| 摘要 |
PROBLEM TO BE SOLVED: To provide a developing device and an image forming apparatus, in which an output value from a permeability sensor is stable and accurate toner concentration control can be performed. SOLUTION: The permeability sensor 26 for measuring magnetic permeability of two-component developer in a toner development supply part 25 opposed to a developing roller 24 is disposed on a bottom part 25a of the toner development supply part 25. The developing roller 24 has a rotating developing sleeve 242 having hollow cylindrical shape, and magnetic poles (243a to 243c) fixed inside the developing sleeve 242. The magnetic pole 243c inside the developing sleeve 242 is disposed at a position where it is opposed to the permeability sensor 26 disposed on the bottom part 25a of the toner development supply part 25. COPYRIGHT: (C)2011,JPO&INPIT
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