| 摘要 |
PROBLEM TO BE SOLVED: To prevent the wear of an end part of a developing roller, and leakage of the toner from the side by providing an elastic layer of non-printing area of the developing roller made of the material of higher tensile strength than that of the material of the elastic layer. SOLUTION: An elastic layer of non-printing areas 30a, 30b at each end of a developing roller 14 with which a toner regulating member is brought into contact is made of the material of higher tensile strength than that of the material of an elastic layer of a printing area 29. For instance, the printing area 29 is made of urethane rubber elastic body, and the non-printing areas 30a, 30b are made silicone rubber elastic body. The urethane rubber elastic body of 5-10kg/cm<2> in tensile strength, and the silicone rubber elastic body of 40-50kg/cm<2> in tensile strength are formed, and inserted in the prescribed dies across a metallic shaft 27 to form a developing roller 14. The diameter of the non-printing areas 30a, 30b of the developing roller 14 is slightly smaller than the diameter of the printing area 29, and a toner layer thickness regulating member is preferably abutted on only the printing area 29. |
