Fixing device and image forming apparatus incorporating same

A fixing device comprising:

• a fixing rotary body to rotate in a predetermined direction of rotation, including a first heat generation layer;
• a pressing rotary body disposed parallel to and pressed against the fixing rotary body to form a fixing nip therebetween through which a recording medium bearing a toner image is conveyed;
• a heat generator to heat the fixing rotary body to a predetermined target temperature, separably contacting the fixing rotary body and including a second heat generation layer;
• a first exciting coil to generate a magnetic flux, disposed opposite the heat generator via the fixing rotary body in a first region;
• a second exciting coil to generate a magnetic flux, disposed opposite the heat generator via the fixing rotary body in a second region sandwiching the first region in the direction of rotation of the fixing rotary body;
• an alternating electric current power supply connectable to the first exciting coil and the second exciting coil;
• and
• a switch circuit connected to the first exciting coil, the second exciting coil, and the alternating electric current power supply to selectively connect the alternating electric current power supply to the first exciting coil and the second exciting coil,
• wherein when the switch circuit connects the alternating electric current power supply to both the first exciting coil and the second exciting coil, the first exciting coil and the second exciting coil together generate a first magnetic flux having a first density that reaches only the first heat generation layer of the fixing rotary body, and
• wherein when the switch circuit connects the alternating electric current power supply to the first exciting coil only, the first exciting coil generates a second magnetic flux having a second density greater than the first density that reaches both the first heat generation layer of the fixing rotary body and the second heat generation layer of the heat generator.