JP2004170625A - Fixing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure capable of obtaining high effect for preventing a leakage magnetic flux to prevent the peripheral metal parts of a fixing device from being heated unnecessarily, in the fixing device adopting an induction heating system. <P>SOLUTION: The surface of a fixing roller 11 as a fixing member is constituted of a metal layer (non-magnetic) 13a, the surface of a pressure belt 21 as a pressure member is constituted of a metal layer (magnetic) 24a, and also, an exciting coil 31 is arranged near a position where the fixing roller 11 comes in contact with the pressure belt 21 inside the fixing roller 11. Besides, a magnetic shielding member 50 is arranged so as to cover the periphery of the fixing roller 11 other than a part where the fixing roller 11 faces the pressure belt 21. And, the eddy current load of the non-magnetic metal constituting the magnetic shielding member 50 is controlled to be ≤ 3.0×10<SP>-4</SP>Ω, especially, ≤ 1.0×10<SP>-4</SP>Ω. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fixing device that inserts a sheet carrying an unfixed toner image into a nip of a heated roller pair, heats and melts the unfixed toner, and fixes the unfixed toner on the sheet. In particular, it relates to a fixing device that heats by a dielectric heating method.
[0002]
[Prior art]
In an electrophotographic image forming apparatus, a heat source is incorporated in at least one of a pair of rollers forming a nip, and a sheet carrying an unfixed toner image is inserted into a nip of the pair of rollers heated by the heat source. A heat roller fixing method for fixing toner on paper by using the method is widely used.
[0003]
In such a heat roller fixing method, the efficiency of heat transfer from a heat source such as a halogen lamp built in the fixing roller to the roller surface is low, and heat loss is large. Further, it takes a long time for heat to be transmitted to the roller surface. As a result, there has been a problem that power consumption is high due to poor heating efficiency, and a certain amount of warm-up time is required until the roller surface reaches a temperature at which fixing can be performed.
[0004]
To improve this, a non-fixed toner is obtained by a dielectric heating method using a fixing roller composed of a non-magnetic metal, which can provide a higher heating efficiency than a magnetic metal by reducing the thickness, and an exciting coil. A fixing device that fuses and fixes an image has been proposed (see Patent Document 1).
[0005]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2000-268952
[Problems to be solved by the invention]
However, when a non-magnetic metal is used, the magnetic field generated by the exciting coil passes through the fixing roller, thereby heating unnecessary metal parts around the fixing roller, wasting heating energy and increasing the temperature inside the apparatus. Let me do it. The fixing device described in Patent Literature 1 attempts to prevent the occurrence of leakage magnetic flux by arranging the excitation coil so as to sandwich the roller from the outside and the inside of the fixing roller, but the effect is not sufficient. .
[0007]
The present invention has been made in view of the above points, and proposes a structure in which a high effect is obtained with respect to prevention of leakage magnetic flux in a fixing device that heats by a dielectric heating method, and eliminates unnecessary heating of metal parts around the device. An object of the present invention is to provide a fixing device that does not perform the fixing. Further, it is another object of the present invention to provide a fixing device that suppresses heat radiation from the heat generating portion.
[0008]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides a fixing device including a fixing member that fixes unfixed toner on a sheet, and a pressure member that forms a nip that abuts the fixing member to insert the sheet. In the above, the material of the fixing member is made of a non-magnetic metal, the material of the pressing member is made of a magnetic metal, and an exciting coil is provided in the fixing member in the vicinity of a position where the fixing member and the pressing member come into contact with each other. The magnetic shielding member made of non-magnetic metal was arranged so as to cover the periphery of the fixing member except for the portion facing the pressing member.
[0009]
According to this configuration, the magnetic shielding member can prevent the magnetic flux from leaking to a place other than the fixing device. Further, since the magnetic shielding member covers the fixing member, radiation of heat from the heat generating portion can be suppressed. As a result, unnecessary heating of the metal portion around the fixing device is not performed, and heat energy is not wasted due to heat radiation. As a result, the effect of keeping the fixing member warm is obtained.
[0010]
Further, a high-permeability member is disposed in the fixing member.
[0011]
According to this configuration, most of the magnetic flux generated from the exciting coil passes through the highly permeable member, so that the magnetic field can be strengthened and the location where the magnetic flux passes can be easily grasped. As a result, it is possible to control the heat generation points in the fixing member and the pressing member. In addition, since the inductance can be improved by the high magnetic permeability member, the size of the excitation coil can be reduced.
[0012]
The eddy current load of the non-magnetic metal layer of the fixing member is in a range from 3.0 × 10 ⁻⁴ Ω to 2.0 × 10 ⁻² Ω.
[0013]
Here, the eddy current load is a value obtained by dividing an electric resistivity specific to a material by a depth at which an eddy current is generated by electromagnetic induction, and is represented by R = ρ / z (where R is an eddy current load. , Ρ is the electrical resistivity, and z is the depth at which the eddy current occurs). Usually, the depth z at which the eddy current occurs is the same as the magnetic field penetration depth δ, and therefore z = δ. However, when the thickness d of the metal layer used is smaller than the magnetic field penetration depth δ, z = d. Therefore, the eddy current load R is R = ρ / d, and is determined by the electric resistivity ρ and the thickness d of the metal layer. Conversely, when the eddy current load R is determined, the thickness d of the metal layer can be derived from the eddy current load R and the electric resistivity ρ.
[0014]
Generally, when heating is performed by the dielectric heating method, it is desirable to use a magnetic metal as the heating element. However, according to this configuration, it is possible to obtain higher heating efficiency than using a magnetic metal. In addition, high heating efficiency can be obtained irrespective of the type of non-magnetic metal forming the surface of the fixing member. As a result, it is possible to determine the appropriate layer thickness for those metals and it is easier to actually fabricate. Further, the heating performance is better than those manufactured based on other numerical values.
[0015]
According to another aspect of the present invention, there is provided a fixing device including a fixing member that fixes unfixed toner on a sheet, and a pressing member that forms a nip that abuts the fixing member to insert the sheet. The material is made of a magnetic metal, the material of the pressing member is made of a non-magnetic metal, and an exciting coil is arranged in the pressing member in the vicinity of a position where the pressing member and the fixing member come into contact with each other. A magnetic shielding member made of a non-magnetic metal was arranged so as to cover the periphery of the member except for the portion facing the fixing member.
[0016]
According to this configuration, the magnetic shielding member can prevent the magnetic flux from leaking to a place other than the fixing device. Further, since the magnetic shielding member covers the pressure member, the radiation of heat from the heat generating portion can be suppressed. As a result, unnecessary heating of the metal portion around the fixing device is not performed, and heat energy is not wasted due to heat radiation. Then, the heat retaining function of the pressing member is obtained.
[0017]
In addition, a high-permeability member is arranged in the pressure member.
[0018]
According to this configuration, most of the magnetic flux generated from the exciting coil passes through the highly permeable member, so that the magnetic field can be strengthened and the location where the magnetic flux passes can be easily grasped. As a result, it is possible to control the heat generation points in the fixing member and the pressing member. In addition, since the inductance can be improved by the high magnetic permeability member, the size of the excitation coil can be reduced.
[0019]
The eddy current load of the non-magnetic metal layer of the pressing member is in a range from 3.0 × 10 ⁻⁴ Ω to 2.0 × 10 ⁻² Ω.
[0020]
Generally, when heating is performed by the dielectric heating method, it is desirable to use a magnetic metal as the heating element. However, according to this configuration, it is possible to obtain higher heating efficiency than using a magnetic metal. Also, high heating efficiency can be obtained regardless of what kind of metal the non-magnetic metal constituting the surface of the pressing member is. As a result, it is possible to determine the appropriate layer thickness for those metals and it is easier to actually fabricate. Further, the heating performance is better than those manufactured based on other numerical values.
[0021]
In addition, the eddy current load of the magnetic shielding member is 3.0 × 10 ⁻⁴ Ω or less.
[0022]
In general, when heating by a dielectric heating method, it is difficult to heat a non-magnetic metal, but heating is facilitated by reducing the thickness and changing the eddy current load. However, according to the above configuration, the magnetic shielding member is not heated by the dielectric heating method. As a result, it is possible to shield magnetic flux leakage without unnecessary heating of the metal part around the fixing device.
[0023]
Further, the eddy current load of the magnetic shielding member is set to 1.0 × 10 ⁻⁴ Ω or less.
[0024]
As described above, by further reducing the eddy current load of the nonmagnetic metal layer of the magnetic shielding member, the safety against preventing the magnetic shielding member from being heated by the dielectric heating method is increased. As a result, it is possible to provide a fixing device with higher heating efficiency.
[0025]
Further, the high magnetic permeability member is made of ferrite.
[0026]
According to this configuration, it is possible to use a ferrite widely used as a high magnetic permeability member, and to increase the heating efficiency with a simple configuration.
[0027]
Further, both the fixing member and the pressing member are constituted by rollers.
[0028]
According to this configuration, the main components constituting the fixing device are only the fixing roller and the pressure roller, so that the structure can be simplified and the device can be made more compact. Further, cost can be reduced by reducing the number of parts.
[0029]
Further, one of the fixing member and the pressing member is constituted by a roller, and the other is constituted by a belt.
[0030]
According to this configuration, the heat capacity can be reduced by using a belt for one of the fixing member and the pressing member as compared with the case where both of the fixing member and the pressing member are rollers. Also, an appropriate nip time can be set. As a result, the time required for the fixing member surface to reach a fixing temperature can be further reduced. In addition, stable fixing properties can be obtained.
[0031]
Further, both the fixing member and the pressing member are constituted by belts.
[0032]
According to this configuration, the heat capacity of the fixing member and the pressure member can be further reduced. As a result, it is possible to further shorten the time required for the surface of the fixing member to reach a temperature at which fixing can be performed.
[0033]
Further, the magnetic shielding member that covers the fixing member and / or the pressing member constituted by the roller has a gutter shape coaxial with the roller.
[0034]
According to this configuration, the heat radiated from the heat generating portion can be reflected with higher efficiency. As a result, waste of heating energy is small, and high heat retention can be obtained.
[0035]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0036]
FIG. 1 is a schematic sectional view showing a fixing device according to a first embodiment of the present invention. FIG. 2 is a schematic partial perspective view of the electromagnetic induction unit of the fixing device shown in FIG. The fixing device 1 includes a fixing unit 10 and a pressure unit 20, and an electromagnetic induction unit 30 is disposed in a fixing roller 11 which is a fixing member of the fixing unit 10. A magnetic shielding member 50 is provided outside the fixing unit 10, and a cover 60 is further provided outside. A paper entry guide 40 is provided at a position where the paper enters.
[0037]
The fixing unit 10 includes a fixing roller 11 as a fixing member. The fixing roller 11 has a diameter of 40 mm, and is provided with a metal layer (non-magnetic) 13 a on the surface of a core material 12 such as a heat-resistant resin. When the metal layer (nonmagnetic) 13a is, for example, SUS304 (a stainless steel type according to Japanese Industrial Standards), its thickness is 250 μm. A release layer 14 having a thickness of 20 μm is provided outside the metal layer (nonmagnetic) 13a to enhance the releasability of the toner. The release layer 14 is made of a fluorine-based resin such as PFA (tetrafluoroethylene-per-fluoroalkylvinyl ether copolymer), and is provided by spraying a coating or covering a tube. As the elastic layer, a silicon rubber layer may be provided between the core 12 and the metal layer (nonmagnetic) 13a.
[0038]
The pressing unit 20 includes a pressing belt 21 as a pressing member, a main roller 22, and a sub-roller 23. The pressure belt 21 in contact with the fixing roller 11 is provided with nickel having a thickness of 50 μm as a metal layer (magnetic) 24 a by electroforming, and a silicon rubber layer having a thickness of 100 μm is provided as an elastic layer 25 on the outside thereof. ing. Further outside, a 50 μm-thick PFA tube is covered as a release layer 26. A predetermined tension is applied to the pressure belt 21 by the main roller 22 and the sub roller 23, and the pressure belt 21 contacts the fixing roller 11 to form a nip through which a sheet is inserted.
[0039]
Here, the configuration of the fixing roller 11 and the pressing unit 20 may be a configuration in which the fixing roller 11 is replaced with a belt and the pressing unit 20 is only a roller. Further, both may be rollers or both may be belts. In any case, an excitation coil 31 described later is arranged in the fixing member in the vicinity of a position where the fixing member and the pressing member come into contact with each other. When the fixing roller 11 is replaced by a belt, a non-magnetic metal layer is provided on the polyimide film by plating or rolling, and the outside thereof is coated with a fluorine-based resin such as PFA.
[0040]
The electromagnetic dielectric unit 30 includes an exciting coil 31, a ferrite 32, and a support member 33. The exciting coil 31 is formed by winding a litz wire, which is made up of 300 enamel wires having a diameter of 0.1 mm, in a direction along the axis of the fixing roller 11. A ferrite 32 for strengthening the magnetic field is provided inside the exciting coil 31 wound in this manner. The support member 33 is made of a heat-resistant resin, and includes a ferrite storage portion 33a and a curved portion 33b formed based on the curvature of the fixing roller 11. The excitation coil 31 is wound so as to surround the ferrite storage portion 33a and to extend along the curved portion 33b. The excitation coil 31 is connected to a high-frequency power supply 34 having a rated power of 1500 W and a frequency of 20 to 50 kHz. Note that the ferrite 32 can be replaced with a member other than ferrite as long as the member has a high magnetic permeability.
[0041]
The electromagnetic dielectric part 30 is disposed in the fixing roller 11 with the exciting coil 31 approaching the contact point so that the magnetic flux passes through the contact point between the fixing roller 11 and the pressure belt 21.
[0042]
In addition, a thermistor 15 is provided between the inner wall of the fixing roller 11 and the electromagnetic dielectric unit 30 in the vicinity of a portion of the fixing roller 11 where the fixing roller 11 and the pressure belt 21 abut. The temperature of the heating unit is detected by the thermistor 15 and the output of the high frequency power supply 34 is controlled to perform temperature control.
[0043]
The magnetic shielding member 50 is made of aluminum, which is a non-magnetic metal having a thickness of 1 mm. The magnetic shielding member 50 has a gutter shape coaxial with the fixing roller 11, and is arranged so as to cover the periphery of the fixing roller 11 except for a portion facing the pressure belt 21. The axial length of the magnetic shielding member 50 is the same as that of the fixing roller 11. Note that it is not necessary to be strictly coaxial with the fixing roller 11, and even if there is a slight displacement, the effect can be exhibited.
[0044]
FIG. 3 is a schematic sectional view showing a heating state by the fixing device shown in FIG. The fixing device 1 performs a heating operation as follows.
[0045]
When a high-frequency current flows through the exciting coil 31, a magnetic field is generated. Most of the generated magnetic fluxes Ma and Mb pass through the ferrite 32, which is a highly permeable member, so that the magnetic field can be strengthened. When the generated magnetic fluxes Ma and Mb pass through the metal layer (nonmagnetic) 13a of the fixing roller 11, an eddy current flows through the metal in the passing areas A and B, and heat is generated by the electric resistance of the metal. In particular, the passing area A generates a large amount of heat because the presence of the metal layer (magnetic) 24a causes the magnetic field to concentrate more than the passing area B. Further, since the magnetic flux Ma also passes through the pressure belt 21, the metal layer (magnetic) 24a of the pressure belt 21 also generates heat at the same time.
[0046]
Here, when the magnetic shielding member 50 is not present and the cover 60 is made of a magnetic metal such as iron, the magnetic flux Mb passes through the fixing roller 11 made of a non-magnetic metal. There is a risk of getting it. Therefore, as shown in FIG. 3, by disposing the magnetic shielding member 50 so as to cover the periphery of the fixing roller 11, it is possible to prevent the magnetic flux Mb from leaking to the periphery of the outside of the fixing roller 11. It is possible to prevent heating.
[0047]
Further, by covering the fixing roller 11 with the magnetic shielding member 50, heat radiation from the fixing roller 11 is prevented, so that heating energy is not wasted. Further, by forming the magnetic shielding member 50 in a gutter shape, the heat radiated from the heat generating portion can be reflected with higher efficiency, and the heat retaining property of the fixing roller 11 can be improved. Thereby, high heating efficiency and stable fixing properties can be obtained.
[0048]
FIG. 4 is a schematic sectional view showing a fixing device according to a second embodiment of the present invention. FIG. 5 is a schematic partial perspective view of the electromagnetic induction unit of the fixing device shown in FIG. The basic configuration of the fixing device 1 is the same as that of the first embodiment shown in FIG. The electromagnetic induction section 30 is disposed inside a pressure belt 21 which is a pressure member of the pressure section 20. Further, a magnetic shielding member 50 is provided outside the pressurizing unit 20, and a cover 60 is further provided outside the pressurizing unit 20.
[0049]
The fixing unit 10 includes a fixing roller 11 as a fixing member. The fixing roller 11 has a diameter of 40 mm, and a metal layer (magnetic) 13b is provided on the surface of a core material 12 such as a heat-resistant resin. The metal layer (magnetic) 13b is formed by plating nickel or the like. Further, the core 12 may be formed of a metal tube such as iron. A release layer 14 made of a fluorine-based resin such as PFA having a thickness of 20 μm is provided on the outside of the metal layer (magnetic) 13b to enhance the releasability of the toner. Further, as the elastic layer, a silicon rubber layer may be provided between the core material 12 and the metal layer (magnetic) 13b.
[0050]
The pressing unit 20 includes a pressing belt 21 as a pressing member, a main roller 22, and a sub-roller 23. The pressure belt 21 in contact with the fixing roller 11 has a 50 μm-thick SUS304 formed as a metal layer (non-magnetic) 24 b, and a 100 μm-thick silicon rubber layer provided as an elastic layer 25 on the outside thereof. Further outside, a 50 μm-thick PFA tube is covered as a release layer 26. The metal layer (nonmagnetic) 24b may be provided on the outside of the polyimide film by plating or rolling copper or aluminum.
[0051]
As in the first embodiment, the configuration of the fixing roller 11 and the pressing unit 20 may be either a roller, one of which is a roller and the other is a belt, or both are a belt.
[0052]
The electromagnetic dielectric unit 30 includes an exciting coil 31, a ferrite 32, and a support member 33. The excitation coil 31 is wound so as to surround a ferrite storage portion 33 a provided on the support member 33, and is connected to a high-frequency power supply 34. Note that the ferrite 32 can be replaced with a member other than ferrite as long as the member has a high magnetic permeability. The electromagnetic dielectric unit 30 is disposed inside the pressure belt 21 with the excitation coil 31 close to the contact point so that the magnetic flux passes through the contact point between the fixing roller 11 and the pressure belt 21.
[0053]
In addition, a thermistor 15 is provided in the fixing roller 11 near a position where the fixing roller 11 and the pressure belt 21 are in contact with each other. The temperature of the heating unit is detected by the thermistor 15 and the output of the high frequency power supply 34 is controlled to perform temperature control.
[0054]
The magnetic shielding member 50 is made of aluminum, which is a non-magnetic metal having a thickness of 1 mm, and is arranged in a gutter shape so as to cover the periphery of the pressure belt 21 except for a portion facing the fixing roller 11. ing. The length of the magnetic shielding member 50 in the axial direction is the same as that of the pressure belt 21.
[0055]
FIG. 6 is a schematic cross-sectional view showing a heating state by the fixing device shown in FIG. The fixing device 1 performs a heating operation as follows.
[0056]
When a high-frequency current flows through the exciting coil 31, a magnetic field is generated. Most of the generated magnetic fluxes Mc and Md pass through the ferrite 32, which is a highly permeable member, so that the magnetic field can be strengthened. When the generated magnetic fluxes Mc and Md pass through the metal layer (non-magnetic) 24b of the pressure belt 21 and the metal layer (magnetic) 13b of the fixing roller 11, an eddy current flows through the metal in the passing areas C and D, Generates heat due to the electrical resistance of In particular, the passing area C generates a large amount of heat because the presence of the metal layer (magnetic) 13b concentrates the magnetic field more than the passing area D. Further, since this magnetic flux Mc passes through the pressure belt 21 and the fixing roller 11 at the same time, both members generate heat.
[0057]
Here, when the magnetic shielding member 50 is not present and the cover 60 is made of a magnetic metal such as iron, the magnetic flux Md passes through the pressure belt 21 made of a non-magnetic metal, so that the cover 60 is heated. There is a risk that it will. Therefore, as shown in FIG. 6, by disposing the magnetic shielding member 50 so as to cover the periphery of the pressure belt 21, the magnetic flux Md is prevented from leaking to the outer periphery of the pressure belt 21. It is possible to prevent the necessary heating.
[0058]
Further, by covering the pressure belt 21 with the magnetic shielding member 50, heat radiation from the pressure belt 21 is prevented, so that waste of heating energy is reduced. Further, by forming the magnetic shielding member 50 in a gutter shape, the heat radiated from the heat generating portion can be reflected with higher efficiency, and the heat retention of the pressure belt 21 can be improved. Thereby, high heating efficiency and stable fixing properties can be obtained.
[0059]
It should be noted that the numerical values such as dimensions appearing so far are only examples of one preferred example, and do not limit the scope of the invention.
[0060]
FIG. 7 is a graph showing the relationship between the thickness of the metal forming the fixing member and the pressing member and the eddy current load. The horizontal axis of the graph indicates the thickness of the metal, and the vertical axis indicates the eddy current load of the metal. Examples of the type of metal include copper, aluminum, and SUS304, which are nonmagnetic metals, and iron and nickel, which are magnetic metals.
[0061]
In the figure, a region E indicates a range of a metal eddy current load that can be easily heated by the dielectric heating method. That is, if the eddy current load of the metal constituting the fixing member and the pressing member is in the range of 3.0 × 10 ⁻⁴ Ω to 2.0 × 10 ⁻² Ω, heating can be easily performed by the dielectric heating method. is there. For example, in the case of copper, if the eddy current load is 3.0 × 10 ⁻⁴ Ω or more, that is, if the thickness is less than 55 μm, heating becomes possible, so that the fixing roller 11 in the first embodiment or the It can be used as the non-magnetic metal layer of the pressure belt 21 in the second embodiment.
[0062]
Further, if the eddy current load of copper is 3.0 × 10 ⁻⁴ Ω or less, that is, if the thickness is more than 55 μm, it becomes difficult to heat, so that it is used as the magnetic shielding member 50 in the first and second embodiments. Can be.
[0063]
Further, by reducing the eddy current load of copper to 1.0 × 10 ⁻⁴ Ω or less, that is, by increasing the thickness to 165 μm or more, it is possible to prevent the magnetic shielding member 50 from being heated by the dielectric heating method. Increases safety. As a result, it is possible to provide a fixing device with higher heating efficiency.
[0064]
Although the embodiment of the present invention has been described above, other various modifications can be made without departing from the gist of the present invention.
[0065]
【The invention's effect】
According to the configuration of the present invention, it is possible to prevent the magnetic flux from leaking to a place other than the fixing device by the magnetic shielding member. Further, since the magnetic shielding member covers the member including the excitation coil, it is possible to suppress the radiation of heat from the heat generating portion. As a result, unnecessary heating of the metal portion around the fixing device is not performed, and heat energy is not wasted due to heat radiation. Then, the fixing member or the pressure member can have a heat retaining action.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view showing a fixing device according to a first embodiment of the present invention; FIG. 2 is a schematic partial perspective view of an electromagnetic induction unit shown in FIG. 1; FIG. FIG. 4 is a schematic cross-sectional view showing a state. FIG. 4 is a schematic cross-sectional view showing a fixing device according to a second embodiment of the present invention. FIG. 5 is a schematic partial perspective view of an electromagnetic induction unit shown in FIG. FIG. 7 is a schematic cross-sectional view showing a heating state by the fixing device shown in FIG. 4. FIG. 7 is a graph showing a relationship between metal thickness and eddy current load.
DESCRIPTION OF SYMBOLS 1 Fixing device 10 Fixing part 11 Fixing roller 13a Metal layer (non-magnetic)
13b Metal layer (magnetic)
Reference Signs List 20 pressure unit 21 pressure belt 22 main roller 24a metal layer (magnetic)
24b metal layer (non-magnetic)
Reference Signs List 30 electromagnetic induction unit 31 excitation coil 32 ferrite 50 magnetic shielding member 60 cover

Claims (13)

A fixing device comprising: a fixing member that fixes unfixed toner on a sheet; and a pressure member that forms a nip that abuts the fixing member to insert the sheet.
The material of the fixing member is made of a non-magnetic metal, the material of the pressing member is made of a magnetic metal, and an exciting coil is arranged in the fixing member near a position where the fixing member and the pressing member come into contact with each other. And a magnetic shielding member made of a non-magnetic metal is disposed so as to cover the periphery of the fixing member except for a portion facing the pressure member. The fixing device according to claim 1, wherein a high magnetic permeability member is disposed inside the fixing member. The eddy current load of the nonmagnetic metal layer of the fixing member is in a range of 3.0 × 10 ⁻⁴ Ω to 2.0 × 10 ⁻² Ω. Fixing device. A fixing device comprising: a fixing member that fixes unfixed toner on a sheet; and a pressure member that forms a nip that abuts the fixing member to insert the sheet.
The material of the fixing member is made of a magnetic metal, the material of the pressing member is made of a non-magnetic metal, and an exciting coil is arranged in the pressing member near a position where the pressing member and the fixing member abut. And a magnetic shielding member made of a non-magnetic metal is disposed so as to cover the periphery of the pressing member except for a portion facing the fixing member. The fixing device according to claim 4, wherein a high-permeability member is disposed inside the pressure member. The eddy current load of the nonmagnetic metal layer of the pressing member is in a range of 3.0 × 10 ⁻⁴ Ω to 2.0 × 10 ⁻² Ω. Fixing device. The fixing device according to claim 1, wherein an eddy current load of the magnetic shielding member is 3.0 × 10 ⁻⁴ Ω or less. The fixing device according to claim 1, wherein an eddy current load of the magnetic shielding member is 1.0 × 10 ⁻⁴ Ω or less. 9. The fixing device according to claim 1, wherein the high-permeability member is ferrite. The fixing device according to claim 1, wherein both the fixing member and the pressing member are configured by rollers. The fixing device according to claim 1, wherein one of the fixing member and the pressing member is configured by a roller, and the other is configured by a belt. The fixing device according to claim 1, wherein both the fixing member and the pressing member are configured by a belt. The fixing device according to claim 10, wherein the magnetic shielding member that covers the fixing member and / or the pressing member formed of the roller has a gutter shape that is coaxial with the roller.

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