| 摘要 |
PROBLEM TO BE SOLVED: To prevent toner from being deposited on a discharge brush 55 provided to a conveying belt 51.SOLUTION: In calibration mode, a shutter member is opened to expose a sensor surface of a density sensor 54. A transfer roller 26 is applied with a voltage of negative polarity. A driven roller 53 is also applied with a voltage of negative polarity. In addition to a current path from first electrical wiring L11 to an earth path L14, a current path is formed from second electrical wiring L12 to an earth path L13 via the driven roller 53 and a discharge brush 55. The driven roller 53 facing the discharge brush 55 has negative polarity, so that the discharge brush 55 has positive polarity, the same as toner charging polarity. The toner on a conveying belt 51 is not deposited on the discharge brush. |
