Fixing device for use in image forming apparatus

摘要

In a fixing device of an image forming apparatus including a heating roller and a temperature detecting device spaced apart from the roller, having a first sensor for detecting the surface temperature of the roller, and a second sensor for detecting the ambient temperature, the first sensor being placed at a first position in a casing having an opening through which the heat radiation of the roller is directly incident and the second sensor being enclosed by the casing and placed at a second position to which the heat radiation of the roller is not directly incident, the temperature is calculated on the basis of the outputs of the two sensors, and the opening is disposed so as not to enter a region between the vertical plane containing the central axis of the roller and a tangential plane to the circumferential surface of the roller parallel to the vertical plane.