A heating device includes a cylindrical film a heater disposed inside the cylindrical film on an inner surface of the cylindrical film. The heater has a plurality of heating elements that are spaced from each other at intervals along an axial direction. A heat transfer member contacts the heater. The heat transfer member is arranged such that, in a first region of the heater that includes just a single one of the heating elements, contact between the heater and heat transfer member is greater than in a second region of the heater that includes an interval between a pair of adjacent heating elements.

According to an embodiment, an image forming apparatus measures a temperature of a pressing member and controls heat generation of a heater such that the measured temperature approaches a control temperature. Further, the image forming apparatus sets, before starting image formation of one job including image formation, one candidate temperature of a plurality of predetermined candidate temperatures different from each other as the control temperature on the basis of the number of sheets to be used and a sheet size to be used in the image formation of the one job.

An image forming apparatus includes a first rotating member, a heater, a second rotating member, a detecting unit, a switching unit, a controlling unit, and a power source device. In a first period, a resultant current of first and third currents is supplied to a first heat generating element, and the resultant current in a unit cycle of a first period is a current at which a first current supplying timing and timings of a maximum and a minimum of the third current do not overlap with each other. In a second period, a resultant current of second and third currents is supplied to a second heat generating element, and the resultant current in a unit cycle of the second period is a current at which a second current supplying timing and the timings of the maximum and the minimum of the third current overlap with each other.

The heating apparatus including a plurality of heat generation members including first, second and third generation members, the second heat generation member and the third heat generation member having lengths in a longitudinal direction shorter than a length of the first heat generation member, the heating apparatus including first, second, third, and fourth contacts, and a first switching unit configured to bring an electric path between the second contact and the fourth contact into one of a connecting state and an open state.

An image heating device includes a heater having a plurality of heating elements that heat a plurality of heating regions and a control portion that controls the supply of electric power to the plurality of heating elements. The power supply is controlled so that a first average temperature, which is an average value of control target temperatures of heating regions included in a first region located closer to one end side than a central heating region in a direction orthogonal to a conveying direction of a recording material, and a second average temperature, which is an average value of control target temperatures of heating regions included in a second region located closer to the other end side than the central heating region, are within a predetermined temperature range.

According to one embodiment, a heating device includes a fixing belt configured to be rotated and a pressure roller configured to abut against the fixing belt and be driven to cause the fixing belt to rotate. A heater is configured to heat the fixing belt. A motor is configured to drive the pressure roller to rotate. A current sensor is configured to measure a driving current of the motor. A controller is configured to stop the heater based on the measured driving current.

An example fuser includes a flexible fixing belt, a back-up to form a fixing nip with the fixing belt, a heater substrate having a first surface on which a heating element pattern is located and a second surface opposite to the first surface, the heater substrate to heat the fixing belt at the fixing nip, and a heat conduction member having a plurality of heat conduction segments contacting the first surface of the heater substrate.

An image heating device heats up an image formed on a recording material, the device having: a heating member provided with a heater having a plurality of heating elements juxtaposed in a direction perpendicular to a conveyance direction of the recording material; a roller, such that the circumference of the roller increases from a central portion towards ends portions, in a direction perpendicular to the conveyance direction; and a control portion that controls individually the power supplied to the plurality of heating elements. The control portion sets a control target temperature, being set in order to supply power to a heating element corresponding to a non-sheet passing area, from among the plurality of heating elements, to be higher than a lowest control target temperature from among control target temperatures that are set in order to supply power to a heating element corresponding to a sheet passing area.

A fixing device includes a tubular body in a tubular shape that forms a nip with a pressurizing member. The heater, disposed inside the tubular body, faces a part of the tubular body in a circumferential direction. The heat equalizing member is disposed on an opposite side of a side where the heater faces the tubular body. The heat equalizing member transfers heat from a place having a high temperature to a place having a low temperature in a second direction along an axial direction of the tubular body. The heat conductive member, disposed between the heater and the heat equalizing member, can conduct the heat in each of the second direction and a first direction in which the heater and the heat equalizing member face each other. A side portion of the heat conductive member in the second direction is divided into three or more portions.

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.