Patent ID: 8611802

Claim:
A fixing device for thermally fixing a developing agent image to a sheet comprising: a tubular flexible member having an inner peripheral surface defining an internal space and an outer peripheral surface opposite to the inner peripheral surface, the tubular flexible member defining an axis extending in an axial direction; a nip member disposed within the internal space; a temperature sensor configured to detect a temperature of the nip member; a backup member configured to provide a nip region in cooperation with the nip member for nipping the tubular flexible member between the backup member and the nip member; and a restricting member configured to restrict the tubular flexible member from moving in the axial direction, the restricting member having a base section, an inner guide protruding inward from the base section in the axial direction for guiding the inner peripheral surface and an outer guide protruding inward from the base section in the axial direction for guiding the outer peripheral surface, the inner guide having a portion whose protruding end is positioned inward of a protruding end of the outer guide in the axial direction, wherein the sheet is fed in a sheet conveying direction; wherein the inner guide has a first upstream portion located upstream and a first downstream portion located downstream in the sheet conveying direction, the outer guide having a second upstream portion located upstream and a second downstream portion located downstream in the sheet conveying direction, the first upstream portion and the second upstream portion defining a distance therebetween larger than a distance defined between the first downstream portion and the second downstream portion; and wherein the temperature sensor is disposed between the first upstream portion and the second upstream portion.