Abstract: A fusing device for an image forming apparatus that heats an infused image on a printing medium by an electromagnetic induction heating method includes a heated member having a metallic layer; a plurality of main cores disposed to be spaced apart a predetermined distance from a surface of the heated member, the plurality of main cores arranged to be spaced apart a predetermined interval from each other in a length direction of the heated member; and a main coil wound to surround the plurality of main cores.

Abstract: An improved fuser includes a heater which provides uniformity at the surface of a fuser roll that contacts an imaged sheet. The heater is configured to include a single resistive element shaped to heat multiple sheet sizes with independently controllable conductive traces connected to outer segments of the resistive element and adapted to supply electricity to separate sections of the resistive element in accordance with the size of sheet being fed through the fuser center registered and without the need for cold spot compensation.

Abstract: A fixing device includes a fixing rotation body heating and fixing an unfixed image onto a recording medium; a pressing rotation body pressing the recording medium to the fixing rotation body; a first temperature detection unit detecting a temperature of the fixing rotation body; and plural second temperature detection units detecting a temperature of the pressing rotation body. Further the fixing device selects a predetermined second temperature detection unit from the plural second temperature detection units depending on an operation mode of the fixing device, and the fixing device detects the temperature of the pressing rotation body by using the predetermined second temperature detection unit selected by the fixing device.

Abstract: A fixing device including a fixing rotational body and fixing images on sheets of various sizes, comprising: a main excitation coil heating the rotational body by electromagnetic induction and having an effective heating length L1 corresponding to a maximum-size sheet; an auxiliary excitation coil having an effective heating length L2 shorter than L1; a high-frequency power source supplying power to the main and auxiliary coils; and a switch selectively connecting the main or auxiliary coils to the power source, wherein the main coil is positioned along an outer circumferential surface of the rotational body, the auxiliary coil is positioned farther from the rotational body than the main coil is and layered on a central portion of the main coil in a longitudinal direction thereof, and L2 satisfies the following relationship: L2?L1·?2/?1, where ?1 and ?2 are thermal conversion efficiencies of the main and auxiliary coils, respectively.

Abstract: An image forming apparatus for forming an image includes a first control table and a second control table. The first control table includes information on widths of a recording sheet, categorized into a plurality of groups of different widths thereof in a direction perpendicular to a sheet transport direction. The second control table includes information on timing of the recording sheet transported to the fixing device based on the group to which a preceding recording sheet, belongs and the group to which a subsequent recording sheet belongs. When a certain width of the recording sheet belongs to the plurality of the groups in the first control table, the group to which the preceding recording sheet belongs is the group to which the subsequent recording sheet belongs.

Abstract: The heat fixing apparatus includes a fixing heater and a pressure roller. The fixing heater has a plurality of resistance-type heat generation layers which are different in heat distribution in the longitudinal direction perpendicular to the direction of conveying a recording material. The recording material P is heated when passed through a fixing nip portion formed between the fixing heater and the pressure roller. The pressurization conditions between the fixing heater and the pressure roller can be changed. The heat fixing apparatus includes a fixing member which adjusts the lengthwise heat distribution of the fixing heater by changing the applied current proportion of the plurality of resistance-type heat generation layers according to the pressurization conditions between the fixing heater and the pressure roller.

Abstract: Apparatuses useful for printing and methods of treating marking material on media are provided. An exemplary embodiment of the apparatuses includes a first member including a first outer surface; and a roll including a second outer surface forming a nip with the first outer surface. The second outer surface includes an inner portion having first and second axially-spaced edges, a roughened first high-friction surface axially outward from the first edge and a roughened second high-friction surface axially outward from the second edge. The first and second high-friction surfaces extend circumferentially around the roll and have a higher roughness than the inner portion. The inner portion and the first and second high-friction surfaces contact the first outer surface at the nip, and the first and second high-friction surfaces lie outside of a media path through the nip.

Abstract: A fixing device includes a heating rotating member that generates heat by induction heating; an induction coil that generates magnetic flux for induction heating; and a magnetic member core section forming a magnetic path and including a first core section, a second core section, a magnetic flux shielding member, and third core sections. The magnetic flux shielding member is disposed at a side of an end portion of the first core section opposite to the second core section and separated from the end portion, and disposed at a position that is separated from the outer surface of the heating rotating member by a separation distance. The third core sections are disposed at a side of the magnetic flux shielding member facing the end portion of the first core section. At least one of the third core sections is movable to a first position and to a second position.

Abstract: In a fixing device thermally fixing toner images on recording sheets of various sizes, (i) a conductive heat generating rotational body configured to heat toner images, (ii) an excitation coil positioned along a part of an outer circumferential surface of the heat generating rotational body and configured to generate a magnetic flux to heat the heat generating rotational body by electromagnetic induction, and (iii) a demagnetization coil positioned close to the excitation coil so as to cover a part of the excitation coil and configured to cancel, when a toner image is being fixed on a smaller-sized recording sheet, a part of the magnetic flux generated by the excitation coil so that overheating is prevented in a non sheet-passing region, are provided. The demagnetization coil has a thickness smaller than a thickness of the excitation coil in an axis direction of the coils.

Abstract: A printing speed is adaptively set using Fuzzy inference, based on various printing environments including a printing medium width and the average amount of printing, so that the internal temperature of an apparatus can be stably maintained, and the use convenience can be enhanced.

Abstract: Plural main cores and plural sub-cores are arranged spaced apart from each other along a direction orthogonal to a rotating direction of a heat belt. The plural main cores are opposed to a first area where a sheet having first width in the heat belt passes. The plural sub-cores are opposed to second areas that are areas excluding the first area in an area where the sheet having second width larger than the first width in the heat belt passes. The plural sub-cores have thickness in the direction orthogonal to the rotating direction of the heat belt smaller than the thickness of the plural main cores.

Abstract: An iso-thermalizing printer structure can be used to provide temperature uniformity across a width of a printer fuser roll or fuser belt. Various embodiments are contemplated, including a solid natural graphite shaft, a solid natural graphite core having a sleeve of metal such as aluminum, and other flexible and rigid structures which can comprise natural or synthetic graphite.

Abstract: An excitation coil positioned along an axial direction of a fixing rotational body having a heat generating layer causes the heat generating layer to generate heat by electromagnetic induction. Magnetic flux shielding members positioned outside the excitation coil in a radial direction of the fixing rotational body cover at least one end of a maximum sheet passing region. A controller moves the magnetic flux shielding members along the excitation coil, and when a fed sheet has a width smaller than a width of the maximum sheet passing region, a center hole of the excitation coil is more widely covered. In a plan view, a circumference of each of the magnetic flux shielding members partially and obliquely crosses with the center hole in the axial direction of the fixing rotational body.

Abstract: A disclosed fusing device includes a fusing part; a pressing part rotatably pressed against the fusing part to form a fusing nip for fusing a toner image onto a sheet; a capacitor; a center heater for heating a center portion of the fusing part; an edge heater for heating edge portions of the fusing part; an auxiliary heater for heating the fusing part; and a control unit configured to continuously turn off the edge heater and to turn on the center heater and the auxiliary heater to heat the fusing part during a fusing process of one or more small-size sheets having a width less than that of the heat generating portion of the center heater. The control unit is configured to turn on the edge heater to heat the fusing part when the capacitor stops discharging electricity during a consecutive fusing process of multiple small-size sheets.

Abstract: Fusers, printing apparatuses and methods of fusing toner on media are disclosed. An embodiment of a fuser for heating media includes a fuser roll including an outer portion having a first outer surface; a voltage source connected to the outer portion and adapted to supply voltage to the outer portion to heat the first outer surface; a pressure roll having a second outer surface; and a nip between the first and second outer surfaces. The first and second outer surfaces are adapted to contact a medium at the nip.

Abstract: An image forming apparatus includes an image carrier, a developing unit, a transfer unit, and a fixer to fix an image formed on a sheet and includes a rotary heat generator including a heat generation layer, a pressure member to form a nip with the rotary heat generator to sandwich the sheet therebetween, an excitation coil disposed facing the rotary heat generator, to inductively heat the heat generation layer, a demagnetization coil disposed facing the heat generation layer, to generate magnetic flux that partly counteracts magnetic flux generated by the excitation coil and a fixer controller to control activation of the excitation coil as well as the demagnetization coil before a second image formation job after completion of a first image formation job in which an image is formed on a sheet of recording media whose width is smaller than a maximum sheet width usable in the fixer.

Abstract: An image fixing apparatus includes a fixing member, a magnetic flux generator, a heat member, a core, and a magnetic flux adjuster. The fixing member fixes the toner image onto the recording medium. The magnetic flux generator generates a magnetic flux. The heat member has a heat layer which is heated inductively by the magnetic flux generated by the magnetic flux generator and heats the fixing member. The core faces the magnetic flux via the heat member. The magnetic flux adjuster is configured to vary a heating range of the heat member in the width direction. The heat layer has a predetermined Curie point.

Abstract: To provide a technique for preventing a temperature rise in a non-sheet passing areas in a fixing device. The fixing device includes: a heating rotational member that includes at least one roller and heats a toner transferred on a sheet; a pressing roller that nips and carries the sheet in cooperation with the heating rotational member; a heating device that heats the heating rotational member; and heat pipes arranged, on the inside of at least one of the roller of the heating rotational member and the pressing roller, in ranges on both the sides in an axial direction of the roller from positions closer to the center in the axial direction than both the ends of a minimum sheet passing range in the axial direction of the roller of the nipped and carried sheet to positions further on the outer sides in the axial direction than both the ends of a maximum sheet passing range.

Abstract: The heater includes an elongated substrate, two electrodes disposed along a longitudinal direction of the substrate, and a heat generation resistive member connected between the two electrodes. The heat generation resistive member is formed on the substrate by one of a sputtering method and a vapor deposition method. The uniform heat generation distribution of a heat generation resistive member in a heater can be achieved so as to reduce a temperature difference between a pass-through area through which a recording material passes and a no sheet pass-through area through which the recording material does not pass.

Abstract: A fixing apparatus includes a control circuit which controls the electrifying to a first heater so that a temperature detected by a first temperature detection portion reaches a first target temperature and controls the electrifying to a second heater so that a temperature detected by a second temperature detection portion reaches a second target temperature, when warm-up is initiated, and, when the warm-up initiated, if an initial temperature of a rotary member is below a predetermined temperature, the control circuit sets the first target temperature to a temperature value greater than the first target temperature set when the initial temperature of the rotary member is greater than the predetermined temperature and sets the second target temperature to a temperature value greater than the second target temperature set when the initial temperature of the rotary member is greater than the predetermined temperature.

Abstract: A printer includes a system for cooling an image receiving member. The image receiving member cooling system includes an image receiving member having a first end and a second end, a first heater mounted within the image receiving member for heating the image receiving member in the vicinity of the first end, a second heater mounted within the image receiving member for heating the image receiving member in the vicinity of the second end, a first temperature detector located proximate the first end of the image receiving member, a second temperature detector located proximate the second end of the image receiving member, a fan mounted at one end of the image receiving member, and a controller electrically coupled to the first and the second temperature detectors and the fan, the controller for activating the fan to move air from the end at which a higher temperature is detected past the other end.

Abstract: A segment and heater fuser roll is disposed for a printing device including a plurality of heating elements in a preselected order relative to a voltage return. A plurality of voltage taps are disposed for applying selected power to ones of the plurality of heater elements. The heater elements vary in power density per unit length.

Abstract: Fusers, printing apparatuses and methods of fusing toner on media are disclosed. An embodiment of a fuser for fusing toner on a medium includes at least two modules arranged along a process direction of the medium, each module having an ON state in which the module discharges a hot gas and an OFF state in which the module does not discharge the hot gas; and a controller connected to the modules for controlling the ON/OFF state of each module to control the discharge of the hot gas from each module onto the medium as the medium is transported past the modules in the process direction.

Abstract: A fixing unit (14) of an image forming apparatus (1) includes a heating member (48) having a first area where a sheet does not come into contact with the heating member (48) and a second area where the sheet comes into contact with the heating member (48). The fixing unit (14) further includes a coil (52) forming a magnetic field, cores (54,56) forming a magnetic path near the coil (52), a nonmagnetic magnetism adjusting member (90) arranged on the magnetic path and having a closed frame, and a switcher (58,60) capable of switching the magnetism adjusting member (90) between a first state where the magnetism adjusting member (90) generates an induction current resulting from the magnetic field to shield the magnetism in the first area, and a second state where the magnetism adjusting member (90) generates no induction current and the magnetism is not shielded in the first area.

Abstract: An induction heating device of the invention is made to have a two-layer structure in which at an end of a magnetic core of an induction current generating coil, a litz wire of outside three turns is stacked on a litz wire of inside three turns. The width of a joint portion between plural induction current generating coils is made narrow, and a mutual induction current generated at the joint portion is reduced. Further, the whole length of the litz wire is shortened without changing the length of the magnetic core of the inductor current generating coil.

Abstract: In an image forming apparatus having a fixing rotor (22) that is driven to rotate and fixes an image by heating a recording paper while conveying the paper pressurized against the rotor, an excitation coil (24) that is provided extending in an axial direction along the fixing rotor (22) and causes induction heating by applying an alternating magnetic field to the fixing rotor (22), and a demagnetizing coil (25) that is provided superposed on an end of the excitation coil (24) and is able to partially diminish a magnetic flux generated by the excitation coil (24), by making the shape of the portion that belongs to the demagnetizing coil (25) and overlaps the excitation coil (24) has an asymmetrical shape have no axis of symmetry in the direction in which the recording paper is conveyed, a trouble due to overheating and defective fixing due to a shortage in the generation of heat can be reduced even when a plurality of kinds of recording papers of slightly different sizes are used.

Abstract: In an induction heating fixing device according to the invention, a first induction heating coil that generates an induced current across the total length of a heat roller is provided on the outer circumference of the heat roller having a metal conductive layer. A second induction heating coil that generates an induced current at a central part of the heat roller is provided, which crosses the first induction heating coil and is arranged on the outer side than the first induction heating coil. With the first induction heating coil, the heat roller is heated across the total length without generating any uneven temperature. On-off control of the first induction heating coil and the second induction heating coil is carried out, and the temperature distribution in the longitudinal direction of the heat roller is kept constant irrespective of the size of a sheet of paper P.

Abstract: A fixing device includes a magnetic flux generator, a rotating heat generation member, a magnetic flux adjuster, and a driver. The magnetic flux generator generates a magnetic flux. The rotating heat generation member rotates and applies heat to a recording medium bearing an image, and includes a heat-generating layer to generate heat using the magnetic flux generated by the magnetic flux generator. The magnetic flux adjuster is provided outside the rotating heat generation member, and decreases the magnetic flux applied to the heat-generating layer at least in a desired area in an axial direction of the rotating heat generation member. The driver changes the desired area by driving the magnetic flux adjuster in a direction of rotation of the rotating heat generation member.

Abstract: A fixing unit includes: a shaft; a heatable rotating member, mounted for rotation on the shaft, for fixing an image on a recording medium, the heatable rotating member having a heat generating layer heatable via a magnetic flux; a magnetic flux generator configured to generate the magnetic flux, the magnetic flux generator being provided proximal to the heatable rotating member; and a supporting frame having a shaft supporter configured to support an end of the shaft on which the heatable rotating member is mounted, the shaft supporter being positioned outside of an end portion of the magnetic flux generator.

Abstract: The contact rate between a heater 1 and a heater holder 2 is made higher at both ends in the longitudinal direction of the heater than at the center. Alternatively, the per-unit-length volume of the heater holder 2 in the longitudinal direction is made larger at the both ends in the longitudinal direction of the heater. In this configuration, the heat generated by the heater can easily escape into the heater holder side at the both ends but cannot easily escape into the heater holder side at the center. Although the per-unit-length heat amount in the longitudinal direction of the heater 1 may be even, it is also possible to set the heat amount distribution in such a way that the heat amount at the both ends is larger than that at the center.

Abstract: In an image forming apparatus having a fixing rotor (22) that is driven to rotate and fixes an image by heating a recording paper while conveying the paper pressurized against the rotor, an excitation coil (24) that is provided extending in an axial direction along the fixing rotor (22) and causes induction heating by applying an alternating magnetic field to the fixing rotor (22), and a demagnetizing coil (25) that is provided superposed on an end of the excitation coil (24) and is able to partially diminish a magnetic flux generated by the excitation coil (24), by making the shape of the portion that belongs to the demagnetizing coil (25) and overlaps the excitation coil (24) has an asymmetrical shape have no axis of symmetry in the direction in which the recording paper is conveyed, a trouble due to overheating and defective fixing due to a shortage in the generation of heat can be reduced even when a plurality of kinds of recording papers of slightly different sizes are used.

Abstract: Disclosed herein is a fusing device having an improved heating structure. The fusing device is configured to apply heat and pressure to fix a developer to a print medium and includes a pressure device and a heating device. The heating device includes a heat radiating member extending along a longitudinal direction of the fusing device and terminal parts disposed at both ends of the heat radiating member. Contact points at which current is supplied to the heat radiating member through the terminal parts can be adjusted to change the effective width of heating area.

Abstract: A fixing device for fixing a toner image onto a recording medium, includes: a belt member rotatably provided; a heating section that heats the belt member; a pressurization member, placed so as to be pressed against the belt member, that forms a nip portion to allow the recording medium to pass through between the pressurization member and the belt member; and an uniforming section that uniforms a temperature distribution in a longitudinal direction of the pressurization member.

Abstract: A segment and heater fuser roll is disposed for a printing device including a plurality of heating elements in a preselected order relative to a voltage return. A plurality of voltage taps are disposed for applying selected power to ones of the plurality of heater elements. The heater elements vary in power density per unit length.

Abstract: In order to efficiently utilize the energy of the flux leaked from the vicinities of the edges of a fixing roller having a part to be heated, which is made of magnetic material that has Curie point, the energy of the leaked flux is stored to be utilized as need arises, or is utilized to heat the vicinity of the center of the fixing roller.

Abstract: A fixing device includes a fixing section, a sheet-width detector, a heating-width changing mechanism, a mixed feeding detector, and a controller. The fixing section includes at least a fixing member that fixes a toner image on a recording medium upon application of heat thereto. The sheet-width detector detects a width of the recording medium and outputs a sheet-width signal. The heat-width changing mechanism changes a heating width of the fixing member. The mixed feeding detector detects whether or not mixed feeding of a plurality of sheets of the recording medium having different widths is performed during a successive sheet feeding, and outputs a mixed feeding signal. The controller controls the heating-width changing mechanism to control the heating width based on the sheet-width signal and the mixed feeding signal.

Abstract: An image heating member includes a first region having a Curie temperature higher than a preset temperature, and a second region having a Curie temperature lower than the Curie temperature of the first region. A width of the first region in a conveying direction of a recording material is equal to or larger than a width of the recording material of a maximum size to be fed. The second region is provided outside the first region.

Abstract: An image forming apparatus comprising an image forming unit that forms an image on a sheet, a sheet feeder that feeds the sheet to the image forming unit, a detector that detects a width of the sheet, a setting unit that is operated by a user to input a width and a length of a nonstandard-size sheet, a determination unit that determines whether the width of the nonstandard-size sheet detected by the detector and the width of the nonstandard-size sheet inputted by the user to the setting unit differ from each other, when the image is printed on the nonstandard-size sheet and a controller that controls the image forming unit to form the image, based on the width of the sheet detected by the detector and the length of the sheet inputted by the user to the setting unit, when the determination unit determines that the detected width and the inputted width differ from each other.

Abstract: An image apparatus which minimizes temperature differences between end portions and a central portion of a print medium includes heater members having different heat distributions, a temperature detecting unit for detecting a temperature of an area where a print medium passes through, a heat controlling unit for controlling a fusing unit temperature by an individual heat controlling of the heater members based on the temperature detected by the temperature detecting unit, and a rate determination unit for determining a divisional rate of heat to be charged per unit time to the fusing unit by means of the heater members. The rate determination unit determines the divisional rate based on the fusing condition input and the heat controlling unit which controls the heater members individually on the basis of the divisional rate determined by the rate determination unit.

Abstract: An image heating apparatus includes a heating roller for heating an image on a recording material; a coil unit disposed in said heating roller and including a coil for induction heat generation in said heating roller; a supporting member for rotatably supporting said heating roller, wherein said supporting member including a holding portion for substantially non-rotatably holding said coil unit.

Abstract: An image forming apparatus includes an image carrier, a developing unit, a transfer unit, and a fixer to fix an image formed on a sheet and includes a rotary heat generator including a heat generation layer, a pressure member to form a nip with the rotary heat generator to sandwich the sheet therebetween, an excitation coil disposed facing the rotary heat generator, to inductively heat the heat generation layer, a demagnetization coil disposed facing the heat generation layer, to generate magnetic flux that partly counteracts magnetic flux generated by the excitation coil and a fixer controller to control activation of the excitation coil as well as the demagnetization coil before a second image formation job after completion of a first image formation job in which an image is formed on a sheet of recording media whose width is smaller than a maximum sheet width usable in the fixer.

Abstract: A heater controller system for a fusing apparatus configured for fusing marking material to a substrate in a printing system includes a power source for supplying power to a heating element having at least two sections. The controller system further includes at least one switch configured to selectively control at least two bidirectional switches for selectively providing current supplied by the power source to at least one of the at least two sections during operation of said heater controller system in one of at least two modes of operation, each of the at least two modes of operation corresponds to a particular size of said substrate.

Abstract: In an embodiment, in a fixing apparatus provided with a plurality of fixing heaters having heat distribution characteristics that are different from each other inside a fixing roller, and an image forming apparatus provided with the fixing apparatus, an auxiliary heater is provided, the auxiliary heater being provided inside the fixing roller and to which power is distributed only during the warm-up period until the fixing roller in a lower temperature state reaches a predetermined fixing temperature.

Abstract: An image heating apparatus includes a heating rotatable member for heating a toner image on a recording material at a nip; an axial flow fan for cooling the heating rotatable member at a longitudinal end portion thereof; wherein an axis of the axial flow fan extends from its outlet disposed adjacent the longitudinal end portion inclinedly toward a longitudinally central portion of the heating rotatable member.

Abstract: A fixing apparatus includes a control circuit which controls the electrifying to a first heater so that a temperature detected by a first temperature detection portion reaches a first target temperature and controls the electrifying to a second heater so that a temperature detected by a second temperature detection portion reaches a second target temperature, when warm-up is initiated, and, when the warm-up initiated, if an initial temperature of a rotary member is below a predetermined temperature, the control circuit sets the first target temperature to a temperature value greater than the first target temperature set when the initial temperature of the rotary member is greater than the predetermined temperature and sets the second target temperature to a temperature value greater than the second target temperature set when the initial temperature of the rotary member is greater than the predetermined temperature.

Abstract: A fixing device includes: a heat member; a press member; a plurality of heat source members; temperature detectors; temperature control units that control outputs from the respective heat source members so that detected temperatures that the respective temperature detectors detect become preset controlled temperature; a processing target determining unit that determines whether at least one sheet to be subjected to the fixation includes a medium size sheet; and a controlled temperature determining unit that sets the controlled temperature of the heat source member corresponding to the temperature detection target area where the sheet does not pass to a temperature higher than the controlled temperature of the heat source member corresponding to the temperature detection target area where the sheet passes if it is determined that the medium size sheet is included.

Abstract: The heater includes an elongated substrate, two electrodes disposed along a longitudinal direction of the substrate, and a heat generation resistive member connected between the two electrodes. The heat generation resistive member is formed on the substrate by one of a sputtering method and a vapor deposition method. The uniform heat generation distribution of a heat generation resistive member in a heater can be achieved so as to reduce a temperature difference between a pass-through area through which a recording material passes and a no sheet pass-through area through which the recording material does not pass.

Abstract: A heat roller having a cylindrical sheet-like heating element having a resistance member embedded in an insulating member. The sheet-like heating element is arranged between an inner tube and an outer tube. The outer tube is formed so as to be longer than the inner tube for reducing non-uniformity in heat of the heat roller. Further, a thermal expansion coefficient of a material of the outer tube is greater than that of a material of the inner tube. Moreover, a triple-tube heat roller is provided.

Abstract: A fixing device of this invention enables variable control of power to be supplied to a heat roller side or a press roller side in accordance with the temperature of the heat roller and the press roller while each mode is carried out. The heating range of a first induction heating coil on the heat roller side and the heating range of a first halogen lamp heater on the press roller side are set differently. In a copy mode, the temperature of the heat roller and the press roller is controlled in detail, and also controlled in accordance with the size of a sheet paper. In a copy standby mode, only the power required for maintaining a set temperature is supplied.

Abstract: A disclosed fusing device includes a fusing part; a pressing part rotatably pressed against the fusing part to form a fusing nip for fusing a toner image onto a sheet; a capacitor; a center heater for heating a center portion of the fusing part; an edge heater for heating edge portions of the fusing part; an auxiliary heater for heating the fusing part; and a control unit configured to continuously turn off the edge heater and to turn on the center heater and the auxiliary heater to heat the fusing part during a fusing process of one or more small-size sheets having a width less than that of the heat generating portion of the center heater. The control unit is configured to turn on the edge heater to heat the fusing part when the capacitor stops discharging electricity during a consecutive fusing process of multiple small-size sheets.