Heated fuser roll

Abstract

A heated fuser roll for use in a fuser apparatus for fixing toner images to a support surface is disclosed. The fuser roll includes a sleeve member having two heating units positioned within the member. Each heating unit includes a plurality of heating elements formed of a semiconducting ceramic material having a positive temperature coefficient of resistivity and exhibiting a Curie temperature transition point at which the resistance of the material increases with increasing temperature. The heating units are separated from each other by an insulating member. The fuser includes a thermally sensitive switch for controlling power to the heating elements when starting the fuser from a cold state. The switch is adapted to electrically connect the heating units in series when power is first applied to the fuser and then electrically connect the heating units in parallel when the heating elements are heated to the Curie temperature.

Dependencies are inferred from the claim text.