Patent ID: 8090282

Claim:
A fusing apparatus comprising: a fuser roll and a pressure roll which define a nip therebetween for receiving print media with an image to be fused thereon; an internal heat source disposed in an interior of the fuser roll; an external heat source disposed exterior to the fuser roll for heating an outer surface of the fuser roll; a first temperature sensor which monitors a temperature of the fuser outer surface, the first temperature sensor communicating temperature measurements to a fuser controller; and a second temperature sensor which monitors a temperature of the fuser roll interior, the second temperature sensor communicating temperature measurements to the fuser controller, the fuser controller estimating a thermal gradient based on the measurements communicated by the first and second sensors; at least one of the internal heat source and the external heat source being controlled by the fuser controller during a print job to adjust the thermal gradient between the interior of the fuser roll and the outer surface of the fuser roll.