| 摘要 |
PURPOSE:To obviate color mixing of toners even in long-period use by satisfying specific relations between the peak to peak voltage of the AC component of a bias voltage and the DC voltage of the DC component thereof as well as the potential of a 1st electrostatic latent image and the distance between a developer carrying body and image carrying body. CONSTITUTION:The bias voltage is applied between the developer carrying body 7a and image carrying body 1 of a 2nd developing device 7 so that the peak to peak voltage VP-P of the Ac component of the bias voltage, the DC voltage VDC of the DC component of the bias voltage, the potential VT of the 1st electrostatic latent image electrostatically charged by a charger 2 and the distance (d) between the body 7a and the body 1 satisfy the relation [VT-(VDC-VP-P/2)]/d<=2.25 when the potential of the electrostatic latent image is positive and satisfy the relation [(VDC+VP-P/2)-VT]/d<=2.25 when the potential of the electrostatic latent image is negative. Intrusion of the toner of the 1st toner image in the 2nd developing device is thereby obviated and the generation of the color mixing is prevented for a long-period of time when VT, VDC and VP-P satisfy the relations expressed by the above-mentioned equation.
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