and a developing roller 11 with both outer peripheries in mutual contact are rotated in mutually opposite directions. Toner 15 is deposited onto the outer periphery of the developing roller 11 to thrust the developing roller 11 to the drum photosensitive material 10 on which a static latent image is formed, so that a toner image can be developed on the drum photosensitive material 10. In such a developing device, the elastic layer 11a of the developing roller 11 consists of a ternary copolymer rubber layer formed of ethylene-propylene-nonconjugated diene components using sulfur or sulfur compound as cross-linking agent, an iodine number for the ternary copolymer rubber layer being 20 or more or a Moony viscosity ML1+4 being 60 or more at 100 deg.C. |
