HEATING APPARATUS HAVING AN OPEN-LOOP C0NFIGURATION FOR CONTROLLING TEMPERATURE

A heating apparatus measures the operation time and the inoperative time using an operation equation to switch the magnitude of the thermal supply of the heating apparatus in accordance with the calculated values. The heating apparatus includes a heater as a heating thermal supply, a heating chamber to be heated by the heater, a driving device for controlling the supply energies to the heater, a parameter operation device for calculating, in accordance with a given operation equation, the parameter corresponding to the supply energies to the heater, an output deciding device for comparing the parameter operation value obtained by the parameter operation device with the given target value to decide the output level of the heating thermal supply. The parameter operation value is increased in accordance with the given operation equation by the parameter operation device during the energization into the heater, and when the value has reached the given value, the output deciding means increases or cuts off the average power to the heater.