Belt unit, fixing device and image forming apparatus

摘要

A belt unit includes an endless belt member, a first roller provided on an inner circumferential surface side of the belt member, and a stretching member provided on the inner circumferential surface side of the belt member. The stretching member is configured to stretch the belt member. A circumferential length of the belt member at a center portion in a widthwise direction of the belt member is shorter than a circumferential length of the belt member at an end portion in the widthwise direction of the belt member.

主权项

1. A belt unit comprising:
an endless belt member having a substantially constant thickness, a circumferential length of the belt member at a center portion thereof in a widthwise direction of the belt member being shorter than a circumferential length of the belt member at an end portion thereof in the widthwise direction of the belt member; a first roller provided on an inner circumferential surface side of the belt member, the first roller having a crown shape such that an outer diameter of the first roller at a center portion thereof in an axial direction of the first roller is larger than an outer diameter of the first roller at an end portion thereof in the axial direction of the first roller; a stretching member provided on the inner circumferential surface side of the belt member, the stretching member being configured to stretch the belt member, and a biasing member that biases the stretching member in a direction in which the stretching member applies tension to the belt member.