Fixing device and image forming apparatus including this fixing device

摘要

A fixing device includes a heating member pressed by a pressing member to form a nip part, an excitation coil generating a magnetic flux induction-heating the heating member, a magnetic core and a magnetism shielding member. The magnetic core is located opposite to the heating member across the excitation coil and provides a magnetic path passing through the excitation coil and heating member. The magnetism shielding member partially shields the magnetic path and includes a rotatable belt member allowing the magnetic flux to pass through, and a magnetism shielding layer arranged on a surface of the belt member. In the magnetism shielding layer, gap parts extending in a width direction of the belt member are arranged along a circumference direction of the belt member. When the magnetism shielding member is located to shield the magnetic path, inner wall faces of the gap part are brought into contact with each other.

主权项

1. A fixing device comprising:
a pressing member; a heating member pressed into contact with the pressing member to form a nip part; an excitation coil for generating a magnetic flux and provide a magnetic flux induction-heat to the heating member; a magnetic core located at an opposite side from the heating member across the excitation coil and configured to provide a magnetic path passing through the excitation coil and heating member; and a magnetism shielding member arranged so as to shield a part of the magnetic path, and configured to include a flexible endless belt member driven to rotate and allowing the magnetic flux to pass through, and a non-magnetic metal magnetism shielding layer arranged at a predetermined area in a surface of the belt member, and further, configured so that, in the magnetism shielding layer, gap parts extending in a width direction of the belt member are arranged at equal intervals in a circumference direction of the belt member, each gap part having opposite inner wall faces extending in the width direction, wherein, in a situation of the magnetism shielding member located at a position in which the magnetic path is shielded, the belt member is bent toward a side of the magnetism shielding member and the opposite inner wall faces of at least one gap part of the magnetism shielding layer are at least partly brought into contact with each other, and a several number of magnetism shielding layers is configured to have the respective gap parts formed in different shapes from each other with respect to at least one of an inclined angle of the inner wall face of each gap part against the surface of the belt member and a width of each gap part in the circumference direction.