FIELD

Embodiments described herein relate generally to an image forming apparatus and a control method.

BACKGROUND

In recent years, an on-demand fixing method has been proposed as one technique for reducing power consumption in an image forming apparatus. In such an on-demand fixing method, a film is driven by a rotating member having an elastic layer, and a conveyed sheet and developer are heated by a heater through the film. For such a heater, a material having an electrical resistance that varies according to temperature may be used as a heating element. A specific example of such a material is a positive temperature coefficient (PTC) material. A PTC material has a positive temperature coefficient of resistance (PTCR), i.e., the electrical resistance of the material increases as the temperature increases. When a PTC element is used, if the temperature of the heater rises to some extent, it is not easy to raise the temperature further, and therefore energy savings and safety can be obtained. On the other hand, when a PTC element is used, if the temperature of the heater is low, the resistance value is low, and there is a possibility that more power than expected is consumed.

