JP2020076821A - Fixing device and image forming apparatus - Google Patents

Abstract

To provide a fixing device that reduces the risk of damage to a member without impairing fixability that is an original function, can detect rotation of a fixing member without an increase in size and complexity, and is safe, inexpensive, and excellent in controllability.SOLUTION: A fixing member 2 is provided with a conductive area 21 on its surface. The fixing member 2 is further provided with electrodes 61, 62 that are in slide contact with the fixing member and applied with a feeble voltage (for example, 5 V or less) not causing a trouble in toner fixation. When the conductive area 21 is brought into contact with both the electrodes 61, 62 in association with rotation of the fixing member 2, electric conduction is established between the electrodes 61, 62. The electric conduction (electric conduction signal) is input to a control unit, and the control unit determines the state of rotation of the fixing member based on the periodic electric conduction signal.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a fixing device and an image forming apparatus including the fixing device.

  Generally, as a fixing device used in an image forming apparatus, a fixing device including an endless tubular fixing member (for example, a fixing belt) and a pressure member (for example, a pressure roller) is known. In such a fixing device, a nip portion (fixing nip) is formed by the fixing member and the pressure member, and the toner is pressed and heated in the nip portion to fix the toner on the recording paper.

  In the fixing device having such a configuration, if the heat source heats the fixing member while the fixing member is not rotating, the fixing member may be heated too much in some cases and expands to cause plastic deformation. However, there is a problem that the temperature detection means malfunctions.

  Therefore, a fixing device provided with a rotation detecting means for detecting the rotation state of the fixing member has been proposed. However, the rotation detecting means itself includes a roller or an impeller that rotates following the rotation of the fixing member and a photo sensor. It is composed, and there is a problem that it becomes large and complicated.

  Japanese Unexamined Patent Application Publication No. 2016-133750 discloses a fixing device for determining whether or not the fixing belt is rotating by using a simple structure. In the fixing device, a hole is provided in a part of the elastic layer of the fixing member in the circumferential direction, and the temperature sensor determines that the temperature increases and decreases periodically as a rotating state.

  However, this configuration has a problem that when a high temperature stable state is obtained due to continuous paper feeding or the like, a temperature difference between the base material layer and the elastic layer is difficult to appear, and cannot be used for rotation determination. There is also a problem in that the fixing member is extremely easily broken from the hole provided in the elastic layer as a starting point.

  INDUSTRIAL APPLICABILITY The present invention can detect the rotation of the fixing member without impairing the fixing property which is the original function, reducing the risk of member damage, and increasing the size and complexity of the member. An object of the present invention is to provide an excellent fixing device and image forming apparatus.

  In order to solve this problem, the present invention includes a rotatable fixing member, a pressure member that is pressed against the fixing member to form a nip portion, and a heating source that heats the fixing member. In a fixing device for fixing an unfixed toner image on a recording material by passing a recording material carrying an unfixed toner image onto the conductive material, it is detected that the conductive area provided on the fixing member is electrically connected to the conductive area. And a control unit to which a detection signal from the conduction detecting unit is input.

  In the fixing device and the image forming apparatus of the present invention, the rotation of the fixing member can be detected without impairing the fixing property which is the original function, suppressing the risk of member damage, and increasing the size and complexity. It is possible to provide a fixing device and an image forming apparatus that are safe, inexpensive, and excellent in controllability.

1 is a cross-sectional configuration diagram showing an example of a fixing device according to an exemplary embodiment of the present invention. FIG. 6 is a cross-sectional view showing a holding member that holds a fixing member. FIG. 3 is a perspective view illustrating a configuration example of a rotation detection unit of the fixing device. FIG. 6 is a perspective view showing another configuration example of rotation detection means of the fixing device. FIG. 3 is a block diagram showing a configuration example of a control system relating to determination of a rotation state of a fixing member. It is a timing char which shows the detection cycle for every linear velocity. FIG. 3 is a cross-sectional view showing the configuration of the image forming apparatus according to the embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional configuration diagram showing an example of a fixing device according to an embodiment of the present invention. The fixing device 1 includes a fixing member 2, a heating source 3, a pressure member 4, a nip forming unit 5, and the like.

  The fixing member 2 is, for example, a metal belt such as nickel or SUS (stainless steel) or a belt formed of a resin material such as polyimide in an endless tube shape, and may be a film. The surface layer of the belt has a releasing layer such as a PFA or PTFE layer which is a thermoplastic resin, and has a releasing property so that toner does not adhere. An elastic layer formed of a silicone rubber layer or the like may be provided between the base material of the belt and the PFA or PTFE layer. When there is no silicone rubber layer, the heat capacity becomes smaller and the fixability is improved, while when the unfixed image is crushed and fixed, the fine irregularities on the belt surface are transferred to the image and the surface of the image has a distorted surface. The uneven glossiness (discolored skin image) tends to remain. In order to improve this, it is preferable to provide a silicone rubber layer of 100 μm or more. Due to the deformation of the silicone rubber layer, minute irregularities are absorbed, and the image of the discolored skin is improved.

  A supporting member (stay) 6 for supporting the nip forming means 5 is provided inside the fixing member 2 to prevent the nip forming means 5 from being bent under the pressure of the pressure member 4 and to ensure a uniform nip in the axial direction. You can get the width.

  Further, the fixing device 1 includes the reflecting member 7 between the heating source 3 and the supporting member 6, and wasteful energy consumption due to heating of the supporting member 6 by radiant heat from the heating source 3 is suppressed. There is. Here, instead of providing the reflection member 7, the same effect can be obtained by performing heat insulation or mirror surface treatment on the surface of the support member 6.

  The heating source 3 may be a halogen heater as shown, but may be an IH (induction heating means), a resistance heating element, a carbon heater, or the like. The fixing member 2 is directly heated by the heating source 3 from the inner peripheral side. When the heating source 3 is a halogen heater, the fixing device 1 may have a light shielding plate. The light shielding plate shields the light emitted by the halogen heater so that the fixing member 2 is heated within a range according to the recording paper size. The light-shielding plate has a light passage portion corresponding to various recording paper sizes, and by rotating, for example, an appropriate light passage portion is positioned between the heating source 3 and the fixing member 2. ..

  The pressure member 4 is provided with an elastic rubber layer 4B on the outside of the core metal 4A, and a release layer (PFA or PTFE layer) (not shown) is provided on the surface of the elastic rubber layer 4B to obtain releasability. ing. The pressure member 4 rotates by receiving a driving force from a driving source such as a motor provided in the image forming apparatus 100 (shown in FIG. 3) described later via a gear. The pressure member 4 is pressed (pressed against) to the fixing member 2 side by a spring or the like, and has a predetermined nip width when the elastic rubber layer 4B is crushed and deformed.

  The pressure roller as the pressure member 4 may be a hollow roller or may have a heating source such as a halogen heater. The elastic rubber layer may be solid rubber, but sponge rubber may be used when there is no heater inside the pressure roller. It is more preferable to use sponge rubber because the heat insulating property is improved and the heat of the fixing sleeve is less likely to be taken away.

  The nip forming means 5 is arranged inside the fixing member 2, that is, on the opposite side of the pressing member 4 with the fixing member 2 interposed therebetween. As a result, the nip portion N (fixing nip) is formed by the fixing member 2 and the pressing member 4 which are arranged to face each other. The recording paper onto which the toner image has been transferred passes through the nip portion N, and is heated and pressed to fix the toner image on the recording paper. Although the shape of the nip portion N is flat in FIG. 1, it may be a concave shape or another shape (the concave shape of the nip portion causes the discharge direction of the leading edge of the recording paper to be closer to the pressure roller). And the occurrence of jams is suppressed because the separability is improved).

  On the surface of the nip forming means 5, a fabric member 8 impregnated with a lubricant is provided. The fabric member 8 is provided so as to contact the inner surface (the surface on the side of the nip forming unit 5) 2b of the fixing member 2 and constitutes a contact portion. Further, the fabric member 8 supplies the lubricant to the inner surface 2b of the fixing member 2 and also functions as a supply unit. Examples of the lubricant include silicone oil and grease.

  The fixing member 2 rotates with the rotation of the pressure member 4. In the mode shown in FIG. 1, the pressing member 4 is rotated by the driving source, and the driving force is transmitted to the belt at the nip portion N, whereby the fixing member 2 is rotated. The fixing member 2 is sandwiched and rotated by the nip portion N, and the holding member (9A, 9B) is inserted and guided at both side end portions other than the nip portion N to run.

  The fixing device 1 further includes a pair of holding members 9A and 9B as shown in FIG. The holding members 9A and 9B each include a plate-shaped base portion 91 and a holding projection 92 that projects from the base portion 91. The holding protrusion 92 is formed, for example, in a cylindrical shape, is arranged inside the fixing member 2, and is in sliding contact with the inner surface 2b. The pair of holding members 9A and 9B guide the rotation while holding the fixing member 2 at both ends in the width direction by inserting the holding protrusions 92 at both ends in the width direction (axial direction) of the fixing member 2.

  With the above-described configuration, it is possible to realize a fixing device that is inexpensive and that warms up quickly.

Next, a configuration example of the rotation detecting means of the fixing device in the present invention will be described.
The rotation detecting unit of the fixing device 1 according to the embodiment includes the conduction detecting unit 104 (electrodes 61, 62 or 63, 64) and the conductive region 21 or 22. In the configuration example of FIG. 3, the conductive region 21 is provided on the surface layer side of the fixing member 2. Further, in the configuration example of FIG. 4, a conductive region 22 is provided on the back surface side of the fixing member 2.

  In FIG. 3, a metal foil as a conductive area 21 is provided on the surface layer outside the paper passing area of the fixing member 2. Further, in the vicinity of the holding member 9A (9B) which holds the fixing member at both ends in the axial direction, electrodes 61 and 62 to which a weak voltage (for example, 5 V or less) having no problem in toner fixing is applied while slidingly contacting the fixing member 2 are provided. Has been. The electrodes are made of a carbon-based material that has excellent conductivity and slidability.

  The conductive region 21 is provided so as to have a predetermined size in the circumferential direction of the fixing member 2. In order to detect the conductive region 21, a plurality of (two in this example) electrodes 61 and 62 are arranged at different positions in the circumferential direction of the fixing member 2 (so that the positions in the circumferential direction are different). . The weak voltage is applied between the electrodes 61 and 62 as described above. The conductive region 21 moves as the fixing member 2 rotates, and when the conductive region 21 contacts both the electrodes 61 and 62, the electrodes 61 and 62 are electrically connected. This conduction (conduction signal) is input to the control unit (FIG. 5) described later, and the control unit determines that the conduction has occurred. That is, the control unit detects / determines electrical conduction between the plurality of electrodes via the conductive region 21.

  In addition, when the conductive region 21 is not in contact with any of the electrodes 61 and 62, and when the conductive region 21 is in contact with only one of the electrodes 61 and 62, there is conduction between the electrodes 61 and 62. do not do.

  According to this configuration, the fixing member 2 is rotated by the pressure source 4 that also serves as a drive source while being heated by the heating source 3, but only the region where the conductive region 21 is sandwiched by the electrodes 61 and 62 during rotation (rotation). The conduction is detected only when the conductive region 21 is sandwiched between the electrodes 61 and 62. Since the conduction timing deviates at each rotation cycle according to the target conveyance speed, if the fixing member 2 is not rotated together, the conduction timing may be deviated, or non-conduction or conduction may be maintained, and the rotation detection means. Can function as However, since there is some slippage during warm-up and during paper passage, there is a range of judgment. The rotation may be detected by preparing a table for each linear velocity zone of the fixing device. If the control unit that performs the determination is installed in the machine body (image forming apparatus) in which the fixing device is mounted, the fixing device can be downsized.

  FIG. 4 is an example of a configuration in which the base material layer of the fixing member 2 is formed of a metal layer such as SUS or nickel. Electrodes 63 and 64 are embedded on the sliding surface of the fixing member 2 of the holding member 9B (9A). In the conductive region 22, the inner surface coating is partially removed, and the base material layer is exposed on the inner surface side. That is, the conductive region 22 is provided on the back surface side of the fixing member 2. Even in such a configuration, it can function as the rotation detecting means (the conduction detecting means 104 is omitted in FIG. 4).

  In the case of the configuration of FIG. 4, the electrodes constituting the conductivity detecting means do not have to be brought close to one side of the fixing member holding member, and one electrode may be arranged on each side in the axial direction. In that case, the portions (conductive areas 22) where the inner surface coating is removed and the base material layer is exposed may be formed on both sides of the fixing member.

  According to the above-described configuration, the size and complexity of the periphery of the fixing device are avoided, and since it is not necessary to provide holes in the elastic layer or the base material layer that bears most of the thickness of the fixing member, damage such as damage is prevented. Problems can be suppressed.

FIG. 5 is a block diagram showing a configuration example of a control system related to determination of the rotation state of the fixing member. Here, a configuration example using the control unit of the image forming apparatus in which the fixing device is mounted is shown.
In FIG. 5, a memory 102 is connected to a control unit 101 provided in the main body of the image forming apparatus 100. The memory 102 stores the rotation cycle for each linear velocity of the fixing device shown in FIG. A drive source 103 configured by a motor or the like is also connected to the control unit 101, and the drive source 103 rotationally drives the pressure roller 4 (pressure member) in the fixing device 1. The fixing belt 2 (fixing member) forming a nip with the pressure roller 4 is rotated together.

  A heater 3 which is a heating source of the fixing device and a temperature sensor 31 which is a temperature detecting means for detecting the temperature of the fixing member (fixing belt 2) are also connected to the control unit 101, and the temperature of the fixing belt 2 is detected by the temperature sensor 31. Is detected and the heater 3 is controlled.

  The conduction detecting means 104 is provided inside the fixing unit (fixing device) such as the above-mentioned electrodes (61, 62, 63, 64) in the vicinity of the holding member 5, but the voltage applied to the electrodes is supplied from the main body side. There is. The fixing device can be downsized by adopting a configuration in which the voltage applied to the electrodes is supplied from the main body side. The voltage itself applied to the electrodes is about 5 V DC, and there is no concern that the toner during fixing will be electrically scattered.

  FIG. 6 is a timing chart showing the detection cycle for each linear velocity set in the image forming apparatus of the present embodiment, and FIG. 6A shows the rotation cycle of the fixing member during driving at the linear velocity: V. There is. Further, (b) shows the rotation cycle of the fixing member when driven at a linear velocity of 1/2 V.

  Normally, the image forming apparatus has several transport linear velocity zones depending on the paper thickness and the image pattern in order to improve the image quality. If the rotation detection cycle is stored in the memory 102 in accordance with each linear velocity band, the rotation can be detected in each linear velocity band. A simple method for the rotation / non-rotation determination is a condition such as "how many times the signal voltage is counted in a predetermined time (predetermined time) to make the normal rotation". When the fusing device warms up from around room temperature, the fusing belt may slip a little at the start of driving due to the particularly large starting torque, but this phenomenon is not an abnormality, so allow some margin for counting. Is also good.

If the number of counts has not reached (less than a predetermined number of counts), the control unit 101 determines that it is “abnormal” and stops energizing the heater 3 and driving the drive source 103 at a certain timing.
In this way, when "it is not determined that the rotation is normal", by stopping each supply (power supply) to the fixing device, it is possible to provide a safe fixing device that does not cause runaway.

Next, the configuration of the image forming apparatus according to the embodiment of the present invention will be described with reference to FIG.
The image forming apparatus 100 shown in FIG. 7 is a tandem-type color printer in which image forming units that form a plurality of color images are juxtaposed in the belt extending direction. However, the present invention is not limited to this method, and can be applied not only to a printer but also to a copying machine, a facsimile machine, or a multifunction machine having a plurality of functions.

  The image forming apparatus 100 includes photosensitive drums 20Y, 20C, 20M, and 20Bk as image carriers that can form images as images corresponding to the colors separated into yellow, cyan, magenta, and black. The tandem structure is adopted.

  In the image forming apparatus 100, the visible image formed on each of the photoconductor drums 20Y, 20C, 20M, and 20Bk is an endless belt that is an endless belt that can move in the direction of arrow A1 while facing the photoconductor drums (hereinafter referred to as an intermediate transfer member). , Which is referred to as a transfer belt). By executing the primary transfer process, the images of respective colors are superimposed and transferred, and then the secondary transfer process is performed on the recording sheet S on which a recording sheet or the like is used, so that the images are collectively transferred.

  Around the respective photosensitive drums, a device for performing image forming processing according to the rotation of the photosensitive drums is arranged. The photoconductor drum 20Bk that forms a black image will be described as a representative example. A charging device 30Bk, a developing device 40Bk, a primary transfer roller 12Bk, and a cleaning device 50Bk that perform image forming processing are arranged along the rotation direction of the photoconductor drum 20Bk. ing. The optical writing device 60 is used for writing using the writing light Lb performed after charging.

  In the superimposed transfer onto the transfer belt 11, the visible image formed on each of the photoconductor drums 20Y, 20C, 20M, and 20Bk is transferred onto the transfer belt 11 at the same position in the process of the transfer belt 11 moving in the A1 direction. To be done. For this reason, the transfer is performed in the A1 direction by applying a voltage by the primary transfer rollers 12Y, 12C, 12M, and 12Bk which are arranged to face the photoconductor drums 20Y, 20C, 20M, and 20Bk with the transfer belt 11 interposed therebetween. The timing is shifted from the upstream side to the downstream side.

  The photoconductor drums 20Y, 20C, 20M, and 20Bk are arranged in this order from the upstream side in the A1 direction. The photoconductor drums 20Y, 20C, 20M, and 20Bk are provided in image stations for forming yellow, cyan, magenta, and black images, respectively.

  The image forming apparatus 100 is arranged so as to face four image stations that perform image forming processing for each color and above the respective photoconductor drums 20Y, 20C, 20M, and 20Bk, and the transfer belt 11 and the primary transfer roller 12Y. , 12C, 12M, and 12Bk, a secondary transfer roller 14 that is disposed so as to face the transfer belt 11, is driven by the transfer belt 11, and rotates together with the transfer belt 11, and is disposed so as to face the transfer belt 11. It has a belt cleaning device 13 provided for cleaning the transfer belt 11, and an optical writing device 60 arranged below these four image stations so as to face each other.

  The optical writing device 60 is equipped with a semiconductor laser as a light source, a coupling lens, an fθ lens, a toroidal lens, a folding mirror, and a rotating polygon mirror as a polarizing means. The optical writing device 60 emits writing light Lb corresponding to each color to each of the photoconductor drums 20Y, 20C, 20M, and 20Bk to form an electrostatic latent image on the photoconductor drums 20Y, 20C, 20M, and 20Bk. It is configured as follows. In FIG. 7, the writing light Lb is labeled only for the image stations of the black image for the sake of convenience, but the same applies to the other image stations.

  The image forming apparatus 100 is provided with a sheet feeding device 70 as a paper feeding cassette loaded with recording sheets S conveyed between the photoconductor drums 20Y, 20C, 20M and 20Bk and the transfer belt 11. There is. Further, the recording sheet S conveyed from the sheet feeding device 70 is directed to the transfer portion between each photoconductor drum and the transfer belt 11 at a predetermined timing matched with the timing of forming the toner image by the image station. A pair of registration rollers 81 for feeding out is provided. Further, a sensor for detecting that the leading edge of the recording paper S has reached the registration roller pair 81 is provided.

  Further, in the image forming apparatus 100, the fixing device 1 as a fixing unit of a roller fixing system for fixing the toner image on the recording sheet S to which the toner image is transferred, and the recording sheet S on which the toner image is fixed are formed on the image forming apparatus 100. A discharge roller 82 is provided for discharging outside the main body. Further, at the upper part of the main body of the image forming apparatus 100, there is provided a paper discharge tray 83 for stacking the recording paper S discharged to the outside of the main body of the image forming apparatus 100 by the discharge roller 82. Further, below the discharge tray 83, toner bottles 9Y, 9C, 9M, and 9Bk filled with toners of yellow, cyan, magenta, and black are provided.

  The transfer belt unit 10 includes a transfer belt 11, primary transfer rollers 12Y, 12C, 12M, and 12Bk, as well as a driving roller 15 and a driven roller 16 around which the transfer belt 11 is wound.

  The driven roller 16 also has a function as a tension urging unit for the transfer belt 11. Therefore, the driven roller 16 is provided with an urging unit using a spring or the like. The transfer belt unit 10, the primary transfer rollers 12Y, 12C, 12M, and 12Bk, the secondary transfer roller 14, and the cleaning device 13 constitute a transfer device 10A.

  The sheet feeding device 70 is disposed below the main body of the image forming apparatus 100, and has a feeding roller 84 that comes into contact with the upper surface of the uppermost recording sheet S. By rotating the feeding roller 84 counterclockwise in the figure, the uppermost recording sheet S is fed toward the registration roller pair 81.

  Although not shown in detail, the cleaning device 13 provided in the transfer device 10A has a cleaning brush and a cleaning blade that are arranged so as to face and abut the transfer belt 11. The cleaning device 13 cleans the transfer belt 11 by scraping and removing foreign matter such as residual toner on the transfer belt 11 with a cleaning brush and a cleaning blade. The cleaning device 13 also has a discharging means for carrying out and discarding the residual toner removed from the transfer belt 11.

  As described above, in the fixing device and the image forming apparatus of the present invention, the conductive area provided on the fixing member, the conduction detecting means for detecting conduction in the conductive area, and the conduction detecting means By including a control unit to which the detection signal of is input, the rotation of the fixing member is detected without compromising the original function of fixing property, reducing the risk of member damage, and increasing the size and complexity. Therefore, it is possible to provide a fixing device and an image forming apparatus that are safe, inexpensive, and excellent in controllability.

  Further, the conduction detecting unit has a plurality of electrodes, and when the plurality of electrodes simultaneously contact the conductive region, the conduction is conducted in the conductive region, so that the rotation of the fixing member can be reliably detected with a simple configuration. In addition, it is possible to make a reliable rotation determination even during continuous sheet passing.

  Further, by the configuration in which the continuity detecting unit is arranged on the holding member that holds the fixing member, it is possible to detect the rotation of the fixing member without causing an increase in size and complexity around the fixing device. Further, the present invention can be applied to a fixing device having a halogen heater or the like, which is relatively inexpensive and has excellent controllability, as a heat source, and the rotation of the fixing member can be detected even in that configuration.

  Further, the fixing member has a non-conductive inner surface sliding layer, a metal base material layer, an elastic layer and a surface release layer, and a part of the inner surface sliding layer is removed to expose the metal base material layer to form a conductive area. In this configuration, the inner sliding layer functions as a non-conductive area, the base material exposed layer functions as a conductive area, and it is not necessary to separately provide a conductive area on the surface layer of the fixing member, so that an increase in cost can be suppressed. Further, since it is not necessary to provide holes in the elastic layer or the base material layer, problems such as damage can be suppressed.

Further, since the continuity detecting means is arranged on one side in the fixing member axial direction, the continuity detecting means can be provided on only one side, and the fixing device is not made large and complicated.
Further, conductive regions where a part of the inner sliding layer is removed to expose the metal base layer are provided on both sides in the axial direction of the fixing member, and a conduction detecting unit is arranged to detect each conductive region. With this configuration, various configurations can be supported, and the degree of freedom in design increases.

  Further, since the fixing member is driven to rotate together with the pressing member, it is possible to detect the rotation of the fixing member corresponding to such an apparatus configuration.

The present invention has been described above based on the illustrated example, but the present invention is not limited to this. For example, the heat source of the fixing device is not limited to the halogen heater, and any heat source to which the present invention can be applied can be adopted.
The shape and size of the conductive region, the position where the conductive region is arranged, and the like can be appropriately set.
The configuration of the continuity detecting means is also an example of the embodiment and is not limited to this, and an appropriate configuration can be adopted as long as the continuity can be detected.

The present invention is not limited to the belt fixing device of the embodiment, but can be applied to a heat roll type using a rigid fixing roller.
The image forming apparatus is not limited to a printer, but may be a copying machine, a facsimile, or a multi-function peripheral having a plurality of functions. Further, the configuration of the image forming unit is not limited to the tandem system, and an arbitrary configuration can be adopted. Not only a full-color machine, but also a multi-color machine or a monochrome device may be used.

1 fixing device 2 fixing belt (fixing member)
3 Fixing heater (heating source)
4 Pressure roller (pressure member)
9A, 9B Holding members 21, 22 Conductive areas 61, 62 Electrodes 63, 64 Electrodes 100 Image forming apparatus 101 Control unit 102 Memory 103 Drive source 104 Continuity detection means S Paper (recording medium, recording material)
N fixing nip

JP, 2013-133750, A

Claims (8)

A recording material that includes a rotatable fixing member, a pressure member that is pressed against the fixing member to form a nip portion, and a heating source that heats the fixing member, and that holds the unfixed toner image in the nip portion. In a fixing device that passes and fixes an unfixed toner image on a recording material,
A conductive region provided on the fixing member,
Continuity detection means for detecting conduction in the conductive region,
And a control unit to which a detection signal from the continuity detection unit is input.   The fixing device according to claim 1, wherein the conduction detecting unit has a plurality of electrodes, and when the plurality of electrodes simultaneously come into contact with the conductive region, the conduction is performed in the conductive region. A holding member that is arranged at each of both end portions in the axial direction of the fixing member and holds the fixing member,
The fixing device according to claim 1, wherein the continuity detecting unit is arranged on the holding member. The fixing member has a non-conductive inner sliding layer, a metal base layer, an elastic layer and a surface release layer,
The fixing device according to claim 1, wherein a part of the inner sliding layer is removed to expose the metal base layer to form the conductive region. The fixing device according to any one of claims 1 to 4, wherein the conduction detecting unit is arranged on one side in the axial direction of the fixing member.   Conductive regions in which a part of the inner sliding layer is removed to expose the metal base layer are provided on both sides in the axial direction of the fixing member, and the conduction detecting unit detects the conductive regions. The fixing device according to claim 1, wherein the fixing device is arranged.   The fixing device according to claim 1, wherein the fixing member is driven together with the pressing member. An image forming apparatus comprising the fixing device according to claim 1.

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