Patent ID: 8606161

Claim:
An image forming apparatus comprising: an image forming section for forming a toner image and transferring the toner image onto a sheet; a fixing unit including a heating member and a pressing member, and fixing the toner image onto the sheet while nipping and conveying the sheet between the heating member and the pressing member, the fixing unit further including: a coil arranged along an outer surface of the heating member and generating a magnetic field; a first core arranged opposite the heating member with respect to the coil and forming a magnetic path; a second core so fixed between the first core and the heating member with respect to a direction in which the coil generates the magnetic field, as to form the magnetic path together with the first core; a shielding member positioned outward of the second core and shielding the magnetism in the magnetic path; and a magnetism adjusting unit moving the shielding member outward of the second core to switch the position of the shielding member between a shielding position where the shielding member shields the pass of the magnetism and a retracted position where the shielding member permits the pass of the magnetism, wherein the shielding member includes a ring-shaped frame made of a nonmagnetic metallic material and a ring surface defined by the ring-shaped frame to face an outer periphery of the second core; and the magnetism adjusting unit adjusts the position of the ring surface relative to the outer periphery of the second core to switch the position of the shielding member between the shielding position and the retracted position.