Fixing apparatus and image forming apparatus

A fixing apparatus configured to heat a toner image on a recording material and fix the toner image to the recording material, the fixing apparatus comprising:

• a rotary member that is cylindrical and is configured to come into contact with the recording material, including a heat-generation layer being conductive and comprising a plurality of rings each continuous in a circumferential direction of the rotary member, the plurality of rings being electrically separated from one another in a rotation axis direction of the rotary member;
• a magnetic field generator disposed on an inner circumferential side of the rotary member and configured to, by being supplied an alternating current, generate an alternating magnetic field to induce a circulating current flowing in the circumferential direction in each of the plurality of rings of the heat-generation layer;
• a temperature detecting portion configured to detect a temperature of the rotary member;
• a conduction detecting unit configured to detect a conduction failure in an opposing ring that is one of the plurality of rings of the heat-generation layer and that opposes the temperature detecting portion;
• and
• a controller configured to control supply and interruption of power to the magnetic field generator on a basis of detection results of the temperature detecting portion and the conduction detecting unit,
• wherein the conduction detecting unit includes:
• a first magnetic core disposed on an outer circumferential side of the rotary member;
• a second magnetic core disposed on the inner circumferential side of the rotary member and configured to form, together with the first magnetic core, a magnetic path surrounding the circulating current flowing in the opposing ring;
• and
• a current detecting portion including a detection coil wound around one of the first magnetic core and the second magnetic core and configured to output a signal corresponding to the circulating current flowing in the opposing ring, and
• wherein a length in the rotation axis direction of the one of the first magnetic core and the second magnetic core around which the detection coil is wound is less than a length in the rotation axis direction of another of the first magnetic core and the second magnetic core around which the detection coil is not wound.