JP5386912B2 - Fixing apparatus and image forming apparatus - Google Patents

Description

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

  2. Description of the Related Art In an image forming apparatus using powdered toner, for fixing a formed toner image, an apparatus that heats and pressurizes the toner image to a recording medium is widely used. Such a fixing device includes a fixing member (heating member) that heats an endless peripheral surface, and a pressure member. A sheet-like recording medium is sandwiched between the fixing member and the endless peripheral surface. The recording medium is conveyed along with the circumferential movement of the surface, and the toner image on the recording medium is heated and pressurized.

  As a means for heating the peripheral surface of the fixing member, for example, as described in Patent Document 1, a conductive layer is provided along the peripheral surface of the fixing member, and excitation coils are arranged so as to face each other. Some supply a high-frequency current. An eddy current is generated in the conductive layer by the magnetic field generated by the high-frequency current, and heat is generated.

Patent Document 2 describes a fixing device in which a heating element is arranged so as to be in contact with an inner peripheral surface of a fixing member that is hollow and has an endless outer peripheral portion. An electromagnetic induction heating coil is disposed at a position facing through the fixing member, and the heating element is heated by the action of the generated high-frequency magnetic field to heat the contacting fixing member.
JP 2000-187406 A JP 2008-164783 A

  In the present invention, when a lubricant that reduces friction at the contact portion with the heating element is applied to the inner peripheral surface of the fixing member, the lubricant is more efficiently supplied to the contact portion between the heating element and the fixing member. It is an object of the present invention to provide a fixing device.

In order to solve the above-mentioned problems, the invention according to claim 1 is arranged such that a belt-shaped fixing member whose outer peripheral surface is pressed against a recording medium on which an image is recorded, and an inner peripheral surface of the fixing member are in contact with each other. A pressing member that presses the outer peripheral surface of the fixing member against the recording medium from the inner peripheral surface; a support that supports the pressing member; and the pressing member that is pressed against the pressing member via the fixing member and rotates. A pressure rotator, and a heating element that contacts the inner peripheral surface of the fixing member along a circumferential direction, and the fixing member is coated with a lubricant that reduces friction at a contact portion with the heating element. In the heating element, the upstream end in the circumferential movement direction of the fixing member gradually approaches and contacts the fixing member from a position separated from the fixing member toward the downstream side. It has a shape, the calling A plate-like heat conducting member is superimposed on the opposite side of the surface of the body that contacts the fixing member, and includes a coupling member that couples the heating element and the heat conducting member, and the heating element and the heat conducting member; The upstream end of the fixing member in the circumferential movement direction is coupled to one end of the coupling member, and the other end of the coupling member is connected to the downstream side of the heating element and the heat conducting member. Provided is a fixing device in which ends are coupled .

  According to a second aspect of the present invention, in the fixing device according to the first aspect, the heating element is formed of a plate-like member, and an upstream end in the circumferential movement direction of the fixing member is separated from the fixing member. It is assumed that the support member is supported by a portion separated from the fixing member.

  According to a third aspect of the invention, there is provided the fixing device according to the first or second aspect, wherein the heating element has an end on the upstream side in the circumferential movement direction of the fixing member to be displaced by the displacement of the fixing member. It shall be elastically supported so that it can follow.

According to a fourth aspect of the present invention, in the fixing device according to any one of the first to third aspects, the heating element is curved so that a surface in contact with the fixing member is convex, and the fixing member The upstream end in the circumferential movement direction of the fixing member is separated from the fixing member while being curved with a larger curvature than the circumferential curvature of the fixing member during the circumferential movement.

According to a fifth aspect of the present invention, there is provided an image forming unit that forms a toner image by attaching toner to a latent image due to a difference in electrostatic potential, and the toner image is directly transferred to a recording medium to be conveyed or intermediate A transfer device that transfers the toner image transferred to the recording medium by heating and fixing the toner image transferred to the recording medium after the transfer to the transfer medium; An image forming apparatus, which is a fixing device according to any one of claims 1 to 4 , is provided.

According to the first aspect of the present invention, it becomes easier to support the plate-like heating element and the heat conducting member in close contact with each other as compared with the case where the present configuration is not provided .

  According to the second aspect of the present invention, compared to the case where the present configuration is not provided, the processing of the shape in which the heating element gradually approaches and contacts the fixing member, and the heating element is attached to the support body. It becomes easy.

  According to the third aspect of the present invention, the adhesion to the fixing member is improved as compared with the case where the present configuration is not provided.

According to the fourth aspect of the present invention, it is possible to reduce the scraping off of the lubricant adhering to the fixing member at the upstream end portion of the heating element as compared with the case where this configuration is not provided. Can do.

According to the fifth aspect of the present invention, an increase in the driving torque of the fixing member can be suppressed as compared with the case where the present configuration is not provided.

Hereinafter, embodiments of the invention according to the present application will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention.
The image forming apparatus includes a cylindrical photosensitive drum 1 on which a latent image is formed by irradiating image light after uniform charging. Around the photosensitive drum 1, the photosensitive drum 1 is provided. A charging device 2 that uniformly charges the surface of the photosensitive drum 1, an exposure device 3 that irradiates the photosensitive drum 1 with image light to form a latent image on the surface, and an electrostatic latent image on the photosensitive drum 1 is selected by toner. A transfer roll 5 for transferring a toner image on the photosensitive drum to a recording medium by an electric field formed by applying a transfer bias voltage between the developing device 4 and the photosensitive drum 1 that are visualized by a specific adhesion; And a cleaning device 6 for removing toner remaining on the photosensitive drum 1 after the image is transferred.

  Further, a paper feed tray 7 that stores a recording medium to which the toner image is transferred, and a recording medium fed one by one from the paper feed tray 7 are transferred to the press contact portion 5a where the photosensitive drum 1 and the transfer roll 5 face each other. And a fixing device 20 that heats and presses the toner image transferred to the recording medium, and a discharge roller 9 that sends the recording medium on which the toner image is fixed to the discharge tray 10. It has been.

  In the image forming apparatus as described above, the photosensitive drum 1 is charged to a substantially uniform negative polarity by the charging device 2. The exposure device 3 irradiates the charged surface of the photosensitive drum 1 with image light based on the image data. The exposed portion of the exposed surface of the photosensitive drum 1 has a reduced charging potential, and a non-exposed portion. A latent image is formed due to the potential difference between the two. The developing device 4 holds toner having a negative charge on the peripheral surface of the developing roll 4 a by thinning the toner, and the toner thinned by the rotation of the developing roll 4 a is the peripheral surface of the photosensitive drum 1. It is conveyed to the position facing. An electric field is generated between the photosensitive drum 1 and the developing roll 4a by the developing bias voltage applied between the two, and the toner having a negative charge is transferred to the exposed portion. The toner image formed in this way is conveyed to the transfer pressure contact portion 5a to which the transfer roll 5 is pressed by the rotation of the photosensitive drum 1.

  On the other hand, the recording medium sent out one by one from the paper tray 7 is sent to the transfer pressure contact portion 5a at the timing of contact with the toner image on the photosensitive drum 1. The recording medium contacts the surface of the photosensitive drum 1 on the upstream side of the transfer pressure contact portion 5a, and passes through the transfer pressure contact portion 5a in a close contact state. An electric field is formed around the transfer pressure contact portion 5a and its periphery by a transfer bias voltage, and the toner image is transferred to the recording medium within the electric field.

  The recording medium onto which the toner image has been transferred is sent to the fixing device 20 while holding the toner image. The fixing device 20 heats and presses the toner image on the recording medium and fixes the toner image on the recording medium.

FIG. 2 is a schematic cross-sectional view of the fixing device according to an embodiment of the present invention.
The fixing device 20 is provided along a fixing belt 21 having an endless peripheral surface, a pressure roll 22 in contact with an outer peripheral surface of the fixing belt 21, and an outer peripheral surface of the fixing belt 21. An electromagnetic induction heating device 30 that heats the belt 21, a pressing member 23 that is in contact with the inner peripheral surface of the fixing belt 21 and presses the pressure roll 22 through the fixing belt, and a support that supports the pressing member 23 The main body is composed of the body 24, the heating element 25 disposed in contact with the inner peripheral surface of the fixing belt 21, and the heat conducting member 26 disposed in contact with the inside of the heating element 25. . The heating element 25 and the heat conducting member 26 are supported by the support 24 via leaf springs 27 and 28, and the heating element 25 and the heat conducting member 26 are overlapped by the coupling member 29. It is coupled to the leaf springs 27 and 28.

  The fixing belt 21 is an endless flexible belt having a thin conductive layer, and is supported so as to be capable of circular movement in the circumferential direction (the direction of arrow A shown in FIG. 2). And as shown in FIG. 3, it is comprised from the base layer 21a which consists of a sheet-like member with high heat resistance from the inside, the conductive layer 21b laminated | stacked on the said base layer, and the surface release layer 21c used as the uppermost layer Has been. Further, a lubricant such as silicon oil or fluorine oil is applied to the inner peripheral surface of the base layer, that is, the inner surface 21d of the fixing belt 21, so that the circumferential movement of the fixing belt 21 is made smooth.

The base layer 21a may be made of a synthetic resin having high heat resistance such as polyimide / polyimide amide.
The conductive layer 21b is a layer that generates heat by electromagnetic induction action of a magnetic field generated by the electromagnetic induction heating device 30, and a metal layer of iron, cobalt, nickel, copper, aluminum, chrome, etc. with a thickness of about 1 to 50 μm. What was formed is used.
Since the surface release layer 21c is a layer that is in direct contact with the unfixed toner image transferred onto the recording medium, a material having good release properties is used.

  In the present embodiment, the fixing belt 21 has a circular cross section with an inner diameter of about 30 mm in an unconstrained state, and the base layer 21a has a rigidity of 75 μm so as not to buckle or the like in the width direction. Polyimide is used. The conductive layer 21b is preferably a thin layer so that permanent deformation and cracking do not occur even when the curvature of the fixing belt 21 is large. The conductive layer 21b has a thickness of 10 μm formed on the base layer 21a by means such as vapor deposition or plating. A copper layer is employed. Further, a perfluoroalkoxy fluororesin (PFA) having a thickness of 50 μm is laminated on the conductive layer 21b as the surface release layer 21c.

The pressing member 23 is flexibly deformed by the pressure of the pressure roll 22, and the fixing belt 21 is sandwiched between the pressure roll 22 and the fixing belt 21 and the pressure roll 22 are arranged along the circumferential direction. A fixing nip to be pressed is formed.
The support 24 is formed by combining steel plates, and is fixedly supported by bases that support the respective members of the fixing device at both ends in the axial direction, that is, in the width direction of the fixing belt 21. And it supports the pressing member 23 and opposes the pressing force from the pressure roll 22.

The pressure roll 22 has a metal cylindrical cored bar 22a as a core material, and has a surface release layer 22b on the surface of the cylindrical cored bar. The fixing belt 21 is sandwiched between the pressing member 23 and the pressure roll 22. It is held in a state. Then, the fixing belt 21 is driven to rotate by being driven to rotate in the direction of arrow B shown in FIG. Therefore, when the recording medium on which the unfixed toner image is transferred is sent to the fixing nip where the fixing belt 21 and the pressure roll 22 are pressed, the recording medium is transported and heated and pressurized. ing.
In the present embodiment, as the pressure roll 22, a surface of a cylindrical cored bar 22a having a diameter of 28 mm is coated with PFA having a thickness of 30 μm as the surface release layer 22b.

  The electromagnetic induction heating device 30 is composed of a plate-shaped member having a curved surface, a coil support member 31 disposed so that the inner curved surface faces the outer peripheral surface of the fixing belt 21 with a gap, and the outside of the coil support member 31. The excitation coil 32 supported on the curved surface and supplied with a high frequency current by the excitation circuit 34 and the magnetic field shielding member 33 provided outside the excitation coil 32 constitute a main part. By supplying a high frequency current to the exciting coil 32, a magnetic field is generated, and an eddy current is induced in the conductive layer 21b and the heating element 25 of the fixing belt 21 facing each other to generate heat.

  The heating element 25 is a plate-like member bent into a curved shape following the inner peripheral surface of the fixing belt 21, and is in contact with the inner peripheral surface of the fixing belt 21 coated with a lubricant and It arrange | positions so that the said electromagnetic induction heating apparatus 30 may be interposed. And it is formed with the metal material which heat | fever-generates with the eddy current induced by a high frequency magnetic field, For example, iron, nickel, cobalt, SUS, or these alloys can be used. Further, a nickel (Ni) -iron (Fe) system having a Curie point in a range not lower than the set temperature at which the fixing belt is heated and not higher than the heat resistance temperature of the fixing belt 21, for example, a range from 170 ° C. to 250 ° C., nickel Ni-chromium Cr-iron Fe-based magnetic shunt alloys can also be used.

  The heating element 25 is desirably formed as thin as possible in order to make the temperature rise during heat generation rapid. However, the magnetic field passes through the heating element 25 and reaches the heat conducting member 26 disposed on the back surface of the heating element 25 (the surface opposite to the contact surface with the fixing belt 21), and the heat conducting member 26 generates heat. It is desirable to avoid this, and the thickness should be greater than the skin depth. From this point of view, the thickness of the nickel (Ni) -iron (Fe) heating element 25 is set to 0.3 mm in the present embodiment.

  The heat conducting member 26 is a plate-like member formed following the shape of the inner surface of the heat generating element 25, and is disposed so as to overlap the back surface of the heat generating element 25. Then, the heat conduction from the heating element 25 promotes the uniform temperature of the heating element 25. The heat conductive member 26 is made of a material having a thermal conductivity higher than that of the heating element 25 and can be formed of a metal such as silver, copper, gold, aluminum, or an alloy thereof. In the present embodiment, aluminum is employed and the thickness is 0.4 mm. Further, the rigidity is lower than that of the heating element 25.

  In the vicinity of the upstream end of the heating element 25 in the rotation direction of the fixing belt 21, as shown in FIG. 4, a curvature changing portion 25 a having a large curvature is provided. The front end side of the changing portion 25 a is separated from the fixing belt 21. The tip side of the curvature changing portion 25 a is substantially linear, and this portion is a support portion 25 b supported by the leaf spring 27. Accordingly, the heating element 25 gradually approaches the inner peripheral surface of the fixing belt 21 from the upstream side, and comes into contact with or near the curvature changing portion 25a. As described above, the fixing belt 21 and the tip of the heating element 25 are not in contact with each other on the upstream side in the rotation direction of the fixing belt 21, and are in contact with a gentle curved surface by the curvature changing portion 25a. Compared with the case where the upstream end of the belt does not have such a configuration, the lubricant applied to the inner peripheral surface of the fixing belt 21 is scraped off, or a lot of lubricant is near the upstream end. It is suppressed that it stays. Then, the lubricant is efficiently supplied between the inner peripheral surface of the fixing belt 21 and the heating element 25.

  On the other hand, the downstream end portion of the heating element 25 in the rotation direction of the fixing belt 21 is also provided with a curvature changing portion 25c having a larger curvature like the upstream end portion, and the vicinity 25d of the tip is separated from the fixing belt 21. The separated portions are supported by the leaf spring 28.

  Both end portions 26a and 26b in the circumferential direction of the heat conducting member 26 arranged so as to overlap the back surface of the heating element 25 have a large curvature at positions corresponding to the curvature changing portions 25a and 25c, similarly to the heating element 25. It is bent. And as shown in FIG. 4, it is supported by the leaf | plate springs 27 and 28 with the heat generating body 25. As shown in FIG.

  As shown in FIG. 5, the plate springs 27 and 28 support the heating element 25 and the heat conducting member 26 at one or more positions at both ends in the width direction of the fixing belt 21 or at both ends and the center. And are fixed so as to be paired on both sides of the support 24 at each position. And it protrudes to both sides in the direction which advances and retreats with respect to the fixing belt 21 at the center of the circumferential direction of the heating element 25, that is, the direction shown by the arrow C in FIG. Joining portions 27b and 28b for connecting the heating element 25 and the heat conducting member 26 are continuously provided at the leading ends of the overhanging portions 27a and 28a, and are substantially parallel to the support portions 25b and 25d of the heating element 25. It is bent like so. The joint portions 27 b and 28 b are overlapped with the heating element 25 and the heat conducting member 26, and these are coupled by a coupling member 29. As a result, the heating element 25 and the heat conducting member 26 are supported so as to be displaceable by bending deformation of the projecting portions 27 a and 28 a of the leaf spring, and elastically follow the fixing belt 21. .

For the joining of the leaf springs 27 and 28, the heating element 25 and the heat conducting member 26, the structure described below can be employed.
The support portions 26a and 26b of the heat conducting member 26 are overlapped on the inner side of the joint portions 27b and 28b of the leaf spring, that is, the support side, and the support portions 25b and 25d of the heating element are overlapped on the outer side. Then, through holes are opened at corresponding positions of the leaf springs 27 and 28, the heating element 25, and the heat conducting member 26, and the protrusions 29a and 29b of the coupling member 29 are inserted into the through holes. .
The coupling member 29 is formed by bending a metal plate and is a member continuous in the width direction of the fixing belt 21. In this embodiment, aluminum is used as the coupling member 29, but when a magnetic field leaks from the exciting coil 32 to the inside of the heat conducting member 26 by using a nonmagnetic metal, the magnetic field is transferred to the support 24. Acting is suppressed. In addition, the coupling member 29 includes protrusions 29a and 29b so that the heating element 25 and the heat conducting member 26 protrude to positions where they overlap with the leaf springs 27 and 28, respectively. The protrusions 29a and 29b are inserted through the through holes of the plate springs 27 and 28, the heating element 25, and the heat conducting member 26 to couple these members, and the coupling member 29 is also supported by the plate springs 27 and 28. It is not in contact with the support 24.

  The heat conducting member 26 is in contact with the inside of the leaf springs 27, 28, the leading edges 26c, 26d are abutted against the overhanging portions 27a, 28a of the leaf spring, and the protrusions 26e, 26f provided at the tip are overhanging portions 27a, 26a. The position is regulated by being inserted through a hole provided from 28a to the joint portions 27b and 28b. The heating element 25 is coupled to the leaf springs 27 and 28 in a state where a tensile force is introduced in the circumferential direction of the fixing belt 21 and pressed against the curved peripheral surface of the heat conducting member 26. In this coupling, projections 29a and 29b of coupling members inserted into the through-holes of the leaf springs 27 and 28 are inserted into through-holes provided at both ends of the heating element 25, and the projections 29a and 29b generate heat. Hang both ends of the body 25. At this time, a tensile force is transmitted from the heat generating material 25 to one surface 29c, 29d of the projections 29a, 29b of the coupling member, and the opposite surfaces 29e, 29f are pressed against the edges of the through holes of the leaf springs 27, 28. As a result, the reaction force of the tensile force of the heating element 25 coupled to the leaf springs 27 and 28 is transmitted to the leaf springs 27 and 28. On the other hand, the heat conducting member 26 generates a compressive force in the circumferential direction when the heating element 25 is pressed, and is transmitted from the tip to the projecting portions 27 a and 28 a of the leaf springs 27 and 28. The reaction force of the compressive force is canceled by the reaction force of the tensile force acting on the leaf springs 27 and 28 from the heating element 25, and the heating element 25 and the heat conducting member 26 are pressed against the leaf springs 27 and 28 while being pressed against each other. Supported. As a result, the adhesiveness between the heating element 25 and the heat conducting member 26 is enhanced, and efficient heat conduction is generated from the heating element 25 to the heat conducting member 26, and the temperature uniformity of the heating element 25 is promoted.

  Further, even when the support 25 supporting the pressing member 23 is bent by the pressing of the pressure roll 22, the heating element 25, the heat conducting member 26, and the like are deformed by the deformation of the projecting portions 27a and 28a of the leaf springs 27 and 28. Is elastically displaced, and the heating element 25 and the heat conducting member 26 are easily maintained in close contact with the fixing belt 21.

In such a fixing device 20, when the pressure roll 22 is rotationally driven, the contacting fixing belt 21 is driven in the circumferential direction, and the recording medium on which the toner image is held is the pressure roll 22 and the fixing belt 21. It is sent in between.
On the other hand, a high frequency current is supplied from the excitation circuit 34 to the excitation coil 32 of the electromagnetic induction heating device 30, and the magnetic flux repeatedly generates and disappears around the excitation coil 32. When this magnetic flux crosses the conductive layer 21b of the fixing belt 21, an eddy current is generated in the conductive layer of the fixing belt 21 so as to generate a magnetic field that hinders the change of the magnetic field, and Joule heat is generated.
Further, the heating element 25 arranged in contact with the inner peripheral surface of the fixing belt 21 also generates heat by the action of the magnetic field of the electromagnetic induction heating device 30 and heats the fixing belt 21. Further, the heat conducting member 26 disposed so as to overlap the back surface of the heat generating element 25 makes the temperature of the heat generating element 25 uniform by heat conduction from the heat generating element 25. As a result, the fixing belt 21 is heated to a temperature suitable for fixing the toner image, and moves to the fixing nip portion where the pressure roll 22 is pressed. The recording medium sent to the fixing nip is pressed against the fixing belt 21, and the toner image is heated and pressurized and pressed onto the recording medium. The recording medium that has passed through the fixing nip is peeled off from the fixing belt 21 or the pressure roll 22 and sent to the paper discharge roll 10.

  When the fixing belt 21 is driven to circulate as described above, the upstream end of the heating element 25 gradually approaches and contacts the fixing belt 21 toward the downstream side, so that it is applied to the inner peripheral surface of the fixing belt. The lubricant 21d is hardly scraped off, and the lubricant is efficiently fed into the contact portion.

In the embodiment described above, the fixing belt has a three-layer structure. However, an elastic layer is provided between the conductive layer and the surface release layer in order to improve the fixing property and image quality of the toner image, or an adhesive layer is provided. A layer or a protective layer for each layer may be provided. Alternatively, a heat resistant resin layer may be laminated on the conductive layer, and the conductive layer may be sandwiched between the two heat resistant resin layers.
Further, a fixing belt having a two-layer structure that does not have a conductive layer may be used. At this time, the fixing belt is heated only by heat conduction from the heating element.

  On the other hand, the heating element is heated by the electromagnetic induction heating device 30 in the above embodiment, but a planar heating element that generates heat when directly energized can also be used. When such a planar heating element is used, it is desirable to provide a power supply device that supplies power to the planar heating element, and this power supply device includes a power storage unit including a battery, a capacitor, and the like. The power storage unit is set so as to be charged except during fixing, and power is supplied from the power storage unit to the sheet heating element during fixing when a large amount of power is supplied to the electromagnetic induction heating device. This suppresses the amount of power used during fixing.

  In this embodiment, silicon oil or fluorine oil, which is a lubricant, is applied in advance to the inner peripheral surface of the fixing belt. However, an oil supply device is provided inside the fixing belt, and a lubricant is appropriately added. It may be applied.

  In the above-described embodiment, the heating element 25 is bent so that both end portions in the circumferential direction are curved with a curvature larger than the curvature of the fixing belt 21 when the fixing belt 21 is rotated, and is separated from the fixing belt 21. Only the end located at the position may be separated from the fixing belt 21. Further, the heating element 25 may have a structure in which the upstream end portion does not have a portion that is curved with a curvature larger than the curvature of the fixing belt 21 when the fixing belt 21 rotates, and is linearly separated from the fixing belt 21. .

In the fixing device that efficiently supplies the lubricant to the contact portion between the heating element and the fixing member, a heating element 41 and a heat conducting member 42 as shown in FIG. 6 may be used. In this fixing device, the heat generating member 41 laminated with the heat conducting member 42 is formed so that the thickness gradually increases from the upstream end, and gradually approaches and contacts the inner peripheral surface of the fixing belt 21. It is comprised as follows. Further, as shown in FIG. 7, the thickness of the end portion of the heating element 43 can be changed and the end 44 a of the laminated heat conducting member 44 can be covered. Thereby, even if the lubricant stays upstream of the contact portion between the heating element 43 and the fixing belt 21, the lubricant is prevented from entering between the heating element 43 and the heat conducting member 44.
In FIGS. 6 and 7, reference numeral 45 indicates a support, and reference numeral 46 indicates a leaf spring.

1 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a schematic configuration diagram illustrating a fixing device that is used in the image forming apparatus illustrated in FIG. 1 and is an embodiment of the present invention. FIG. 3 is an enlarged cross-sectional view of a fixing belt used in the fixing device shown in FIG. 2. FIG. 3 is an enlarged sectional view showing a part of the fixing device shown in FIG. 2. FIG. 3 is a schematic perspective view showing a heating element used in the fixing device shown in FIG. 2. FIG. 9 is a schematic configuration diagram illustrating another example of a fixing device that efficiently supplies a lubricant to a contact portion between a heating element and a fixing member . FIG. 9 is a schematic configuration diagram illustrating another example of a fixing device that efficiently supplies a lubricant to a contact portion between a heating element and a fixing member .

DESCRIPTION OF SYMBOLS 1: Photosensitive drum, 2: Charging apparatus, 3: Exposure apparatus, 4: Developing apparatus, 5: Transfer roll, 5a: Transfer press-contact part, 6: Cleaning apparatus, 7: Paper tray, 8: Conveyance path, 9: Ejection Paper roll, 10: paper discharge tray, 20: fixing device, 21: fixing belt, 22: pressure roll, 23: pressing member, 24: support, 25: heating element, 25a, 25c: curvature change portion of heating element 25b, 25d: heating element support part, 26: heat conducting member, 27, 28: leaf spring, 27a, 28a: leaf spring overhanging part, 27b, 28b: leaf spring joining part, 29: coupling member, 29a , 29b: projection of the coupling member, 30: electromagnetic induction heating device, 31: coil support member, 32: excitation coil, 33: magnetic field shielding member, 34: excitation circuit, 41, 43: heating element, 42, 44: heat conduction Members, 45 Support, 46: leaf spring

Claims (5)

A belt-shaped fixing member whose outer peripheral surface is pressed against a recording medium on which an image is recorded;
A pressing member that is disposed in contact with the inner peripheral surface of the fixing member and presses the outer peripheral surface of the fixing member against the recording medium from the inner peripheral surface;
A support that supports the pressing member;
A pressure rotating body that is pressed against the pressing member via the fixing member and rotates;
A heating element that contacts the inner circumferential surface of the fixing member along the circumferential direction,
The fixing member is coated with a lubricant that reduces friction at a contact portion with the heating element,
The heating element has a shape in which an upstream end in the circumferential movement direction of the fixing member gradually approaches and contacts the fixing member from a position separated from the fixing member toward the downstream side ,
A plate-like heat conduction member is superimposed on the opposite side of the surface of the heating element that contacts the fixing member,
A coupling member that couples the heating element and the heat conducting member;
An upstream end of the heating member and the heat conducting member in the circumferential movement direction of the fixing member is coupled to one end of the coupling member, and the heating element is coupled to the other end of the coupling member. A fixing device having a downstream end connected to the heat conducting member . The heating element is made of a plate-like member, and the upstream end portion in the circumferential movement direction of the fixing member is bent so as to be separated from the fixing member,
The fixing device according to claim 1, wherein the fixing device is supported by the support at a portion spaced apart from the fixing member.   2. The heating element is elastically supported so that an upstream end portion in a circumferential movement direction of the fixing member can follow a displacement of the fixing member in contact therewith. The fixing device according to claim 2. The heating element is curved so that the surface in contact with the fixing member has a convex shape, and the upstream end in the circumferential movement direction of the fixing member is larger than the curvature in the circumferential direction during the circumferential movement of the fixing member. The fixing device according to any one of claims 1 to 3 , wherein the fixing device is separated from the fixing member while being curved with a curvature. An image forming unit that forms a toner image by attaching toner to a latent image due to a difference in electrostatic potential;
A transfer device that directly transfers the toner image to a transported recording medium or transfers the toner image to an intermediate transfer member, and then transfers the toner image to a transported recording medium;
A fixing device that heats and fixes the toner image transferred to the recording medium to the recording medium,
The image forming apparatus according to claim 1 , wherein the fixing device is a fixing device according to claim 1 .

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