JP2014044364A - Fixing device and image forming apparatus including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device that suppresses meandering of a belt caused by a pressing member such as a fixing roller and a pressure roller to reduce damage due to a load placed on a fixing belt, and an image forming apparatus including the fixing device.SOLUTION: A fixing device 5 includes a fixing roller 23 and a suspension roller 27 that have a fixing belt 26 suspended thereon, and a belt support unit 45 that supports the fixing roller 23 and the suspension roller 27. The belt support unit 45 includes: a bearing hole 45f (support part) that is provided on one end part in a longitudinal direction (A direction) of the belt support unit 45, and rotatably supports the belt support unit 45 with respect to a device body 5a; and a circular-arc hole 45g (position adjustment part) that is provided on the other end part in the longitudinal direction of the belt support unit 45, adjusts inclination of the belt support unit 45 with respect to an axial direction of a pressure roller 19 with the bearing hole 45f as the center, and is fixed to the device body 5a.

Description

  The present invention relates to a fixing device used for a copying machine, a printer, a facsimile, a composite machine thereof, and the like, and an image forming apparatus including the fixing device, and more particularly, to a fixing device that restricts meandering of a fixing belt and an image forming apparatus including the fixing device. Is.

  Conventionally, in an image forming apparatus, a toner image formed on an image carrier such as a photosensitive drum is transferred to a recording medium, and the recording medium carrying the toner image is conveyed toward a fixing device. The toner image on the recording medium is fixed on the recording medium by applying heat and pressure. The fixing device includes a fixing belt that is rotatably suspended between the fixing roller and the suspension roller, and a pressure roller that is pressed against the fixing belt, and the recording medium is disposed between the fixing belt and the pressure roller. There is a belt fixing method in which a toner image is fixed on a recording medium while passing through the nip portion.

  In the fixing device of the belt fixing type, when the fixing belt suspended between the rollers is rotated, the fixing belt may move in the roller axis direction on the roller and meander. When the fixing belt meanders, there arises a problem that the fixing of the toner image on the recording medium is shifted, and when the fixing belt meanders, the fixing belt edge is damaged. There was a fear.

  Therefore, a technique for suppressing the meandering of the fixing belt is conventionally known. For example, a fixing device described in Patent Document 1 includes a fixing belt suspended on a driving roller and a meandering correction roller, a meandering detection sensor that detects the meandering of the fixing belt by contacting an edge of the fixing belt, and a meandering correction roller. And a meandering correction cam that rotates by driving the motor and a clutch that rotates the motor according to the detection result of the meandering detection sensor. When the meandering detection sensor detects meandering of the fixing belt, the clutch is turned on, and the rotational force of the motor is transmitted to the meandering correction cam. As a result, the meandering correction cam begins to rotate, and the meandering correction roller swings in a direction to correct the meandering of the fixing belt.

  In addition, the fixing device described in Patent Document 2 is configured to meander a fixing belt suspended between a fixing roller and a suspension roller, and a fixing belt provided on both sides of a shaft end portion of the suspension roller and movable in the roller axial direction. A belt deviation detecting means for detecting, a supporting means for supporting the shaft end portion of the suspension roller so as to be displaceable in a direction perpendicular to the axial direction, and when the fixing belt moves in the axial direction via the belt deviation detecting means. And conversion means for converting the displacement of the shaft end portion of the suspension roller into a displacement perpendicular to the axial direction. In this configuration, when the belt meandering occurs and the fixing belt moves in the meandering direction, the belt deviation detecting means rotating together with the suspension roller is pushed by the edge of the fixing belt, and in the meandering direction of the fixing belt. Moving. As the belt deviation detecting means moves in the meandering direction, the supporting means is displaced in the direction perpendicular to the meandering direction (axial direction) by the converting means, and the suspension roller also moves in the direction perpendicular to the axial direction together with the supporting means. At this time, a force in the direction of reducing the meandering acts on the fixing belt to prevent the meandering of the belt.

JP-A-5-297953 (paragraphs [0013] to [0022], FIGS. 1 and 3) JP 11-65336 A (paragraphs [0038] to [0045], FIGS. 1 and 3)

  However, the fixing device described in Patent Document 1 includes a detection sensor, a motor, a clutch, and a meandering correction mechanism for correcting the meandering of the fixing belt, and the device becomes complicated and expensive.

  Further, in the fixing device described in Patent Document 2, the conversion unit is configured by a plate cam member having an inclined surface that contacts the guide member of the belt deviation detection unit and converts the displacement in the meandering direction into the displacement in the perpendicular direction. Further, the support means is a length for fitting a spring that urges the guide member so as to always contact the plate cam member and a shaft end portion of the suspension roller that is movable in a direction perpendicular to the axial direction (meandering direction). It is comprised with the side plate which has a hole. In such a configuration, the load applied to the fixing belt fluctuates at the start or end of driving of the fixing belt, and if the load applied to the fixing belt fluctuates, the position of the suspension roller becomes unstable in the long hole of the side plate. Become. Further, since the plate cam member and the guide member are in a single contact due to the bias of the spring, it is difficult to smoothly convert the axial displacement of the shaft end portion of the suspension roller into a displacement perpendicular to the axial direction.

  In the fixing devices described in Patent Documents 1 and 2, meandering correction mechanisms are provided on at least one of the fixing roller and the suspension roller, and the meandering of the fixing belt is suppressed by the meandering correction mechanism. However, the meandering of the fixing belt does not occur only between the fixing roller and the suspension roller that suspends the fixing belt, but the inclination of the mutual axes of the pressure roller and the fixing roller that press against each other via the fixing belt, It also occurs in the fixing nip portion due to variations in accuracy of the cylindrical shape of the pressure roller and the fixing roller, balance of the pressing force in the longitudinal direction of the fixing nip portion, and the like. In the belt fixing method, a fixing belt is suspended between a pressing pad fixed to the apparatus main body and a belt holding unit, and the pressing pad and the pressure roller are pressed through the fixing belt. The meandering of the belt in the fixing nip is not limited to the case where the fixing belt is suspended between the rollers, but also in the case where the fixing belt is suspended by a pressure pad, the mutual inclination of the pressure roller and the pressure pad, This also occurs due to variations in the accuracy of the cylindrical shape, the balance of the pressing force in the longitudinal direction of the fixing nip portion, and the like.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a fixing device that reduces damage caused by a load applied to a fixing belt by suppressing belt meandering by a pressing member such as a fixing roller and a pressure roller, and an image forming apparatus including the fixing device. To do.

  In order to achieve the above object, a first invention includes an endless fixing belt heated by a heating means, a pressure roller disposed opposite to an outer peripheral surface of the fixing belt, and an inner periphery of the fixing belt. A pressing member that is disposed opposite to the surface and presses against the pressure roller via the fixing belt; and a suspension member that is disposed opposite to the inner peripheral surface of the fixing belt so as to be able to circulate the fixing belt together with the pressing member. An unfixed toner on the recording medium when the recording medium passes through a nip portion between the fixing belt and the pressure roller, and a suspension support member, and a belt support unit that supports the pressing member and the suspension member. In the fixing device for fusing and fixing an image, the belt support unit is provided at one end in a direction orthogonal to the traveling direction of the fixing belt, and the belt support unit is attached to the apparatus main body. A support portion that is rotatably supported and an other end portion in a direction orthogonal to the traveling direction of the fixing belt, and the inclination of the belt support unit with respect to the axial direction of the pressure roller is adjusted around the support portion. And a position adjusting unit fixed to the apparatus main body.

  According to the first invention, when the belt support unit is attached to the apparatus main body, the position adjustment unit adjusts the inclination of the belt support unit with respect to the rotation axis of the pressure roller, thereby causing the pressure roller to cause belt meandering and The inclination and the like of the pressing members are adjusted. By fixing the belt support unit to the apparatus main body in the position adjustment unit after adjustment, when the fixing belt circulates, belt meandering between the pressure roller and the pressing member is suppressed, and the fixing belt cracks due to belt meandering Damage such as breakage is reduced.

1 is a diagram illustrating an overall configuration of an image forming apparatus including a fixing device according to a first embodiment of the present invention. Side surface sectional drawing which shows the structure of the fixing device which concerns on 1st Embodiment. Plan sectional drawing which shows the suspension roller periphery of the fixing device which concerns on 1st Embodiment. 1 is a perspective view illustrating a configuration of a belt support unit of a fixing device according to a first embodiment. The top view which shows the belt support unit which concerns on 1st Embodiment. Sectional drawing which shows the state which attached the belt support unit which concerns on 1st Embodiment to the apparatus main body. Side surface sectional drawing which shows the structure of the fixing device which concerns on 2nd Embodiment of this invention. Plan sectional drawing which shows the structure of the belt support unit of the fixing device which concerns on 2nd Embodiment.

  Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited to these embodiments. Further, the use of the invention and the terms shown here are not limited thereto.

(First embodiment)
FIG. 1 is a diagram illustrating a configuration of an image forming apparatus including a fixing device according to an embodiment of the present invention. The image forming apparatus 1 includes a sheet feeding unit 2 disposed in a lower portion thereof, a sheet conveying unit 3 disposed on a side of the sheet feeding unit 2, and an image forming unit disposed above the sheet conveying unit 3. The image forming unit 4, the fixing device 5 disposed on the discharge side in the paper conveyance direction from the image forming unit 4, and the image reading unit 6 disposed above the image forming unit 4 and the fixing device 5. .

  The paper feed unit 2 includes a plurality of paper feed cassettes 7 that store paper 9 that is a recording medium. The paper 9 is sent to the paper transport unit 3 one by one.

  The paper 9 sent to the paper transport unit 3 is transported toward the image forming unit 4 via a paper transport path 10 provided in the paper transport unit 3. The image forming unit 4 forms a toner image on the paper 9 by an electrophotographic process. The photosensitive member 11 is supported so as to be rotatable in the direction of the arrow in FIG. A charging unit 12, an exposure unit 13, a developing unit 14, a transfer unit 15, a cleaning unit 16, and a charge eliminating unit 17 are provided.

  The charging unit 12 includes a charging wire to which a high voltage is applied. When a predetermined potential is applied to the surface of the photoconductor 11 by corona discharge from the charging wire, the surface of the photoconductor 11 is uniformly charged. Then, when light based on the image data of the original read by the image reading unit 6 is irradiated to the photoconductor 11 by the exposure unit 13, the surface potential of the photoconductor 11 is selectively attenuated, and the surface of the photoconductor 11 is irradiated. An electrostatic latent image is formed.

  The developing unit 14 develops the electrostatic latent image on the surface of the photoconductor 11, and a toner image is formed on the surface of the photoconductor 11. This toner image is transferred by the transfer unit 15 to the sheet 9 supplied between the photoconductor 11 and the transfer unit 15.

  The sheet 9 on which the toner image has been transferred is conveyed toward the fixing device 5 disposed downstream of the image forming unit 4 in the sheet conveying direction. In the fixing device 5, the paper 9 is heated and pressurized, and the toner image is melted and fixed on the paper 9. Next, the sheet 9 on which the toner image is fixed is discharged onto the discharge tray 21 by the discharge roller pair 20.

  After the transfer of the toner image onto the paper 9 by the transfer unit 15, the toner remaining on the surface of the photoconductor 11 is removed by the cleaning unit 16, and the residual charge on the surface of the photoconductor 11 is removed by the charge eliminating unit 17. Then, the photosensitive member 11 is charged again by the charging unit 12, and image formation is performed in the same manner.

  The fixing device 5 is configured as shown in FIG. FIG. 2 is a side sectional view showing the configuration of the fixing device 5. In FIG. 2, a belt support unit to be described later is omitted.

  The fixing device 5 uses an electromagnetic induction heating method, and includes a heating unit 18 and a pressure roller 19. The heating unit 18 includes an endless fixing belt 26, a fixing roller 23 disposed on the inner periphery of the fixing belt 26, a suspension roller 27 that suspends the fixing belt 26 together with the fixing roller 23, and an outer periphery of the fixing belt 26. An induction heating unit 30 disposed opposite to the suspension roller 27. The fixing device 5 is supplied from the power source 41 based on the power source 41 connected to the induction heating unit 30, the thermistor 25 that detects the temperature of the outer peripheral surface of the fixing belt 26, and the detected temperature of the thermistor 25. And a control unit 43 that controls the current.

  The pressure roller 19 is driven to rotate in the direction of the arrow in FIG. 2 by a drive source (not shown) such as a motor, and further pressurizes the fixing roller 23 in the center direction. As a result, the pressure roller 19 and the fixing roller 23 as a pressing member are pressed through the fixing belt 26. In the pressing state of the pressure roller 19 and the fixing roller 23, the rotation of the pressure roller 19 causes the fixing belt 26 and the fixing roller 23 to rotate in the direction of the arrow in FIG. The suspension roller 27 that is a member is driven to rotate. A nip portion N is formed at a portion where the fixing belt 26 and the pressure roller 19 come into contact with each other while rotating in reverse. In this nip portion N, the sheet 9 is sandwiched, and the sandwiched sheet 9 is heated and pressed to melt and fix the powdery toner on the sheet 9.

  The pressure roller 19 includes a cylindrical cored bar 19a, an elastic layer 19b formed on the cored bar 19a, and a release layer 19c that covers the surface of the elastic layer 19b. For example, the pressure roller 19 is set to an outer diameter of 40 mm, has an elastic layer 19b made of silicone rubber having a thickness of 2 mm on an aluminum core 19a, and has a thickness of 30 μm made of a fluororesin tube or the like on the elastic layer 19b. The release layer 19c is provided.

  The fixing roller 23 is in pressure contact with the inner peripheral surface of the fixing belt 26 so as to be rotatable together with the fixing belt 26. For example, the fixing roller 23 has an outer diameter of 40 mm, and has an elastic layer 23 b made of silicone rubber having a thickness of 8 mm on the core metal 23 a. The elastic layer 23 b suspends the fixing belt 26.

  The suspension roller 27 is in pressure contact with the inner peripheral surface of the fixing belt 26 so as to be rotatable together with the fixing belt 26. For example, the suspension roller 27 is set to an outer diameter of 30 mm, and a Teflon (registered trademark) coating is applied on a cored bar made of carbon steel pipe.

  The fixing belt 26 is an endless heat-resistant belt having an outer diameter of 60 mm, for example, in a circular state, and is formed of, for example, an induction heating layer 26a of electroformed nickel having a thickness of 35 μm and a silicone rubber having a thickness of 300 μm in order from the inner peripheral side. The layer 26b is composed of a fluororesin tube having a thickness of 30 μm and a release layer 26c that improves the releasability when the unfixed toner image is melted and fixed at the nip N.

  The induction heating unit 30 includes an exciting coil 37, a bobbin 38, and a magnetic core 39, and heats the fixing belt 26 by electromagnetic induction. The induction heating unit 30 extends in the longitudinal direction (the front and back direction of the paper surface in FIG. 2) and is disposed to face the fixing belt 26 so as to surround substantially half of the outer periphery of the fixing belt 26.

  The exciting coil 37 is attached to the bobbin 38 by winding a litz wire in a loop shape a plurality of times, for example, eight turns, along the width direction of the fixing belt 26 (front and back direction in FIG. 2). The exciting coil 37 is connected to a power source 41 and generates an alternating magnetic flux by a high frequency current supplied from the power source 41. The magnetic flux from the exciting coil 37 passes through the magnetic core 39, is guided in a direction parallel to the paper surface of FIG. 2, and passes along the induction heating layer 26 a of the fixing belt 26. An eddy current is generated in the induction heat generation layer 26a due to a change in the alternating strength of the magnetic flux passing through the induction heat generation layer 26a. When an eddy current flows through the induction heating layer 26a, Joule heat is generated by the electrical resistance of the induction heating layer 26a, and the fixing belt 26 generates heat.

  When the fixing belt 26 is heated by the induction heating unit 30 that is a heating unit and rises to a predetermined temperature, the paper 9 sandwiched by the nip portion N is heated and is pressed by the pressure roller 19. The powdery toner on the paper 9 is melted and fixed on the paper 9. As described above, the fixing belt 26 is made of a thin material having good thermal conductivity and has a small heat capacity. Therefore, the fixing device 5 is activated in a short time, and image formation is started quickly.

  FIG. 3 is a plan sectional view showing the structure of the suspension roller 27 and its surroundings as seen from the upper side of FIG.

  The suspension roller 27 includes a rotation holding portion 27a and a restriction flange portion 27b that is a meandering restriction portion. The rotation holding portion 27a is cylindrical and holds the fixing belt 26, and suspends the fixing belt 26 together with the fixing roller 23 so as to be rotatable. The restriction flange portion 27b is provided to project annularly from the outer peripheral surface of the rotation holding portion 27a at both ends in the roller axial direction (A direction) of the rotation holding portion 27a, and by contacting the edge of the fixing belt 26 with each other. The meandering of the fixing belt 26 in the width direction (A direction) is restricted.

  The suspension roller 27 is fixed to the rotating shaft 51, and the rotating shaft 51 is rotatably supported by the belt support unit 45 at both ends.

  The belt support unit 45 includes the suspension roller 27, and includes bearings 45a and 45a that rotatably support the rotation shaft 51 of the suspension roller 27 at both ends in the axial direction. Further, the belt support unit 45 has flat surfaces 45 b and 45 b that abut against both axial end surfaces of the suspension roller 27 and position the suspension roller 27 in the axial direction.

  Therefore, when the fixing belt 26 rotates, the suspension roller 27 is driven to rotate while being axially positioned by the flat surfaces 45b and 45b and held by the bearings 45a and 45a. When the suspension roller 27 is driven to rotate and the rotation shaft 51 of the suspension roller 27 is inclined with respect to the rotation shaft of the fixing roller 23, the fixing belt 26 moves on the rotation holding portion 27 a of the suspension roller 27. It snakes in the direction of the roller axis, and one edge of the fixing belt 26 comes into contact with the restriction flange 27b of the suspension roller 27. As a result, the meandering of the fixing belt 26 is restricted.

  The belt support unit 45 includes the fixing roller 23 and the fixing belt 26 in addition to the suspension roller 27. A detailed configuration of the belt support unit 45 is shown in FIGS. 4 is a perspective view showing a configuration of a belt support unit 45 that supports the suspension roller 27 and the fixing roller 23, and FIG. 5 is a plan view of only the belt support unit 45 as viewed from the upper side of FIG. FIG. 6 is a cross-sectional view showing a state in which the belt support unit 45 is attached to the apparatus main body. In FIG. 4, the induction heating unit 30 is omitted.

  As shown in FIG. 4, the belt support unit 45 is formed in a rectangular parallelepiped box shape that is open at the top and bottom, and includes the fixing roller 23, the suspension roller 27, and the fixing belt 26. A suspension roller 27 is disposed on the upper side of the belt support unit 45, and the suspension roller 27 faces the induction heating unit 30 (not shown) through the fixing belt 26 at the upper opening. A fixing roller 23 is disposed below the belt support unit 45, and the fixing roller 23 faces the pressure roller 19 through the fixing belt 26 at the lower opening.

  As described above, the suspension roller 27 is rotatable on the side walls 45h and 45h formed on the rotation shaft 51 in the longitudinal direction of the belt support unit 45 (A direction, the direction orthogonal to the traveling direction of the fixing belt 26). Supported.

  Similar to the suspension roller 27, the fixing roller 23 is rotatably supported by the side walls 45 h and 45 h of the belt support unit 45. That is, the fixing roller 23 is fixed to the rotating shaft 52 protruding from both ends in the axial direction, and the rotating shaft 52 is rotatably supported by the bearing 45 c of the belt support unit 45. Further, the fixing roller 23 is brought into contact with the inner surfaces of the side walls 45h and 45h of the belt support unit 45, whereby the axial direction of the fixing roller 23 is positioned. Instead of the configuration in which the fixing roller 23 is fixed to the rotating shaft 52, the rotating shaft 52 may be fixed to the belt support unit 45 and the fixing roller 23 may rotate around the rotating shaft 52. Further, similarly to the alternative configuration of the fixing roller 23, instead of the configuration in which the suspension roller 27 is fixed to the rotation shaft 51, the rotation shaft 51 is fixed to the belt support unit 45, and the suspension roller 27 rotates around the rotation shaft 51. You may comprise.

  A first protrusion 45 d is formed on one side wall 45 h of the belt support unit 45, and a second protrusion 45 e is formed on the other side wall 45 h of the belt support unit 45. 45 d of 1st protrusion parts and the 2nd protrusion part 45e are comprised by the flat plate which protrudes from the side walls 45h and 45h to the outer side of a longitudinal direction between the bearings 45a and 45c of the side wall 45h, respectively.

  A support hole 45f as a support portion is formed in the first protrusion 45d. The support hole 45 f is fitted with a support shaft 47 that is fixed to the apparatus main body of the fixing device 5 and extends in the vertical direction, and can be rotated around the support shaft 47. Note that a configuration may be adopted in which a support shaft is formed in the first protrusion 45d, and a support hole in which the support shaft is fitted is provided in the apparatus main body.

  The second protrusion 45e is formed with an arc hole 45g (see also FIG. 5), which is a position adjusting portion. The circular arc hole 45g is a long hole extending on the circumference around the support shaft 47 (support hole 45f).

  As shown in FIG. 6, the screw 48 engages with the circular arc hole 45g, and the second protrusion 45e is fixed to the apparatus main body 5a by screwing the screw 48 into a screw hole formed at a predetermined position of the apparatus main body 5a. Is done.

  Before the belt support unit 45 is fixed to the apparatus main body 5a, the belt support unit 45 is tilt-adjusted with respect to the axial direction (direction A, see FIG. 4) of the rotation shaft 53 of the pressure roller 19 using the arc hole 45g. The By performing this adjustment, the belt meandering between the pressure roller 19 and the fixing roller 23 is suppressed when the fixing belt 26 circulates by rotation of the pressure roller 19.

  Specifically, in a state where the support hole 45f (see FIG. 4) of the belt support unit 45 is fitted to the support shaft 47 of the apparatus main body 5a, the belt support unit 45 is moved in the horizontal direction (the pressure roller 19 and the fixing roller 23). Oscillating (in the direction perpendicular to both the pressure contact direction (B direction in FIG. 4) and the axial direction (A direction in FIG. 4) of the pressure roller 19) The belt support unit 45 is held (adjusted) so that the inclination of the fixing roller 23 with respect to the axial direction (A direction) of the roller 19 is minimized. After this position adjustment, the belt support unit 45 is fixed to the apparatus main body 5a by inserting a screw 48 (see FIG. 6) through the circular arc hole 45g and screwing it into the screw hole of the apparatus main body 5a.

  As described above, the belt support unit 45 is swung horizontally, the inclination of the fixing roller 23 with respect to the axial direction of the pressure roller 19 is adjusted, and then the belt support unit 45 is attached to the apparatus main body 5a. Is circulated, the meandering of the fixing belt 26 between the pressure roller 19 and the fixing roller 23 is suppressed. As a result, damage such as cracks and breakage of the fixing belt 26 due to the belt meandering is reduced.

(Second Embodiment)
FIG. 7 is a side sectional view showing the configuration of the fixing device according to the second embodiment of the present invention, and FIG. 8 is a plan sectional view showing the configuration of the belt support unit according to the second embodiment. In the second embodiment, the fixing belt 26 is held by a pressing pad 60 that is a pressing member and a belt holding portion 59 that is a suspension member. In addition, the induction heating part 30 is abbreviate | omitted in FIG.

  As shown in FIG. 7, the fixing device 5 is a fixing method using electromagnetic induction heating, and includes a fixing belt 26, a pressure roller 19, an induction heating unit 30 that heats the fixing belt 26, and a temperature detection unit. A thermistor 25 and a belt support unit 55 are provided.

  The fixing belt 26 is an endless heat-resistant belt having an outer diameter of 30 to 50 mm in a circular state, and has a longitudinal width of, for example, 340 mm. The fixing belt 26 includes, for example, a sliding layer 26a made of a PFA layer or a PTFE layer having a thickness of 15 μm, an induction heating layer 26b made of electroformed nickel having a thickness of 30 to 50 μm, and 100 for example. An elastic layer 26c made of silicone rubber or the like having a thickness of ˜500 μm and a mold release made of, for example, a fluororesin or the like having a thickness of 30 to 50 μm to improve the releasability when melting and fixing an unfixed toner image at the fixing nip N The layer 26d is laminated. The induction heating layer 26a may be formed by mixing metal powder such as copper, silver, or aluminum into polyimide resin having a thickness of 50 to 100 μm, for example.

  The belt support unit 55 includes a belt holding portion 59 and a pad holding portion 56, and is made of a metal such as aluminum, a heat resistant resin, or the like. The belt holding unit 59 has a curved shape in a cross-sectional view (side view), and holds the fixing belt 26 with respect to the induction heating unit 30 at a predetermined interval. The pad holding unit 56 holds the pressing pad 60.

  The pressure pad 60 is disposed facing the inner peripheral surface of the fixing belt 26 with a heat resistant resin such as a liquid crystal polymer resin, and faces the pressure roller 19 via the fixing belt 26. The pressing pad 60 presses the fixing belt 26 toward the pressure roller 19 side.

  The pressure roller 19 includes a cylindrical cored bar 19a such as iron, a 5 mm thick silicone rubber elastic layer 19b formed on the cored bar 19a, and a thickness of, for example, 50 μm covering the surface of the elastic layer 19b. A release layer 19c made of a fluororesin or the like, and the outer diameter thereof is set to 30 mm, for example. The pressure roller 19 is rotated, for example, by a driving source such as a motor (not shown), and the fixing belt 26 is driven to rotate by the rotation of the pressure roller 19. A nip portion N is formed at a portion where the pressure roller 19 and the fixing belt 26 are in pressure contact, and in the nip portion N, an unfixed toner image on the sheet 9 to be conveyed is heated and pressed to form a toner image on the sheet 9. To fix.

  The induction heating unit 30 includes an exciting coil 37, a bobbin 38, and a magnetic core 39, and heats the fixing belt 26 by electromagnetic induction. The induction heating unit 30 extends in the width direction of the fixing belt 26 (the front and back direction in FIG. 7) and is disposed to face the fixing belt 26 so as to surround substantially half of the outer peripheral surface of the fixing belt 26. The exciting coil 37 is connected to a power source (not shown), and generates an alternating magnetic flux by a high frequency current supplied from the power source. The magnetic flux from the exciting coil 37 passes through the magnetic core 39, is guided in a direction parallel to the paper surface of FIG. 7, and passes along the induction heating layer 26 a of the fixing belt 26. An eddy current is generated in the induction heat generation layer 26a due to a change in the alternating strength of the magnetic flux passing through the induction heat generation layer 26a. When an eddy current flows through the induction heating layer 26a, Joule heat is generated by the electrical resistance of the induction heating layer 26a, and the fixing belt 26 generates heat.

  When the fixing belt 26 is heated by the induction heating unit 30 that is a heating unit and rises to a predetermined temperature, the paper 9 sandwiched by the nip portion N is heated and is pressed by the pressure roller 19. The powdery toner on the paper 9 is melted and fixed on the paper 9. As described above, the fixing belt 26 is made of a thin material having good thermal conductivity and has a small heat capacity. Therefore, the fixing device 5 is activated in a short time, and image formation is started quickly.

  A detailed configuration of the belt support unit 55 will be described with reference to FIG. The belt holding portion 59 of the belt support unit 55 includes a rotation holding portion 59a and a restriction flange portion 59b that is a meandering restriction portion. The rotation holding portion 59a holds the fixing belt 26 in an arc shape and suspends the fixing belt 26 together with the pressing pad 60 so as to be rotatable. The regulating flange portion 59b is provided to protrude from the outer peripheral surface of the rotation holding portion 59a at both ends in the longitudinal direction (A direction) of the rotation holding portion 59a, and the fixing belt 26 is brought into contact with the edge of the fixing belt 26 by abutting. To meander in the width direction (A direction). Depending on the shape, material, etc. of the belt holding portion 59, the belt holding portion 59 may be provided separately from the belt support unit 55, and the belt holding portion 59 may be integrally attached to the belt support unit 55. Good.

  One side surface portion 59c of the belt support unit 55 is provided with a support shaft 62 that is a support portion, and the other side surface portion 59d of the belt support unit 55 is provided with a screw shaft 64 that is a position adjustment portion.

  The support shaft 62 is fitted into a support hole 63 provided in the apparatus main body 5a. Since the support shaft 62 and the support hole 63 are fitted with a predetermined gap, the support shaft 62 can be tilted within the predetermined gap.

  The screw shaft 64 has a male screw formed on the outer peripheral surface thereof, and is screwed into the nut 66 through an adjustment hole 65 formed in the apparatus main body 5a. The adjustment hole 65 is formed in a circular hole larger than the outer diameter of the screw shaft 64. The belt support unit 55 has a support shaft 62 as a center, and a vertical direction (B direction, the pressure contact direction of the pressure roller 19 and the pressure pad 60) and a horizontal direction (in the figure) within a range in which the screw shaft 64 can move within the adjustment hole 65. 8 in the direction of the front and back surfaces of the paper surface, the pressure contact direction (B direction) of the pressure roller 19 and the pressure pad 60, and the axial direction (A direction) of the pressure roller 19). Can do. Further, the belt support unit 55 can be inclined in the direction between the vertical direction and the horizontal direction around the support shaft 62.

  A spring washer 67 is disposed between the nut 66 and the apparatus main body 5a. When the nut 66 is attached to the screw shaft 64, the nut 66 is inserted into the screw shaft 64 via the spring washer 67 even when the screw shaft 64 is inserted with a slight inclination with respect to the adjustment hole 65 by adjusting the position of the belt support unit 55. Therefore, the nut 66 is fixed to the apparatus main body 5a without loosening.

  Before fixing the belt support unit 55 to the apparatus main body 5a, the belt support unit 55 is inclined with respect to the axial direction (A direction) of the pressure roller 19 by adjusting the position of the screw shaft 64 in the adjustment hole 65. Adjusted. By performing this adjustment, the belt meandering between the pressure roller 19 and the pressing pad 60 is suppressed when the fixing belt 26 circulates by rotation of the pressure roller 19.

  Specifically, the support shaft 62 of the belt support unit 55 is fitted into the support hole 63 of the apparatus main body 5 a, and the screw shaft 64 is inserted into the adjustment hole 65, and then the spring washer 67 is fitted into the screw shaft 64. In this state, the belt support unit 55 is swung in the vertical direction, the horizontal direction, or the direction between the vertical direction and the horizontal direction so that the inclination of the pressing pad 60 with respect to the axial direction of the pressure roller 19 is minimized. The screw shaft 64 is held (adjusted) in the adjustment hole 65. After the position adjustment, the belt support unit 55 is fixed to the mounting body 5a by screwing the nut 66 into the screw shaft 64.

  In this manner, the belt support unit 55 is inclined in the vertical direction, the horizontal direction, or the direction between the vertical direction and the horizontal direction, and the pressure of the pressing pad 60 with respect to the axial direction of the pressure roller 19 is adjusted. The pressure roller 19 and the pressure pad 60 due to various factors such as the inclination of the mutual axis of the roller 19 and the pressure pad 60, the variation in accuracy of the cylindrical shape of the pressure roller 19, and the balance of the pressure force in the axial direction of the nip portion N. Meandering of the fixing belt 26 can be suppressed. As a result, damage such as cracks and breakage of the fixing belt 26 due to the belt meandering is reduced.

  In the second embodiment, the belt support unit 55 is inclined in the horizontal direction or the vertical direction. However, the present invention is not limited to this, and the belt meandering is performed by inclining the belt support unit 55 in the horizontal direction. In the same way as in the first embodiment, the arc hole 45g may be configured as a position adjustment unit and the support hole 45f may be configured as a support unit.

  On the other hand, in the first embodiment, the configuration in which the belt support unit 55 is inclined in the horizontal direction is shown. However, the present invention is not limited to this, and the belt support unit 55 needs to be inclined in the horizontal direction or the vertical direction. In the same manner as in the second embodiment, the screw shaft 64 that is movable in the adjustment hole 65 may be configured as a position adjustment unit, and the support shaft 62 may be configured as a support unit.

  In the first embodiment, the fixing belt 26 circulates by rotating the pressure roller 19. However, the present invention is not limited to this, and the fixing roller 23 or the suspension roller 27 is rotationally driven. Accordingly, the fixing belt 26 may be configured to circulate.

  In the first embodiment, the meandering restricting portion is provided on the suspension roller 27. Alternatively, the meandering restricting portion may be provided on the fixing roller 23, and both the suspension roller 27 and the fixing roller 23 are provided. May be provided. Moreover, in the said 1st and 2nd embodiment, although the meandering control part was comprised by the control flange parts 27b and 59b which protrude from the outer peripheral surface of a rotation holding part, this invention is not limited to this. The meandering restricting portion may be formed by an inclined surface whose diameter is smaller than that of the rotation holding portion, and the end portion of the fixing belt 26 may be in contact with the inclined surface to restrict the meandering of the belt.

  INDUSTRIAL APPLICABILITY The present invention can be used for a fixing device used in a copying machine, a printer, a facsimile, a composite machine thereof, and an image forming apparatus including the fixing device, and in particular, includes a fixing device that restricts meandering of a fixing belt and the fixing device. It can be used for an image forming apparatus.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 5 Fixing apparatus 5a Apparatus main body 18 Heating part 19 Pressure roller 23 Fixing roller (pressing member)
26 Fixing belt 27 Suspension roller (suspension member)
27a Rotation holding part 27b Restriction flange part (meandering restriction part)
30 Induction heating unit (heating means)
45 belt support unit 45a bearing 45b flat surface 45c bearing 45d first protrusion 45e second protrusion 45f support hole (support part)
45g Arc hole (position adjustment part)
45h Side wall 47 Support shaft 48 Screw 51, 52, 53 Rotating shaft 55 Belt support unit 56 Pad holding portion 59 Belt holding portion (suspension member)
59a Rotation holding part 59b Restriction flange part (meandering restriction part)
59c, 59d Side surface 60 Press pad (press member)
62 Support shaft (support part)
63 Support hole 64 Screw shaft (position adjustment part)
65 Adjustment hole 66 Nut 67 Spring washer N Nip part

Claims (8)

An endless fixing belt heated by a heating means;
A pressure roller disposed opposite to the outer peripheral surface of the fixing belt;
A pressing member that is disposed to face the inner peripheral surface of the fixing belt and presses against the pressure roller via the fixing belt;
A suspension member that is disposed to face the inner peripheral surface of the fixing belt and suspends the fixing belt in a circulating manner together with the pressing member;
A belt support unit that supports the pressing member and the suspension member;
In a fixing device that melts and fixes an unfixed toner image on a recording medium when the recording medium passes through a nip portion between the fixing belt and the pressure roller,
The belt support unit is provided at one end of the fixing belt in a direction orthogonal to the traveling direction of the fixing belt, and a support portion that rotatably supports the belt supporting unit with respect to the apparatus main body, and orthogonal to the traveling direction of the fixing belt. A position adjustment unit that is provided at the other end in the direction to be fixed and is fixed to the apparatus main body by adjusting the inclination of the belt support unit with respect to the axial direction of the pressure roller around the support unit. A fixing device.   The fixing device according to claim 1, wherein the fixing belt is circulated while being driven by the pressure roller.   The belt support unit is adjustable in inclination in a direction orthogonal to both the pressure contact direction of the pressure roller and the pressing member and the axial direction of the pressure roller. The fixing device according to claim 2. The support portion is a support hole that is rotatably fitted around a support shaft provided in the apparatus main body,
The position adjusting portion is an arc hole formed on a circumference around the support hole,
The belt support unit is fixed to the apparatus main body with a screw inserted through the arc hole after the inclination of the pressure roller with respect to the axial direction is adjusted along the arc hole with the support shaft as a center. The fixing device according to claim 3.   5. The meandering restricting portion for restricting meandering in the width direction of the fixing belt is provided on at least one of the pressing member and the suspension member. 6. Fixing device. The pressing member comprises a fixing roller that is rotatably supported by the belt support unit,
The fixing device according to claim 1, wherein the suspension member includes a suspension roller that is rotatably supported by the belt support unit. The pressing member comprises a pressing pad fixedly supported by the belt support unit,
The fixing device according to claim 1, wherein the suspension member includes a belt holding portion having a curved shape in a side view fixedly supported by the belt support unit.   An image forming apparatus comprising the fixing device according to claim 1.

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