| 摘要 |
PROBLEM TO BE SOLVED: To provide an image forming apparatus suppressing an abnormal transfer image in transferring a toner image. SOLUTION: A color copying machine 1 comprises a photoconductor drum 2a, a toner cartridge 5a, a developing apparatus 6a, a primary transfer roller 37a forming a primary transfer nip N1a between the photoconductor drum 2a and the primary transfer roller 37a, and a roller driving device 39a moving the primary transfer roller 37a to regulate transfer pressure. Toner has a first state in which volume resistivity in the toner is maintained high in a low electric field power zone having weaker electric field power than predetermined electric field power, a second state in which the volume resistivity is maintained low in a high electric field power zone having an electric field power stronger than the predetermined electric field power, and a transition state in which the volume resistivity changes with a steep gradient from the high resistivity to the low resistivity as electric field power becomes strong in an intermediate electric field power zone between the low electric field power zone and high electric field power zone including the predetermined electric field power. COPYRIGHT: (C)2009,JPO&INPIT |
