JP2004078114A - Fixing device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device and an image forming device with which stable fixing performance and image quality can be realized without spoiling heating effect by a conveyance part which is provided in front of a fixing means and has a heating body. <P>SOLUTION: A preheating conveyor belt 41 has an endless film 413 conveying a transfer material P and a nearly plane heater 414 which is arranged on the opposite side of the side of the film 413 where the transfer material P is conveyed and heats the transfer material P. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus having a function of forming an image on a recording medium such as a sheet, for example, a copying machine, a printer, or a facsimile apparatus, and more particularly, to a fixing device provided in these apparatuses. It is.
[0002]
[Prior art]
Conventionally, in an image forming apparatus using an electrophotographic technique such as a copying machine or a laser beam printer, an electrostatic latent image is formed by irradiating a laser on a surface of a latent image carrier having a photosensitive layer, and toner is attached to the electrostatic latent image. Then, the toner image is visualized, and the toner image is transferred to a recording medium by electrostatic force to form an image.
[0003]
However, in this state, the toner is merely fixed on the recording medium and is not fixed. Therefore, it is necessary to perform an operation of permanently fixing the toner on the recording medium.
[0004]
As a means for performing this, it is most useful to apply heat so as to melt the powdery toner by applying heat and further press the toner and the recording medium.
[0005]
Generally, in an image forming apparatus using an electrophotographic method, as a means for permanently fixing toner on a recording medium, the fixing device mainly includes two rollers called a fixing roller and a pressure roller. A so-called heat roller type fixing device is used.
[0006]
Each of these roller surfaces is made of elastic rubber, and the surface of the fixing roller, or the surfaces of the fixing roller and the pressing roller are heated to 150 to 200 ° C. by a heater in a hollow cylindrical cored bar of the roller. Is controlled by
[0007]
Further, the fixing roller and the pressure roller are configured to rotate at a constant speed while being in contact with each other by a constant pressure, and the recording medium on which the toner is transferred is directed to the fixing roller side with the toner carrying surface facing the fixing roller. And the nip portion between the pressure roller and the pressure roller, heat and pressure are applied to the toner, and the toner is fixed on the recording medium.
[0008]
In recent years, the performance required for the fixing device has become more and more severe with the increase in color and speed in the market.
[0009]
In a color image, since four colors of toner are used, the absolute amount of toner to be fixed increases. Further, it is necessary to dissolve the toner of each color well to produce a composite color. Therefore, in the color image fixing apparatus, measures such as lowering the melting temperature of the toner to facilitate color mixing, lowering the hardness of the fixing roller and the pressure roller, increasing the fixing nip, and securing the fixing property have been taken. Was.
[0010]
In addition, as the speed increases, the time used for fixing becomes shorter even with the same nip length, so that the amount of heat applied to the recording medium decreases, and the fixing property deteriorates.
[0011]
Therefore, in order to solve the fixing property by increasing the heating time, it has been proposed to perform pre-heating in a so-called transport section in front of the fixing device as disclosed in Japanese Patent Application Laid-Open No. 11-344883, for example.
[0012]
In such an image forming apparatus in which pre-heating is performed before fixing, the recording medium reaches a certain temperature before entering the fixing section, so that the fixing property is remarkably improved.
[0013]
[Problems to be solved by the invention]
However, in the case of the above-described conventional technology, the following problems have occurred.
[0014]
FIG. 5 is a schematic sectional view showing a fixing device 4 'according to the related art.
[0015]
A portion of the conventional preheating conveyance path (hereinafter, referred to as a preheating fixing device) is configured by stretching a belt using rubber or the like over a roller having a built-in heater as shown by reference numeral 41 'in FIG. I was
[0016]
Such a pre-heating fixing device is configured so that the heat of the roller is stored in a rubber belt so that the heat of the entire belt does not easily fall, and it is considered that the recording medium being conveyed is efficiently heated.
[0017]
However, a copier or the like using an electrophotographic apparatus uses various types of paper (recording medium) and thus has different fixing conditions. When many types of paper are used in the same copier, a thick paper is used. There was a problem that if the fixing property was secured, the heating amount would be excessive with thin paper.
[0018]
This was not solved because the heat of the belt was not easily cooled even when the heater inside the roller was turned off, and the difference became more noticeable in an apparatus having a higher image forming speed (hereinafter referred to as a process speed).
[0019]
When the amount of heating becomes excessive in this manner, a phenomenon such as hot offset in which the excessively melted toner image adheres to the fixing roller 42 ′ occurs, and the image deteriorates or stains the fixing device and adheres to the subsequent paper. There was a problem that made the image worse.
[0020]
Even if the hot offset is not reached, the excessively heated toner image has an increased gloss on its surface, resulting in a difference in image quality such as a difference in gloss between thick paper and thin paper.
[0021]
The present invention has been made in order to solve the above-mentioned problems of the related art, and an object of the present invention is to stably fix a heating unit provided in front of a fixing unit without impairing a heating effect by a transport unit having a heating element. It is an object of the present invention to provide a fixing device and an image forming apparatus capable of realizing performance and image quality.
[0022]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention,
Conveying means for conveying the recording medium,
Fixing means for fixing the unfixed toner image transferred on the recording medium conveyed by the conveying means to the recording medium by heating and pressing,
In the fixing device provided with
The transport means,
An endless film for conveying the recording medium;
A substantially planar heating element that is disposed on the side opposite to the side on which the recording medium of the endless film is conveyed and heats the recording medium,
It is characterized by having.
[0023]
It is also preferable to include a control unit for controlling the heat generating operation of the heat generating element according to the type of the recording medium.
[0024]
It is also preferable that the control unit switches on / off of a heating operation of the heating element according to a type of a recording medium.
[0025]
The heating element is divided into a plurality in the transport direction, and a heating operation is performed for each of the plurality of divided heating elements,
It is also preferable that the control means causes a heating element to be heated among the plurality of divided heating elements to generate heat in accordance with a type of a recording medium.
[0026]
The heating element is divided into a plurality in the transport direction, and a heating operation is performed for each of the plurality of divided heating elements,
It is also preferable that the control means is provided in each of the plurality of divided heating elements, and independently performs the heating operation of the plurality of heating elements.
[0027]
The heating element includes a position switching unit that is positioned at any of a position in contact with the endless film and a position separated from the endless film,
The control means operates the position switching means according to the type of the recording medium, the position of the heating element is in contact with the endless film, and the position of the heating element is separated from the endless film It is also suitable to be located at either one.
[0028]
It is also preferable that the heating element is divided into a plurality of parts in the transport direction, and a heating operation is performed for each of the plurality of divided heating elements.
[0029]
It is also preferable to include a position switching unit that positions the heating element at one of a position in contact with the endless film and a position apart from the endless film.
[0030]
It is also preferable that the endless film is provided with at least two rotators that are arranged on the side opposite to the side on which the recording medium is conveyed and that drives the endless film.
[0031]
It is also preferable that the endless film includes a conductive layer and a resistance layer.
[0032]
It is also preferable that the recording medium is electrostatically conveyed by applying a charge to the surface of the resistance layer or the surface of the recording medium conveyed thereon with respect to the reference potential of the conductive layer.
[0033]
The image forming apparatus includes an image forming unit that forms a toner image on a recording material, and the above-described fixing device that passes the recording material on which the toner image is formed.
[0034]
BEST MODE FOR CARRYING OUT THE INVENTION
Preferred embodiments of the present invention will be illustratively described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment should be appropriately changed depending on the configuration of the apparatus to which the invention is applied and various conditions. It is not intended to limit the scope to the following embodiments.
[0035]
(First Embodiment)
FIG. 2 is a schematic configuration diagram showing an electrophotographic color copying machine which is an embodiment of the image forming apparatus according to the first embodiment of the present invention.
[0036]
Reference numeral 1 denotes a process unit which constitutes an image forming means for forming an image, and includes 1Y, 1M, 1C, and 1B for each color of yellow, magenta, cyan, and black, and forms each color.
[0037]
Since the configuration of the process unit 1 is the same except for the toner color, the image forming process will be described using 1Y of the yellow station.
[0038]
Reference numeral 11 denotes a photoconductor as an image carrier, which has a photoconductive layer on the surface of a conductive substrate such as aluminum, and rotates in the direction of arrow X.
[0039]
Reference numeral 12 denotes a primary charger, which applies an AC + DC bias to a rubber roller having a medium resistance to uniformly negatively charge the surface of the photoconductor 11.
[0040]
An exposure device 13 exposes the surface of the uniformly charged photoreceptor 11 into an image obtained by decomposing a color image for each color to form an electrostatic latent image.
[0041]
A developing device 14 develops the electrostatic latent image on the photoconductor 11 with yellow toner and visualizes the developed electrostatic latent image.
[0042]
Reference numeral 2 denotes a transfer belt, which electrically attracts and conveys a transfer material P as a recording medium conveyed from the paper cassette 3 to the belt surface, and is disposed on the opposite side of the photoconductor 11 of each process unit with the belt interposed therebetween. The toner image formed on the photoconductor 11 is electrostatically transferred onto the transfer material P by the bias applied to the transfer blade 21.
[0043]
Reference numeral 15 denotes a cleaning device that scrapes off the toner remaining on the surface of the photoconductor 11 after the transfer of the toner image, and makes the photoconductor 11 usable again for image formation.
[0044]
Reference numeral 4 denotes a fixing device that fixes the transfer material P to which each color has been transferred by heat and pressure, and fixes the toner on the transfer material P. The fixing device 4 has the characteristic configuration of the present embodiment, and will be described later in detail.
[0045]
Hereinafter, a sequence of the entire apparatus according to the present embodiment will be briefly described by taking a case of copying in a full color mode as an example.
[0046]
When copying is started, first, the primary charger 12 uniformly charges the photoconductor 11.
[0047]
Subsequently, the exposure device 13 exposes the color-separated image exposure obtained by reading the document on the document table 5 to form a first color yellow electrostatic latent image on the photoconductor 11.
[0048]
Next, in the developing section, the electrostatic latent image is visualized by the developing device 14, and a yellow toner image is formed on the photoconductor 11.
[0049]
In a similar image forming process, toner images corresponding to the respective colors are formed on the photoconductors of the magenta, cyan, and black process units 1M, 1C, and 1B.
[0050]
On the other hand, a transfer material P of a size corresponding to the document is fed from the paper cassette 3 by the transport roller 31 at the same time as the toner image, and is electrostatically attracted onto the transfer belt 2.
[0051]
The transfer material P adsorbed on the transfer belt 2 is conveyed to a transfer section in contact with the photoconductor 11 in accordance with the toner image of each process unit, and the toner images are sequentially transferred onto the transfer material P by a bias applied to the transfer blade 21. To form a full-color image.
[0052]
The transfer material P on which the full-color image has been formed is separated at the end of the transfer belt and conveyed to the fixing device 4.
[0053]
In the fixing device 4, the toner of each color superimposed on the transfer material P is mixed by heat and pressure to bind to the transfer material P, and is discharged to the discharge tray 6 as a full color print.
[0054]
Next, a fixing device which is a feature of the present embodiment will be described in detail.
[0055]
FIG. 1 is a schematic configuration diagram illustrating an example of a fixing device having the features of the present embodiment.
[0056]
The fixing device 4 includes a fixing unit 42 similar to a conventional roller fixing device having a fixing / pressing roller, and a pre-heating and conveying unit 41 having a heat source on the upstream side in the fixing paper conveying direction. It is divided into two parts. Here, the fixing unit 42 forms a fixing unit, and the pre-heating and conveying unit 41 forms a conveying unit.
[0057]
The pre-heating / conveying unit 41 stretches the endless film 413 between two rollers of a driving roller 411 and a tension roller 412 as rotating bodies arranged in parallel with each other, and between the two rollers on the back side of the film 413. It is constituted by a flat heater 414 as a substantially flat heating element arranged and in contact with the film 413.
[0058]
The film 413 has a multilayer structure in which a conductive layer and a release layer (resistive layer) in units of several μm are sequentially coated on the surface of a film of several to several tens μm formed endlessly of a polyimide resin.
[0059]
The conductive layer of the film 413 is grounded by an electrical connection (not shown), and the transfer material P is electrostatically charged by applying a charge between the release layer which is also an insulating layer or the transfer material P further thereon. It can be stably conveyed by stable suction.
[0060]
Furthermore, the release layer, which is the outermost surface, is controlled in releasability so that the heated first side image can be prevented from adhering to the film during double-sided printing.
[0061]
The driving roller 411 is formed in a roller shape by winding a rubber having large friction around a cored bar so that the film 413 can be driven without slipping.
[0062]
The tension roller 412 is tensioned by a spring (not shown) on the front side in the transport direction with respect to the drive roller 411, and holds the film 413 so that slack or wrinkling does not occur.
[0063]
The flat heater 414 is formed by printing a resistor on a ceramic, and is coated with glass to improve the surface slidability. The temperature of the flat heater 414 is controlled by a temperature detecting element 415 disposed on the back side thereof.
[0064]
The fixing unit 42 follows a conventional roller fixing device, and includes an upper fixing roller 421 and a lower pressure roller 422 in the figure. The fixing roller 421 and the pressure roller 422 each have a halogen lamp 424 disposed inside a hollow Al roller, and are independently temperature-controlled by a temperature detecting element 425.
[0065]
The fixing roller 421 has an Al hollow roller surface coated with a silicone rubber layer 423 as an elastic layer. Since the silicone rubber layer 423 is in direct contact with the toner image on the transfer material P, the silicone rubber layer 423 must have good releasability from the melted toner. In addition, it is necessary to set the hardness to a certain level so that it can be elastically deformed by the pressing force from the pressure roller 422 to form a nip required for fixing.
[0066]
The pressure roller 422, like the fixing roller 421, coats a hollow aluminum roller with a silicone rubber layer 423 and arranges a halogen lamp 424 inside to perform heating and pressure. In the pressing, the fixing roller 421 fixes the center axis position, while the pressing roller 422 uses a spring (not shown) to move the center axis position between the center of the fixing roller 421 and the center of the pressing roller 422. Is pressed along the line connecting.
[0067]
Here, the feature of the present embodiment lies in the configuration of the preheating portion. By making the member of the pre-heating portion a thin film + a flat heater, the responsiveness of the heating to the transfer material P is increased, and the ON / OFF of the heating depending on the thickness of the transfer material P provides a stable fixing property. Image quality can be obtained.
[0068]
Conventionally, as shown in FIG. 5, since the pre-heating is performed by a combination of a thick belt and a heat roller including a halogen heater, the response of the heating to the transfer material P is poor. It was difficult to make a choice. For this reason, if the fixing property is satisfied for thick paper having poor fixability (which indicates a thicker transfer material P), the amount of heat for pre-heating is excessive when the paper is thinner (which indicates a thinner transfer material P). In addition, there is a possibility that an image defect such as an increase in gloss due to excessive heating or a hot offset may occur.
[0069]
In the present embodiment, a film 413 having a low heat capacity of 80 μm is used for the belt, and a flat heater 414 is arranged over the entire conveyance path on the back surface of the belt so that the transfer material P can be reliably heated even with the belt having a low heat capacity. ing. Also, the flat heater 414 is made as thin as possible with a thickness of 0.6 mm to reduce the heat capacity, thereby improving the thermal response to power ON-OFF.
[0070]
The ON-OFF of the flat heater 414 may be controlled by a control unit according to the type of the transfer material P specified by the user by specifying the type of the transfer material P such as the thickness on the operation panel. Alternatively, a detecting means for detecting the type and characteristics of the transfer material P, such as the thickness, may be provided, and the control means may control the detecting means in accordance with the detection result.
[0071]
Further, the operation of the flat heater 414 may be controlled not only in the ON-OFF but also in the temperature stepwise.
[0072]
When an image was formed with the configuration of the present embodiment, it was possible to achieve both the fixing property of thick paper and the prevention of excessive overheating of thin paper without lowering the process speed only by turning on and off the flat heater 414 of the pre-heating unit. Further, there was no difference in gloss depending on the paper type, and good image formation could be performed.
[0073]
That is, even if different types of recording media enter the fixing device, heating can be performed with an appropriate heating amount, and stable fixing properties and image quality can be obtained regardless of the types of recording media.
[0074]
Further, by forming the film 413 into a two-layer structure of a conductive layer and an insulating layer and electrostatically transporting the recording medium, the adhesion between the film 413 and the recording medium is improved, and the recording medium can be reliably heated.
[0075]
(Second embodiment)
FIG. 3 shows a second embodiment. This embodiment shows another embodiment of the first embodiment, and is an improvement of the fixing device 4 shown in the first embodiment.
[0076]
FIG. 3 is a schematic sectional view showing an example of the fixing device according to the present embodiment, and has the same composition as FIG. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.
[0077]
In the present embodiment, the heat quantity of the pre-heating is improved so that it can be more finely controlled.
[0078]
The plane heater 414 of the first embodiment is used to convey the heat amount of the pre-heating portion so that an appropriate heat amount can be applied not only to the thick paper and the thin paper but also to the transfer material P having a thickness therebetween. It is divided into multiple parts in the direction.
[0079]
By performing ON-OFF control of the plurality of divided flat heaters according to the type of the transfer material P, such as the thickness, the amount of heat suitable for the thickness of the transfer material P can be supplied. Note that the plurality of divided plane heaters may be operated stepwise.
[0080]
Reference numerals 414a to 414e denote heaters obtained by dividing the flat heater 414 of the first embodiment into five parts in the transport direction. Temperature sensors 415a to 415e are arranged in each of the heaters and controlled at a constant temperature. The five plane heaters are lit for 0 to 5 heaters for each thickness of the transfer material P, and the amount of heat for preheating is controlled in six stages.
[0081]
The same effect can be obtained by controlling the temperature of the flat heater 414 of the first embodiment to five levels, but the temperature of each heater can be reduced by dividing the heater and controlling the temperature at a constant temperature. It is possible to stabilize and suppress the variation in heating of the paper as compared with the case where the temperature of the entire heater of the first embodiment is controlled.
[0082]
Further, in order for the effect of the pre-heating to function effectively, the shorter the distance between the heat source of the pre-heating and the fixing unit 42 at the subsequent stage (downstream in the transport direction), the better. It is desirable to increase 414a-414b-414c-414d-414e in order from the one closer to.
[0083]
When an image is formed with the configuration of the present embodiment, not only thick paper and thin paper, but also appropriate preheating can be applied to a transfer material having a thickness between them, and the type of transfer material, particularly the thickness, It became possible to respond more finely.
[0084]
As described above, by dividing the flat heater into a plurality of parts and controlling each of them individually, finer heating control can be performed for the type of recording medium, and more stable fixing properties and image quality can be obtained.
[0085]
(Third embodiment)
FIG. 4 shows a third embodiment. This embodiment shows another embodiment of the above-described embodiment, and is an improvement of the fixing device 4 shown in the first embodiment.
[0086]
FIG. 4 is a schematic cross-sectional view showing an example of the fixing device according to the present embodiment, and has the same composition as FIG. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.
[0087]
The present embodiment is configured to cope with a higher process speed.
[0088]
If the process speed is increased with the configuration as in the first embodiment, there is a possibility that the effect of the pre-heating may remain slightly when pre-heating is not performed after the pre-heating is continuously used. .
[0089]
This is because the heat capacity of the flat heater 414 is a problem. The flat heater heated under the influence of the continuous preheating ON during the continuous thick paper has no time to cool down due to the high process speed, and the thin paper is conveyed. If this occurs, a change in gloss will occur.
[0090]
This is because the flat heater 414, which is a heating element, is 5 to 10 times thicker than the thickness of the film 413 used for the belt, so that its heat capacity cannot be ignored.
[0091]
Therefore, in the present embodiment, the flat heater 414 is configured to be mechanically separated from the film 413 so that the preheating effect can be quickly turned off even when the process speed is high.
[0092]
When the preheating is ON, the plane heater 414 energized at the position in contact with the film 413, that is, at the position A indicated by the dotted line in FIG. It is configured to be cooled at a place where the transfer material P inside is not affected.
[0093]
For this reason, even when the process speed is increased, thin paper or the like to be conveyed with preheating OFF is not affected by heat, and can be fixed with a predetermined amount of heat.
[0094]
Here, the cam 416 constitutes a position switching unit. The operation of the cam 416 may be controlled by the control unit when, for example, the process speed is equal to or higher than a predetermined speed and no preheating is performed after the preheating is continuously used.
[0095]
When an image was formed using the configuration of the present embodiment, a stable image having a predetermined gloss could be obtained without excessive heating even when thin paper was passed after continuous thick paper.
[0096]
In this way, by allowing the flat heater to be separated from the film, the temperature can be controlled without worrying about the heat capacity of the heating element even in an image forming apparatus having a high process speed, and stable fixing properties and image quality corresponding to a high speed can be achieved. Quality can be obtained.
[0097]
【The invention's effect】
As described above, according to the present invention, there is provided a fixing device and an image forming apparatus capable of realizing stable fixing properties and image quality without impairing a heating effect provided by a conveying unit having a heating element provided in front of a fixing unit. To provide.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a fixing device according to a first embodiment of the present invention.
FIG. 2 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention.
FIG. 3 is a schematic configuration diagram of a fixing device according to a second embodiment of the present invention.
FIG. 4 is a schematic configuration diagram of a fixing device according to a third embodiment of the present invention.
FIG. 5 is a schematic configuration diagram of a fixing device using a pre-heating and conveying belt according to the related art.
[Explanation of symbols]
1 (1Y, 1M, 1C, 1B) Process unit 11 Photoreceptor 12 Primary charger 13 Exposure device 14 Developing device 15 Cleaning device 2 Transfer belt 21 Transfer blade 3 Paper cassette 31 Transport roller 4 Fixing device 41 Preheating transport belt 411 Drive Roller 412 Tension roller 413 Films 414, 414a to 414e Planar heaters 415, 415a to 415e Temperature detecting element 416 Cam 42 Fixing section 421 Fixing roller 422 Pressure roller 423 Silicone rubber layer 424 Halogen lamp 425 Temperature detecting element 5 Document table 6 Output tray P Transfer material

Claims (12)

Conveying means for conveying the recording medium,
Fixing means for fixing the unfixed toner image transferred on the recording medium conveyed by the conveying means to the recording medium by heating and pressing,
In the fixing device provided with
The transport means,
An endless film for conveying the recording medium;
A substantially planar heating element that is disposed on the side opposite to the side on which the recording medium of the endless film is conveyed and heats the recording medium,
A fixing device comprising: The fixing device according to claim 1, further comprising a control unit configured to control a heating operation of the heating element according to a type of a recording medium. The fixing device according to claim 2, wherein the control unit switches on / off of a heating operation of the heating element according to a type of a recording medium. The heating element is divided into a plurality in the transport direction, and a heating operation is performed for each of the plurality of divided heating elements,
The fixing device according to claim 2, wherein the control unit causes a heating element to be heated among the plurality of divided heating elements to generate heat in accordance with a type of a recording medium. The heating element is divided into a plurality in the transport direction, and a heating operation is performed for each of the plurality of divided heating elements,
4. The fixing device according to claim 2, wherein the control unit is provided in each of the plurality of divided heating elements and independently performs a heating operation of the plurality of heating elements. 5. The heating element includes a position switching unit that is positioned at any of a position in contact with the endless film and a position separated from the endless film,
The control means operates the position switching means according to the type of the recording medium, the position of the heating element is in contact with the endless film, and the position of the heating element is separated from the endless film The fixing device according to claim 2, wherein the fixing device is located at any one of the positions. 2. The fixing device according to claim 1, wherein the heating element is divided into a plurality of heating elements, and a heating operation is performed for each of the plurality of divided heating elements. 3. 2. The fixing device according to claim 1, further comprising a position switching unit that positions the heating element at one of a position in contact with the endless film and a position separated from the endless film. 3. apparatus. 9. The endless film according to claim 1, further comprising at least two rotating members disposed on a side opposite to a side on which the recording medium is conveyed, and driving the endless film. Item 6. The fixing device according to item 1. The fixing device according to claim 1, wherein the endless film includes a conductive layer and a resistance layer. 11. The recording medium according to claim 10, wherein the recording medium is electrostatically conveyed by applying a charge to the surface of the resistive layer or the surface of the recording medium conveyed thereon with respect to the reference potential of the conductive layer. Fixing device. 12. An image forming apparatus comprising: an image forming unit that forms a toner image on a recording material; and the fixing device according to claim 1 that passes the recording material on which the toner image is formed. apparatus.

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