Fixing Device and Image Forming Apparatus

An image forming apparatus, comprising:

• a fixing device that has an electromagnetic coil placed with a gap from a member to be heated, the member being made of a magnetic material;
• a switching device that supplies electronic power to the electromagnetic coil;
• a switching control unit that controls duty ratio of a switching operation for the switching device under a condition that a load voltage and a load current of the switching device are substantially zero when the switching device is turned on and/or off;
• a shield member capable of being placed between the electromagnetic coil and the member to be heated to shield the member to be heated against a magnetic flux from the electromagnetic coil;
• and
• a shield control unit that controls a shield amount of the shield member by moving either the shield member or both the electromagnetic coil and the member to be heated for changing a distance between the shield member and the electromagnetic coil and a distance between the shield member and the member to be heated.

A fixing device, comprising:

• an electromagnetic coil placed with a gap from a member to be heated, the member being made of a magnetic material;
• a magnetic core that conducts a magnetic flux from the electromagnetic coil to the member to be heated;
• a switching device that supplies electronic power to the electromagnetic coil;
• a switching control unit that controls duty ratio of a switching operation for the switching device under a condition that a load voltage and a load current of the switching device are substantially zero when the switching device is turned on and/or off;
• and
• a distance changing unit that changes either a distance between the electromagnetic coil and the magnetic core or a distance between the member to be heated and the electromagnetic coil and/or a distance between the member to be heated and the magnetic core by moving the electromagnetic coil and/or the magnetic core.

An image forming apparatus, comprising:

• a fixing device that has (a) an electromagnetic coil placed with a gap from a member to be heated, and (b) a magnetic core that conducts a magnetic flux from the electromagnetic coil to the member to be heated, the member being made of a magnetic material;
• a switching device that supplies electronic power to the electromagnetic coil;
• a switching control unit that controls duty ratio of a switching operation for the switching device under a condition that a load voltage and a load current of the switching device are substantially zero when the switching device is turned on and/or off;
• and
• a distance changing unit that changes either a distance between the electromagnetic coil and the magnetic core or a distance between the member to be heated and the electromagnetic coil and/or a distance between the member to be heated and the magnetic core by moving the electromagnetic coil and/or the magnetic core.