JP2002116644A - Heat fixing-device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide, in view of a problem of the use of an induction heat system, a heat fixing-device which decreases a temperature rise of an induction coil, improves heat efficiency of a heating rotational body, prevents dielectric breakdown of the induction coil, is highly safe, is easy to obtain an installation space for a heat releasing means used for the induction coil, and provides a high degree of freedom in installation position. SOLUTION: In the heat fixing-device having the heating rotational body 1 which generates heat by an induction current, the induction coil 3 which generates a magnetic flux supplied to the heating rotational body 1, and at least one means 4 which releases heat generated by the induction coil 3, the induction coil 3 and the heat releasing means 4 for the induction coil 3 are provided outside the heating rotational body 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat fixing device for paper and film, and more particularly to a heat fixing device used for an image forming apparatus such as a copying machine, a printer, a facsimile machine, and the like.

[0002]

2. Description of the Related Art An image forming apparatus using an electrophotographic method is:
Usually, a recording material electrostatically carrying toner consisting of a resin, a magnetic material, a coloring material, etc. is nipped and conveyed by a pressure contact portion (nip portion) of a fixing roller and a pressure roller which are pressed and rotated with each other. While applying heat and pressure to the toner image, the fixing device fixes the toner image on the recording material. As a heating method in such a fixing device, there is an induction heating method using a high frequency (for example, Japanese Patent Application Laid-Open No. Sho 59-33787).
No.). In a fixing device using this induction heating method, an induction coil is concentrically arranged inside a hollow fixing roller made of a metal conductor, and a high-frequency magnetic field generated by flowing a high-frequency current through the induction coil causes the fixing roller to rotate. An induced eddy current is generated, and the fixing roller itself generates heat by the skin resistance of the fixing roller itself.

According to a fixing device of an induction heating system, an electric
Since the heat conversion efficiency is extremely improved and the heat generation source can be located very close to the toner, the temperature of the fixing roller surface during starting of the fixing device is lower than that of the conventional heat roller method using a halogen lamp. It is characterized in that the time required to reach an appropriate temperature for fixing (warm-up time) can be shortened.

However, the above-mentioned conventional electromagnetic induction heating type fixing device in which an eddy current is generated in a conductive layer provided on a fixing roller by magnetic flux generated by an induction coil and heat is generated by Joule heat generally has an induction coil built in the fixing roller. Because there is an induction coil inside the fixing roller that becomes hot,
There is a problem that the temperature rises due to heat generated by its own electric resistance and the power efficiency is reduced. Also, the coating of the induction coil made of resin is melted by heat,
There is also a problem that the insulation of the induction coil is impaired. In addition, when the fixing roller needs to be replaced due to an accident or life, it takes time and effort to remove the induction coil, which requires time for replacement and increases service cost. On the other hand, there is a type in which a thin metal sleeve having a boundary is used as a heating member instead of the fixing roller, but the above situation is the same.

In order to solve such a problem, for example, as disclosed in Japanese Patent Application Laid-Open No. 54-39645, a cooling mechanism for blowing air into a fixing roller or the like is provided to suppress the temperature rise of the induction coil. A proposal has been made.

However, when the air is blown, not only the induction coil and the core but also the inner surface of the fixing roller is cooled by the air, so that there is a problem that the fixing ability is impaired due to a decrease in the temperature of the roller itself. .

[0007] Instead of such a method, a heat fixing device is provided in which a heat radiating means in contact with the induction coil is provided to suppress a rise in temperature in the induction coil and prevent a rise in power consumption, thereby obtaining good heating performance. (For example, Japanese Patent Application Laid-Open No. H11-251053). Further, a heating and fixing device has been proposed in which an induction coil for generating a magnetic flux is provided outside the rotating body to facilitate replacement of the rotating body and to improve heating efficiency (for example, see, for example, Japanese Patent Application Laid-Open No. H11-163873).
JP-A-11-297462).

[0008]

As described above, when the temperature of the induction coil rises in the fixing of the induction heating method, the electric resistance of the induction coil increases, and the power consumption increases. In addition, there is a possibility that dielectric breakdown of the induction coil occurs. Even if the induction coil is located only outside, it is easier to dissipate heat than when it is inside. However, if no heat radiating means is provided, the cooling efficiency is poor and the temperature rise of the induction coil cannot be suppressed. In addition, when the induction coil is inside the fixing roller, a method of cooling air from one of the fixing rollers or conducting heat to the outside of the fixing roller with a heat radiating plate or the like to cool the fixing roller has been proposed. Difficult to cool down. Further, there is a problem that the inner surface of the fixing roller is cooled and the heating efficiency is reduced.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems in the conventional heat fixing device and the image fixing device using the same.
In view of the problem when using the induction heating method, it is an object of the present invention to provide a heat-fixing device that reduces the temperature rise of the induction coil, improves the heating efficiency of the heating rotator, does not cause insulation breakdown of the induction coil, and has high safety. First, to provide a heating and fixing device that can easily secure a space for mounting the heat radiating means of the induction coil and have a high degree of freedom in mounting position, and second, to provide a heating and fixing device with high cooling efficiency of the induction coil. Third, to provide a heat-fixing device having a large surface area for heat dissipation and high cooling efficiency, fourth, to provide a heat-fixing device in which a heat-dissipating member does not easily generate heat, and fifth, to reduce cost. Fifth, to provide a heating and fixing device with high cooling efficiency of the induction coil, and sixth, to provide a high cooling efficiency of the induction coil and a high heating efficiency of the heating rotator. C To provide an energy-saving type heat fixing device capable of shortening the warm-up time and an image forming apparatus using the same. Seventh, the cooling efficiency of the induction coil can be increased, the performance is stable, the heating efficiency is high, and the recording material is high. And an image forming apparatus using the same. The eighth aspect is to provide a heat fixing apparatus having high induction coil cooling efficiency, stable temperature control and good image quality, and an image forming apparatus using the same. Ninth is to provide a heat fixing device having high cooling efficiency of an induction coil, stable temperature control, good heating efficiency, an energy saving type and low noise, and an image forming apparatus using the same. .

[0010]

According to the first aspect of the present invention,
A heating and fixing device provided with at least one heating rotator that generates heat by an induction current, an induction coil that generates a magnetic flux to be supplied to the heating rotator, and a unit that dissipates heat generated in the induction coil; The heat radiation means of the induction coil is provided outside the heating rotator.

According to a second aspect of the present invention, in the heat fixing device of the first aspect, at least one heat radiating means is provided in direct or indirect contact with the induction coil.

According to a third aspect of the present invention, in the heat fixing device according to the second aspect, the radiating means in contact with the induction coil is a radiating fin.

The invention according to claim 4 is the invention according to claim 2 or 3.
Wherein the heat radiating means in contact with the induction coil is a non-magnetic, high heat conductive member.

According to a fifth aspect of the present invention, in the heat fixing device of the fourth aspect, a part of the material of the heat radiating means is made of a high heat conductive material such as aluminum or copper.

According to a sixth aspect of the present invention, in the heat fixing apparatus according to any one of the second to fifth aspects, at least one radiating means is in direct or indirect contact with the induction coil. An air cooling fan for cooling the means is provided.

According to a seventh aspect of the present invention, there is provided a heating and fixing device according to one of the first to sixth aspects.

According to an eighth aspect of the present invention, in the image forming apparatus according to the seventh aspect, a structure is provided in which the airflow of the air cooling fan does not directly hit the non-recording material.

According to a ninth aspect of the present invention, in the image forming apparatus according to the seventh aspect, the airflow of the air cooling fan is not directly applied to the temperature sensor.

The invention according to claim 10 is the invention according to claims 7 to 9
In the image forming apparatus described in any one of the above, the air cooling fan is provided in the non-sheet passing portion.

The invention according to claim 11 is the invention according to claims 7 to 1
0, wherein the air flow rate of the air-cooling fan is variable.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic sectional view of a heat fixing device for explaining an embodiment of the present invention. In FIG. 1, the heat fixing device includes a fixing roller 1 and a pressure roller 2 that can work together by bringing a part of the peripheral surface into contact with each other.

The fixing roller 1 shown in FIG.
m, composed of a hollow cylinder made of iron with a thickness of 0.8 mm, and on the surface, for example, a thickness of 10 to 50 μm in order to enhance releasability.
And a layer of PFA having a thickness of 10 to 50 μm. Further, a layer having low thermal conductivity such as foamed silicone rubber may be provided as an insulating layer on the inner surface of the iron hollow cylinder.

The pressure roller 2 is constituted by providing a silicone rubber elastic layer having a thickness of 2 to 3 mm on the outer periphery of an aluminum core having an outer diameter of 40 mm. The fixing roller 1 and the pressure roller 2 are rotatably provided, so that only the fixing roller 1 is driven. Accordingly, the pressure roller 2 can be driven to rotate by the printing force at a pressure contact portion (hereinafter, referred to as a fixing nip portion) while being pressed against the surface of the fixing roller 1. The pressure roller 2 is pressed in the rotation axis direction of the fixing roller 1 by a mechanism (not shown) using a spring or the like.

In the configuration shown in FIG. 1, the pressure roller 2
The load is 5 kgf. In this case, the width of the press contact portion (nip width N) is set to about 7 mm. The nip width can be changed by changing the load. The induction coil 3 is disposed along the outer peripheral surface of the fixing roller 1, and is held by a shape holding member (not shown) in the configuration shown in FIG. This induction coil 3 has 1
An alternating current of 0 to 100 KHz is applied, and a magnetic field induced by the alternating current causes an eddy current to flow through the conductive layer of the fixing roller 1 to generate Joule heat. In order to increase the heat generation, it is desirable to arrange the induction coil 3 as close as possible to the outer peripheral surface of the fixing roller 1 as long as the mechanical accuracy allows. It is also possible to improve the heat generation efficiency by reducing the number of turns of the induction coil 3 to locally apply a strong magnetic field to the conductive layer, or by increasing the frequency of the alternating current.

The temperature of the induction il 3 rises due to Joule heat due to the resistance of the coil itself and natural heat radiation from the fixing roller. Therefore, when the temperature of the induction coil 3 increases, the electric resistance of the induction coil 3 increases, and the heating efficiency decreases. Therefore, a heat radiating means is required to lower the temperature of the induction coil 3. In the configuration shown in FIG.
An air-cooling fan 4 is used as a heat-dissipating means, and the air-cooling fan 4 blows and cools the induction coil 3.

When the air cooling fan 4 is used, the induction coil 3
Is located inside the fixing roller 1, the airflow of the air cooling fan 4 flows from one side of the fixing roller 1 to the other, so that a temperature gradient is likely to occur in the axial direction of the fixing roller 1. In addition, since the inside of the fixing roller 1 is also cooled, the temperature of the fixing roller 1 is prevented from rising, and the heating efficiency is reduced. However, in the configuration shown in FIG. 1, since the induction coil 3 is disposed outside the fixing roller 1,
The mounting position of the air cooling fan 4 and the direction of the airflow by the air cooling fan 4 can be designed relatively freely.
Therefore, the temperature gradient in the axial direction of the fixing roller 1 can be reduced. Further, since the air is not directly blown to the fixing roller 1, it is less likely that the fixing roller 1 is directly cooled, and the heating efficiency of the fixing roller 1 does not decrease. The way of winding the induction coil 3 is not limited to the one shown in the following figures, and if the induction coil 3 is arranged outside the heating rotator such as the fixing roller 1,
There is a similar effect. As the heat dissipating means, in addition to the air cooling fan 4 shown in FIG. 1, a heat dissipating plate, a heat dissipating fin, a heat pipe, a Peltier element, or the like can be used.

The surface temperature of the fixing roller 1 is detected by a temperature sensor 5 provided in contact with the surface, and the power supply to the induction coil 3 can be increased or decreased according to a detection signal of the surface temperature. Accordingly, the surface temperature of the fixing roller 1 is maintained at a constant temperature. A transport guide 6 is provided near the position where the fixing roller 1 and the pressure roller 2 face each other. The transport guide 6 applies the transfer paper S transported while carrying the unfixed toner image to the fixing roller 1. It is guided to a fixing nip portion with the pressure roller 2.

A separation claw 7 is disposed at a position where the transfer paper S has passed through the fixing nip portion between the fixing roller 1 and the pressure roller 2, and the separation claw 7 is in contact with or close to the surface of the fixing roller 1. The transfer paper S that has been heated and fixed is peeled off from the surface of the fixing roller 1.

In the configuration shown in FIG. 1, when the fixing roller 1 is driven to rotate and an alternating current is applied to the induction coil 3, the temperature at the fixing nip between the two rollers rises.
The temperature is monitored using the temperature sensor 5. In this state, the transfer paper S carrying the unfixed toner image is guided by the conveyance guide 6 and introduced into the fixing nip portion, and is conveyed with the rotation of the fixing roller 1 so that the toner image is formed by the heat of the fixing roller 1 and the nip pressure. It is fused and fixed to the transfer paper S.

FIG. 2 is a view for explaining another configuration relating to the embodiment of the present invention. The configuration shown in FIG. 2 uses a radiating member by heat transfer as a direct or indirect cooling means for the induction coil 3. It is characterized by being used. When a heat radiating plate or a heat radiating fin 8 is used as a heat radiating member capable of conducting heat in contact with the induction coil 3, the fixing roller 1
The induction coil 3 is moved without moving the air nearby.
Can be released, so that the temperature of the fixing roller 1 does not decrease. In the configuration shown in FIG. 2, an example is shown in which the radiation fin 8 is in direct contact with the induction coil 3, but the shape holding member (not shown) of the induction coil 3 is sandwiched between the radiation fin 8 and the induction coil 3. May be. Further, the heat radiation fins 7 may also serve as shape holding members for the induction coil 3. From the viewpoint of heat conduction, it can be said that it is preferable to also serve as the shape holding member of the induction coil 3 because the number of components can be reduced and direct conduction is possible. The radiating fins 8 are desirable because they have a large surface area and higher radiating efficiency than a radiating plate.

The material of the heat radiating plate or the heat radiating fins 8 should be non-magnetic so as not to generate heat due to the magnetic field generated by the induction coil 3 and should be a high heat conducting member so as to efficiently radiate heat. Desirable, aluminum,
Copper, aluminum oxide, aluminum nitride, silicon carbide, or the like is used. In particular, aluminum and copper are generally used materials and are preferable materials because they are inexpensive and have good workability.

FIG. 3 is a view for explaining still another configuration according to the embodiment of the present invention. The configuration shown in FIG. 3 is a cooling member for the induction coil 3, which is a heat dissipating member directly in contact with the induction coil 3. And an air cooling fan for further cooling the heat radiating member. In this configuration, the cooling fan 4 cools the heat radiating member (the heat radiating fin 8 is shown in FIG. 3 for convenience, but may be a heat radiating plate), so that the cooling efficiency can be further improved. When the airflow of the air cooling fan 4 directly hits the transfer paper on which the final fixed image is adhered, the unfixed image is scattered or the transfer paper fluctuates, and is not stably conveyed to the fixing roller 1 and the pressure roller 2. Therefore, wrinkles may be generated on the paper. Therefore, it is necessary to prevent the airflow of the air cooling fan 4 from directly hitting the transfer paper on which the unfixed image is adhered. For this reason, in the configuration shown in FIG. 3, the wind shield member 9 is provided near the transfer paper S that advances toward the fixing nip. Without limiting to such a configuration, an airflow guide member may be provided, and the air cooling fan 4 and the induction coil 3 may be provided.
Alternatively, it may be performed by appropriately arranging the radiation fins 8 and the like. Further, when the airflow of the air cooling fan 4 directly hits the temperature sensor 5, the detected temperature becomes unstable due to the influence, and it may be difficult to keep the surface temperature of the fixing roller 1 stable. As a result, the fixing property of the image is not stable, causing a problem. Therefore, the airflow of the air cooling fan 4 is prevented from directly hitting the temperature sensor 5 so that the fixing roller 1
It is desirable to be able to perform stable temperature detection.
For this purpose, the above-described air-cooling fan 4, induction coil 3,
It is desirable that the arrangement of the radiation fins 8 and the temperature sensor 5 and the like be made appropriate and that an airflow guide member and a wind shield member be provided.

FIG. 4 is a view for explaining still another configuration according to the embodiment of the present invention. The configuration shown in FIG. 4 is characterized in that a cooling member for the induction coil 3 is extended to a non-sheet passing portion. And In FIG. 4, a heat radiating plate 10, which is a heat radiating member serving as a cooling member provided in contact with the induction coil 3, is disposed in a non-paper passing portion in the axial direction of the fixing roller 1, in other words, outside the roller end portion. The air-cooling fan 4 is arranged as a cooling member of the heat sink 10 so as to face the extended portion. Air cooling fan 4
Is located at the non-sheet passing portion of the fixing roller 1, so that the airflow does not directly hit the temperature sensor 5 and the transfer sheet S. In this configuration, since the air-cooling fan 4 is located in a place that is hardly affected by the magnetic field generated by the induction coil 3, the air-cooling fan 4 does not generate heat and does not lower the cooling efficiency. Since the air-cooling fan 4 can be cooled with an air volume suitable for the temperature by making the air volume variable, the temperature control can be finely controlled and the temperature can be made more stable. Also, since the air volume does not increase unnecessarily, noise that increases in proportion to the air volume can be suppressed, and the device can be made quieter.

FIG. 5 is a view for explaining still another configuration according to the embodiment of the present invention. The configuration shown in FIG. 5 is a heat fixing device having any one of the configurations shown in FIGS. The apparatus is applied to an image forming apparatus. In FIG. 5, the image forming apparatus includes a drum-shaped photoconductor 11 forming a latent image carrier,
Around the device 1, a charging device 12, an image writing device 13, a developing device 14, a transfer device 15, and a cleaning device 16 that perform image forming processing along the rotation direction are arranged.

After the photosensitive drum 11 is uniformly charged by the charging device 12, an electrostatic latent image is formed by the image writing device 13, and the visible image processing of the electrostatic latent image is performed by the developing device 14. The toner image is transferred onto a transfer sheet S fed from a sheet feeding device (not shown). The transfer device 15 shown in FIG. 5 uses a transfer belt wrapped around a pair of rollers. The transfer paper S on which the toner image on the photosensitive drum 11 is transferred by the transfer charge induced on the transfer belt is used. The sheet is conveyed toward the heat fixing device 17. The transfer paper S after the transfer is fixed by performing heat fusion of the toner image in the heat fixing device 17 and is discharged toward a discharge tray (not shown).

[0036]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment based on the above configuration will be described below.
In the configuration shown in FIG. 1, the fixing roller 1 has an outer diameter of 50 m.
m, a hollow cylinder made of iron having a thickness of 0.8 mm, and a release layer using a PTFE layer having a thickness of 30 μm is provided on the surface. The pressure roller 2 is provided with an elastic layer made of silicone rubber having a thickness of 3 mm on the outer periphery of a core made of aluminum. The pressure roller 2 is brought into contact with the fixing roller 1 with a load of 45 kgf using a spring, and the width of the fixing nip portion (nip width N) is about 7 mm. The induction coil 3 has the fixing roller 3 arranged along different surfaces, and is held by a shape holding member (not shown).

The induction coil 3 is heated by applying an alternating current of 60 KHz. The air cooling fan 4 is arranged at the axial center of the fixing roller 1 and cools the induction coil 3. A temperature sensor 5 is disposed at the axial center of the fixing roller 1 so that the surface temperature of the fixing roller 1 at the fixing nip is 18
When the temperature was controlled so as to be 0 ° C., the surface temperature difference at both axial ends of the fixing roller 1 was 2 ° C. or less. The power required to maintain the surface temperature of the fixing roller near the fixing nip at 180 ° C. was 570 W.

The present inventor has described the embodiment of the above configuration with
The surface temperature difference was compared by a configuration in which an induction coil was provided inside the fixing roller 1 and the induction coil was cooled by an air-cooling fan from one axial direction of the fixing roller 1 to the other. In contrast to the temperature difference of 2 ° C. as described above, in the latter configuration, a result of 16 ° C. was obtained, and it was clear that the difference was larger than the surface temperature difference according to the present embodiment. Regarding the power for maintaining the surface temperature of the fixing roller 1, when the cooling by the air-cooling fan 4 is not performed, the result is that 680W higher than 570W in the present embodiment is required. . next,
Another embodiment of the present invention will be described. In the configuration shown in FIG. 2, the power for maintaining the temperature near the fixing nip portion of the fixing roller 1 at 180 ° C. was measured using the aluminum radiating fins 8, and a result of 520 W was obtained.

Next, another embodiment of the present invention will be described. In the configuration shown in FIG. 3, the fixing roller 1 has an outer diameter of 5 mm.
0mm, 0.8mm thick iron hollow cylinder,
A release layer using a PTFE layer having a thickness of 30 μm on the surface has already been obtained. The pressure roller 2 has an outer diameter of 40 mm,
An elastic layer made of silicone rubber having a thickness of 3 mm is provided on the outer periphery of a core made of aluminum. The pressure roller 2 is in contact with the fixing roller 1 at 45 kgf using a spring, and the width of the fixing nip (nip width N) is about 7 mm. The induction coil 3 is provided along the outer peripheral surface of the fixing roller 1 and is held by a shape holding member (not shown). The radiation fins 8 are made of aluminum, and the wind shield 9 is made of a heat-resistant resin. 60 for induction coil 3
An alternating current of KHz was applied to heat the fixing roller 1.
The air cooling fan 4 is installed at the axial center of the fixing roller 1 and cools the induction coil 3. A temperature sensor 5 is arranged at the center of the fixing roller 1 in the axial direction, and the surface temperature of the fixing roller 1 near the fixing nip is 180 ° C.
The power required to maintain the fixing roller surface temperature near the fixing nip at 180 ° C. was 490 W. The temperature detected by the temperature sensor 5 was stable and could be easily controlled. In addition, 10
Although 0 sheets were passed, no paper wrinkles were generated.

The present inventor compared this embodiment with the case where the wind shield member 9 shown in FIG. 3 was not provided. As a result, the temperature detected by the temperature sensor 5 became unstable due to the airflow from the air cooling fan 4. The result was that the temperature control became unstable. Further, the transfer paper fluttered due to the airflow from the air cooling fan 4, and paper wrinkles occurred on 11 out of 100 sheets.

Next, still another embodiment of the present invention will be described. In the configuration shown in FIG. 4, the fixing roller 1 is formed of an iron hollow cylinder having an outer diameter of 40 mm and a thickness of 0.7 mm, and a release layer made of a 20 μm thick PTFE layer is provided on the surface. The pressure roller 2 has an outer diameter of 40 mm, and is provided with an elastic layer made of silicone rubber having a thickness of 3 mm on the outer periphery of an aluminum core. Pressure roller 2
Is in contact with the fixing roller 1 at 40 kgf using the spring of the fixing roller 1, and the width of the fixing nip (nip width N) is about 7 mm. The induction coil 3 is provided along the outer peripheral surface of the fixing roller 1 and is held by aluminum radiating fins 8. One end of the radiation fin 8 is set to be long so as to protrude from the fixing roller 1, and the air cooling fan 4 is arranged opposite to the protruding portion to be cooled. A temperature sensor is attached to a part of the radiation fin 8 so that the air flow of the air cooling fan 4 can be adjusted according to the temperature detected by the temperature sensor 5.

An alternating current of 60 KHz was applied to the induction coil 3 to heat the fixing roller 1. A temperature sensor 5 was disposed at the center of the fixing roller 1 in the axial direction, and the surface temperature of the fixing roller 1 at the fixing nip was controlled to be 180 ° C.
The power required to maintain 80 ° C. was 480 W.
Further, since the airflow of the air cooling fan 4 does not directly hit the temperature sensor 5 of the fixing roller 1, the detection temperature of the temperature sensor 5 is stable and can be easily controlled. Further, since the airflow of the air cooling fan 4 does not directly hit the transfer paper S,
No flapping occurred on the transfer paper S, and no paper wrinkles occurred after 100 sheets were passed. Further, as the temperature of the radiation fins 8 decreased, the number of revolutions of the air-cooling fan 4 also decreased, and the noise decreased.

The heating system and the cooling structure for the heating system shown in the above configuration are not limited to the fixing device. For example, the transfer paper carrying the image may be heated to obtain a glossy or glossy image. It is also possible to apply the present invention to an apparatus for reforming or borrowing a sheet, or an apparatus for feeding and drying a sheet-shaped member.

[0044]

According to the first aspect of the present invention, (1) a heating rotator that generates heat by an induced current, an induction coil that generates a magnetic flux to be supplied to the heating rotator, and radiates heat generated in the induction coil. In the heating device provided with at least one means, since the induction coil and the heat radiation means of the induction coil are outside the heating rotator,
It is possible to efficiently reduce the temperature rise of the induction coil, improve the heating efficiency of the heating rotator, and obtain a highly safe heating fixing device without causing dielectric breakdown of the induction coil. Moreover,
It is easy to secure a space for mounting the heat radiating means of the induction coil, and it is possible to obtain a heat fixing device having a high degree of freedom in mounting position.

According to the second aspect of the present invention, since at least one heat radiating means is in direct or indirect contact with the induction coil, it is possible to obtain a heating and fixing device having a high cooling efficiency for the induction coil. .

According to the third aspect of the present invention, since the heat radiating means in contact with the induction coil is a heat radiating fin,
It is possible to obtain a heat fixing device having a large heat radiation surface area and high cooling efficiency.

According to the fourth aspect of the present invention, since the member of the heat radiating means in contact with the induction coil is a non-magnetic and high heat conductive member, it is possible to obtain a heat fixing device in which the heat radiating member does not easily generate heat. .

According to the fifth aspect of the present invention, since the material of the heat radiating means is made of at least aluminum or copper, the cost can be reduced. According to the invention as set forth in claim 6, at least one heat radiating means is directly or indirectly in contact with the induction coil and the air cooling fan for cooling the heat radiating means is provided.
Further, it is possible to obtain a heat fixing device having a high cooling efficiency of the induction coil.

According to the seventh aspect of the invention, it is possible to obtain an energy-saving type image forming apparatus in which the cooling efficiency of the induction coil is high, the heating efficiency of the heating rotator is high, and the warm-up time is short.

According to the eighth aspect of the present invention, since the airflow of the air cooling fan does not directly hit the non-recording material, the cooling efficiency of the induction coil is further increased, the temperature maintaining performance is stabilized, and the heating efficiency is improved. In addition, obtaining an image forming apparatus in which wrinkles and the like are less likely to occur on the recording material is a matter of k.

According to the ninth aspect of the present invention, since the airflow of the air cooling fan is prevented from directly hitting the temperature sensor, an image forming apparatus having high cooling efficiency of the induction coil, stable temperature control and good image quality can be provided. It is possible to obtain.

According to the tenth aspect of the present invention, since the air cooling fan is provided in the non-sheet passing portion, the air flow of the air cooling fan does not directly hit the recording material and the temperature sensor.
By improving the cooling efficiency of the induction coil, it is possible to obtain an image forming apparatus in which wrinkles are not generated on the recording material, the temperature control is stable, and the image quality is high.

According to the eleventh aspect of the present invention, since the air volume of the air-cooling fan is variable, the cooling efficiency of the induction coil can be further increased, the temperature control is stable, the heating efficiency is good, the energy saving type is noise-free. It is possible to obtain a small number of image forming apparatuses.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an example of a configuration according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing another example of the configuration according to the embodiment of the present invention.

FIG. 3 is a schematic diagram showing another example of the configuration according to the embodiment of the present invention.

FIG. 4 is a schematic diagram showing still another example of the configuration according to the embodiment of the present invention.

FIG. 5 is a schematic diagram showing still another example of the configuration according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixing roller 2 Pressure roller 3 Induction coil 4 Air cooling fan 5 Temperature sensor 8 Radiation fin 9 Wind shield member 10 Heat radiating plate 11 Photoconductor drum 15 Transfer device 17 Fixing device

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Claims (11)

[Claims] A heating rotator that generates heat by an induced current; an induction coil that generates a magnetic flux to be supplied to the heating rotator;
A heat fixing device provided with at least one means for radiating heat generated in the induction coil, wherein the induction coil and a heat radiation means for the induction coil are provided outside a heating rotator. Heat fixing device. 2. The heat fixing device according to claim 1, wherein at least one heat radiating means is provided in direct or indirect contact with said induction coil. 3. The heat fixing device according to claim 2, wherein the heat radiating means in contact with the induction coil is a heat radiating fin. 4. The heat fixing device according to claim 2, wherein the heat radiating means in contact with the induction coil is a non-magnetic, high heat conductive member. 5. The heat fixing device according to claim 4, wherein a part of the material of the heat radiating means is made of a high heat conductive material such as aluminum or copper. 6. The air-cooling fan according to claim 2, wherein at least one heat radiating means is in direct or indirect contact with the induction coil, and further cools the heat radiating means. A heat fixing device comprising: 7. An image forming apparatus using the heat fixing device according to claim 1. Description: 8. The image forming apparatus according to claim 7, wherein the air flow of the air cooling fan does not directly hit the non-recording material. 9. The image forming apparatus according to claim 7, wherein the airflow of the air cooling fan does not directly hit the temperature sensor. 10. The image forming apparatus according to claim 7, wherein an air cooling fan is provided in the non-sheet passing portion. 11. The image forming apparatus according to claim 7, wherein the air flow of the air cooling fan is variable.