| 摘要 |
<P>PROBLEM TO BE SOLVED: To reliably discriminate breaking including cracking of a belt without an error detection. Ž<P>SOLUTION: Monitoring for breaking of an intermediate transfer belt 16 is carried out in two stages. A first stage is a determination based on variation of a primary transfer voltage in which constant current control is carried out. A photoreceptor 28 and primary transfer rolls 18Y, 18M, 18C, 18K repeat contact and separation in an unstable state. As a result, resistance between the photoreceptor 28 and the primary transfer rolls 18Y, 18M, 18C, 18K is greatly varied and amplitude of the primary transfer voltage is made great. Therefore, a predetermination is made for the possibility of breaking in the intermediate transfer belt 16 at the point when the amount of amplitude in the primary transfer voltage becomes greater than prescribed. Next, the second stage is a determination based on a detected value by density sensors 112. The density sensors 112 are provided on both end sections of the intermediate transfer belt 16 in the width direction and are used for detection of image density and toner concentration and also serves as a means for determination of existence of breaking in the intermediate transfer belt 16. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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