| 摘要 |
PROBLEM TO BE SOLVED: To provide a developing roller for which rate of decay of surface potential is fast, and for which image defects due to accumulation of a charge do not occur.SOLUTION: A developing roller 10 comprises a shaft 1, an elastic layer 2 supported on an outer circumference of the shaft, and at least one layer of coated film layers 3 and 4 formed on an outer circumferential surface of the elastic layer. Volume resistivity of each of the elastic layer and the coated film layers is lower for an inner circumferential layer than an outer circumferential layer, difference in the volume resistivity of the elastic layer and the outermost coated film layer is in a range of 2.8 to 4.3 (Log&OHgr;cm), and relaxation time (τ) of the developing roller is 0.45 s or less. |
