| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a high durability charging roller which reduces variation and deviation of a charging gap while maintaining the charging gap with a high degree of accuracy even if the use environment and use situation change with a two-component developer, and to provide an image forming apparatus using the charging roller. <P>SOLUTION: In the image forming apparatus, the charging roller 14 consists of a metallic cylinder 14a, a charging member 14b comprising a conductive resin integrated with an outer periphery of the metallic cylinder 14a, and gap holding members 14c comprising an insulating resin attached to both ends of the charging member 14b, a magnetic carrier has a volume resistivity in a range of 12-16 [log (Ωcm)], and the image forming apparatus has a means to increase a surface potential (Vd-Vb) represented by the difference between a surface part potential Vd of an image bearing member and a developing bias Vb in accordance with the increase of the number of prints or drive time from the beginning of use of the image forming apparatus. <P>COPYRIGHT: (C)2008,JPO&INPIT</p> |
