JP2002043049A - Induction heating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an induction heating device capable of generating uniform and sufficient heating energy, without making the device large-size. SOLUTION: A heating roller 11 is provided with a conductive layer 13 to generate heat in an alternating field. An induction coil 15, comprising folded parts 15a at both end parts of length of the heat roller 11, and straight part 15b in parallel along the length, is disposed to enclose one side of the heating roller 11. Longitudinal length of the heating roller 11 is substantially similar to that of the induction coil 15, and for compensating reduction of interlinkage flux on the end part side of the heating roller 11 by that, conductors at the folded parts 15a of the induction coil 15 at the end parts are layered. In a section W where the heating roller 11 passes the induction coil 15, therefore, interlinkage flux at each longitudinal end part of the heating roller can be made substantially similar to that at other parts, thereby uniform and sufficient heating energy can be generated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction heating system which is preferably used in a fixing device in a dry electrophotographic apparatus, a drying apparatus in a wet electrophotographic apparatus, a drying apparatus in an ink jet printer, an erasing apparatus for rewritable media and the like. Heating device.

[0002]

2. Description of the Related Art In a conventional heating device, for example, in a fixing device, a halogen lamp is provided in a heating roller,
A configuration in which a heating roller is heated by the halogen lamp has been widely used. However, there is a problem that the rise at the start of heating is slow,
In recent years, by forming a heating roller with a conductive layer and applying an alternating magnetic field from the magnetic field generating means to the heating roller, the heating roller itself generates heat using Joule heat generated by eddy current generated in the heating roller. Attention has been paid to such an induction heating type fixing device.

FIG. 22A is a plan view of a typical prior art induction heating type fixing device 170, and FIG.
22A is a side view of FIG. 22A, and FIG.
It is sectional drawing seen from the cutting surface line II of (b). The recording paper on which the toner image is formed is nipped and conveyed by the heating roller 1 and the pressure roller 2 of the fixing device 170,
The toner image is fixed by heating. The heating roller 1 includes:
It has a conductive layer 3 that generates heat in an alternating magnetic field. An induction coil 4 which extends parallel to the longitudinal direction of the heating member so as to surround one of the heating rollers 1 and is folded at both longitudinal ends.
Are arranged. An alternating current is applied to the induction coil 4 from an excitation circuit, and the alternating electric field caused by the alternating current causes the conductive layer 3.
Generates an eddy current, which is heated by electromagnetic induction.

A further induction heating type fixing device is disclosed in Japanese Patent No. 2,616,433. FIG. 23 is a diagram showing the fixing device 200. The fixing device 200
Is based on a roller pair consisting of a heating roller 201 and a pressure roller 202, and the heating roller 201 is
The temperature is raised to a predetermined temperature by receiving an alternating magnetic field generated by an induction heating body 207 composed of a heating coil 209 and an insulating support body 208 arranged on one side outer peripheral portion of the heating roller 201.

On the other hand, the recording paper 2 having an unfixed image sent to the fixing device 200 through a developing step (not shown)
The unfixed image is fixed to the recording paper 216 by heat and pressure by passing through the contact nip formed by the heating roller 201 and the pressure roller 202 heated to a predetermined temperature. .

Here, when the length of the heating coil 209 is formed substantially equal to the length of the heating roller 201 and small-sized paper is processed, the area where the recording paper 216 passes is limited to the recording paper 21.
Although the heat is taken by 6 and the temperature decreases, the temperature rises due to heat storage in the non-passable region. When processing large-sized paper in this state, toner adheres to the heating roller in a high-temperature region (both ends of the paper), causing a so-called high-temperature offset problem that causes image loss.

Therefore, in the fixing device 200, FIG.
, The heating coil (induction coil) 209 is divided along the axial direction of the heating roller 201 into three parts, a central part shown by reference numeral 209a and both end parts shown by reference numerals 209b and 209c. And are configured to be independently energized. With this configuration,
For processing a sheet having a small width, a method of changing a heating area according to the sheet size, such as heating only a central heating coil, is described.

[0008]

However, as a first problem, in the fixing device 170 shown in FIG. 22, the induction coil 4 is turned on the end side of the heating roller 1.
Since the portion 4a is exposed, there is a problem that the flux linkage at the end of the heating roller 1 is smaller than the flux linkage at the other portions. That is, the induction coil 4
The linear portion 4b faces the portion other than the end of the heating roller 1, and a magnetic field indicated by an arrow B1 effectively acts on this portion. The folded portion 4a is exposed, and much of the magnetic field indicated by the arrow B2 passes outside the heating roller 1 and does not function effectively. In order to solve this problem, the length L of the linear portion 4b of the induction coil 4 may be longer than the length of the heating roller 1.
In particular, it is not practical for a small copying machine.

The second problem is that, in Japanese Patent No. 2616433, since the heating coil 209 is divided into a plurality of parts, an excitation circuit is prepared for each coil and each is driven independently or one excitation circuit is provided. It has been proposed to switch circuits for use. When an excitation circuit is prepared for each coil, each circuit is set to, for example, 20 kHz.
At the above-mentioned high frequency, it is required to control a large current of 10 A or more with high accuracy, which causes a problem that the cost is increased. On the other hand, when one excitation circuit is switched and used, problems such as generation of noise due to the high-frequency current and voltage drop occur at the switching terminal.

[0010] As shown in FIG.
The winding pattern 09 is divided into two parts, a part A parallel to the axial direction of the heating roller 201 and a part B parallel to the circumferential direction. Since the generated alternating magnetic field is generated on a plane perpendicular to the direction in which the current flows, the direction of the generated magnetic field differs between A and B. Therefore, it is difficult to make the magnetic field distribution in the longitudinal direction of the heating roller 201 uniform, and it is difficult to maintain uniform temperature characteristics in the axial direction. This tendency is particularly remarkable when the coil is divided in the longitudinal direction. Therefore, by dividing the heating coil in this way, it is possible to cope with paper having different width dimensions, but it is difficult to realize a uniform temperature characteristic with respect to the maximum paper size with such a configuration. Problem.

A first object of the present invention is to provide an induction heating apparatus capable of generating uniform and sufficient heating energy without increasing the size of the apparatus.

A second object of the present invention is to increase the temperature of a heating member only at a required portion even if heat-treated materials of different sizes are continuously heated with a simple structure, so that the temperature is uniform and uniform. An object of the present invention is to provide an induction heating device capable of heating.

[0013]

According to the present invention, there is provided an elongated heating member having a conductive layer that generates heat in an alternating magnetic field, a winding member extending parallel to the longitudinal direction of the heating member, and folded at both ends in the longitudinal direction. An induction coil, which is composed of a conductive wire that is turned and is arranged so as to surround one side of the heating member, wherein the heating member is electromagnetically heated by an alternating magnetic field from the induction coil, and the opposite side to the induction coil. In an induction heating device for transmitting heat of a heating member to a material to be heated provided on the other side of a heating member to be formed, the heating member and the induction coil are formed to have substantially equal longitudinal lengths, and the longitudinal length of the heating member is In order to compensate for the decrease of the flux linkage to the conductive layer at both ends in the direction, the induction coil at the end is laminated and wound in a direction perpendicular to the longitudinal direction of the heating member. It is an induction heating device.

According to the present invention, in order to compensate for a reduction in the interlinkage magnetic flux at both ends of the heating member, the induction coil turned back at the end is laminated in a direction perpendicular to the longitudinal direction of the heating member. By winding, the linear portion of the induction coil can be widely used, even if the length of the heating member and the induction coil are made substantially equal so that the device does not become large, and the heating can be performed. The member generates heat uniformly over its entire length, has a simple configuration, and can eliminate temperature unevenness.

According to the present invention, there is also provided a heating member having a conductive layer which generates heat in an alternating magnetic field, and a conductive wire which extends parallel to the longitudinal direction of the heating member and is wound at both ends in the longitudinal direction. An induction coil disposed so as to surround one side of the heating member, and the electromagnetic induction heating of the heating member by an alternating magnetic field from the induction coil, the heating member being on the side opposite to the induction coil. In an induction heating device that transmits heat of a heating member to a material to be heated provided on the other side,
The heating member and the induction coil are formed to have substantially the same length in the longitudinal direction. In order to compensate for a decrease in magnetic flux linkage to the conductive layer at both ends in the longitudinal direction of the heating member, the heating member and the induction coil are folded back at the end side. An induction heating device characterized in that a loop diameter of an induction coil is enlarged and wound.

According to the present invention, in order to compensate for the decrease in the interlinkage magnetic flux at both ends of the heating member, the loop diameter of the folded induction coil at the end is enlarged, and the center and the end are connected to each other. In the two-dimensional direction, that is, by adjusting the width of the induction coil to be larger at the end than at the center, thereby increasing the passage time of the conductive layer in the interlinkage magnetic flux. Thus, even if the longitudinal lengths of the heating member and the induction coil are substantially equal to each other, the heating member generates heat uniformly over the entire length so that the device has a simple configuration and eliminates temperature unevenness so that the apparatus is not increased in size. Can be.

According to the present invention, there is also provided a heating member having a conductive layer which generates heat in an alternating magnetic field, and a conductive wire which extends parallel to the longitudinal direction of the heating member and is wound at both ends in the longitudinal direction. An induction coil disposed so as to surround one side of the heating member, and the electromagnetic induction heating of the heating member by an alternating magnetic field from the induction coil, the heating member being on the side opposite to the induction coil. In an induction heating device that transmits heat of a heating member to a material to be heated provided on the other side,
The heating member and the induction coil are formed to have substantially the same length in the longitudinal direction. In order to compensate for the decrease in the magnetic flux linkage to the conductive layer at both ends in the longitudinal direction of the heating member, a second portion is provided at the end. Wherein the second conductive layer is formed from a material having a higher relative magnetic permeability or volume resistivity than the conductive layer.

According to the present invention, a second conductive layer is provided at the end of the heating member so as to compensate for the decrease in the interlinkage magnetic flux at both ends of the heating member. It is made of a material having a higher magnetic permeability or volume resistivity than the conductive layer, and efficiently generates heat even with a small interlinkage magnetic flux. by this,
Even if the lengths of the heating member and the induction coil in the longitudinal direction are substantially equal so that the apparatus is not increased in size, the heating member generates heat uniformly over the entire length, and can have a simple configuration to eliminate temperature unevenness.

The present invention also provides a heating member having a conductive layer that generates heat in an alternating magnetic field, and a conductive wire extending parallel to the longitudinal direction of the heating member and folded at both ends in the longitudinal direction and wound. An induction coil disposed so as to surround one side of the heating member, and the electromagnetic induction heating of the heating member by an alternating magnetic field from the induction coil, the heating member being on the side opposite to the induction coil. In an induction heating device that transmits heat of a heating member to a material to be heated provided on the other side,
The heating member and the induction coil are formed to have substantially the same length in the longitudinal direction. In order to compensate for the decrease in the flux linkage to the conductive layer at both ends in the longitudinal direction of the heating member, the induction on the end side is compensated. An induction heating device characterized in that a heat conducting member that is heated by electromagnetic induction is provided at a folded portion of the coil.

According to the present invention, in order to compensate for a reduction in the interlinkage magnetic flux at both ends of the heating member, the heating member is close to the loop portion of the induction coil folded back at the end portion and is orthogonal to the conductor of the induction coil. That is, a heat conductive member provided with a plurality of magnetic members parallel to the generated magnetic flux is provided. Therefore, the magnetic member efficiently captures the magnetic flux, the eddy current generated in the magnetic member increases, and the calorific value increases. In this way, the heat generated in the magnetic member is transmitted to the heat conducting member and is given to the end of the heating member by heat radiation. Thereby, even if the length of the heating member in the longitudinal direction of the induction coil is substantially equal so that the apparatus does not become large, it is possible to generate heat uniformly over the entire heating member, and it is possible to eliminate temperature unevenness with a simple configuration. it can.

According to the present invention, there is further provided a heating member having a conductive layer which generates heat in an alternating magnetic field, and a conductive wire which extends in parallel with the longitudinal direction of the heating member and is wound at both ends in the longitudinal direction. An induction coil disposed so as to surround one side of the heating member, and the electromagnetic induction heating of the heating member by an alternating magnetic field from the induction coil, the heating member being on the side opposite to the induction coil. In an induction heating device that transmits heat of a heating member to a material to be heated provided on the other side,
A magnetic member that is arranged along the induction coil and is divided into a plurality of parts in the longitudinal direction of the induction coil, and a part or all of the magnetic member moves toward and away from the induction coil according to the size of the material to be heated. An induction heating apparatus comprising:

In a heating device using an induction heating method,
When a magnetic member realized by ferrite or the like is provided adjacent to the magnetic field generating means realized by the induction coil,
Of the generated alternating magnetic field, the magnetic flux on the back side can be concentrated. When the magnetic flux on the back side is concentrated, the density of the magnetic flux linked to the heating member located on the opposite side increases due to the influence. As a result, the eddy current generated in the heating member increases, the amount of heat generation increases, and the heating efficiency is improved.

However, when the magnetic member is provided over the entire length of the induction coil in the longitudinal direction, if the material to be heated such as recording paper has the maximum applicable size, the material to be heated is uniformly heated. However, in the case of a small size, heat transfer is not performed in a portion that is not in contact with the material to be heated, such as near both ends in the longitudinal direction of the heating member, and the temperature rises due to heat storage. When processing the next-larger heated material in that state, temperature unevenness occurs between the portion that was in contact with the smaller-sized heated material and the portion that was not in contact, such as a high-temperature offset. This leads to poor fixing.

According to the present invention, the magnetic member is divided into a plurality of pieces in the longitudinal direction so that the temperature unevenness does not occur, and only the magnetic member facing the portion is divided according to the size of the material to be heated. Move closer to the induction coil. In this way, with a simple configuration in which the divided magnetic members are selectively displaced toward and away from the induction coil, even if the heat-treated materials of different sizes are continuously heated, the heating members are raised only at necessary places. It can be heated and evenly heated without unevenness.

Further, by using a relatively long magnetic member in combination with a plurality of divided relatively short magnetic members, cracking of the temperature of the heating member is less likely to occur, and the yield can be improved. .

Furthermore, since the magnetic member allows the magnetic flux to be efficiently concentrated on the heating member, the distance between the heating member and the induction coil can be increased. That is, it is possible to make the induction coil less affected by the temperature of the heating member. As a result, it is possible to prevent the rise in coil resistance by lowering the ambient temperature and improve the heating efficiency.

Further, since the magnetic field generating means is arranged so as to surround the heating member, when the heating member is a heating roller, the induction coil which is the magnetic field generating means has a curvature and is arranged outside the heating member. Therefore, the effect of concentrating the magnetic flux on the heating member is large, and the magnetic flux can be effectively concentrated with a small amount of the magnetic member.

Further, according to the present invention, the division surface of the magnetic member may be:
The heating member intersects with a cross section perpendicular to the axis.

If the divided surface of the divided magnetic member is formed in parallel with the cross section perpendicular to the axis of the heating member, the magnetic flux in the gap where the magnetic member is interrupted will not be concentrated, and the temperature of the heating member corresponding to that portion will not be concentrated. And temperature unevenness occurs. According to the present invention, the temperature decrease of the heating member at the division surface can be controlled by forming the division surface obliquely with respect to the section perpendicular to the axis.

Further, the present invention is characterized in that the heating member is provided with a good heat conduction layer.

According to the present invention, it is possible to alleviate a temperature rise in a region outside the size when a small-sized recording medium (a material to be heated) is processed.

[0032]

FIG. 1 is a diagram showing an induction heating type fixing device 10 according to a first embodiment of the present invention.
2A is a plan view of the fixing device 10, FIG. 2B is a side view of FIG. 2A, and FIG. 2C is a sectional view taken along line II-II of FIG. 2B. FIG. The fixing device 10 includes a long cylindrical heating roller 11 as a heating member,
It includes a long cylindrical pressure roller 12, an induction coil 15 for heating the heating roller 11, an excitation circuit 16 for supplying an alternating current to the induction coil 14, and a thermistor 17 for detecting the temperature of the heating roller 11.

The heating roller 11 rotates in the direction of arrow A about a rotation shaft 8 extending in a direction perpendicular to the plane of FIG. The pressure roller 12 contacts the heating roller 11 and rotates in the direction indicated by the arrow B. The heating roller 11 and the pressure roller 12
The heating roller 11 is disposed so as to face the recording paper 18.
A contact nip portion is formed between the pressure roller 12 and the pressure roller 12. The induction coil 15 is disposed on the other side of the heating roller 11 opposite to the pressure roller 12 and has a thermistor 17.
Is disposed in contact with the heating roller 11.

The recording paper 18 on which the toner image is formed, which is a material to be heated, passes through a contact nip formed by the heating roller 11 and the pressure roller 12, so that the toner image is heated by heat and pressure. Be established. The heating roller 11
Is provided with a conductive layer 13 that generates heat in an alternating magnetic field, and its outer peripheral surface is covered with a release layer 14. The heating roller 11 is arranged so as to surround one side of the heating roller 11.
An induction coil 15 having a conductive wire wound around both ends in the longitudinal direction is provided. An alternating current corresponding to the temperature of the heating roller 11 detected by a thermistor 17 abutting on the heating roller 11 is applied to the induction coil 15 from an excitation circuit 16. Generates an eddy current, which is heated by electromagnetic induction.

The heating roller 11 includes at least one conductive layer 13 which generates heat by receiving an alternating magnetic field, and a release layer 1 for preventing offset of toner adhering to the heating roller 11.
4 is provided. As the conductive layer 13, a layer having a large relative magnetic permeability is suitable. For example, iron, magnetic stainless steel (for example,
SUS430), a silicon steel plate, an electromagnetic steel plate, a nickel steel, or the like. In addition, even if the material has a low relative magnetic permeability, a material having a high resistivity such as SUS304, which is a non-magnetic stainless steel, may be used because it generates a large amount of heat when an eddy current is generated. Alternatively, a configuration in which the material having a high relative magnetic permeability is provided on a non-magnetic base member such as ceramics so as to have conductivity. In this embodiment, an iron roller (material: STKM) having a diameter of 30 mm and a thickness of 0.4 mm is used for the heating roller 11.

The release layer 14 is coated on the surface of the heating roller 11. For the release layer 14, a fluorine-based material such as PFA (copolymer of tetrafluoroethylene and perfluoroalkylvinyl ether), PTFE (polytetrafluoroethylene), silicon rubber, or fluorine rubber is suitable. In this embodiment, PTFE is set to 2
It is coated with 0 μm.

The induction coil 15 comprises a folded portion 15a at both ends in the longitudinal direction of the heating roller 11 and a portion 15b parallel to the longitudinal direction. The induction coil 15 causes the heating roller 11 to generate heat by eddy current. Therefore, if the induction coil 15 is arranged outside the heating roller 11 as shown in FIG. The magnetic flux is concentrated on the center side, and the amount of eddy current generated can be increased.

Although the induction coil 15 is made of, for example, a single aluminum wire having a surface insulating layer such as an oxide film in consideration of heat resistance, it may be a copper wire or a copper-based composite member wire. Alternatively, a litz wire formed by twisting an enameled wire or the like may be used. Regardless of which wire is used, the total resistance of the induction coil 15 should be 0.5 Ω or less, and preferably 0.5 Ω or less, in order to suppress Joule loss in the coil.
It is better to be 1Ω or less. Although only one induction coil 15 shown in FIG. 2 exists in the longitudinal direction, a plurality of induction coils may be arranged according to the size of the recording paper to be fixed.

The pressure roller 12 is formed on a core metal of iron, stainless steel or aluminum so as to have a heat-resistant elastic layer made of, for example, silicon rubber. Also,
A release layer is formed on the surface. The pressure roller 12
Is pressed against the pressure roller 11 with a force of 100 N by a spring, which is an elastic member (not shown). As a result, the width of the portion in contact with the heating roller 11 becomes 3.5 mm.
A degree of nip is formed.

Next, the fixing operation of the fixing device 10 will be described. First, at the time of warm-up, the excitation circuit 16 connected to the induction coil 15 is turned on, the induction coil 15 is excited, and an AC eddy current is induced in the conductive layer 13 of the heating roller 11 to generate heat by Joule heat. The calorific value at this time is about 800 W. At the same time as the energization by the excitation circuit 16 is started, the heating roller 11 is driven to rotate, so that the pressure roller 12 is driven to rotate. The surface temperature of the heating roller 11 is constantly detected by the thermistor 17, and when the temperature surface of the heating roller 11 reaches a predetermined temperature, the warm-up is completed, and the energization of the induction circuit 15 by the excitation circuit 16 repeats ON-OFF. The control is switched to, and the surface temperature of the heating roller 11 is
It is maintained at a predetermined temperature.

In the fixing device 10 of the present embodiment, the heating roller 11 and the induction coil 15 are formed to have substantially the same length in the longitudinal direction, whereby the heat roller 11 is linked to the conductive layer 13 on the end side. To compensate for the decrease in magnetic flux,
The conducting wire of the turn (turn) portion 15 a of the induction coil 15 on the end side is laminated in a direction perpendicular to the longitudinal direction of the heating roller 11. Thereby, in the section W where the heating roller 11 passes through the induction coil 15, the flux linkage between the end of the heating roller 11 and the other portions can be made substantially equal, and uniform and sufficient heating energy is generated. can do. As a result, although the height direction of the induction coil 15 is slightly increased, the length of the induction coil 15 can be reduced, and the length H of the straight portion 15b parallel to the heating roller 11 can be increased to increase the length. The straight portion 15b can be widely used.

FIG. 3 is a diagram showing an electrophotographic color image forming apparatus 100 which is an application example of the fixing device 10. The color image forming apparatus 100 is a so-called tandem type printer in which four color visible image forming units 110Y, 110M, 110C, and 110B are arranged along a recording medium conveyance path. Specifically, the recording paper supply tray 101
Along the conveyance path of the recording paper 18 connecting the paper and the fixing device 10,
Four sets of visible image forming units 110Y, 110M, 110
C, 110B, and a recording paper conveying means 1 for an endless belt.
After the toners of each color are multiply transferred onto the recording paper 18 conveyed by the printer 02, the fixing device 10 fixes the toners to form a full-color image. Recording transport means 102
Is stretched by a pair of drive rollers 103 and an idling roller 104 and has a predetermined peripheral speed (1 in this embodiment).
It has an endless transport belt 105 which rotates at a controlled speed of 34 mm / s. The recording paper 18 is electrostatically attracted onto the belt and transported. Each visible image forming unit 110Y, 1
10C, 110M, and 110B are provided around a photosensitive drum 111 around a charging roller 112, a laser beam irradiation unit 113,
Developing device 114, transfer roller 115, and cleaner 11
6 are arranged, and Y (yellow), M (magenta), C (cyan), B
(Black) toners are respectively stored. Each visible image forming unit 110Y, 110M, 110C, 1
10B forms a toner image on the recording paper 18 by the following steps.

That is, after the surface of the photosensitive drum 111 is uniformly charged by the charging roller 112, the laser beam irradiating means 1
By 13, the surface of the photosensitive drum 111 is exposed to a laser beam according to the image information to form an electrostatic latent image. Thereafter, a toner image is formed on the electrostatic latent image on the photosensitive drum 111 by the developing device 114, and the developed toner image is transferred to the transfer roller 11 to which a bias voltage having a polarity opposite to that of the toner is applied.
5, the recording paper 1 transported by the recording paper transporting means 102
8 are sequentially transferred.

After that, the recording paper 18 is separated from the transport belt 105 by the curvature of the driving roller 103 and then transported to the fixing device 10. Therefore, as described above, the heating roller 11 and the pressure roller 12 maintained at a predetermined temperature are used.
Provides a moderate temperature and pressure. The toner dissolves and is fixed to the recording paper 18, resulting in a robust image.

FIG. 4 is a plan view of a part of a fixing device 120 according to a second embodiment of the present invention. Members common to those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. The induction coil 31 includes a folded portion 31a at both ends in the longitudinal direction of the heating roller 11 and a portion 31b parallel to the longitudinal direction. In the fixing device 120 of the present embodiment, the loop diameter of the induction coil 31 at the end side is enlarged to compensate for the decrease in the flux linkage to the conductive layer 13 at the end of the heating roller 11. Turning. That is, the induction coil 3
The interval M1 in the circumferential direction of the heating roller 11 in the first folded portion 31a is made longer than the interval M2 of the linear portion 31b, so that the time for the end of the heating roller 11 to pass through the induction coil 31 is increased. The flux linkage between the part and the other part is almost equal. Thereby, without changing the height, the adjustment in the two-dimensional direction by enlarging the loop diameter of the folded portion at both ends in the longitudinal direction of the heating roller 11, that is,
By adjusting the width of the heating roller 11 in the circumferential direction at the center and the end, the passage time of the conductive layer 13 in the interlinkage magnetic flux can be increased, so that the heating roller 11 can be uniformly heated.

FIG. 5A is a plan view of a part of a fixing device 130 according to a third embodiment of the present invention, and FIG. 5B is a side view of FIG. 5A. Members common to those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted. The induction coil 33 includes a folded portion 33a at both ends in the longitudinal direction of the heating roller 11 and a portion 33b parallel to the longitudinal direction. Induction coil 33 of fixing device 130 of the present embodiment
As in the conventional induction coil 4 shown in FIG. 22, at the end of the heating roller 11, a conductive wire is wound on the same plane as the longitudinal direction of the heating roller 11. Therefore, the heating roller 1
In order to compensate for the decrease in the flux linkage to the conductive layer 13 at the end of the first conductive layer 32, the second conductive layer 32
Is provided.

The second conductive layer 32 is formed by plating, for example, and is made of a material having the same or higher relative magnetic permeability μ _r as the conductive layer 13. Thereby, the second conductive layer 3
2, the magnetic flux density in the area 2 is increased, the generated eddy current is increased, and the amount of generated heat is also increased.

Alternatively, the second conductive layer 32 is made of a material having a higher volume resistivity ρ than that of the conductive layer 13, and the amount of heat generated at the same current value is increased. In this case, the conductive layer 13
Is made of, for example, STKM steel, μ _r = 100, and the volume resistivity ρ is 10 ⁻⁵ Ωcm or less, whereas the second conductive layer 32 is made of, for example, SUS430, and μ _r =
100, ρ = 6 × 10 ⁻⁵ Ωcm. Other, as relative permeability mu _r and the volume resistivity ρ is large material, such as silicon steel, etc. oriented silicon steel or Al-Fe alloy may be used.

FIG. 6A is a plan view of a fixing device 140 according to a fourth embodiment of the present invention, and FIG.
It is sectional drawing seen from the cutting surface line VI-VI of (a). The same reference numerals are given to members common to the above-described embodiment, and description thereof will be omitted. The fixing device 140 according to the present embodiment is arranged such that, in order to compensate for the decrease in the interlinkage magnetic flux with the conductive layer 13 at the end of the heating roller 11, the end of the induction coil 33 at the end in the longitudinal direction of the heating roller 11 is A heat conducting member 35 provided with a plurality of magnetic members 34 arranged in a direction perpendicular to the conducting wire of the coil, that is, parallel to the generated magnetic field, is provided near the folded portion 33a of the portion.

The heat conducting member 35 is made of a material having a high thermal conductivity, for example, aluminum or copper.
Is transmitted to the heating roller 11 by radiation. In addition, the magnetic member 34 is the second member of the third embodiment.
SUS430 of the same material as the conductive layer 32, silicon steel, Al-Fe alloy, or the like. By bringing the magnetic member 34 close to the induction coil 33, the linkage density that links the magnetic member 34 increases. The generated eddy current can be increased.

As described above, the magnetic member 34 efficiently captures the magnetic flux, the eddy current generated in the magnetic member 34 is large, the amount of generated heat is increased, and the generated heat is uniformly spread by the heat conductive member 35. It will be radiated to the heating roller 11.

The configurations of the fixing devices 10, 120, 130, and 140 of the first to fourth embodiments may be used in any combination. The present invention can also be applied to a heating device such as an apparatus, a drying device in an ink jet printer, or an erasing device for rewritable media.

FIG. 7A is a cross-sectional view in the axial direction of the heating roller 11 for explaining the magnetic shield for blocking the magnetic field generated by the induction coils 15, 31, 33 of the first to fourth embodiments. FIG. 7B is a cross-sectional view in the axial direction. Although FIGS. 7A and 7B show the induction coil 15 as an example, the invention can be similarly applied to the induction coils 31 and 33. The shield member 36 is formed by covering both ends of a semi-cylindrical cylindrical portion 36 a with end plates 36 b so as to cover the induction coil 15. The shield member 36 is formed by bonding an outer member 37 and an inner member 38 made of resin or the like, and enclosing a magnetic fluid 39 in an inner space thereof.

At a portion where the leakage magnetic flux is large, the height of the internal space is formed high so that the amount of the magnetic fluid increases. The magnetic fluid 39 includes magnetite (Fe ₃ O ₄ )
A colloidal solution is used in which fine particles (about 10 nm) of a ferromagnetic material, such as manganese or Mn-Zn composite ferrite, are dispersed in a liquid such as water, hydrocarbon oil or fluorine oil via a surfactant or the like. Can be Thereby, the magnetic shield can be realized in an arbitrary shape along the shape of the induction coil 15.

FIG. 8 is a diagram showing a fixing device 150 according to a fifth embodiment of the present invention. FIG. 9A is a plan view of the fixing device 150 of FIG. 8, and FIG. 8 fixing device 1
It is a side view of 50. Members common to the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In the fixing device 150 of this embodiment, the magnetic member 20 is provided on the side of the induction coil 25 opposite to the heating roller 11.
Is arranged. The magnetic member 20 is connected to the induction coil 2.
5 and in the longitudinal direction of the induction coil 25,
It is divided into a plurality as shown by reference numerals 20a, 20b and 20c. The magnetic members 20b and 20c are
As a result, it is displaced toward and away from the induction coil 25. Further, the induction coil 25 extends in parallel with the longitudinal direction of the heating roller 11 so as to surround one of the heating rollers 11, and is folded at both ends of the heating roller 11, thereby forming the induction coil of the first embodiment. It is made of the same material as No. 15.

The magnetic member 20a and the induction coil 25
Is attached to a support member, not shown. The magnetic members 20b and 20c are also attached to a support member (not shown) separate from the magnetic member 20a and the induction coil 25. The support member has insulation and heat resistance, for example, PPS (polyphenyl sulfide), PI (polyimide), ceramic, PTFE
(Polytetrafluoroethylene), a silicon-based / urethane-based sponge (foam), or a nonwoven fabric or a glass wool made of an amide-based or aramid-based heat-resistant fiber having a laminated structure.

The magnetic member 20 is preferably made of a material having a higher magnetic permeability than that of the heating roller 11, and is made of, for example, ferrite (nickel-manganese or manganese-ferrite), silicon steel sheet, electromagnetic steel sheet, or the like. If there is conductivity, an eddy current is generated in that portion, so that it is formed by sintering or formed into a laminated structure.

FIG. 10 shows the heating roller 1 of the fixing device 150.
FIG. 2 is a diagram for explaining temperature characteristics of No. 1; When the recording paper 18 has a large size, as shown by a solid line in FIG.
Ob and 20c are also brought close to the induction coil 25. Thereby, as shown by the solid line in FIG. 10B, uniform temperature characteristics can be obtained over the entire length of the heating roller 11.

On the other hand, when the recording paper 18 is of a small size, the displacement members 21 move the magnetic members 20b, 20b to a position indicated by a broken line in FIG.
c is separated from the induction coil 25, and only the magnetic member 20a is close to the induction coil 25. As a result, as shown by the broken line in FIG. 10B, only the central portion of the heating roller 11 facing the magnetic member 20a has a uniform high temperature, and the temperature at both ends decreases as the distance from the central portion decreases. Go on.

Therefore, even if the fixing process is performed on the small-sized recording paper, the heat storage at both ends of the heating roller 11 does not cause an undesired rise in temperature. There is no occurrence of a fixing defect such as the high-temperature offset. Further, it can be realized with a simple configuration in which the magnetic members 20b and 20c are selectively displaced toward and away from the magnetic field generating means.

In addition, a relatively long magnetic member 20a is divided into a plurality of relatively short magnetic members 20b and 20c.
By using in combination, cracks in the temperature of the surface of the heating roller 1 are less likely to occur, and the yield can be improved.

Further, since the magnetic flux can be efficiently concentrated on the heating roller 11 by the magnetic member 20, the distance between the heating roller 11 and the induction coil 25 can be increased. Therefore, the induction coil 25 is
Can be made less susceptible to heat. This makes it possible to lower the ambient temperature of the induction coil 25, prevent an increase in coil resistance, and improve the heating efficiency.

The sheet 18 with respect to the displacement means 21
In the case where the fixing device 150 is used in a copying machine, for example, the size detection can be realized by a paper size selection signal from an operation panel or a paper detection signal (optically detected) from a document table or a manual feed tray. When used in a printer, it can be realized by a paper size signal from a host computer.

The magnetic member 20a and the induction coil 25
Are attached to a fixed support member. On the other hand, the magnetic members 20b and 20c
a and a movable support member separate from the induction coil 25, and is displaced toward and away from the induction coil 25 by a displacement means. The support member is made of a material having insulation and heat resistance.

FIGS. 11A and 11B are views showing a displacement means 40 which is a specific example of the structure of the displacement means 21. FIG. FIG. 11A is a front view of the displacement unit 40, and FIG. 11B is a plan view of the displacement unit 40. Although only the magnetic member 20b is shown in the displacement means 40 of the present embodiment, a similar configuration is used for the magnetic member 20c.

In the displacement means 40, the magnetic member 20a is attached to a fixed support member 41. On the other hand, the magnetic member 20b is attached to the support member 42. A driving piece 43 extends radially outward of the heating roller 11 from an edge of the support member 42.
A ball screw 45 engraved on the rotation shaft of the motor 44 is screwed into the screw hole 3 and the support member 42, that is, the magnetic member 20 b is rotated by the motor 44. Can be displaced in the direction of the axis. Thus, the magnetic member 20b can be displaced toward and away from the induction coil 25.

FIG. 12 is a front view of a displacement means 50 which is another specific example of the construction of the displacement means 21. As shown in FIG. Although only the magnetic member 20b is shown in the displacement means 50 of this embodiment, a similar configuration is used for the magnetic member 20c.

In the displacement means 50, the magnetic members 20b and 20c are attached to the support member 53. The support member 53 is connected via an arm 51 to a pinion gear 52 having a rotation axis in the axial direction of the heating roller 11, and the pinion gear 52 is driven by a rack gear (not shown), whereby the support member 53 is driven. Therefore, the magnetic members 20b and 20c are swingably displaceable in a plane perpendicular to the axis of the heating roller 11 indicated by the arrow 54. Thus, the magnetic members 20b and 20
c is displaced toward and away from the induction coil 25 in a plane perpendicular to the axis of the heating roller 11, so that the apparatus is displaced in the axial direction of the heating roller 11 as shown by the displacement means 40. Miniaturization can be realized.

FIG. 13 is a front view of a displacement means 60 which is another specific example of the displacement means 21. Although only the magnetic member 20b is shown in the displacement means 60 of this embodiment, the same configuration is used for the magnetic member 20c.

In the displacement means 60, the support member 63
The induction member 25, which is formed in an arc shape parallel to the outer peripheral surface of the heating roller 11, and a rack gear 61 formed at one end in the circumferential direction is driven by a pinion gear 62 so that the magnetic members 20 b and 20 c The heating roller 11 can be displaced in a plane perpendicular to the axis of the heating roller 11 indicated by the arrow 64 and in the circumferential direction of the heating roller 11.

FIG. 14 is a front view of a displacement means 70 which is still another specific example of the displacement means 21. As shown in FIG. Although only the magnetic member 20b is shown in the displacement means 70 of this embodiment, a similar configuration is used for the magnetic member 20c.

In the displacement means 70, the support member 73
An induction coil 25, that is, an arc shaped parallel to the outer peripheral surface of the heating roller 11, is formed with a screw hole formed at the center in the circumferential direction, and a ball screw 72 engraved on the rotation shaft of the motor 71 is screwed. When the motor 71 is driven to rotate, the support member 73 and thus the magnetic members 20b and 20c can be displaced in the radial direction of the heating roller 11 as indicated by an arrow 74.

FIG. 15 is a front view of a displacement means 80 which is another concrete example of the displacement means 21. As shown in FIG. Although only the magnetic member 20b is shown in the displacement means 80 of this embodiment, a similar configuration is used for the magnetic member 20c.

In the displacement means 80, the support member 83
Like the displacement means 70, the induction coil 25 is formed in an arc shape parallel to the outer peripheral surface of the heating roller 11,
An operating piece of the solenoid 81 and one end of a tension spring 82 are fixed to a central portion in the circumferential direction. In the displacement means 80, when the solenoid 81 is not driven, the support member 83, and thus the magnetic members 20b and 20c,
Is close to the heating roller 11 due to the resilience of the heating roller 11, and when driven, separates from the heating roller 11 in the radial direction against the resilience.

FIG. 16 is a front view of a displacement means 90 which is still another specific example of the displacement means 21. Although only the magnetic member 20b is shown in the displacement means 90 of this embodiment, a similar configuration is used for the magnetic member 20c.

In the displacement means 90, the support member 93
As with the displacement means 70 and 80, the induction coil 25
That is, it is formed in an arc shape parallel to the outer peripheral surface of the heating roller 11, and one end in the circumferential direction is supported by a shaft 91 parallel to the axis of the heating roller 11 so as to be swingably displaceable. When the extended operating piece 92 is driven by the cam 94 and the tension spring 95, the magnetic member 2
0b is displaceable in a plane perpendicular to the axis of the heating roller 11 as indicated by an arrow 96.

FIG. 17 is a diagram showing an electrophotographic color image forming apparatus 160 which is an application example of the fixing device 150. The color image forming apparatus 160 has substantially the same configuration as the color image forming apparatus 100 using the fixing device 10 of the first embodiment, and the fixing device 10 of the color image forming apparatus 100 is replaced with the fixing device 150 of the present embodiment. Therefore, the description of the color image forming apparatus 160 is omitted.

The configuration of the fixing device 150 of the present embodiment is the same as that of the fixing devices 10, 120, 1 of the first to fourth embodiments.
Any of the configurations 30 and 140 may be used in combination.

FIG. 18 is a view for explaining temperature characteristics of a heating roller of a fixing device using the magnetic members 20a1, 20b1, 20c1 according to the sixth embodiment of the present invention. The fixing device of this embodiment has the same configuration as the fixing device 150 of the fifth embodiment, and differs only in the shape of the magnetic member.
FIG. 18A shows the magnetic member 20a of the fifth embodiment,
18B is a diagram showing a cross section of 20b, 20c, FIG. 18B is a diagram showing a cross section of the magnetic members 20a1, 20b1, 20c1 of the present embodiment, and FIG. 18C is a diagram of FIG. It is a figure which shows the temperature distribution of the heating roller heated using the magnetic member of 18 (b). The magnetic members 20a, 20b used in the fixing device 150 according to the fifth embodiment,
As shown in FIG. 18A, the division surface 20c is formed in parallel with the cross section of the heating roller 11 perpendicular to the axis. For this reason, when the magnetic members 20b and 20c are used close to the induction coil 15 and the entire length of the magnetic members 20a, 20b and 20c is used, as shown by a broken line in FIG. The magnetic flux does not concentrate in the gap between the magnetic members 20b and between the magnetic members 20b and 20c, and the temperature is reduced.

On the other hand, the magnetic member 2 shown in FIG.
As shown by 0a1, 20b1, and 20c1, when the division surface is formed so as to intersect with the section perpendicular to the axis of the heating roller 11, as shown by a solid line in FIG. , 20b1,2
A uniform temperature characteristic can be obtained over the entire length of 0c1.

FIG. 19A shows the state of the magnetic members 20a1 and 20a1.
It is a figure which shows the example of a dimension of 20b1, 20c1. The magnetic member 20a1 is referred to as a core 20B, and the magnetic members 20b and 20c are referred to as a core 20A. L1 is the entire length of the magnetic member, a1 is the length of one end surface (upper surface in FIG. 19A) of the core 20A in a direction perpendicular to the longitudinal direction of the heating roller 11, and c1 is the heating roller 11 of the core 20A. The length of the other end surface (the lower surface in FIG. 19A) in the direction perpendicular to the longitudinal direction of
Represents the length of one end face of the heating roller 11 in the direction perpendicular to the longitudinal direction, and d1 represents the length of the other end face of the core 20B in the direction perpendicular to the longitudinal direction of the heating roller 11. In this embodiment, L1
= 310 mm, a1 = 45 mm, b1 = 220 mm, c
When 1 = 40 mm and d1 = 230 mm, and these settings are made, by displacing the core 20A, it is possible to adapt to various recording paper sizes as shown in Table 1.
Table 1 shows the cores used depending on the paper size.

[0083]

[Table 1] * Paper size A3: 297mm × 420mm A4: 210mm × 297mm A5: 149m
m × 210mm B4: 261mm × 363mm B5: 181mm × 261mm

FIG. 19B is a diagram showing an arrangement of a thermistor for detecting the temperature of the heating roller when the magnetic member is formed as shown in FIG. 19A. The thermistor is disposed at positions P2 and P3 in addition to the reference position P1 in order to detect a temperature rise at the periphery of the recording paper. The widths A5, B5, and B4 in FIG.

The displacement means for displacing the magnetic members 20b1 and 20c1 toward and away from the induction coil 25 is the displacement means 40, 50, 60, 70 and 8 of the fifth embodiment.
0,90 can be used. The configuration of the fixing device of the present embodiment is the same as that of the fixing device 1 of the first to fourth embodiments.
It may be used in any combination with the configurations of 0, 120, 130, and 140.

FIG. 20A is a view showing examples of shapes and dimensions of the magnetic members 30a and 30b used in the fixing device according to the seventh embodiment of the present invention. The fixing device of the present embodiment has the same configuration as the fixing device 150 of the fifth embodiment, and differs only in the shape of the magnetic member. The magnetic member 30a
Is a core 30B, and the magnetic member 30b is a core 30A. L
2 is the entire length of the magnetic member, a2 is the length of one end surface (upper surface in FIG. 20A) of the core 30A in a direction perpendicular to the longitudinal direction of the heating roller, and c2 is the length of the heating roller of the core 20A. The length of the other end surface in the direction perpendicular to the direction (the lower surface in FIG. 20A), b2 is the length of one end surface of the core 30B in the direction perpendicular to the longitudinal direction of the heating roller 11, and d2 is the length of the core 30B. The length of the other end surface in a direction perpendicular to the longitudinal direction of the heating roller 11 is shown. In this embodiment, L2 = 310 mm, a2 = 90 m
m, b2 = 220 mm, c2 = 80 mm, d2 = 230
mm.

The magnetic members 20a, 20b, 20c and the magnetic members 20a1, 20a of the fifth and sixth embodiments are described.
b1 and 20c1 convey the recording paper 18 with reference to the center line position in the width direction of the recording paper 18, and the magnetic member is divided into three in the longitudinal direction of the heating roller. The recording paper is conveyed based on one end in the longitudinal direction, and the magnetic member is divided into two in the longitudinal direction. In the magnetic members 30a and 30b, the sixth
Similarly to the magnetic members 20a1, 20b1 and 20c1 of the embodiment, when the dimensions are set as described above, by displacing the magnetic member 30b, various types of recording paper as shown in Table 2 are obtained. Can adapt to size. Table 2 shows the cores used depending on the paper size.

[0088]

[Table 2] * Paper size A3: 297mm × 420mm A4: 210mm × 297mm A5: 149m
m × 210mm B4: 261mm × 363mm B5: 181mm × 261mm

FIG. 20B is a view showing the arrangement of a thermistor for detecting the temperature of the heating roller when the magnetic member is formed as shown in FIG. 20A. The thermistor is disposed at positions P12 and P13 in order to detect a temperature rise at the peripheral portion of the recording paper, in addition to the center position P11 of the small-sized recording paper, as shown in FIG. Based on the temperature detection result, after printing is completed, the heating roller 11 and the pressure roller 12 are idled until they reach a predetermined temperature.

The magnetic material 30b is connected to the induction coil 25.
The displacing means 21 for performing the displacing / separating movement from the displacing means 40, 50, 60, 70, 80, 90 of the fifth embodiment can be used. Further, the configuration of the fixing device of the present embodiment is the same as that of the fixing devices 10, 120,
Any combination with the configuration of 130 and 140 may be used.

The number of divisions of the magnetic member may be appropriately determined according to the size of the recording paper to be adapted.
Since the drive control by the displacement means 21 becomes complicated, it may be set to about two or three by taking measures against the temperature rise in the area outside the size when processing small-sized recording paper.

FIG. 21 is a sectional view of a heating roller 11a, which is another example of the configuration of the heating roller 11. As shown in FIG. In the heating roller 11a, between the conductive layer 13 and the release layer 14,
A good thermal conductive layer 99 made of aluminum, copper, or the like and having a low magnetic permeability and a good conductor is provided. When the number of divisions of the magnetic member is reduced to about two or three as in the fifth to seventh embodiments, the temperature of the region outside the size during processing of a small-sized recording sheet is improved by the good heat conducting layer 99. The rise can be mitigated.

[0093]

According to the present invention, the conductor of the induction coil folded back at the end of the heating member is laminated and wound in a direction perpendicular to the longitudinal direction of the heating member, so that the apparatus is not enlarged. Even if the longitudinal lengths of the heating member and the induction coil are formed substantially equal, the linear portion of the induction coil can be widely used, and the heating member generates heat uniformly over the entire length, and has a simple configuration. Temperature unevenness can be eliminated.

Further, according to the present invention, the loop diameter of the induction coil that is folded back at both ends of the heating member is enlarged, and two-dimensional adjustment is performed, that is, the width is larger at the end than at the center of the induction coil. By adjusting, the transit time of the conductive layer in the interlinkage magnetic flux is increased, so that the length of the heating member and the induction coil in the longitudinal direction are substantially equal so that the device is not enlarged, even if the heating member is formed. Heat is generated uniformly over the entire length, and with a simple configuration, temperature unevenness can be eliminated.

Further, according to the present invention, a second conductive layer is provided at the end of the heating member, and the second conductive layer is formed from a material having a higher relative magnetic permeability or volume resistivity than the conductive layer. In addition, heat is efficiently generated even with a small amount of interlinkage magnetic flux. by this,
Even if the lengths of the heating member and the induction coil in the longitudinal direction are substantially equal so that the apparatus is not increased in size, the heating member generates heat uniformly over the entire length, and can have a simple configuration to eliminate temperature unevenness.

Further, according to the present invention, a plurality of magnetic members orthogonal to the conductor of the induction coil, that is, parallel to the generated magnetic flux are arranged near the loop portion of the induction coil which is folded at both ends of the heating member. By providing the heat conducting member, the magnetic member efficiently captures the magnetic flux, the eddy current generated in the magnetic member increases greatly, and the amount of heat generated increases. Even if the lengths in the directions are substantially equal, it is possible to generate heat uniformly over the entire heating member, and it is possible to eliminate temperature unevenness with a simple configuration.

According to the present invention, the magnetic member provided adjacent to the induction coil is divided into a plurality of pieces in the longitudinal direction, and only the magnetic member facing the portion is brought close to the induction coil according to the size of the material to be heated. Therefore, the magnetic member divided into a plurality of parts can be selectively moved toward and away from the induction coil by a simple configuration. The heating member can be heated evenly, and the heating member can be heated uniformly without temperature unevenness.

Also, since the magnetic member allows the magnetic flux to be efficiently concentrated on the heating member, the distance between the heating member and the induction coil can be increased. That is, since the induction coil can be made less susceptible to the influence of the temperature of the heating member, it is possible to prevent the resistance of the coil from increasing by lowering the ambient temperature and improve the heating efficiency.

Further, since the induction coil is disposed so as to surround the heating member, if the heating member is a heating roller,
The induction coil, which is the magnetic field generating means, is disposed outside the heating member with a curvature, and has an effect that the effect of concentrating magnetic flux on the heating member is large. You can focus.

Further, according to the present invention, by forming the divided surface of the magnetic member obliquely with respect to the section perpendicular to the axis of the heating member, it is possible to suppress a decrease in the temperature of the heating roller at the divided surface.

Further, according to the present invention, it is possible to alleviate a temperature rise in an area outside the size when a small-sized recording medium is processed.

[Brief description of figures]

FIG. 1 is a diagram showing an induction heating type fixing device 10 according to an embodiment of the present invention.

2A is a plan view of the fixing device 10 of FIG. 1, and FIG. 2B is a side view of the fixing device 10 of FIG.
(C) is a cross-sectional view taken along line II-II in (b).

FIG. 3 is a diagram illustrating an electrophotographic color image forming apparatus 100 in which the fixing device 10 of FIG. 1 is used.

FIG. 4 is a diagram illustrating a fixing device 120 according to a second embodiment of the present invention.

FIG. 5A is a plan view of a fixing device 130 according to a third embodiment of the present invention, and FIG. 5B is a side view of FIG.

FIG. 6A is a plan view of a fixing device 140 according to a third embodiment of the present invention, and FIG. 6B is a sectional view taken along line V in FIG.
It is sectional drawing seen from I-VI.

7A is a cross-sectional view of a magnetic shield of a magnetic field generated by an induction coil 15 in the axial direction of a heating roller 11, and FIG. 7B is a cross-sectional view of FIG. is there.

FIG. 8 is a diagram illustrating a fixing device 150 according to a fifth embodiment of the present invention.

9A is a plan view of the fixing device 150 of FIG. 8, and FIG. 9B is a side view of the fixing device 150 of FIG.

FIG. 10A is a diagram showing the approach and separation of magnetic members 20a, 20b, and 20c of the fixing device 150 of FIG.
(B) is a diagram showing the temperature characteristics of the heating roller 11 corresponding to (a).

FIGS. 11A and 11B are views showing a displacement unit 40 which is a specific configuration example of the displacement unit.

FIG. 12 shows a displacement unit 5 which is a specific configuration example of the displacement unit.
FIG.

FIG. 13 shows a displacement unit 6 as a specific configuration example of the displacement unit.
FIG.

FIG. 14 shows a displacement unit 7 as a specific configuration example of the displacement unit.
FIG.

FIG. 15 shows a displacement unit 8 which is a specific configuration example of the displacement unit.
FIG.

FIG. 16 shows a displacement unit 9 as a specific configuration example of the displacement unit.
FIG.

17 is a diagram illustrating an electrophotographic color image forming apparatus 160 in which the fixing device 150 of FIG. 8 is used.

18A is a diagram illustrating magnetic members 20a, 20b, and 20c of the fixing device 150 of FIG. 8, and FIG. 18B is a diagram illustrating a magnetic member used in a fixing device according to a sixth embodiment of the present invention. It is a figure which shows 20a1, 20b1, 20c1, (c)
FIG. 4 is a diagram illustrating temperature characteristics of a heating roller corresponding to FIGS.

FIG. 19A is a diagram illustrating the magnetic member 20a of FIG.
It is a figure which shows the example of a dimension of 1,20b1,20c1,
(B) is a figure which shows the example of arrangement | positioning of the thermistor in the case of (a).

FIG. 20A is a diagram illustrating an example of dimensions of magnetic members 30a and 30b used in a fixing device according to a seventh embodiment of the present invention, and FIG. 20B is a diagram illustrating a thermistor in the case of FIG. It is a figure showing an example of arrangement.

FIG. 21 is a view showing a heating roller 11a as another configuration example of the heating roller 11.

FIG. 22A illustrates a conventional fixing device 170.
(B) is a side view thereof, and (c) is a plan view thereof.
FIG. 2 is a cross-sectional view taken along the line II of FIG.

FIG. 23 is a diagram showing a fixing device 200 according to a conventional technique.

24 is a perspective view of induction coils 209a, 209b, and 209c in the fixing device 200 of FIG.

[Explanation of symbols]

10, 120, 130, 150, 170, 200 Fixing device 1, 11, 11a, 201 Heating roller 2, 12, 202 Pressing roller 4, 15, 25, 31, 33 Induction coil 13 Conductive layer 14 Release layer 16 Excitation Circuit 17 Thermistor 18,216 Recording paper 20,34 Magnetic member 21,40,50,60,70,80,90 Displacement means 32 Second conductive layer 35 Heat conductive member 99 Good heat conductive layer 100,160 Color image forming apparatus

Continued on the front page F term (reference) 2C056 EA23 EB13 EB14 EB30 EB46 EC14 EC29 EC33 EC35 HA46 2H033 AA03 AA21 AA30 BA25 BA27 BB21 BB23 BE06 CA17 CA48 3K059 AA08 AB19 AB28 AD03 AD05 AD37 CD52 CD53 CD65 CD66 CD75 CD78 CD78

Claims (7)

[Claims] 1. A heating device comprising: a longitudinal heating member having a conductive layer that generates heat in an alternating magnetic field; and a conducting wire that extends parallel to the longitudinal direction of the heating member and is folded at both longitudinal ends and wound. An induction coil disposed so as to surround one side of the member, wherein the alternating magnetic field from the induction coil heats the heating member by electromagnetic induction, and the other side of the heating member opposite to the induction coil is heated. In an induction heating apparatus for transmitting heat of a heating member to a material to be provided, the heating member and the induction coil are formed so that the lengths in the longitudinal direction are substantially equal to each other. An induction heating apparatus characterized in that an induction coil at the end is laminated and wound in a direction perpendicular to the longitudinal direction of the heating member in order to compensate for a reduction in linkage magnetic flux. 2. A heating device comprising: a longitudinal heating member having a conductive layer that generates heat in an alternating magnetic field; and a conducting wire extending parallel to the longitudinal direction of the heating member and folded at both ends in the longitudinal direction. An induction coil disposed so as to surround one side of the member, wherein an alternating magnetic field from the induction coil heats the heating member by electromagnetic induction, and the other side of the heating member opposite to the induction coil is heated. In an induction heating device for transmitting heat of a heating member to a material to be provided, the heating member and the induction coil are formed so that the lengths in the longitudinal direction are substantially equal to each other. An induction heating device characterized in that a loop diameter of an induction coil that is turned back at the end side is enlarged and wound in order to compensate for a decrease in interlinkage magnetic flux. 3. A heating device comprising: a longitudinal heating member provided with a conductive layer that generates heat in an alternating magnetic field; and a conducting wire extending parallel to the longitudinal direction of the heating member and folded at both longitudinal ends to be wound. An induction coil disposed so as to surround one side of the member, wherein an alternating magnetic field from the induction coil heats the heating member by electromagnetic induction, and the other side of the heating member opposite to the induction coil is heated. In an induction heating device for transmitting heat of a heating member to a material to be provided, the heating member and the induction coil are formed so that the lengths in the longitudinal direction are substantially equal to each other. A second conductive layer is provided at the end in order to compensate for a decrease in linkage flux, and the second conductive layer is formed of a material having a higher relative magnetic permeability or volume resistivity than the conductive layer. Induction heating device characterized by the following 4. A heating element comprising a longitudinal heating member having a conductive layer that generates heat in an alternating magnetic field, and a conductive wire extending in parallel with the longitudinal direction of the heating member and folded at both ends in the longitudinal direction and wound. An induction coil disposed so as to surround one side of the member, wherein an alternating magnetic field from the induction coil heats the heating member by electromagnetic induction, and the other side of the heating member opposite to the induction coil is heated. In an induction heating device for transmitting heat of a heating member to a material to be provided, the heating member and the induction coil are formed so that the lengths in the longitudinal direction are substantially equal to each other. An induction heating apparatus characterized in that a heat conducting member that is subjected to electromagnetic induction heating is provided at a turn-back portion of the induction coil on the end side in order to compensate for a reduction in linkage flux. 5. A heating device comprising: a longitudinal heating member having a conductive layer that generates heat in an alternating magnetic field; and a conducting wire extending parallel to the longitudinal direction of the heating member and folded at both longitudinal ends to be wound. An induction coil disposed so as to surround one side of the member, wherein an alternating magnetic field from the induction coil heats the heating member by electromagnetic induction, and the other side of the heating member opposite to the induction coil is heated. An induction heating device for transmitting heat of a heating member to an object to be provided, which is disposed along the induction coil and is divided into a plurality of parts in a longitudinal direction of the induction coil, and a part or all of the part is the object to be heated. An induction heating device comprising: a magnetic member that moves toward and away from the induction coil according to the size of the induction coil. 6. The magnetic member according to claim 5, wherein a division surface of the magnetic member intersects a cross section perpendicular to an axis of the heating member.
An induction heating device as described. 7. The induction heating apparatus according to claim 5, wherein the heating member is provided with a good heat conduction layer.