Fuser for reproduction apparatus with minimized temperature droop

Abstract

A fuser, for a reproduction apparatus, having at least one heated fuser roller operating at a setpoint temperature to permanently fix a marking particle image to a receiver member, and a mechanism for controlling temperature droop in the at least one heated fuser roller. The temperature droop controlling mechanism includes an external heat source movable to a position in operative relation with the heated fuser roller and a nonoperative position remote from the heated fuser roller. A logic and control unit regulates heat input to the heated fuser roller, during an idle period, to raise the setpoint temperature for the heated fuser roller a preselected amount relative to the operating temperature set point. At the actuation of the reproduction apparatus job run start, the control unit regulates heat input to the heated fuser roller by the fuser roller heater and the external heat source to raise the fuser operating temperature setpoint a preselected amount relative to the idle temperature setpoint. After a preselected time, the control unit actuates a source of air pressure to direct air flow at the fuser roller for creating an intended thermal gradient in the heated fuser roller. Then at a preselected time later, the control unit enables the first receiver member of a reproduction job run to be transported into operative relation with the heated fuser roller, whereby there is substantially no temperature droop in the heated fuser roller. Further, the logic and control unit actuates the pressurized air source to maintains such air flow for a preselected time after the last receiver member in a reproduction job run has passed through the fuser, whereby overshoot of the fuser roller temperature is minimized.