| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which achieves high image quality without difference in image quality between front and rear surfaces of a paper by disposing image forming units corresponding to both surfaces of the paper and printing both surfaces by one-time paper passing not to decrease a printing speed and employing the same transfer system for both surfaces. Ž<P>SOLUTION: A freely rotatable polarity conversion counter roller 48 is used as a counter electrode facing a polarity conversion means 47. The polarity conversion counter roller 48 uses a metallic bearing so as to be freely rotatable and is brought into forcible contact with (bites into) a second image carrier belt 31 with a spring SP by a force of 5N/cm and employs such a configuration that it can be grounded through the metallic bearing 49. Since the polarity conversion counter roller 48 is forcibly brought into contact with the second image carrier belt 31, the polarity conversion counter roller 48 uses a steel material and is plated with Ni and has a surface roughness μ of ≤0.3 in consideration of damage and enhancement of adhesion of a rear surface of the second image carrier belt 31. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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