A fixing device includes a cylindrical heat roller, a heating element, a pressure roller, and an auxiliary roller. The heating element is provided inside the heat roller and configured to apply heat to the heat roller. The pressure roller is configured to be pressed against the heat roller to form, with the heat roller, a nip area where a recording paper sheet is to be nipped. The auxiliary roller is provided inside the heat roller and configured to be pressed toward the pressure roller with a peripheral wall of the heat roller in between. An outer peripheral surface of the auxiliary roller pressed against an inner peripheral surface of the heat roller is formed into an inverted crown shape so that an outside diameter of the auxiliary roller gradually decreases from both axial ends of the auxiliary roller toward an axial center thereof.

A fusing device includes a driving roller and a fusing unit. The driving roller is for driving a printing media to move. The fusing unit includes a heat insulating component, a heating component, a heat conductive component, a heat reflecting component and a fusing component. The heating component is for generating heat. The heat reflecting component includes a reflecting portion having a cross section formed in a conic section substantially. The reflecting portion is located at a side of the heating component away from the heat conductive component for reflecting the heat generated from the heating component to the heat conductive component. The heat conductive component transfers the heat to the fusing component. The fusing component contacts with the printing media to fuse toners onto the printing media when the driving roller drives the printing media to move.

A fusing device includes a driving roller and a fusing unit. The driving roller is for driving a printing media to move. The fusing unit includes a heat insulating component, a heating component, a heat conductive component, a heat reflecting component and a fusing component. The heating component is for generating heat. The heat reflecting component includes a reflecting portion having a cross section formed in a conic section substantially. The reflecting portion is located at a side of the heating component away from the heat conductive component for reflecting the heat generated from the heating component to the heat conductive component. The heat conductive component transfers the heat to the fusing component. The fusing component contacts with the printing media to fuse toners onto the printing media when the driving roller drives the printing media to move.

A fixing device includes a rotatable cylindrical heating roller, a heat source and a pressing roller. The heat source is arranged in a hollow inner space of the heating roller. The pressing roller is pressed against the heating roller to form a fixing nip through which a sheet is passed in a sheet passing direction. The heating roller has a substrate layer and a heat conductive layer. The substrate layer is formed such that both end portions in a width direction perpendicular to the sheet passing direction are made thinner than a center portion in the width direction, within a sheet passing area through which the sheet is passed. The heat conductive layer is provided around an outer circumferential face of the substrate layer and has a heat conductivity higher than the substrate layer.

A fixing device includes a rotatable cylindrical heating roller, a heat source and a pressing roller. The heat source is arranged in a hollow inner space of the heating roller. The pressing roller is pressed against the heating roller to form a fixing nip through which a sheet is passed in a sheet passing direction. The heating roller has a substrate layer and a heat conductive layer. The substrate layer is formed such that both end portions in a width direction perpendicular to the sheet passing direction are made thinner than a center portion in the width direction, within a sheet passing area through which the sheet is passed. The heat conductive layer is provided around an outer circumferential face of the substrate layer and has a heat conductivity higher than the substrate layer.