| 摘要 |
PROBLEM TO BE SOLVED: To prevent the occurrence of electrification unevenness and the deterioration of electrifying performance due to transfer residual toner mixed in the magnetic brush of a magnetic brush electrifying device. SOLUTION: The magnetic brush is constituted by magnetically constraining magnetic particles on an electrifying sleeve surface including a magnet roller, and the magnetic brush is brought into contact with the surface of a photoreceptive drum 1, and voltage from an electrifying bias applying power source 2a is applied to an electrifying sleeve, so that the surface of the photoreceptive drum 1 is electrified. After the transfer residual toner is temporarily recovered by the magnetic brush of the magnetic brush electrifying device 2, it is discharged to the surface of the photoreceptive drum 1, so that it is recovered by a developing device 4. Defective electrification is caused when a discharging amount is small, and when it is contrarily large, the down-time of a device is increased. The discharging amount is detected by a concentration sensor 8, and discharging time is decided so that a next discharging amount is made proper in accordance with a result. |
