A fusing device includes: an endless rotatable fusing belt; a nip forming member that is disposed on an inner circumferential surface of the fusing belt; a pressure roller that is in pressure contact with the nip forming member from an outer side of the fusing belt and forms a fusing nip area between the pressure roller and the fusing belt; and a heat source that is disposed inside the fusing belt and heats the fusing belt. The fusing device further includes a heat-conductive member that is disposed on a lateral side of an outer circumference of the fusing belt. The heat-conductive member extends over a width area in a rotation axis direction of the fusing belt.

An image forming apparatus includes a toner image forming unit, a fuser including a heater, a temperature sensor that detects a temperature of the fuser, and a controller. The controller exercises a standby control that includes repeating a control cycle, measuring a temperature fluctuation period that is a time period from start of energizing the heater to an end of the control cycle, and setting an energization amount for a next control cycle, based on the measured temperature fluctuation period. The control cycle includes energizing the heater with an energization amount during a preset heating period when the detection temperature has dropped to a temperature below the target standby temperature, and waiting until the detection temperature drops to the target standby temperature in a case where the detection temperature has risen to a temperature equal to or above the target standby temperature after the preset heating period has elapsed.

An image forming apparatus includes a heating rotary member that heats toner born on a recording material, and a pressure rotary member that pressurizes the heating rotary member. These rotary members form a fixing nip portion and fix a toner image to the recording material at the fixing nip portion while nipping and conveying the recording material. The apparatus further includes a web that collects toner adhering to a surface of the heating rotary member, a winding roller that winds the web, a motor that rotates the winding roller, a contact member that makes contact with an outer surface of the wound web and moves based on a position of the outer surface, a variable resistor that is connected to change a resistance value depending on a position of the contact member, and a control unit that controls a rotation amount of the motor based on the resistance value.

A fixing belt and a fixing device suppress charging of the fixing belt and permit securing of a withstand voltage of secondary parts of the fixing belt are provided in addition to a heater. The fixing belt is formed of a tubular endless fixing film including, in order from an inner peripheral side of the film, abase layer, an elastic layer, and a release layer. A surface resistivity of the fixing belt measured from the base layer side is 7 [LOG Ω/sq.] or more and 10 [LOG Ω/sq.] or less.

An image heating apparatus includes a first rotating member, a second rotating member to form a nip portion which sandwiches a recording material between the first rotating member and the second rotating member, a heater unit provided inside the first rotating member and having a heater for heating an image on the recording material sandwiched by the nip portion, and a sheet member provided to overlap a part of the heater and electrically connected to the heater. The sheet member includes a first sheet member connected to one end of the heater in a longitudinal direction of the heater and a second sheet member connected to the other end of the heater, the first sheet member extends from the one end of the heater in a direction crossing the longitudinal direction, and the second sheet member extends from the other end of the heater in the longitudinal direction.

A fixing device includes a fixing rotator over which a recording medium bearing an image is conveyed. A first heater heats the fixing rotator and generates heat evenly in a maximum conveyance span where the recording medium having a maximum width in a width direction of the recording medium is conveyed. The maximum width is available for the fixing rotator. A second heater heats the fixing rotator and generates heat in the maximum conveyance span. The second heater includes a first portion that generates heat in a first heat generation amount and a second portion that generates heat in a second heat generation amount that is greater than the first heat generation amount of the first portion.

A rotator driver includes an endless rotator having an end face in a longitudinal direction thereof. A slide aid contacts an inner circumferential face of the endless rotator. A lubricant is applied between the slide aid and the inner circumferential face of the endless rotator. An end face contact member contacts the end face of the endless rotator and has an end face opposed face contacting the end face of the endless rotator and an opposite face being opposite to the end face opposed face. A helical gear is mounted on the opposite face of the end face contact member. The helical gear has teeth being oriented to generate a force that moves the end face contact member toward the end face of the endless rotator as the helical gear rotates. The helical gear has an outer diameter being not greater than an outer diameter of the endless rotator.

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 heating device includes a heating roller having a resistance heat-generating layer that generates heat by passage of a current through the resistance heat-generating layer, a support member that supports a treatment portion in which a heating treatment is performed, a belt that is stretched between at least the heating roller and the support member and that rotates, and a pressure rotating body that rotates in such a manner as to press a sheet-shaped heating target that is an object to be subjected to a heating treatment against the treatment portion including an outer peripheral surface portion of the belt that is supported by the support member and in such a manner as to cause the heating target to pass through the treatment portion. The heating roller is not equipped with a power receiving component configured to receive a rotational power that is transmitted.

A fixing device includes a fixing rotating member, a heater, a fixing pad, a pressurizing member, a lubricant, and a surface layer. The fixing rotating member is configured to fix a toner image on a recording medium and is heated by the heater. The fixing pad is positioned on an inner circumferential side of the fixing rotating member, and presses the fixing rotating member from the inner circumferential side. The pressurizing member faces an outer circumferential surface of the fixing rotating member, and forms a nip for fixing between the pressurizing member and the fixing rotating member. The lubricant is applied to the fixing rotating member. The surface layer is disposed in a vicinity of an end portion of a pressurizing surface of the fixing pad and returns the lubricant to a longitudinal central side of the pressurizing surface.