Patent ID: 8150289

Claim:
An image forming apparatus, comprising: an imaging section to form an image with toner on a recording sheet; and a thermal fixing device to fuse the toner image onto the recording sheet passing through a fixing nip, the fixing device including: a fixing member rotatable to convey the recording sheet during fixing, a pressure member pressed against the fixing member to form the fixing nip therebetween, a heater to heat at least a portion of the fixing member, a temperature sensor to sense a temperature of the fixing member, and a temperature controller to control the temperature of the fixing member in at least one of an on-off mode and a PID mode, wherein the heater only locally heats the fixing member during standby where the fixing member stops rotation, and uniformly heats the rotating fixing member to an operational temperature during recovery where the fixing member resumes rotation in preparation for fixing, wherein the temperature controller initially operates in the on-off mode upon entering recovery, and subsequently switches to the PID mode at a threshold time elapsing after entering recovery, and wherein the temperature controller determines the threshold time at least in part according to one or more of a duration of standby, a thickness of the recording sheet, a temperature of the pressure member, and a print mode of a print job executed by a printing section.