Temp. control method for fixing device of image forming appts. using electrostatic photographing process - involves correcting any error that occurs between actual temp. of recording medium heating device and detected temp. as result of time delay in detection by temp. detector

摘要

The method involves correcting a detected temperature, above all, correcting a delay in the detection by a temperature sensor, in accordance with a predetermined equation involving the rate of change of temperature with a view to determining the electric power to be supplied. Electric power is supplied to the heater by using a particular pattern, and, above all, the electric power is supplied in a sampling period to be set up for the purpose and additionally in specific units formed by dividing the sampling period into smaller segments. The method also involves performing sequential control by using a temperature discriminating method for the pressurising roller and, above all, by estimating the temperature of a pressurising roller not provided with any temperature detecting device on the basis of a natural temperature decline process in the heating device, the quantity of heat which the heating device is deprived of, the transport of the recording medium, and so forth, and applying an adequate quantity of electric power to the heater on the basis of such an estimate.