Abstract: An image forming device includes: a fixing portion including a nip that is formed between a heat roller and a back-up roller pressurized by a pressurizing mechanism and holds and conveys a toner-bearing sheet; a pressure switching mechanism for changing a pressurizing force of the pressurizing mechanism; and a sheet detecting portion for detecting a sheet conveyed to the fixing portion. The sheet detecting portion changes a state of sheet detection by the sheet detecting portion in tandem to operation of the pressure switching mechanism. The image forming device includes a pressurization state determining portion for determining a state of pressurization of the pressurizing mechanism on the basis of an output of the sheet detecting portion for a sheet non-passing time, and a pressurization state display portion for displaying the pressurization state determined by the pressurization state determining portion.

Abstract: Provided is a fixing device including: a heater; a heating body that is heated by the heater and is caused to rotate; a pressure body that is in contact with the heating body, and is caused to rotate; a plurality of temperature sensor units each including a temperature sensing element that is covered with a protective member and is in contact with the heating body in order to sense a temperature of the heating body; and a control unit that recognizes temperatures of the heating body at respective portions thereof based on signals received from the temperature sensor units, brings the heater into an ON state if the recognized temperatures exhibit a temperature difference of a predetermined value or larger, judges that the protective member has peeled off if all the temperatures sensed by using the temperature sensor units are recognized to have risen, and corrects the temperature.

Abstract: An image forming device includes: a fixing portion including a nip that is formed between a heat roller and a back-up roller pressurized by a pressurizing mechanism and holds and conveys a toner-bearing sheet; a pressure switching mechanism for changing a pressurizing force of the pressurizing mechanism; and a sheet detecting portion for detecting a sheet conveyed to the fixing portion. The sheet detecting portion changes a state of sheet detection by the sheet detecting portion in tandem to operation of the pressure switching mechanism. The image forming device includes a pressurization state determining portion for determining a state of pressurization of the pressurizing mechanism on the basis of an output of the sheet detecting portion for a sheet non-passing time, and a pressurization state display portion for displaying the pressurization state determined by the pressurization state determining portion.