Patent ID: 8509640

Claim:
An image forming apparatus for forming an image on a medium, comprising: a sheet supply portion having a pick-up portion for picking up and supplying the medium to a medium transportation path; a transportation portion for transporting the medium along the medium transportation path; an image forming unit for charging and exposing an image supporting member to form a static latent image, and for developing the static latent image to form a developer image; a transfer portion for transferring the developer image to the medium; a fixing member; a pressing member abutting against the fixing member; a first temperature detection unit; a second temperature detection unit; a heating member for heating the fixing member; a power control unit for controlling power supplied to the heating member; a drive unit for rotating the fixing member; and a control unit for controlling the first temperature detection unit and the second temperature detection unit when the control unit receives an image forming command, wherein said control unit is arranged to control the first temperature detection to detect a first temperature of the fixing member before the fixing member starts rotating, said control unit is arranged to control the second temperature detection to detect a second temperature of the pressing member before the pressing member starts rotating, said control unit is arranged to calculate a difference between the first temperature and the second temperature before the fixing member starts rotating, said control unit is arranged to calculate an estimated temperature of the fixing member estimated to reach after the fixing member starts rotating according to the difference before the fixing member starts rotating, and said control unit is arranged to determine before the fixing member rotates whether a warming up is performed according to the estimated temperature and a fixing enable temperature range so that the estimated temperature is maintained within the fixing enable temperature range.