Abstract: A temperature detection unit is arranged in a position between a magnetic field generation coil and a magnetic core that lies inside a heat generation member. A cut portion for exposing the temperature detection unit through the magnetic core has a thickness when seen in a cross section in the direction of a magnetic flux.

Abstract: Embodiments in accordance with the present invention encompass a fixing device that includes an endless heat generating section including a conductive layer, an induction-current generating section configured to generate an induction current in the conductive layer, a temperature-sensitive magnetic body present in a position opposed to the induction-current generating section via the heat generating section, and a magnetic plate present in a position opposed to the heat generating section via the temperature-sensitive magnetic body.

Abstract: A printer is provided having a fuser assembly having a belt, a heater to heat the belt, a backup roll positioned to engage the belt thereby defining a fusing nip with the belt, a main temperature sensor associated with the heat transfer member, the first temperature sensor associated with the backup roll for sensing a temperature of a portion of the backup roll, the second temperature sensor associated with a distal end region of the heat transfer member for sensing the temperature of the distal end region. A controller is coupled to the fuser assembly for controlling a throughput of the printer based on at least one of the backup roll temperature and the temperature at the distal end region of the heater.

Abstract: An electromagnetic induction heating device includes a heat generation body, a heating rotary body, a magnetic filed generating unit and a magnetic path forming member. The heat generation body generates heat through electromagnetic induction. The heating rotary body receives the heat and rotates. The magnetic field generating unit is opposed to the heating rotary body and generates a magnetic field for causing the heat generation body to produce heat through the electromagnetic induction. The magnetic path forming member is opposed to the magnetic filed generating unit across the heating rotary body. The magnetic path forming member includes controlling portions and a continuous portion. The controlling portions control a magnitude of eddy current which is generated through the electromagnetic induction. The continuous portion allows heat transfer along a direction of an axis of the heating rotary body.

Abstract: An image heating apparatus includes an image heating roller, an excitation coil provided outside of the roller for causing electromagnetic induction heat generation in the roller, a magnetic core, provided opposed to the roller with the excitation coil therebetween, for directing a magnetic flux produced by the excitation coil to the roller, a retracting mechanism for retracting the magnetic core from the excitation coil, coil holder for holding a side of the excitation coil adjacent to the roller, and first and second pressing members for pressing the excitation coil against the holder in each of longitudinally opposite portions that are outside beyond the magnetic core.

Abstract: A non-contact power supply unit including a secondary coil supplies an alternating voltage to multiple heat generation layers provided in a heat generation film. In one of the heat generation layers, a loop is provided as a variable impedance circuit in which the impedance changes according to the frequency. A capacitance element in which the impedance changes according to the frequency is provided in the loop. The heat generation amounts of the heat generation layers are switched by changing the frequency of the alternating voltage generated in the secondary coil according to the size of the recording material that is the heating target.

Abstract: A fixing device includes: an induction coil; heating rotator; pressurizing rotator disposed to face the heating rotator; fixing nip; and magnetic core unit. The heating rotator is disposed in a region through which a magnetic flux generated by the induction coil passes and rotates about a first rotational shaft. The magnetic core unit forms a magnetic path circularly encloses the induction coil. The magnetic core unit includes arch core portions and a core supporting member supporting these portions. The arch core portions each have an arch shape facing the heating rotator across the induction coil and are arranged at intervals in a direction of the first rotational shaft. Each arch core portion has first engaging portions formed respectively at both ends thereof and a core main body formed between the first engaging portions. The core supporting member has second engaging portions with which the first engaging portions are engageable.

Abstract: A heating device capable of accurately determining a change in the state of a to-be-heated member, caused in a narrow area. An induction heating coil generates magnetic flux by flow of electric current therethrough. The fixing belt generates heat by the action of the magnetic flux generated by the induction heating coil. A first antenna is disposed at a location where the magnetic flux generated by the induction heating coil can be detected assuming that there is no fixing belt. A second antenna is disposed such that at least some area of the second antenna overlaps the first antenna. A control circuit determines whether or not a state of the fixing belt has changed, based on a result of detection by the first antenna and a result of detection by the second antenna.

Abstract: A boosting circuit includes a switch element, a first coil, a second coil, and a capacitor. The switch element generates a first alternating current voltage having a first frequency from a direct current voltage. The first coil generates a magnetic field around the first coil with a flow of the first alternating current voltage having the first frequency in the first coil. The first coil also induces an eddy current in the object with the magnetic field to inductively heat the object. The second coil is cumulatively connected to the first coil. The capacitor is connected to the first coil and the second coil in a parallel manner.

Abstract: An induction heating type fusing device and an image forming apparatus including the fusing device. The fusing device includes a magnetic flux generator and a compressing roller outside a fusing belt, first and second fusing rollers and a nip guide inside the fusing belt. The compressing roller compresses against the first and second fusing rollers and the nip guide to form nips, while the fusing belt is disposed between the compressing roller and the first and second fusing rollers and the nip guide.

Abstract: Methods and an apparatus are provided for heating a material. The apparatus includes a roller that includes at least one susceptor contained therein, and at least one induction coil coupled to the roller. The induction coil is configured to induce a magnetic field in the susceptor to facilitate increasing a temperature of the roller.

Abstract: An induction heating workcoil has a ferrite core on which are wound multiple layers of an electrically conductive material. To cool the winding, solid thermal conductors are inserted between the multiple layers of the winding to provide a thermal interface with the multiple layers. The workcoil can also have a hollow tube that is wound on the outside of the winding with the tube having a liquid circulating through it to cool the winding. The core can have a cross-shaped top and an I-shaped leg with the multiple layers of the winding wound on the leg of the core. The solid thermal conductors can extend above the height of the windings so that the heat to be dissipated is transferred to the upper portion of the workcoil. The multiple layers of the winding are tightly wound on the solid thermal conductors to maximize the thermal interface.

Abstract: An induction heating type fusing device and an image forming apparatus including the fusing device. The fusing device includes a magnetic flux generator and a compressing roller outside a fusing belt, first and second fusing rollers and a nip guide inside the fusing belt. The compressing roller compresses against the first and second fusing rollers and the nip guide to form nips, while the fusing belt is disposed between the compressing roller and the first and second fusing rollers and the nip guide.

Abstract: A fixing unit of an image forming apparatus includes a coil arranged along an outer surface of the heating member and generating a magnetic field, a first core arranged opposite the heating member with respect to the coil and forming a magnetic path, a second core so fixed between the first core and the heating member with respect to a direction in which the coil generates the magnetic field, as to form the magnetic path together with the first core, a shielding member positioned outward of the second core and shielding the magnetism in the magnetic path, and a magnetism adjusting unit moving the shielding member outward of the second core to switch the position of the shielding member between a shielding position where the shielding member shields the pass of the magnetism and a retracted position where the shielding member permits the pass of the magnetism.

Abstract: An image forming apparatus which is capable of detecting occurrence of an abnormality that a fixing member which is actually in an unpressurized state is detected to be in a pressurized state, and supply of electric power to a heating member is continued. A fixing device includes a fixing belt and a pressure roller. The fixing belt and the pressure roller are pressed against each other such that a nip is formed therebetween, for nipping and conveying a transfer material through the nip while heating and pressing the same. A pressurizing unit selectively switches between a pressurizing state and an unpressurizing state. When the pressurizing unit is in the pressurized state, a heater heats the fixing belt. The heating of the fixing belt is stopped based on a temperature detected by a thermistor after a lapse of a predetermined time period from start of the heating.

Abstract: In a fixing device, a pressing member rotates in a predetermined direction of rotation. A flexible fixing member is disposed opposite the pressing member to rotate in accordance with rotation of the pressing member. A nip formation member is provided inside a loop formed by the fixing member and pressed against the pressing member via the fixing member to form a nip between the fixing member and the pressing member through which a recording medium bearing a toner image passes. A contact member pressingly contacts an outer circumferential surface of the rotating fixing member at both ends of the fixing member in an axial direction thereof.

Abstract: The sealing roll includes a stationary internal shaft and an inductively heatable roll jacket supported with freedom to rotate around the shaft. A plurality of induction coils is wound around the shaft over ferrites, which are open to the outside. Cables for the induction coils are laid through a cable conduit in the shaft for connection to an external induction generator. A water cooling channel for indirectly cooling the induction coils is also arranged in the shaft. A cavity is formed in at least an axial subsection of the sealing roll between the roll jacket and the shaft, and at least part of a temperature detection device is arranged in the cavity or adjacent to the cavity so that an IR temperature sensor receives radiation emitted by the roll jacket and thus detects a temperature of the roll jacket.

Abstract: A sheet feeding apparatus is disclosed that includes a plurality of size sensors configured to be arranged in line and to detect a sheet set into a predetermined position; a feeding part configured to feed the sheet set into the predetermined position to a scan position; and a controller configured to control the feeding part to feed the sheet based on two detect signals output from two size sensors among the plurality of the size sensors.

Abstract: An image heating apparatus includes a belt unit, a coil unit, a rotatable driving member, and positioning and urging mechanisms. The belt unit includes an endless belt to heat a toner image on a sheet at a nip portion. The coil unit opposes an outer surface of the belt and generates a magnetic flux for heating the belt. The driving member rotates the belt and forms the nip portion with the belt. The positioning mechanism positions the coil unit with respect to the belt unit and includes two positioning portions on each side of the coil unit with respect to a longitudinal direction thereof. The urging mechanism urges the coil unit toward the belt unit. The coil unit is supported by the belt unit at three of the four positioning portions.

Abstract: An induction heating device includes a take-off roller, the take-off roller adapted to unwind a wound electrode plate having a coating portion and a non-coating portion, a guide roller adapted to feed the electrode plate, an induction heater above the guide roller, the induction heater being spaced a predetermined distance from the guide roller and the electrode plate, and a winding roller, the winding roller adapted to wind the electrode plate fed from the guide roller.

Abstract: A fixing unit of an image forming apparatus includes a coil arranged along an outer surface of the heating member and generating a magnetic field, a first core arranged opposite the heating member with respect to the coil and forming a magnetic path, a second core so fixed between the first core and the heating member with respect to a direction in which the coil generates the magnetic field, as to form the magnetic path together with the first core, a shielding member positioned outward of the second core and shielding the magnetism in the magnetic path, and a magnetism adjusting unit moving the shielding member outward of the second core to switch the position of the shielding member between a shielding position where the shielding member shields the pass of the magnetism and a retracted position where the shielding member permits the pass of the magnetism.

Abstract: An induction heating type fusing device to reduce the size of an induction coil and an image forming apparatus having the same, and a control method thereof. The image forming apparatus includes a printing device to form an image on a recording medium, and a fusing device to fix the image to the recording medium. The fusing device includes a heating member arranged to transfer heat to the recording medium and having a main heater and a sub heater, and an induction coil having a width equal to or less than a width of the recording medium and arranged in an axial direction of the heating member to generate a magnetic field acting on the main heater. The sub heater is arranged inside the heating member to heat both ends of the main heater.

Abstract: An image heating apparatus includes a coil for generating a magnetic flux by a current flowing therethrough; an image heating member having an electroconductive layer in which an eddy current is produced by the magnetic flux by which heat is generated, the image heating member being effective to heat an image on a recording material; an electroconductive magnetic flux adjusting member movable from a first position and a second position to decrease the eddy current produced in the image heating member by the magnetic flux; a temperature sensor for sensing a temperature of image heating member; electric power control means for control electric power supplied to the coil on the basis of an output of the temperature sensor, wherein the electric power control means changes an electric power condition to be supplied to the coil before start of the movement from the first position to the second position of magnetic flux adjusting member.

Abstract: An induction heating unit enabling to attaching coil on coil attaching surface of bobbin with a high degree of accuracy, and a fixing device capable of maintaining the distance between the coil and the member to be heated at a high degree of accuracy, ensuring uniformity of temperature distribution of the member to be heated, rising temperature at a high speed, and enhancing quality of fixation. In an induction heating unit 30 including a magnetizing coil 39 attached on a coil bobbin 38 which is disposed outside of annular body 19 to be heated, the unit including: a layer of elastic adhesive 44a provided on the outer surface of the coil bobbin 38; a magnetizing coil 39 provided on the layer of elastic adhesive 44a, the magnetizing coil 39 being wound beforehand following an attaching surface; and a layer of elastic adhesive 44b provided on the magnetizing coil 39.

Abstract: A heating device for heating a rotary heated member includes a heater and a temperature detector. The heater faces the rotary heated member to heat the rotary heated member. The temperature detector faces the rotary heated member via the heater to detect a temperature of the rotary heated member. The heater includes a housing provided between the temperature detector and the rotary heated member, a through-hole provided in the housing via which the temperature detector faces the rotary heated member, and a channel provided in the housing at a position downstream from the through-hole in a direction of rotation of the rotary heated member through which an air current generated in a gap between the heater and the rotary heated member moves. The channel has a hollow cross-sectional area greater than a hollow cross-sectional area of the through-hole.

Abstract: There are provided a first excitation coil that is wound so as to have an axis in the same direction as that of a shaft of a heating roller and that is connected to a first power source, and a second excitation coil that is wound so as to have an axis in a direction substantially orthogonal to the shaft of the heating roller and that is connected to a second power source. The second excitation coil has parallel portions that extend in parallel to an axial direction of the first excitation coil and two folded sections provided at respective ends of the parallel portions. The two folded sections are provided along a circumference of the first excitation coil in such a way that circular arcs of the respective folded sections become opposite in direction to each other. Thus, the maximum available power is increased. When rapid warm-up is required, heating is caused by a coil connected to the auxiliary power source, to thus shorten a warm-up time.

Abstract: A fixing apparatus which heat-fixes a toner image transferred onto a sheet, including: a heating device configured to generate eddy currents in a conductive heating element using a magnetic core and an exciting coil to produce heat; a core moving unit configured to move the core; a current detecting unit configured to detect a current flowing through the exciting coil; and an abnormal signal output unit configured to output a signal indicating an abnormality when a difference between a first current value and a second current value is smaller than a predetermined threshold value, the first current value being detected by the current detecting unit before the core is moved by the core moving unit, the second current value being detected by the current detecting unit after the core is moved by the core moving unit.

Abstract: A fixing device is provided with a heating member, a pressing member, a coil, a fixed core, a movable core and a shielding member provided on the movable core and a position switching unit moving the shielding member between a shielding position where a ring part shields magnetism and a retracted position where the ring part does not shield magnetism. A first area requiring magnetic shielding and a second area not requiring magnetic shielding are selectively set in the heating member. The shielding member includes a first annular portion provided at a position corresponding to a boundary part between the first and second areas, and the first annular portion has a shape closed in a circumferential direction and is electrically insulated at a circumferential part when viewed in an axial direction of the movable core.

Abstract: A cylinder heater useful in fabricating sleeves for high pressure pump liners comprises a support rotatably supporting a hollow circular cylinder having a metallic powder layer contacting a portion of its inner surface. A vibration sensor indicates vibration of the cylinder, and at least one temperature sensor indicates at least one temperature of the cylinder. At least one circumferential induction heating coil around the cylinder is positionable via the support along the longitudinal axis of cylinder rotation. Longitudinal position and power output of at least one heating coil, and cylinder rotational speed, are adjusted by a controller communicating with the support, the vibration sensor, at least one temperature sensor, and at least one heating coil. Controlled heating of the cylinder and the metallic powder layer results in a stratified abrasion-resistant fused metallic layer on the cylinder's inner surface. The fused layer may be honed to make a liner sleeve.

Abstract: A heating roller performs electromagnetic induction heating, and includes a first exciting coil that heats the heating roller, a first degaussing coil that decreases magnetic fields of the first exciting coil, and a first axial direction core that guides magnetic fluxes, to make up a magnetic circuit between the first axial direction core and the heating roller. The width of a heat zone is controlled in agreement with a sheet feeding area. Thus, the capability to control a temperature increase in a non-sheet-feeding area of the heating roller is enhanced. Power can be saved during continual feeding of small recording sheets.

Abstract: Exemplary embodiments provide an induction heating member including a substrate and a heating layer disposed on the substrate. The heating layer includes carbon nanotubes and metal. An outer layer is disposed on the heating layer and includes a fluoropolymer.

Abstract: Provided is a low cost and highly safe electromagnetic induction heating device capable of uniformly heating an object to be heated. A work coil (26) has a basic coil (28) located at the innermost position, a first coil (30) located at the intermediate position, and a second coil (32) located at the outermost position, the latter two coils being connected in series to the basic coil (28). The first coil (30) and the second coil (32) are connected in parallel to each other. A switching circuit (16) for supplying a high-frequency current is connected to the first coil 30, and a second switching circuit 18 for supplying a high-frequency current is connected to the second coil 32.

Abstract: A fixing unit for fixing a toner image onto a sheet passing between a first element and a second element pressed against the first element includes a looped coil surface formed with a coil so that the coil surface generates a magnetic field for induction-heating the first element, the coil surface including an inner edge defining an opening region; an upright wall disposed inside the opening region, an opening being formed in the upright wall; a center core disposed along the opening region, the center core including a conductive shaft and a magnetic tube configured to at least partially cover the conductive shaft; and a nonconductive cap inserted into the opening, the nonconductive cap partially covering the conductive shaft to electrically insulate the coil from the conductive shaft.

Abstract: A fixing device includes: an induction coil; heating rotator; pressurizing rotator disposed to face the heating rotator; fixing nip; and magnetic core unit. The heating rotator is disposed in a region through which a magnetic flux generated by the induction coil passes and rotates about a first rotational shaft. The magnetic core unit forms a magnetic path circularly encloses the induction coil. The magnetic core unit includes arch core portions and a core supporting member supporting these portions. The arch core portions each have an arch shape facing the heating rotator across the induction coil and are arranged at intervals in a direction of the first rotational shaft. Each arch core portion has first engaging portions formed respectively at both ends thereof and a core main body formed between the first engaging portions. The core supporting member has second engaging portions with which the first engaging portions are engageable.

Abstract: A fixing device according to an embodiment of the present invention heats a metal conductive layer of a heat roller using an induction current generating coil. In order to supplement a heat capacity of the heat roller, a press roller having a large heat capacity is heated by a halogen lamp. During a start of activation of an image forming apparatus, when a printer control circuit is started, the supply of electric power to the halogen lamp is started before warming-up is started.

Abstract: An apparatus includes a rotatable image heater for heating a recording material, a coil, outside the heater, for generating magnetic flux for heating the heater and having an end outside an end of the heater with respect to the rotational axis direction, a pressor contacting the heater outer surface for forming a nip nipping and conveying the recording material, a metal member for pressing the pressor through the heater and having an end which is located outside the end of the heater and outside an end of the coil with respect to the rotational axis direction, and a magnetic flux confiner disposed inside the heater between the coil and the metal member, for confining the magnetic flux from the coil so as not to extend toward the metal member and having an end located outside the end of the heater with respect to the rotational axis direction.

Abstract: Systems and methods of inductively heating a fuser member in an electrophotographic device are disclosed. The systems and methods can include a heating component with a susceptor layer comprising carbon nanotubes (CNTs). An excitation unit with an electrical coil can be positioned a proximate distance from the heating component. Current through the electrical coil can inductively heat the susceptor layer and the heating component. The heat from the susceptor layer and the heating component can be used to fuse toner onto an image-receiving substrate. The CNTs can reduce electronic hardware costs in the electrophotographic device in relation to the costs associated with conventional materials.

Abstract: A fixer includes a fixing member with a rotary heat generator, a pressure member, an excitation coil disposed facing a heat generation layer of the rotary heat generator to generate magnetic flux that inductively heats the heat generation layer, a loop-shaped demagnetization coil unit disposed facing the heat generation layer to generate magnetic flux that partly counteracts the magnetic flux generated by the excitation coil, a first magnetic core disposed in a first area that is enclosed by both the excitation coil and the demagnetization coil unit, and a second magnetic core disposed in a second area that is outside a loop of the demagnetization coil unit and enclosed by the excitation coil. The first magnetic core and the second magnetic core are magnetically continuous in a rotary axial direction of the rotary heat generator. A fixing method fixes an image on the sheet used in a fixer.

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: A fixing device according to an embodiment of the invention is provided with a center coil and a side coil to induction heat a metal roller which supports a belt. An auxiliary pressurizing member which is adjacent to an opposing roller which supports the belt and presses the belt against a heat roller is provided. The distance from the center position of induction heating of a heat roller to an entrance of a nip is equalized to the distance from the center position of induction heating of the metal roller to the entrance of the nip. The distance from the temperature reading position of the heat roller to the center position of induction heating of the heat roller is equalized to the distance from the temperature reading position of the belt to the center position of induction heating of the metal roller.

Abstract: An image heating apparatus has a coil; a rotatable image heating member capable of generating heat by a magnetic flux generated by the coil to heat an image; a temperature detecting member; an electric power supply controller for controlling electric power supply to the coil; and an execution portion for executing a stand-by mode operation in which the image heating member is at rest, and the apparatus waits for input of an image formation signal while the electric power supply controller carries out its power supply control operation such that in the stand-by mode, along no longitudinal line on said image heating member, the temperature of the image heating member exceeds Curie temperature on an entirety of the longitudinal line.

Abstract: A heating device includes: a magnetic field generating unit generating a magnetic field; a heat-generating member generating heat due to electromagnetic induction of the magnetic field, and having a heat-generating layer of a thickness that is thinner than a skin depth; a temperature-sensitive member including a temperature-sensitive magnetic member whose magnetic permeability starts to decrease continuously from a magnetic permeability change start temperature that is in a temperature region that is greater than or equal to a set temperature and less than or equal to a heat-resistant temperature; and an approaching/separating mechanism maintaining the temperature-sensitive member in a state of being separated from the heat-generating member until before a temperature of the temperature-sensitive member reaches the set temperature, and causing the temperature-sensitive member to contact the heat-generating member at and after the time when the temperature-sensitive member reaches the set temperature.

Abstract: An induction heating type fusing device and an image forming apparatus including the fusing device. The fusing device includes a magnetic flux generator and a compressing roller outside a fusing belt, first and second fusing rollers and a nip guide inside the fusing belt. The compressing roller compresses against the first and second fusing rollers and the nip guide to form nips, while the fusing belt is disposed between the compressing roller and the first and second fusing rollers and the nip guide.

Abstract: A heating control device which is capable of detecting an abnormality of an object to be heated accurately. A power-supply unit applies the electric power to the electromagnetic induction heating coil. A magnetic flux detecting unit detects a magnetic flux emitted from the electromagnetic induction heating coil across the object, and outputs a voltage corresponding to the detected magnetic flux. A changing unit changes at least one of the detected magnetic flux voltage value and an abnormality detection threshold value based on relationship between an electric power set value that defines the electric power and an input voltage inputted to the power-supply unit. A determination unit compares the detected magnetic flux voltage value changed by the changing unit to the abnormality detection threshold value, and determines an abnormality of the object when the detected magnetic flux voltage value is larger than the abnormality detection threshold value.

Abstract: The fixing apparatus includes: a fixing member having base and conductive layers and fixing a toner onto a recording medium when the conductive layer is heated by electromagnetic induction; a magnetic field generating member generating an alternating-current magnetic field crossing the conductive layer; and a magnetic field inducing member arranged so as to face the magnetic field generating member across the fixing member, and inducing the magnetic field into itself or allowing the magnetic field to go through the member. The base layer and the magnetic field inducing member each contain a material having a magnetic permeability change onset temperature in a range from not less than a heating preset temperature of the fixing member to not more than a heatproof temperature of the fixing member. A thickness of the base layer is smaller than a skin depth of the layer at the heating preset temperature of the fixing member.

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: A heating device includes: a magnetic field generating unit that generates a magnetic field; a heat-generating member that is disposed so as to face the magnetic field generating unit, and generates heat due to electromagnetic induction of the magnetic field, and having a heat-generating layer of a thickness that is thinner than a skin depth; and a temperature-sensitive member that is disposed so as to face a side of the heat-generating member opposite a side at which the magnetic field generating unit is located, a magnetic permeability of the temperature-sensitive member starting to decrease continuously from a magnetic permeability change start temperature that is in a temperature region that is greater than or equal to a set temperature and less than or equal to a heat-resistant temperature. A convex portion, that projects-out toward the heat-generating member from a surface that faces the heat-generating member, is provided at the temperature-sensitive member.

Abstract: A fixing unit includes a rotatable fixing member and a rotatable pressure applying member. The rotatable fixing member has a heat generating layer to generate heat when subject to a magnetic flux. The rotatable pressure applying member contacts the rotatable fixing member and applies pressure to the fixing member. The rotatable fixing member and the rotatable pressure applying member form a nip therebetween, to which a recording medium is passed through to fix an image on the recording medium. The rotatable fixing member includes a magnetism regulating layer deformable when subject to pressure from the rotatable pressure applying member.

Abstract: An image forming apparatus includes a fixing unit fixing a toner image onto a sheet. The fixing unit includes a heating member having a sheet conveyed region that is set in accordance with the size of the sheet. The fixing unit further includes a coil generating magnetic field, a fixed core forming a magnetic path, movable cores forming a magnetic path together with the fixed core and arranged along the sheet conveyed region, a shielding member arranged on at least one movable core and shielding magnetism, and a magnetism adjustment unit rotating at least one movable core to switch the position of the shielding member between a shielding position where the shielding member is positioned inside the sheet conveyed region to shield the magnetism and a retracted position where the shielding member is positioned outside the sheet conveyed region to permit pass of the magnetism.

Abstract: A disclosed power supply device includes a voltage resonance circuit configured to include an output coil for boosting an input direct-current voltage to a predetermined voltage and outputting the boosted voltage to a load and also include a capacitor connected to the output coil; and a switching unit configured to be turned ON/OFF so as to control electric current supply to the output coil. An auxiliary resonance circuit is connected in parallel with the output coil so as to reduce switching losses without using a power control circuit for switching control.