Patent ID: 8693934

Claim:
A fixing device comprising: a heating rotary body to rotate in a predetermined direction of rotation, including a heat generation layer; and an induction heater to generate a magnetic flux toward the heating rotary body, disposed opposite the heating rotary body, the induction heater including: a first side core disposed at one end of the induction heater in the direction of rotation of the heating rotary body and extending in an axial direction of the heating rotary body, the first side core including a planar face; a second side core disposed at another end of the induction heater in the direction of rotation of the heating rotary body and extending in the axial direction of the heating rotary body, the second side core including a planar face; a center core disposed between the first side core and the second side core in the direction of rotation of the heating rotary body; an exciting coil to generate the magnetic flux, wound around the center core; and a plurality of arch cores arranged in the axial direction of the heating rotary body, each of which including: a first vault edge face, having a curved cross-section when viewed along a line parallel to a rotation axis of the heating rotary body, disposed at one end of the arch core in the direction of rotation of the heating rotary body and contacting the planar face of the first side core; and a second vault edge face, having a curved cross-section when viewed along a line parallel to the rotation axis of the heating rotary body, disposed at another end of the arch core in the direction of rotation of the heating rotary body and contacting the planar face of the second side core.