Patent ID: 7970299

Claim:
An image forming apparatus having a fusion unit so as to fuse developer deposited on a medium, comprising: a rotating body rotating in a feeding direction of said medium; a heating source heating said rotating body; a thermal unit for receiving radiated heat from said rotating body, disposed with a prescribed gap from said rotating body; a first temperature detection unit for detecting a value of the temperature of said thermal unit; a first holding unit for holding said thermal unit and said first temperature detection unit, the first holding unit having a first surface facing the rotating body and a second surface opposite to the first surface; a second temperature detection unit for detecting a value of the temperature of said first holding unit; a second holding unit for holding said second temperature detection unit, the second holding unit being disposed on the second surface of the first holding unit; a storage unit storing a previously calculated rotation time correction value and a previously calculated stopped time correction value; and a temperature calculation unit for correcting the value of the temperature of said thermal unit detected by said first temperature detection unit based on the value of the temperature of said first holding unit detected by said second temperature detection unit and based on the rotation time correction value or the stopped time correction value and for calculating a surface temperature of said rotating body, wherein the stopped time correction value is different from the rotation time correction value, wherein the rotation time correction value is used for a period where the rotating body is rotating, such that, when the rotating body is rotating, the temperature calculation unit calculates the surface temperature of the rotating body according to the value of the temperature of said thermal unit, the value of the temperature of said first holding unit and the rotation time correction value, and wherein the stopped time correction value is used for a period where the rotating body is stopped, such that, when the rotating body is stopped, the temperature calculation unit calculates the surface temperature of the rotating body according to the value of the temperature of said thermal unit, the value of the temperature of said first holding unit and the stopped time correction value.