According to an embodiment, a heating device includes a cylindrical belt, a heater, a press roller, and a holder. The heater is disposed on an inner surface of the belt. The press roller rotates and is configured to contact an outer surface of the belt at a position opposite the heater to form a nip. The end portions of the press roller project by a first amount in a radial direction more than the central portion of the press roller. A holder has a first surface supporting the heater to face the cylindrical belt. The holder has a second surface that is opposite of the first surface with a center portion projecting in a direction orthogonal to the first surface more than the end portions of the second surface by a second projection amount that is greater than the first projection amount.

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 apparatus includes a guide member that guides a rotating member. The guide member has a contact surface that restricts a position of the guide member with respect to a stay by coming into contact with a surface of the stay on the upstream side in a printing-material conveying direction. The contact surface is disposed, in a direction perpendicular to the printing-material conveying direction, in such a manner that a center is downstream from ends in the printing-material conveying direction.

A fuser includes a pressure pad forming a nip with a fuser belt between the pad and a fuser rotator. A pressure face in contact with the belt has profiles in planes normal to the axis of the rotator. The profiles each include a reference section, the first to come into contact with the rotator with the belt in between when the pad forms the nip, and a boundary section at a threshold distance from the reference section in the width direction of the nip. When the pad is apart from the nip due to removal of a force applied by a pusher unit, the boundary section is, relative to the reference section, more largely displaced in the opposite direction to that of the rotator in one of the profiles located at a larger distance from a center portion of the pad in the axial direction of the rotator.

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 semiconductive roller is provided, which includes a tubular main body having a multiplicity of concavities (2) provided in an outer peripheral surface (1) thereof in at least one of circumferentially overlapping relation and axially overlapping relation. The concavities are each gently concave toward a center thereof from an outer periphery thereof. A semiconductive roller production method is also provided, which includes the step of forming the concavities by a laser processing method.

A fixing device includes a first pressing member, a fixing belt, a second pressing member, a tensioning section on which the fixing belt is wound on an upstream side relative to the fixing nip in a rotation direction of the fixing belt and which is configured to impart tension to the fixing belt, and a control section configured to control the tensioning section such that the shape in an axial direction of the fixing belt is changed in accordance with a type of sheet which passes through the fixing nip.

A fixing device includes a fixing belt, a nip pad, a press roller, a driving portion, and a heat generation source. The fixing belt has an endless shape. The nip pad is located on an inner circumferential side of the fixing belt. The nip pad presses the fixing belt. The press roller presses the fixing belt along with the nip pad. The driving portion moves the press roller toward the nip pad. The heat generation source causes the fixing belt to generate heat. A control section controls an image forming section and the fixing device. The nip pad includes a protrusion. The protrusion protrudes toward an outer circumference of the fixing belt and a downstream side of the nip. The control section changes a movement amount of a protrusion to the press roller.

A fixing device includes a first rotary body, a second rotary body to contact the first rotary body, and a plain bearing that supports the first rotary body or the second rotary body. One rotary body of the first rotary body and the second rotary body has an outer diameter increasing, while the other rotary body has an outer diameter decreasing, in a curved line from an axial center portion to axial end portions of the first rotary body and the second rotary body at least between the first rotary body and the second rotary body. A recording medium passes between the first rotary body and the second rotary body with a circumferential component of a shear force generated between the first rotary body and the second rotary body by use of the plain bearing being in a range of from 15N to 25N.

A fixing device includes a heater, a heating roller, a pressure rotary member, and guide member. The heating roller has an outer circumferential surface, has a center and one and another ends in a rotational axis direction thereof, and is rotated while being heated. The pressure rotary member is in pressure contact with part of the outer circumferential surface of the heating roller extending in an axial direction of the heating roller so as to be rotated while forming a pressure contact portion which allows a recording medium bearing an unfixed image to be introduced thereinto and pass therethrough. The guide member guides a leading end of the recording medium toward part of the outer circumferential surface of the heating roller approaching the pressure contact portion. An outer diameter of the heating roller gradually reduces from the center toward the one and the other ends.