A fixing device includes a fixing rotator, a pressure rotator, a pressure plate, a pressing force adjuster, an entrance guide, an exit guide, and a guide. The pressure rotator presses the fixing rotator to form a nip between the fixing rotator and the pressure rotator. The pressure plate rotates about a fulcrum to press the pressure rotator. The pressing force adjuster adjusts a pressing force of the pressure rotator. The entrance guide guides a recording medium entering the nip. The exit guide guides the recording medium ejected from the nip. The guide guides the pressure rotator in a direction inclined from a line connecting a rotation center of the fixing rotator and a rotation center of the pressure rotator toward downstream in a conveyance direction of the recording medium.

A heating device includes a heater, a rotator, and a pressure rotator. The heater includes resistive heat generators forming a heat generation area and has a separation area formed by the resistive heat generators. The pressure rotator includes a first region and a second region. The first region faces the heater in a range of 20 mm from a center position of the heat generation area toward an end thereof in the arrangement direction. The second region faces the heater in at least a part of a range of 30 mm from a center position of the separation area toward the center position of the heat generation area. An outer diameter of the pressure rotator increases from the center toward the end. The outer diameter of the second region increases at an increasing rate larger than an increasing rate of the outer diameter of the first region.

An image formation apparatus according to an embodiment includes a fixation device and a controller. The fixation device includes: a fixation member that includes a first region and a second region located closer to a center in a longitudinal direction of the fixation member than the first region; a pressurizing member that forms a nip portion between the fixation member and the pressurizing member; first and second heat generating portions that heat the first and second regions, respectively; a first sensor that detects a first temperature of one of the pressurizing member and the fixation member at a position corresponding to the first heat generating portion; and a second sensor that detects a second temperature of the one at a position corresponding to the second heat generating portion. The controller controls a drive speed of the pressurizing member or the fixation member based on the first and second temperatures.

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.

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 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.

The roller for use in a fixing device, includes a metal core, a first elastic layer formed on an outer side of the metal core, the first elastic layer having voids, and a second elastic layer formed on an outer side of the first elastic layer, the second elastic layer having a microhardness higher than a microhardness of the first elastic layer, in which an outer diameter of an end portion of the roller is larger than an outer diameter of a middle portion of the roller in a longitudinal direction of the roller, and in which the microhardness of the second elastic layer is 25 degrees or more and 50 degrees or less.

A fixing apparatus a tubular film, a nip forming member that contacts an inner surface of the film, and a roller that forms a nip portion together with the nip forming member via the film. The nip portion is an area where the film and the roller are in contact with each other and where a recording material is conveyed. The nip forming member has a protruding portion, protruding toward the roller and extending in a generatrix direction, that is provided on at least one of an upstream side and a downstream side in the nip in a conveying direction of the recording material. In the conveying direction of the recording material, an end portion of the protruding portion in the generatrix direction is arranged at a location different from a central portion of the protruding portion in the generatrix direction.

An image formation apparatus according to an embodiment may include a fixation device and a controller. The fixation device includes: a fixation member includes a first region and a second region located closer to a center in a longitudinal direction of the fixation member than the first region; a pressurizing member that forms a nip portion between the fixation member and the pressurizing member; first and second heat generating portions that heat the first and second regions, respectively; a first sensor that detects a first temperature of one of the pressurizing member and the fixation member at a position corresponding to the first region; and a second sensor that detects a second temperature of the one at a position corresponding to the second region. The controller controls a drive speed of the pressurizing member or the fixation member based on the first and second temperatures.

A heating device includes: a rotating body; a heating body as defined herein; and a contact mechanism, in a non-existence state where a material to be heated does not exist between the rotating body and the heating body after the material to be heated passes between the rotating body and the heating body, configured to cause the rotating body to be in contact with the heating body at a central portion of the rotating body in a rotation axis direction of the rotating body, so that an area of the rotating body in contact with the heating body is smaller at each of both end portions of the rotating body than at the central portion of the rotating body in the rotation axis direction, or configured to switch the rotating body between a first contact state and a second contact state as defined herein.