JPH0816006A - Heating apparatus and image forming apparatus - Google Patents

Abstract

PURPOSE:To carry out stable heating treatment for a material to be heated by preventing overheating phenomenon in a region where no paper passes and uniformalizing the heat radiation distribution in a region where a paper passes regading an electromagnetic induction heating-type heating apparatus. CONSTITUTION:A heating apparatus is electromagnetic induction heating-type wherein a magnetic field is made to act on a conductive member which is either fixed or movable to generate eddy current in the conductive member and a material to be heated which is conveyed while being brought into contact directly or indirectly with the conductive member is heated by heat generation in the conductive member due to the eddy current. The apparatus is mad so as to have characteristics that magnetic field generating means 2, 3 is divided into 2a, 3a, 2b, 3b, 2c, 3c in the direction at right angles to the conveying direction of the material to be heated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating device of an electromagnetic (magnetic) induction heating system, and an image forming apparatus provided with the heating device as an image heating and fixing device.

[0002]

2. Description of the Related Art In recent years, due to the trend of energy saving in office automation equipment, an image heating and fixing device as a heating device used in printers, copiers, etc., has a conventional general heat roller in order to achieve both energy saving and quick start property. A film heating type fixing device has been partially put into practical use in the field of low-speed machines instead of the fixing device of the type.

A film heating type apparatus is disclosed in JP-A-63-3.
13182, JP-A-2-157878, JP-A-4-44075, JP-A-4-204980. That is, it has a heating body (generally referred to as a ceramic heater, hereinafter referred to as a heater) and a heat-resistant film that moves in close contact with the heater. Is a heating device for moving the heat source to apply the heat energy of the heater to the object to be heated through the film. It has a pressurizing member that brings the film and the object to be heated into close contact with the heater.

In the image fixing operation, a recording material as a heated body is introduced and passed between a film and a pressing member in a fixing nip portion formed by pressing a heater and a pressing member with the film interposed therebetween. The heating is performed by heating the surface of the recording material on which the developed image is carried with a heater through a film to apply thermal energy to the unfixed toner image to soften and melt the toner.

Further, not limited to the fixing device, for example, a device for heating a recording material carrying an image to modify the surface property such as gloss, a hypothetical fixing device, and other various means for heat-treating the heating material. -Can be used as a device.

In such a film heating type apparatus,
Since a heater having a low heat capacity can be used, the wait time can be shortened (quick start) as compared with the heat roller method. Further, since the quick start is possible, it is not necessary to raise the temperature of the heater in advance, so that it is possible to reduce the power consumption and prevent the temperature rise inside the machine.

However, in order to increase the speed of such a film heating type apparatus as well, it is necessary to increase the thickness of the film. In that case, the thick film becomes a thermal resistance and the material to be heated from the heater. The heat transfer to a certain recording material is significantly impaired, and the energy saving and quick start characteristics, which are the features of the film heating system, are impaired.

Therefore, the inventors of the present invention have conducted research on a heating device of an electromagnetic induction heating system / film heating system in which the film itself does not generate heat resistance by heating the film itself and the thermal efficiency is improved.

This is a conductive member (inductive magnetic material, magnetic field absorbing conductive material) that moves in the magnetic field by changing the magnetic field generated by a magnetic field generating means, for example, a core material which is a magnetic material and a coil, in an exciting circuit. ), Which generates an eddy current in the conductive layer in the film. This eddy current is converted into heat (Joule heat) by the electric resistance of the conductive layer, and as a result, only the film that is in close contact with the material to be heated generates heat, and the thermal efficiency is excellent.

That is, when a fluctuating magnetic field traverses the conductor, an eddy current is generated in the conductive layer of the film so as to generate a magnetic field that prevents the change of the magnetic field. This eddy current causes the skin resistance of the conductive layer of the film to generate heat in the conductive layer of the film with an electric power proportional to the skin resistance. Since heat is generated directly near the surface layer of the film, there is an advantage that heating can be performed rapidly regardless of the thermal conductivity and heat capacity of the film base layer. In addition, rapid heating that does not depend on the film thickness can be realized.

Thus, it is possible to achieve a high-rigidity thick film of the film base layer without sacrificing energy saving and quick start properties, and to cope with high speed.

[0012]

In such an electromagnetic induction type apparatus, the magnetic field generating means is generally constituted by an exciting coil wound around an exciting iron core (core material), and the magnetic field generating means intersects the direction in which the material to be heated is conveyed. Is a series of horizontally long members having a length dimension corresponding to the maximum sheet passing width of the material to be heated,
When the exciting coil is energized, the conductive member width region corresponding to the maximum sheet passing width of the heated material generates heat.

Therefore, when a material to be heated having a width smaller than the maximum paper-passing width is passed, an excessive temperature rise occurs in the non-sheet-passing area (non-sheet-passing portion excessive temperature rise), and the magnetic permeability of the exciting core is increased. The amount of heat generated becomes unstable even in the paper passing area. Further, there is a problem that the deterioration of the exciting coil is promoted if the temperature rise of the exciting coil portion is large.

In view of the above, the present invention relates to an electromagnetic induction type heating device, which prevents the above-mentioned phenomenon of excessive temperature rise in the non-sheet passing portion and makes the heat generation distribution in the sheet passing portion area uniform, thereby performing stable heat treatment of the material to be heated. The goal is to be able to do.

[0015]

The present invention is a heating device and an image forming apparatus characterized by the following configurations.

(1) Electromagnetic induction for heating a material to be heated which is conveyed in direct or indirect contact with the conductive member due to heat generated by an eddy current generated in the conductive member by applying a magnetic field to the fixed or moving conductive member. A heating device of a heating type, wherein the magnetic field generating means is divided and configured in a direction intersecting a conveyance direction of a material to be heated.

(2) The heating device according to (1), characterized in that an auxiliary magnetic field generating means is arranged between the divided magnetic field generating means of the magnetic field generating means constituted by division.

(3) The heating device according to (1), characterized in that the demagnetizing means is provided in at least a part of the divided magnetic field generating means of the magnetic field generating means constituted by division.

(4) The magnetic field generating means, the auxiliary magnetic field generating means, and the demagnetizing means are exciting coils or demagnetizing coils through which an alternating current flows, and are described in any one of (1) to (3). Heating device.

(5) The heating device according to any one of (1) to (4), further comprising a pressing member for directly or indirectly adhering the member to be heated to the conductive member.

(6) The heating device according to (5), wherein the pressure member is a pressure rotating body which is rotationally driven or driven to rotate.

(7) The heating device according to any one of (1) to (6), wherein the conductive member is a rotary endless member or a traveling / moving end member.

(8) The heating device according to any one of (1) to (7), wherein the conductive member is a laminated member including a conductive layer or a member itself conductive.

(9) The heating target material is a recording material supporting an unfixed image, and the image heating fixing device heat-fixes the unfixed image on the recording material (1) to 1). The heating device according to any one of (8).

(10) An image forming apparatus comprising the heating device according to any one of (1) to (9) as an image heating and fixing device for heating and fixing an unfixed image on a recording material. .

[0026]

The magnetic field generating means having a length dimension that extends over the maximum paper-passing width of the heated material is divided into several parts in the paper-passing direction of the heated material, that is, in the direction intersecting (orthogonal to) the conveying direction of the heated material. , The individual magnetic field generation means are selectively controlled to generate a magnetic field according to the size of the width of the heated material used in the apparatus, and the heated material used in the apparatus has the maximum sheet passing width. In the case of a large size width corresponding to the above, by controlling all the divided magnetic field generating means to the magnetic field generating state, the width area of the conductive member corresponding to the maximum sheet passing width generates heat and the heated material of the large size width. If the material to be heated used in the device has a size smaller than the maximum sheet passing width, the divided magnetic field corresponding to the sheet passing part area of the material to be heated of this small size width can be applied. The generation means is controlled to the magnetic field generation state, and the non-sheet passing area By controlling the corresponding divided magnetic field generating means so as not to generate a magnetic field, only the conductive member width area corresponding to the sheet passing area of the heated material having the small size width generates heat, and the small size width It is possible to perform the heating process on the material to be heated without causing the excessive temperature rise phenomenon of the non-sheet passing portion.

Further, the heat generation distribution of the conductive member portion corresponding to the paper passing portion area is made uniform, and stable heat treatment of the material to be heated becomes possible.

By disposing the auxiliary magnetic field generating means between the divided magnetic field generating means of the magnetic field generating means constituted by division, it is possible to compensate for the decrease of the heat generation distribution due to the non-uniform magnetic field between the divided magnetic field generating means.

[0029]

【Example】

<Embodiment 1> (FIGS. 1 to 3) FIG. 1 is a schematic view showing the configuration of an example of an electromagnetic induction heating device according to the present invention.

(1) Overall schematic configuration of the apparatus 1 is a substantially U-shaped film inner surface guide stay having an upward cross section, and this stay 1 is composed of a liquid crystal polymer, phenol resin or the like, and has a magnetic field generating means inside. As described above, the exciting coil 3 formed by winding the iron core (core material) 2 is housed.

This stay 1 and iron core 2 and exciting coil 3
The assembly (electromagnetic induction heating structure) is a laterally long member having a longitudinal direction in a direction intersecting (orthogonal) with a transporting (moving) direction of a film 4 and a recording material (heating material) P described later. The coil 3 is divided and configured in the longitudinal direction as described later (FIGS. 2 and 3).

An endless (cylindrical, seamless) heat-resistant film 4 as a conductive member (heating member) is loosely fitted on the outside of the assemblies 1, 2, and 3.

Reference numeral 5 is a pressure roller, which is formed by coating the core metal with silicone rubber, fluororubber or the like. The pressure roller 5 is in pressure contact with the lower surface of the stay 1 by sandwiching the film 4 against the lower surface of the stay 1 with a predetermined pressing force by bearing means and urging means (not shown).
A pressure contact nip portion (fixing nip portion) N is formed by sandwiching.

The pressure roller 5 is rotationally driven by the drive means M in the counterclockwise direction indicated by the arrow. A rotational force acts on the film 4 by the frictional force between the pressure roller 5 and the outer surface of the film due to the rotational driving of the pressure roller 5, and the film 4 slides in close contact with the lower surface of the stay 1 to rotate around the stay 1. . In this case, grease should be applied between the lower surface of stay 1 and the inner surface of film 4.
It is preferable to apply a lubricant such as oil.

The film 4 as a conductive member has a thickness of 10 μm.
m ~ 100μm polyimide / polyamideimide / PE
A heat-resistant resin such as EK / PES / PPS / PEA / PTFE / FEP is used as the base layer 4a of the endless film, and the conductive layer 4b is provided on the outer periphery of the base layer 4a (on the pressure-contact surface side of the material to be heated).
For example, a layer of iron or cobalt, or a metal layer of nickel, copper, chromium, etc., by plating treatment, for example, 1 μm to 100 μm
It is formed with the thickness of. Further, as an outermost layer (surface layer) on the free surface of the conductive layer 4b, for example, PFA / PTFE / FE is used.
This is a three-layer structure in which a release layer 4c is formed by mixing or independently coating a heat-resistant resin having a good toner release property such as P.silicone resin. In this example, the film base layer 4a and the conductive layer 4b are separate layers, but the film base layer 4a itself may be the conductive layer.

By applying an alternating current to the exciting coil 3 from an exciting circuit (not shown), the conductive layer 4b of the film 4 generates heat by electromagnetic induction heating.

Reference numeral 6 is a thermistor which is a temperature detecting element for detecting the surface temperature of the pressure roller 5, and controls the current value applied to the exciting coil 3 based on the temperature detected by the thermistor 6. When the pressure roller 5 is cold and the temperature detected by the thermistor 6 is low, the duty ratio for energization is increased, and when the detected temperature is high, the duty ratio for energization is decreased. The thermistor 6 can be provided on the film non-sliding surface of the stay 1 or on the iron core 2.

Reference numeral 7 is a safety element such as a temperature fuse or a thermoswitch that cuts off energization to the exciting coil 3 when the temperature rises excessively.

Thus, when the film 4 is rotated by the rotation of the pressure roller 5 and a current is applied from the exciting circuit to the exciting coil 3 to heat the conductive layer 4b of the film 4, the pressure contact nip portion N is formed. The recording material P as a material to be heated is introduced into the surface of the recording material P, and the recording material P comes into close contact with the surface of the film 4 and passes through the pressure contact nip portion N together with the film. The unfixed toner image T applied to the toner is heat-fixed T ′. The recording material P passing through the pressure nip portion N is separated from the surface of the film 4 and conveyed.

(2) Heating principle An alternating current is applied to the exciting coil 3 from the exciting circuit, whereby the magnetic flux indicated by the arrow H is repeatedly generated and extinguished around the coil 3. This magnetic flux H is generated by the conductive layer 4b of the film 4.
The iron core 2 is configured so as to traverse.

When a fluctuating magnetic field traverses in a conductor, eddy currents are generated in the conductor so as to create a magnetic field that impedes changes in the magnetic field. This eddy current is indicated by arrow A.

Due to the skin effect, this eddy current mostly flows concentratedly on the surface of the conductive layer 4b on the coil 3 side, and heat is generated by electric power proportional to the skin resistance R _S of the film conductive layer 4b.

R _S is the skin depth obtained from the angular frequency ω, the magnetic permeability μ, and the specific resistance ρ.

[0044]

[Outside 1] Can be expressed as

Therefore, the power can be increased and the amount of heat generation can be increased by increasing R _S or increasing I _f .

To increase R _S , the frequency ω may be increased, or a material having a high magnetic permeability μ and a material having a high specific resistance ρ may be used.

From now on, the non-magnetic metal is added to the conductive layer 4b.
It is presumed that it is difficult to heat when used for the conductive layer 4
When the thickness t of b is smaller than the skin depth δ, R _S ≈ρ / t, and thus heating is possible.

The frequency of the alternating current applied to the exciting coil 3 is preferably 10 to 500 kHz.

When the frequency is 10 kHz or more, the absorption efficiency into the conductive layer 4b is improved, and up to 500 kHz, an exciting circuit can be assembled by using an inexpensive element.

Further, if the frequency is 20 kHz or more, the sound exceeds the audible range and no noise is generated when energized, and if it is 200 kHz or less, the loss generated in the exciting circuit is small and the radiation noise to the surroundings is small.

When an alternating current of 10 to 500 kHz is applied to the conductive layer 4b, the skin depth is several μm to several hundreds μm.
It is a degree.

When the thickness of the conductive layer 4b is actually smaller than 1 μm, most of the electromagnetic energy cannot be absorbed by the conductive layer 4b, resulting in poor energy efficiency.

There is also a problem that the leaked magnetic field heats other metal parts.

On the other hand, in the conductive layer 4b having a thickness of more than 100 μ, the rigidity of the film 4 becomes too high, and heat is transferred by the heat conduction in the conductive layer 4b, so that the releasing layer 4c becomes difficult to warm up.

Therefore, the thickness of the conductive layer 4b is 1 to 100 μm.
Is preferred.

To increase the heat generation of the conductive layer 4b, I _f
Is increased, and for that purpose, the magnetic flux generated by the coil 3 may be strengthened or the change of the magnetic flux may be increased. As this method, the number of windings of the coil 3 may be increased, or the iron core 2 of the coil 3 may be made of ferrite or permalloy having a high magnetic permeability and a low residual magnetic flux density.

If the resistance value of the conductive layer 4b of the film 4 is too small, the heat generation efficiency when an eddy current is generated deteriorates. Therefore, the specific volume low efficiency of the conductive layer 4b is 1.
It is preferably 5 × 10 ⁻⁸ Ωm or more.

In this embodiment, the conductive layer 4b of the film 4 is formed by plating, but it may be formed by vacuum evaporation, sputtering or the like. As a result, aluminum or metal oxide alloy that cannot be plated can be used for the conductive layer 4b. However, it is preferable to perform the plating treatment in order to obtain a layer thickness of 1 to 100 μm because the plating treatment can easily obtain the film thickness.

For example, when a ferromagnetic material such as iron, cobalt, nickel or the like having a high transmittance is attached, the electromagnetic energy generated by the exciting coil 3 can be easily absorbed, the heating can be efficiently performed, and the magnetism leaked out of the machine is small. It also reduces the impact on peripheral devices. Moreover, it is better to select one of these with high and low efficiency.

The conductive layer 4b of the film 4 is made of not only metal but also conductive and high magnetic permeability particles and whiskers dispersed in an adhesive for bonding the surface release layer to the low thermal conductive base material. It may be used as a conductive layer.

For example, manganese, titanium, chromium, iron,
Particles of copper, cobalt, nickel or the like, particles of these alloys such as ferrite or oxide, or whiskers can be mixed with conductive particles such as carbon and dispersed in an adhesive to form a conductive layer.

As described above, since heat is directly generated near the surface layer of the film 4, there is an advantage that heating can be performed rapidly regardless of the thermal conductivity and heat capacity of the film base material (base layer) 4a.

Further, since it does not depend on the thickness of the film 4, in order to improve the rigidity of the film 4 for speeding up, even if the base material 4a of the film 4 is thickened, it can be quickly heated to the fixing temperature.

Further, since the film base material 4a is a resin having a low thermal conductivity, it has a good heat insulating property, and it can be insulated from a coil having a large heat capacity such as a coil inside the film, so that heat loss is small even if continuous printing is performed. , Energy efficient. Moreover, heat is not transmitted to the coil 3 in the film, and the performance of the coil does not deteriorate.

Since the thermal efficiency is improved, the temperature rise in the apparatus can be suppressed and the influence on the image forming portion of the image forming apparatus such as an electrophotographic apparatus using the heating apparatus as an image heating and fixing apparatus can be reduced.

(3) Divided configuration of the magnetic field generating means 2 and 3 (FIGS. 2 and 3) In this embodiment, the exciting iron core 2 and the coil 3 as the magnetic field generating means are arranged in the longitudinal direction thereof as shown in FIGS. That is, in the direction intersecting (orthogonal) with the transport direction of the film 4 and the recording material (heating material) P, the first to third exciting coil units 2a, 3a, 2b, 3b, 2c, 3c are divided. Configured. OO is a one-sided sheet passing reference line of the recording material P. P1, P2, and P3 are the paper passing width areas based on the one-sided paper passing reference line OO, which correspond to recording materials having three types of large, medium, and small size widths, respectively, and P1>P2> P3. Have a relationship.

The total length of the first to third three divided excitation coil units 2a, 3a, 2b, 3b, 2c, 3c substantially corresponds to the large size sheet passing width area (maximum sheet passing width) P1, and the first and second 2 divided excitation coil units 2a, 3a, 2b
-The total length of 3b is almost equivalent to the medium size paper width area P2,
The length of the first divided excitation coil units 2a and 3a substantially corresponds to the small-size sheet passing width region P3.

First to third divided excitation coil units 2a
.3a, 2b, 3b, 2c, 3c coils 3a, 3b
Energization of 3c is selectively performed independently according to the width size of the recording material to be passed.

That is, when a large-sized recording material is passed, the first to third three divided excitation coil units 2 corresponding to the sheet passing width region P1 according to the temperature detected by the thermistor 6.
a. 3a, 2b, 3b, 2c, 3c coils 3a. 3
The conductive layer 4b of the film 4 is supplied by energizing b3c.
Generates heat in the large-size sheet passing width region P1, and the large-sized recording material is heat-treated.

When a medium-sized recording material is passed, the first and second two exciting coil units 2a and 3a corresponding to the sheet passing width region P2 according to the temperature detected by the thermistor 6,
By energizing the coils 3a and 3b of 2b and 3b,
The conductive layer 4b of the film 4 generates heat in the medium-size sheet passing width region P2, and the medium-size recording material is heat-treated.

At this time, with respect to the coils 3c of the third divided excitation coil units 2c and 3c corresponding to the non-sheet passing portion area, current value control (energization interruption or cut-off of current supply) is performed so that the film conductive layer portion in the non-sheet passing portion area does not generate heat. The energization amount reduction control) is performed.

When a small-sized recording material is passed, the coils 3a of the first divided excitation coil units 2a and 3a corresponding to the passing width region P3 are energized according to the temperature detected by the thermistor 6, The conductive layer 4b of the film 4 generates heat in the small-size sheet passing width region P3, and the small-sized recording material is heat-treated.

At this time, the second and third divided exciting coil units 2b, 3b, 2c.
Regarding the coils 3b and 3c of 3c, the current value is controlled so that the film conductive layer portion in the non-sheet passing portion area does not generate heat.

As a result, it is possible to prevent the excessive temperature rise phenomenon of the non-sheet-passing portion in the case of passing a medium-sized or small-sized recording material.

When the exciting core / coil as the magnetic field generating means is not composed of exciting coil units divided according to the sheet size as in the present invention but is formed of an integral exciting coil in the longitudinal direction, the Since the temperature of the paper passing portion is 100 to 200 degrees higher than the temperature of the paper passing portion because there is no heat exhausting effect of the recording material P as the heated material, heat is not transferred due to heat conduction in the integrated excitation core material. Excessive temperature rise not only to the paper passing area but also to the excitation core material in the paper passing area,
Therefore, the magnetic flux generated from the core material in which the spontaneous magnetization in the core material is reduced is reduced. Therefore, the conductive layer 4b of the film 4
The eddy current that is induced in the coil decreases, and the amount of heat generated decreases. As a result, fixing failure occurs on the non-passing reference side of the sheet passing area. Furthermore, since the decrease in the magnetic field generated by the exciting core material 2 is compensated for by the increase in energization, the energy efficiency is extremely reduced.

On the other hand, the independent energization control according to the sheet passing size of the divided excitation coil unit according to the present invention does not affect the sheet passing area due to the excessive temperature rise of the non-sheet passing section and stabilizes with high energy conversion efficiency. It is possible to achieve uniform heat generation.

<Embodiment 2> (FIG. 4) FIG. 4 shows heat generation at the boundary between the first to third split excitation coil units 2a, 3a, 2b, 3b, 2c, 3c shown in FIG. 2 and FIG. In order to further homogenize the distribution, the first and second auxiliary exciting coil units 2d, 3d, 2e, 3e are arranged in a zigzag pattern between the exciting coil units.

First and second auxiliary excitation coil units 2d
3d, 2e, and 3e are the exciting coils 3a of the first and second divided exciting coil units 2a, 3a, 2b, and 3b, respectively.
When the 3b is energized, the energization is performed to compensate for the decrease in the heat generation distribution due to the non-uniform magnetic field between the exciting coils 3a and 3b. The second and third split exciting coil units 2b, 3b, 2c 3c Excitation coil When energizing the excitation coils 3b and 3c, the excitation coil 3e of the second auxiliary excitation coil units 2e and 3e is energized to compensate for a similar non-uniform magnetic field between the excitation coils.

<Embodiment 3> (FIGS. 5 and 6) In this embodiment, a demagnetizing coil unit is provided side by side to demagnetize the magnetic field generated by the exciting coil unit corresponding to the non-sheet passing portion area, thereby deactivating the non-sheet passing portion. This is to prevent excessive temperature rise.

That is, the one shown in FIG. 5 is constructed by dividing an exciting iron core / coil as magnetic field generating means into two first and second exciting coil units 2a, 3a, 2b and 3b,
The demagnetization coil units 2f and 3f are arranged on the second split excitation coil units 2b and 3b.

When a large-sized recording material is passed, the large-sized sheet passing width region P1 is detected according to the temperature detected by the thermistor 6.
When the coils 3a and 3b of the first and second divided excitation coil units 2a, 3a, 2b and 3b corresponding to the above are energized, the conductive layer b of the film 4 generates heat in the large size sheet passing width region P1. Then, the large-sized recording material is heat-treated.

When a recording material of a size smaller than that is passed, the coils 3a of the first divided excitation coil units 2a and 3a corresponding to the sheet passing width region P2 are energized according to the temperature detected by the thermistor 6. By that, film 4
The conductive layer 4b generates heat in the small-size sheet passing width region P2, and the small-sized recording material is heat-treated.

At this time, the exciting coils of the second divided exciting coil units 2b and 3b corresponding to the non-sheet passing area are also energized, but the coils 3f of the corresponding demagnetizing coil units 2f and 3f are also energized. Is to demagnetize the magnetic field generated by the second divided excitation coil units 2b and 3b located below the excitation coil 3 by, for example, the excitation coil 3.
demagnetization coil unit 2f in the direction opposite to the coil winding direction of b
This can be achieved by forming the 3f coil 3f or by shifting the phase of the alternating current waveform applied to the exciting coil. Even in such a configuration, the conductive layer 4b of the film 4
Since the internal magnetic field is reduced, it is possible to partially suppress the heat generation.

As shown in FIG. 6, the demagnetizing coil 3 is provided in the non-sheet passing area of one exciting coil unit 2/3 having the maximum sheet passing size.
The same effect can be achieved by disposing g.

<Embodiment 4> (FIG. 7) In the present embodiment, the magnetic field generating means and the conductive member are vertically opposed to each other and face each other or are in contact with each other. It is an electromagnetic induction heating structure (heater) made of a magnetic metal material 9 as an induction magnetic material. By exposing the electromagnetic induction heating structures 8 and 9 with the magnetic metal material 9 facing downward, a film inner surface guide stay 1 having a substantially semicircular cross section having rigidity and heat resistance formed of a thermosetting resin or the like is provided. It is fitted and held along the length of the guide in a substantially central portion of the lower surface.

Reference numeral 10 denotes an endless heat-resistant film, which is loosely fitted onto the film inner surface guide stay 1 including the electromagnetic induction heating structures 8 and 9, and the film 10 is electromagnetically induced by the pressure roller 5. Heating structure 8 ・ 9
It is pressed against the lower surface of the magnetic metal material 9. Film 10
Does not have a conductive layer.

The pressure roller 5 is rotationally driven in the counterclockwise direction indicated by the arrow by the driving means M, and the film 10 is rubbed by the rotational force of the pressure roller 5 between the roller and the outer surface of the film.
The rotational force acts on the film 10, and the film 10 is brought into close contact with the lower surface of the magnetic metal material 9 to slide and rotate.

The high frequency magnetic field generated from the magnetic field coil of the field coil plate 8 is magnetically coupled to the magnetic metal material 9, and the magnetic metal material 9 is heated by the eddy current loss caused by magnetism. The heat resistant film 10 that closely moves to the magnetic metal material 9 is heated.

Thus, an image as a material to be heated is fixed between the pressure roller 5 and the film 10 in the pressure contact nip portion N formed by the magnetic metal material 9 and the pressure roller 5 with the film 10 interposed therebetween. The recording material P to be recorded is introduced from an image forming unit (not shown) and is nipped and conveyed together with the film 10 in the pressure contact nip portion N, so that the heat of the magnetic metal material 9 is applied to the recording material P via the film 10. Then, the unfixed toner image T on the recording material P is heated and fixed on the surface of the recording material P. The recording material P passing through the pressure nip portion N is separated from the surface of the film 10 and conveyed.

Also in the apparatus of this example, the electromagnetic induction heating structures 8 and 9 are divided in the longitudinal direction thereof, so that the excessive temperature rise phenomenon of the non-sheet passing portion can be prevented as in the first embodiment. It can be lost.

<Embodiment 5> (FIG. 8) FIGS. 8A, 8B, and 8C show another example of the configuration of the electromagnetic induction heating type heating device.

(A) is an electromagnetic induction heating structure 1.2.
A film 4 serving as an endless belt-shaped conductive member is suspended and stretched between the three members of the lower surface of the stay 1 of 3, the driving roller 11, and the driven roller (tension roller) 12, and the film is driven by the driving roller 11. 4 is rotationally driven. Reference numeral 13 denotes a pressure roller that is pressed against the lower surface of the stay with the film 4 interposed therebetween, and is driven to rotate as the film 4 rotates.

In (b), the electromagnetic induction heating structure 1
A film 4 as an endless belt-shaped conductive member is suspended and stretched between the lower surface of the 2.3 stay 1 and two members of the drive roller 11 and is rotationally driven by the drive roller 11.

In the case of (c), as the film 4 as the conductive member, a long end film wound in a roll is used instead of the endless belt-like film, and this is wound from the feeding shaft 14 side to the electromagnetic induction heating structure. The body 1, 2, 3 is configured to run at a predetermined speed to the winding shaft 15 side via the stay lower surface.

<Embodiment 6> (FIG. 9) This embodiment is a schematic configuration diagram of an example of an image forming apparatus in which the heating device of the electromagnetic induction heating system of Embodiment 1 is used as the image heating and fixing device 31. The image forming apparatus of this example is a laser beam printer using an electrophotographic process.

Reference numeral 21 denotes a rotary drum type electrophotographic photosensitive member (hereinafter referred to as a drum) as an image bearing member, which is rotationally driven in the clockwise direction indicated by an arrow at a predetermined peripheral speed (process speed).

The drum 21 is uniformly charged with a predetermined polarity and potential by the primary charger 22 during its rotation process, and the charged surface of the drum 21 is laser-scanned by the laser scanner 23 in accordance with the desired image information. By performing the beam scanning exposure L, an electrostatic latent image corresponding to the target image information is formed on the peripheral surface thereof.

The formed electrostatic latent image is subjected to reversal development processing with the toner T by the developing device 24 to be visualized, and the toner image forming surface is transferred to the pressure contact nip portion between the drum 21 and the transfer roller 25. It will shift.

Reference numeral 27 denotes a cassette in which transfer material sheets P as recording materials are stacked and accommodated. The sheets P in the cassette 27 are fed out one by one by the rotation of a feeding roller 28, and then by a registration roller 29. When the leading edge of the toner image forming portion on the drum 21 reaches the transfer portion, the leading edge of the transfer material sheet P also reaches the transfer portion and is fed in a timed manner so that they coincide with each other.

Then, the toner images on the drum 21 side are sequentially transferred to the surface of the fed sheet by the transfer roller 25.

The sheet to which the toner image has been transferred at the transfer portion is sequentially separated from the surface of the drum 21 by separating means (not shown), and is guided to the fixing device 31 by the conveyance guide device 30 and carried by the unfixed toner. The image T is heated and fixed, and is discharged as an image formed product (copy) onto a discharge tray 34 outside the machine through a guide 32 and a discharge roller 33.

The surface of the drum 21 after the image transfer is subjected to removal of adhered contaminants such as transfer residual toner by the cleaning device 26, and is repeatedly used for image formation.

The PC is a process cartridge which is attached / detached to / from the cartridge attaching / detaching portion in the printer main body. In the case of this example, the four processes of the drum 21, the charging device 22, the developing device 24, and the cleaning device 26 as an image carrier. The device is included and can be attached / detached to / from the printer body in a lump.

[0104]

As described above, according to the present invention, in the heating device of the electromagnetic induction system, the phenomenon of excessive temperature rise of the non-sheet passing portion is prevented, and the heat generation distribution in the sheet passing portion area is made uniform to be heated. A stable heat treatment of the material can be performed.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a schematic configuration of a heating device according to a first embodiment.

FIG. 2 is a perspective view of first to third divided excitation coil units.

FIG. 3 is a plan view thereof

FIG. 4 is a plan view of an example in which an auxiliary excitation coil unit is added.

FIG. 5 is a perspective view of a divided excitation coil unit provided with a demagnetization coil unit.

FIG. 6 is a perspective view of an exciting coil unit provided with a demagnetizing coil.

FIG. 7 is a schematic diagram of another configuration example of the heating device.

8 (a), (b), and (c) are schematic diagrams of other configuration examples of the heating device, respectively.

FIG. 9 is a schematic configuration diagram of an example of an image forming apparatus.

[Explanation of symbols]

1 film inner surface guide stay 2.3 iron core (core material) as magnetic field generating means and exciting coil 4 film as conductive member 4a film base layer 4b conductive layer 4c release layer 5 pressure roller N pressure contact nip P as heated material Recording material 6 Temperature detection element (thermistor) 7 Safety element (thermal fuse, thermo switch, etc.) 8 Field coil plate 9 Induction magnetic material (magnetic metal material) 10 Heat resistant film

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoshinori Sugiura 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Kenichi Ogawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Within the corporation

Claims (10)

[Claims] 1. Electromagnetic induction heating for heating a material to be heated which is conveyed in direct or indirect contact with the conductive member due to heat generated by an eddy current generated in the conductive member by applying a magnetic field to a fixed or moving conductive member. A heating device of a system, wherein the magnetic field generating means is divided and configured in a direction intersecting a conveyance direction of a material to be heated. 2. The heating apparatus according to claim 1, wherein an auxiliary magnetic field generating means is arranged between the divided magnetic field generating means of the magnetic field generating means which is divided. 3. The heating device according to claim 1, wherein demagnetizing means is provided in at least a part of the divided magnetic field generating means of the magnetic field generating means formed by dividing. 4. The heating according to claim 1, wherein the magnetic field generating means, the auxiliary magnetic field generating means, and the demagnetizing means are exciting coils or demagnetizing coils through which an alternating current flows. apparatus. 5. The heating device according to claim 1, further comprising a pressing member for directly or indirectly adhering the member to be heated to the conductive member. 6. The heating device according to claim 5, wherein the pressure member is a pressure rotating body that is rotationally driven or driven to rotate. 7. The heating device according to claim 1, wherein the conductive member is a rotary endless member or a traveling / moving end member. 8. The conductive member is a laminated member including a conductive layer or a conductive member itself.
The heating device according to any one of 1 to 7. 9. The image heating fixing device according to claim 1, wherein the material to be heated is a recording material carrying an unfixed image, and the image heating fixing device heat-fixes the unfixed image on the recording material. The heating device according to any one of 8. 10. An image forming apparatus comprising the heating device according to claim 1 as an image heating fixing device for heating and fixing an unfixed image on a recording material.