| 摘要 |
PROBLEM TO BE SOLVED: To detect a problem due to degradation in the condition of a two-component developer reserved in a developing device.SOLUTION: The developing device includes: a developing tank 330 reserving a two-component developer containing a toner and a carrier; a developing roller 335 supplying the toner in the two-component developer to a photoreceptor; a first magnetic permeability sensor 338, which is arranged in a developer tank bottom, at a position close to the developing roller and which detects a magnetic permeability of the two-component developer; a second magnetic permeability sensor 339, which is arranged in the developer tank bottom, at a position farther from the developing roller than the first magnetic permeability sensor, and which detects a magnetic permeability of the two-component developer; and detecting means 91 detecting a problem of the two-component developer based on a difference in the magnetic permeability detected by the first and second magnetic permeability sensors. |
