Fixing device using an induction heating unit

A fixing device comprising:

• a first roller that is made of a conductive material, and driven to be rotated;
• a second roller that is in contact with the first roller to pass a fixing medium on which a developer image formed between these rollers;
• an induction heating unit that is arranged at the first roller side and concentrates the induction heating to a nip portion of the first roller to change the developer image formed on the fixing medium to a fixed image;
• a first controller to control the first roller to be rotated at the time of warm-up and at the time of ready similarly at the time of executing the fixing and differentiates its rotating speed at the time of warm-up and ready and at the time of executing the fixing;
• and
• a second controller to control the induction heating unit to vary the operating current thereof from the normal current level when the rotating speed of the first roller is reduced;
• wherein the first controller decreases the rotating speed of the first roller at the time of warm-up and ready to a speed lower than that at the time of executing the fixing.

A fixing device comprising:

• a heating member that moves at a speed equal to a moving speed of a fixing medium and by contacting the fixing medium, fixes an image on the fixing medium by heating it;
• and
• an induction heating unit to heat the heating member;
• wherein the induction heating unit has a core element and a coil element wound round the core element and the core element is divided into plural portions on a surface inclined at a specified angle against a surface that is vertical to the surface of a fixing medium and parallel to a conveying direction of the fixing medium, the divided plural portions of the core element are bonded by bonding agent into one united body.

A fixing device comprising:

• a heating member that moves at a speed equal to a moving speed of a fixing medium and by contacting the fixing medium, fixes an image on the fixing medium by heating it;
• and
• an induction heating unit to heat the heating member;
• wherein the induction heating unit has a core element and a coil element wound round the core element, and the core element is divided into plural portions on the dividing surfaces that have a surface vertical to a conveying direction of the fixing medium, the divided plural portions of the core element are bonded by a bonding agent into one united body.

A fixing device comprising:

• a heating member that moves at a speed equal to the moving speed of a fixing medium and by contacting the fixing medium, fixes an image on the fixing medium by heating it;
• and
• an induction heating unit to heat the heating member;
• wherein the induction heating unit has a core element and a coil element wound round this core element and the heating member is made by combining a magnetic material and a high heat permeable material by the fusing and forging.