Patent ID: 9217960
Filing Date: 2015-12-22
Classification: G03G

Abstract:
1. An image forming apparatus comprising: first and second image bearing members, each configured to bear a toner image; a belt unit detachably mountable to a main assembly of said image forming apparatus, wherein said belt unit includes an endless belt onto which the toner images are to be transferred from said first and second image bearing members, at an image forming position where image formation is to be effected, in a contact state with said first and second image bearing members and includes first and second rollers, provided at an inner peripheral surface side of the belt, configured to stretch the belt, the first roller including a transmission portion; a slackness forming unit, provided in the main assembly, configured to perform a first function of forming a belt slacking region, at least at a portion where the belt opposes said first and second image bearing members, by acting on said belt unit and configured to perform a second function of eliminating the belt slacking region, said slackness forming unit including a driving force transmitting member connected to the transmission portion to rotate the first roller by a force by which said belt unit is moved; and a guiding unit configured to guide, when said belt unit is inserted into the main assembly and is moved to the image forming position, said belt unit so that said slackness forming unit performs the first function in a state in which the belt is spaced from said first and second image bearing members and so that said slackness forming unit performs the second function in a state in which the belt slacking region contacts said first and second image bearing members.