Patent ID: 7343125
Filing Date: 2008-03-11
Classification: G03G

Abstract:
1. An image forming apparatus comprising: a plurality of image bearing members for bearing toner images; an intermediate transfer belt to which the toner images on the image bearing members are transferred; contacting and separating means for causing the image bearing members to be in contact with and separated from the intermediate transfer belt; a first image forming mode where one of the plurality of image bearing members is in contact with the intermediate transfer belt and where toner images on the image bearing members are transferred to the intermediate transfer belt; a second image forming mode where the plurality of image bearing members are in contact with the intermediate transfer belt and where toner images on the image bearing members are superimposedly transferred to toner images on the intermediate transfer belt; switching means for causing the image bearing members to be into contact with and separated from the intermediate transfer belt to switch the image forming modes; and bias controlling means for controlling the bias of the intermediate transfer belt by rotating the intermediate transfer belt until the toner images on the image bearing members are transferred to the intermediate transfer belt after the image bearing members have been caused to be in contact with or separated from the intermediate transfer belt, wherein a duration when the intermediate transfer belt is rotated by the bias controlling means when the second image forming mode is changed to the first image forming mode is shorter than a duration when the intermediate transfer belt is rotated by the bias controlling means when the first image forming mode is changed to the second image forming mode.