Temperature control of a fixing apparatus using an induction heating system

An image forming apparatus comprising:

• an image forming portion configured to form a toner image on a recording medium;
• a heat generating member configured to have a metal conductive layer;
• an opposite member configured to form a nip between the heat generating member;
• a contact and separation mechanism configured to contact and separate the heat generating member to and from the opposite member;
• an induction current generating coil disposed around the heat generating member;
• a drive source configured to rotate the heat generating member forwardly and reversely;
• a temperature sensor disposed downstream from the nip of the heat generating member and upstream from the induction current generating coil of the heat generating member at a time of forward rotation of the heat generating member;
• and
• a power controller configured to control a power of the induction current generating coil, and based on the direction of rotation of the heat generating member to apply a prescribed power to the induction current generating coil, the power controller applies a lower power to the induction current generating coil at the time of reverse rotation of the heat generating member compared with a power applied at the time of forward rotation of the heat generating member.

A control method of a fixing apparatus, comprising:

• separating a heat generating member and an opposite member;
• heating the heat generating member;
• detecting a temperature of the heat generating member at a position downstream from a nip and a position upstream from a heating position at a time of forward rotation of the heat generating member;
• and
• controlling a power to heat the heat generating member lower at the time of the reverse rotation of the heat generating member than a power to heat the heat generating member at the time of the forward rotation of the heat generating member based on a direction of rotation of the heat generating member.