| 摘要 |
PURPOSE:To improve picture quality by controlling a bias voltage of the opposite polarity of electrostatic charging characteristics of toner which is impressed to the reverse surface of a recording material according to the electric resistance of recording paper, and preventing a decrease in the sticking force of toner to the recording paper when the recording paper is in a moisture absorbing state. CONSTITUTION:When a measurement signal is inputted at timing before the recording paper P is carried on a guide plate 10 to a fixing roller 12, a bias transformer 21 impresses a specific bias voltage to the guide plate 10. At this time, a current flows from the guide plate 10 to an electrode 20 through the recording paper P and is converted by a resistance 24 into a voltage, which is passed through a voltage converting circuit 23 to input an analog voltage corresponding to the resistance value of the recording paper P to a sample and hold circuit 22. When a transistor 26 impresses a bias ON signal at timing right before the recording paper P is conveyed to the roller 12, and then the transformer 21 impresses a bias voltage corresponding to the current I, obtained by measuring the resistance value of the recording paper P, to the guide plate 10. Thus, a decrease in the sticking force of toner to the recording paper is prevented to improve the picture quality. |
