Fixing device, image forming apparatus

A fixing device comprising:

• a magnetic flux generating unit;
• a first rotary body configured to generate heat through action of magnetic flux generated by the magnetic flux generating unit;
• a second rotary body disposed parallel with respect to the first rotary body;
• a fixing belt extended on and extended between the first rotary body and the second rotary body, and is to be heated by the first rotary body;
• a temperature sensing portion disposed in an upstream side from the second rotary body in a rotation direction of the fixing belt, but in a downstream side from the first rotary body in the rotation direction of the fixing belt, and capable of sensing temperature of the fixing belt;
• and
• a control portion configured to:
• measure a time period during which heating has been stopped before a heating-start instruction for heating the fixing belt is inputted to the magnetic flux generating unit;
• determine, after heating of the fixing belt is started, abnormality of the fixing belt based on a change rate over time of temperature sensed using the temperature sensing portion;
• and
• delay, for a predetermined time period, a timing at which heating of the fixing belt is to be started through generation of magnetic flux by the magnetic flux generating unit based on the heating-start instruction, under a condition that the measured time period during which heating has been stopped is shorter than a configured time period determined in advance and a temperature sensed by the temperature sensing portion is equal to or higher than a predetermined temperature.