| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a developing device and an image forming apparatus which are used for a long term only by replenishing toner without replacing parts even when used as a high speed apparatus. <P>SOLUTION: The developing device includes: a developer t, a developer carrier 41, and a developer restricting member 45 arranged at a position separated from the developer carrier 41. Magnetic toner t of one component system is used as the developer, wherein a volume average particle size is 6.0-10.0 μm, the proportion of the 5 μm or less particle size is 6.0-10.0 vol.%, and saturation magnetization is 16-27 Am<SP>2</SP>/kg. The developer carrier 41 includes a freely rotatable development sleeve 41a; and a magnet roller 41b which is incorporated into and fixed to the development sleeve 41a. In the magnet roller 41b, a first magnetic pole S<SB>2</SB>with a magnetic force of 800×10<SP>-4</SP>to 1,000×10<SP>-4</SP>T is arranged at the opposite position of the developer restricting member 45, and a second magnetic pole N<SB>2</SB>with a polarity reverse to that of the first magnetic pole S<SB>2</SB>, and with the magnetic force of 300×10<SP>-4</SP>to 500×10<SP>-4</SP>T is arranged at the position of 70-90° from the opposite position in the reverse direction of a development sleeve rotating direction. A magnet 45a with the magnetic force of 350×10<SP>-4</SP>to 600×10<SP>-4</SP>T is adopted as the developer restricting member 45. <P>COPYRIGHT: (C)2003,JPO |
