JP5880342B2 - Image forming apparatus and fixing apparatus - Google Patents

Description

The present invention relates to an image forming apparatus and a fixing device.

There is known an induction heating fixing device in which a halogen heater is incorporated in a hollow portion of a pressure roller and energizes a coil at startup and energizes the halogen heater at a predetermined timing (Patent Document 1).
Also known is a fixing device that shortens the time to raise the heating roller to the required temperature by heating the heating roller in combination with an induction heating coil and a rod heater at the start-up and the initial stage of the fixing process. (Patent Document 2).

In the induction heating fixing device disclosed in Patent Document 1, each of the heating sources energized to the halogen heater and the coil does not exceed the limit current.
The fixing device disclosed in Patent Document 2 uses a different heater to reduce the warm-up time.

Japanese Patent Laid-Open No. 10-319749 JP 2006-078603 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide a fixing device and an image forming apparatus that can shorten the recovery time and reduce power consumption without exceeding the power allocated to the fixing device.

In order to solve the above-mentioned problem, an image forming apparatus according to claim 1,
Toner image forming means for forming a toner image;
A fixing member having a conductive layer and fixing the toner to the recording medium by electromagnetically heating the conductive layer;
A pressure member that conveys the recording medium between the fixing member and the fixing member;
A magnetic field generating means disposed opposite to the fixing member to generate a magnetic field;
Driving means for rotating the pressure member by following the fixing member;
Temperature detecting means for detecting the surface temperature of the fixing member;
Moving means for moving the pressure member to a state of being separated or pressed against the fixing member;
A temperature-sensitive heat storage member that is provided in contact with the inner peripheral surface of the fixing member while sliding, and generates heat by electromagnetic induction of the magnetic field to heat the fixing member;
A heating member that is provided in contact with the inside of the temperature-sensitive heat storage member and generates heat by supplying power to heat the temperature-sensitive heat storage member;
A heat storage member that is provided inside the heating member and stores heat;
A fixing device comprising:
Power supply means for supplying power to the magnetic field generating means and the heating member;
With
It is characterized by that.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect,
A power limit for limiting the power supplied by the power supply means within a range of preset maximum power to the sum of the first power supplied to the magnetic field generating means and the second power supplied to the heating member. With means,
It is characterized by that.

In order to solve the above problem, a fixing device according to claim 3 is provided.
A fixing member having a conductive layer and fixing the toner to the recording medium by electromagnetically heating the conductive layer;
A pressure member that conveys the recording medium between the fixing member and the fixing member;
A magnetic field generating means disposed opposite to the fixing member to generate a magnetic field;
Driving means for rotating the pressure member by following the fixing member;
Moving means for moving the pressure member to a state of being separated or pressed against the fixing member;
Temperature detecting means for detecting the surface temperature of the fixing member;
Moving means for moving the pressure member to a state of being separated or pressed against the fixing member;
A temperature-sensitive heat storage member that is provided in contact with the inner peripheral surface of the fixing member while sliding, and generates heat by electromagnetic induction of the magnetic field to heat the fixing member;
A heating member that is provided in contact with the inside of the temperature-sensitive heat storage member and generates heat by supplying power to heat the temperature-sensitive heat storage member;
A heat storage member that is provided inside the heating member and stores heat;
An output unit that outputs the surface temperature of the fixing member detected by the temperature detection unit;
A magnetic field generating means supplied based on the surface temperature of the fixing member output by the output unit and an acquisition unit for receiving the power of the heating member;
With
It is characterized by that.

According to a fourth aspect of the present invention, in the fixing device according to the third aspect,
The heating member heats the temperature-sensitive heat storage member by Joule heat generated by power supply;
It is characterized by that.

According to the first aspect of the invention, the recovery time can be shortened and the power consumption can be reduced.
According to the second aspect of the present invention, electric power can be supplied to the magnetic field generating means and the heating member without exceeding the electric power allocated to the fixing device.
According to the invention described in claim 3, the recovery time can be shortened and the power consumption can be reduced.
According to invention of Claim 4, the temperature rise of a temperature-sensitive heat storage member can be accelerated compared with the case where it does not have this structure.

1 is a schematic cross-sectional view illustrating an internal configuration of an image forming apparatus according to an embodiment. FIG. 2 is a schematic cross-sectional view of a fixing device according to the present embodiment. FIG. 6 is a schematic front view of the fixing device according to the present embodiment as viewed from the paper carry-in side. FIG. 3 is a cross-sectional layer configuration diagram of a fixing belt constituting the fixing device. (A) is a schematic diagram for explaining the operation of the temperature-sensitive magnetic member when the temperature of the fixing belt is equal to or lower than the magnetic permeability change start temperature, and (b) is a diagram illustrating the temperature of the fixing belt indicating the magnetic permeability change start temperature. It is a schematic diagram explaining the effect | action of the temperature-sensitive heat storage member in the state of exceeding. 3 is a block diagram illustrating a power control unit of the image forming apparatus according to the present exemplary embodiment. FIG. (A) is a graph comparing the temperature changes of the fixing belts of the fixing device according to the present embodiment and the fixing device of the comparative example, and (b) is a schematic diagram of power supplied to the image forming apparatus according to the present embodiment. c) is a schematic diagram of power supplied to an image forming apparatus of a comparative example. (A) is a graph of the temperature change and supply power of the fixing belt of the fixing device of the comparative example, and (b) is a graph of the temperature change and supply power of the fixing belt of the fixing device according to this embodiment. It is a plane schematic diagram which shows an example of the external appearance of a heating member. It is a cross-sectional schematic diagram of a fixing device of a comparative example.

Next, the present invention will be described in more detail with reference to the drawings with reference to embodiments and specific examples. However, the present invention is not limited to these embodiments and specific examples.
Also, in the description using the following drawings, it should be noted that the drawings are schematic and the ratio of each dimension and the like are different from the actual ones, and are necessary for the description for easy understanding. Illustrations other than the members are omitted as appropriate.
In order to facilitate understanding of the following description, in the drawings, the front-rear direction is the X-axis direction, the left-right direction is the Y-axis direction, and the up-down direction is the Z-axis direction.

(1) Overall Configuration and Operation of Image Forming Apparatus FIG. 1 is a schematic cross-sectional view showing the internal configuration of the image forming apparatus 1 according to this embodiment.
Hereinafter, the overall configuration and operation of the image forming apparatus 1 will be described with reference to the drawings.

  The image forming apparatus 1 includes a control device 10, a paper feeding device 20, a photosensitive unit 30, a developing device 40, a transfer device 50, and a fixing device 60. On the upper surface (Z direction) of the image forming apparatus 1, a discharge tray 1a for discharging and storing a sheet on which an image is recorded is formed.

The control device 10 includes a controller 11 that controls the operation of the image forming apparatus 1, an image processing unit 12 that is controlled by the controller 11, a power supply device 13, and the like. The power supply device 13 applies a voltage to a charging roller 32, a developing roller 42, a primary transfer roller 52, a secondary transfer roller 53, and the like which will be described later.
The image processing unit 12 converts print information input from an external information transmission apparatus (for example, a personal computer) into image information for forming a latent image, and outputs a drive signal to the exposure apparatus LH at a preset timing. To do. The exposure apparatus LH of the present embodiment is configured by an LED head in which LEDs (Light Emitting Diodes) are arranged in a line.

  A paper feeding device 20 is provided at the bottom of the image forming apparatus 1. The sheet feeding device 20 includes a sheet stacking plate 21, and a plurality of sheets P as recording media are stacked on the upper surface of the sheet stacking plate 21. The paper P loaded on the paper stacking plate 21 and whose position in the width direction is determined by a regulating plate (not shown) is pulled out one by one from the top by the paper pulling unit 22 (−X direction), and then registered. It is conveyed to the nip portion of the pair 23.

  The photoconductor unit 30 includes a photoconductor drum 31 that is provided in parallel above the paper feeding device 20 (in the Z direction) and serves as an image carrier that is rotationally driven. A charging roller 32, an exposure device LH, a developing device 40, a primary transfer roller 52, and a cleaning blade 34 are arranged along the rotation direction of the photosensitive drum 31. A cleaning roller 33 for cleaning the surface of the charging roller 32 is disposed opposite to and in contact with the charging roller 32.

The developing device 40 includes a developing housing 41 in which a developer is accommodated. In the developing housing 41, a developing roller 42 disposed to face the photosensitive drum 31, and a pair of augers 44 that stir and convey the developer to the developing roller 42 side obliquely below the back side of the developing roller 42, 45 is arranged. A layer regulating member 46 that regulates the layer thickness of the developer is disposed in proximity to the developing roller 42.
Each of the developing devices 40 is configured in substantially the same manner except for the developer contained in the developing housing 41, and each forms a toner image of yellow (Y), magenta (M), cyan (C), and black (K). To do.

  The surface of the rotating photosensitive drum 31 is charged by the charging roller 32, and an electrostatic latent image is formed by the latent image forming light emitted from the exposure device LH. The electrostatic latent image formed on the photosensitive drum 31 is developed as a toner image by the developing roller 42.

The transfer device 50 includes an intermediate transfer belt 51 to which each color toner image formed on the photoconductive drum 31 of each photoconductor unit 30 is transferred, and each color toner image formed on each photoconductor unit 30 to the intermediate transfer belt. A primary transfer roller 52 that sequentially transfers (primary transfer) to 51 is provided. Further, the image forming apparatus includes a secondary transfer roller 53 that collectively transfers (secondary transfer) each color toner image superimposed and transferred onto the intermediate transfer belt 51 onto a sheet P as a recording medium.

Each color toner image formed on the photosensitive drum 31 of each photosensitive unit 30 is sequentially transferred onto the intermediate transfer belt 51 by the primary transfer roller 52 to which a predetermined transfer voltage is applied from the power supply device 13 or the like controlled by the controller 11. Electrostatic transfer (primary transfer) is performed to form a superimposed toner image in which toners of respective colors are superimposed.
The superimposed toner image on the intermediate transfer belt 51 is conveyed to a region (secondary transfer portion T) where the secondary transfer roller 53 is disposed as the intermediate transfer belt 51 moves. When the superimposed toner image is conveyed to the secondary transfer unit T, the paper P is supplied from the paper feeding device 20 to the secondary transfer unit T in accordance with the timing. A predetermined transfer voltage is applied to the secondary transfer roller 53 from the power supply device 13 or the like controlled by the controller 11, and the intermediate transfer belt 51 is fed to the sheet P fed from the registration roller pair 23 and guided by the conveyance guide. The upper multiple toner images are collectively transferred.

Residual toner on the surface of the photosensitive drum 31 is removed by the cleaning blade 34 and collected in a waste toner container (not shown). The surface of the photosensitive drum 31 is recharged by the charging roller 32. Residues that cannot be completely removed by the cleaning blade 34 and adhere to the charging roller 32 are captured and accumulated on the surface of the cleaning roller 33 that rotates in contact with the charging roller 32.

The fixing device 60 includes an endless fixing belt 61 that rotates in one direction, and a pressure roller 62 that contacts the peripheral surface of the fixing belt 61 and rotates in one direction. A nip portion N (fixing region) is formed by the pressure contact region.
The sheet P on which the toner image is transferred in the transfer device 50 is conveyed to the fixing device 60 via the conveyance guide in a state where the toner image is not fixed. The toner image is fixed on the sheet P conveyed to the fixing device 60 by a pair of fixing belt 61 and pressure roller 62 by the action of pressure bonding and heating. The sheet P on which the fixed toner image is formed is guided by a conveyance guide and is discharged from a discharge roller pair 69 to a discharge tray 1 a on the upper surface of the image forming apparatus 1.

(2) Configuration of Fixing Device FIG. 2 is a schematic cross-sectional view of the fixing device 60 constituting the fixing unit of the image forming apparatus 1 according to the present embodiment. FIG. 3 is a schematic front view of the fixing device 60 as viewed from the paper carry-in side.
The fixing device 60 includes an IH (Induction Heating) heater 80 as an example of a magnetic field generation member that generates an alternating magnetic field, a fixing belt 61 as an example of a fixing member that is electromagnetically heated by the IH heater 80 and fixes a toner image, and fixing. And a pressure roller 62 as an example of a pressure member disposed so as to face the belt 61.

As an example of a support member that supports components such as a pressure pad 63 and a pressure pad 63 that are pressed from the pressure roller 62 via the fixing belt 61 to form the nip portion N on the inner peripheral side of the fixing belt 61. A heat transfer section 64 that generates heat by electromagnetic induction by the action of an alternating magnetic field generated by the holder 65 and the IH heater 80.

At both ends of the fixing belt 61, drive transmission members 67 for transmitting the rotational driving force are provided for rotationally driving the fixing belt 61.
Further, a separation assisting member 70 that assists the separation of the sheet P from the fixing belt 61 is provided on the downstream side in the conveyance direction of the sheet P of the nip portion N between the fixing belt 61 and the pressure roller 62.

(2.1) Fixing Belt FIG. 4 is a cross-sectional layer configuration diagram of the fixing belt 61 constituting the fixing device 60 according to the present embodiment. Hereinafter, the fixing belt 61 will be described with reference to FIGS.
The fixing belt 61 is formed of an endless belt member having an original cylindrical shape, and has a diameter of 20 mm to 50 mm and a length in the width direction of 370 mm when the original shape (cylindrical shape) is used, for example. The fixing belt 61 includes a base material layer 611, a conductive heat generating layer 612 laminated on the base material layer 611, an elastic layer 613 for improving the fixability of the toner image, and a surface release layer 614 coated on the uppermost layer. A belt member having a multilayer structure.

The base material layer 611 is composed of a heat-resistant sheet-like member that supports the thin conductive heat generating layer 612 and forms the mechanical strength of the fixing belt 61 as a whole. In addition, the base material layer 611 is made of a material having a physical property (relative magnetic permeability, specific resistance) that allows the magnetic field to pass therethrough so that the AC magnetic field generated by the IH heater 80 acts up to the temperature-sensitive heat storage member 641 and the thickness. Formed with. On the other hand, the base material layer 611 itself is configured not to generate heat or hardly generate heat due to the action of a magnetic field.
Specifically, as the base material layer 611, for example, a nonmagnetic metal such as nonmagnetic stainless steel having a thickness of 30 μm to 200 μm (preferably 50 μm to 150 μm), a resin material having a thickness of 50 μm to 200 μm, or the like (for example, polyimide resin) ) Is used.

The conductive heating layer 612 is an example of a conductive layer, and is an electromagnetic induction heating element layer that is electromagnetically heated by an AC magnetic field generated by the IH heater 80. The AC magnetic field from the IH heater 80 is increased in the thickness direction. It is a layer that generates eddy current by passing through.
The frequency of the alternating magnetic field generated by the IH heater 80 is, for example, the frequency of the alternating current generated by a general general-purpose power source, that is, 20 kHz to 100 kHz. Therefore, the conductive heating layer 612 has an alternating magnetic field having a frequency of 20 kHz to 100 kHz. Is configured to penetrate and pass.

The region where the alternating magnetic field can enter the conductive heating layer 612 is defined as “skin depth (δ)”, which is a region where the alternating magnetic field attenuates to 1 / e, and is derived from the following equation (1). In the equation (1), f is the frequency of the alternating magnetic field (for example, 20 kHz), ρ is the specific resistance (Ω · m), and μr is the relative permeability.
δ = 503 (ρ / (f × μr)) ^1/2 (1)
Therefore, the thickness of the conductive heat generating layer 612 is determined by the skin depth (δ) of the conductive heat generating layer 612 defined by the equation (1) such that an alternating magnetic field having a frequency of 20 k to 100 kHz penetrates and passes through the conductive heat generating layer 612. It is configured in a thinner layer. Further, as a material constituting the conductive heat generating layer 612, for example, metals such as Au, Ag, Al, Cu, Zn, Sn, Pb, Bi, Be, and Sb, and metal alloys thereof are used.
Specifically, a nonmagnetic metal such as Cu (having a relative permeability of about 1) having a thickness of 2 μm to 20 μm and a specific resistance of 2.7 × 10 ⁻⁸ Ω · m or less is used as the conductive heat generating layer 612.
Also, from the viewpoint of shortening the time required for the fixing belt 61 to be heated to the fixing set temperature (hereinafter, referred to as “warm-up time”), the conductive heat generating layer 612 is preferably configured as a thin layer. .

The elastic layer 613 is composed of a heat-resistant elastic body such as silicone rubber. The toner image held on the sheet P to be fixed is formed by laminating each color toner as powder. Therefore, in order to supply heat uniformly to the entire toner image at the nip portion N, it is preferable that the surface of the fixing belt 61 is deformed following the unevenness of the toner image on the paper P. Therefore, for example, a silicone rubber having a thickness of 100 μm to 600 μm and a hardness of 10 ° to 30 ° (JIS-A) is suitable for the elastic layer 613.

The surface release layer 614 is provided to weaken the adhesive force with the toner melted on the paper P so that the paper P can be easily peeled from the fixing belt 61. For example, PFA (tetrafluoroethylene perfluoroalkyl vinyl ether polymer), PTFE (polytetrafluoroethylene), silicone copolymer, or a composite layer thereof is used. The thickness of the surface release layer 614 is preferably 1 μm to 50 μm in consideration of the balance between wear resistance and heat capacity.

(2.2) Pressure roller The pressure roller 62 includes, for example, a metal cylindrical core material 621 and a heat-resistant elastic body layer 622 (for example, a silicone rubber layer or the like) coated on the outer peripheral surface of the core material 621. And a release layer 623 made of a heat-resistant resin coating such as PFA or a heat-resistant rubber coating, if necessary.
The pressure roller 62 is arranged to be pressed against the pressing pad 63 via the fixing belt 61 by the moving mechanism 200 to form the nip portion N. Further, the moving mechanism 200 supports the outer peripheral surface of the fixing belt 61 so as to be able to contact and separate. During the fixing operation, the sheet P rotates in the direction of arrow B in FIG. 2, and the sheet P holding the unfixed toner image is passed through the nip N, whereby heat and pressure are applied to fix the unfixed toner image on the sheet P.

(2.3) The pressing pad and the holder pressing pad 63 are arranged in a state of being pressed from the pressure roller 62 via the fixing belt 61, and form a nip portion N with the pressure roller 62.
If the pressing pad 63 is a material in which the bending amount when combined with the holder 65 when receiving the pressing force from the pressure roller 62 is less than an allowable value, specifically, the bending amount is 0.5 mm or less. There is no restriction | limiting, For example, heat resistant resins, such as elastic bodies, such as a silicone rubber etc. and fluororubber, glass fiber reinforcement | strengthened PPS (polyphenylene sulfide), a phenol, a polyimide, a liquid crystal polymer, etc. can be used.

The holder 65 that supports the pressing pad 63 includes a holder main body 65a, and a spring member 65b that supports a temperature-sensitive heat storage member 641, a heating member 642, and a heat storage member 643 that form the heat transfer section 64, and a nip portion. The uniformity of the pressure (nip pressure) in the longitudinal direction at N is maintained. Furthermore, since the fixing device 60 of the present embodiment employs a configuration in which the fixing belt 61 is heated using electromagnetic induction, the holder main body 65a is made of a material that does not affect or hardly gives an induction magnetic field. It is made of a material that is not affected or hardly affected by the induced magnetic field. For example, a heat resistant resin such as glass fiber reinforced PPS (polyphenylene sulfide) or a nonmagnetic metal material such as Al, Cu, or Ag is used.

The pressing pad 63 includes a pre-nip region 63a on the inlet side of the nip portion N (upstream side in the conveyance direction of the paper P) and a peeling nip region 63b on the outlet side of the nip portion N (downstream side in the conveyance direction of the paper P). Different nip pressures are set.
That is, in the pre-nip region 63a, the surface on the pressure roller 62 side is formed in an arc shape that substantially follows the outer peripheral surface of the pressure roller 62, thereby forming a uniform and wide nip portion N. Further, the peeling nip region 63b is formed so as to be locally pressed from the surface of the pressure roller 62 with a large nip pressure so that the radius of curvature of the fixing belt 61 passing through the peeling nip region 63b becomes small.
As a result, a curl in a direction away from the surface of the fixing belt 61 is formed on the paper P passing through the peeling nip region 63b to promote the peeling of the paper P from the surface of the fixing belt 61.

(2.4) Peeling Auxiliary Means In this embodiment, the peeling auxiliary member 70 is disposed on the downstream side of the nip portion N as a peeling auxiliary means by the pressing pad 63. The peeling assisting member 70 is supported by the support plate 72 in a state where the peeling baffle 71 is close to the fixing belt 61 in a direction opposite to the rotational movement direction of the fixing belt 61. The curled portion formed on the paper P at the outlet of the pressing pad 63 is supported by the peeling baffle 71, thereby suppressing the paper P from moving toward the fixing belt 61.

(2.5) Driving Device of Fixing Device Next, the driving mechanism of the pressure roller 62 and the fixing belt 61 in the fixing device 60 of the present embodiment will be described with reference to FIG.
The pressure roller 62 is supported by a moving mechanism 200 that moves to move away from the fixing belt 61 when the fixing roller 61 is not pressed, thereby forming a nip portion N by pressing against the outer peripheral surface of the fixing belt 61. Yes.

During standby before the fixing operation, the pressure roller 62 is placed at a warm-up position separated from the fixing belt 61 by the moving mechanism 200, and the pressure roller 62 is not in physical contact with the fixing belt 61 (latch OFF). become.

As shown in FIG. 3, in the fixing device 60, a rotational driving force from a drive motor 90 as an example of a drive unit is transmitted between a transmission gear 92 fixed to a rotary shaft 91 and transmission gears 93, 94, 95, and 96. And the pressure roller 62 is driven to rotate.
Further, the rotational driving force from the drive motor 90 is transmitted to the shaft 103 via a transmission gear 101 fixed coaxially to the transmission gear 92 on the rotation shaft 91 and a one-way clutch 102 as an example of a rotation transmission limiting member, The transmission gears 104 and 105 coupled to the shaft 103 are transmitted to the gear portions 67b of the drive transmission members 67 disposed at both axial ends of the fixing belt 61, and the fixing belt 61 is rotationally driven.

Next, during the fixing operation, the fixing device 60 is placed in a state where the pressure roller 62 is in pressure contact with the fixing belt 61 (latch ON) by the moving mechanism 200. At this time, the one-way clutch 102 is operated, and the transmission of the rotational driving force from the drive motor 90 to the shaft 97 is stopped. The fixing belt 61 is driven to rotate by driving the pressure roller 62 to rotate.

(2.6) IH Heater Next, an IH heater 80 that performs electromagnetic induction heating by applying an AC magnetic field to the conductive heat generating layer 612 of the fixing belt 61 will be described with reference to FIG.
As shown in FIG. 2, the IH heater 80 is configured to follow the outer peripheral surface of the fixing belt 61, and is disposed so as to face the heat transfer section 64 with the fixing belt 61 interposed therebetween.

The IH heater 80 includes, for example, a support 81 made of a nonmagnetic material such as a heat resistant resin, an excitation coil 82 that generates an alternating magnetic field, an elastic support member 83 that fixes the excitation coil 82 on the support 81, and a fixing belt 61. And a magnetic core 84 that forms a magnetic path of an alternating magnetic field generated by the exciting coil 82.
Furthermore, a shield 85 that shields the magnetic field, a pressure member 86 that pressurizes the magnetic core 84 toward the support 81, and an excitation circuit 88 that supplies an alternating current (electric power) to the excitation coil 82 are provided.

The support 81 is formed so that the cross section thereof follows the outer peripheral surface of the fixing belt 61 and maintains a predetermined gap (for example, 0.5 mm to 2 mm) with the outer peripheral surface of the fixing belt 61.
Examples of the material constituting the support 81 include heat-resistant glass, PC (polycarbonate), PES (polyethersulfone), PPS (polyphenylene sulfide), or a heat-resistant resin in which glass fibers are mixed. A non-magnetic material having heat resistance such as the above is used.

The exciting coil 82 is configured by winding, for example, 90 litz wires, which are bundled with, for example, 90 copper wires having a diameter of 0.17 mm and wound in a closed loop with a hollow shape such as an ellipse, an ellipse, or a rectangle. . Then, when an alternating current of 20 k to 100 kHz generated by a general-purpose power supply is supplied from the excitation circuit 88 to the excitation coil 82, an alternating magnetic field is generated around the excitation coil 82.

The elastic support member 83 is a sheet-like member made of an elastic material such as silicone rubber or fluorine rubber, for example, and presses the excitation coil 82 against the support 81, and the excitation coil 82 supports the support surface of the support 81. It is set to be fixed in close contact with 81a.

The magnetic core 84 induces a magnetic field line (magnetic flux) generated by the alternating magnetic field generated by the exciting coil 82, crosses the fixing belt 61 from the magnetic core 84 toward the temperature-sensitive heat storage member 641, and moves inside the temperature-sensitive heat storage member 641. A path of magnetic lines of force (magnetic path) is formed so as to pass through and return to the magnetic core 84. As a result, the magnetic field lines of the alternating magnetic field generated by the exciting coil 82 are concentrated in a region facing the magnetic core 84 of the fixing belt 61.

The magnetic core 84 is desirably used in a form that reduces eddy current loss (current path interruption or division by slits, thin plate bundling, etc.), and is preferably formed of a material having low hysteresis loss. Specifically, for example, an arc-shaped ferromagnetic material composed of a high permeability oxide or alloy material such as sintered ferrite, ferrite resin, amorphous alloy (amorphous alloy), permalloy, temperature-sensitive magnetic alloy, etc. Used.

The length of the magnetic core 84 along the rotation direction of the fixing belt 61 is configured to be smaller than the length of the temperature heat storage member 641 along the rotation direction of the fixing belt 61. Thereby, the leakage of magnetic lines of force to the periphery of the IH heater 80 is reduced, and the power factor is improved. Furthermore, electromagnetic induction to the metal member constituting the fixing unit is suppressed, and the heat generation efficiency in the fixing belt 61 (conductive heat generation layer 612) is increased.

(2.7) Heat transfer portion The heat transfer portion 64 is configured to move the temperature-sensitive heat storage member 641, the heating member 642, and the heat storage member 643 from the inner peripheral surface side of the fixing belt 61 toward the central axis O1 of the fixing belt 61. It is laminated in order. The heat transfer section 64 is disposed in contact with the inner peripheral surface of the fixing belt 61 without being pressed while the fixing belt 61 is maintained in a cylindrical shape without contact with the holder main body 65a by the spring member 65b of the holder 65. .

The temperature-sensitive heat storage member 641 is formed in an arc shape (arc-shaped portion) that follows the inner peripheral surface of the fixing belt 61, contacts the inner peripheral surface of the fixing belt 61, and faces the IH heater 80 via the fixing belt 61. Arranged.

Further, the temperature-sensitive heat storage member 641 has a “permeability change start temperature” (see later), which is a temperature at which the magnetic permeability of the magnetic characteristics changes suddenly, is equal to or higher than the fixing set temperature, and the elastic layer 613 and the surface of the fixing belt 61. It is made of a material set within a temperature range lower than the heat resistant temperature of the release layer 614.
Therefore, in the temperature range below the magnetic permeability change start temperature exhibiting ferromagnetism, the magnetic field lines generated by the IH heater 80 pass through the inside of the temperature-sensitive heat storage member 641 along the shape of the temperature-sensitive heat storage member 641. A path is formed (see FIG. 5A).
On the other hand, in the temperature range exceeding the permeability change start temperature, the magnetic field lines generated by the IH heater 80 are transmitted so as to cross the thickness direction of the temperature-sensitive heat storage member 641 and pass through the heat storage member 643. A magnetic path returning to the IH heater 80 is formed (see FIG. 5B).
The “permeability change start temperature” here is a temperature at which the permeability (for example, the permeability measured by JIS C2531) starts to decrease continuously, and is the Curie point at which the magnetism disappears. However, it has a different concept from the Curie point.

Specifically, the material used for the temperature-sensitive heat storage member 641 is, for example, an Fe—Ni alloy (permalloy) in which the magnetic permeability change start temperature is set within a fixing set temperature (eg, 140 ° C. to 240 ° C.). Binary temperature-sensitive magnetic alloys such as ternary temperature-sensitive magnetic alloys such as Fe-Ni-Cr alloys are used. Such metal alloys such as permalloy and temperature-sensitive magnetic alloy are suitable for the temperature-sensitive heat storage member 641 because they are excellent in moldability and workability, have high heat conductivity, and are inexpensive. As other materials, a metal alloy made of Fe, Ni, Si, B, Nb, Cu, Zr, Co, Cr, V, Mn, Mo or the like is used.
Further, the temperature-sensitive heat storage member 641 is formed with a thickness larger than the skin depth δ (see the above formula (1)) with respect to the AC magnetic field (lines of magnetic force) generated by the IH heater 80. Specifically, for example, when an Fe—Ni alloy is used, the thickness is set to about 50 μm to 300 μm.

FIG. 9 shows an example of the appearance of the heating member 642.
The heating member 642 includes two electrodes 642a and 642c, a resistance member 642b that connects the two electrodes, and two insulating sheets 642d that sandwich the resistance member 642b from both sides.
Specifically, for example, the resistance member 642b can be made of stainless steel having a thickness of 30 μm. The two insulating sheets 642d have thermal conductivity and electrical insulation, for example, a PET (polyethylene terephthalate) sheet laminated with a thin layer such as PP (polypropylene) or PE (polyethylene), or PI (polyimide). A film or the like can be used, and each has a thickness of 25 μm to 50 μm.

The electrodes 642a and 642c are made of a metal such as Ag, Al, Cu, or Ni. Here, a copper plate is used as a base material and is bonded and fixed to the resistance member 642b using a silver paste. A current-carrying wiring (not shown) is connected to the electrodes 642a and 642c. When the current is passed between the pair of electrodes 642a and 642c, the resistance member 642b generates heat (Joule heat) and is sensed through the insulating sheet 642d. The heat storage member 641 is heated.

The heat storage member 643 is arranged with the heating member 642 between the inner peripheral surface of the temperature-sensitive heat storage member 641.
The heat storage member 643 has a larger heat capacity than the fixing belt 61 and the heating member 642, and stores heat generated by the fixing belt 61 and the temperature-sensitive heat storage member 641. Therefore, the heat storage member 643 is made of a nonmagnetic metal having a relatively small specific resistance value such as Ag, Cu, or Al.
When the temperature-sensitive heat storage member 641 rises to a temperature equal to or higher than the permeability change start temperature, an alternating magnetic field (line of magnetic force) generated by the IH heater 80 is induced, and the vortex is more vortexed than the conductive heating layer 612 of the fixing belt 61. A state in which the current I is easily generated is formed. Therefore, the heat storage member 643 is formed with a predetermined thickness (for example, 1.0 mm) sufficiently thicker than the skin depth δ (see the above formula (1)) so that the eddy current I can easily flow. .

(3) Actions and Effects of Fixing Device and Image Forming Apparatus (3.1) Operation of Fixing Device Next, operations of the fixing device 60 and the image forming apparatus 1 according to the present embodiment will be described.
First, in the fixing device 60, for example, a toner image forming operation in the image forming apparatus 1 is started, and the driving transmission member 67 is driven by the driving motor 90 in a state where the fixing belt 61 and the pressure roller 62 are separated (latch OFF). , And the fixing belt 61 is driven to rotate (see arrow A in FIG. 2).

The fixing belt 61 is driven to rotate, and an alternating current is supplied from the excitation circuit 88 to the excitation coil 82 constituting the IH heater 80. When an alternating current is supplied to the exciting coil 82, a magnetic flux (magnetic field) repeatedly generates and disappears around the exciting coil 82. When this magnetic flux (magnetic field) crosses the temperature-sensitive heat storage member 641, an eddy current is generated in the temperature-sensitive heat storage member 641 so as to generate a magnetic field that hinders the change in the magnetic field, and the skin resistance and temperature sensitivity of the temperature-sensitive heat storage member 641. Heat is generated in proportion to the square of the magnitude of the current flowing through the heat storage member 641.
Further, the temperature-sensitive heat storage member 641 and the heat storage member 643 are heated via the insulating sheet 642d by the resistance member 642b of the heating member 642 being energized between the pair of electrodes 642a and 642c.

Here, in order to heat the image forming apparatus to a predetermined fixing set temperature (T1) within a desired short warm-up time, the excitation that constitutes the IH heater 80 from the excitation circuit 88 when the fixing apparatus 60 starts up. It is necessary to supply large electric power to the coil 82.
However, the allowable maximum power amount for starting up the fixing device 60 is determined from the rated power of the image forming apparatus, and cannot be exceeded. On the other hand, when the rated power of the image forming apparatus is changed to a large one, a problem such as requiring a special power supply work for the user occurs.

Therefore, the control device 10 instructs the excitation circuit 88 and the auxiliary power supply 89 to be energized within the range of the maximum power allocated in advance to the fixing device 60 via the power supply means (not shown in FIG. 1), and the excitation circuit 88. AC current is supplied to the exciting coil 82. Further, an alternating current is supplied from the auxiliary power source 89 to the heating member 642.

Here, the fixing belt 61 has a conductive heat generating layer 612 made of a non-magnetic metal such as Cu (relative magnetic permeability is approximately 1). The fixing belt 61 penetrates the magnetic flux (magnetic field) and transmits the magnetic flux (magnetic field). The conductive heat generating layer 612 generates heat by the action.
The temperature-sensitive heat storage member 641 heats the fixing belt 61 while being rubbed against the inner peripheral surface of the fixing belt 61. As a result, the fixing belt 61 is heated to the fixing set temperature T1 (for example, 150 ° C.) with a short rise time.

Next, in a state in which the pressure roller 62 is pressed against the fixing belt 61 (latch ON), the sheet P sent to the fixing device 60 is sent to the nip portion N between the fixing belt 61 and the pressure roller 62. The toner image is fixed on the surface of the paper P by being heated and pressed by the fixing belt 61 and the pressure roller 62 heated by the temperature-sensitive heat storage member 641.
When the sheet P is fed from the nip N between the fixing belt 61 and the pressure roller 62, the sheet P is peeled off from the surface of the fixing belt 61.

(3.2) Heating Control Method of Fixing Device Next, a heating control method of the fixing device 60 according to the present embodiment will be described with reference to the drawings.
FIG. 6 is a block diagram of a power control unit 300 as a power supply unit provided in the control device 10 (see FIG. 1) of the image forming apparatus 1.
FIG. 7A is a graph comparing the temperature change of the fixing belt of the fixing device according to the present embodiment and the fixing device of the comparative example, and FIG. 7B is the power supplied to the image forming apparatus 1 according to the present embodiment. FIG. 7C is a schematic diagram of the power supplied to the image forming apparatus 1A of the comparative example.

The fixing device 60 according to the present embodiment includes a temperature sensor 110 that is an example of a temperature detection unit facing the IH heater 80 on the inner surface of the fixing belt 61 and detects the temperature of the fixing belt 61. A rotation detector 107 which is an example of a rotation detector is provided to detect the rotation speed of the fixing belt 61.
The temperature of the fixing belt 61 detected by the temperature sensor 110 and the rotation speed of the fixing belt 61 detected by the rotation detector 107 are output from the temperature / rotation speed output unit 901 to the power control unit 300 (see FIG. 6). The

The fixing device 60 includes a setting power acquisition unit 902 for an excitation circuit and an auxiliary power source, and the rotation number of the fixing belt 61 and the temperature of the fixing belt 61 output from the power control unit 300 via the temperature / rotation number output unit 901. The power supply amount of the excitation circuit and auxiliary power set based on the base is received.

Then, an alternating current is supplied from the excitation circuit 88 to the excitation coil 82. Further, an alternating current is supplied from the auxiliary power source 89 to the heating member 642. The excitation circuit 88 and the auxiliary power supply 89 may be supplied with power from a common power source (not shown) via the power control unit 300, or may be supplied with power from different power sources.

The power control unit 300 detects the surface temperature of the fixing belt 61 based on the amount of electricity sent from the temperature sensor 110, and compares the detected temperature with a preset fixing temperature (T1) stored in advance, while exciting the circuit. 88 and the auxiliary power supply 89 are driven or stopped, and heating control of the fixing belt 61 is performed when the fixing device 60 is started up and during fixing processing.

In the fixing device 60, the excitation circuit is operated by the power control unit 300 during an elapse time (t 2) from the start of image formation of the image forming device 1 until the measured temperature of the fixing belt 61 reaches the fixing setting temperature T 1. Both 88 and auxiliary power supply 89 are driven.
When the measured temperature of the fixing belt 61 is higher than the fixing set temperature (T1), the driving of the auxiliary power supply 89 is stopped, and the preset supply power (P1) is supplied from the excitation circuit 88 to the excitation coil 82. Is done.

In the fixing device 60, the pressure roller 62 is separated from the surface of the fixing belt 61 until the temperature of the surface of the fixing belt 61 reaches the fixing setting temperature T1.
When the surface temperature of the fixing belt 61 reaches the fixing set temperature (T1), the pressure roller 62 is placed in pressure contact with the fixing belt 61 (latch ON) by the moving mechanism 200. At this time, the one-way clutch 102 is operated, and the transmission of the rotational driving force from the drive motor 90 to the shaft 97 is stopped. Then, the pressure roller 62 starts to rotate in the arrow B direction, and the fixing belt 61 is driven to rotate in the arrow A direction.

(3.3) Operation of Fixing Device and Image Forming Apparatus Here, the temperature and supply power of the fixing belt 61 when starting up in the fixing device 60 of the present embodiment will be described in comparison with a comparative example.
FIG. 10 shows a fixing device 60A as a comparative example. In the fixing device 60A of the comparative example, the heat transfer section 64A is formed by laminating the temperature-sensitive heat storage member 641 and the heat storage member 643 in this order from the inner peripheral surface side of the fixing belt 61 toward the central axis O1 of the fixing belt 61. The difference is that the heating member 642 is not provided.
In the image forming apparatus 1 </ b> A including the fixing device 60 </ b> A, the power control unit 300 </ b> A as a power supply unit controls only the power supplied to the excitation coil 82 of the IH heater 80.
Therefore, the same components as those in the image forming apparatus 1 and the fixing device 60 according to the present embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

"Comparative example"
Here, in the fixing device 60 </ b> A, when the control device 10 instructs the excitation circuit 88 to energize within the range of the maximum power allocated to the fixing device 60 in advance, an alternating current is supplied from the excitation circuit 88 to the excitation coil 82. A magnetic field is generated around the exciting coil 82. Due to the electromagnetic induction of the magnetic field, the fixing belt 61 and the temperature-sensitive heat storage member 641 generate heat, and the fixing belt 61 is heated.

In FIG. 7A, the temperature change of the fixing belt of the fixing device 60A of the comparative example is indicated by G0.
FIG. 7C is a schematic diagram of power supplied to the image forming apparatus 1A of the comparative example.
The control device 10 detects the surface temperature of the fixing belt 61 based on the amount of electricity sent from the temperature sensor 110, and until the detected temperature reaches a predetermined fixing set temperature (T1), the fixing device 60. Power is supplied from the excitation circuit 88 to the excitation coil 82 within the range of the maximum power allocated in advance (P0) (see FIG. 7C).

When the temperature detected by the temperature sensor 110 reaches a predetermined fixing set temperature (T1), the control device 10 causes the pressure roller 62 to be pressed against the fixing belt 61 (latched ON) by the moving mechanism 200. At this time, the one-way clutch 102 is operated, and the transmission of the rotational driving force from the drive motor 90 to the shaft 97 is stopped. Then, the pressure roller 62 starts to rotate in the arrow B direction, and the fixing belt 61 is driven to rotate in the arrow A direction.

Although the temperature of the surface of the fixing belt 61 temporarily decreases due to contact with the pressure roller 62, the control device 10 detects the surface temperature of the fixing belt 61 based on the amount of electricity sent from the temperature sensor 110, Again, until this detected temperature reaches a predetermined fixing set temperature (T1), power is continuously supplied to the exciting coil 82 within the maximum power range (P0), and the fixing belt 61 is heated.

Then, when the surface temperature of the fixing belt 61 reaches a predetermined fixing set temperature (T1) (t3), the supply power (P0) supplied to the exciting coil 82 is changed to a preset supply power (P3). ) To perform fixing processing. As a result, the warm-up time becomes longer until the time (t3) when the surface temperature of the fixing belt 61 reaches the predetermined fixing set temperature (T1) again.

In the fixing device 60 </ b> A of the comparative example, the heat transfer section 64 </ b> A does not include the heating member 642 between the temperature-sensitive heat storage member 641 and the heat storage member 643. Therefore, the heat-sensitive heat storage member 641 is heated by electromagnetic induction, but has a larger heat capacity than the fixing belt 61, and the fixing is performed at the time (t1) when the surface temperature of the fixing belt 61 reaches the fixing set temperature (T1). The surface temperature of the belt has not been reached.

In this state, when the pressure roller 62 is brought into pressure contact (latching ON) with the fixing belt 61, a part of the heat amount of the fixing belt 61 is absorbed by the pressure roller 62, but the absorbed heat amount is absorbed by the temperature-sensitive heat storage member. The amount of heat stored in 641 cannot be supplemented.
Therefore, the control device 10 continues within the range of the maximum power (P0) preliminarily allocated to the fixing device 60A until the surface temperature of the fixing belt 61 reaches the preset fixing temperature (T1). Electric power is supplied to the exciting coil 82 to heat the fixing belt 61.

As a result, in the fixing device 60A of the comparative example, the warm-up time becomes long (t3), and during that time, the excitation circuit 88 is supplied with the maximum power (P0) assigned in advance. Become more.

"This embodiment"
In FIG. 7A, the temperature change of the fixing belt of the fixing device 60 according to this embodiment is indicated by G1.
FIG. 7B is a schematic diagram of power supplied to the image forming apparatus 1 according to the present embodiment.
The power control unit 300 detects the surface temperature of the fixing belt 61 based on the amount of electricity sent from the temperature sensor 110, and until the detected temperature reaches a predetermined fixing set temperature (T1). Is energized to the excitation circuit 88 and the auxiliary power supply 89 within the range of the maximum power (P0) allocated in advance. Then, the first power (P1) is supplied from the excitation circuit 88 to the excitation coil 82, and the second power (P2) is supplied from the auxiliary power source 89 to the heating member 642 (see FIG. 7B). .
The first power (P1) supplied to the exciting coil 82 and the second power (P2) supplied to the heating member 642 are preliminarily assigned to the fixing device 60 as the total power (P1 + P2). If it is within the range of maximum power (P0), it can select suitably.

Also in the fixing device 60 according to the present embodiment, at the time of start-up, like the fixing device 60A of the comparative example, the first power (P1) supplied to the exciting coil 82 and the second power supplied to the heating member 642 are used. The electric power (P2) is supplied when the total electric power (P1 + P2) is supplied within the range of the maximum electric power (P0) allocated in advance, so that the surface temperature of the fixing belt 61 reaches the fixing set temperature (T1). (T1) does not cause a large difference with respect to the comparative example.

When the temperature detected by the temperature sensor 110 reaches a predetermined fixing set temperature (T1), the control device 10 causes the pressure roller 62 to be pressed against the fixing belt 61 (latched ON) by the moving mechanism 200.
Here, since the heat transfer section 64 of the fixing device 60 includes the heating member 642 in contact with each surface between the temperature-sensitive heat storage member 641 and the heat storage member 643, the temperature-sensitive heat storage member having a large heat capacity. 641 is heated from the heating member 642 and stored.

Therefore, when the pressure roller 62 is pressed against the fixing belt 61 (latched ON), the heat amount of the fixing belt 61 is absorbed by the pressure roller 62, and the absorbed heat amount is stored in the heat-sensitive heat storage member 641. The surface temperature of the fixing belt 61 is maintained at a preset fixing temperature (T1) or higher that is stored in advance.

Therefore, the power control unit 300 stops the power supply from the auxiliary power supply 89 to the heating member 642, and uses the power supplied from the excitation circuit 88 to the excitation coil 82 to the preset power (P1) for the fixing operation. Switch to. That is, at this time, the warm-up is completed (hereinafter referred to as RDY), and the warm-up time is shortened as compared with the fixing device 60A of the comparative example (t1 in FIG. 7A).

Accordingly, when the fixing device 60 starts up, the maximum power (already allocated to the fixing device 60) until the time (t1) when the temperature detected by the temperature sensor 110 first reaches the preset fixing temperature (T1) stored in advance. Since P0 = P1 + P2) is supplied and thereafter, the RDY state is entered, so that the power consumption at the time of start-up is reduced as compared with the fixing device 60A of the comparative example.

In the image forming apparatus 1 including the fixing device 60 of the present embodiment, the temperature-sensitive heat storage member 641 and the fixing belt 61 are heated by the first electric power (P1) supplied to the exciting coil 82 and supplied to the heating member 642. The heating member is caused to generate heat by the second electric power (P2), and the temperature-sensitive heat storage member is heated. Then, the pressure roller 62 is pressed against the fixing belt 61 (latched ON) by appropriately selecting the total power (P1 + P2) within the range of the maximum power (P0) previously assigned to the fixing device 60. At this time, the surface temperature of the fixing belt 61 can be prevented from being lowered, and the substantial warm-up time can be shortened.
As a result, power consumption when starting up the fixing device 60 can be reduced.

Hereinafter, it demonstrates in detail using an Example.
8A is a graph of temperature change and supply power of the fixing belt 61 of the fixing device 60A of the comparative example, and FIG. 8B is a temperature change and supply of the fixing belt 61 of the fixing device 60 according to the present embodiment. It is a graph of electric power.

"Comparative Example 1"
The image forming apparatus 1 shown in FIG. 1 was used as the image forming apparatus. Further, the fixing device 60A shown in FIG. 9 was used as the fixing device. Specifically, the maximum power (P0) allocated in advance of the fixing device 60A is 1100 (w).
In Comparative Example 1, the maximum power 1100 (w) was supplied to the IH heater 80 from the time when the fixing device 60A started up (0 sec), and the temperature transition of the fixing belt 61 and the temperature detected by the temperature sensor 110 were measured. .

The time (t1) at which the temperature detected by the temperature sensor 110 reached the fixing set temperature (T1) was 5.9 seconds. At this time, the pressure roller 62 is pressed against the fixing belt 61 (latched ON) by the moving mechanism 200, and the surface temperature of the fixing belt 61 is lowered. Therefore, the control device 10 finishes the warm-up completion of the fixing device 60A. The power supply to the IH heater 80 was continued.
The time when the detected temperature of the temperature sensor 110 reaches the fixing set temperature (T1) again is 9.2 seconds. At this time, the control device 10 supplies power to the IH heater 80 during a predetermined fixing operation. Switching to the supplied power (P1), the warm-up completion (RDY) of the fixing device 60A is displayed at the time of 10.6 seconds (t2).
Thereafter, the timing (t3) at which the sheet P having the toner image transferred from the image forming apparatus 1 enters the nip portion N is 12.5 seconds from the start of warm-up.

The area indicated by hatching in FIG. 8A shows the power consumption during warm-up in this comparative example 1, and was specifically 11300 joules.

"Example 1"
The image forming apparatus 1 shown in FIG. 1 was used as the image forming apparatus. Further, the fixing device 60 shown in FIG. 2 was used as the fixing device. Specifically, the maximum power (P0) allocated in advance of the fixing device 60 is 1100 (w), and when the fixing device 60A starts up (0 sec), the IH heater 80 is 600 (w), a heating member. 500 (w) was supplied to a heater as an example of 642, and the temperature transition of the fixing belt 61 and the temperature detected by the temperature sensor 110 were measured.

The time (t2) at which the temperature detected by the temperature sensor 110 reached the fixing set temperature (T1) was 7.5 seconds. At this point, the pressure roller 62 is pressed against the fixing belt 61 (latched ON) by the moving mechanism 200, but the surface temperature of the fixing belt 61 does not decrease, and the control device 10 completes the warm-up of the fixing device 60 (RDY). ) Is displayed.
The control device 10 stopped the power supply to the heater and switched the power supply to the IH heater 80 to a predetermined power (P1) during the fixing operation.
Thereafter, the timing (t3) at which the sheet P having the toner image transferred from the image forming apparatus 1 enters the nip portion N was 9.5 seconds.

The area indicated by hatching in FIG. 8B shows the power consumption during warm-up in Example 1, and was specifically 8880 Joules.

In the fixing device 60 as the first embodiment of the present invention and the image forming apparatus 1 having the same within the range of the allowable maximum electric energy, the warm-up time is 10.6 seconds to 7.5 with respect to the comparative example 1. Shortened to seconds.
In addition, the power consumption during warm-up could be reduced by approximately 30% from 11300 joules to 7880 joules.

The embodiments of the present invention have been described with specific examples. However, the technical scope of the present invention is not limited to the above-described embodiments, and various modifications are made without departing from the spirit of the present invention. It is possible.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus 10 ... Control apparatus 20 ... Paper feed apparatus 30 ... Photoconductor unit 40 ... Developing apparatus 50 ... Transfer apparatus 60, 60A ... Fixing apparatus 61 ... Fixing belt 611: base material layer 612 ... conductive heat generating layer 613 ... elastic layer 614 ... surface release layer 62 ... pressure roller 63 ... pressure pad 64, 64A ... Heat transfer section 641 ... Temperature sensitive heat storage member 642 ... Heating member 643 ... Heat storage member 65 ... Holder 67 ... Drive transmission member 70 ... Peeling auxiliary member 80 ... IH heater 81. ..Support 82 ... Excitation coil 84 ... Magnetic core 90 ... Drive motor 200 ... Moving mechanism 300, 300A ... Power control unit

Claims (4)

Toner image forming means for forming a toner image;
A fixing member having a conductive layer and fixing the toner to the recording medium by electromagnetically heating the conductive layer;
A pressure member that conveys the recording medium between the fixing member and the fixing member;
A magnetic field generating means disposed opposite to the fixing member to generate a magnetic field;
Driving means for rotating the pressure member by following the fixing member;
Temperature detecting means for detecting the surface temperature of the fixing member;
Moving means for moving the pressure member to a state of being separated or pressed against the fixing member;
A temperature-sensitive heat storage member that is provided in contact with the inner peripheral surface of the fixing member while sliding, and generates heat by electromagnetic induction of the magnetic field to heat the fixing member;
A heating member that is provided in contact with the inside of the temperature-sensitive heat storage member and generates heat by supplying power to heat the temperature-sensitive heat storage member;
A heat storage member that is provided inside the heating member and stores heat;
A fixing device comprising:
Power supply means for supplying power to the magnetic field generating means and the heating member;
With
An image forming apparatus. A power limit for limiting the power supplied by the power supply means within a range of preset maximum power to the sum of the first power supplied to the magnetic field generating means and the second power supplied to the heating member. With means,
The image forming apparatus according to claim 1. A fixing member having a conductive layer and fixing the toner to the recording medium by electromagnetically heating the conductive layer;
A pressure member that conveys the recording medium between the fixing member and the fixing member;
A magnetic field generating means disposed opposite to the fixing member to generate a magnetic field;
Driving means for rotating the pressure member by following the fixing member;
Moving means for moving the pressure member to a state of being separated or pressed against the fixing member;
Temperature detecting means for detecting the surface temperature of the fixing member;
Moving means for moving the pressure member to a state of being separated or pressed against the fixing member;
A temperature-sensitive heat storage member that is provided in contact with the inner peripheral surface of the fixing member while sliding, and generates heat by electromagnetic induction of the magnetic field to heat the fixing member;
A heating member that is provided in contact with the inside of the temperature-sensitive heat storage member and generates heat by supplying power to heat the temperature-sensitive heat storage member;
A heat storage member that is provided inside the heating member and stores heat;
An output unit that outputs the surface temperature of the fixing member detected by the temperature detection unit;
A magnetic field generating means supplied based on the surface temperature of the fixing member output by the output unit and an acquisition unit for receiving the power of the heating member;
With
A fixing device. The heating member heats the temperature-sensitive heat storage member by Joule heat generated by power supply;
The fixing device according to claim 3.

Images