JPH086413A - Heating device and image forming device - Google Patents

Abstract

PURPOSE:To enhance the accuracy of a system detecting the temperature of the required part of a device and controlling the device by making a temperature detection element arranged in the device of a metal. CONSTITUTION:An E type core material 1 being as a magnetic field generation means and an exciting coil 2 wound round the core material 1 are a long sideways member obtained by defining a direction crossed(orthogonally crossed) to the carrying(moving) direction of a film 5 and a material to be recorded(material to be heated) P as a longitudinal direction. Then, the temperature of the film 5 being the heating member is measured by the temperature detection element 7. Based on the measured temperature, the excitation circuit 10 of an exciting coil 2 is controlled by a regulator 11 and the value of a current impressed on the coil 2 is controlled. Then, the temperature(fixing temperature) of the film 5 is precisely controlled. In such a case, the element 7 detecting the surface temperature of the film 5 is a thermoelectric couple being as the metallic temperature detection element. Such a thermoelectric couple is used because the calorific capacity thereof is small, the heat conductivity thereof is excellent and it can be closely brought into contact with the film 5 by utilizing the spring property of the metal itself.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, a recording material heating device for heating and fixing an image, that is, an image of a copying machine, a laser beam printer, a facsimile, a microfilm reader printer, an image display (display) device, a recording machine, etc. In the forming apparatus, a recording material (electrofax sheet, electrostatic recording sheet, transfer material sheet, transfer material sheet, or the like) is formed by using a toner made of a heat-meltable resin or the like by an appropriate image forming process means such as electrophotography, electrostatic recording, and magnetic recording. Printing paper etc.)
Image (unfixed toner image) corresponding to the target image information formed on the surface of the paper by direct method or indirect (transfer) method
As an image heating and fixing device (image heating device) for performing heat fixing processing as a permanently fixed image on the surface of a recording material carrying the image, a contact heating type device such as a heat roller type or a film heating type is widely used. ing.

In such an apparatus, an electric current is passed through a halogen lamp and a heating resistor to generate heat, and a toner image is heated through a roller or a film as a heating member.

On the other hand, there is also an electromagnetic induction heating type heating device. Japanese Patent Publication No. 5-9027 proposes that eddy current (eddy current) is generated in a fixing roller as a heating member by magnetic flux to generate heat by Joule heat.

By utilizing the generation of the eddy current as described above, the heat generation position can be brought closer to the toner, and the warm-up time can be shortened as compared with the heat roller system using the halogen lamp.

Further, the present inventors have conducted research on a heating device of an electromagnetic induction heating system / film heating system in which the film itself as a heating member is heated so that the film does not become a thermal resistance and the thermal efficiency is improved. Came.

This is to change the magnetic field generated in the exciting circuit by combining magnetic field generating means, for example, a core material which is a magnetic body and an exciting coil. That is, by applying a high frequency to the coil, a magnetic field is repeatedly generated and extinguished in the film as a conductive member (inductive magnetic material, magnetic field absorbing conductive material) that moves in the generated magnetic field, and an eddy current is generated in the conductive layer in the film. It is what is generated. This eddy current is converted into heat (Joule heat) by the electric resistance of the conductive layer, and as a result, only the film serving as the heating member that comes into 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. As described above, since heat is generated directly near the surface layer of the film as the heating member, 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 increase the thickness and rigidity of the film base layer without sacrificing energy saving and quick start properties, and to cope with durability and speeding up.

[0010]

SUMMARY OF THE INVENTION The present invention relates to an electromagnetic induction heating type heating device, among the various heating devices described above, in which the accuracy of a system for detecting the temperature of a required part of the device and controlling the device is improved. The purpose is to provide improved reliability.

[0011]

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

(1) An electromagnetic induction heating type heating device for heating a material to be heated by heat generation of the conductive member by an eddy current generated in the conductive member by applying a magnetic field to the conductive member by the magnetic field generating means. A heating device characterized in that the temperature detecting element arranged at is a metallic temperature detecting element.

(2) An electromagnetic induction heating type heating device for heating a material to be heated by heat generation of the conductive member caused by an eddy current generated in the conductive member by applying a magnetic field to the conductive member by the magnetic field generating means. A heating device characterized in that the temperature detecting element arranged in the above is a metallic temperature detecting element, and is arranged so that magnetic lines of force generated by the exciting coil of the magnetic field generating means enter.

(3) An electromagnetic induction heating type heating device for heating a material to be heated by heat generation of the conductive member by an eddy current generated in the conductive member by applying a magnetic field to the conductive member by the magnetic field generating means. A heating device, characterized in that a metal piece is brought into contact with the temperature detecting element arranged at.

(4) An electromagnetic induction heating type heating device for heating a material to be heated by heat generation of the conductive member by an eddy current generated in the conductive member by applying a magnetic field to the conductive member by the magnetic field generating means. A heating device, characterized in that a metal piece is brought into contact with the temperature detecting element arranged in (1), and the magnetic field line generated by the exciting coil of the magnetic field generating means is inserted.

(5) The heating device according to any one of (1) to (4), characterized in that the conductive member is a fixed member, or a rotating member or a member for traveling and moving.

(6) The heating device according to any one of (1) to (5), wherein the conductive member is a laminated member including a conductive layer or a member itself conductive.

(7) The heating device according to any one of (1) to (6), further comprising a pressing member for directly or indirectly adhering the member to be heated to the conductive member.

(8) The heating device according to (7), wherein the pressure member is a pressure rotating body that is rotationally driven or driven to rotate.

(9) The material to be heated is a recording material carrying an image to be heat-treated, and is an image heating device for heating the image on the recording material (1) to (). 8)
The heating device according to any one of 1.

(10) An image forming apparatus comprising the heating device according to any one of (1) to (9) as an image heating device.

[0022]

[Action]

a. By making the temperature sensing element metallic, for example, by utilizing the resistance change of a thermocouple or platinum, the temperature sensing element has a small heat capacity, good thermal conductivity, and the spring property of the metal itself. By utilizing this, it is possible to press-contact the object such as the heating member of the electromagnetic induction heating device with a light load and satisfactorily, and it is possible to improve the accuracy and the responsiveness.

B. Further, by arranging the metallic temperature detecting element so that the magnetic field lines created by the exciting coil of the magnetic field generating means of the electromagnetic induction heating device enter, the metallic temperature detecting element itself also generates heat by eddy current. Therefore, it is possible to arrange the temperature detecting element in a non-contact state with a subject such as a heating member of an electromagnetic induction heating device and detect how much energy is applied to the subject. That is, non-contact detection of the subject temperature is possible.

As a result, it is possible to solve the problems that the temperature sensing element is brought into contact with the subject and that the subject is scratched and the driving torque of the subject is increased. In addition, the temperature detecting element itself does not require a protective film or the like.

In particular, since the amount of heat actually supplied to the subject can be directly detected by this non-contact detection, temperature control can be performed without being influenced by circuit variations and temperature sensor contact state variations.

C. Even if the temperature detecting element is not metallic, for example, even if it is a semi-conductive one such as a thermistor, a metal temperature detecting element as described in the above item a is formed by abutting the addition of a metal piece. The same effect as can be obtained.

D. Further, by disposing the temperature detecting element to which the metal piece is abutted and added so that the magnetic field lines created by the exciting coil of the magnetic field generating means of the electromagnetic induction heating device may enter, the temperature detecting element in the case of the metallic temperature detecting element of the above item b may be obtained. The same effect can be obtained.

[0028]

【Example】

<Embodiment 1> (FIGS. 1 to 3) (1) Overall schematic configuration of apparatus FIG. 1 is a schematic cross-sectional view showing the configuration of an example of an electromagnetic induction heating type heating apparatus according to the present invention. The heating device of this embodiment is an electromagnetic induction heating type / film heating type image heating / fixing device (image heating device) using a rotating endless film (fixing film) having a conductive layer as a conductive member (heating member). . FIG. 2 is a perspective view of a core material (magnetic field generation means) and an exciting coil.

Reference numerals 1 and 2 are an E-shaped core material as a magnetic field generating means and an exciting coil wound around the E-shaped core material. This core material 1
The exciting coil 2 is a laterally long member having a length in a direction intersecting (orthogonal) with a conveying (moving) direction of a film 5 and a recording material (heating material) P described later.

3, 3 is a core material 1 around which an exciting coil 2 is wound.
Is a stay for supporting the film 5 and for keeping the film 5 running, and is made of a liquid crystal polymer, a phenolic resin, or the like, and a rubbing plate is attached to a portion in contact with the film.

The stays 3 and 3 are laterally long members arranged so that the three legs of the E-shaped core 1 around which the exciting coil 2 is wound face downward and both longitudinal sides thereof are sandwiched.

Reference numeral 4 is an E-shaped core material 1 around which an exciting coil 2 is wound.
It is a film sliding plate (sliding plate) provided on the downward surface, and is glass or the like having a small frictional resistance with the film 5. Further, it is preferable to apply a lubricant such as grease or oil to the surface thereof. Alternatively, the film sliding portion may be configured as a smooth surface with the core material 1.

The above core material 1, exciting coil 2, stay 3,
An endless (cylindrical, seamless) heat-resistant film 5 as a conductive member is loosely fitted outside the assembly (electromagnetic induction heating structure) including the film sliding plate 4 and the like.

Reference numeral 6 is a pressure roller, which is formed by coating the core metal with silicone rubber, fluororubber or the like. The pressure roller 6 is pressed against the lower surface of the film sliding plate 4 of each of the above-mentioned assemblies 1 to 4 by sandwiching the film 5 with a predetermined pressing force by bearing means and biasing means (not shown). The film 5 is sandwiched between the lower surface of the moving plate 4 and the lower surface of the moving plate 4 to form a pressure contact nip portion (fixing nip portion) N.

The pressure roller 6 is rotationally driven by the driving means M in the counterclockwise direction indicated by the arrow. A rotational force acts on the film 5 due to the frictional force between the pressure roller 6 and the outer surface of the film due to the rotational driving of the pressure roller 6, and the film 5 slides in close contact with the lower surface of the film sliding plate 4 to assemble the assembly 1-4. To rotate around.

Film 5 as conductive member (heating member)
Is 10 μm to 100 μm thick polyimide, polyamideimide, PEEK, PES, PPS, PFA, PTFE
-The heat resistant resin such as FEP is used as the base layer 5a, and the base layer 5a
Of the conductive layer 5b on the outer periphery (the surface of the material to be pressure-contacted) of Fe and C
or metal such as Ni, Cu, Cr, etc.
It is formed with a thickness of 0 μm by a treatment such as plating.
Further, as a surface layer on the free surface of the conductive layer 5b, for example, PF
The release layer 5c has a three-layer structure in which a heat-resistant resin having good toner releasability such as A, PTFE, FEP, and silicone resin is mixed or independently coated to form the release layer 5c. In this example, the film base layer 5a and the conductive layer 5b are separate layers, but the film base layer 5a itself may be the conductive layer.

When a current is applied to the exciting coil 2 from the exciting circuit 10, the conductive layer 5b of the film 5 generates heat by electromagnetic induction heating.

Reference numeral 7 is a temperature detecting element which is in contact with the film 5 as a heating member and detects the surface temperature of the film. This temperature detecting element will be described in detail later in (3), but the temperature of the film 5 as a heating member is measured by the temperature detecting element 7, and the exciting circuit 10 of the exciting coil 2 detects the temperature based on the measured temperature. The current value applied to the exciting coil 2 is controlled by the regulator 11 and the temperature of the film 5 (fixing temperature) is appropriately controlled.

Reference numeral 8 is a safety element such as a temperature fuse and a thermoswitch that cut off the energization to the exciting coil 2 when the temperature rises excessively, and is arranged in contact with the core material 1 in this embodiment.

Thus, when the film 5 is rotated by the rotation of the pressure roller 6 and a current is applied from the exciting circuit 10 to the exciting coil 2 to heat the conductive layer 5b of the film 5, the pressure contact nip portion is formed. The recording material P as a heated body is introduced into N and is brought into close contact with the surface of the film 5 and passes through the pressure contact nip portion N together with the film, so that the heat of the film 5 which is electromagnetically heated is recorded. The unfixed toner image T applied to P is heat-fixed T ′. Pressure contact nip N
The recording material P that has passed through is separated from the surface of the film 4 and conveyed. (2) Heating Principle An alternating current is applied to the exciting coil 2 from the exciting circuit 10, whereby an arrow H in FIGS.
The magnetic flux indicated by repeats generation and disappearance. The core material 1 is configured so that the magnetic flux H crosses the conductive layer 5b of the film 5.

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 (FIG. 1).

Due to the skin effect, this eddy current almost concentrates and flows on the surface of the conductive layer 5b on the side of the exciting coil 2, and heat is generated by electric power proportional to the skin resistance R _S of the film conductive layer 5b.

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

[0044]

[Outer 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 5b.
It is presumed that it is difficult to heat when used for
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 2 is preferably 10 to 500 kHz.

When the frequency is 10 kHz or higher, the efficiency of absorption in the conductive layer 5b 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 5b, the skin depth is several μm to several hundred μm.
It is a degree.

When the thickness of the conductive layer 5b is actually less than 1 μm, most of the electromagnetic energy cannot be absorbed by the conductive layer 5b, 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 5b having a thickness of more than 100 μ, the rigidity of the film 5 becomes too high, and heat is transferred by the heat conduction in the conductive layer 5b, so that the releasing layer 5c becomes difficult to warm.

Therefore, the thickness of the conductive layer 5b is 1 to 100 μm.
Is preferred.

In order to increase the heat generation of the conductive layer 5b, I _f
Is increased, and for that purpose, the magnetic flux generated by the exciting coil 2 may be strengthened or the change of the magnetic flux may be increased. As this method, the number of windings of the coil 2 may be increased, or the core material 1 of the exciting coil 2 may be made of ferrite or permalloy having high magnetic permeability and low residual magnetic flux density.

In this embodiment, the core material 1 has an E-shaped cross section.
An exciting coil 2 is wound around this core material 1 along the longitudinal direction of the pressure contact nip portion N, which is a direction substantially orthogonal to the moving direction of the film 5, using a die core material. At the end portions B and C, the magnetic flux concentrates and the amount of heat generation increases, so that the escape of heat at the end portions is compensated.

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

In this embodiment, the conductive layer 5b of the film 5 is formed by plating, but it may be formed by vacuum vapor deposition, sputtering or the like. As a result, aluminum or metal oxide alloy that cannot be plated can be used for the conductive layer 5b. 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 or nickel having a high transmittance is attached, the electromagnetic energy generated by the exciting coil 2 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 5b of the film 5 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 5, 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) 5a.

Further, since it does not depend on the thickness of the film 5, in order to improve the rigidity of the film 5 for speeding up, even if the base material 5a of the film 5 is thickened, it can be quickly heated to the fixing temperature.

Further, since the film base material 5a 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 2 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.

In this embodiment, the direction of the magnetic field is perpendicular to the film 5. However, the magnetic field may be run in the conductive layer 5b parallel to the layer surface.

When a material having a Curie temperature required for fixing is used as a material for forming the conductive layer 5b, the specific heat increases when the Curie temperature approaches the Curie temperature and changes to internal energy, which allows self-temperature control. Become. When the Curie temperature is exceeded, the spontaneous magnetization disappears, whereby the magnetic field generated in the conductive layer 5b decreases below the Curie temperature, and therefore the eddy current decreases and works to suppress heat generation, so that self-temperature control is possible. Become. The Curie point is preferably 100 ° C. to 200 ° C. according to the softening point of the toner.

Alternatively, since the combined inductance between the exciting coil 2 and the film 5 changes greatly near the Curie temperature, it is possible to detect the temperature on the side of the exciting circuit that applies a high frequency to the coil 2 and control the temperature. Is.

As the material of the core material 1 of the coil 2, it is preferable to use one having a low Curie point.

When the conveying operation of the apparatus is stopped and a so-called runaway state where heating control is impossible is performed, the temperature of the core material 1 starts to rise. As a result, the inductance of the exciting coil 2 seems to have increased from the viewpoint of the circuit that generates the high frequency, so when the exciting circuit tries to match the frequency, it gradually changes to the higher frequency side and energy is consumed as power loss in the exciting circuit. As a result, the energy supplied to the coil 2 is reduced and runaway is prevented. Specifically, the Curie point is 100 ° C
It is recommended to select at ~ 250 ° C.

If the temperature is 100 ° C. or lower, the temperature rises even if the temperature is lower than the melting point of the toner and the inside of the film is thermally insulated. Therefore, the runaway prevention is apt to malfunction. In the above embodiment, the film heating is explained, but a heat roller using a core material having low thermal conductivity may be used.

However, since a higher magnetic flux density can be obtained when the exciting coil and the conductive layer are closer to each other, it is preferable to use a thin film heating system of a low thermal conductive substrate.

Although the E-shaped core material 1 is used in the embodiment, I-shaped and U-shaped core materials may be used. In addition, these may be combined, or the dimensions and materials may be changed for each without combining them. (3) Temperature detecting element 7 As described above, the temperature detecting element 7 measures the temperature of the film 5 as a heating member, and the exciting circuit 10 of the exciting coil 2 is controlled by the regulator 11 based on the measured temperature. The current value applied to the exciting coil 2 is controlled, and the temperature of the film 5 (fixing temperature) is properly controlled.

The reason why the temperature of the film 5 is measured in this way is that, when fixing is performed using such a film, the amount of heat supplied to the recording material P greatly changes depending on the temperature of the entire fixing device. Therefore, the amount of heat supplied to the film 5, that is, the AC voltage, the current, the duty, and the frequency applied to the exciting coil 2 are checked while watching the temperature of the film 5 in order to secure the fixing property and prevent the offset due to the excessive heat supply. And so on.

The temperature detecting element 7 for detecting the surface temperature of the film 5 is a thermocouple as a metallic temperature detecting element in this embodiment.

The reason for using the thermocouple 7 is that it has a small heat capacity, good thermal conductivity, and can be adhered to the film 5 by utilizing the spring property of the metal itself. Therefore, it is possible to press-contact the film 5 with a lighter load than a conventional thermistor in which a bead type thermistor is embedded in a sponge, and it is possible to improve the accuracy and responsiveness.

Such a thermocouple 7 is shown in FIG. The thermocouple 7 in this example is a copper-constantan thermocouple. 7a is a copper electrode, 7b is a constantan electrode,
PFA / PTFE to prevent damage and improve rubbing
-It is covered with heat resistant tape 7c such as polyimide.

As the thermocouple 7, in addition to the above-mentioned copper-constantan thermocouple which is usually used, chromel-alumel thermocouple, platinum-10% rhodium thermocouple, platinum-1.
A 3% rhodium thermocouple and any other two kinds of metals may be combined. When such a thermocouple 7 is used as a temperature detecting element, the electromotive force generated in the thermocouple 7 is measured,
The temperature of the film 5 is measured.

Further, the temperature detecting element can use the resistance change of platinum in place of the thermocouple to measure the temperature of the film 5. Also in this case, since the platinum film is very thin and has a small heat capacity and good thermal conductivity, it can be pressed against the film 5 with a light load due to the spring property of the lead electrode, and the accuracy and the responsiveness can be improved. is there. FIG. 3B shows this temperature detecting element.
d is a platinum electrode, 7e and 7f are lead electrodes, and 7c is a heat-resistant coating tape made of PFA, PTFE, polyimide or the like for reinforcing and improving the sliding property.

If the temperature detecting element 7 is brought into contact with the film 5, even if the temperature detecting element 7 is placed in contact with the upper surface (outer surface) of the film 5 as shown by the solid line in FIG. It may be arranged so as to be in contact with the inner surface of.

Further, in the fixing device using such a film, the heat capacity of the pressure roller 6 is large, and the degree of warming of the pressure roller 6 greatly changes the amount of heat supplied to the recording material P.

Therefore, as shown by the three-dot chain line in FIG. 1, the temperature detecting element 7 is arranged in contact with the pressure roller 6 and the surface temperature of the pressure roller 6 is detected to warm the pressure roller 6. Accordingly, it is preferable that the electric power applied to the exciting coil 2 is gradually changed to change the eddy current generated in the film 5 to lower the fixing temperature.

<Embodiment 2> (FIGS. 4 to 6) In Embodiment 1 described above, the temperature detecting element 7 is arranged regardless of the magnetic field formed by the exciting coil 2, but in this embodiment, The temperature detecting element 7 is arranged in the formed magnetic field.

As a result, the temperature detecting element itself also generates heat due to the eddy current. Therefore, it is possible to detect how much energy is applied to the film in the non-contact state with the film 5. This can solve problems such as scratches on the film 5 and an increase in sliding torque caused by bringing the temperature detecting element 7 into contact with the film 5. Therefore, the temperature detecting element 7 itself does not need the protective tape 7c ((a) and (b) in FIG. 3) as in the above-described example.

In order to cause such self-heating, the temperature detecting element 7 is preferably made of metal, such as copper-constantan thermocouple, chromel-alumel thermocouple, platinum-10% rhodium thermocouple, platinum-13. In addition to the% rhodium thermocouple, any two kinds of metals may be combined.
Alternatively, a platinum thin film having a thickness of about 0.1 mm may be used.

These metals are magnetically weak, but when the thickness is in the range of 0.01 mm to 1 mm, the heat capacity is small, and most of the eddy currents are in this thickness due to the skin effect. As it flows, it self-heats sufficiently.

The location of the temperature detecting element 7 is
It may be anywhere in the magnetic field, but more preferably, as shown in FIG.
As shown in FIG.
It is preferable to arrange the pressure contact nip portion N in the pressure contact nip portion N or on the extension line of the pressure contact nip portion N in the longitudinal direction as shown in FIG. In FIG. 6, the pressure contact nip portion N is arranged on the extension line in the longitudinal direction outside the paper passing area. In FIG. 6, the stay 1 and the film 5 are omitted.

When arranged in the pressure contact nip portion N as shown in FIG. 5, the temperature detecting element 7 made of a non-magnetic metal almost generates heat to the heat generating layer 5b of the film 5 made of a magnetic metal or the like. Since the magnetic flux is allowed to pass through without affecting the above, self-heating that accurately corresponds to the actual change in the magnetic flux density can be obtained. And, by design, the pressure contact nip N
Since the change of the magnetic flux density is the largest in the inside, when the temperature is detected by the self-heating, the heat generation becomes the largest, and it becomes close to the actual film.

When the temperature detecting element 7 is arranged on the extension line of the pressure contact nip portion N in the longitudinal direction as shown in FIG. 6, the magnetic flux on the film 5 is not affected. The temperature sensing element 7 may be formed of the non-magnetic metal described above, but more preferably at least one metal of the thermocouple is used as the magnetic metal. With this, even if the magnetic flux density changes the same, a large amount of heat is generated, so that the temperature can be measured more accurately.

Example 3 ((c) and (d) in FIG. 3) Although the metallic temperature detecting element 7 was used in the above-mentioned examples, in the present example, barium titanate, S were used.
A semiconductive temperature sensing element such as iC or Co / Mn / Ni is used.

Since these elements have high resistance, no eddy current is generated. However, if a thin piece of magnetic metal is brought into contact with the element, the same effect as the metallic temperature detecting element 7 can be obtained. Alternatively, by covering the element itself with a magnetic metal, the same effect as that of the above-described embodiment can be expected.

An example of this structure is shown in FIGS. 3 (c) and 3 (d). That is, (c) is a semiconductive so-called thermistor bead 7A covered with a magnetic metal foil 7g,
(D) shows the thermistor beads 7A in contact with a magnetic metal plate 7h. In this example, a heat-resistant and heat-conductive resin adhesive 7i such as a silicone resin is filled between the thermistor beads 7A and the magnetic metal foil 7g or the metal plate 7h, and the magnetic metal foil 7g or the metal plate 7h is connected to the thermistor. The thermal conductivity to the beads 7A is improved. 7j is a lead wire of the thermistor bead 7A.

The arrangement of such a temperature detecting element in the apparatus is in the magnetic field as in the case of the metallic temperature detecting element 7 of the second embodiment.

In the case of the metal-based temperature detecting element 7 described above,
The electromotive force was several mV up to 200 ° C. and could not reach the control level of TTL, C-MOS, etc. without amplification. This makes the circuit complex and expensive.

However, as in this embodiment, metal pieces 7g.7
If a semi-conductive so-called thermistor in contact with h is used, there are several kΩ to several hundred kΩ at room temperature, and several Ω to several kΩ at 100 ° C. or higher. When 5 V is applied as a connection, the divided voltage is 0.about.5 V with a voltage level of 0.
A change of about 01V can be obtained. If this is enough TTL,
Since it can be directly loaded into the ROM and controlled at the level of C-MOS or the like, the circuit is simple and can be achieved at low cost.

<Embodiment 4> (FIG. 7) In this embodiment, the magnetic field generating means and the conductive member are arranged facing each other in the vertical direction, facing each other or in contact with each other, and a field coil plate 12 as a coil. It is an electromagnetic induction heating structure (heater) made of a magnetic metal material 13 as an induction magnetic material. This electromagnetic induction heating structure 12 and 13 is exposed to the magnetic metal material 13 downward so that the film inner surface guide stay 14 formed of a thermosetting resin or the like has a rigidity and heat resistance and has a substantially semi-circular cross section. It is fitted and held along the length of the guide in a substantially central portion of the lower surface.

Reference numeral 15 is an endless heat resistant film, which is loosely fitted onto the film inner surface guide stay 14 including the electromagnetic induction heating structures 12 and 13, and the film 15 is electromagnetically induced by the pressure roller 6. It is pressed against the lower surface of the magnetic metal material 13 of the heating structures 12 and 13.
The film 15 is not provided with a conductive layer.

The pressure roller 6 is rotationally driven in the counterclockwise direction indicated by the arrow by the driving means M, and the film 15 is driven by the frictional force between the roller and the film outer surface due to the rotational driving of the pressure roller 6.
Rotational force acts on the film 15 to cause the film 15 to
It slides and rotates in close contact with the bottom surface of.

The high frequency magnetic field generated from the magnetic field coil of the field coil plate 12 is magnetically coupled to the magnetic metal material 13, and the magnetic metal material 13 is heated by the eddy current loss caused by magnetism,
The heat generation of the magnetic metal material 13 heats the heat-resistant film 15 that closely moves to the magnetic metal material 13.

Then, an image as a material to be heated is fixed between the film 15 and the pressure roller 6 in the pressure contact nip portion N formed by the magnetic metal material 13 and the pressure roller 6 with the film 15 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 15 in the pressure contact nip portion N, so that the heat of the magnetic metal material 13 is applied to the recording material P via the film 15. 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 15 and conveyed.

Also in the apparatus of this example, the same effect can be obtained by disposing the temperature detecting elements as in Examples 1 to 3.

<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 5 serving as an endless belt-shaped conductive member is suspended and stretched between the three members of the lower surface of the stay 3 of 3, the driving roller 16 and the driven roller (tension roller) 17, and the film is driven by the driving roller 16. 5 is rotationally driven. Reference numeral 18 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 5 rotates.

In (b), the electromagnetic induction heating structure 1
A film 5 as an endless belt-shaped conductive member is suspended and stretched between the lower surface of the 2.3 stay 3 and two members of the driving roller 16 and is rotationally driven by the driving roller 16.

In the case of (c), the film 5 as the conductive member is not an endless belt-like one but a long end film wound in a roll is used, and this is an electromagnetic induction heating structure from the feeding shaft 19 side. The body 1, 2, 3 is configured to run at a predetermined speed to the winding shaft 20 side via the stay lower surface.

<Embodiment 6> (FIG. 9) In this embodiment, for example, an outline of an example of an image forming apparatus in which the heating apparatus of the electromagnetic induction heating system of the above-described Embodiment 1 is used as an image heating fixing device (image heating device) 35 It is a block diagram. The image forming apparatus of this example is a laser beam printer using an electrophotographic process.

Reference numeral 21 is a rotary drum type electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum) as an image supporting member (first image supporting member). The photosensitive drum 21 is rotationally driven in the clockwise direction indicated by an arrow at a predetermined peripheral speed (process speed), and in the course of the rotation, the primary charger 22 uniformly charges the negative dark potential V _D.

Reference numeral 23 denotes a laser beam scanner which emits a laser beam L modulated in accordance with a time series electric digital pixel signal of target image information input from a host device such as an image reading device, a word processor and a computer (not shown). The surface of the photosensitive drum 21, which is output and is negatively and uniformly charged by the primary charger 22 as described above, is scanned and exposed by the laser beam, so that the potential absolute value of the exposed portion becomes small and becomes the bright potential V _L , and rotates. An electrostatic latent image corresponding to the target image information is formed on the surface of the exposure drum 21.

Then, the latent image is subjected to reversal development with the powder toner negatively charged by the developing device 24 (laser exposure portion V
Toner is attached to _L ) to make it visible.

The developing device 24 has a developing sleeve 24a which is rotationally driven, and the outer peripheral surface of the developing sleeve 24 is coated with a thin layer of toner having a negative charge to face the surface of the photosensitive drum 21. Absolute value is photosensitive drum 2
By applying the developing bias voltage _VDC which is smaller than the dark potential V _{D of} 1 and larger than the bright potential V _L , the toner on the sleeve 24a is transferred only at the portion of the light potential V _L of the photosensitive drum 21. The latent image is visualized (reversal development).

On the other hand, the recording material (second image carrier, transfer paper) P stacked and set on the paper feed tray 25 is fed out and fed one by one by the paper feed roller 26, and the conveyance guide 2
7, a nip portion (transfer portion) 32 between the photosensitive drum 21 and the transfer roller 30 as a transfer member which is brought into contact with the photosensitive drum 21 and a transfer bias is applied by a power source 31 through the registration roller pair 28 and the pre-transfer guide 29. The toner images on the surface of the photosensitive drum 21 are sequentially transferred onto the surface of the fed recording material P by being fed at an appropriate timing synchronized with the rotation of the photosensitive drum 21. Transfer roller 30 as transfer member
A resistance value of 10 ⁸ to 10 ⁹ Ωm is suitable.

The recording material P that has passed through the transfer portion 32 is separated from the surface of the photosensitive drum 21, and is fixed by the conveyance guide 34 to the fixing device 35.
Then, the transferred toner image is fixed and is output to the discharge tray 36 as an image formed product (print). The surface of the photosensitive drum 21 after the recording material is separated is cleaned by a cleaning device 33.
Then, the residual toner on the surface of the photosensitive drum such as residual toner after transfer is removed, and the surface is cleaned to be repeatedly used for image formation.

[0114]

As described above, according to the present invention, it is possible to improve the accuracy and reliability of the system for controlling the apparatus by detecting the temperature of the required portion of the apparatus for the electromagnetic induction heating type heating apparatus. it can. That is, it is possible to detect a temperature by using a metal temperature detecting element or a temperature detecting element in which a metal piece is integrated, without causing scratches on the subject and without causing sliding resistance. It was

In particular, since the amount of heat actually supplied to the subject can be directly detected by generating an eddy current in the metal and causing the metal to self-heat, it is not affected by variations in the circuit or variations in the contact state of the temperature detecting element. The temperature can be controlled.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a schematic configuration of a heating device (electromagnetic induction heating type / film heating type image heating / fixing device) according to a first embodiment.

FIG. 2 is a perspective view of a core material (magnetic field generation means) and an exciting coil.

3 (a), (b), (c), and (d) are perspective views of configuration examples of temperature detection elements, respectively.

FIG. 4 is a main part diagram of an example in which a temperature detecting element is arranged in the vicinity of a pressure contact nip portion.

FIG. 5 is a main part diagram of an example in which a temperature detecting element is arranged in a pressure contact nip portion.

FIG. 6 is a perspective view of an example in which a temperature detecting element is arranged on an extension line in the longitudinal direction of a pressure contact nip portion.

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]

1.2 Iron core (core material) as magnetic field generating means and exciting coil 3 Film inner surface guide stay 4 Film sliding plate (sliding plate) 5 Film as conductive member (heating member) 5a Film base layer 5b Conductive layer 5c Release layer 6 Pressure roller N Pressure contact nip P Recording material as heated material 7 Temperature detection element 8 Safety element (temperature fuse, thermo switch, etc.)

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Yoji Tomoyuki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Daizo Fukuzawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Kenichi Ogawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (10)

[Claims] 1. An electromagnetic induction heating type heating device for heating a material to be heated by heat generation of the conductive member caused by an eddy current generated in the conductive member by applying a magnetic field to the conductive member by a magnetic field generating means. A heating device characterized in that the arranged temperature detecting element is a metallic temperature detecting element. 2. A heating device of an electromagnetic induction heating system for heating a material to be heated by heat generation of the conductive member due to an eddy current generated in the conductive member by applying a magnetic field to the conductive member by the magnetic field generating means. A heating device characterized in that the arranged temperature detecting element is a metallic temperature detecting element, and is arranged so that a magnetic line of force generated by an exciting coil of the magnetic field generating means enters. 3. An electromagnetic induction heating type heating device for heating a material to be heated by heat generation of the conductive member caused by an eddy current generated in the conductive member by applying a magnetic field to the conductive member by the magnetic field generating means. A heating device characterized in that a metal piece is brought into contact with the arranged temperature detection element. 4. An electromagnetic induction heating type heating device for heating a material to be heated by heat generation of the conductive member caused by an eddy current generated in the conductive member by applying a magnetic field to the conductive member by the magnetic field generating means. A heating device, characterized in that a metal piece is brought into contact with the arranged temperature detecting element so that a magnetic line of force generated by an exciting coil of the magnetic field generating means enters. 5. The conductive member is a fixed member, or a rotating member or a member for traveling and moving, which is an end member.
The heating device according to any one of to 4 above. 6. The conductive member is a laminated member including a conductive layer or a conductive member itself.
The heating device according to any one of to 5 above. 7. 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. 8. The heating device according to claim 7, wherein the pressurizing member is a pressurizing rotary member that is rotationally driven or driven to rotate. 9. The heating target material is a recording material carrying an image to be heat-treated, and is an image heating device for heating the image on the recording material. The heating device according to any one of 1. 10. An image forming apparatus comprising the heating device according to any one of claims 1 to 9 as an image heating device.