| 摘要 |
PURPOSE:To obtain excellent cleaning performance on the whole even if paper sizes are changed by dividing a recovery roller axially and electrically almost to each size of transfer paper and applying mutually different voltages. CONSTITUTION:The recovery roller 11 is divided into parts 21a-21c, whose boundaries are insulated electrically; and the divided areas are applied with voltages according to respective sizes of transfer paper. Contactors 22a-22c are contactors for supplying the respective voltages and a controller 16 generates signals for the respective sizes to set the voltages of the respective parts to desired values. For example, when a copy of A4 size is taken, the parts 21a and 21b are held at the same voltage as a voltage applied to a brush sleeve 10 and when a copy of B4 size is taken, the part 21a is held at the same voltage with the sleeve. Consequently, an abnormal decrease in toner density is eliminated and the polarity inversion of toner is stopped.
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