Patent ID: 7336405

Claim:
A thermal fixing device for fixing toner images onto recording sheets, the thermal fixing device comprising: a heat member; a pressing member disposed in pressing contact with the heat member; a temperature sensor that detects temperature of the heat member; a sheet judgment unit that judges a type of recording sheet being used; a fixing temperature setting unit that sets a fixing temperature required to melt toner on a recording sheet disposed between the heat member and the pressing member; and a control unit that performs a high-temperature heat-up control and a toner fixing control after the high-temperature heat-up control, wherein during the high-temperature heat-up control the control unit controls the heat member to heat up to a high fixing temperature that is higher than the fixing temperature set by the fixing temperature setting unit, wherein during the toner fixing control the control unit controls the heat member to the fixing temperature set by the fixing temperature setting unit, and wherein the control unit bypasses the high-temperature heat-up control to heat the heat member directly to the fixing temperature without going through a temperature that is higher than the fixing temperature to maintain the heat member to the fixing temperature when the sheet judgment unit judges a predetermined type of recording sheet.