| 摘要 |
PROBLEM TO BE SOLVED: To provide a fixing device and an image forming apparatus, which enables appropriate detection of an anomaly in a heater, even if an inexpensive temperature detection unit, having stability, is used. SOLUTION: A center thermistor 41 is disposed on, in a contacting manner, the surface area of a heating roller 26 where the image forming areas Wa and Wb of a sheet 3 pass. Accordingly, in order to prevent deterioration in the temperature detection performance of a thermistor element 48 for detecting the temperature of the center thermistor 41, which would otherwise be caused when toner adheres to the thermistor element 48, the thermistor element 48 is coated with the leading end portion 46a of a metal plate 46 having a thickness of about 0.5 mm. Consequently, since the center thermistor 41 is protected by the leading end section 46b of the metal plate 46, the reaction speed of the thermistor element 48 is lower than the reaction speed of the thermistor element 58 of an end thermistor 51. When the center limit temperature T<SB>A</SB>is made equal to end-limit temperatures T<SB>B1</SB>and T<SB>B2</SB>, the actual temperature has exceeded the temperatures T<SB>B1</SB>and T<SB>B2</SB>, when the center thermistor 41 detects the temperatures T<SB>B1</SB>and T<SB>B2</SB>, which may lead to the possibility of the temperature reaching a fixing disabled temperature T. For this reason, the temperatures are set with T<SB>B1</SB>, T<SB>B2</SB>>T<SB>A</SB>. COPYRIGHT: (C)2007,JPO&INPIT |
