| 摘要 |
PROBLEM TO BE SOLVED: To prevent surface staining (specially caused by the insufficient electrification of toner) from occurring in an electrophotographic device. SOLUTION: The electrophotographic device is provided with a means forming a reference pattern on an image carrier 1 and a reflecting density detection sensor 16 detecting the reflecting density of the reference pattern formed on the carrier 1 Besides, it is constituted so that toner concentration in a developing device 3 is controlled according to the detected result of the sensor 16. By driving the carrier 1 and the developing device 3 at a time other than the time of an image forming action, the change of toner quantity causing the surface staining on the carrier 1 is detected by the sensor 16. When the change being equal to or over a prescribed value is detected, the developing device 3 and the carrier 1 are continuously driven so as to stir developer 4. Thus, since the increase of the surface staining on the carrier 1 is detected by the sensor 16 and the stirring time of the developer is prolonged at an idling operation time and the like, the toner can be sufficiently electrified and the surface staining is prevented from occurring. |
