JP2000214714A - Fixing roller, fixing device, and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a fixing device of an electromagnetic-induction heating system obtainable an efficiency equal to or higher than that obtained by a fixing device of a heat roller system using a halogen heater, to make the device speedy startable, to prevent the occurrence of a micro-gloss, and to ensure sufficient separation performance even for a medium, such as OHT, which is easy wrap round a fixing roller easily. SOLUTION: The fixing device of an electromagnetic-induction heating system has a fixing roller 1 and a pressure roller 2 being in pressure contact with each other, heats the fixing roller with a magnetic flux generated by a magnetic-flux generation means 3, and, through a pressure contact nip N of both the rollers 1 and 2, sandwiches and carries a recording material P with an unfixed image t held thereon, thereby melting and fixing the unfixed image onto the recording material. The fixing roller 1 comprises at least five layers, which are, from inside toward outside in order, a support layer 11, a sponge layer 12, an electromagnetic-induction heat generation layer 13, an elastic layer 14, and a releasing layer 15. The magnetic-flux generation means 3 is disposed outside the fixing roller 1, and the generated magnetic flux acts on the electromagnetic-induction heat generation layer 13 from the side of the external surface of the fixing roller 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device for fusing and fixing (heating and fixing) an unfixed image on a recording material (media) in an image forming apparatus.

More specifically, the present invention relates to a fixing roller of electromagnetic induction heat generation, a fixing device of an electromagnetic induction heating type having the fixing roller, and an image forming apparatus equipped with the fixing device.

[0003]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a printer, an image forming apparatus such as an electrophotographic process or an electrostatic recording process is formed on a recording material by a transfer method or a direct method by an appropriate image forming process means. As a fixing device for fusing and fixing an image (an image of a heat-fusible developer (toner) composed of a resin, a magnetic material, a colorant, and the like) to a recording material, a heat roller type device is generally used. A heat roller type fixing device nips and conveys a recording material carrying an unfixed toner image at a pressure nip (fixing nip) between a fixing roller (heat roller) and a pressure roller which are pressed and rotated with each other. While applying heat and pressure, the unfixed toner image is melted and fixed, and as a means for heating the fixing roller which is a heat roller, a halogen lamp is built in the fixing roller as a heat source, and the fixing roller is internally mounted with the halogen lamp. , The temperature of the surface of the fixing roller is generally adjusted to a temperature suitable for fixing.

As another means for heating the fixing roller, which is a heat roller, an eddy current is generated in a conductive layer provided on the inner surface of the fixing roller by a magnetic flux from an exciting coil to generate heat in the conductive layer by Joule heat, and the heat is used to fix the conductive layer. There has been proposed a fixing device of an electromagnetic induction heating type in which a roller is heated.

Since the heat source can be placed very close to the toner image in the fixing device of the electromagnetic induction heating system, the temperature of the surface of the fixing roller at the time of starting the fixing device is lower than that of the fixing device using a halogen lamp. It is characterized in that the time required to reach an appropriate temperature for fixing can be shortened. Another feature is that since the heat transfer path from the heat source to the toner image is short and simple, the heat efficiency is high.

A fixing roller for a color copying machine or a fixing roller for a high-speed black-and-white copying machine uses an aluminum cylinder (aluminum cylinder) having a thickness of 3 mm or more as a core, and has an elastic layer of 500 μm or more on the core. An excitation coil is provided inside the core, and the magnetic flux generated by the excitation coil causes the core to generate heat by electromagnetic induction, utilizing the large heat capacity of the core itself to lower the temperature of the fixing roller during continuous paper passing. And the effect of the elastic layer present on the upper layer prevents minute gloss unevenness (micro gloss) on the image and gives a moist feeling of black.

[0007]

However, in the fixing device of the electromagnetic induction heating type in which the exciting coil is provided inside the fixing roller as in the above-mentioned conventional example, in order to efficiently generate heat with the aluminum core, a magnetic flux is required. Even if concentrated current is concentrated in a narrow area and an induced current with a high density is applied, efficient heat generation cannot be obtained (aluminum has a low magnetic permeability μ, so the surface resistance Rs is small and it is difficult to generate heat). When the configuration in which the coil / magnetic core is disposed outside the fixing roller is selected, the gap between the coil and the core increases due to the elastic layer of the fixing roller, and the distance to the core becomes longer. That is, the distance between the coil core and the fixing roller core became long, and it was not possible to obtain the heat generation efficiency equivalent to that of a halogen heater.

Accordingly, an object of the present invention is to provide a fixing roller such as an OHT which has the same or higher efficiency as a heat roller type fixing device using a halogen heater, starts up quickly, does not generate microgloss, and has no microgloss. It is an object of the present invention to provide an electromagnetic induction heating-type fixing device having features such as ensuring sufficient separation performance even for a medium that easily winds.

[0009]

According to the present invention, there is provided a fixing roller, a fixing device, and an image forming apparatus having the following features.

(1) A pressure roller and a pressure contact nip portion are formed, and a recording material carrying an unfixed image is nipped and conveyed in the pressure contact nip portion to melt and fix the unfixed image on the recording material. A fixing roller, comprising at least five layers of a support layer, a sponge layer, an electromagnetic induction heating layer, an elastic layer, and a release layer in order from the inside to the outside.

(2) It has a fixing roller and a pressure roller which are in pressure contact with each other on their surfaces and can rotate freely, and the electromagnetic induction heating layer provided on the fixing roller is heated by the magnetic flux generated by the magnetic flux generating means, thereby fixing the image. An electromagnetic induction heating type fixing device that sandwiches and conveys a recording material carrying an unfixed image at the pressure contact nip between the roller and the pressure roller to fuse and fix the unfixed image on the recording material. In order, the support layer, the sponge layer, the electromagnetic induction heat generating layer, the elastic layer, at least five layers of the release layer, the magnetic flux generating means is disposed outside the fixing roller, the generated magnetic flux from the outer side of the fixing roller A fixing device that acts on an electromagnetic induction heating layer.

(3) The fixing device according to (2), wherein the magnetic flux generating means is disposed along the longitudinal direction of the fixing roller so as to face the fixing roller.

(4) The fixing device according to (2) or (3), wherein the magnetic flux generating means is an exciting coil and a magnetic core.

(5) The magnetic core is arranged along the longitudinal direction of the fixing roller so as to face the fixing roller, and the exciting coil is wound around the longitudinal direction of the fixing roller. The fixing device according to 4).

(6) In an image forming apparatus having an image forming means for forming an unfixed image on a recording material and a fixing means for fusing and fixing the unfixed image formed and carried on the recording material to the recording material, the fixing means is ( An image forming apparatus, which is the fixing device according to any one of 2) to 5).

<Operation> The fixing roller is composed of at least five layers of a support layer, a sponge layer (foam layer), an electromagnetic induction heating layer, an elastic layer, and a release layer in order from the inside to the outside. The magnetic flux generating means is disposed outside the fixing roller, and the generated magnetic flux acts on the electromagnetic induction heat generating layer from the outer surface side of the fixing roller, thereby contributing to heat generation and reducing the heat capacity of the electromagnetic induction heat generating layer for generating an eddy current. Since the heat-generating layer is small and heat-insulated by the sponge layer, it acts to quickly heat the elastic layer or release layer on the surface side of the fixing roller, and the surface of the fixing roller reaches the temperature required for fixing. In addition to the quick arrival, even if heat is taken away by a medium such as paper, the supply of heat can catch up.

Further, the elastic layer is formed as thin as 300 μm in order to form a pressure contact nip between the fixing roller and the pressure roller by utilizing the flexibility of the electromagnetic induction heat generating layer itself thermally insulated by the sponge layer. In this configuration, the nip with a wider width than before can be formed, and the hardness of the fixing roller is smaller than the hardness of the pressure roller. Thus, sufficient separation performance can be ensured even for a medium such as an OHT that does not generate microgloss and is easily wound around a fixing roller.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment (FIG. 1) FIG. 1 is a schematic cross-sectional view of a main part of a fixing device according to the present embodiment.

1 is a fixing roller, 2 is a pressure roller, 3 is a magnetic flux generating means, 4 is a high frequency converter (excitation circuit), 5
Is a temperature sensor, 6 is a control circuit, 7 is a recording material conveyance guide, 8 is a separation claw, P is a recording material, and t is an unfixed toner image on the recording material.

The fixing roller 1 and the pressing roller 2 are vertically arranged in parallel, and both ends are rotatably supported by bearing members (not shown). The pressing roller 2 is not shown using a spring or the like. A pressure nip (fixing nip) N is formed by urging the fixing roller 1 in the direction of the rotation axis thereof by a pressing mechanism and pressing the fixing roller 1 against the lower surface of the fixing roller 1 with a predetermined pressing force. The fixing roller 1 is rotationally driven at a predetermined peripheral speed in a clockwise direction indicated by an arrow by a driving mechanism (not shown). The pressure roller 2 rotates following the rotation of the fixing roller 1 by the frictional force of the pressure contact with the fixing roller 1 at the pressure nip N.

A) Fixing Roller 1 The fixing roller 1 includes a core metal cylinder 11 as a support layer, a sponge layer 12, a conductive layer 13 as an electromagnetic induction heating layer, an elastic layer 14, and a release layer in this order from inside to outside. There are 15 five-layer configurations. The roller hardness is, for example, 30 ° to 70 ° (ASK
Use ER-C 1kg).

In the present embodiment, the core metal cylinder 11 as a support layer is an iron cylinder having an outer diameter of 40 mm and a thickness of 0.7 mm.

The sponge layer 12 keeps the electromagnetic induction heat generating layer 13 thermally insulated, allows the electromagnetic induction heat generation layer 13 to bend, increases the width of the press contact nip N, and makes the roller hardness smaller than that of the pressure roller. The sponge (heat insulating structure) made of a rubber or resin material having heat resistance and elasticity is used, for example, with a thickness of 2 to 10 mm. Is set. In this example, this sponge layer 12 has a thickness of 30 as measured by an Asker rubber hardness tester.
This is a silicone rubber sponge layer having a thickness of 3.9 mm. Adhere with primer if necessary.

In the present embodiment, the conductive layer 13 as the electromagnetic induction heating layer is an endless nickel electroformed belt layer having a thickness of 100 μm. The electromagnetic induction heating layer 13 is made of another material such as a magnetic material (magnetic metal) such as a magnetic stainless steel having a relatively high magnetic permeability μ and an appropriate resistivity ρ.
May be used. Further, among non-magnetic materials, conductive materials such as metals can be used by making the material into a thin film.

The elastic layer 14 serves to enhance the adhesion between the recording material and the surface of the fixing roller, and is a layer of a rubber or resin material having heat resistance and elasticity.
It is set to 0 μm. In this example, the layer is a silicon rubber layer having a thickness of 300 μm once by a JIS-A rubber hardness meter (hardness specified by an A-type hardness meter of JIS K6301).

The outermost release layer 15 is for improving the releasability of the fixing roller surface, and is, for example, a layer of a fluororesin such as PTFE or PFA having a thickness of 10 to 50 μm.

B) Pressure Roller 2 The pressure roller 2 has a 5 mm-thick Si rubber layer 22 on the outer periphery of an iron core 21 having an outer diameter of 20 mm, and a surface release similar to the fixing roller 1. For example, PTF
This is a roller having a total outer diameter of 30 mm provided with a release layer 23 of a fluororesin such as E or PFA having a thickness of 10 to 50 μm.

The pressure roller 2 is approximately 3
The pressure is applied with 0 kg weight. In this case, the nip width of the press contact nip portion N is about 6 mm. Depending on circumstances, the nip width may be changed by changing the load.

C) Magnetic flux generating means 3 The magnetic flux generating means 3 comprises an exciting coil 31 and a magnetic core 32, and is disposed outside the fixing roller 1 so as to face the fixing roller and along the longitudinal direction of the fixing roller. It is.

The magnetic core 32 is an elongated member having an E-shaped cross section and a length dimension substantially corresponding to the longitudinal dimension of the fixing roller 1. The exciting coil 31 has a structure in which a conductive wire is wound around the central projection of the long magnetic core 32 having the E-shaped cross section in the longitudinal direction.

Since the exciting coil 31 is connected to the high-frequency converter 4 and supplied with high-frequency power of 100 to 2,000 [W], the exciting coil 31 uses a thin wire of several litz, and transfers heat to the winding. Considering the case, a heat-resistant material was used for the coating.

The magnetic core 32 has a high magnetic permeability and a low loss. In the case of an alloy such as permalloy, a laminated structure may be used because eddy current loss in the core increases at high frequencies. The core 32 is used for increasing the efficiency of the magnetic circuit and for shielding the magnetic field. The magnetic circuit portion of the coil 31 and the core 32 may be air-core (no core) if there is a means capable of sufficiently shielding the magnetic field.

D) Heating and temperature control of the fixing roller 1 The high frequency converter 4
An alternating current of 100 [kHz] is applied. The magnetic flux induced by the alternating current passes through the inside of the E-shaped magnetic core 32 without leaking to the outside, leaks to the outside of the magnetic core for the first time between the projections of the core, and is a conductive layer which is an electromagnetic induction heating layer of the fixing roller 1. An eddy current flows through the layer 13 and flows through the conductive layer 13, and the conductive layer itself generates Joule heat. The heat generated by the conductive layer 13 heats the fixing roller 1.

The temperature sensor 5 is, for example, a thermistor, and is disposed so as to be in contact with the surface of the fixing roller 1. A detection signal of the fixing roller surface temperature of the temperature sensor 5 is input to the control circuit 6. The control circuit 6 controls the high-frequency converter 4 based on the fixing roller surface temperature detection signal input from the temperature sensor 5 to increase or decrease the power supply from the high-frequency converter 4 to the excitation coil 31, thereby controlling the surface temperature of the fixing roller 1. Is automatically controlled so as to reach a predetermined constant temperature.

E) Fixing operation The fixing roller 1 is driven to rotate, and the pressing roller 2
The conductive layer 13 as the electromagnetic induction heating layer of the fixing roller 1 is electromagnetically heated by the action of the magnetic flux generated by the magnetic flux generating means 3 so that the surface temperature of the fixing roller 1 becomes a predetermined constant temperature. In a controlled state, a recording material P carrying an unfixed toner image t conveyed from an image forming mechanism (not shown) is carried by a conveyance guide 7 in a pressure nip N between the fixing roller 1 and the pressure roller 2. Guided and introduced. In this case, the surface of the recording material P on which the unfixed toner image is formed faces the fixing roller 1.

The recording material P introduced into the pressure nip N between the fixing roller 1 and the pressure roller 2 is conveyed by nipping the pressure nip N, heated by the fixing roller 1 and unfixed toner image t.
Is fused and fixed to the recording material P.

The recording material P that has passed through the pressure nip N is separated from the fixing roller 1 and is discharged and conveyed. The separation claw 8 is disposed in contact with the surface of the fixing roller 1, and forcibly separates the recording material P from the surface of the fixing roller 1 when the recording material P adheres to the surface of the fixing roller 1 after passing through the pressure nip. This is to prevent jam.

As described above, the fixing roller 1 includes the support layer 11, the sponge layer 12, the electromagnetic induction heating layer 13, the elastic layer 14, and the release layer 1 in order from the inside to the outside.
5, the magnetic flux generating means 3 is arranged outside the fixing roller 1, and the generated magnetic flux acts on the electromagnetic induction heat generating layer 13 from the outer surface side of the fixing roller 1 to contribute to heat generation. Since the heat capacity of the electromagnetic induction heat generating layer 13 for generating the eddy current is small and this electromagnetic induction heat generation layer 13 is insulated and held by the sponge layer 12, the elastic layer 14 or the release layer 15 on the surface side of the fixing roller can be quickly formed. And the surface of the fixing roller quickly reached the temperature required for fixing, and the supply of heat was able to catch up even if the heat was taken by the medium P such as paper.

The formation of the pressure contact nip N between the fixing roller 1 and the pressure roller 2 by utilizing the flexibility of the electromagnetic induction heat generating layer 13 which is thermally insulated by the sponge layer 12 prevents the fixing roller 1 from forming. Even if the elastic layer 14 is made as thin as 300 μm, a nip having a width larger than before can be formed, and there is no generation of micro gloss, and sufficient separation performance can be obtained even for a medium such as an OHT which is easily wound around a fixing roller. Can be secured.

Thus, an efficiency equal to or higher than that of a heat roller type fixing device using a halogen heater can be obtained, and a quick start-up can be achieved without generation of micro gloss.
An electromagnetic induction heating-type fixing device having features such as sufficient separation performance can be configured even for a medium such as an OHT that easily winds around the fixing roller.

<Second Embodiment> (FIG. 2) In this embodiment, the magnetic core 32 of the magnetic flux generating means 3 is divided as shown in FIG. In order not to lower the magnetic flux density between the divided magnetic cores and decrease the calorific value,
It is magnetically coupled by a core (not shown).

In the present embodiment, the core 11 of the fixing roller 1 is replaced by an aluminum cylinder having a thickness of 3 mm instead of the iron cylinder having a thickness of 0.7 mm in the first embodiment.

The rest of the configuration of the apparatus is the same as that of the first embodiment, and a description thereof will not be repeated.

The thickness 3 as the core 11 of the fixing roller 1
Although the aluminum cylinder having a thickness of 2 mm has a larger heat capacity than the iron cylinder having a thickness of 0.7 mm, the core 11 of the fixing roller 1 is insulated by the sponge layer 12, so that there is no effect even if the heat capacity is increased.

Further, the electromagnetic induction heating layer 13 is a sponge layer 1.
2, the elastic layer 14 or the release layer 15 on the surface side of the fixing roller 1 acts so as to quickly heat the fixing roller 1 to quickly reach the surface temperature required for fixing. Even if the heat was taken by the medium P such as paper, the supply of heat could catch up.

As long as the material of the core 11 of the fixing roller 1 can secure the strength, it is possible to use a heat-resistant mold pipe such as PPS (polyphenylene sulfide).

The formation of the pressure contact nip N between the fixing roller 1 and the pressure roller 2 by utilizing the flexibility of the electromagnetic induction heat generating layer 13 which is thermally insulated and held by the sponge layer 12 prevents the fixing roller 1 from forming. Even if the elastic layer 14 is made as thin as 300 μm, a nip having a width larger than before can be formed, and there is no generation of micro gloss, and sufficient separation performance can be obtained even for a medium such as an OHT which is easily wound around a fixing roller. Can be secured.

<Third Embodiment> (FIG. 3) In this embodiment, the magnetic core 32 of the magnetic flux generating means 3 is divided as shown in FIG. In order not to decrease the heat generation amount by decreasing the magnetic flux density between the divided magnetic cores,
It is magnetically coupled by a core (not shown).

In this embodiment, as the electromagnetic induction heat-generating layer 13 of the fixing roller 1, a 0.2 mm thick electric resistance welded tube made of SUS (sheet-shaped SUS is formed by rolling a round tubing and welding a seam) )It was used.

Since the electromagnetic induction heating layer 13 is insulated and held by the sponge layer 12, it acts so as to quickly heat the elastic layer 14 or the release layer 15 on the surface side of the fixing roller 1, so that the fixing roller 1 is fixed. Quickly reached the required surface temperature, and even if the heat was taken away by the medium P such as paper, the supply of heat could catch up.

The formation of the pressure contact nip N between the fixing roller 1 and the pressure roller 2 by utilizing the flexibility of the electromagnetic induction heat generating layer 13 which is thermally insulated and held by the sponge layer 12 prevents the fixing roller 1 from forming. Even if the elastic layer 14 is made as thin as 300 μm, a nip having a width larger than before can be formed, and there is no generation of micro gloss, and sufficient separation performance can be obtained even for a medium such as an OHT which is easily wound around a fixing roller. Can be secured.

<Fourth Embodiment> (FIG. 4) This embodiment is an example of an image forming apparatus, and FIG. 4 is a schematic configuration diagram thereof. The image forming apparatus of this embodiment is an electrophotographic four-color printer.

Reference numeral 51 denotes an electrophotographic photosensitive drum (image carrier) made of an organic photosensitive member, which is rotated at a predetermined process speed (peripheral speed) in a counterclockwise direction indicated by an arrow.

The photosensitive drum 51 undergoes a uniform charging process of a predetermined polarity and potential by a charging device 52 such as a charging roller during its rotation.

Next, a laser beam L output from a laser optical box (laser scanner) 53
It undergoes scanning exposure processing of the target image information. The laser optical box 53 outputs laser light L modulated (on / off) in response to a time-series electric digital pixel signal of target image information from an image signal generator such as an image reader (not shown), and outputs the laser light L to the surface of the rotating photosensitive member. The scanning exposure forms an electrostatic latent image on the surface of the rotating photosensitive drum 51 corresponding to the target image information obtained by the scanning exposure. 53a is a laser optical box 53
Is a mirror that deflects the output laser light from the light source to the exposure position of the photosensitive drum 51.

In the case of forming a full-color image, scanning exposure and latent image formation are performed on a first color-separated component image of a target full-color image, for example, a yellow component image. Yellow developing unit 5
The image is developed as a yellow toner image by the operation of 4Y. The yellow toner image is a primary transfer portion T1 which is a contact portion (or a close portion) between the photosensitive drum 51 and the intermediate transfer drum 56.
Is transferred onto the surface of the intermediate transfer drum 56. After the transfer of the toner image to the surface of the intermediate transfer drum 56, the surface of the rotating photoconductor drum 51 is cleaned by the cleaner 57 by removing the adhered residue such as untransferred toner.

The above-described process cycles of charging, scanning exposure, development, primary transfer, and cleaning correspond to the second (for example, magenta component image, magenta developing unit 54M is activated) and the third (for example, cyan) of the desired full-color image. The color separation component image is sequentially executed for each of the component image, the cyan developing device 54C) and the fourth (for example, the black component image, the black developing device 54BK), and the yellow toner image and the magenta toner are formed on the surface of the intermediate transfer drum 56. The four color toner images of the image, cyan toner image and black toner image are sequentially superimposed and transferred, and a color image corresponding to the target full-color image is synthesized and formed.

The intermediate transfer drum 56 has a medium-resistance elastic layer and a high-resistance surface layer on a metal drum, and is in contact with or close to the photosensitive drum 51 and has substantially the same circumference as the photosensitive drum 51. The metal drum is rotated clockwise as indicated by the arrow at a speed, and a bias potential is applied to the metal drum to transfer the toner image on the photosensitive drum 51 to the intermediate transfer drum surface with a potential difference from the photosensitive drum 51.

The color toner image synthesized and formed on the surface of the rotary intermediate transfer drum 56 is transferred to the secondary transfer portion T2, which is a contact nip portion between the rotary intermediate transfer drum 56 and the transfer roller 55, in the secondary transfer portion T2. Recording material (transfer material) fed to the transfer unit T2 from a paper supply unit (not shown) at a predetermined timing
It is transferred to the surface of P. The transfer roller 55 sequentially transfers the composite color toner images collectively from the surface of the intermediate transfer drum 56 to the recording material P by supplying an electric charge having a polarity opposite to that of the toner from the rear surface of the recording material P.

The recording material P that has passed through the secondary transfer portion T2 is separated from the surface of the intermediate transfer drum 56 and introduced into the fixing device A, where the unfixed toner image is heated and fixed to form a color image formed product. The paper is discharged to a paper discharge tray (not shown).

The fixing device A is a fixing device of the electromagnetic induction heating type according to the present invention, for example, the fixing device of the first, second or third embodiment.

After the transfer of the color toner image to the recording material P, the rotating intermediate transfer drum 56 is cleaned by the cleaner 58 by removing the adhered residue such as untransferred toner and paper dust. The cleaner 58 is normally kept in a non-contact state with the intermediate transfer drum 56, and is brought into contact with the intermediate transfer drum 56 in the process of performing the secondary transfer of the color toner image from the intermediate transfer drum 56 to the recording material P. Will be retained.

The transfer roller 55 is also always kept in a non-contact state with the intermediate transfer drum 56. In the process of executing the secondary transfer of the color toner image from the intermediate transfer drum 56 to the recording material P, the intermediate transfer drum 56 Recording material P
Is kept in contact via the.

Note that the fixing device of the present invention also includes an image heating device for heating a recording material carrying an image to improve the surface properties such as gloss and for temporarily attaching the recording material.

[0065]

As described above, according to the present invention, the efficiency of the electromagnetic induction heating type fixing device is equal to or higher than that of the heat roller type fixing device using the halogen heater, and the apparatus is quickly started up. In addition, it is possible to provide such a feature that a sufficient separation performance can be ensured even for a medium such as an OHT which does not generate microgloss and is easily wound around a fixing roller.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a main part of a fixing device according to a first embodiment.

FIG. 2 is a schematic cross-sectional view of a main part of a fixing device according to a second embodiment.

FIG. 3 is a schematic cross-sectional view of a main part of a fixing device according to a third embodiment.

FIG. 4 is a schematic configuration diagram of an example of an image forming apparatus according to a fourth embodiment.

[Explanation of symbols]

 1. Fixing roller 11. Core metal cylinder (support layer) as support layer 12. Sponge layer 13. Electromagnetic heat generating layer 14. Elastic layer 15. Release layer 2. Pressure roller 3. ..Magnetic flux generating means 31.excitation coil 32.magnetic core 4.high-frequency converter (excitation circuit) 5.temperature sensor 6.control circuit 7.recording material transport guide 8.separation claw P .. Recording material t ... unfixed toner image

Claims (6)

[Claims] 1. An electromagnetic induction heating fixing device in which a pressure roller and a pressure contact nip portion are formed, and a recording material carrying an unfixed image is nipped and conveyed in the pressure contact nip portion to fuse and fix the unfixed image on the recording material. A fixing roller, comprising: a roller, a sponge layer, an electromagnetic induction heating layer, an elastic layer, and a release layer, in order from the inside to the outside. 2. A fixing roller, comprising: a fixing roller and a pressure roller, which are in pressure contact with each other on their surfaces and can rotate freely; and heat generated by an electromagnetic induction heating layer provided on the fixing roller by magnetic flux generated by magnetic flux generating means. Is an electromagnetic induction heating type fixing device that nips and conveys the recording material carrying the unfixed image at the nip portion between the pressure roller and the pressure roller, and melts and fixes the unfixed image on the recording material. In order, at least 5 of a support layer, a sponge layer, an electromagnetic induction heating layer, an elastic layer, and a release layer
And a magnetic flux generating means disposed outside the fixing roller so that the generated magnetic flux acts on the electromagnetic induction heating layer from the outer surface of the fixing roller. 3. The fixing device according to claim 2, wherein the magnetic flux generating means is disposed along the longitudinal direction of the fixing roller so as to face the fixing roller. 4. The fixing device according to claim 2, wherein the magnetic flux generating means includes an exciting coil and a magnetic core. 5. The fixing device according to claim 1, wherein the magnetic core is disposed along the longitudinal direction of the fixing roller so as to face the fixing roller, and the exciting coil is wound along the longitudinal direction of the fixing roller. 5. The fixing device according to item 4. 6. An image forming apparatus comprising: an image forming means for forming an unfixed image on a recording material; and a fixing means for fusing and fixing an unfixed image formed and carried on the recording material to the recording material. An image forming apparatus, which is the fixing device according to any one of 2 to 5.