Fixing device and image forming apparatus incorporating same

摘要

A fixing device includes a fixing rotary body inside which a heat generator is disposed and an exciting coil unit disposed opposite the heat generator via the fixing rotary body. A first moving mechanism is connected to one of the heat generator and the exciting coil unit to move the one of the heat generator and the exciting coil unit between a first position where the exciting coil unit is disposed away from the heat generator and a second position where the exciting coil unit is disposed closer to the heat generator. The exciting coil unit heats a first heat generation layer of the fixing rotary body at the first position, and heats both the first heat generation layer of the fixing rotary body and a second heat generation layer of the heat generator at the second position.

主权项

1. A fixing device comprising:
an endless belt-shaped fixing rotary body including a first heat generation layer; a pressing rotary body disposed opposite the fixing rotary body to form a nip therebetween through which a recording medium bearing a toner image passes; a heat generator disposed opposite the fixing rotary body and including a second heat generation layer to heat the fixing rotary body, and the second heat generation layer is configured to be heated above a curie temperature of the second heat generation layer; an exciting coil unit disposed opposite the heat generator via the fixing rotary body to generate a magnetic flux; and a first moving mechanism connected to one of the heat generator and the exciting coil unit to move the one of the heat generator and the exciting coil unit between a first position where the exciting coil unit is disposed away from the heat generator and a second position where the exciting coil unit is disposed closer to the heat generator, wherein the exciting coil unit generates the magnetic flux so that only the first heat generation layer of the fixing rotary body generates heat by the magnetic flux at the first position to heat the fixing rotary body, and generates the magnetic flux so that both the first heat generation layer of the fixing rotary body and the second heat generation layer of the heat generator generate heat by the magnetic flux at the second position to heat the fixing rotary body, and wherein the heat generator including the second heat generation layer contacts the fixing rotary body including the first heat generation layer.