JP5091541B2 - Fixing device and image forming apparatus using the same - Google Patents

Description

  The present invention relates to a fixing device and an image forming apparatus using the same, and more particularly to an apparatus using an electromagnetic induction heating method.

  In an image forming apparatus such as a copying machine, a printer, a facsimile machine, a printing machine, or a combination of these, an image is formed by transferring a visible image such as a toner image carried on a latent image carrier onto a recording material such as a recording sheet. Get the output. When the toner image passes through the fixing device, the toner image is fixed on the recording material by melting and permeating action due to heat and pressure. As described above, the heating method employed in the fixing device includes a heating roller using a halogen lamp or the like as a heat source and a pressure roller that is in contact with the heating roller. Although there is a film fixing method using a film that has a smaller heat capacity than the roller itself as a heating member, in recent years, a fixing method using an electromagnetic induction heating method as a heating method (for example, see Patent Document 1) has attracted attention. Yes.

  In the fixing method using the electromagnetic induction heating method disclosed in Patent Document 1, an induction heating coil wound around a bobbin is provided inside the heating roller, and an eddy current is applied to the heating roller by applying a current to the induction heating coil. Is generated, whereby the heating roller generates heat. In this configuration, there is an advantage that it is possible to instantaneously raise the temperature to a predetermined temperature without the need for residual heat unlike the heat roller fixing method.

  The fixing method using the electromagnetic induction heating method includes a high-frequency induction heating device including an induction heating coil to which a high-frequency voltage is applied from a high-frequency power source, and a heat generation layer having magnetism provided on the heating rotating body. In the heat generating layer, a fixing device is known that generates heat when a Curie point is generally set to a fixing temperature and a high frequency voltage is applied to a high frequency induction heating device by a high frequency power source (see, for example, Patent Document 2).

  In this device, the temperature of the ferromagnetic material contained in the adhesive is instantaneously increased by the high frequency induction heating device until the Curie point is reached, and when the Curie point is reached, the magnetism is lost and the temperature is further increased. Instead, a constant temperature is maintained. Since the Curie point of the ferromagnetic material is generally set at the fixing temperature, the ferromagnetic material is generally maintained at the fixing temperature. Accordingly, the rise time of the heating rotator is shortened and high accuracy is obtained without impairing the high releasability, heat resistance, etc. of the surface of the heating rotator required as a fixing device, and without requiring a complicated control device. Temperature control can be performed.

  Furthermore, the heating rotors with different thicknesses and shapes of the cored bar and the releasable resin layer have different heat capacities, but the rise time and control temperature accuracy can be improved by adjusting the content of the ferromagnetic powder. In addition, since the ferromagnetic powder loses its magnetism at the Curie point, the toner containing the magnetic powder is attracted to the heating rotator by a magnetic force and no offset or the like occurs.

Japanese Patent Laid-Open No. 2001-13805 Japanese Patent No. 2975435

  However, in the conventional fixing device of the above-described electromagnetic induction heating method, as the temperature of the magnetic heat generating layer rises, leakage magnetic flux is generated from the magnetic heat generating layer, and the temperature rise slows down just before reaching the target temperature for fixing and warms up. There is a problem that the time becomes long, and there is a conflicting problem that if the Curie point is raised in order to solve this, the target overheating function cannot be obtained.

  An object of the present invention is to provide a fixing device that satisfies both the prevention of overheating of a magnetic heat generating layer and the prevention of slowing of temperature rise, and an image forming apparatus using the same, paying attention to the above-described conventional problems.

The invention of claim 1
A heat generating rotating body having a heat generating layer that generates heat by magnetic flux;
A magnetic flux generator disposed outside the heat generating rotor and generating magnetic flux;
A magnetic shunt layer formed integrally with or separately from the heat generating layer,
An electric conductor disposed inside the magnetic shunt layer, having a volume resistance lower than that of the magnetic shunt layer, and through which the magnetic flux transmitted through the magnetic shunt layer passes,
In a fixing device for fixing an image on a recording medium by heat generation of the heat generating rotating body,
With placing a support layer constituted by a non-conductive material inside said heating layer,
The fixing device according to claim 1, wherein a contour of the conductor is circular, and a center of the circle is separated from a rotation center of the conductor .

The invention of claim 2 is the fixing device according to claim 1, characterized in that a heat insulating layer between the supporting layer and the heating layer.

According to a third aspect of the present invention, in the fixing device according to the second aspect , the heat insulating layer is formed of an elastic body.

According to a fourth aspect of the present invention, there is provided the fixing device according to any one of the first to third aspects, further comprising a drive unit that rotates the conductor independently of the heat-generating rotator.

According to a fifth aspect of the present invention, in the fixing device according to any one of the first to fourth aspects, the distance between the conductor and the magnetic shunt layer can be changed according to a set position in a rotation direction thereof.

A sixth aspect of the present invention is an image forming apparatus comprising the fixing device according to any one of the first to fifth aspects.

In the present invention, the temperature rise does not slow down immediately before reaching the target temperature for fixing, the warm-up time is not prolonged, and the target overheating function can be obtained without increasing the Curie point .

  The best mode for carrying out the present invention will be described below with reference to the embodiments shown in the drawings.

  FIG. 1 is a diagram illustrating an embodiment of an image forming apparatus to which the fixing device according to the present embodiment is applied. Of course, the present invention is not limited to the apparatus of the type shown in FIG. 1, and is intended not only for producing a single color image but also for forming a color image.

  The illustrated image forming apparatus includes an electrophotographic photosensitive member (hereinafter simply referred to as a photosensitive member) 41 which is an example of an image carrier and is a rotating member having a drum shape, and around the photosensitive member 41 in the drawing. Sequentially in the rotational direction indicated by the arrow, a charging device 42 comprising a charging roller, a mirror 43 constituting a part of the exposure means, a developing means 44 having a developing roller 44a, a sheet-like recording material P such as transfer paper, recording paper, etc. A transfer device 48 for transferring the developed image (toner image) to the photosensitive member 41, a cleaning means 46 having a blade 46a slidably contacting the peripheral surface of the photoreceptor 41, and the like are disposed. Then, between the charging device 42 and the developing roller 44a, the photoconductor 41 is scanned by exposing and exposing the exposure light Lb through the mirror 43. The irradiation position of the exposure light Lb is referred to as an exposure unit 150.

  A portion where the transfer device 48 faces the lower surface of the photoconductor 41 is a known transfer portion 47 to which a toner image is transferred to the recording material P. A pair of resists is provided upstream of the transfer portion 47 in the paper feeding direction. A roller 49 is provided. A sheet-like recording material P such as transfer paper stored in one of the paper feed trays 40 is fed to the registration rollers 49 by the rollers of the paper feed roller group 110, and includes a transport guide and a transport roller group (reference numerals). It is designed to be transported while being guided. Further, the fixing device 20 is disposed at a position downstream of the transfer unit 47 in the paper feeding direction, and on the downstream side of the fixing device 20 in the paper feeding direction, the front and back surfaces of the transfer paper are reversed when performing double-sided recording. An automatic double-sided device 39 for re-feeding the transfer unit 47 is disposed.

  Image formation in the present embodiment is generally performed as follows. First, on the upper side of the apparatus, the photosensitive member 41 starts rotating, and during this rotation, the photosensitive member 41 is uniformly charged by the charging device 42 in the dark, and the exposure unit 150 is irradiated with the exposure light Lb corresponding to the image to be created. By scanning, a latent image corresponding to the image to be created is formed on the photoreceptor 41. When the latent image approaches the developing device 44 due to the rotation of the photosensitive member 41, the latent image is visualized by the toner here and becomes a toner image carried on the photosensitive member 41. On the other hand, on the lower side of the apparatus, the recording material P is called from any one of the plurality of paper feed trays 40 by the paper feed roller group 110 of any one of the paper feed trays 40. The toner is transported to the position of the pair of registration rollers 49 through a predetermined transport path, temporarily stopped, and sent out at a timing such that the toner image on the photoreceptor 41 is opposed to the predetermined position of the recording material P by the transfer unit 47. That is, when a suitable timing arrives, the recording material P stopped at the position of the registration roller 49 is sent out by the registration roller 49 and conveyed toward the transfer unit 47.

  The toner image on the photoreceptor 41 and the predetermined position of the recording material P to which the toner image is to be transferred coincide with each other at the transfer portion 47, and the toner image is formed on the recording material P by the electric field generated by the transfer member 48. Sucked and transferred. In this way, the recording material P on which the toner image is transferred and carried by the image forming portion around the photosensitive member 41 is sent out toward the fixing device 20. Then, after the toner image on the recording material P is heated and pressurized while passing through the fixing device 20 and fixed on the recording material P, the recording material P is discharged to a paper discharge portion.

  Further, when forming an image on both sides of the recording material P, the recording material P discharged to the automatic double-side device 39 by a branching claw (not shown) is switched back by the automatic double-side device 39 and conveyed before the registration roller 49. It is transported to the route.

  Residual toner remaining on the photoconductor 41 without being transferred by the transfer unit 47 reaches the cleaning device 46 as the photoconductor 41 rotates, and is cleaned and removed from the photoconductor 41 while passing through the cleaning device 46. Thus, it becomes possible to shift to the next image formation.

  Although the details will be described later, the fixing device is configured to employ a fixing method employing a pair of rollers. For this reason, the fixing device includes a heat source for heating the fixing roller, and the pressure roller is in contact with and pressed against the fixing roller.

  FIG. 2 is a cross-sectional view showing a conceptual configuration of a roller-type fixing device that can be used in the image forming apparatus shown in FIG. In the figure, 2 is a magnetic flux generator, 3 is a fixing roller which is a heat generating rotator, 4 is a pressure roller which is a pressure rotator, P is a recording material, and T is a toner placed on the recording material P. Note that the fixing device in the illustrated example generates a high-frequency magnetic field by driving the coil 2a included in the magnetic flux generation unit 2 with a high frequency by an inverter (not shown) that is an induction heating circuit. The roller temperature is raised so that an eddy current flows through the fixing roller 3. In the figure, 2b is a foot core, 2c is a center core, 2d is an arch core, and the coil 2a is located between the arch core 2d and the fixing roller 3.

  FIG. 3 is an enlarged sectional view showing a part of the fixing roller 3. The fixing roller 3 has a diameter of 40 mm, for example, and is provided with a demagnetizing layer (core metal) 3A on the innermost side, and on the outer side, as shown by an arrow, toward the image surface side of the recording material P, a heat insulating layer 3B made of air, The magnetic shunt layer 3C, the antioxidant layer 3D1, the heat generating layer 3E, the antioxidant layer 3D2, the elastic layer 3F, and the release layer 3G as the surface layer are formed. The demagnetizing layer 3A has, for example, aluminum or an alloy thereof, and the air-insulating layer 3B has a gap of, for example, about 5 mm. The magnetic shunt layer 3C is a known and appropriate magnetic shunt alloy (eg, 50 μm thick), the antioxidant layers 3D1, 3D2 are nickel strike plated (eg, 1 μm or less in thickness), and the heat generating layer 3E is Cu plated (eg, thickness). 15 μm), silicone rubber (for example, 150 μm thick) is used for the elastic layer 3F, and PFA (30 μm thick) is used for the release layer 3G. That is, the thickness from the magnetic shunt layer 3C to the surface of the release layer 3G is, for example, 200 to 250 μm, but these are all examples.

  The magnetic shunt layer 3C is made of a magnetic material (for example, a magnetic shunt alloy material containing iron or nickel) having a Curie point of, for example, 100 to 300 ° C., and is deformed by pressing of the pressure roller 4 to form a nip. It is comprised so that it may do. The presence of the magnetic shunt layer 3C prevents overheating of the heat generating layer 3E and the like. Further, since it is easy to form a nip having a concave shape on the fixing roller 3 side, the separation of the recording material P can be excellent. Of course, what is deformed by the pressing of the pressure roller 4 is the magnetic shunt layer 3C to the release layer 3G other than the cored bar 3A in the illustrated embodiment.

  4A is a cross-sectional view of the fixing roller 3. A thick solid line arrow indicates an induced magnetic flux from the coil 2a, and a fine solid line arrow indicates an eddy current (see FIG. 4C). Since the temperature T of the magnetic shunt alloy layer constituting 3C is lower than the Curie temperature Tc, the magnetic shunt alloy constituting the magnetic shunt layer 3C remains a magnetic body, and the induced magnetic flux generated by the coil 2a is generated by the magnetic shunt layer 3C. Indicates a state of being non-transmissive or non-transmissive to the heat insulating layer 3B. That is, the magnetic shunt layer 3C does not transmit magnetic flux below the Curie point, and the induced magnetic flux does not reach the cored bar 3A.

  On the other hand, FIG. 4B is also a cross-sectional view of the fixing roller 3, and shows a state in which the induced magnetic flux passes through the magnetic shunt layer 3C and the heat insulating layer 3B and reaches the cored bar 3A. The dotted line arrow in the figure is the induced magnetic flux from the core metal 3A made of aluminum or its alloy (see FIG. 4C). That is, since the temperature T of the magnetic shunt alloy layer constituting the magnetic shunt layer 3C is higher than the Curie temperature Tc, the magnetism of the magnetic shunt alloy constituting the magnetic shunt layer 3C is lost and becomes a non-magnetic material, and the presence of the heat insulating layer 3B. Nevertheless, the state in which the induced magnetic flux reaches the cored bar 3A is shown.

  That is, the magnetic shunt layer 3C, which is a magnetic substance (including the function of the heat generating layer described above), increases in temperature almost instantaneously until reaching the Curie point, loses magnetism when reaching the Curie point, and therefore does not increase in temperature. Maintain a constant temperature. Accordingly, if the magnetic material is formed so that the Curie point of the material forming the magnetic shunt layer 3C is 100 to 300 ° C. which is a temperature appearing in this type of fixing device, the heat generating layer 3E of the fixing roller 3 is formed. Further, the core metal 3A is not overheated, and can be maintained at the fixing temperature, and the high releasability and heat resistance on the surface of the fixing roller 3 are not impaired, and complicated control is not required.

  In addition, as a condition that can be deformed when the magnetic shunt layer 3C is a single layer, for example, the material is an alloy containing iron and nickel and the thickness is 150 μm or less. Can be deformed. The magnetic shunt layer 3C may be configured by forming a magnetic material layer by plating on a deformable base layer, for example. The magnetic shunt layer 3C can be reliably deformed, and breakage of the magnetic shunt layer 3C can be reduced.

  The heat insulating layer 3B provided inside the magnetic shunt layer 3C of the fixing roller 3 is preferably made of a material having a lower thermal conductivity than the magnetic shunt layer 3C. Thereby, the thermal efficiency by the heat generating layer 3E improves. The heat insulating layer 3B may be a layer of a material such as foamed silicone rubber (thermal conductivity is 0.1 W / mK) having a lower thermal conductivity than the magnetic shunt layer, but the thermal conductivity of the magnetic shunt layer 3C is, for example, 11 W / mK. If so, for example, other heat insulating layers such as an air layer can be employed as in the illustrated example. The heat insulating layer may or may not include an elastic body. However, if an elastic body is included, the pressing force (nip pressure) by the pressure roller 4 can be increased, so that the fixing property can be excellent.

  In the present embodiment, the thickness of the heat insulating layer 3B is preferably about 10 mm or less, or is formed by deriving an appropriate thickness from a relational expression such as the strength of magnetic flux. This is because it is desirable that the magnetic flux transmitted through the magnetic shunt layer surely passes through the conductor.

  The heat generating rotating body used for fixing may be a roller, a sleeve, or a belt. When the magnetic shunt layer is separate from the heat generating layer, the magnetic shunt layer may or may not be fixed to the heat generating layer. It does not have to be. In the latter case, the belt or sleeve may have a heat generating layer and the roller may have a magnetic shunt layer.

  However, as described above, in such an electromagnetic induction heating type fixing device, a leakage magnetic flux is generated from the heat generating layer 3E as the temperature of the heat generating layer 3E rises, and the temperature immediately before reaching the target temperature for fixing. The rise in temperature slows down and the warm-up time becomes longer. If the Curie point is increased to solve this problem, the target overheating function cannot be obtained.

  Therefore, in this embodiment, as shown in FIG. 5, the Curie point of the magnetic shunt layer 3C is increased, the support layer 3H is provided on the inner side, and the nip is formed on the inner side to face the pressure roller 4. Is provided with a demagnetizing material 3K having a semicircular or semi-elliptical cross section instead of the conventional cored bar 3A, and the magnetic flux generating part 2 is formed in a circular space formed by the support layer 3H. It is supported by a driving device (not shown) so as to be able to contact and separate. As the demagnetizing material 3K, a conductor such as aluminum or an alloy thereof can be used, but the cross-sectional shape is not limited to the shape shown in the figure. Further, as such a demagnetizing material 3K driving device, various mechanisms used for moving elements inside the cylinder in this type of structure can be employed. In FIG. 5, the thick solid arrow indicates the induced magnetic flux from the coil 2a, the fine solid arrow indicates the eddy current, and the dotted arrow indicates the induced magnetic flux from the core 3A made of aluminum or its alloy. .

  FIG. 5A is a cross-sectional view of the fixing roller 3 showing an operation state for enhancing the function of the demagnetizing material 3K. The demagnetizing material 3K is positioned close to the coil 2a (this position is hereinafter referred to as position a). If the temperature T of the magnetic shunt alloy layer constituting the magnetic shunt layer 3C is set to be equal to or higher than the Curie temperature Tc, the magnetic shunt alloy constituting the magnetic shunt layer 3C loses its magnetism and becomes a non-magnetic material and exhibits a high demagnetizing function. .

  On the other hand, FIG. 5B is a cross-sectional view of the fixing roller 3 showing an operation state in which the function of the demagnetizing material 3K is not enhanced. Since the demagnetizing material 3K is located away from the coil 2a (this position is hereinafter referred to as position b), the induced magnetic flux from the coil 2a is transmitted through the magnetic shunt layer 3C, but the magnetic shunt alloy constituting the magnetic shunt layer 3C. Since the temperature T of the layer is higher than the Curie temperature Tc and no induced magnetic flux is generated from the demagnetizing material 3K, the magnetism of the magnetic shunt alloy is not lost and remains a magnetic body.

  That is, since the temperature T of the magnetic shunt alloy layer constituting the magnetic shunt layer 3C is higher than the Curie temperature Tc, a leakage magnetic flux is hardly generated, but an overtemperature function is hardly obtained, but the position of the demagnetizing material 3K is moved. By doing so, desired heat generation suppression control can be performed. FIG. 6 is a graph showing the gap between the heat generating layer and the demagnetizing material 3K made of aluminum and the ratio of magnetic coupling, and FIG. 7 is also the rate of decrease in heat generation (indicated by ▲) and the rate of heat generation suppression (indicated by ● in the figure). It is a figure which shows the ratio of these as a graph. FIG. 8 is a diagram showing the temperature dependence of the heat generation efficiency, when the demagnetizing material as shown in FIG. 5 is functioned (indicated by Δ in the figure) and when it is not functioned (indicated by ○ in the figure). It is shown together. That is, the control of the heat generation of the magnetic shunt layer 3C may be performed based on these data with the position of the demagnetizing material 3K in contact with or away from the coil 2a.

  FIG. 9 is a flowchart showing the operation of the apparatus of this embodiment. First, when the power of the image forming apparatus is turned on (step 1), the home position position of the demagnetizing material 3K (shown as AL (conductor) in the flowchart) (set in advance according to the control content) is confirmed. (Step 2), it is confirmed whether or not the image forming apparatus is in the warm-up state (Step 3). If the image forming apparatus is not in the warm-up state, the AL (conductor) is moved to the position a. Confirm.

  When the image forming apparatus leaves the warm-up state (YES in step 3), the AL (conductor) is moved to the position b, and a signal for instructing a printing operation (or image forming operation) is controlled by the image forming apparatus. It is confirmed whether or not the signal is input to the unit (step 6). If the signal is not input, the operation is terminated. If the signal is input, AL (conductor) is moved to the position a (step 7). Then, a printing operation is performed (step 8). When the printing operation is completed (step 9), the process returns to step 6 to wait for the next signal input.

  FIG. 10 is a cross-sectional view corresponding to FIG. 5 showing Embodiment 2 of the present invention. This embodiment has a structure closer to the general structure of an electromagnetic induction heating type fixing device, has a heat insulating layer 3B made of an elastic body inside the magnetic shunt layer 3C, and further has a non-conductive property inside. A support layer 3H made of a material is disposed. The support layer 3H can be formed of a heat resistant resin, ceramic, or the like. Thus, the heat insulation layer 3B can be arrange | positioned by arrange | positioning the support layer 3H. Although the support layer 3H is not described in the above example, a similar support layer 3H may be disposed inside the heat generating layer 3E of the fixing roller 3.

  Further, a cylindrical demagnetizing material 3K is disposed inside the support layer 3H. The demagnetizing material 3K is a conductive member made of hollow cylindrical aluminum or an alloy thereof, and the demagnetizing material 3K is configured such that its shaft 3L can be rotationally driven by a drive unit (not shown). In this example, the drive unit can rotate independently of the heat generating rotating body. Further, as shown in FIG. 10, the center O of the demagnetizing material 3K is disposed at a position separated from the shaft 3L.

With the configuration as described above, the distance to the magnetic shunt layer can be changed according to the set position in the rotation direction by rotating the demagnetizing material 3K by the drive unit separately from the rotation driving of the fixing roller 3. That is, when the drive unit is operated to bring the center O of the demagnetizing material 3K closer to the magnetic flux generation unit 2 side than the shaft 3L as shown in FIG. It can be. Further, as shown in FIG. 10B, when the center O of the demagnetizing material 3K is brought closer to the opposite side of the magnetic flux generating unit 2 than the shaft 3L, an operation state in which the function of the demagnetizing material 3K is not enhanced is obtained. it can.
The function of the demagnetizing material 3K itself and the demagnetizing effect depending on the position are the same as those described above with reference to FIG. In this example, it is easy to form a nip with the pressure roller 4 due to the presence of the heat insulating layer 3B which is an elastic body.

  FIG. 11 is a cross-sectional view corresponding to FIG. 5 showing Embodiment 3 of the present invention. In this example, as in Example 2, it has a structure closer to the general structure of the electromagnetic induction heating type fixing device, and has a heat insulating layer 3B made of an elastic body inside the magnetic shunt layer 3C. Further, a support layer 3H made of a non-conductive material is disposed inside. The support layer 3H can be formed of a heat resistant resin, ceramic, or the like. Thus, the heat insulation layer 3B can be arrange | positioned by arrange | positioning the support layer 3H.

  A cylindrical demagnetizing material 30 is disposed inside the support layer 3H. The demagnetizing material 30 is a conductive member made of aluminum or an alloy thereof, and the demagnetizing material 30 is configured such that the shaft 3L can be rotationally driven by a drive unit (not shown). In this example, the driving unit can rotate independently of the fixing roller 3.

  As shown in FIG. 11, the demagnetizing material 30 has the same rotation center as the rotation center of the heat generating rotating body, and has a contour that changes stepwise from the rotation center along the rotation direction. That is, the demagnetizing material 30 is provided with surface portions 30a, 30b, and 30c that are divided into three equal parts and have three radii from the center, r1, r2, and r3 (r1> r2> r3). .

  With the configuration described above, the distance to the magnetic shunt layer can be changed depending on the set position in the rotational direction by rotating the demagnetizing material 30 by the driving unit separately from the rotational driving of the fixing roller 3. That is, when the driving unit is operated to place the surface portion 30a of the demagnetizing material 30 on the magnetic flux generating unit 2 side as shown in FIG. 11A, an operation state that enhances the function of the demagnetizing material 3K is obtained. be able to. Further, as shown in FIG. 11B, when the surface portion 30c of the demagnetizing material 30 is arranged in the magnetic flux generating portion 2, an operation state in which the function of the demagnetizing material 3K is not enhanced can be achieved. Similarly, by moving the surface portion 30b to the magnetic flux generating portion 2 side, an intermediate state between the two can be realized. The function of the demagnetizing material 3K itself and the demagnetizing effect depending on the position are the same as those described above with reference to FIG.

1 is a diagram illustrating an embodiment of an image forming apparatus to which a fixing device according to an embodiment is applied. FIG. 2 is a cross-sectional view illustrating a conceptual configuration of a roller-type fixing device that can be used in the image forming apparatus illustrated in FIG. 1. FIG. 3 is a cross-sectional view showing a part of the fixing roller in an enlarged manner. (A) is a cross-sectional view of the fixing roller showing an operation state for enhancing the function of the demagnetizing material, (B) is a cross-sectional view of the fixing roller showing an operation state for not enhancing the function of the demagnetizing material, and (C) is (A), ( It is a figure which shows the meaning of the arrow in B). It is sectional drawing of Example 1 of this invention which has arrange | positioned the demagnetizing material inside the fixing rotary body. It is a figure which shows the ratio of the gap and magnetic coupling of the demagnetizing material which consists of a heat generating layer and aluminum as a graph. It is a figure which similarly shows the ratio of the heat_generation | fever fall rate and the heat_generation | fever suppression rate as a graph. It is a figure which shows the temperature dependence of heat_generation | fever efficiency. It is a flowchart which shows operation | movement of the apparatus of Example 1 of this invention. FIG. 6 is a cross-sectional view corresponding to FIG. 5 illustrating a second embodiment of the present invention, in which (A) is a cross-sectional view of the fixing roller showing an operation state for enhancing the function of the demagnetizing material, and (B) is an operation state for not enhancing the function of the demagnetization material. FIG. FIG. 6 is a cross-sectional view corresponding to FIG. 5 illustrating a third embodiment of the present invention, in which (A) is a cross-sectional view of the fixing roller showing an operation state for enhancing the function of the demagnetizing material, and (B) is an operation state for not enhancing the function of the demagnetization material. FIG.

Explanation of symbols

2: Magnetic flux generation unit 3: Fixing roller (heat generating rotator)
3A: Degaussing layer (core metal)
3B: Heat insulation layer 3C: Magnetic shunt layer 3D1, 3D2: Antioxidation layer 3E: Heat generation layer 3F: Elastic layer 3G: Release layer 3H: Support layer 3J: Pressurizing member 3K: Demagnetizing material 4: Pressure roller (pressurization) Rotating body)
20: Fixing device 30: Demagnetizing material 30a, 30b, 30c: Surface portion 39: Automatic double-sided device 41: Electrophotographic photosensitive member (photosensitive member)
42: Charging device 43: Mirror 44: Developing unit 44a: Developing roller 46: Cleaning unit 46a: Blade 47: Transfer unit 48: Transfer unit 49: Registration roller 110: Feed roller group 150: Exposure unit P: Recording material

Claims (6)

A heat generating rotating body having a heat generating layer that generates heat by magnetic flux;
A magnetic flux generator disposed outside the heat generating rotor and generating magnetic flux;
A magnetic shunt layer formed integrally with or separately from the heat generating layer,
An electric conductor disposed inside the magnetic shunt layer, having a volume resistance lower than that of the magnetic shunt layer, and through which the magnetic flux transmitted through the magnetic shunt layer passes,
In a fixing device for fixing an image on a recording medium by heat generation of the heat generating rotating body,
With placing a support layer constituted by a non-conductive material inside said heating layer,
The fixing device according to claim 1, wherein a contour of the conductor is circular, and a center of the circle is separated from a rotation center of the conductor . 2. The fixing device according to claim 1 , wherein a heat insulating layer is disposed between the heat generating layer and the support layer. The fixing device according to claim 2, wherein the cross-sectional thermal layer is a fixing device which is characterized that you have been formed in the elastic body. 4. The fixing device according to claim 1, further comprising: a driving unit that rotates the conductor independently of the heat-generating rotating body . 5. The fixing device according to any one of claims 1 to 4, wherein the conductive body fixing device being characterized in that the changeable distance between the magnetic shunt layer by setting the position in the direction of rotation. An image forming apparatus comprising the fixing device according to any one of claims 1 to 5