Patent ID: 8818225

Claim:
A temperature control method of calculating a temperature of a recording medium used in a thermal fixing device including a fixing member and a pressing member, the temperature control method comprising: performing first-stage calculations before a start of printing by: dividing a region of a nip section of the thermal fixing device including the fixing member, the recording medium, and the pressing member into plural discrete points that include discrete points in respective areas of each of the fixing member, the recording medium, and the pressing member, and calculating temperatures of the plural discrete points using difference method calculations; and performing second-stage calculations in real time during fixing to calculate a result of the temperature of the recording medium in a state where fixing is finished, wherein the result of the temperature of the recording medium in the state where fixing is finished is used to control obtaining a desired temperature of the recording medium in the state where fixing is finished, wherein the result of the temperature of the recording medium in the state where fixing is finished is calculated based on a calculation of heat transfer between the plural discrete points in the nip section without directly measuring an actual temperature of the recording medium in the state where fixing is finished.