Fixing device and image forming apparatus provided therewith

A fixing device comprising:

• a fixing belt that is endless and that is rotatable along a conveyance direction of a recording medium;
• a pressing member that is pressed against a fixing roller across the fixing belt under a predetermined pressure to form a fixing nip portion between the pressing member and the fixing belt;
• and
• a heating unit that heats the fixing belt,
• wherein
• the heating unit includes:
• a coil that extends along an axial direction along which a rotation axis of the fixing roller extends with respect to an axis of rotation of the fixing belt;
• a bobbin that is disposed between the coil and the fixing belt, the bobbin holding the coil;
• an arch core that covers the coil from outward in a radial direction orthogonal to the rotation axis of the fixing roller and extends in a circumferential direction about the rotation axis of the fixing roller, a plurality of the arch cores being arranged in a row along the axial direction;
• an arch core holder that holds the arch cores from outward in the radial direction;
• and
• a cover that covers the arch core holder from outward in the radial direction, the cover forming a gas flow passage between the cover and the arch core holder, the gas flow passage extending along the axial direction,
• the cover has a pair of first opening portions disposed in opposite end parts along the axial direction and a second opening portion disposed in a middle part along the axial direction,
• the pair of first opening portions and the second opening portion are arranged in a row along the axial direction on a same plane, and
• an airflow entering the flow passage through one of the first and the second opening portions circulates along the axial direction and is discharged through the other of the first and the second opening portions.