A fixing device including a heated endless belt, a first member, a second member, a pressure roller, a guide member, a sliding member, and a lubricant application member. The first member is a non-rotating body inside of the belt and together with the second member tensions the belt. The pressure roller is outside the belt and presses against the first member via the belt, thereby forming the fixing nip. The guide member is inside of the belt and has a guide surface that guides the belt in circulation and a recess opening into the guide surface. The sliding member is between the belt and the first member. The lubricant application member is fitted in the recess and applies lubricant to the belt. The guide surface has an arc shape that is interrupted by the recess in a cross section perpendicular to an axis of rotation of the pressure roller.

A heater includes an insulator substrate, a heat generating section in which a plurality of divided regions are formed in a longitudinal direction on a first surface of the insulator substrate, electrodes formed at both end portions of the heat generating section to correspond to the plurality of divided regions, and electric conductors connected to at least one of the electrodes and formed over a surface different from the first surface of the insulator substrate.

According to one embodiment, a fixing device includes a heating rotating body having an first arched portion so that a first circular arc is formed in a cross section configured to rotate to be pressed against a medium so as to heat toner on the medium and an auxiliary heat-generating member having a second arched portion so that a second circular arc is formed in the cross section, the second arched portion being smaller than the first arched portion, configured to be supported at one end by a support member so as to be movable inside the heating rotating body and configured to contact with the first arced portion of the heating rotating body, the contact portion between the first arched portion and the second arched portion being closer to the support member than a middle point of the second circular arc in the cross section.

There is provided a heater according to an embodiment including a heat generating unit configured to generate heat by electric conduction; and a plurality of electrodes configured to be respectively disposed at facing side edges of the heat generating unit so as to be electrically connected to the heat generating unit and at least one side of the side edges is formed by cutting out a part thereof.

A fuser has a heater, a heat roller, an endless belt, a pressure pad, and a slidable sheet. The pressure pad forms a nipping portion to nip the endless belt between the pressure pad and the heat roller. The slidable sheet is interposed between an inner circumferential surface of the endless belt and the pressure pad in the nipping portion. The slidable sheet includes a plurality of dents and a plurality of projections on a surface contacting the inner circumferential surface of the endless belt. The plurality of dents are arranged in a first part of the surface of the slidable sheet. The first part is located in a range corresponding to the nipping portion. The plurality of projections are arranged in a second part of the surface of the slidable sheet. The second part is located in a range corresponding to a portion different from the nipping portion.

An image heating apparatus includes a first rotatable member, a second rotatable member, a laser light irradiation portion, and a cleaning member. The cleaning member is provided in a position other than a position where laser light emitted from the laser light irradiation portion toward the nip is blocked.

An image forming apparatus includes an image forming portion that forms a toner image on a recording material, and a first rotatable member and a second rotatable member, which form a nip therebetween in which the toner image, formed on the recording material by the image forming portion, is heated. A belt unit includes an endless belt that externally heats the first rotatable member, and a supporting mechanism rotatably supporting the endless belt. A moving mechanism moves the belt unit so as to be movable between a contact position and a spaced position. In addition, a controller executes a process in which one of the belt unit with a new endless belt and a new belt unit with a new endless belt is moved to the contact position, and then, the new endless belt is rotated for a predetermined time by the first rotatable member.

An image fixing device includes a rotatable fixing belt; a pressing roller forming a nip for feeding a sheet; a nip forming member contacted to an inner surface of the fixing belt to sandwich the fixing belt between the pressing roller to form the nip; a heating roller stretching the fixing belt; a cooling fan, for cooling the fixing belt, provided opposed to the belt at a position downstream of the heating roller and upstream of the nip forming member in the rotational movement direction of the fixing belt; a temperature sensor, for detecting a temperature of the fixing belt, provided at the position downstream of the cooling fan and upstream of the nip; and a controller for controlling power supply to the heater on the basis of an output of the temperature sensor.

A fixing device includes a rotatable pressing roller, a fixing rotator to rotate in contact with the pressing roller, a nip formation pad, and a slide sheet disposed between the nip formation pad and the fixing rotator. The slide sheet includes a base material layer made of a woven fabric of spun yarn. In the base material layer, a distance between adjacent spun yarns is equal to or less than 0.4 times a width of the spun yarn in a cross-section of the slide sheet in a direction of slide movement of the fixing rotator, and, in a cross-section of the slide sheet in a longitudinal direction of the slide sheet and a direction perpendicular to the slide movement of the fixing rotator, a thickness of the spun yarn is equal to or greater than 0.2 times a width of the spun yarn.

A fixing device includes an endless belt. A heat supply part is disposed inside the belt, contacts an inner circumferential surface thereof, and supplies heat thereto. A pressure member contacts an outer circumferential surface of the belt to form a nip portion, and conveys a recording medium while nipping the recording medium together with the belt. The heat supply part includes a heater having a plurality of heating sections arranged in a widthwise direction of the belt, and a thermal diffusion member extending in the widthwise direction between the heater and the belt. One surface of the thermal diffusion member contacts the inner circumferential surface of the belt, and the other surface contacts the heating sections. A plate thickness t (mm) between the surfaces of the thermal diffusion member, and a thermal diffusivity D (mm.sup.2/s) of the thermal diffusion member satisfy the relationship: tD6.7.