Fixing device and image forming apparatus

An image forming apparatus comprising:

• a printer configured to transfer a toner image onto a recording medium;
• and
• a fixing device configured to apply energy to fix toner onto the recording medium onto which the toner image is transferred, wherein
• the fixing device includes
• a circulating member for fixing toner and having an annular peripheral wall that is circularly movable,
• a pressure member facing an outer peripheral surface of the circulating member and forming a nip with the circulating member,
• a heater inside the circulating member and operable to heat the circulating member,
• a reflector inside the circulating member and operable to reflect radiant heat of the heater to the circulating member,
• a heat storage section provided integrally with the reflector or connected to the reflector, and
• a driver configured to cause the heat storage section to abut on or separate from an inner peripheral surface of the circulating member,
• wherein the driver includes a first temperature sensor provided in the circulating member and a second temperature sensor provided in the heat storage section, and the driver is configured to cause the heat storage section to abut on or separate from the inner peripheral surface of the circulating member according to a temperature difference between a detected temperature at the first temperature sensor and a detected temperature at the second temperature sensor.

A heat transfer belt assembly for transferring heat to a medium by conduction, the heat transfer belt comprising:

• a circular wall rotatable around a holding member, the circular wall having an inner surface and an outer surface;
• a heater operable to emit heat radiation onto the inner surface of the circular wall;
• a reflector partially embracing the heater to direct the emitted heat radiation onto the inner surface of the circular wall, the reflector held by the holding member and operable to move relative to the circular wall;
• a heat storage section provided integrally with the reflector or connected to the reflector such that the heat storage section is movable to abut the inner surface of the circular wall to transfer heat absorbed by the reflector from the heater;
• and
• a first sensor operable to measure a temperature of the heat storage section and a second sensor operable to measure a temperature of the inner surface of the circular wall,
• wherein the heat storage section is configured to be moved to abut on the inner surface of the circular wall when the temperature of the heat storage section is higher than the temperature of the inner surface by a predetermined amount, and
• wherein the heat storage section is configured to be moved away from the inner surface of the circular wall when the temperature of the heat storage section is lower than the temperature of the inner surface.