| CPC G03G 15/2053 (2013.01) [G03G 15/2017 (2013.01); G03G 15/2064 (2013.01)] | 11 Claims |
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1. A fixing unit comprising:
a tubular film;
a nip forming member including a surface configured to be in sliding contact with an inner surface of the film;
a magnetic body inserted to an inner space of the film and that extends in a longitudinal direction of the film;
a coil wound around the magnetic body, formed in a helical shape along the longitudinal direction, and inserted to the inner space of the film with the magnetic body; and
a pressing roller that is configured to be in contact with an outer surface of the film, and that is arranged to sandwich the film together with the nip forming member to form a nip portion between the film and the pressing roller,
wherein the film includes a conductive layer configured to generate heat in a case where an alternating current is supplied to the coil and an electric current is induced in a circumferential direction of the film by principle of induction heating, an inner layer formed on an inner circumference side of the conductive layer, and an outer layer formed on an outer circumference side of the conductive layer,
wherein, in a case where the longitudinal direction is referred to as a first direction, a recording material conveyance direction at the nip portion is referred to as a second direction, and a direction orthogonal to both the first direction and the second direction is referred to as a third direction, the surface of the nip forming member includes a protruded portion that is protruded toward the pressing roller in the third direction, and the surface of the nip forming member is formed such that a curvature of the film when viewed in the first direction is maximum at a contact portion between the film and the protruded portion,
wherein as seen in the first direction, a neutral axis of the film is positioned within the outer layer, and
wherein the outer layer is formed of an insulator.
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