| 摘要 |
PROBLEM TO BE SOLVED: To provide an image forming apparatus which can perform high quality image formation by preventing a decrease in density followability in low temperature and low humidity environment and fog due to a low speed in high temperature and high humidity environment. SOLUTION: The image forming apparatus includes: a photosensitive drum 1; a developing device 7 having a developing roller 3, a developing blade 4, and a toner supply roller 5; a development bias power source 12; and a blade bias power source 14. In the image forming apparatus, the photosensitive drum 1 has a plurality of rotating speeds. Toner T whose volume average particle diameter R<SB>T</SB>(μm) is 4.0μm≤R<SB>T</SB>≤8.2μm is used. Voltages with a polarity same as that of the toner are applied to the developing roller 3 and the developing blade 4. The voltage applied to the developing blade 4 is greater in absolute value than the voltage applied to the developing roller 3. The arithmetic average roughness R<SB>D</SB>(μm) of the surface of the developing roller 3 is 0.5 or less times that of the volume average particle diameter R<SB>T</SB>(μm) of the toner. The width L of the contact between the developing blade 4 and the developing roller 3 is 0.3 mm≤L≤1.4 mm. COPYRIGHT: (C)2010,JPO&INPIT |
