Fixing device and image forming apparatus including the same

Abstract

To provide a fixing device that can improve, with a simple configuration, accuracy of positioning a driving member to prevent occurrence of faulty connection and unusual sound, and an image forming apparatus including the same.SOLUTION: A fixing device comprises a fixing member, a housing that accommodates the fixing member, a side face cover, a pressure mechanism, and a unit side gear, and fuses and fixes an unfixed toner image on a sheet that passes through a fixing nip part. The fixing member comprises a rotating body to be heated, and a pressure rotating body that is brought into pressure contact with the rotating body to be heated to form a fixing nip part. The side face cover is mounted on at least one end side in the longitudinal direction of the housing. The pressure mechanism adjusts the contact pressure force between the rotating body to be heated and the pressure rotating body. The unit side gear is connected to a body side gear provided on a side of an image forming apparatus body, and transmits driving force to the fixing member or the pressure mechanism. The side face cover has a first positioning part for performing positioning of the unit side gear, and a second positioning part for performing positioning of the body side gear.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present invention relates to a fixing device used in an image forming apparatus such as a copying machine, a printer, a facsimile machine, and a multifunction machine thereof, and an image forming apparatus including the same.

Background Art

[0002] In an image forming apparatus using an electrophotographic method, in order to fix a toner image on a sheet, a fixing device including a fixing member formed by pressing a fixing roller or a fixing belt (a rotating member to be heated) and a pressure roller (a rotating member to apply pressure) is widely used. In this fixing device, heat and pressure are applied to the toner image through a sheet in a fixing nip portion formed by the fixing roller or the fixing belt and the pressure roller, and the toner image is melted and fixed on the sheet.

[0003] In the fixing device as described above, since the rotating member to be heated and the rotating member to apply pressure are in pressure contact, when a jam occurs, it is necessary to release the pressure contact to remove the sheet. For example, Patent Document 1 discloses a fixing device capable of releasing the pressure contact force between a fixing roller (fixing member) and a pressure roller (pressure applying member), and the pressure contact force between the pressure roller (pressure applying member) and a cleaning roller (cleaning member) when the main body cover is opened.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the conventional configuration, the pressure-release input gear on the main body side and the gear that joints with the fixing unit side were held as separate parts. However, when the gear on the main body side and the gear on the fixing unit side are held as separate parts, the arrangement of the gears can deviate by up to the component tolerance at most. As a result, it causes problems such as poor gear meshing and abnormal noise. Also, since the number of components increases, it hinders the miniaturization and weight reduction of the fixing device and the main body of the image forming apparatus. It should be noted that the above problems are not limited to the pressure-release drive train that performs pressure release between the heated rotating body and the pressurized rotating body, but the same can be said for the drive train that inputs driving force to the heated rotating body.

[0006] In view of the above problems, an object of the present invention is to provide a fixing device capable of improving the positioning accuracy of a drive member with a simple configuration and suppressing problems such as connection failure and abnormal noise generation due to displacement of a connection part, and an image forming apparatus including the same.

Means for Solving the Problems

[0007] To achieve the above object, a first configuration of the present invention includes a fixing member, a housing, a side cover, a pressurizing mechanism, and a unit-side gear, and is a fixing device that heats and pressurizes a sheet passing through a fixing nip portion to melt and fix an unfixed toner image on the sheet. The fixing member is composed of a heated rotating body and a pressurized rotating body that is pressed against the heated rotating body to form a fixing nip portion. The housing houses the fixing member. The side cover is attached to at least one end side in the longitudinal direction of the housing. The pressurizing mechanism adjusts the pressure contact force between the heated rotating body and the pressurized rotating body. The unit-side gear is connected to a main body-side gear provided on the main body side of the image forming apparatus and transmits a driving force to the fixing member or the pressurizing mechanism. The side cover has a first positioning portion for positioning the unit-side gear and a second positioning portion for positioning the main body-side gear.

Effects of the Invention

[0008] According to the first configuration of the present invention, the positioning accuracy between the unit-side gear and the main body-side gear on the image forming apparatus main body side is improved, and the axial distance (gear pitch) is maintained constant. Therefore, it is possible to suppress poor meshing (tooth skipping) between the unit-side gear and the main body-side gear and the generation of abnormal noise. In addition, since the positioning between the unit-side gear and the main body-side gear can be achieved only by the side cover, the number of parts can be reduced, and the fixing device can be made smaller and lighter.

Brief Description of the Drawings

[0009]

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Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing the internal structure of an image forming apparatus 100 according to an embodiment of the present invention. Inside the image forming apparatus 100 (here, a color printer), four image forming units Pa, Pb, Pc, and Pd are arranged in order from the upstream side in the conveyance direction (left side in FIG. 1). These image forming units Pa to Pd are provided corresponding to images of four different colors (yellow, cyan, magenta, and black), and yellow, cyan, magenta, and black images are sequentially formed by the respective steps of charging, exposure, development, and transfer.

[0011] Photoconductor drums (image carriers) 1a, 1b, 1c, and 1d that carry visible images (toner images) of each color are arranged in these image forming units Pa to Pd. Further, an intermediate transfer belt (intermediate transfer member) 8 that rotates counterclockwise in FIG. 1 by a belt drive motor (not shown) is provided adjacent to each of the image forming units Pa to Pd. The toner images formed on these photoconductor drums 1a to 1d are sequentially primary transferred and superimposed onto the intermediate transfer belt 8 that moves while contacting each of the photoconductor drums 1a to 1d. Thereafter, the toner image primary transferred onto the intermediate transfer belt 8 is secondary transferred onto transfer paper P as an example of a recording medium by a secondary transfer roller 9. Further, the transfer paper P onto which the toner image has been secondary transferred is discharged from the main body of the image forming apparatus 100 after the toner image is fixed by a fixing device 14. While rotating the photoconductor drums 1a to 1d clockwise in FIG. 1, an image forming process for each of the photoconductor drums 1a to 1d is executed.

[0012] The transfer paper P onto which the toner image is secondarily transferred is housed in a paper cassette 16 disposed at the lower part of the main body of the image forming apparatus 100, and is conveyed along a paper conveyance path 19 to the nip portion between the secondary transfer roller 9 and the driving roller 11 of the intermediate transfer belt 8 via a paper feed roller 12 and a resist roller pair 13. A sheet made of a dielectric resin is used for the intermediate transfer belt 8, and a seamless belt having no seam is mainly used. Further, a blade-shaped belt cleaner 25 for removing toner and the like remaining on the surface of the intermediate transfer belt 8 is disposed on the downstream side of the secondary transfer roller 9.

[0013] Next, the image forming units Pa to Pd will be described. Around and below the rotatably arranged photosensitive drums 1a to 1d, charging devices 2a, 2b, 2c, and 2d for charging the photosensitive drums 1a to 1d, an exposure device 5 for exposing the photosensitive drums 1a to 1d with image information, developing devices 3a, 3b, 3c, and 3d for forming a toner image on the photosensitive drums 1a to 1d, and cleaning devices 7a, 7b, 7c, and 7d for removing the developer (toner) and the like remaining on the photosensitive drums 1a to 1d are provided.

[0014] When image data is input from a host device such as a personal computer, first, the charging devices 2a to 2d uniformly charge the surfaces of the photosensitive drums 1a to 1d. Next, light irradiation is performed according to the image data by the exposure device 5 to form an electrostatic latent image corresponding to the image data on each of the photosensitive drums 1a to 1d. The developing devices 3a to 3d are each filled with a predetermined amount of a two-component developer containing yellow, cyan, magenta, and black toner. When the ratio of the toner in the two-component developer filled in each of the developing devices 3a to 3d falls below a specified value due to the formation of the toner image described later, toner is replenished from toner containers 4a to 4d to each of the developing devices 3a to 3d. The toner in this developer is supplied onto the photosensitive drums 1a to 1d by the developing devices 3a to 3d and adheres electrostatically. Thereby, a toner image corresponding to the electrostatic latent image formed by the exposure from the exposure device 5 is formed.

[0015] Then, a transfer electric field is applied at a predetermined transfer voltage between the primary transfer rollers 6a to 6d and the photosensitive drums 1a to 1d by the primary transfer rollers 6a to 6d, and the yellow, cyan, magenta, and black toner images on the photosensitive drums 1a to 1d are primarily transferred onto the intermediate transfer belt 8. These images are formed with a predetermined positional relationship that has been determined in advance. Then, in preparation for the subsequent formation of a new electrostatic latent image, toner and the like remaining on the surfaces of the photosensitive drums 1a to 1d after primary transfer are removed by the cleaning devices 7a to 7d.

[0016] The intermediate transfer belt 8 is stretched between the upstream driven roller 10 and the downstream drive roller 11. When the intermediate transfer belt 8 starts to rotate counterclockwise with the rotation of the drive roller 11 by a belt drive motor (not shown), the transfer paper P is conveyed from the registration roller pair 13 to the secondary transfer nip portion N1 (see FIG. 2) between the drive roller 11 and the secondary transfer roller 9 provided adjacent thereto at a predetermined timing. Then, the toner image on the intermediate transfer belt 8 is secondarily transferred onto the transfer paper P passing through the secondary transfer nip portion N1.

[0017] The transfer paper P onto which the toner image has been secondarily transferred is conveyed to the fixing device 14. The fixing device 14 has a fixing belt 14a and a pressure roller 14b (both see FIG. 2). The fixing belt 14a is heated by a heater (not shown). The pressure roller 14b is pressed against the fixing belt 14a to form a fixing nip portion N2 (see FIG. 5) and applies a rotational driving force to the fixing belt 14a. Note that an induction heating portion may be provided outside the fixing belt 14a instead of the heater.

[0018] The transfer paper P conveyed to the fixing device 14 is heated and pressed by the fixing belt 14a and the pressure roller 14b, so that the toner image is fixed on the surface of the transfer paper P, and a predetermined full-color image is formed. After the transfer paper P on which the full-color image is formed passes through the fixing discharge roller pair 24 (see FIG. 2), the conveyance direction is distributed by the branch portion 15 branched in a plurality of directions, and then (or after being sent to the duplex conveyance path 20 and images are formed on both sides), it is discharged to the discharge tray 18 by the discharge roller pair 17.

[0019] FIG. 2 is a partial cross-sectional view around the paper conveyance path 19 and the duplex conveyance path 20 in the image forming apparatus 100 of the present embodiment. The opening / closing cover 21 constitutes the side surface 102 of the image forming apparatus 100 and is rotatably supported by a cover support shaft 21a provided below the main body of the image forming apparatus 100. The inner surface of the opening / closing cover 21 constitutes one (outer) conveyance surface of the duplex conveyance path 20.

[0020] A handle portion 22 is provided on the side surface of the opening / closing cover 21. One end of the handle portion 22 engages with an engagement pin (not shown) provided on the front frame and the rear frame of the main body of the image forming apparatus 100 to hold the opening / closing cover 21 in a closed state. When opening the opening / closing cover 21, the handle portion 22 is rotated to release the engagement with the engagement pin.

[0021] A conveyance unit 23 is arranged inside the opening / closing cover 21. The conveyance unit 23 is rotatably supported by the main body of the image forming apparatus 100 around a unit support shaft 23a, and constitutes a part of the conveyance surfaces of the duplex conveyance path 20 and the paper conveyance path 19. The duplex conveyance path 20 extends in the vertical direction along the side surface 102 of the image forming apparatus 100 between the inner surface of the opening / closing cover 21 and the outer surface of the conveyance unit 23, and is curved in a substantially C shape to merge with the paper conveyance path 19. On the inner surface of the conveyance unit 23, in order from the upstream side (lower side in FIG. 2) in the conveyance direction of the transfer paper P, a roller 13b on one side that constitutes the registration roller pair 13 together with the main body side roller 13a and the secondary transfer roller 9 are attached.

[0022] By rotating only the opening / closing cover 21 in the opening direction with respect to the image forming apparatus 100 to an open state, the duplex conveyance path 20 is widely exposed. Further, by rotating the opening / closing cover 21 together with the conveyance unit 23 in the opening direction, the conveyance unit 23 is separated from the main body side of the image forming apparatus 100 and the paper conveyance path 19 is widely exposed. On the other hand, by rotating the opening / closing cover 21 together with the conveyance unit 23 in the closing direction to a closed state, the conveyance unit 23 abuts against the main body side of the image forming apparatus 100, the secondary transfer roller 9 is pressed against the driving roller 11 via the intermediate transfer belt 8, and the secondary transfer nip portion N1 is formed.

[0023] Next, the configuration of the fixing device 14 will be described. FIG. 3 is a perspective view of the fixing device 14 as viewed from the downstream side (the left side in FIG. 2) in the discharge direction of the transfer paper P from the image forming apparatus 100. FIG. 4 is a side cross-sectional view of the fixing device 14 cut at the central portion in the longitudinal direction.

[0024] The fixing device 14 includes a housing 30, side covers 31a and 31b, and a stay 31c. A fixing belt 14a and a pressure roller 14b are housed in the housing 30. Above the housing 30, a roller 24a on one side (the left side in FIG. 2) constituting the fixing discharge roller pair 24 is supported.

[0025] The side covers 31a and 31b are respectively fixed to side plates 30a and 30b arranged at both ends in the longitudinal direction of the housing 30. The stay 31c is made of metal and is a plate-like member fixed along the longitudinal direction of the housing 30. At both ends in the longitudinal direction of the stay 31c, a pair of spring receiving portions 40 for supporting one end side (lower end portion) of a pressure spring 35 (see FIG. 5) of the pressure mechanism 32 are formed.

[0026] On the side of the side cover 31a, a drive input gear 60 and a pressure release gear 61 are arranged. The drive input gear 60 meshes with a roller drive gear 142 (see FIG. 5) fixed to the rotating shaft 141 of the pressure roller 14b. When a rotational driving force is transmitted from a fixing drive motor (not shown) to the drive input gear 60 via a drive output gear 80 (see FIG. 13) on the main body side of the image forming apparatus 100, the pressure roller 14b rotates at a predetermined speed. As a result, the fixing belt 14a pressed against the pressure roller 14b also rotates following the pressure roller 14b.

[0027] FIG. 5 is a side view showing the configuration around the pressure mechanism 32 of the fixing device 14. A roller drive gear 142 is fixed to the shaft 141 of the pressure roller 14b. A drive input gear 60 is connected to the roller drive gear 142.

[0028] Inside the fixing belt 14a, a nip forming member 41 and a belt guide 42 are arranged. The nip forming member 41 forms a fixing nip portion N2 through which the transfer paper P is inserted by contacting the pressure roller 14b via the fixing belt 14a. The nip forming member 41 is made of a heat-resistant resin such as a liquid crystal polymer or an elastic material such as silicone rubber, and an elastomer may be arranged on the opposing surface to the fixing belt 14a to enhance slidability.

[0029] The belt guide 42 has an arcuate shape in cross-section and contacts the inner peripheral surface of the fixing belt 14a except for the opposing surface to the nip forming member 41. The belt guide 42 applies a predetermined tension to the fixing belt 14a and holds the fixing belt 14a in an arcuate shape from the inside. The belt guide 42 is composed of a metal plate extending along the axial direction of the fixing belt 14a and having substantially the same length as the fixing belt 14a.

[0030] A pair of pressure mechanisms 32 are provided at both axial ends of the fixing belt 14a and the pressure roller 14b. The pressure mechanism 32 includes a pressure plate 33, a pressure spring 35, and an eccentric cam 37.

[0031] The pressure plate 33 is disposed opposite to a belt holder 143 that supports both longitudinal ends of the fixing belt 14a, the nip forming member 41, and the belt guide 42. The pressure plate 33 has a fulcrum portion 33a supported by the housing 30 (see FIG. 3) of the fixing device 13 and is swingable in a direction approaching or separating from the belt holder 143.

[0032] The compression spring 35 biases the belt holder 143 in a direction approaching the pressure roller 14b. More specifically, one end of the compression spring 35 is supported by a spring receiving portion 40 (see FIG. 3) formed on the stay 31c. The other end of the compression spring 35 is externally inserted into a boss (not shown) of the belt holder 143 that protrudes through a through hole 33b formed in the pressure plate 33 and contacts the pressure plate 33. The inner diameter of the through hole 33b is smaller than the outer diameter of the compression spring 35, and the compression spring 35 contracts between the pressure plate 33 and the spring receiving portion 40 due to the swing of the pressure plate 33.

[0033] The eccentric cam 37 is disposed on the same side as the belt holder 143 with respect to the pressure plate 33 (the right side in FIG. 5). The eccentric cam 37 is integrally formed with a pressure release gear 61 that inputs a driving force to the pressurizing mechanism 32. When the eccentric cam 37 rotates together with the pressure release gear 61, the outer diameter of the eccentric cam 37 that contacts the pressure plate 33 changes.

[0034] FIGS. 6 and 7 are side views showing the pressurized state and the pressure release state by the pressurizing mechanism 32, respectively. As shown in FIG. 6, when the small diameter portion of the eccentric cam 37 faces the pressure plate 33, a certain pressing force acts on the belt holder 143 by the biasing force of the compression spring 35. Thereby, the pressure roller 14b is pressed against the nip forming member 41 to form a fixing nip portion N2 (see FIG. 5) between the fixing belt 14a. In the state of FIG. 6, the light shielding portion 33c formed at the swing end of the pressure plate 33 has retreated from the detection portion of the PI sensor 70, and the PI sensor 70 detects that it is in the pressurized state.

[0035] When the eccentric cam 37 rotates by a predetermined amount from the state shown in FIG. 6 and the large-diameter portion of the eccentric cam 37 contacts the pressure plate 33 as shown in FIG. 7, the pressure plate 33 is pressed in a direction away from the belt holder 143 against the biasing force of the pressure spring 35. As a result, the pressure spring 35 is compressed between the pressure plate 33 and the spring receiving portion 40, and the pressure acting from the pressure plate 33 to the belt holder 143 is weakened. In the state of FIG. 7, the light-shielding portion 33c shields the detection portion of the PI sensor 70, and the PI sensor 70 detects that the pressure release state is present.

[0036] FIGS. 8 and 9 are perspective views of the side cover 31a of the fixing device 14 as viewed from the inside and the outside, respectively. The side cover 31a is attached to one end side (the left side in FIG. 3) of the housing 30 and constitutes a part of the exterior surface of the fixing device 14. The side cover 31a is formed with a first bearing portion 311, a second bearing portion 312, a third bearing portion 313, a gear cover portion 314, and a positioning pin 315.

[0037] The first bearing portion 311 is a circular through-hole into which the drive transmission shaft 61a (see FIG. 10) of the pressure release gear 61 of the pressure mechanism 32 is inserted. The inner diameter of the first bearing portion 311 is slightly larger than the diameter of the drive transmission shaft 61a. The first bearing portion 311 rotatably supports the drive transmission shaft 61a and positions the drive transmission shaft 61a.

[0038] The second bearing portion 312 is a U-shaped groove in which a notch portion 312a is formed in a part of the circumferential direction of a cylindrical through-hole. The rotation shaft 81a (see FIG. 12) of the pressure release input gear 81 on the main body side of the image forming apparatus 100 is inserted into the second bearing portion 312. The second bearing portion 312 rotatably supports the rotation shaft 81a and positions the rotation shaft 81a.

[0039] The third bearing portion 313 is a circular through-hole into which a coupling (not shown) for driving the roller 24a (see FIG. 3) constituting the fixing discharge roller pair 24 is inserted. The third bearing portion 313 rotatably supports the coupling for driving the roller 24a and positions the coupling.

[0040] The gear cover portion 314 is cylindrical and covers the drive input gear 60 (see FIG. 5) from the outside. The inner diameter of the gear cover portion 314 is slightly larger than the diameter of the drive input gear 60. A circular opening 314a is formed in the gear cover portion 314. By exposing the side surface (coupling surface) of the drive input gear 60 from the opening 314a, the drive input gear 60 can be connected to the drive output gear 80 (see FIG. 13) on the main body side of the image forming apparatus 100.

[0041] The positioning pin 315 is inserted into a positioning hole (not shown) in the side plate 30a (see FIG. 3) of the housing 30 when the side cover 31a is attached to the housing 30. Thereby, the side cover 31a is positioned with respect to the side plate 30a.

[0042] FIG. 10 is a perspective view showing a state in which the side cover 31a is attached to the housing 30 of the fixing device 14. FIG. 11 is a view showing a state in which the pressure release gear 61 is attached to the drive transmission shaft 61a from the state of FIG. 10. When attaching the side cover 31a to the housing 30, the drive transmission shaft 61a is inserted into the first bearing portion 311, the drive input gear 60 is inserted into the gear cover portion 314, and the positioning pin 315 (see FIG. 8) formed on the inner surface of the side cover 31a is inserted into a positioning hole (not shown) formed in the side plate 30a of the housing 30.

[0043] Thereby, the first bearing portion 311 of the side cover 31a and the drive transmission shaft 61a on the housing 30 side are aligned. The drive transmission shaft 61a has a cross-sectional D-cut shape and supports the pressure release gear 61 so as to be movable in the thrust direction and non-rotatable in the circumferential direction.

[0044] The pressure release gear 61 is connected to the pressure release gear 61 on the other side (side cover 31b side) by the drive transmission shaft 61a. The rotational driving force input from the pressure release input gear 81 to the pressure release gear 61 is transmitted to the pressure release gear 61 on the other side and the eccentric cam 37 via the drive transmission shaft 61a.

[0045] Further, the gear cover portion 314 of the side cover 31a is aligned with the drive input gear 60 on the housing 30 side, and the drive input gear 60 is housed in the gear cover portion 314. Input-side coupling teeth 60a are formed on the side surface (the surface facing the drive output gear 80) of the drive input gear 60. The input-side coupling teeth 60a are exposed from the opening 314a of the gear cover portion 314.

[0046] FIG. 12 is a perspective view showing a state where the pressure release gear 61 and the pressure release input gear 81 are connected. On the side frame 100a of the image forming apparatus 100 facing the side cover 31a, a drive output gear 80 (see FIG. 13) and a pressure release input gear 81 are arranged.

[0047] When the fixing device 14 is mounted on the main body of the image forming apparatus 100, the opening / closing cover 21 (see FIG. 2) of the image forming apparatus 100 is opened, and the fixing device 14 is inserted in the horizontal direction (from right to left in FIG. 2).

[0048] As the fixing device 14 is inserted, as shown in FIG. 12, the rotation shaft 81a of the pressure release input gear 81 is inserted into the second bearing portion 312 of the side cover 31a. More specifically, the rotation shaft 81a is inserted radially from the notch portion 312a of the second bearing portion 312 having a U-shaped groove. Thereby, the pressure release input gear 81 is positioned with respect to the side cover 31a. Further, since the drive transmission shaft 61a (see FIG. 10) of the pressure release gear 61 is inserted into the first bearing portion 311, the pressure release gear 61 is also positioned with respect to the side cover 31a. That is, both the pressure release gear 61 and the pressure release input gear 81 are positioned with respect to the side cover 31a.

[0049] FIG. 13 is a perspective view showing a state in which the drive input gear 60 and the drive output gear 80 are connected. As shown in FIG. 13, the drive output gear 80 is disposed on the side of the side frame 100a (see FIG. 12). Output-side coupling teeth 80a are formed on the side surface of the drive output gear 80 (the surface facing the drive input gear 60). The drive output gear 80 is movable in the thrust direction with respect to the side frame 100a and is biased inward of the side frame 100a by a spring (not shown).

[0050] As shown in FIG. 12, when the pressure release gear 61 and the pressure release input gear 81 are connected with the side cover 31a facing the side frame 100a, the drive output gear 80 also faces the drive input gear 60 on the fixing device 14 side. Then, as shown in FIG. 13, the output-side coupling teeth 80a of the drive output gear 80 and the input-side coupling teeth 60a of the drive input gear 60 mesh with each other in the thrust direction, enabling transmission of the rotational driving force from the drive output gear 80 to the drive input gear 60.

[0051] According to the above configuration, the positioning accuracy between the pressure release gear 61 on the fixing device 14 side and the pressure release input gear 81 on the main body side of the image forming apparatus 100 is improved, and the axial distance (gear pitch) is maintained constant. Therefore, it is possible to suppress defective meshing (tooth skipping) between the pressure release gear 61 and the pressure release input gear 81 and the generation of abnormal noise.

[0052] In addition, since the positioning of the pressure release gear 61 and the pressure release input gear 81 can be achieved only by the side cover 31a, the number of parts of the fixing device 14 can be reduced. Therefore, the fixing device 14 can be made smaller and lighter.

[0053] FIG. 14 is a side cross-sectional view showing a state in which the drive input gear 60 and the roller drive gear 142 are connected. Gear teeth 60b that mesh with the roller drive gear 142 are formed on the outer peripheral surface of the drive input gear 60. An annular flange portion 60c is formed between the input-side coupling teeth 60a and the gear teeth 60b. The gear cover portion 314 holds the drive input gear 60 by engaging the peripheral edge of the opening 314a with the flange portion 60c.

[0054] As shown in FIG. 14, since the drive input gear 60 is positioned by the gear cover portion 314 of the side cover 31a, the drive input gear 60 on the fixing device 14 side and the drive output gear 80 on the main body side of the image forming apparatus 100 are also indirectly positioned by the side cover 31a due to the engagement between the second bearing portion 312 and the rotation shaft 81a of the pressure release input gear 81. As a result, the positioning accuracy between the drive input gear 60 and the drive output gear 80 is also improved.

[0055] Furthermore, since the shaft 60d of the drive input gear 60 has a long protruding length from the housing 30, shaft deflection is likely to occur. Therefore, by holding the drive input gear 60 with the gear cover portion 314, shaft deflection of the shaft 60d can also be suppressed.

[0056] In addition, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, the belt heating type fixing device 14 including the endless fixing belt 14a as the heated rotating body is exemplified, but the present invention is similarly applicable to a fixing device including a heated rotating body other than the fixing belt 14a, such as a fixing roller.

[0057] Also, in the above-described embodiment, the color printer as shown in FIG. 1 is exemplified as the image forming apparatus 100, but the present invention is not limited to a color printer, and is applicable to an image forming apparatus including a fixing device, such as a color copying machine, a color multifunction machine, a monochrome printer, a monochrome copying machine, etc.

Industrial Applicability

[0058] The present invention can be used for a fixing device used in an image forming apparatus such as a copying machine, a printer, a facsimile machine, and a composite machine thereof. By using the present invention, it is possible to provide a fixing device capable of improving the positioning accuracy of a drive member with a simple configuration and suppressing problems such as connection failure and abnormal noise due to displacement of a connecting portion, and an image forming apparatus including the same.

Explanation of Reference Numerals

[0059] Pa - Pd Image Forming Unit 14 Fixing Device 14a Fixing Belt (Heated Rotating Body) 14b Pressing Roller (Pressing Rotating Body) 143 Belt Holder 30 Housing 30a, 30b Side Plates 30c Stay 31a, 31b Side Covers 311 First Bearing Part (First Positioning Part) 312 Second Bearing Part (Second Positioning Part) 312a Notch Part 313 Second Bearing Part 314 Gear Cover Part 32 Pressing Mechanism 33 Pressing Plate 35 Pressing Spring (Biasing Member) 37 Eccentric Cam 40 Spring Receiver Part 41 NiP Forming Member 42 Belt Guide 60 Driving Input Gear (Unit - Side Gear) 61 Pressure Release Gear (Unit - Side Gear) 80 Driving Output Gear (Main Body - Side Gear) 81 Pressure Release Input Gear (Main Body - Side Gear) 100 Image Forming Apparatus P Transfer Paper (Recording Medium) N2 Fixing NiP Part

Claims

1. A fixing member including a rotatable member to be heated and a pressure-applying rotatable member that is pressed against the rotatable member to be heated to form a fixing nip portion; A housing that houses the fixing member; A side cover attached to at least one end side in the longitudinal direction of the housing; A pressure-applying mechanism that adjusts the pressure contact force between the rotatable member to be heated and the pressure-applying rotatable member; A unit-side gear that is connected to a main body-side gear provided on the image forming apparatus main body side and transmits a driving force to the fixing member or the pressure-applying mechanism; In a fixing device that heats and presses a sheet passing through the fixing nip portion to melt and fix an unfixed toner image on the sheet, The side cover has a first positioning portion that positions the unit-side gear and a second positioning portion that positions the main body-side gear. A fixing device characterized by this.

2. The fixing device according to claim 1, wherein the second positioning portion positions the main body-side gear connected to the unit-side gear positioned by the first positioning portion.

3. The unit-side gear is a pressure release gear that transmits a driving force to the pressure-applying mechanism to release the pressure contact force, The main body-side gear is a pressure release input gear connected to the pressure release gear, The fixing device according to claim 2, wherein the first positioning portion is a first bearing portion that rotatably supports a drive transmission shaft on which the pressure release gear is mounted.

4. The fixing device according to claim 3, wherein the second positioning portion is a second bearing portion that rotatably supports the rotation shaft of the pressure release input gear.

5. The fixing device is inserted into the image forming apparatus main body in a direction orthogonal to the rotation shaft of the pressure release input gear, The fixing device according to claim 4, wherein the second positioning portion is a groove having a notch portion on the downstream side in the insertion direction of the fixing device and having a U-shape in side view.

6. The unit-side gear is a drive input gear that transmits a rotational driving force to the fixing member, The fixing device according to claim 1, wherein the first positioning portion is a gear cover portion that covers the outer peripheral surface of the drive input gear.

7. An image forming unit that forms a toner image on a recording medium; The fixing device according to any one of claims 1 to 6, which heats and presses the recording medium on which the toner image is formed by the image forming unit to fix the toner image on the recording medium; An image forming apparatus including the above.

Images