Safety device for a toner image fixing device

摘要

Energy saving of fixing unit having a low heat capacity by reducing a loss of heat transferring from a temperature sensing element to temperature sensing means and by improving response of the safety device. A heat-insulating member (15) is formed to cover a temperature fuse (14) being a temperature sensing element and a heat-conductive filler or heat-conductive elastic member is formed between the temperature fuse (14) and a sliding sheet (17). A temperature sensing means (3) having the temperature sensing element abuts on a fixing roller (1) through a sliding sheet (17) interposed therebetween. A contacting portion of the temperature sensing means with the heat-insulating member (15) and the filler or elastic member (16) has a curved contacting surface fitting a cylindrical surface of the fixing roller (1). The heat-insulating member (15) has a groove or a slit for engaging with a protrusion of the temperature sensing element to be secured to the heat-insulating member.