Fixing device and image forming apparatus

Abstract

To solve side tracking in an axial direction of a fixing belt caused by compressive deformation of a sponge-like elastic layer in a nip forming unit.SOLUTION: A fixing device sandwiches a fixing belt in a pressure contact state with a support pad and a pressure roller 32 to form a nip part, drives the pressure roller 32 to cause the fixing belt to travel, and passes a sheet on which an unfixed image is formed through the nip part to fix the image. The pressure roller 32 is provided with a sponge-like elastic layer. The fixing device includes bearing parts 310 that hold a rotation shaft 321 of the pressure roller 32 movably and tiltably in its axial direction, and a tilting mechanism 320 that converts a moving force in the axial direction generated in the pressure roller 32 into a tilting force to tilt the rotation shaft 321 of the pressure roller 32 in a direction for correcting side tracking of the fixing belt 31.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to a fixing device that uses a fixing belt to thermally fix an unfixed image on a sheet and an image forming apparatus including the fixing device, and in particular to a technique for eliminating deviation of the fixing belt. [Background technology]

[0002] Electrophotographic image forming apparatuses include a fixing device that thermally fixes a sheet on which an unfixed toner image has been formed by passing the sheet through a nip portion formed between a heating rotator and a pressure rotator.

[0003] In recent years, from the viewpoint of energy saving, fixing devices using a fixing belt system have been widely adopted in which a fixing belt is stretched between a heating roller, which is a heat source, and a long support such as a support pad or a support roller, and the fixing belt is sandwiched between the support and a pressure roller to form a nip portion.

[0004] The fixing belt is formed primarily from metal or resin materials, is relatively thin, and has a small heat capacity. This reduces the time it takes to heat up to the fixing temperature when the device is started up or from standby mode, thereby contributing to energy savings.

[0005] However, if the dimensional accuracy of the heating roller or support varies or the installation accuracy is insufficient, the fixing belt may move in the axial direction and meander or slant. Such meandering or slant (hereinafter referred to as "slant, etc.") may cause the toner image to shift position during fixing, or may cause the fixing belt itself to be damaged by contacting for a long time with a flange or the like that is intended to restrict the fixing belt from moving (leaning) in the axial direction beyond a certain level.

[0006] In order to suppress the occurrence of skewing or the like of the fixing belt, for example, Patent Documents 1 and 2 disclose a configuration in which the rotation axis of a driven roller that is not involved in forming the nip portion, among multiple rollers that tension the fixing belt, such as the heating roller, is tilted relative to the rotation axes of the other rollers to eliminate skewing or the like in the axial direction of the fixing belt (adjusting the inclination of the rotation axis of a specific roller in this manner will hereinafter be referred to as "alignment adjustment"). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2012-198293 A [Patent Document 2] JP 2013-228428 A [Patent Document 3] JP 2008-169047 A Summary of the Invention [Problem to be solved by the invention]

[0008] In fixing devices, in order to prevent poor fixing, an elastic layer is formed on the pressure roller and this is pressed against the fixing belt with strong force to ensure a nip pressure and nip width greater than a specified level. Recently, in order to achieve further energy savings, it has become mainstream to adopt a highly insulating sponge-like elastic layer.

[0009] However, because the elastic layer is manufactured by molding, partial differences in molding conditions inevitably occur when the molten elastic material is poured into the mold and when it is cooled inside the mold, resulting in anisotropy in the arrangement of the cells (the units of the air bubble structure that make up the foam) in the sponge-like elastic layer.

[0010] This results in a large axial moving force being applied to the fixing belt when the elastic layer in the nip portion is compressed and deformed.

[0011] 12A and 12B are schematic diagrams for explaining the principle of how a moving force in the axial direction is generated on the fixing belt when the elastic layer of the pressure roller is compressed and deformed.

[0012] FIG. 12A shows a cross section of the elastic layer 62a formed around the shaft core 621 of the pressure roller 62 when the fixing belt 61 is not pressed against the elastic layer 62a.

[0013] The hatching in the figure shows the main arrangement direction of the cells, and in this example, the main arrangement direction of the cells is inclined to the right.

[0014] When pressure roller 62 is pressed against fixing belt 61 as shown in FIG. 12(b), elastic layer 62a is compressed and deformed such that the cell arrangement is further tilted to the right (X1 direction), and the surface shifts by Δx in the X1 direction.

[0015] Since the fixing belt 61 is in close contact with the surface of the elastic layer 62a due to a strong pressure contact force, the fixing belt 61 also moves in the X1 direction (hereinafter, this axial movement of the fixing belt may be simply referred to as "deviation"). As a result, the fixing belt 61 becomes skewed.

[0016] As a result of the inventors' considerations, it was found that in such cases, conventional methods such as those described in Patent Documents 1 and 2, which involve adjusting the alignment of rollers that are not involved in forming the nip portion, are not sufficient to completely correct the bias of the fixing belt.

[0017] This is thought to be because the pressure contact force of the pressure roller 62 is large to form the nip portion, and the adhesion between the surface of the fixing belt 61 and the surface of the pressure roller 62 is high, so that the axial force applied to the fixing belt 61 by the sponge-like elastic layer 62a in the case shown in Figure 12(b) is much larger than the skew, etc. that occurs due to other conventional factors.

[0018] On the other hand, Patent Document 3 discloses a configuration for adjusting the alignment of a pressure roller for forming a nip portion.

[0019] FIG. 13 is a diagram showing an outline of the fixing device disclosed in the above-mentioned Patent Document 3. As shown in FIG.

[0020] Fixing belt 71 is stretched around heating roller 73 and output roller 74, and pressure roller 72 is pressed against it to form a nip portion, and an unfixed sheet S is passed through the nip portion to perform fixing. In Patent Document 3, output roller 74 is configured to be driven.

[0021] The position of the axial edge of the fixing belt 71 is monitored by photoelectric sensors 711, 712. When the photoelectric sensor 711 or 712 detects a deviation of the fixing belt 71, the control means 75 drives the drive motor 761 in the alignment section 76 to rotate the eccentric gear 762 and tilt the rotation axis of the pressure roller 72 in a direction to eliminate the deviation of the fixing belt 71, thereby adjusting the alignment.

[0022] However, it has been found that the configuration of Patent Document 3 does not solve the offset of the fixing belt that occurs when a sponge-like elastic material is used as the elastic layer of the pressure roller.

[0023] Moreover, according to the configuration of Patent Document 3, photoelectric sensors 711 and 712, control means 75, drive motor 761, etc. are required to adjust the alignment of pressure roller 72, which inevitably leads to a significant increase in costs.

[0024] The present disclosure has been made in consideration of the above circumstances, and aims to provide a fixing device and an image forming apparatus having the fixing device that can effectively suppress, with a simple configuration that is low in cost, the offset of a fixing belt that occurs when a nip forming member has a sponge-like elastic layer to save energy. [Means for solving the problem]

[0025] In order to achieve the above-mentioned object, a fixing device according to one embodiment of the present disclosure is a fixing device in which a fixing belt is pressed and sandwiched between a long-sized support and a drive roller to form a nip portion, the drive roller is driven to run the fixing belt, and a sheet on which an unfixed image has been formed is passed through the nip portion to be fixed, the fixing device being characterized in that a sponge-like elastic layer is provided on at least one of the support and the drive roller, and the fixing device is equipped with a bearing portion that holds the shaft of the drive roller so that it can move and tilt in its axial direction, and a conversion mechanism that converts the axial moving force of the drive roller into a tilting force that tilts the shaft of the drive roller in a direction to correct the deviation of the fixing belt.

[0026] Moreover, one aspect of the present disclosure includes a drive transmission unit that transmits the driving force of a drive shaft of a drive source to a shaft of the drive roller, and the drive transmission unit has the function of the conversion mechanism.

[0027] The drive transmission unit includes a first gear attached to the drive shaft of the drive source and a second gear attached to the shaft of the drive roller and meshing with the first gear, and at least one of the first gear and the second gear is a tapered gear, thereby having the function of the conversion mechanism.

[0028] The roller also has a restricting means for restricting the range of movement of the drive roller in the axial direction.

[0029] Here, it is preferable that the regulating means regulates the axial movement range of the drive roller so that the meshing tooth width between the first gear and the second gear does not become equal to or smaller than a certain width.

[0030] The second gear is disposed on the upstream side or downstream side of the first gear in the running direction of the fixing belt in the nip portion.

[0031] In another aspect of the present disclosure, the drive transmission section includes a first coupling member attached to one of the drive shaft of the drive source and the shaft of the drive roller, and having an engagement recess, and a second coupling member attached to the other shaft and inserted into the engagement recess of the first coupling member to engage with said recess, and the engagement surface of at least one of the first coupling member and the second coupling member is formed in a tapered shape that forms an angle with respect to the direction of the attached shaft, thereby providing the function of the conversion mechanism.

[0032] Here, it is preferable that the axis of the drive shaft of the drive source is shifted upstream in the running direction of the fixing belt with respect to the axis of the drive roller.

[0033] In addition, Drive It is preferable to provide a biasing means for biasing the shaft of the roller toward the downstream side in the running direction of the fixing belt in the nip portion.

[0034] Here, it is preferable to have a restricting means for restricting the axial movement range of the drive roller.

[0035] It is also desirable that the conversion mechanism tilts the drive roller within a plane that is parallel to the longitudinal direction of the support and parallel to a plane that includes at least a portion of the nip portion formed when the drive roller is pressed against the fixing belt.

[0036] In addition, an image forming apparatus according to another aspect of the present disclosure is an image forming apparatus including an image creating unit that forms an unfixed image on a sheet, and a fixing unit that thermally fixes the unfixed image to the sheet, and is characterized in that the above-mentioned fixing device is used as the fixing unit. Effect of the Invention

[0037] In the fixing device according to the above disclosed aspect, the drive roller is held by the bearing portion so that it can move axially and tilt, and a nip portion is formed, so that when an axial moving force is generated on the fixing belt due to compressive deformation of a sponge-like elastic layer on at least one of the support body and the drive roller, a force that moves the drive roller in the axial direction is also generated, and the moving force is converted by the conversion mechanism into a force that tilts the drive roller, and alignment adjustment is performed autonomously.

[0038] In this case, the driving roller itself, not the driven roller, tilts and applies a strong force to the fixing belt in the nip portion in a direction to eliminate the bias, so that the bias of the fixing belt is effectively corrected. In addition, the mechanism for converting the linear movement amount in the axial direction of the driving roller into the amount of tilt can be constructed relatively simply, so that an increase in costs can be suppressed. [Brief description of the drawings]

[0039] [Figure 1] 1 is a schematic diagram illustrating an overall configuration of a printer including a fixing device according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a cross-sectional view illustrating a schematic configuration of a fixing unit of the printer. [Diagram 3] 1A and 1B are diagrams for explaining the operating principle of correcting misalignment of a fixing belt by the alignment mechanism according to the present disclosure, in which (a) is a schematic diagram showing the direction of the forces acting on the fixing belt and the pressure roller when the pressure roller is pressed against the fixing belt, and (b) is a schematic diagram showing the state in which the axis of the pressure roller is tilted to correct axial misalignment of the fixing belt. [Figure 4] 4 is a perspective view showing a specific configuration of an alignment adjustment mechanism for a pressure roller in the fixing device according to the first embodiment of the present disclosure. FIG. [Diagram 5] 5A and 5B are schematic diagrams illustrating how deviation of a fixing belt in the fixing device is corrected by an alignment mechanism. [Figure 6]6 is a schematic diagram for explaining how the fixing belt is corrected by an alignment mechanism when the fixing belt is misaligned in the opposite direction to that in FIG. 5(a). FIG. [Figure 7] 11 is a side view showing the meshing state of the tapered gears and the state of the bearings in the alignment mechanism. FIG. [Figure 8] 13A and 13B are partial perspective views for explaining an alignment mechanism of a fixing device according to a second embodiment of the present disclosure. [Figure 9] 13A and 13B are schematic diagrams illustrating an operation of correcting deviation of a fixing belt by an alignment mechanism according to the second embodiment. [Figure 10] 9A and 9B are schematic diagrams for explaining how the fixing belt is corrected by an alignment mechanism when the fixing belt is misaligned in the opposite direction to that in FIG. 9A. [Figure 11] 13A and 13B are schematic cross-sectional views showing modified examples of a fixing belt type fixing device. [Figure 12] 1A and 1B are schematic diagrams for explaining the principle by which a pressure roller having a sponge-like elastic layer is pressed against a fixing belt, thereby generating a moving force applied to the fixing belt from the pressure roller. [Figure 13] 1A and 1B are diagrams illustrating an example of an alignment mechanism in a conventional fixing belt type fixing device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] Hereinafter, a tandem color printer (hereinafter simply referred to as a "printer") will be described as an example of an image forming apparatus equipped with a fixing device according to an embodiment of the present disclosure with reference to the drawings.

[0041] <First embodiment> (1) Overall configuration of the printer FIG. 1 is a schematic cross-sectional view showing the overall configuration of a printer 1.

[0042] As shown in the figure, printer 1 is an electrophotographic printer that includes a feeding section 10, an image creating section 20, a fixing section 30, an ejection section 40 and a duplex conveying section 50, and is capable of executing a single-sided print job in which an image is printed on only one side (the front side) of a recording sheet S, and a double-sided print job in which an image is printed on both sides (the front and back sides) of sheet S.

[0043] The feeding section 10 includes a paper feed tray 11 that stores sheets S, a feed roller 12P that is provided in the paper feed tray 11 and feeds the sheets S one by one toward a transport path 19, a paper feed roller 12F that feeds and transports the fed sheets S, and a timing roller 13 for timing the sending of the sheets S to a secondary transfer position 29.

[0044] The imaging section 20 forms a toner image on the sheet S sent from the feeding section 10. Specifically, the four imaging units 21Y, 21M, 21C, and 21K expose the surfaces of the charged photoconductor drums 25Y, 25M, 25C, and 25K to laser light from an exposure section 26 that is modulated and driven based on image data, create electrostatic latent images on the surfaces, and develop the electrostatic latent images with toners of the respective colors of yellow (Y), magenta (M), cyan (C), and black (K).

[0045] The four color toner images visualized by development are primarily transferred from the surfaces of the photoconductor drums 25Y, 25M, 25C, and 25K to the surface of the intermediate transfer belt 23 by an electric field between the photoconductor drums 25Y, 25M, 25C, and 25K and the primary transfer rollers 22Y, 22M, 22C, and 22K that face the photoconductor drums 25Y, 25M, 25C, and 25K via the intermediate transfer belt 23. In this primary transfer, the timing of forming the toner images in the imaging units 21Y to 21K is shifted so that the Y to K toner images are transferred to the same position on the intermediate transfer belt 23. As a result, a color toner image is formed on the intermediate transfer belt 23 by multiple transfer of the Y to K toner images.

[0046] Intermediate transfer belt 23 is located above photoconductor drums 25Y to 25K, stretched around multiple rollers including drive roller 23R and driven roller 23L, and rotates in the direction of arrow A. The color toner image on intermediate transfer belt 23 moves to secondary transfer position 29, which is the contact position between intermediate transfer belt 23 and secondary transfer roller 24, as intermediate transfer belt 23 rotates.

[0047] At a secondary transfer position 29, the color toner image on the intermediate transfer belt 23 is secondarily transferred to a front surface (first surface) of the sheet S when the sheet S conveyed from the feeding unit 10 passes between the intermediate transfer belt 23 and the secondary transfer roller 24 due to an electric field between the intermediate transfer belt 23 and the secondary transfer roller 24. The sheet S onto which the color toner image (unfixed image) has been secondarily transferred is conveyed by the secondary transfer roller 24 in the direction of arrow E toward the fixing unit 30.

[0048] The fixing unit 30 includes a fixing belt 31 and a pressure roller 32, and the color toner image is thermally fixed onto the sheet S by passing the sheet S through a nip portion Np formed between the fixing belt 31 and the pressure roller 32.

[0049] The discharge section 40 includes discharge rollers 41 and a paper discharge port 45, and discharges the sheet S on which the color toner image has been fixed from the paper discharge port 45. The discharge rollers 41 are disposed inside the paper discharge port 45, and while rotating in the direction of arrow B (forward rotation), transport the sheet S transported from the fixing section 30 from the paper discharge port 45 and discharge it outside the machine. The discharged paper S is stored in the paper discharge tray 46. This completes single-sided printing, in which printing is performed only on the first side of the sheet S.

[0050] In addition, in the case of a double-sided print job, the sheet S that has passed the secondary transfer position 29 during printing on the front side (first side) is transported from the fixing unit 30 to the discharge rollers 41. When the trailing end in the transport direction of the sheet S transported by the discharge rollers 41 passes the detection position of the discharge sensor ES consisting of an optical sensor, the discharge rollers 41 switch from forward rotation to reverse rotation (rotation in the direction of arrow C).

[0051] As a result of the reversal of the discharge roller 41, the sheet S is inverted and guided to the double-sided conveying section 50, where it is conveyed along the double-sided conveying path in the direction of arrow D by double-sided conveying rollers 51, 52, 53, 54, and 55, and then conveyed again to the secondary transfer position 29 via the timing roller 13, where the color toner image is secondarily transferred to the back surface (second surface) of the sheet S, and after being thermally fixed in the fixing section 30, the sheet is discharged to the output tray 46 via the discharge roller 41.

[0052] In the feeding section 10 and the imaging section 20, rotating members including the paper feeding and transporting rollers, the driving roller 23R, and the photoconductor drums 25Y-25K are rotated by the driving force of a driving motor M1 arranged in the imaging section 20. In addition, the pressure roller 32 in the fixing section 30 is driven to rotate by a driving motor (fixing motor) M2, the discharge roller 41 rotates forward and backward by the driving force of a driving motor M3 arranged in the discharge section 40, and the double-sided transport rollers 51-55 are rotated by the driving force of a driving motor M4 arranged in the double-sided transport section 50.

[0053] The control unit 100 is also connected to an external terminal device via a network, receives print job data sent from the terminal device, generates image data to be printed from the received print job data, and provides the generated image data for printing.

[0054] (2) Configuration of the fixing unit (2-1) Overview of the fixing section FIG. 2 is a schematic cross-sectional view showing the configuration of the fixing unit 30. As shown in FIG.

[0055] As shown in the figure, the fixing section 30 includes a fixing belt 31 stretched between a heating roller 34 (heating section) and a long support pad (support) 33, and a pressure roller 32 pressed against the support pad 33 to form a nip.

[0056] In FIG. 2, the direction of the axis of the heating roller 34 (longitudinal direction) is the X-axis, the vertical direction is the Z-axis, and the direction perpendicular to the XZ-axis is the Y-axis (the same applies to the following drawings).

[0057] The support pad 33 is arranged so that its longitudinal direction is parallel to the rotation axis of the heating roller 34, and the surface (support surface 33a) of the support pad 33 that backs up the fixing belt 31 against the pressure of the pressure roller 32 is arranged so that it is parallel to the XZ plane.

[0058] The fixing belt 31 is formed by laminating, in the order mentioned, a base layer made of polyimide or SUS (stainless steel), an elastic layer made of a highly heat-resistant material such as silicone rubber or fluororubber, and a release layer made of a fluorine-based resin such as PFA (perfluoroalkoxy fluorine resin) with releasability.

[0059] The pressure roller 32 has a cylindrical core metal made of aluminum, iron, etc., and a sponge-like elastic layer 32a made of a highly heat-resistant elastic material such as silicone rubber laminated on the outer circumferential surface of the core metal. A release layer (not shown) such as PFA may be further laminated on the outermost layer.

[0060] A rotation shaft 321 (see FIG. 4) of the pressure roller 32 is supported by a bearing portion 310 (described later) so as to be movable in the axial direction and tiltable.

[0061] The outer circumferential surface of the pressure roller 32 is pressed against the outer circumferential surface of the fixing belt 31 with a predetermined load (pressure contact force) by the biasing force of an elastic member (not shown) such as a spring. This pressing forms a nip portion Np between the outer circumferential surface of the pressure roller 32 and the outer circumferential surface of the fixing belt 31.

[0062] The pressure roller 32 is driven to rotate at a predetermined rotation speed in the direction of arrow P by the rotational driving force of the fixing motor M2 (FIG. 1), and functions as a drive roller. The rotation of the pressure roller 32 causes the heating roller 34 and the fixing belt 31 stretched between the heating roller 34 and the support pad 33 to rotate (run) in the direction of arrow Q.

[0063] When a fixing job is performed, the rotation speed of the fixing motor M2 (FIG. 1) is controlled by the control 100 so that the conveying speed of the sheet S passing through the nip portion Np is stabilized at a predetermined system speed (reference speed).

[0064] In this embodiment, when the fixing belt 31 is offset in one axial direction, the alignment adjustment mechanism 300 (FIG. 4) tilts the rotation shaft 321 of the pressure roller 32 by a predetermined amount to correct the offset of the fixing belt 31. This will be described in detail later.

[0065] The heating roller 34 is formed, for example, by laminating a coating layer made of PTFE (polytetrafluoroethylene) on the outer surface of a cylindrical aluminum hollow core, and both axial ends thereof are supported for free rotation by a frame (not shown) that constitutes the housing of the fixing unit 30.

[0066] A heater section 341 is inserted into the inner periphery of the cylindrical heating roller 34, and is made up of a first heater 3411 that heats almost the entire range in the axial direction (longitudinal direction: the direction into the paper in FIG. 2) of the heating roller 34, and a second heater 3412 that heats the central portion in the axial direction, and generates heat by power supply from a power source (not shown), thereby heating the heating roller 34. In this embodiment, the first heater 3411 and the second heater 3412 are made up of halogen heaters, but they may be other heat sources.

[0067] In this embodiment, the support pad 33 is made of resin and is elongated and parallel to the axis of the heating roller 34. It abuts against the back surface of the fixing belt 31 to support it, and also clamps the fixing belt 31 between itself and the pressure roller 32 to form a nip portion.

[0068] To reduce friction, a surface treatment and / or a lubricant is applied to the surface of support pad 33 that comes into sliding contact with fixing belt 31. Support pad 33 is fixed and supported by a frame of fixing unit 30 (not shown).

[0069] When the heater unit 341 is energized while the fixing belt 31 is rotating, heat generated from the heater unit 341 is transmitted from the heating roller 34 to the fixing belt 31, and reaches the nip portion Np as the fixing belt 31 rotates.

[0070] As a result, heat from the fixing belt 31 is supplied to the pressure roller 32 and the support pad 33, and the temperature of the nip portion Np, which is the contact area between the fixing belt 31 and the pressure roller 32, increases.

[0071] A temperature sensor (not shown) is disposed near the portion of the fixing belt 31 that comes into contact with the outer peripheral surface of the heating roller 34, and detects the surface temperature of the fixing belt 31. Based on the detection result, the control unit 100 turns on and off the power supplied to the heater unit 341 to control the fixing belt 31 to reach the target temperature.

[0072] (2-2) Alignment adjustment mechanism (2-2-1) Principle of Fixing Belt Misalignment Correction As explained in Figure 12, when the elastic layer of the pressure roller is made of a sponge-like elastic material, the heat insulation properties are improved, but when it is compressed and deformed, a force is generated that moves the fixing belt in the axial direction, causing the position of the fixing belt to become biased in the axial direction.

[0073] 3(a) and (b) are schematic diagrams of the fixing unit 30 in FIG. 2 as viewed from the right. In order to make it easier to understand the operation of the pressure roller 32, the roller portion of the sponge-like elastic layer (hereinafter referred to as the "sponge roller portion") is shown painted black.

[0074] When pressure roller 32 is pressed against fixing belt 31 to form a nip portion, the sponge roller portion is compressed in the nip portion so as to tilt toward one axial direction due to the anisotropy of the cell structure (see FIG. 12(b)).

[0075] In order to correct such a bias of the fixing belt 31, in this embodiment, the rotation axis 321 of the pressure roller 32, which is the drive roller, is inclined, and the alignment is adjusted so that the inclination of the conveying force applied from the pressure roller 32 to the fixing belt 31 is in the direction that corrects the bias of the fixing belt 31.

[0076] When the compressive deformation of the sponge roller portion of the pressure roller 32 generates a force that moves the fixing belt 31 in the X1 direction, the right side of the pressure roller 32 is raised slightly as shown in Figure 3(b), and the pressure roller 32 is tilted relative to the longitudinal direction (horizontal direction) of the support pad 33 (tilt angle θ).

[0077] As a result, the conveying force f applied by the pressure roller 32 to the fixing belt 31 at the nip portion is tilted slightly to the left with respect to the rotational running direction of the fixing belt 31, so that the axial component force f2 (= f × sin θ) acts in the direction opposite to the movement direction X1 of the pressure roller 32.

[0078] Since the pressure roller 32 is also a drive roller that directly applies a rotational running force to the fixing belt 31, the axial component force f2 of the conveying force f is also sufficient to correct the deviation of the fixing belt 31 caused by the compressive deformation of the sponge roller portion, thereby effectively correcting the deviation of the fixing belt 31.

[0079] (2-2-2) Specific configuration of alignment adjustment mechanism 4 is a perspective view showing a specific configuration of an alignment adjustment mechanism 300 that controls the amount of inclination of the pressure roller 32 in the fixing unit 30 to correct the deviation of the fixing belt 31. Note that other elements such as the fixing belt 31, the support pad 33, and the heating roller 34 are not shown in the figure.

[0080] This alignment adjustment mechanism 300 consists of a bearing portion 310 that holds the pressure roller 32 so that it can tilt and move axially, and a tilting mechanism (conversion mechanism) 320 that tilts the axial movement of the pressure roller 32 in a direction that corrects the bias of the fixing belt 31.

[0081] At an initial stage when there is no misalignment in the fixing belt 31, the pressure roller 32 and the heating roller 34 are parallel, and the end (first end 321a) of the rotation shaft 321 of the pressure roller 32 at the rear left side in Figure 4 is held axially movable by a spherical plain bearing 332 attached to the first frame 331.

[0082] Further, the right front end (second end 321b) of the rotation shaft 321 of the pressure roller 32 is held by a spherical plain bearing 312 attached to a slide member 313 of the second frame 311 so as to be movable in the axial direction.

[0083] 7, in this embodiment, the sliding member 313 is formed by sandwiching a spacer 313c having the same width as the horizontal width of the elongated hole 314 formed in the second frame 311 between a front plate 313a and a rear plate 313b, and fixing them together with screws (not shown). This allows the sliding member 313 to be held slidably in the longitudinal direction (Z-axis direction) of the elongated hole 314 of the second frame 311.

[0084] Since the spherical plain bearings 332, 312 allow the shaft they hold to oscillate within a certain range of angles, the pressure roller 32 is held by the bearing part 310 so that it can move in the axial direction and can tilt within a plane parallel to the XZ plane, centered on the part held by the spherical plain bearing 332.

[0085] First frame 331 and second frame 311 of bearing portion 310 are urged by a urging mechanism (not shown) toward fixing belt 31 (in the present embodiment, a direction parallel to the Y axis) with a force F1 (FIG. 4), thereby forming a nip portion between pressure roller 32 and fixing belt 31. The configuration of the urging mechanism for pressing pressure roller 32 against fixing belt 31 is not particularly limited in the present invention, and a known mechanism may be used.

[0086] On the other hand, the tilting mechanism 320 converts the force that moves the pressure roller 32 in the axial direction due to the reaction force from the fixing belt 31 into a force (tilting force) that tilts the pressure roller 32. In this embodiment, a drive transmission unit consisting of a tapered gear 322 attached to the second end 321b of the rotation shaft 321 of the pressure roller 32 and a tapered gear 323 attached to a drive shaft 324 driven by motor M2 and meshing with the tapered gear 322 is configured to simultaneously function as the tilting mechanism 320.

[0087] 5(a) and (b) are diagrams for explaining the operation of adjusting the alignment of the pressure roller 32 by the tilting mechanism 320. FIG.

[0088] As shown in FIG. 5(a), when the pressure roller 32 is pressed against the fixing belt 31 to form a nip portion, the sponge roller portion in the nip portion is compressed and deformed so as to tilt in the axial direction due to the anisotropy of the cell structure, and in this example, a force is generated that tends to move the fixing belt 31 to the right in the figure (X1 direction).

[0089] The fixing belt 31 is stretched with a predetermined tension between the heating roller 34 and the support pad 33, and also has friction with the surface of the support pad 33, so that the fixing belt 31 does not move instantly in response to the moving force of the pressure roller 32, but moves gradually in the X1 direction while offering a certain resistance.

[0090] At that time, the pressure roller 32 receives a reaction force (moving force) from the fixing belt 31 in the -X1 direction. However, as described above, the pressure roller 32 is axially supported by the bearing portion 310 so as to be movable in the axial direction, and therefore the pressure roller 32 itself moves a predetermined amount in the -X1 direction.

[0091] Then, as shown in FIG. 5(b), the tapered gear 322 also moves in the -X1 direction together with the pressure roller 32, and due to the taper action between the tapered gears 322 and 323, they mesh with each other at the larger diameter parts, and a force (tilting force) is generated that pushes up the right end part of the rotating shaft 321 of the pressure roller 32, which is tiltably supported by the bearing part 310, in the Z1 direction, tilting the rotating shaft 321, and the entire pressure roller 32 tilts slightly upward to the right.

[0092] As a result, as explained in Figure 3(b), the vector of the conveying force f applied from the pressure roller 32 to the fixing belt 31 at the nip portion is tilted slightly to the left, and a component force f2 is generated that tries to return the fixing belt 31 to the -X1 direction, gradually correcting the bias of the pressure roller 32 in the X1 direction.

[0093] When this component force f2 becomes equal to the moving force applied to the fixing belt 31 by the elastic compression of the elastic layer 32a of the pressure roller 32 at the nip portion, the axial displacement amount of the fixing belt 31 and the tilt amount of the pressure roller 32 are balanced and stabilized, so that no further deviation occurs in the fixing belt 31. Also, the rotation shaft 321 does not move any further. In this sense, it can be said that the axial movement of the rotation shaft 321 is regulated by the tilt mechanism 320.

[0094] In Figures 5(a) and (b), the amount of tilt of the pressure roller 32 is shown somewhat exaggerated in order to explain the operating principle of the present disclosure; however, in reality, for example, the tilt is such that one end of the pressure roller 32 moves up and down by about 1 to 3 mm relative to a roller length of 400 mm, so that the nip pressure and nip width at the nip portion do not fluctuate significantly in the longitudinal direction (towards the rotation axis 321), and fixing quality is not degraded.

[0095] It should be noted that the direction of anisotropy of the cell structure of the elastic layer 32a is not completely uniform around the entire circumference of the roll-shaped elastic layer 32a, and the moving force applied to the fixing belt 31 due to the compressive deformation when entering the nip portion is not necessarily uniform. However, according to this configuration, the amount of tilt of the pressure roller 32 changes accordingly, and the equilibrium state is autonomously maintained.

[0096] FIG. 6 shows the operation of the alignment adjustment mechanism when the main direction of the anisotropy of the cell configuration in the elastic layer 32a of the pressure roller 32 is opposite to that in FIG. 5(a).

[0097] In this case, a moving force is applied to the fixing belt 31 in the -X1 direction due to the compressive deformation of the elastic layer 32a in the nip portion, and the pressure roller 32 receives the reaction force and moves in the X1 direction.

[0098] 6, the tapered gears 322 and 323 mesh with each other at their small diameter portions due to the taper action, and the pressure roller 32 tilts so that the right end of the rotation shaft 321 drops. As a result, the direction of the conveying force f applied to the fixing belt 31 by the pressure roller 32 also tilts to the right, so that a component force f2 acts to pull the fixing belt 31 back in the X1 direction, and eventually the moving force in the -X1 direction due to the compression of the elastic layer applied to the fixing belt 31 and the restoring force in the X1 direction caused by the tilt of the pressure roller 32 reach an equilibrium state, and the running state of the fixing belt 31 becomes stable.

[0099] When the above-mentioned equilibrium state is reached, the axial movement of the rotating shaft 321 should stop. However, since the rotating shaft 321 may move excessively, it is desirable to provide a regulating member that regulates the amount of axial movement of the rotating shaft 321 to prevent this.

[0100] In particular, even if the alignment is adjusted by converting the axial moving force of the rotating shaft 321 of the pressure roller 32 into a tilting force that tilts the pressure roller 32 as described above, it would be meaningless if the movement of the rotating shaft 321 made it impossible to ensure a good meshing state between the tapered gears 322 and 323 and made it impossible to transmit sufficient driving force, and therefore, from this perspective, in this embodiment, a regulating member is provided that regulates the amount of movement of the rotating shaft 321 in the axial direction.

[0101] FIG. 7 is a schematic side view showing the state of a bearing portion on the second end 321b side of the rotating shaft 321. As shown in FIG.

[0102] As shown in the figure, position regulating members 3211, 3212 are provided on either side of spherical plain bearing 312 attached to slide member 313 on rotating shaft 321, and regulate tapered gears 322 and 323 so that a certain meshing width (tooth width of the meshing portions of the two gears) W is maintained regardless of whether rotating shaft 321 moves in the X1 or -X1 direction.

[0103] It is desirable that the size of this width W be large enough to transmit power with sufficient durability without damaging the tapered gears 322 and 323, and specifically, it is determined by the rotational torque required to rotate the pressure roller 32, the shape and material of the gear teeth, etc.

[0104] The position restriction members 3211 and 3212 may be, for example, an E-ring fitted into a ring-shaped groove provided in the rotating shaft 321.

[0105] In order to correct the deviation of the fixing belt 31 within such a restricted range of movement of the rotating shaft 321, the specifications of the tapered gears 322 and 323, such as their axial length (width) and taper angle, can be determined by experiment or the like.

[0106] Furthermore, even if, for any reason in the device design or due to space constraints, the amount of movement of rotating shaft 321 cannot be sufficiently secured and the amount of tilt of pressure roller 32 is insufficient, a force acts at least in the direction of correcting the bias of fixing belt 31, so that the force with which the edge of fixing belt 31 abuts against the bias regulation member of fixing belt 31, such as a conventional flange, is significantly reduced and the life of fixing belt 31 can be extended.

[0107] (3) Summary of Effects of the First Embodiment (A) According to this embodiment, the pressure roller itself is used as a drive roller that applies a conveying force to the fixing belt, and the alignment of the drive roller itself is adjusted. This is very effective because it can apply a large force to correct the bias of the fixing belt against the relatively large moving force on the fixing belt caused by the compressive deformation of the elastic layer of the pressure roller.

[0108] (i) In addition, by converting the axial moving force of the pressure roller caused by the reaction force from the fixing belt into a tilting motion of the pressure roller, autonomous alignment adjustment is possible. Therefore, there is no need for a photoelectric sensor, control system, drive motor, etc. for alignment adjustment as in Patent Document 3, and significant cost reduction is expected.

[0109] (c) Furthermore, by using a tapered gear in the power transmission section from the drive source to the rotating shaft of the pressure roller, the power transmission section itself can be used as the tilting mechanism, making the configuration extremely simple and enabling further cost reduction.

[0110] <Second embodiment> The second embodiment differs from the first embodiment only in the configuration of the alignment adjustment mechanism 300 in the fixing unit 30, and the following description will focus on this difference.

[0111] (1) Configuration of the alignment adjustment mechanism The alignment adjustment mechanism 300 of the second embodiment also comprises a bearing portion 310 that holds the pressure roller 32 tiltably, and a tilting mechanism 320 that tilts the axial movement of the pressure roller 32 in a direction that corrects the bias of the fixing belt 31, but the configuration of the tilting mechanism 320 in particular differs from that of the first embodiment.

[0112] 8(a) and (b) are partial perspective views showing the specific configuration of the alignment adjustment mechanism 300 of the pressure roller 32 in the fixing section 30 in this embodiment, and the same symbols as in FIG. 3 indicate the same components as in the first embodiment, so their explanations are omitted.

[0113] In this figure, the fixing belt 31, the support pad 33, the heating roller 34, etc. are also omitted.

[0114] As shown in FIG. 8( a ), in this embodiment, a coupling 330 is used as a drive transmission unit for transmitting the power of the drive source to the rotary shaft 321 .

[0115] Coupling 330 is attached to second end 321b of rotation shaft 321 of pressure roller 32 and comprises a first coupling member 326 having an engagement recess 327 in the shape of a regular triangular prism, and a second coupling member 328 in the shape of a regular triangular pyramid attached to drive shaft 324 of the drive source and inserted into the engagement recess 327.

[0116] As shown in FIG. 8(b), when the second coupling member 328 is inserted into and engaged with the engagement recess 327 of the first coupling member 326, the drive shaft 324 is rotated to transmit a driving force to the pressure roller 32.

[0117] Rotation shaft 321 of pressure roller 32 is held by bearing portion 310 so as to be movable in the axial direction (X direction) as in the first embodiment and tiltable within a plane parallel to the XZ plane, but in this embodiment, compression spring 315 is disposed between the bottom of slot 314 and slide member 313 to urge second end 321b side of rotation shaft 321 upward (Z direction: downstream side in the running direction of the fixing belt at the nip portion). Note that compression spring 315 may be replaced by other urging means such as a leaf spring, and the location of the urging means may be other than slot 314 as long as it urges second end 321b side upward.

[0118] 9(a) and (b) are schematic diagrams for explaining the operating principle by which the coupling 330, which is the drive transmission part, fulfills the function of the tilt mechanism 320 in this embodiment.

[0119] As shown in Figure 9(a), when the pressure roller 32 is not tilted, the rotation axis 321 and drive axis 324 of the pressure roller 32 are parallel to each other, and it is desirable that the position of the center line of the drive axis 324 is shifted a distance d in the -Z direction (upstream in the running direction of the fixing belt 31) from the position of the center line of the rotation axis 321.

[0120] The magnitude of this distance d is a size necessary for the side surface (tapered surface) of the second coupling member 328 to engage with the end portion on the -Z direction side of the engagement recess 327 of the first coupling member 326 so that the tilting movement due to the taper action can be performed smoothly within the assumed range of movement of the rotation shaft 321, and is specifically determined in advance by experiments, etc.

[0121] As shown in FIG. 9(a), when the pressure roller 32 is pressed against the fixing belt 31 to form a nip portion, the sponge roller portion in the nip portion is compressed so as to tilt in the axial direction due to the anisotropy of the cell structure, and in this example, the fixing belt 31 moves to the right of the figure (X1 direction).

[0122] At that time, the pressure roller 32 also receives a reaction force in the -X1 direction from the fixing belt 31 and moves in the -X1 direction, so that the engagement position between the engagement recess 327 of the first coupling member 326 and the second coupling member 328 shifts, as shown in FIG. 9(b).

[0123] Since the second coupling member 328 has a regular triangular pyramid shape, its side surfaces are tapered. Also, as shown in FIG. 8(a), the rotating shaft 321 is biased upward by a force F2 from the compression spring 315 in the second frame 311. Therefore, when the pressure roller 32 moves in the -X1 direction, the rotating shaft 321 of the pressure roller 32 tilts slightly upward to the right in the figure.

[0124] As a result, the vector of the conveying force f applied from the pressure roller 32 to the fixing belt 31 at the nip portion is tilted slightly to the left, generating a component force f2 that tries to return the fixing belt 31 to the -X1 direction, and the bias of the pressure roller 32 is gradually corrected.

[0125] When this component force f2 becomes equal to the moving force applied to the fixing belt 31 by elastic compression at the nip portion of the elastic layer 32a of the pressure roller 32, the axial movement amount of the fixing belt 31 and the tilting amount of the pressure roller 32 reach equilibrium and stabilize, and no further deviation of the fixing belt 31 occurs.

[0126] FIG. 10 shows the operation of the alignment adjustment mechanism when the direction of anisotropy of the cell configuration in the elastic layer 32a of the pressure roller 32 is opposite to that in FIG. 9(a).

[0127] In this case, a moving force is applied to the fixing belt 31 in the -X1 direction due to the compressive deformation of the elastic layer 32a in the nip portion, and the pressure roller 32 moves in the X1 direction as a reaction force.

[0128] Then, the engagement recess 327 of the first coupling member 326 engages with the part (where the taper width becomes wider) of the second coupling member 328 having the shape of a regular triangular truncated cone due to the taper effect, so that the pressure roller 32 tilts so that the right end of the rotation shaft 321 is slightly lowered. As a result, the direction of the conveying force applied to the fixing belt 31 by the pressure roller 32 also tilts to the right, so that a force pulling the fixing belt 31 back in the X1 direction acts, and eventually the forces applied to the fixing belt 31 in the -X1 direction and the X1 direction are balanced, resulting in an equilibrium state and stabilizing the running state of the fixing belt 31.

[0129] In addition, in Figures 9(a)(b) and 10, the amount of tilt of pressure roller 32 is shown slightly exaggerated in order to explain the operating principle of the second embodiment. However, in reality, as in the first embodiment, for example, with respect to the roller length of pressure roller 32 being 400 mm, the tilt is only such that one end of pressure roller 32 moves up and down by only about 1 to 3 mm, so that the nip pressure and nip width at the nip portion do not fluctuate significantly in the longitudinal direction (towards rotation axis 321), and fixing quality is not deteriorated.

[0130] 9(a)(b) and 10, the engagement between the engagement recess 327 of the first coupling member 326 of the coupling 330 and the second coupling member 328 due to the axial movement of the rotating shaft 321 is also shown in an exaggerated manner in which the pressure roller 32 tilts due to the taper action in response to the axial displacement. As a result, it appears as if there is a gap between the upper part of the engagement recess 327 and the engagement recess of the first coupling member 326 and that there is no contact. However, in reality, the contact pressure between the lower part of the second coupling member 328 and the first coupling member 326 is the greatest due to the biasing force of the compression spring 315, and the other surfaces of the second coupling member 328 are maintained in contact with the engagement recess 327 of the first coupling member 326 even if the rotating shaft 321 tilts slightly, and this has been verified by the present inventors to not cause any hindrance to the transmission of driving force by the coupling 330.

[0131] In addition, the shape of the engaging recess 327 and the second coupling member in the coupling 330 is not limited to a regular triangular pyramid, but may be a regular polygonal pyramid having a regular quadrangular or higher pyramid. Needless to say, the shape of the engaging recess 327 of the first coupling member 326 is changed accordingly.

[0132] Also, even if the engaging recess 327 of the first coupling member 326 is formed into a regular triangular pyramid-shaped recess that opens toward the opening, and the second coupling member 328 is formed into a regular triangular prism-shaped recess, it is possible to tilt the rotating shaft 321 according to the amount of axial movement of the rotating shaft 321. Also, both the engaging recess 327 of the first coupling member 326 and the second coupling member 328 may be formed into a regular triangular prism-shaped recess.

[0133] In short, as long as the engagement surface of at least one of the engagement recess 327 of the first coupling member 326 and the second coupling member 328 has a tapered surface that forms an angle with respect to the axis, it can function as a tilting mechanism.

[0134] In the present embodiment as well, it is desirable to provide a regulating member for regulating the amount of axial movement of the rotating shaft 321, similar to the position regulating members 3211, 3212 (see FIG. 7) in the first embodiment, so that the first coupling member 326 and the second coupling member 328 can maintain the engagement relationship required for transmitting the driving force.

[0135] (2) Summary of Effects of the Second Embodiment In this embodiment, too, the pressure roller itself is used as a drive roller that applies a conveying force to the fixing belt, and the alignment of the drive roller itself is adjusted, so that a force sufficient to correct the deviation of the fixing belt caused by the compressive deformation of the elastic layer can be applied, and the deviation of the fixing belt can be effectively corrected.

[0136] In addition, the axial movement of the pressure roller can be used to adjust the alignment of the pressure roller autonomously, eliminating the need for photoelectric sensors, control systems, drive motors, etc., which is expected to result in significant cost reductions.

[0137] Furthermore, by configuring the coupling to have a tapered effect as the power transmission part from the drive source to the rotation shaft of the pressure roller, the power transmission part can also be used as the tilting mechanism, making the configuration extremely simple and contributing to further cost reduction.

[0138] <Modification> The above has been described based on the embodiments of the present disclosure, but it goes without saying that the present disclosure is not limited to the above-described embodiments, and the following modified examples are possible.

[0139] (1) In the fixing section 30 in the above embodiment, a nip portion is formed by sandwiching the fixing belt 31 between the support pad 33 and the pressure roller 32 (hereinafter, the member that sandwiches the fixing belt 31 to form the nip portion in this manner is also referred to as the “nip portion forming member”).

[0140] However, as shown in Fig. 11(a), a support roller 35 may be used as a support instead of the support pad 33 as a nip portion forming member. In this case, the support roller 35 is rotated by the pressure roller 32 via the fixing belt 31, so there is almost no problem of wear between the support roller 35 and the fixing belt 31. However, it goes without saying that it is desirable to use a material with as good heat insulating properties as possible as the material for the support roller 35.

[0141] In some cases, as shown in FIG. 11(b), a sponge-like elastic layer 36a may be provided on the support roller 36, and a conventional solid-type elastic layer may be formed on the pressure roller 37 to drive it.

[0142] However, in this case, it is understood that the direction of deviation of the fixing belt 31 due to the compressive deformation of the sponge-like elastic layer 36a of the support roller 36 and the direction of axial movement of the pressure roller 37 are the same, so it is necessary to change the inclination of the taper so that the tilting direction of the rotating shaft 321 by the tilting mechanism 320 is opposite to that in the above embodiment, or to provide the tilting mechanism 320 on the first end 321a side.

[0143] Furthermore, it is also possible to adopt a configuration in which a sponge-like elastic layer is provided on both the pressure roller 32 and the support roller (support) 36. When the moving forces applied to the fixing belt 31 due to the compressive deformation of the elastic layer of the pressure roller 32 and the elastic layer of the support roller 36 are in opposite directions, the fixing belt 31 is biased in the direction of the larger moving force, and therefore the tilting mechanism 320 is set to tilt the rotation shaft 321 to correct this.

[0144] (2) In the above embodiment, the pressure roller 32 is configured to be tiltable within a plane parallel to the plane including the support surface 33a of the support pad 33 that contacts the fixing belt 31 (the XZ plane in the figure).

[0145] As a result, even when the pressure roller 32, which is the driving roller, is tilted, the nip pressure with the fixing belt 31 is maintained, and the pressure roller 32, which is the driving roller, can effectively apply a force (component force f2) to the fixing belt 31 to correct the bias of the fixing belt 31.

[0146] However, the tilting direction of the pressure roller 32 by the tilting mechanism 320 is not limited to this, and as long as the pressure roller 32 is tiltable within a plane that is parallel to the longitudinal direction (X-axis direction) of the support pad 33 and parallel to a plane that includes at least a part of the nip portion formed between the pressure roller 32 and the fixing belt 31, it is possible to apply a force to the fixing belt 31 to correct the bias of the fixing belt 31.

[0147] Moreover, the pressure roller 32 may be tilted in a plane that is parallel to the longitudinal direction of the support pad 33 and perpendicular to the force F1 (FIG. 4) that biases the pressure roller 32 toward the fixing belt 31 as viewed from the axial direction. Since the compressive deformation of the elastic layer 32a in the portion that receives the pressing force F1 perpendicularly is the largest and the nip pressure is also large, it is considered that the effect of correcting the deviation obtained by adjusting the alignment by tilting the pressure roller 32 in the above-mentioned plane is also large.

[0148] Furthermore, if it is possible to ensure a nip pressure in the longitudinal direction of the nip portion within a range that does not significantly affect the fixing accuracy, it is also possible to consider a configuration in which the nip is tilted in a direction that is not parallel to the longitudinal direction (for example, the Y-axis direction in FIG. 3). In this case, a moving force acts on fixing belt 31 in the axial direction from the part with higher nip pressure to the part with lower nip pressure, and rotating shaft 321 moves in response to the reaction force, so the taper direction in tilting mechanism 320 is set so that the amount of movement corrects the deviation of fixing belt 31.

[0149] Even in such a case, it is possible to apply a force to the fixing belt 31 to suppress the deviation.

[0150] (3) In the above-described first embodiment, the tapered gear 323 of the drive shaft 324 is disposed upstream of the tapered gear 322 attached to the rotating shaft 321 of the pressure roller 32 in the running direction of the fixing belt 31 at the nip portion (see FIG. 5(a)). However, when the taper directions of the tapered gears 322 and 323 are opposite to each other, the tapered gear 323 is disposed downstream of the tapered gear 322 in the running direction of the fixing belt 31.

[0151] In the latter case, it is preferable to provide a biasing means such as a spring to bias the right end of the rotating shaft 321 (the side to which the tapered gear 322 is attached) toward the tapered gear 323. This is because the right end of the pressure roller 32 drops downward due to its own weight, causing the tapered gear 322 to move away from the tapered gear 323, preventing a good meshing state between the two gears and preventing smooth power transmission and tilting operation.

[0152] However, even in the case of the first embodiment, the right end portion of the rotating shaft 321 may be biased downward to further improve the meshing state between the tapered gears 322 and 323.

[0153] To summarize this modified example (3), the shaft (rotation shaft) of the driving roller (pressure roller 32) Transfer It can be expressed as "the rotating shaft 321 is provided with a biasing means for biasing the second gear (tapered gear 322) and the first gear (tapered gear 323) within the tilting plane so as to ensure meshing between the second gear (tapered gear 322) and the first gear (tapered gear 323)."

[0154] (4) In the above embodiment, the rotating shaft 321 of the pressure roller 32 is supported in the bearing portion 310 by the spherical plain bearing 332 and the spherical plain bearing 312 so that the pressure roller 32 can move axially and tilt. However, a pivot bearing or the like can also be used as a bearing (swinging bearing) that supports the rotating shaft so that it can be swayed in this manner.

[0155] Furthermore, if the tilt angle is not too large, the tilting movement of the rotating shaft 321 may be permitted by the "play" that is normally present in, for example, a ball bearing, and it is not impossible to tilt the first frame 331 and the second frame 311 as a single unit, so it is not necessarily essential to use a rocking bearing to hold the rotating shaft 321 in a tiltable manner.

[0156] (5) In the above first embodiment, the tilting mechanism 320 is constructed by using the tapered gear 323 (first gear) and the tapered gear 322 (second gear) as the drive transmission part. However, if only one of the gears is a tapered gear, it can function as the tilting mechanism 320.

[0157] (6) In a configuration using coupling 330 as in the second embodiment described above, the second coupling member 328 may be attached to the rotating shaft 321 of the pressure roller 32, and the first coupling member 326 having the engagement recess 327 may be attached to the drive shaft 324 side.

[0158] (7) In the fixing section 30 in the above embodiment, the heating roller 34 having a built-in halogen heater is used as the heat source, but the present invention is not limited to this and may be configured to heat the fixing belt 31 by electromagnetic induction, or may be a fixing device configured to directly pass electricity through the fixing belt 31 to generate resistance heat.

[0159] <Supplementary Information> Although the fixing device and image forming apparatus according to the present invention have been described above based on the embodiment and modified examples, the present invention is not limited to the above embodiment and modified examples. The present invention also includes forms obtained by applying various modifications to the above embodiment and modified examples that a person skilled in the art can think of, and forms realized by arbitrarily combining the components and functions of the embodiment and modified examples within the scope of the present invention. [Industrial Applicability]

[0160] The present disclosure can be widely applied to image forming apparatuses having a fixing device that thermally fixes an unfixed toner image formed on a sheet using a fixing belt. [Explanation of symbols]

[0161] 1. Printer 30 Fixing section 31 Fixing belt 32 Pressure roller 33 Support Pad 34 Heating roller 300 Alignment adjustment mechanism 310 Bearing section 312, 332 Spherical plain bearing 313 Slide member 314 Slot 320 Tilting mechanism (conversion mechanism) 321 Rotational Axis 322, 323 Tapered gear 324 Drive shaft 330 Coupling 326 First coupling member 328 Second coupling member 3211, 3212 Position control member Np Nip

Claims

1. A fixing device in which a fixing belt is pressed and sandwiched between a long-sized support and a drive roller to form a nip portion, the drive roller is driven to run the fixing belt, and a sheet having an unfixed image formed thereon is passed through the nip portion to fix the image, At least one of the support and the driving roller is provided with a sponge-like elastic layer, a bearing portion that holds the shaft of the drive roller so as to be axially movable and tiltable; a conversion mechanism for converting the axial moving force of the drive roller into a tilting force for tilting the axis of the drive roller in a direction for correcting the deviation of the fixing belt; A fixing device comprising:

2. a drive transmission unit that transmits a driving force of a drive shaft of a drive source to a shaft of the drive roller; The drive transmission unit has the function of the conversion mechanism.

2. The fixing device according to claim 1,

3. the drive transmission unit includes a first gear attached to a drive shaft of the drive source, and a second gear attached to a shaft of the drive roller and meshing with the first gear, At least one of the first gear and the second gear is a tapered gear, thereby providing the function of the conversion mechanism.

3. The fixing device according to claim 2,

4. The drive roller has a restricting means for restricting a range of movement in the axial direction.

4. The fixing device according to claim 3.

5. The regulating means regulates the axial movement range of the drive roller so that the meshing tooth width between the first gear and the second gear does not become equal to or smaller than a certain width.

5. The fixing device according to claim 4.

6. The second gear is disposed on the upstream side or the downstream side of the first gear in the running direction of the fixing belt in the nip portion.

6. The fixing device according to claim 3, wherein the fixing member is a fixing member having a fixing roller.

7. the drive transmission unit includes a first coupling member attached to one of the drive shaft of the drive source and the shaft of the drive roller and having an engagement recess, and a second coupling member attached to the other shaft and inserted into the engagement recess of the first coupling member to engage with the recess, The coupling surface of at least one of the first and second coupling members is tapered at an angle to the direction of the shaft to which it is attached, thereby providing the function of the conversion mechanism.

3. The fixing device according to claim 2,

8. The axis of the drive shaft of the drive source is shifted upstream in the running direction of the fixing belt with respect to the axis of the drive roller.

8. The fixing device according to claim 7,

9. The fixing belt is fixed to the fixing member by a fixing member that is provided on the fixing member.

9. The fixing device according to claim 7, wherein the fixing member is a fixing member having a fixing roller.

10. The drive roller has a restricting means for restricting a range of movement in the axial direction.

10. The fixing device according to claim 7, wherein the fixing member is a fixing member having a fixing roller.

11. The conversion mechanism tilts the driving roller within a plane that is parallel to a longitudinal direction of the support and is parallel to a plane that includes at least a part of a nip portion formed when the driving roller is pressed against the fixing belt. The fixing device according to any one of claims 1 to 10.

12. An image forming apparatus including an image forming unit that forms an unfixed image on a sheet, and a fixing unit that thermally fixes the unfixed image on the sheet, 12. An image forming apparatus, comprising the fixing device according to claim 1 as the fixing section.

Images