Fixing device and image forming apparatus

An image forming apparatus comprising:

• an image forming device to form a toner image;
• and
• a fixing device disposed downstream from the image forming device in a recording medium conveyance direction to fix the toner image on a recording medium,
• the fixing device including:
• an endless belt that is flexible and formed into a loop, the endless belt being rotatable in a rotation direction;
• a pressure rotator disposed opposite an outer circumferential surface of the endless belt;
• a first radiant heater disposed inside the loop formed by the endless belt, the first radiant heater including a first heat generator to heat the endless belt;
• a second radiant heater disposed inside the loop formed by the endless belt, the second radiant heater including a second heat generator, disposed outboard from the first heat generator in an axial direction of the endless belt, to heat the endless belt;
• a nip formation pad, disposed inside the loop formed by the endless belt, to form a fixing nip between the endless belt and the pressure rotator,
• the nip formation pad including a nip-side face disposed opposite the endless belt, wherein the first radiant heater and the second radiant heater are disposed away from the nip formation pad;
• a contact heater mounted on at least one lateral end of the nip formation pad in a longitudinal direction of the nip formation pad,
• the contact heater including:
• a nip-side face disposed opposite the endless belt;
• and
• a third heat generator to heat at least one lateral end of the endless belt in the axial direction of the endless belt;
• a thermal conduction aid, covering the nip-side face of the nip formation pad and the nip-side face of the contact heater, to conduct heat applied to the endless belt in the axial direction of the endless belt,
• the thermal conduction aid including a heater-side face being disposed opposite the contact heater and covering at least the third heat generator of the contact heater;
• an interposer interposed between the thermal conduction aid and the contact heater, wherein the interposer includes:
• a nip-side face being disposed opposite the thermal conduction aid and having a shape that corresponds to the thermal conduction aid;
• and
• a heater-side face being disposed opposite the contact heater and having a shape that corresponds to the contact heater,
• wherein the heater-side face of the thermal conduction aid contacts the nip-side face of the interposer and includes:
• a curved portion being curved in cross-section;
• and
• a flat portion being flat in cross-section, and
• wherein the nip-side face of the interposer contacts the curved portion and the flat portion of the thermal conduction aid.