Image forming apparatus

摘要

An image forming apparatus includes an image bearing member; an endless belt; a first driver for driving the belt in contact to an inner surface of the belt; a second driver for driving the belt in contact to an outer surface of the belt; and a tension detector for detecting a state of tension of the belt. The tension detector includes: a movable device, contacted to the belt in a region downstream of the second driver and upstream of the first driver and in a region upstream of the second driver and downstream of the first driver with respect to a rotational direction of the belt, capable of moving its position depending on the tension of the belt in the two regions; a member-to-be-detected capable of changing its position in interrelation with the movement of the movable device; and a detecting device for detecting the member-to-be-detected.

主权项

1. An image forming apparatus comprising:
an image bearing member for bearing a toner image; a rotatable endless belt; a first driving member for rotationally driving said endless belt and in contact with an inner peripheral surface of said endless belt; a second driving member for rotationally driving said endless belt and in contact with an outer peripheral surface of said endless belt, wherein said second driving member is provided at a position where it does not oppose said first driving member via said endless belt; and a tension detecting unit for detecting a state of tension of said endless belt; wherein said tension detecting unit comprises: a movable device, in contact with said endless belt in a first region from downstream of said second driving member to upstream of said first driving member and in a second region from downstream of said first driving member to upstream of said second driving member with respect to a rotational direction of said endless belt, and capable of moving its position depending on the tension of said endless belt in the first and second regions; a member to be detected capable of changing its position in interrelation with the movement of said movable device; and a detecting device for detecting said member to be detected.