Provided is an image heating apparatus including: a heater having a plurality of heating elements arranged in a direction orthogonal to a conveying direction of the recording material; and a control portion that controls electric power to be supplied to the plurality of heating elements and is capable of individually controlling the plurality of heating elements, the image heating apparatus heating an image formed on the recording material with heat by the heater, wherein the control portion sets a heating condition when controlling each of the plurality of heating elements, according to the thermal history of a heating region heated by one heating element and the thermal history of a heating region heated by a heating element adjacent to the one heating element.

A heater includes: a substrate including metal and having a shape extending in one direction; a first insulating part provided on a first surface of the substrate; a first heating element provided on the first insulating part and extending along a longitudinal direction of the substrate; a first protection part provided on the first insulating part and covering the first heating element; a second insulating part provided on a second surface of the substrate facing the first surface; a second heating element provided on the second insulating part and extending along the longitudinal direction of the substrate; and a second protection part provided on the second insulating part and covering the second heating element. A length of the second heating element is different from a length of the first heating element in the longitudinal direction of the substrate.

A nip forming device includes an endless belt that is flexible and rotates and a nip former that is disposed opposite an inner circumferential face of the endless belt. A pressure rotator presses against the nip former via the endless belt to form a nip between the endless belt and the pressure rotator, through which a conveyed object is conveyed. A separator is disposed downstream from the nip in a conveyance direction of the conveyed object. The separator separates the conveyed object from the endless belt. The separator includes a non-contact portion separated from the endless belt and a contact portion that contacts the endless belt. The contact portion retains a gap having a predetermined size between the non-contact portion and the endless belt.

A heating device according to an embodiment generally includes heat generating parts and temperature sensors. The heat generating parts are divided into a plurality of blocks, so that the plurality of heat generating parts are arranged with a gap therebetween on a substrate in each block. With a temperature detection region provided in each block, the temperature sensors are provided corresponding to the heat generating parts with the gaps being avoided. The temperatures of the heat generating parts are detected by the temperature sensors that are less in number than the plurality of heat generating parts.

According to one embodiment, a heating apparatus includes a belt having a width along a first direction and a resistive heating body having a first side facing the belt and a second side opposite the first side. The resistive heating body includes a plurality of power terminals spaced along the first direction. The resistive heating body is configured to generate heat when power is applied to a pair of power terminals from the plurality of power terminals. An adjustment section of the heating apparatus is configured to selectively apply power to different pairs of power terminals in the plurality of power terminals to change a heating range of the resistive heating body along the first direction.

An image forming apparatus includes a photoconductive drum, a developing roller, a sheet supplier, a fixing unit, and a controller. The fixing unit includes a heating roller, a first heater, a second heater, a first temperature sensor, and a second temperature sensor. The controller is configured to control the first heater so that a first detected-temperature becomes a target temperature at a central area, and control the second heater so that a second detected-temperature becomes a target temperature at an end area, and in accordance with a heat storage amount of the fixing unit stored by the heating of the second heater, change (i) a timing when supply of the sheet is started or (ii) the target temperature at the end area.

According to one embodiment, a fixing device includes a belt, a heater, and a holder. The holder has a plurality of support portions that contact an end of the first heating region and an end of the second heating region along the direction perpendicular to the transport direction, and a plurality of non-contacting portions that do not contact the end of the first heating region and the end of the second heating region between the plurality of support portions, the end of the second heating region contacts one of the plurality of support portions at a side in the direction perpendicular to the transport direction, and the end of the second heating region faces to one of the plurality of non-contacting portions at the other side in the direction perpendicular to the transport direction.

An image forming apparatus includes an image forming device that forms images in an image region on a sheet. An image fixing device includes heater elements disposed along a sheet-width direction. A controller is configured to identify a heater element that will overlap with an edge of the image region when a sheet is conveyed to the image fixing device. The controller calculates whether a shift of the image region by a shift amount less than a threshold would cause the heater element to not overlap. If so, the image forming device is controlled to form the image in a shifted image region and only those heater elements in the plurality of heater elements that overlap with the shifted image region are turned on when fixing the sheet if the image has been formed in the shifted image region.

A fixing device includes a nip formation pad that presses against a pressure rotator via an endless belt to form a fixing nip between the belt and the pressure rotator, through which a recording medium bearing a toner image is conveyed. A fixing heater is disposed opposite at least a center span of a conveyance span of the belt in an axial direction thereof where the recording medium is conveyed to heat the belt. A first lateral end heater and a second lateral end heater are mounted on the nip formation pad and disposed opposite a first lateral end span and a second lateral end span of an inner circumferential surface of the belt in the axial direction thereof, respectively, to heat the belt. The second lateral end heater is electrically connected in series to the first lateral end heater.

A heater of the present invention includes jointed heat generating resistors having a positive temperature characteristic of resistance and provided between a first conductive element and a second conductive element on a substrate in a longitudinal direction of the substrate, and a plurality of heating blocks provided in the longitudinal direction, each of which is a set of the first conductive element, the second conductive element, and the heat generating resistor, and power supplied to at least one of the plurality of heating blocks can be controlled independent of other heating blocks.