JP2009251132A - Fixing apparatus and image forming apparatus provided with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing apparatus which attains a uniform fixing ability by making the temperature distribution on a fixing roller surface uniform by uniforming a heat generated amount distribution by preventing the occurrence of variance in electric resistance value in the flowing direction of current in a heat generating layer in the heat generating layer composed of a sheet heating element formed on a roller surface. <P>SOLUTION: The heat generating layer 53 for generating heat by having current supplied is composed of the sheet heating element provided with a positive resistance temperature characteristic and formed on the surface of the fixing roller 41. In the heat generating layer 53, a set of electrodes 59 are formed in parallel to the axial direction of the fixing roller 41 so that the flowing direction of the current which flows to the heat generating layer 53 is in the direction which is approximately orthogonal to the axial direction of the fixing roller 41. Furthermore, the region with the smaller area among the two regions which are in between the set of electrodes 59 is an electrode insulation section 50 in the heat generating layer 53. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fixing device that fixes a toner image on a recording medium by heat and pressure, and an image forming apparatus including the fixing device.

  An electrophotographic recording system is widely used in image forming apparatuses such as copying machines and facsimile machines. In an electrophotographic image forming apparatus, a latent image formed on an image carrier is developed with toner as a developer to form a toner image, and the toner image is electrostatically transferred to a recording medium. The toner image transferred onto the recording medium is fixed on a recording medium by applying heat and pressure by a fixing device.

  Patent Document 1 discloses a heat roller in which a planar heating element having PTC (Positive Temperature Coefficient) characteristics is formed on the surface. In the heat roller disclosed in Patent Document 1, a plurality of electrodes are provided on the peripheral surface of the heat roller and connected to the sheet heating element, and the sheet heating element is heated by current flowing between the electrodes. It generates energy and generates heat, so that the temperature of the heat roller surface can be raised. Such a heat roller can be applied to a heat fixing roller of a fixing device provided in the image forming apparatus.

JP-A-60-131784

  In the heat roller disclosed in Patent Document 1, a plurality of electrodes are provided on the peripheral surface of the heat roller, and a current flows between the plurality of electrodes. A plurality of regions) can be formed in the direction of current flow.

  When a plurality of heat generating regions can be formed in the direction of current flow in a planar heating element, the electrical resistance value in each heating region depends on the electrode arrangement interval, the thickness variation of the heating layer of the planar heating element in each heating region, etc. May not be exactly the same. Therefore, a large amount of current flows in a region having a low electrical resistance value in each heat generating region, and the amount of heat generation is relatively increased. In this way, the heat generation amount distribution in the direction of current flow on the surface of the sheet heating element becomes non-uniform, and the temperature distribution in the direction of current flow on the surface of the heat roller becomes non-uniform.

  When such a heat roller is applied to the heat fixing roller of the fixing device and the temperature distribution on the roller surface becomes non-uniform, uniform fixing ability cannot be achieved. For this reason, in the fixed image formed on the recording medium, uneven gloss and variation in fixing strength occur, and the quality of the fixed image is deteriorated.

  Accordingly, an object of the present invention is to prevent the occurrence of variation in the electric resistance value in the current flow direction of the heat generation layer in the heat generation layer formed of a planar heating element formed on the roller surface, and to make the heat generation amount distribution uniform. It is possible to provide a fixing device that can achieve a uniform fixing ability by making the temperature distribution on the surface of the fixing roller uniform. Another object of the present invention is to provide an image forming apparatus provided with such a fixing device.

The present invention includes a fixing roller and a pressure roller facing the fixing roller, and a toner image carried on the recording medium is recorded on the recording medium in a fixing nip formed by the fixing roller and the pressure roller. A fixing device for fixing by heating and pressing,
The fixing roller surface is formed of a planar heating element having a positive resistance temperature characteristic, and a heating layer is formed that generates heat when current is supplied,
In the heat generating layer, a pair of electrode portions are formed in parallel to the axial direction of the fixing roller so that the flow direction of the current flowing through the heat generating layer is substantially perpendicular to the axial direction of the fixing roller.
In the heat generating layer, the smaller region of the two regions sandwiched between the pair of electrode portions is an electrode insulating portion that does not flow current.

  In the invention, it is preferable that the electrode insulating portion is formed such that an area ratio of the electrode insulating portion to an area of the heat generating layer is 0.1% or more and 3% or less.

  In the present invention, the fixing roller is characterized in that the heat generating layer is formed on an outer peripheral surface of a roller base material, and a release layer capable of preventing toner adhesion is formed on the outermost layer.

The present invention also includes a temperature detection means for detecting the temperature of the surface of the fixing roller,
Temperature control means for controlling the power supplied to the heat generating layer so that the surface temperature of the fixing roller becomes a predetermined temperature based on temperature data detected by the temperature detection means. .

In the present invention, a contact portion to which a voltage for supplying power to the heat generating layer is applied is provided to face the surface of the fixing roller.
At both ends in the width direction of the heat generating layer, a power receiving portion that receives a current flowing by a voltage applied to the contact portion and supplies the current to the electrode portion is formed over the entire circumferential direction,
The power reception unit is configured to receive power by sliding on the contact portion when the fixing roller rotates around an axis.

The present invention also includes an endless fixing belt stretched between a fixing roller and a heat generating support roller, and a pressure roller facing the fixing roller via the fixing belt, the heat generating support roller being The fixing belt is heated in contact with the fixing belt, and a toner image carried on the recording medium is heated and pressed on the recording medium at a fixing nip portion formed by the fixing belt and the pressure roller. A fixing device that
The surface of the heat generation support roller is formed of a sheet heating element having a positive resistance temperature characteristic, and a heat generation layer that generates heat when an electric current is supplied is formed.
In the heat generating layer, a pair of electrode portions are formed in parallel with the axial direction of the heat generating support roller so that the flow direction of the current flowing through the heat generating layer is substantially orthogonal to the axial direction of the fixing roller.
In the heat generating layer, the smaller region of the two regions sandwiched between the pair of electrode portions is an electrode insulating portion that does not flow current.

  According to the present invention, the heat generating support roller has the heat generating layer formed on an outer peripheral surface of the support roller base material, and a protective layer capable of reducing a frictional force between the fixing belt and the outermost layer. It is characterized by.

The present invention also includes a temperature detection means for detecting the temperature of the surface of the fixing belt,
Temperature control means for controlling the power supplied to the heat generating layer so that the surface temperature of the fixing belt becomes a predetermined temperature based on the temperature data detected by the temperature detection means. .

Further, in the present invention, a contact portion to which a voltage for supplying power to the heat generating layer is applied is provided facing the surface of the heat generating support roller,
At both ends in the width direction of the heat generating layer, a power receiving portion that receives a current flowing by a voltage applied to the contact portion and supplies the current to the electrode portion is formed over the entire circumferential direction,
The power reception unit is configured to receive power by sliding on the contact portion when the heat generating support roller rotates around an axis.

In the invention, it is preferable that the length of the heat generating layer in the width direction is set longer than the maximum width of the recording medium passing through the fixing nip portion.
According to another aspect of the present invention, there is provided an image forming apparatus including the fixing device.

  According to the present invention, the heating roller surface is formed of a sheet heating element having a positive resistance temperature characteristic and generates heat when current is supplied. In the heat generating layer, a pair of electrode portions are formed in parallel with the axial direction of the fixing roller so that the flow direction of the current flowing through the heat generating layer is substantially perpendicular to the axial direction of the fixing roller. Furthermore, in the heat generating layer, an electrode insulating portion that does not flow current is formed in the smaller region of the two regions sandwiched between the pair of electrode portions.

  For example, in the heat generation layer, when current flows in each of two regions sandwiched between a pair of electrode portions and two heat generation regions are formed, the arrangement interval of the electrodes and the heat generation layer in each heat generation region The electric resistance value in each heat generating region may not be completely the same due to the thickness variation of the heat resistance. Therefore, a large amount of current flows in a region having a low electrical resistance value in each heat generating region, and the amount of heat generation is relatively increased. In this way, the heat generation amount distribution in the current flow direction of the heat generation layer becomes non-uniform.

  On the other hand, the heat generating layer is an electrode insulating part in which the smaller area of the two areas sandwiched between a pair of electrode parts does not flow current. Can be defined in one area. Therefore, it is possible to prevent the electric resistance value variation in the current flow direction from occurring in one region having the larger area, and to make the heat generation amount distribution uniform. As a result, the temperature distribution in the direction of current flow can be made uniform on the surface of the fixing roller corresponding to the heat generation area which is one of the larger areas in the heat generation layer, and a uniform fixing ability in the fixing nip portion can be achieved. Become. Accordingly, it is possible to obtain a uniform and high-quality fixed image without gloss unevenness and fixing strength variation.

  According to the invention, the electrode insulating part is formed such that the area ratio of the electrode insulating part to the area of the heat generating layer is 0.1% or more and 3% or less. As a result, sufficient insulation can be ensured in the electrode insulating portion, and the area of the heat generating region in the heat generating layer can be prevented from becoming too small, and the heat generated in the heat generating region can be conducted to the entire surface of the fixing roller. A uniform temperature distribution on the surface of the fixing roller can be maintained.

  According to the invention, the fixing roller has a heat generating layer formed on the outer peripheral surface of the roller base material, and a release layer capable of preventing toner adhesion is formed on the outermost layer. Since the heat generating layer is formed on the outer peripheral surface of the roller base material, the heat conduction distance from the heat generating layer to the fixing surface in contact with the recording medium is shortened. Therefore, the temperature controllability on the surface of the fixing roller due to the heat generated by the heat generating layer is improved, and the temperature on the surface of the fixing roller can be controlled with higher accuracy. In addition, since the release layer is formed on the outermost layer serving as the fixing surface of the fixing roller, it is possible to prevent the toner carried on the recording medium from adhering to the surface of the fixing roller.

  According to the invention, the temperature detecting means detects the temperature of the surface of the fixing roller. The temperature control unit controls the power supply to the heat generating layer based on the detected temperature data so that the surface temperature of the fixing roller becomes a predetermined temperature. Therefore, it can be directly controlled with high accuracy so that the temperature of the surface of the fixing roller forming the fixing nip portion through which the recording medium passes becomes a predetermined temperature.

  Further, according to the present invention, the contact portion to which a voltage for supplying power to the heat generating layer is applied is provided so as to face the surface of the fixing roller. And the power receiving part which receives the electric current which flows with the voltage applied to the contact part and supplies it to an electrode part is formed in the width direction both ends of the heat generating layer over the whole circumferential direction. The power receiving unit is configured to slide on the contact unit to receive power when the fixing roller rotates around the axis. For this reason, even when the fixing roller rotates around the axis, power can be stably supplied from the contact portion to the power receiving portion.

  According to the invention, the fixing device is carried on the recording medium at the fixing nip portion formed by the fixing belt and the pressure roller, with the heat generating support roller contacting the fixing belt to heat the fixing belt. The toner image is fixed by heating and pressing on the recording medium. In such a fixing device, on the surface of the heat generating support roller, a heat generating layer that is made of a planar heat generating element having a positive resistance temperature characteristic and generates heat when current is supplied is formed. In the heat generating layer, a pair of electrode portions are formed in parallel with the axial direction of the heat generating support roller so that the flow direction of the current flowing through the heat generating layer is substantially perpendicular to the axial direction of the heat generating support roller. . Further, in the heat generating layer, the smaller region of the two regions sandwiched between the pair of electrode portions is an electrode insulating portion that does not flow current.

  In the heat generation layer, one of the two regions sandwiched between a pair of electrode portions, one region having a larger area where current flows only in a region on the side where the electrode insulating portion is not formed and heat is generated. Stipulated in Therefore, it is possible to prevent the electric resistance value variation in the current flow direction from occurring in one region having the larger area, and to make the heat generation amount distribution uniform. Therefore, the temperature distribution in the direction of current flow can be made uniform on the surface of the heat generation support roller corresponding to the heat generation region of the heat generation layer. As a result, the heat generating support roller can heat the fixing belt so that the temperature distribution on the surface of the fixing belt becomes uniform. Accordingly, it is possible to achieve a uniform fixing ability at the fixing nip portion formed by the fixing belt and the pressure roller.

  According to the invention, the heat generating support roller has a heat generating layer formed on the outer peripheral surface of the support roller base material, and a protective layer capable of reducing the frictional force with the fixing belt is formed on the outermost layer. Since the heat generating layer is formed on the outer peripheral surface of the support roller base material, the heat conduction distance from the heat generating layer to the fixing belt is shortened. Therefore, the temperature controllability of the fixing belt surface due to the heat generation of the heat generating layer is improved, and the temperature of the fixing belt surface can be controlled with higher accuracy. In addition, a protective layer is formed on the outermost layer of the heat generating support roller that comes into contact with the fixing belt, so that even if the fixing belt slides in contact with the heat generating support roller, the surface of the heat generating support roller is worn. Can be prevented. Therefore, the heat generating layer formed on the surface of the heat generating support roller can stably generate heat uniformly over a long period of time.

  According to the invention, the temperature detecting means detects the temperature of the surface of the fixing belt. The temperature control unit controls the power supply to the heat generating layer so that the surface temperature of the fixing belt becomes a predetermined temperature based on the detected temperature data. Therefore, it can be directly controlled with high accuracy so that the temperature of the surface of the fixing belt forming the fixing nip portion through which the recording medium passes becomes a predetermined temperature.

  According to the invention, the contact portion to which a voltage for supplying power to the heat generating layer is applied is provided to face the surface of the heat generating support roller. And the power receiving part which receives the electric current which flows with the voltage applied to the contact part and supplies it to an electrode part is formed in the width direction both ends of the heat generating layer over the whole circumferential direction. The power reception unit is configured to slide on the contact portion to receive power when the heat generation support roller rotates about the axis. Therefore, even when the heat generating support roller rotates around the axis, power can be stably supplied from the contact portion to the power receiving portion.

  According to the invention, the length of the heat generating layer in the width direction is set to be longer than the maximum width of the recording medium passing through the fixing nip portion. Accordingly, the heat generating layer generates heat uniformly in a region corresponding to the width range through which the recording medium passes, and the temperature distribution in the width range of the fixing nip portion can be made uniform.

  According to the invention, an image forming apparatus includes the fixing device that can make the temperature distribution on the fixing surface uniform. Therefore, it is possible to form a uniform and high-quality image without uneven gloss and uneven fixing strength.

  FIG. 1 is a diagram illustrating a configuration of an image forming apparatus 100 according to an embodiment of the present invention. The image forming apparatus 100 is an apparatus that forms multi-color and single-color images on a recording sheet 1 that is a recording medium based on image data of a read original or image data transmitted via a network or the like. The image forming apparatus 100 includes a visible image forming unit 10, a paper feed tray 20, a recording paper transport unit 30, and a fixing device 40. The image forming apparatus 100 corresponds to the hues of four colors of cyan (C), magenta (M), and yellow (Y), which are three subtractive primary colors obtained by color separation of black (K) and a color image. Using the image data, image formation is performed in the visible image forming units 10Y, 10M, 10C, and 10K corresponding to the respective hues. The visible image forming units 10Y, 10M, 10C, and 10K corresponding to four hues are so-called tandem type image forming apparatuses arranged in a line along a conveyance path through which the recording paper 1 is conveyed.

  The recording paper conveying means 30 has an endless conveying belt 33 that is stretched by a pair of drive rollers 31 and an idling roller 32 and that is controlled by a predetermined peripheral speed and rotates in the rotation direction B. The recording paper 1 supplied from 20 is electrostatically attracted to the transport belt 33 and transported in the transport direction A, which is the direction toward the visible image forming unit 10.

  The visible image forming unit 10 forms an image on the recording paper 1 conveyed by the recording paper conveying means 30. Four members are provided in the visible image forming unit 10 to correspond to the hues of black (K), cyan (C), magenta (M), and yellow (Y). The visible image forming unit 10 includes a photosensitive drum 11, a charging roller 12, a laser beam irradiation unit 13, a developing device 14, a transfer roller 15, and a cleaner 16.

  The charging roller 12 is a contact-type charger that uniformly charges the surface of the photosensitive drum 11 to a predetermined potential. Instead of the charging roller 12, a contact type charger using a charging brush or a non-contact type charger using a charging wire may be used.

  The laser light irradiation means 13 applies a light beam such as a laser beam modulated by image data of each hue of black (K), cyan (C), magenta (M), and yellow (Y) to a corresponding photoconductor. The drum 11 is irradiated. The photosensitive drum 11 forms an electrostatic latent image based on image data of each hue of black (K), cyan (C), magenta (M), and yellow (Y).

  The developing device 14 supplies toner as a developer to the surface of the photosensitive drum 11 on which the electrostatic latent image is formed, and develops the electrostatic latent image into a toner image. Each of the developing devices 14 provided in each of the visible image forming units 10Y, 10M, 10C, and 10K stores toner of each hue of black (K), cyan (C), magenta (M), and yellow (Y). The electrostatic latent image of each hue formed on the photosensitive drum 11 is visualized as a toner image of each hue. The cleaner 16 removes and collects toner remaining on the surface of the photosensitive drum 11 after development and image transfer.

  The transfer roller 15 applies a bias voltage having a polarity opposite to that of the toner to the visualized toner image, and sequentially transfers the visualized toner image onto the recording paper 1 conveyed by the conveying unit 30. . The recording paper 1 to which the toner image has been transferred is peeled off from the transport belt 33 by the curvature of the drive roller 31 and then transported to the fixing device 40.

  FIG. 2 is a cross-sectional view showing the configuration of the fixing device 40 according to the first embodiment of the present invention. FIG. 3 is a cross-sectional view illustrating a configuration of a fixing roller 41 included in the fixing device 40. FIG. 4 is a developed view of the peripheral surface of the heat generating layer 53 formed on the fixing roller 41. The fixing device 40 includes a fixing roller 41 and a pressure roller 42. In the fixing device 40, the fixing roller 41 and the pressure roller 42 are pressed against each other with a predetermined load (about 300 N in the present embodiment), and the fixing nip portion (the fixing roller 41 and the pressure roller 42 is between them). Part that abuts each other).

  In the fixing device 40, the recording paper 1 passes through the fixing nip portion at a predetermined fixing speed (200 mm / sec in the present embodiment) and a copying speed (30 sheets / min in the case of A4 size paper lateral feed in the present embodiment). In this case, the toner image 1a carried on the recording paper 1 is heated and pressed on the recording paper 1 for fixing. When the recording paper 1 passes through the fixing nip portion, the fixing roller 41 contacts the toner image forming surface of the recording paper 1, while the pressure roller 42 contacts the surface opposite to the toner image forming surface of the recording paper 1. It is like that. The fixing speed is a so-called process speed, and the copying speed is the number of copies per minute. The toner image 1a formed on the recording paper 1 is an unfixed toner image, which is a non-magnetic one-component developer (non-magnetic toner), a non-magnetic two-component developer (non-magnetic toner and carrier), magnetic It is formed by a toner developer such as a developer (magnetic toner).

  The fixing roller 41 has a hollow roll shape, and forms a fixing nip portion by being pressed against the pressure roller 42. At the same time, the fixing roller 41 is rotationally driven around a rotation axis by a drive motor (not shown) while being supported by the bearing portion 58. By doing so, the recording paper 1 passing through the fixing nip portion is conveyed. As shown in FIG. 3, the fixing roller 41 has a laminated structure in which a roller metal core 51, a rubber layer 52, a heat generating layer 53, and a release layer 54 are formed in this order from the inside. As a method of laminating the rubber layer 52, the heat generating layer 53, and the release layer 54 on the roller metal core 51, a conventionally well-known method can be used. For example, a metal such as iron, stainless steel, aluminum, or copper, or an alloy thereof can be used for the roller core 51, but in this embodiment, the roller core 51 is made of iron and has a thickness of 0. .About 8 mm.

  The rubber layer 52 serves as an insulating layer and an elastic layer, and is made of a heat-resistant rubber material such as silicon rubber or fluorine rubber. In the present embodiment, the rubber layer 52 is a layer made of silicon rubber having a thickness of about 500 μm. The rubber layer 52 is formed between the roller cored bar 51 and the heat generating layer 53 and ensures insulation between them, so that the current supplied to the heat generating layer 53 is prevented from flowing to the roller cored bar 51. Can do. The rubber layer 52 also serves as an elastic layer. Since the fixing roller 41 has the rubber layer 52 as an elastic layer, the surface of the fixing roller 41 is elastically deformed corresponding to the unevenness of the toner image 1a on the recording paper 1 and contacts the toner image 1a so as to cover the toner image 1a. In particular, it is possible to satisfactorily fix a color toner image having a large amount of toner. A hard roller in which an insulating layer is formed on the roller metal core 51 without forming the rubber layer 52 on the surface of the fixing roller 41 may be used. Such a hard roller can be suitably used as a fixing roller for a monochrome single-color toner image with a small amount of toner on the recording paper 1.

  The heat generating layer 53 heats the surface of the fixing roller 41 (for example, heats the surface of the fixing roller 41 to 190 ° C.), and heats the recording paper 1 passing through the fixing nip portion. It is a layer that generates heat when supplied. Here, since the heat generating layer 53 is formed outside the roller cored bar 51, a heat conduction distance from the heat generating layer 53 to a later-described release layer 54 which is a fixing surface in contact with the recording paper 1 is shortened. . Therefore, the temperature controllability of the surface of the fixing roller 41 due to the heat generation of the heat generating layer 53 is improved, and the temperature of the surface of the fixing roller 41 can be controlled with higher accuracy.

  Further, the heat generating layer 53 may be formed so as to be laminated on the surface of the roller cored bar 51 as a layer inside the rubber layer 52. Accordingly, since the heat generating layer 53 is not deformed due to the deformation of the rubber layer 52, the durability of the heat generating layer 53 can be improved. In this case, in order to ensure insulation between the heat generating layer 53 and the roller metal core 51, a non-conductive member such as a ceramic insulator is disposed on the bearing portion 58.

  The heat generating layer 53 includes a heat generating part 53A, a power receiving insulating part 55, a power receiving part 57, an electrode part 59, and an electrode insulating part 50. Here, in the heat generating layer 53, a method well known in the art is used as a method of forming the heat generating portion 53A, the power receiving insulating portion 55, the power receiving portion 57, the electrode portion 59, and the electrode insulating portion 50. it can. The heat generating portion 53A is a portion that generates heat when supplied with current, and is formed of a material having positive resistance temperature characteristics (Positive Temperature Coefficient characteristics, abbreviated as PTC characteristics). Here, the PTC characteristic is a characteristic in which, when a temperature distribution is generated in the heat generating portion 53A, an electric resistance value of a portion having a high temperature becomes high.

  Further, the length in the width direction, which is the direction corresponding to the axial direction of the fixing roller 41 of the heat generating portion 53A, is set longer than the maximum width of the recording paper 1 passing through the fixing nip portion. Thus, the heat generating portion 53A generates heat uniformly in a region corresponding to the width range through which the recording paper 1 passes, and the temperature distribution in the width range through which the recording paper 1 on the surface of the fixing roller 41 passes can be made uniform. In the present embodiment, the width is set to 330 mm, which is longer than the width 298 mm of the A3 size recording paper 1. The layer thickness of the heat generating portion 53A is set to about 200 μm.

  Examples of the material constituting the heat generating portion 53A include semiconductor ceramics based on barium titanate. Materials having PTC characteristics based on barium titanate transition from semiconductive to insulating. That is, as the crystal structure undergoes a phase transition from the tetragonal system to the cubic system, the spontaneous polarization disappears, the domain disappears, and PTC characteristics are exhibited.

  Further, as a material constituting the heat generating portion 53A, a composite material in which a heat-resistant polymer of an organic material or an organic-inorganic composite is filled with a conductive filler can be exemplified. Examples of the heat resistant polymer include polyimide resin, polyphenylene oxide resin, polyphenylene sulfide resin, syndiotactic polystyrene resin, crystalline polyester resin, polyether ether ketone resin, epoxy resin, and silicon resin. Further, the PTC characteristic is realized by glass transition or crystal transition of the heat resistant polymer.

The heat generating portion 53A is preferably a material that has a large impedance and is easy to handle in terms of an electric circuit, and that is easy to form on the surface of the fixing roller 41 and is relatively inexpensive. Fill. Examples of the conductive filler include metal, carbon, oxide, carbide, and nitride particles, such as nickel, copper, tungsten, titanium, silver, gold, aluminum, activated carbon, graphite, graphite, tin oxide, indium oxide, and oxide. Examples thereof include conductive particles such as vanadium, rhenium oxide, silicon carbide, titanium nitride, TiB ₂ , ZrB ₂ , WSi ₂ , TiC, and TiO ₂ .

  The size of the conductive particles is preferably in the range of 0.1 to 100 μm. Particles of less than 0.1 μm are very fine and difficult to disperse uniformly. With particles exceeding 100 μm, it is difficult to uniformly disperse and it is difficult to adjust the electric resistance value. Moreover, it is preferable to contain electroconductive particle in the ratio of 10-70 volume%. If it is less than 10%, conductivity is not exhibited. On the other hand, if it exceeds 70%, it becomes difficult to include a heat-resistant polymer that is a sufficient base polymer between the particles, and the layer shape of the heat generating portion 53A cannot be maintained.

  Also, a curing agent can be added to improve the durability of the heat resistant polymer at high temperatures. These curing agents are selected according to the kind of heat-resistant polymer, and examples thereof include commonly used curing agents such as polyisocyanates, aliphatic or aromatic polyamines, thioureas, and acid anhydrides.

  The power receiving portion 57 included in the heat generating layer 53 is a portion that receives the current flowing by the voltage applied from the power supply 45 through the sliding contact portion 56, and is disposed on the outer sides of both ends in the width direction of the heat generating portion 53A. Formed over. The power receiving unit 57 includes a first power receiving unit 57a on one end side in the width direction of the heat generating unit 53A, and a second power receiving unit 57b on the other end side. The first power receiving unit 57a and the second power receiving unit 57b are made of a good conductor such as copper or aluminum. Here, a plurality of sliding contact portions 56 are provided in the circumferential direction of the fixing roller 41 so as to face the first power receiving portion 57a and the second power receiving portion 57b, and when the fixing roller 41 rotates around the axis. The power receiving units 57a and 57b slide to supply current flowing by the voltage applied from the power supply 45 to the power receiving units 57a and 57b. With such a configuration, even when the fixing roller 41 rotates around the axis, power can be stably supplied from the sliding contact portion 56 to the power receiving portions 57a and 57b.

  Furthermore, the heat generating layer 53 is provided with an electrode portion 59 that supplies current to the heat generating portion 53A based on the power reception by the power receiving portions 57a and 57b. As the electrode portion 59, a first electrode portion 59a extending in parallel with the width direction of the heat generating portion 53A from the first power receiving portion 57a toward the other end of the heat generating portion 53A is provided, and the second power receiving portion 57b. A second electrode portion 59b extending in parallel to the width direction of the heat generating portion 53A is provided toward the one end portion side of the heat generating portion 53A. The first electrode portion 59a and the second electrode portion 59b are made of a good conductor such as copper or aluminum. By forming the pair of electrode portions 59a and 59b in this way, the direction of the current flowing through the heat generating portion 53A is the direction C (the recording paper 1 is fixed) substantially perpendicular to the width direction of the heat generating portion 53A. The direction of conveyance through the nip portion).

  The energization of the heat generating portion 53A causes the heat generating portion 53A to generate heat and rise in temperature, and heats the surface of the fixing roller 41 by heat conduction. In the heat generating portion 53A, the electrical resistance value between the pair of electrode portions 59a and 59b is preferably set to 5 to 60Ω, and more preferably 8 to 45Ω so as to generate heat with a predetermined heat generation amount. In the present embodiment, in the heat generating portion 53A, the electrical resistance value between the pair of electrode portions 59a and 59b is set to 10Ω so that a heat generation amount of 1000 W is obtained at an applied voltage of 100V.

  Further, in the heat generating portion 53A, one of the two regions sandwiched between the first electrode portion 59a and the second electrode portion 59b has a heat resistant resin such as polyimide or fluororesin that does not pass current, An electrode insulating portion 50 made of an insulator such as a paste-like ceramic material applied and fired is formed. That is, in the heat generating portion 53A, a current flows only in a region on the side where the electrode insulating portion 50 is not formed, out of two regions sandwiched between the first electrode portion 59a and the second electrode portion 59b. The heat generation area to be performed is defined as one area.

  For example, when current flows in each of two regions sandwiched between a pair of electrode portions and two heat generation regions are formed, the arrangement interval of the electrodes and the thickness variation of the heat generation layer in each heat generation region For example, the electric resistance values in the heat generation regions may not be completely the same. Therefore, a large amount of current flows in a region having a low electrical resistance value in each heat generating region, and the amount of heat generation is relatively increased. In this way, the heat generation amount distribution in the direction of current flow in the heat generating portion becomes non-uniform.

  On the other hand, in the heat generating portion 53A, since the heat generating area is defined as one area, in the heat generating area of the heat generating portion 53A, it is possible to prevent the electric resistance value variation in the current flow direction from occurring and to generate the heat generation amount. The distribution can be made uniform. Therefore, the temperature distribution in the direction of current flow can be made uniform on the surface of the fixing roller 41 corresponding to the heat generating area of the heat generating portion 53A, and uniform fixing ability in the fixing nip portion can be achieved. Accordingly, it is possible to obtain a uniform and high-quality fixed image without gloss unevenness and fixing strength variation.

  Here, the first electrode part 59a and the second electrode part 59b are brought close to each other so that the electrode insulating part 50 is formed in the gap, and the area of the electrode insulating part 50 with respect to the area of the heat generating part 53A is a predetermined ratio. It is preferable to make it smaller. At this time, the area ratio of the electrode insulating part 50 to the area of the heat generating part 53A is preferably set to be 0.1 to 3%. When the area ratio is smaller than 0.1%, sufficient insulation in the electrode insulating portion 50 cannot be ensured. On the other hand, if the area ratio is larger than 3%, the area of the heat generating area in the heat generating portion 53A becomes too small, and it becomes difficult for the heat generated in the heat generating area to be transmitted to the entire surface of the fixing roller 41, and the fixing roller. The uniform temperature distribution on the surface 41 cannot be maintained.

  A first power receiving / insulating portion 55a is formed on the inner side of the first power receiving portion 57a in the width direction of the heat generating layer 53 over the entire circumferential direction, and between the first power receiving portion 57a and the second electrode portion 59b. Direct current does not flow. Further, a second power receiving and insulating portion 55b is formed on the inner side of the second power receiving portion 57b in the width direction of the heat generating layer 53 over the entire circumferential direction, and between the second power receiving portion 57b and the first electrode portion 59a. Direct current does not flow. The first power receiving / insulating portion 55a and the second power receiving / insulating portion 55b are made of an insulator such as a heat-resistant resin such as polyimide or fluororesin or a paste-like ceramic material applied and fired.

  The release layer 54 is the outermost layer in the fixing roller 41 and is a layer that contacts the pressure roller 42 to form a fixing nip portion. Therefore, it is necessary to form the release layer 54 from a material that can prevent the toner image 1a on the recording paper 1 passing through the fixing nip from adhering to the surface of the fixing roller 41. Further, the release layer 54 needs to have heat conductivity for heating the recording paper 1 by conducting the heat generated in the heat generating portion 53 </ b> A to the entire surface of the fixing roller 41. Examples of the material constituting the release layer 54 include fluorine resins such as PFA (a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether) and PTFE (polytetrafluoroethylene), and hybrid materials thereof. Can do.

  The pressure roller 42 is opposed to and pressed against the fixing roller 41, and is provided so as to be rotatable about the rotation axis. The pressure roller 42 rotates following the rotation of the fixing roller 41. The pressure roller 42 has a three-layer structure in which a core metal, an elastic layer, and a release layer are formed in that order from the inside. For the metal core, for example, a metal such as iron, stainless steel, aluminum, copper, or an alloy thereof is used. For the elastic layer, a rubber material having heat resistance such as silicon rubber and fluorine rubber is suitable, and for the release layer, PFA (copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether) or PTFE (polytetrafluoroethylene) is suitable. A fluororesin such as fluoroethylene) is suitable. A heater lamp for heating the pressure roller 42 is disposed inside the pressure roller 42. A control circuit (not shown) supplies (energizes) rated power (for example, 450 W) to a heater lamp from a power supply circuit (not shown), whereby the heater lamp emits light and infrared rays are emitted from the heater lamp. As a result, the inner peripheral surface of the pressure roller 42 is heated by absorbing infrared rays, and the entire pressure roller 42 is heated.

  In the fixing device 40, as a temperature detection means, a fixing roller side thermistor 43 is disposed on the peripheral surface of the fixing roller 41, and a pressure roller side thermistor 44 is disposed on the peripheral surface of the pressure roller 42, respectively. It is designed to detect the surface temperature. Based on the temperature data detected by the thermistors 43 and 44, a control circuit (not shown) as a temperature control means sets the surface temperature of the fixing roller 41 and the pressure roller 42 to a predetermined temperature. The power supply (energization) to the heat generating layer 53 and the heater lamp is controlled. At this time, the heat generation layer 53 of the fixing roller 41 and the heater lamp of the pressure roller 42 are independent energization circuits.

  In the fixing roller 41 of the fixing device 40 configured as described above, as described above, the electrode insulating portion 50 is provided in one region sandwiched between the pair of electrode portions 59a and 59b formed in the heat generating portion 53A. Therefore, the variation in the electric resistance value in the current flow direction can be prevented, the heat generation amount distribution can be made uniform, and the temperature distribution in the current flow direction can be made uniform.

  Next, the temperature distribution in the axial direction of the surface of the fixing roller 41 (direction orthogonal to the current flow direction) will be described. FIG. 5 is a diagram showing a heat generation amount distribution and a temperature distribution with respect to the axial direction of the surface of the fixing roller 41 before the sheet is passed. FIG. 6 is a diagram showing a temperature distribution, an electric resistance value distribution, and a calorific value distribution with respect to the axial direction of the surface of the fixing roller 41 during paper passing. FIG. 7 is a diagram schematically showing an energized state of the surface of the heat generating layer 53 during paper passing.

  Before the recording paper 1 passes through the fixing nip portion, the heat generating portion 53A of the fixing roller 41 generates heat uniformly in the width direction (direction corresponding to the axial direction of the fixing roller 41). Therefore, the heat generation amount distribution in the axial direction on the surface of the fixing roller 41 is uniform as shown in FIG. Therefore, the temperature distribution in the axial direction on the surface of the fixing roller 41 is also uniform as shown in FIG.

  When the recording paper 1 passes through the fixing nip portion, both ends of the recording paper 1 outside the sheet passing width region in the axial direction of the surface of the fixing roller 41 are not deprived of heat by the recording paper 1. To rise. At this time, the paper passing width area of the recording paper 1 is larger for the large size paper than for the small size paper. Therefore, the temperature rise area width at both ends in the axial direction of the surface of the fixing roller 41 is large paper passing. Time becomes smaller.

  When the recording paper 1 passes through the fixing nip portion and a temperature distribution is generated in the axial direction of the surface of the fixing roller 41, the heat generating portion 53A formed of a material having PTC characteristics has a high temperature area on the surface of the fixing roller 41. Corresponding to the region portion where the electric resistance value is high (high electric resistance portion) is formed at both ends in the width direction, and the region portion where the electric resistance value is relatively low (low electric resistance portion) is the width direction. Formed in the center.

  At this time, since the current flow direction in the heat generating portion 53A is a direction orthogonal to the width direction, in the heat generating portion 53A, as shown in FIG. 7A, the high electric resistance portion and the low electric resistance portion are in parallel. It can be energized as a connection circuit. In this state, the voltage having the same voltage value is applied to the high electrical resistance portion and the low electrical resistance portion. For this reason, when the temperature control unit controls energization to the heat generating portion 53A based on the temperature data detected by the fixing roller side thermistor 43 provided on the peripheral surface of the fixing roller 41, the heat generation amount in the heat generating portion 53A is high. The electric resistance portion is lower than the low electric resistance portion. Here, in the present embodiment, the fixing roller side thermistor 43 is provided within the range of the sheet passing width on the peripheral surface of the fixing roller 41. As a result, the temperature control unit can control the energization to the heat generating portion 53A based on the temperature data detected by the fixing roller side thermistor 43 in the sheet passing width range of the recording paper 1. Therefore, the temperature in the sheet passing width range can be controlled. It can be directly controlled with high accuracy.

  In this way, the amount of heat generated by the high electrical resistance portion of the heat generating portion 53A is reduced, so that the temperature at both ends in the axial direction, which is a region corresponding to the high electrical resistance portion on the surface of the fixing roller 41, is high. . Therefore, the temperature distribution in the axial direction on the surface of the fixing roller 41 can be made uniform. Accordingly, in order to suppress temperature unevenness on the surface of the fixing roller 41 even when small-size paper having a large temperature rise area width at both ends in the axial direction on the surface of the fixing roller 41 is continuously passed, There is no need to reduce the paper throughput, and uniform high-quality images can be obtained with a higher throughput.

  On the other hand, when the recording paper passes through the fixing nip and a temperature distribution is generated in the axial direction of the surface of the fixing roller, and a high electric resistance portion and a low electric resistance portion are formed in the heat generation portion, the current flow in the heat generation portion When the direction is parallel to the width direction, as shown in FIG. 7B, the high electrical resistance portion and the low electrical resistance portion are energized as a series connection circuit. In such a case, an equal current flows through the high electrical resistance portion and the low electrical resistance portion, and more power is consumed in the high electrical resistance portion. For this reason, the temperature at both ends in the axial direction, which is a region corresponding to the high electrical resistance portion, on the surface of the fixing roller 41 further increases, and the temperature unevenness becomes more remarkable. This temperature unevenness may exceed the heat resistance temperature of the constituent members of the fixing device. Alternatively, it is necessary to greatly reduce the throughput of small size paper in order to suppress the temperature rise at both ends in the axial direction of the fixing roller.

  FIG. 8 is a cross-sectional view showing a configuration of a fixing device 60 according to the second embodiment of the present invention. FIG. 9 is a cross-sectional view illustrating a configuration of the heat generation support roller 62 included in the fixing device 60. The fixing device 60 according to the second embodiment is similar to the fixing device 40 according to the first embodiment, and corresponding portions are denoted by the same reference numerals and description thereof is omitted.

  The fixing device 60 includes a fixing roller 61, a pressure roller 42, a heat generation support roller 62, and a fixing belt 63. In the fixing device 60, the fixing belt 63 is stretched between the fixing roller 61 and the heat generation support roller 62, and the pressure roller 42 is disposed so as to face the fixing roller 61 through the fixing belt 63. That is, in the fixing device 60, the fixing nip portion is formed by the fixing belt 63 and the pressure roller 42. The axial directions of the fixing roller 61, the pressure roller 42, and the heat generation support roller 62 are parallel to each other.

  In the fixing device 60, the heat generating support roller 62 contacts the fixing belt 63 to heat the fixing belt 63, and the fixing roller 61 is heated by heat conduction from the fixing belt 63. The fixing roller 61 included in the fixing device 60 is the same as the fixing roller 41 included in the fixing device 40 except that a heat generating layer is not formed on the surface thereof.

  The fixing belt 63 is heated to a predetermined temperature by the heat generation support roller 62 and heats the recording paper 1 passing through the fixing nip portion. The fixing belt 63 is an endless belt, is suspended by a heating support roller 62 and a fixing roller 61, and is wound around the fixing roller 61 at a predetermined angle. The fixing belt 63 is driven to rotate following the fixing roller 61 when the fixing roller 61 rotates. The fixing belt 63 has an elastic layer made of an elastomer material (for example, silicon rubber) excellent in heat resistance and elasticity on the surface of a hollow cylindrical base material 63a made of a heat resistant resin such as polyimide or a metal material such as stainless steel or nickel. 63b is formed, and the surface thereof has a three-layer structure in which a release layer 63c made of a synthetic resin material (for example, a fluororesin such as PFA or PTFE) having excellent heat resistance and release properties is formed. Further, as the base material 63a, a fluororesin may be internally added to polyimide. Thereby, the sliding load with the heat generating support roller 62 can be reduced.

  The heat generation support roller 62 is provided so as to be rotatable about an axis, and rotates following the rotation of the fixing roller 61. The heat generating support roller 62 has a hollow roll shape, and has a laminated structure in which a roller core 71, a heat generating layer 53, and a protective layer 74 are formed in this order from the inside. The roller core 71 is made of polyphenylene sulfide (PPS) and has a thickness of about 0.1 mm.

  The heat generating layer 53 formed on the surface of the roller core 71 is the same as the heat generating layer included in the fixing roller 41 described above. In the heat generating portion 53A, the heat generating layer 53 is interposed between the first electrode portion 59a and the second electrode portion 59b. Of the two regions sandwiched, the current flows only in the region where the electrode insulating portion 50 is not formed, and the heat generating region that generates heat is defined as one region. For this reason, in the heat generation region of the heat generating portion 53A, it is possible to prevent the variation in the electric resistance value in the current flow direction and to make the heat generation amount distribution uniform. Therefore, the temperature distribution in the direction of current flow can be made uniform on the surface of the heat generation support roller 62 corresponding to the heat generation area of the heat generation portion 53A. Therefore, the heat generating support roller 62 can heat the fixing belt 63 so that the temperature distribution on the surface of the fixing belt 63 becomes uniform. Accordingly, a uniform fixing ability in the fixing nip portion formed by the fixing belt 63 and the pressure roller 42 can be achieved. Accordingly, it is possible to obtain a uniform and high-quality fixed image without gloss unevenness and fixing strength variation.

  The length in the width direction, which is the direction corresponding to the axial direction of the heat generating support roller 62 of the heat generating portion 53A, is set longer than the maximum width of the recording paper 1 passing through the fixing nip portion. As a result, the heat generating portion 53A generates heat uniformly in an area corresponding to the width range through which the recording paper 1 passes, and the temperature distribution in the width range through which the recording paper 1 on the surface of the fixing belt 63 passes can be made uniform.

  The protective layer 74 is the outermost layer on the surface of the heat generating support roller 62 and is a layer that contacts the fixing belt 63. Therefore, the protective layer 74 needs to be formed of a material that has heat transfer properties for transferring the heat generated in the heat generating layer 53 to the fixing belt 63 and that can reduce the frictional force with the fixing belt 63. By forming the protective layer 74 in this way, heat is conducted to the fixing belt 63, and even if the fixing belt 63 slides in contact with the heat generating support roller 62, the surface of the heat generating support roller 62 is worn. Can be prevented. Therefore, the heat generating layer 53 formed on the surface of the heat generating support roller 62 can stably generate heat uniformly over a long period of time. Examples of the material constituting the protective layer 74 include fluorine resins such as PFA and PTFE. In the present embodiment, the protective layer 74 has a thickness of 30 μm.

  In the fixing device 60, a heat generation support roller side thermistor 64 is disposed as a temperature detection unit at a position facing the peripheral surface of the heat generation support roller 62 via the fixing belt 63. The heat generation support roller side thermistor 64 detects the temperature of the surface of the fixing belt 63. Then, based on the temperature data detected by the heat generation support roller side thermistor 64, the temperature control unit controls energization to the heat generation layer 53 so that the surface temperature of the fixing belt 63 becomes a predetermined temperature.

  Here, in the present embodiment, the heat generation support roller side thermistor 64 is provided in the fixing belt 63 within a range of a width in contact with the recording paper 1. Accordingly, the temperature control unit can control the energization to the heat generating portion 53A based on the temperature data detected within the range where the heat generating support roller side thermistor 64 is in contact with the recording paper 1, so that the fixing belt can be controlled. In 63, the temperature in the range in contact with the recording paper 1 can be directly controlled with high accuracy.

  The present embodiment as described above is merely an example of the invention, and the configuration can be changed within the scope of the invention. For example, in the image forming apparatus, a configuration example is shown in which a toner image is transferred by a transfer roller onto a recording sheet conveyed by a conveyance belt. However, the present invention is not limited to this, and the transfer mechanism in the image forming apparatus may be configured to use an intermediate transfer belt, or to be directly transferred from a photosensitive drum to a recording sheet.

  In addition, the toner image is electrostatically transferred onto the recording paper and then fixed by heating and pressing with a fixing device. However, the toner image is fixed by heating and pressing simultaneously with the transfer to the recording paper. May be. In such a case, the heat generating layer made of a planar heating element, which is a characteristic configuration in the present invention, may be formed on the surface of the transfer roller, for example.

1 is a diagram illustrating a configuration of an image forming apparatus 100 according to an embodiment of the present invention. 1 is a cross-sectional view illustrating a configuration of a fixing device 40 according to a first embodiment of the present invention. 3 is a cross-sectional view illustrating a configuration of a fixing roller 41 included in the fixing device 40. FIG. FIG. 3 is a developed view of the peripheral surface of a heat generating layer 53 formed on the fixing roller 41. FIG. 6 is a diagram illustrating a heat generation amount distribution and a temperature distribution with respect to the axial direction of the surface of the fixing roller 41 before passing paper. FIG. 6 is a diagram illustrating a temperature distribution, an electrical resistance value distribution, and a heat generation amount distribution with respect to the axial direction of the surface of the fixing roller 41 during paper passing. It is a figure which shows typically the energization state of the heat generating layer 53 surface at the time of paper passing. FIG. 6 is a cross-sectional view illustrating a configuration of a fixing device 60 according to a second embodiment of the present invention. 3 is a cross-sectional view illustrating a configuration of a heat generation support roller 62 included in the fixing device 60. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Visible image formation unit 40,60 Fixing device 41,61 Fixing roller 50 Electrode insulation part 53 Heat generation layer 53A Heat generation part 55 Power reception insulation part 56 Sliding contact part 57 Power reception part 59 Electrode part 62 Heat generation support roller 63 Fixing belt 100 Image formation apparatus

Claims (11)

A fixing roller and a pressure roller facing the fixing roller are provided, and a toner image carried on the recording medium is heated and pressed on the recording medium in a fixing nip portion formed by the fixing roller and the pressing roller. A fixing device for fixing;
The fixing roller surface is formed of a planar heating element having a positive resistance temperature characteristic, and a heating layer is formed that generates heat when current is supplied,
In the heat generating layer, a pair of electrode portions are formed in parallel to the axial direction of the fixing roller so that the flow direction of the current flowing through the heat generating layer is substantially perpendicular to the axial direction of the fixing roller.
The fixing device according to claim 1, wherein in the heat generation layer, a region having a smaller area of two regions sandwiched between the pair of electrode portions is an electrode insulating portion that does not flow current.   The fixing device according to claim 1, wherein the electrode insulating portion is formed such that an area ratio of the electrode insulating portion to an area of the heat generating layer is 0.1% or more and 3% or less.   3. The fixing according to claim 1, wherein the fixing roller has the heat generating layer formed on an outer peripheral surface of a roller base material, and a release layer capable of preventing toner adhesion on the outermost layer. apparatus. Temperature detecting means for detecting the temperature of the surface of the fixing roller;
Temperature control means for controlling the power supplied to the heat generating layer so that the surface temperature of the fixing roller becomes a predetermined temperature based on temperature data detected by the temperature detection means. The fixing device according to claim 1. A contact portion to which a voltage for supplying power to the heat generating layer is applied is provided to face the surface of the fixing roller;
At both ends in the width direction of the heat generating layer, a power receiving portion that receives a current flowing by a voltage applied to the contact portion and supplies the current to the electrode portion is formed over the entire circumferential direction,
5. The power receiving unit according to claim 1, wherein the power receiving unit is configured to slide on the contact unit to receive power when the fixing roller rotates about an axis. 6. Fixing device. An endless fixing belt stretched between a fixing roller and a heat generating support roller, and a pressure roller facing the fixing roller through the fixing belt, the heat generating support roller being in contact with the fixing belt The fixing device heats and fixes the toner image carried on the recording medium onto the recording medium at a fixing nip formed by the fixing belt and the pressure roller. And
The surface of the heat generation support roller is formed of a sheet heating element having a positive resistance temperature characteristic, and a heat generation layer that generates heat when an electric current is supplied is formed.
In the heat generating layer, a pair of electrode portions are formed in parallel with the axial direction of the heat generating support roller so that the flow direction of the current flowing through the heat generating layer is substantially orthogonal to the axial direction of the fixing roller.
The fixing device according to claim 1, wherein in the heat generation layer, a region having a smaller area of two regions sandwiched between the pair of electrode portions is an electrode insulating portion that does not flow current.   The heat generation support roller is characterized in that the heat generation layer is formed on an outer peripheral surface of a support roller base material, and a protective layer capable of reducing a frictional force with the fixing belt is formed on an outermost layer. Item 7. The fixing device according to Item 6. Temperature detecting means for detecting the temperature of the surface of the fixing belt;
Temperature control means for controlling the power supplied to the heat generating layer so that the surface temperature of the fixing belt becomes a predetermined temperature based on the temperature data detected by the temperature detection means. The fixing device according to claim 6 or 7. A contact portion to which a voltage for supplying power to the heat generation layer is applied is provided to face the surface of the heat generation support roller;
At both ends in the width direction of the heat generating layer, a power receiving portion that receives a current flowing by a voltage applied to the contact portion and supplies the current to the electrode portion is formed over the entire circumferential direction,
9. The power receiving unit according to claim 6, wherein the power receiving unit is configured to receive power by sliding on the contact unit when the heat generation support roller rotates about an axis. 10. Fixing device.   The fixing device according to claim 1, wherein a length of the heat generating layer in a width direction is set to be longer than a maximum width of the recording medium passing through the fixing nip portion.   An image forming apparatus comprising the fixing device according to claim 1.

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