| 摘要 |
PURPOSE:To prevent offset phenomena of electrostatic attraction by knowing by a counter a time point when the charging polarity of a fixing roller is inverted, and applying a bias voltage so that the charging polarity of a toner and the charging polarity of the fixing roller become the same after a power source has been turned on. CONSTITUTION:A conductive brush 3 contacts the surface of a fixing roller 1, by which a voltage applying means for applying voltage is constituted. This conductive brush 3 is connected to a common terminal of a switching circuit 4, a terminal A and a terminal B of the switching circuit 4 are connected to a bias generating circuit 5, and this switching circuit 4 is switched by an output of a counter 6. Whenever a copy sheet number count signal is inputted, the counter advances a counting value by one, and when its counting value reaches K, a switching signal is generated, and supplied to the switching circuit 4. This counter 6 is reset, when a power source is turned off. Also, to the switching circuit 4, an initial contact switching circuit 7 is connected, and in accordance with the charging polarity of a toner to be used, an initial connecting contact of the switching circuit 4 is set.
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