Patent ID: 8103189
Filing Date: 2012-01-24
Classification: G03G

Abstract:
1. An image forming apparatus, comprising: an image bearing member configured to bear a toner image; a main body having an apparatus body frame; a plurality of positioning portions disposed at the apparatus body frame; a belt unit removable from the main body and configured to be engaged with the plurality of positioning portions so as to be positioned in the main body, the belt unit including an endless belt configured to transfer the toner image from the image bearing member onto a recording material, first and second stretching members configured to stretch an inner face of the belt, a third stretching member configured to stretch the inner surface of the belt so as to apply tension to the belt, and a plurality of belt frames, the plurality of belt frames each including at least a first belt frame configured to hold the first stretching member and a second belt frame configured to hold the second stretching member at least one end of the endless belt in a longitudinal direction; and a pressure removing member configured to move the third stretching member from a first position to apply the tension to the belt to a second position to remove the tension from the belt, wherein, on a same end surface of the endless belt in the longitudinal direction, the first belt frame and the second belt frame are movable independently from each other, the first belt frame includes a first holding portion configured to hold the first stretching member, the second belt frame includes a second holding portion configured to hold the second stretching member, and the first holding portion and the second holding portion are capable of being engaged with the positioning portion independently from each other, and wherein the first holding portion and the second holding portion are engaged with the positioning portion independently from each other in a state in which the pressure removing member restricts the third stretching member to the second position so that the belt unit is positioned in relation to the apparatus body frame, and the pressure removing member moves the third stretching member from the second position to the first position so that the third stretching member applies a tension to the belt.