| 摘要 |
The fixing device fixes toner to a paper by a nip between a heating roller and a press roller which are opposed to each other. An exciting coil is provided inside the heating roller. Temperature detection mechanisms are provided at least two positions on the outer circumferential surface of the heating roller, between the exciting coil and a metal layer of the heating roller, or on the inner circumference of the exciting coil. Two of the temperature detection mechanisms are respectively provided at a center part and an end part in the lengthwise direction of the heating roller, with a predetermined angle inserted therebetween on the circumference of the metal layer of the heating roller. A data table is provided to detect the temperature of a wire material forming the exciting coil, from an extent of a temperature increase while the exciting coil is electrically conducted or an extent of a temperature decrease after the electric conduction to the exciting coil is stopped. The temperature increase and the temperature decrease are detected by each of the temperature detection mechanisms. If either the temperature increase or the temperature decrease deviates from a definition value held in the data table, the current electrically conducted to the exciting coil is shut off.
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