Patent ID: 8224219

Claim:
A fixing device comprising: a heat fixing member that is rotatably supported and is heated; and a pressure fixing member that is supported in a state in which the pressure fixing member is pressed against the heat fixing member, an unfixed image on a surface of a medium between the heat fixing member and the pressure fixing member being fixed thereby, the heat fixing member including: an elastically deformable base body that is a metal cylinder extending in a width direction of the medium, the width direction intersecting a transport direction of the medium; holding members disposed at both end portions in an axial direction of the base body, the holding member including: an insertion portion that is inserted inside the end portion of the base body and maintains contact with the base body all along its periphery to hold a cross-sectional shape of the end portion of the base body in the axial direction in a circular shape; and a received portion that is disposed at an outer end of the insertion portion, in the width direction of the medium, and formed integrally with the insertion portion, and that is thicker than the insertion portion, and a heat source member that extends in an axial direction of the cylindrical base body and is disposed such that the heat source member does not contact the base body, and when the heat fixing member is rotated and a portion of the heat fixing member reaches a fixing portion at which the heat fixing member fixes the unfixed image on the surface of the medium, the portion of the heat fixing member elastically deforms without it being necessary to provide a member that contacts an inner surface of the base body in the fixing portion from within, applies pressure to the medium, increases the size of a contact area with the medium and applies heat to the medium, and after the heat fixing member is further rotated and the portion of the heat fixing member has passed the fixing portion, the heat fixing member elastically recovers its original shape.