| 摘要 |
PROBLEM TO BE SOLVED: To eliminate variation in a resistance value in a peripheral direction and to enable excellent image formation by forming a silicone material to a columnar shape and making the difference between the maximum and minimum values of the resistance value in the peripheral direction a specific value. SOLUTION: In a transfer roller 33, a transfer part, 52 is constituted in such a manner that a semiconductive silicone material is formed to a nearly columnar shape on the circumference of a rotary shaft 51. The transfer roller 33 is placed on a stainless steel plate 53. In this state, the transfer roller 33 is rotated to move on the steel plate 53, while a fixed high-voltage charge is applied from a high-voltage power source 54. In such a way, the high-voltage charge of a discharge starting voltage or above is applied to a roller main body, to make a discharge from the periphery of the transfer part 52 uniform in the peripheral direction. Thus, in the silicone material of which the transfer part 52 is made, an oxidation state in the peripheral direction is made uniform and the difference between the maximum and minimum values of the resistance value in the peripheral direction is in the range of 0.5×one order.
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