Fixing device and image forming apparatus

摘要

A fixing device includes a fixing belt, a heating source and a fixing roller. The fixing belt has a sheet passing part and a non-sheet passing part. The fixing roller includes an elastic layer including first and second elastic parts. The first elastic part is provided on an inner diameter side of the sheet passing part. The second elastic part is provided on an inner diameter side of the non-sheet passing part. A gap is formed between a part of the elastic layer and the fixing belt in a state where the fixing belt is not heated. The part of the elastic layer is in close contact with the fixing belt in a state where the fixing belt is heated. The first elastic part includes a small-diameter part having a smaller external diameter than a part with a maximum external diameter of the second elastic part.

主权项

1. A fixing device comprising:
a fixing belt provided rotatably and including a sheet passing part through which a recording medium passes and a non-sheet passing part provided on an outer side of the sheet passing part in a rotation axis direction of the fixing belt; a heating source configured to heat the fixing belt to a fixing temperature at which a toner image is fixed on the recording medium; and a fixing roller inserted in the fixing belt and including an elastic layer having a higher linear expansion coefficient than a linear expansion coefficient of the fixing belt, wherein the elastic layer includes: a first elastic part provided on an inner diameter side of the sheet passing part; and a second elastic part provided on an outer side of the first elastic part in the rotation axis direction of the fixing belt and provided on an inner diameter side of the non-sheet passing part, a gap is formed between at least a part of the elastic layer and the fixing belt in a state where the fixing belt is not heated by the heating source, and at least the part of the elastic layer is in close contact with the fixing belt by thermal expansion in a state where the fixing belt is heated to the fixing temperature by the heating source, the first elastic part includes a small-diameter part having a smaller external diameter than a part with a maximum external diameter of the second elastic part.