Belt unit, transfer device, and image forming apparatus

Abstract

To provide a belt unit with which, even when an axial external force acts upon a belt skew controlled roller, it is possible to suitably exercise belt skew control over a long period.SOLUTION: Provided is a belt unit 10 comprising: a belt member 9 which is stretched over a support rotor and driven to travel; a belt abutment member 24 which is disposed to a revolving shaft 21a of a first support rotor 21 and which, when an end of the belt member moves in the axial direction of the revolving shaft, contacts the end and is movable in the axial direction together with the belt member; a support rotor displacement member 25 which is movable in the axial direction following the movement of said member, causing the first support rotor to be displaced; a guide member 26c for regulating the movement direction of the support rotor displacement member; a support member 30 for rotatably supporting the first support rotor and the revolving shaft; a regulation member 34 for regulating the movement of the first support rotor and the revolving shaft in the axial direction; and an elastically deformable intermediate member 39 which is disposed between the support member and the regulation member in the axial direction and prevents the support member and the regulation member from contacting each other.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a belt unit, a transfer device, and an image forming apparatus. [Background technology]

[0002] Conventionally, there is known a belt unit having a belt that is stretched over a plurality of rollers and driven to run. In this belt unit, belt deviation, in which the belt moves axially during running, can occur due to the parallelism of the plurality of rollers around which the belt is stretched, deviation in outer diameter, deviation in circumferential length of the belt, and the like. When such belt deviation occurs, there is known a technique for inclining one of the plurality of rollers around which the belt is stretched axially relative to the other rollers, thereby applying a moving force to the belt in the direction opposite to the belt movement direction in the belt deviation state (see, for example, Patent Documents 1, 2, and 3). Summary of the Invention [Problem to be solved by the invention]

[0003] In the technologies described in Patent Documents 1, 2, and 3, one roller is tilted to control belt misalignment, but this tilted roller itself is also subjected to an external force that moves it in the axial direction. As a result, the restricting member that restricts the axial movement of the roller and the support member that rotatably supports the roller come into contact and slide against each other, which can cause unexpected friction and wear between the two and reduce the accuracy of the roller's axial positioning. If the positioning accuracy decreases, the accuracy of roller misalignment control decreases, which causes the problem of the belt misalignment control not functioning properly. The present invention aims to solve the above-mentioned problems and provide a belt unit, transfer device, and image forming apparatus that can effectively control belt misalignment for a long period of time even when an external force in the axial direction acts on the roller that controls the belt misalignment. [Means for solving the problem]

[0004] The invention of claim 1 includes a belt member that is stretched over a plurality of support rotors and is driven to run by the rotation of the plurality of support rotors; a belt abutment member that is provided on a rotation shaft of a first support rotor that is one of the plurality of support rotors and that comes into contact with an end of the belt member when the end moves in the axial direction of the rotation shaft and is movable in the axial direction together with the belt member; a support rotor displacement member that is provided on the rotation shaft and is movable in the axial direction as the belt abutment member moves and has an inclined surface that displaces the first support rotor; a guide member that comes into contact with the inclined surface and regulates the moving direction of the support rotor displacement member; a support member that rotatably supports the first support rotor and the rotation shaft; a regulation member that regulates movement of the first support rotor and the rotation shaft in the axial direction; and a support member that is provided between the support member and the regulation member in the axial direction and regulates the support member. The face and the regulating member The contact surface is formed on both the Elastic deformation This prevents friction between the support member and the regulating member. Intermediate parts and 、 The present invention is characterized by having the following. [Effects of the Invention]

[0005] According to the present invention, by providing an elastically deformable intermediate member between the support member and the regulating member, the difference in the amount of movement between the support member and the regulating member is absorbed by the elastic deformation of the intermediate member. This prevents unexpected friction and wear between the support member and the regulating member due to direct sliding between the support member and the regulating member, and prevents a decrease in the axial positioning accuracy of the first support rotor and the rotation shaft. As a result, it is possible to provide a belt unit that can perform good belt misalignment control over a long period of time, even if an external force acts in the axial direction on the first support rotor that controls the belt misalignment, and a transfer device and an image forming apparatus using the same. [Brief explanation of the drawings]

[0006] [Figure 1] 1 is a schematic front view of an image forming apparatus to which an embodiment of the present invention can be applied; [Figure 2] FIG. 10 is a schematic diagram illustrating a conventional belt deviation regulation means. [Figure 3] FIG. 3 is a schematic cross-sectional view of FIG. 2 taken along the cross-sectional line AA. [Figure 4] 5A and 5B are schematic diagrams illustrating a belt deviation regulating unit according to an embodiment of the present invention. [Figure 5] FIG. 5 is a schematic cross-sectional view of FIG. 4 taken along the cross-sectional line DD. DETAILED DESCRIPTION OF THE INVENTION

[0007] 1 shows a color copier as an image forming apparatus according to one embodiment of the present invention. Process cartridges 3Y, 3C, 3M, and 3K for forming toner images of yellow (Y), cyan (C), magenta (M), and black (K) are arranged in the center of a main body 2 of the color copier 1. Each process cartridge 3 is provided with a corresponding photosensitive drum 4Y, 4C, 4M, or 4K. 1, charging devices 5Y, 5C, 5M, and 5K, developing devices 6Y, 6C, 6M, and 6K, and photosensitive drum cleaning devices 7Y, 7C, 7M, and 7K are arranged around each photosensitive drum 4 that rotates clockwise. An optical unit 8 that irradiates each photosensitive drum 4 with laser light is arranged below each process cartridge 3.

[0008] Above each process cartridge 3, there is provided an intermediate transfer unit 10 as a belt unit having an intermediate transfer belt 9, which is a belt member, onto which a toner image formed by each process cartridge 3 is transferred. The intermediate transfer unit 10 has a plurality of rollers, which are a plurality of supporting rotary bodies, that support the intermediate transfer belt 9, and the intermediate transfer belt 9 is stretched over a secondary transfer opposing roller 20, a tension roller 21, and an inlet roller 22. Of the rollers 20, 21, and 22, the secondary transfer opposing roller 20 is rotationally driven by a drive motor (not shown), thereby driving the intermediate transfer belt 9 to run in the counterclockwise direction in FIG. The intermediate transfer belt 9 may have a single-layer structure or a multi-layer structure, and in the case of a single-layer structure, it is preferably formed from polyvinylidene fluoride, polycarbonate, polyimide, etc. In the case of a multi-layer structure, it is preferable that the base layer is formed from a fluororesin, polyvinylidene fluoride sheet, or polyimide resin with low elongation, and the surface is covered with a coating layer with good smoothness, such as a fluororesin.

[0009] Primary transfer rollers 11Y, 11C, 11M, and 11K are provided on the inner circumferential side of the intermediate transfer belt 9, facing the respective photosensitive drums 4, for primarily transferring the toner images formed on the respective photosensitive drums 4 onto the intermediate transfer belt 9. Here, the formation of each color toner image on each photosensitive drum 4 and the primary transfer of the toner images onto the intermediate transfer belt 9 will be described. 1, each photosensitive drum 4 is rotated clockwise, and each surface is irradiated with discharging light from a discharging device to initialize the surface potential of each photosensitive drum 4. The initialized surface potential of each photosensitive drum 4 is uniformly charged to a predetermined polarity (negative polarity in this embodiment) by each charging device 5. A laser beam emitted from an optical unit 8 is irradiated onto the charged surface of each photosensitive drum 4, and an electrostatic latent image corresponding to each color image is formed on the surface of each photosensitive drum 4.

[0010] The electrostatic latent image formed on each photosensitive drum 4 is visualized as a toner image by each developing device 6. Meanwhile, a transfer voltage of the opposite polarity (positive polarity in this embodiment) to the toner image formed on each photosensitive drum 4 is applied to each primary transfer roller 11. This forms a transfer electric field between each photosensitive drum 4 and its corresponding primary transfer roller 11, and each color toner image on each photosensitive drum 4 is electrostatically transferred onto the intermediate transfer belt 9. At this time, each color toner image is superimposed and transferred onto the intermediate transfer belt 9 to form a full-color toner image on the intermediate transfer belt 9, and the intermediate transfer belt 9 functions as an image carrier that carries the image on its surface. After each color toner image has been transferred onto the intermediate transfer belt 9, the photosensitive drum 4 has any residual toner adhering to its surface removed by each photosensitive cleaning device 7, preparing it for new image formation.

[0011] A secondary transfer roller 12 is provided downstream of the primary transfer roller 11K in the running direction of the intermediate transfer belt 9, and performs a secondary transfer of the toner image, which has been primarily transferred onto the intermediate transfer belt 9, onto the transfer sheet S. The secondary transfer opposing roller 20 and the secondary transfer roller 12 come into contact with each other via the intermediate transfer belt 9, forming a secondary transfer nip. A predetermined transfer voltage is applied to the secondary transfer roller 12, and the toner image formed on the intermediate transfer belt 9 is thereby secondarily transferred onto the transfer sheet S. Furthermore, a belt cleaning device 13 is provided upstream of the primary transfer roller 11Y in the running direction of the intermediate transfer belt 9, and removes residual toner remaining on the intermediate transfer belt 9 after image transfer. The intermediate transfer unit 10, the primary transfer rollers 11, the secondary transfer roller 12, and the belt cleaning device 13 described above form a transfer device 40. Above the secondary transfer roller 12, a fixing device 14 is arranged, which has a heating roller and a pressure roller, and fixes the toner image secondarily transferred onto the transfer sheet S.

[0012] A paper feed unit 15 is disposed at the bottom of the device main body 2. The paper feed unit 15 has a paper feed cassette 16, a paper feed roller 17, and a pair of registration rollers 18, and the transfer sheet S stored in the paper feed cassette 16 is fed by the paper feed roller 17 toward the pair of registration rollers 18. The pair of registration rollers 18 feeds the transfer sheet S toward the secondary transfer nip portion where the secondary transfer roller 12 and the intermediate transfer belt 9 come into contact with each other at a predetermined timing when the toner image formed on the intermediate transfer belt 9 matches a predetermined position on the transfer sheet S. At the top of the apparatus main body 2, toner bottles 19Y, 19C, 19M, and 19K are arranged, each containing a corresponding color toner to be supplied to each developing device 6.

[0013] When a full-color toner image is formed on the intermediate transfer belt 9, a transfer sheet S in a paper feed cassette 16 is separated and fed by the operation of a paper feed roller 17 in the paper feed unit 15. The fed transfer sheet S is sent to the secondary transfer nip at a predetermined timing by the operation of a pair of registration rollers 18. The transfer sheet S, onto which the full-color toner image formed on the intermediate transfer belt 9 is transferred at the secondary transfer nip, is sent to the fixing device 14, where the transferred image is fixed, and then discharged onto a paper discharge tray 28 formed on the upper part of the device main body 2 by a pair of discharge rollers 27 located downstream of the fixing device 14 in the sheet conveyance direction. As with each photosensitive drum 4, residual toner remaining on the intermediate transfer belt 9 is cleaned by a belt cleaning device 13. A predetermined amount of each color toner contained in each toner bottle 19 is replenished to the corresponding developing device 6 as needed via a toner conveyance path (not shown).

[0014] In conventional image forming apparatuses including color copier 1, endless belts similar to intermediate transfer belt 9 are used as latent image carriers, intermediate transfer bodies, recording medium transport members, fixing members, etc. Such endless belts are configured to run while being stretched over at least two rollers, but there is a problem in that the belt can deviate in a direction perpendicular to the running direction, which is known as belt deviation, due to the influence of the belt material, the precision of related parts, and deterioration of parts over time. Belt deviation can cause problems such as misalignment of the transferred image relative to the recording medium and belt damage due to the belt coming off the supporting rotor, so it was necessary to eliminate belt deviation. Therefore, conventional image forming apparatuses are provided with a belt deviation prevention means for eliminating belt deviation when it occurs. The configuration of the conventional belt deviation prevention means will be described below.

[0015] 2 is a schematic diagram of the belt deviation prevention means 23 provided in the intermediate transfer unit 10 with the belt cleaning device 13 removed, and FIG. 3 is a schematic cross-sectional view enlarging the right end of the belt deviation prevention means 23 along the line AA shown in FIG. 2. The belt deviation prevention means 23 used in this embodiment is configured in the same manner as the belt position correction mechanism 50 disclosed in, for example, the aforementioned "Patent Document 1" (JP 2017-58651 A). That is, the belt deviation prevention means 23 is configured with a shaft tilting mechanism that tilts the rotation shaft of the tension roller 21, which is one of the support rollers that supports the intermediate transfer belt 9, to limit the belt deviation range of the intermediate transfer belt 9 within a predetermined range.

[0016] 3, tension roller 21 has tension roller shaft 21a, which is integral with its end and serves as a rotation shaft coaxial with its own rotation center 21b. Tension roller shaft 21a has a cylindrical shape with a diameter shorter than that of tension roller 12, and is joined to tension roller 21. Belt deviation prevention means 23 includes, in order from the inside of the device along tension roller shaft 21a, a belt abutment member 24, a shaft tilting member 25 serving as a support rotor displacement member, a frame 26, and a roller shaft support member 29.

[0017] The tension roller shaft 21a passes through each of the above-mentioned members 24, 25, 26, and 29, and both ends of the tension roller shaft 21a are supported by roller shaft support members 29 via bearing members 30, which serve as support members. The belt abutment member 24 and shaft tilting member 25 are configured to be movable in the axial direction relative to the tension roller shaft 21a, and are configured to displace together with the tension roller shaft 21a in a direction perpendicular to the axial direction, i.e., in the direction in which the shaft end of the tension roller shaft 21a moves up and down in Figure 3.

[0018] Frame 26, made of a plate material, is fixed to device body 2 so as not to move even if tension roller shaft 21a, belt abutment member 24, and shaft inclination member 25 are displaced together. Frame 26 is provided with spring fixing portion 26a on its upper surface that protrudes toward the outside of the device, and below that is provided support member rotation shaft 31 that protrudes toward the outside of the device. The frame 26 is provided with an opening 26b through which the tension roller shaft 21a and an inclined portion rotation-preventing member 37 (described later) pass. The tension roller shaft 21a and the inclined portion rotation-preventing member 37 are displaced in a direction perpendicular to the rotation center 21b by the biasing force of a tension spring 33 (described later) and the resisting force thereof, and the biasing force of a biasing spring 32 (described later) and the resisting force thereof. The opening 26b is formed so that the tension roller shaft 21a, the inclined portion rotation-preventing member 37, and the frame 26 do not interfere with each other even when such displacement occurs.

[0019] The support member rotation shaft 31 supports the roller shaft support member 29 relative to the frame 26 so that it can rotate freely in the direction of arrow B shown in Figure 2. One end of a biasing spring 32 made of a tension coil spring that applies a biasing force to the roller shaft support member 29 is fixed to the spring fixing portion 26a. The other end of the biasing spring 32 is fixed to a spring fixing portion 29a that is provided integrally with the roller shaft support member 29.

[0020] Two roller shaft support members 29, arranged on both ends of the tension roller shaft 21a, are rotatably supported by support member rotation shafts 31 fixed to the respective frames 26, and are biased by biasing springs 32 in a clockwise direction in Figure 2 around the support member rotation shafts 31. When the roller shaft support members 29 rotate around the support member rotation shafts 31, the axial end of the tension roller shaft 21a, which is supported by the roller shaft support members 29 via the bearing members 30, is displaced up and down in Figures 2 and 3.

[0021] Each of the two roller shaft support members 29 has a slide slot 29b, which is a rectangular hole, provided approximately in the center thereof, and each slide slot 29b supports each bearing member 30 so that it can move radially around the tension roller shaft 21a, as indicated by arrow C in Figure 2. A tension spring 33 made of a compression coil spring is provided inside the slide slot 29b, and applies a biasing force to the bearing member 30 that acts outward from the rotation center of the roller shaft support member 29. With this configuration, the tension roller 21 is constantly subjected to a force from the biasing force of the tension spring 33 in a direction away from the secondary transfer opposing roller 20, allowing a predetermined tension to be applied to the intermediate transfer belt 9.

[0022] 3, a belt abutment member 24 and a shaft inclined member 25 disposed on the outer side of the device are provided on the tension roller shaft 21a between the tension roller 21 and the bearing member 30. The belt abutment member 24 has a cylindrical portion 24a with a smaller outer diameter than the tension roller 21, and a flange portion 24b with a larger outer diameter than the tension roller 21, disposed on the outer side of the device from the cylindrical portion 24a. If the intermediate transfer belt 9 shifts toward the outer side of the device, the end of the intermediate transfer belt 9 will come into contact with the inner surface of the flange portion 24b.

[0023] Shaft tilting member 25 has an upper inclined surface 25a that is inclined relative to tension roller shaft 21a, a stopper surface 25b that is provided to connect to the lower part of inclined surface 25a, and a positioning portion 25c that is provided on the upper part of inclined surface 25a and that secures presser member holder 36 (described later). Inclined surface 25a is configured as a curved surface that is formed to form part of the circumferential surface of a cone centered on rotation center 21b when shaft tilting member 25 is assembled to tension roller shaft 21a. Stopper surface 25b is configured as a curved surface that is formed to form part of the circumferential surface of a cylinder centered on rotation center 21b. In this embodiment, the inclination of the inclined surface 25a with respect to the rotation center 21b is 30°, but the inclination is not limited to this. The shaft inclination member 25 is configured not to rotate around the tension roller shaft 21a by the inclined portion rotation prevention member 37 described later.

[0024] After the end of the intermediate transfer belt 9 abuts against the inner surface of the flange portion 24b, the abutting end of the intermediate transfer belt 9 moves further toward the outside of the device. This movement causes the belt abutment member 24 and the shaft tilting member 25 to move toward the outside of the device on the tension roller shaft 21a. At this time, restricting members 34 that restrict the tension roller 21 and tension roller shaft 21a from moving axially outward are provided on the outside of each bearing member 30. The restricting members 34, each made of an E-ring, are positioned close to the outside of the bearing member 30 and are fixed so as to prevent axial movement relative to the tension roller shaft 21a while allowing the tension roller shaft 21a to rotate freely.

[0025] Frame 26 has guide portion 26c, which functions as a guide member and protrudes toward the inside of the device. Guide portion 26 has a contact portion 26d, which has a curved surface and contacts inclined surface 25a, at its lower corner, and a stopper surface 26e, which is formed on its lower surface. As shown in FIG. 3, in the initial state where the end of intermediate transfer belt 9 is not in contact with the inner surface of flange portion 24b, contact portion 26d contacts the lower end of inclined surface 25a, and stopper surface 26e contacts stopper surface 25b, thereby positioning shaft tilting member 25. This configuration allows stopper surface 25b to function as a positioning portion, and the inclination of tension roller 21 with respect to rotation center 21b can be kept constant in the initial assembly state.

[0026] Next, the operation of the belt shift regulation means 23 will be described. When the secondary transfer opposing roller 20, which is a drive roller, is driven to rotate, the tension roller 21, which is a driven roller, starts to rotate as the intermediate transfer belt 9 travels. At this time, if the end or the vicinity of the end of the intermediate transfer belt 9 is in contact with the cylindrical portion 24a of the belt abutment member 24, the belt abutment member 24 also starts to rotate.

[0027] In the above-described state, if belt deviation occurs, in which the end of the intermediate transfer belt 9 moves toward the outside of the device due to the influence of the parallelism between the members, etc., the end of the intermediate transfer belt 9 comes into contact with the inner surface of the flange portion 24b. After this, if the intermediate transfer belt 9 moves further toward the outside of the device, the belt abutting member 24 with which the end of the intermediate transfer belt 9 is in contact moves toward the outside of the device, and the shaft inclination member 25 arranged outside the belt abutting member 24 moves toward the outside of the device following the movement of the belt abutting member 24.

[0028] As shown in Figure 3, contact portion 26d contacts inclined surface 25a, and the vicinity of the end of tension roller shaft 21a is supported by roller shaft support member 29 via bearing member 30. In addition, roller shaft support member 29 receives a biasing force from biasing spring 32 in a direction that causes it to rotate clockwise in Figure 2 around support member rotation axis 31, so tension roller shaft 21a receives a biasing force that moves upward in Figure 3.

[0029] When the end of the intermediate transfer belt 9 is not in contact with the inner surface of the flange portion 24b, the stopper surface 25b of the shaft inclination member 25, which attempts to move upward due to the biasing force of the biasing spring 32, hits the stopper surface 26e. Therefore, the contact position between the inclined surface 25a and the contact portion 26d is restricted at the position where the stopper surfaces 25b and 26e come into contact, and the positional relationship of the respective members is maintained with the contact portion 26d in contact with the lower end of the inclined surface 25a.

[0030] 3, as described above, when the intermediate transfer belt 9 receives a moving force in a direction toward the outside of the device, i.e., a moving force in a direction toward the right in FIG. 3, the end of the intermediate transfer belt 9 comes into contact with the inner surface of the flange portion 24b. When the intermediate transfer belt 9 receives a further moving force in a direction toward the outside of the device from this state, the belt abutment member 24 and the shaft inclination member 25 move toward the outside of the device along the tension roller shaft 21a.

[0031] At this time, contact portion 26d moves relatively along inclined surface 25a, and as a result, the contact position between inclined surface 25a and contact portion 26d tends to be displaced upward on inclined surface 25a. As a result, the end of tension roller shaft 21a in the direction in which intermediate transfer belt 9 moves due to the belt shift is pushed down against the upward biasing force of biasing spring 32. On the other hand, the end of the intermediate transfer belt 9 on the opposite side to the direction of movement due to the belt shift is not in contact with the inner surface of the flange portion 24b. Therefore, the end of the tension roller shaft 21a on the opposite side to the direction of movement of the intermediate transfer belt 9 is held in a state where the contact portion 26d is in contact with the lower end of the inclined surface 25a, similar to the state shown in FIG.

[0032] As a result, the end of the tension roller shaft 21a in the direction in which the intermediate transfer belt 9 moves is pressed down relative to the other end, and the tension roller shaft 21a is tilted downward in FIG. In this way, as the tension roller shaft 21a tilts, the speed at which the intermediate transfer belt 9 moves toward the outside of the device gradually slows, and eventually the intermediate transfer belt 9 starts to move toward the inside of the device. As a result, the position of the end of the intermediate transfer belt 9 is gradually returned, and the intermediate transfer belt 9 can run stably at a position where the belt deviation converges. This is also true when the belt deviation of the intermediate transfer belt 9 occurs in the opposite direction. The principle by which the intermediate transfer belt 9 can be returned to its original position by tilting the tension roller shaft 21a is disclosed in, for example, the above-mentioned "Patent Document 1" (JP 2017-58651 A).

[0033] The belt deviation prevention unit 23 has a presser member 35 that faces the outer peripheral surface of the intermediate transfer belt 9 near the end of the intermediate transfer belt 9 wound around the tension roller 21. When viewed from the axial direction of the rotation center 21b, the presser member 35 has a gate-like shape with an open bottom. The presser member 35 is fixed to the shaft tilting member 25 via a presser member holder 36. The shaft tilting member 25 also moves up and down in conjunction with the displacement of the tension roller shaft 21a. Therefore, when the tension roller shaft 21a moves up and down due to the belt deviation of the intermediate transfer belt 9, the presser member 35 fixed to the shaft tilting member 25 also moves up and down. As a result, the presser member 35 can constantly press down on the surface of the end of the intermediate transfer belt 9 that is stretched between the tension roller shaft 21a and the driven tension roller 21, and deformation of the end of the intermediate transfer belt 9 can be constantly suppressed.

[0034] The pressing member 35 has a configuration in which a foam layer 35a made of a foamed material with a cellular structure is attached to a pressing member holder 36, and a surface layer 35b made of a low-sliding material that comes into contact with the outer circumferential surface of the intermediate transfer belt 9 is joined below the foam layer 35a. Any material may be used to form the foam layer 35a and the surface layer 35b, as long as it suppresses deformation of the intermediate transfer belt 9 and does not damage the surface of the intermediate transfer belt 9. The pressing member 35 is configured so that the end face facing the outside of the device comes into contact with the inner surface of the flange portion 24 b. As a result, when the end face of the intermediate transfer belt 9 is in contact with the inner surface of the flange portion 24 b, the end of the intermediate transfer belt 9 can be constantly pressed by the pressing member 35.

[0035] The pressing member holder 36 has a fitting hole 36a into which the positioning portion 25c is fitted, and two claw portions 36b that engage with the bottom surface of the shaft tilting member 25. The pressing member holder 36 is detachably attached to the shaft tilting member 25 by expanding the open lower portion so that each of the claw portions 36b moves in the direction of the paper surface of FIG. 3, fitting the positioning portion 25c into the fitting hole 36a, and then closing the expanded lower portion so that each of the claw portions 36b engages with the bottom surface of the shaft tilting member 25.

[0036] In the belt deviation prevention device 23 described above, when the intermediate transfer belt 9 deviates, the belt abutment member 24 and the shaft tilting member 25 move toward the outside of the device in response to the movement of the end of the intermediate transfer belt 9. At this time, the shaft tilting member 25 moves so that the slope 25a is aligned with the abutting portion 26d, tilting the tension roller 21, and the presser member 35 also tilts in conjunction with this. This makes it possible to prevent deformation and damage to the end of the intermediate transfer belt 9 even in a device that tilts the tension roller 21 to prevent belt deviation. Furthermore, by attaching the presser member holder 36 that holds the presser member 35 to the shaft tilting member 25, the member for attaching the presser member holder 36 to the tension roller shaft 21a can be omitted, thereby saving space.

[0037] Next, the tilt portion rotation prevention member 37 that prevents the shaft tilting member 25 from rotating around the tension roller shaft 21a will be described. The tilt portion rotation prevention member 37 covers the shaft tilting member 25 along the side and bottom surfaces of the shaft tilting member 25. It has a gate-like shape with an open top when viewed from the axial direction, and is integrated with the bearing member 30. Therefore, even if a rotational force acts on the shaft tilting member 25 due to the rotation of the tension roller 21 and tension roller shaft 21a, the shaft tilting member 25 is prevented from rotating. The tilt portion rotation prevention member 37 does not have any portions that contact both axial ends of the shaft tilting member 25, and is shaped so as not to prevent the shaft tilting member 25 from moving axially on the tension roller shaft 21a. As a result, when the intermediate transfer belt 9 shifts as described above, the shaft tilting member 25 can move axially without rotating around the tension roller shaft 21a.

[0038] Because inclined portion rotation preventing member 37 is joined to bearing member 30, it moves together with tension roller shaft 21a in the sliding direction of bearing member 30 indicated by arrow C in Figure 2. Furthermore, because bearing member 30 to which inclined portion rotation preventing member 37 is joined is supported by roller shaft support member 29, when roller shaft support member 29 rotates in the direction indicated by arrow B in Figure 2 and the tension roller shaft 21a is displaced up and down, inclined portion rotation preventing member 37 also displaces up and down together with tension roller shaft 21a.

[0039] Here, the problems with the belt deviation regulating means 23 described above will be explained. In the belt deviation prevention means 23, when the intermediate transfer belt 9 deviates from the belt, the belt abutment member 24 and the shaft tilting member 25 move toward the outside of the device as the end of the intermediate transfer belt 9 moves. When this movement displaces the slope 25a toward the outside of the device, the frame 26 having the abutment portion 26d in contact with the slope 25a displaces the tension roller 21, tension roller shaft 21a, belt abutment member 24, and shaft tilting member 25 downward. This displacement controls the movement of the end of the intermediate transfer belt 9, eliminates the belt deviation of the intermediate transfer belt 9, and displaces the members 21, 21a, 24, and 25 upward.

[0040] During the above-described operation, each of the members 21, 21a, 24, and 25 is displaced up and down, and at this time, the bearing member 30 and the regulating member 34 are also displaced up and down in accordance with the displacement of the tension roller shaft 21a. Here, the regulating member 34 does not move axially relative to the tension roller shaft 21a, but the bearing member 30 moves axially relative to the tension roller 21a. As a result, the bearing member 30 and the regulating member 34 come into contact with each other and slide, causing friction and wear between the bearing member 30 and the regulating member 34, which can reduce the axial positioning accuracy of the tension roller 21. The configuration of the present invention that solves the above-mentioned problems will be described below.

[0041] FIG. 4 is a schematic diagram of a belt deviation control means 38 according to one embodiment of the present invention, which is provided in the intermediate transfer unit 10 with the belt cleaning device 13 removed, and FIG. 5 is a schematic cross-sectional view showing an enlarged view of the right end of the belt deviation control means 38 in the DD cross section shown in FIG. 4. As shown in Figures 4 and 5, the belt shift regulation means 38 used in this embodiment differs from the conventional belt shift regulation means 23 described above only in that it has an intermediate member 39 between the bearing member 30 and the regulation member 34, and the other configurations are the same.

[0042] Intermediate member 39 has the same circular outer shape as regulating member 34, but is formed to be slightly smaller than regulating member 34. Intermediate member 39 also has a hole through which tension roller shaft 21a passes, and this hole has a diameter larger than that of tension roller shaft 21a. Intermediate member 39 is made of an elastically deformable member made of a resin material, rubber, or the like, and is provided between the surface of bearing member 30 facing outward from the apparatus and the surface of regulating member 34 facing inward from the apparatus. Intermediate member 39 is sandwiched between bearing member 30 and regulating member 34 with its hole not in contact with tension roller shaft 21a, and is disposed in a state where it is slightly elastically deformed by members 30, 34.

[0043] The above-described configuration of this embodiment provides the following advantages. When the intermediate transfer belt 9 shifts, the tension roller shaft 21a is displaced due to the action of the belt shift prevention device 38, causing the members 30 and 34 to move vertically. This results in a difference in the relative movement between the members 30 and 34. The elastically deformable intermediate member 39 provided between the members 30 and 34 absorbs the difference in movement between the members 30 and 34 through its elastic deformation. This prevents unexpected friction and wear between the members 30 and 34 due to direct sliding between the members 30 and 34, and prevents a decrease in the axial positioning accuracy of the tension roller 21 and tension roller shaft 21a. As a result, an intermediate transfer unit 10, a transfer device 40, and an image forming apparatus 1 using the same can be provided that can effectively control belt shift over a long period of time, even when an external force acts in the axial direction on the tension roller 21, which controls belt shift.

[0044] Furthermore, because the intermediate member 39 is elastically deformable, even if differences in the amount of movement occur between the members 30 and 34, unexpected friction and wear are prevented between the intermediate member 39 and the members 30 and 34, and a decrease in the axial positioning accuracy of the tension roller 21 and tension roller shaft 21a is prevented. Furthermore, since the intermediate member 39 is configured not to rotate following the rotation of the tension roller 21 and tension roller shaft 21a, unexpected friction and wear between the intermediate member 39 and the members 30 and 34 is further prevented. Furthermore, by forming the intermediate member 39 from a resin material, the weight of the device can be reduced, the operability of the device can be improved, the life of the device can be extended, and costs can be reduced.

[0045] While the preferred embodiments of the present invention have been described above, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the spirit and scope of the present invention as defined in the claims unless otherwise specifically limited in the above description. For example, while the intermediate transfer belt 9 is shown as a belt member in the above embodiment, the belt member to which the present invention is applicable is not limited to this, and the present invention is applicable to any belt as long as it is stretched over multiple support rotors and runs in conjunction with the rotation of the multiple support rotors. Furthermore, although the belt shift control means 38 shown in the above embodiment is configured to have a pressure member 35 and a pressure member holder 36, a belt shift control means to which the present invention can be applied does not have to have a pressure member 35 and a pressure member holder 36. The effects described in the embodiments of the present invention are merely examples of the most preferable effects resulting from the present invention, and the effects of the present invention are not limited to those described in the embodiments of the present invention. [Explanation of symbols]

[0046] 1. Image forming equipment (color copiers) 9 Belt member, image carrier (intermediate transfer belt) 10 Belt unit (intermediate transfer unit) 20 Supporting rotor (secondary transfer opposing roller) 21 Supporting rotor, first supporting rotor (tension roller) 21a Rotating shaft (tension roller shaft) 22 Supporting rotor (entrance roller) 24 Belt stopper 25 Support rotor displacement member (axis tilt member) 25a slope 26c Guide member (guide part) 30 Support member (bearing member) 34 Regulatory components 39 Intermediate parts 40 Transcription device [Prior art documents] [Patent documents]

[0047] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-58651 [Patent Document 2] Patent No. 6691682 [Patent Document 3] Patent No. 6628141

Claims

1. a belt member that is stretched over a plurality of supporting rotors and is driven by the rotation of the plurality of supporting rotors; a belt abutment member that is provided on a rotation shaft of a first support rotor that is one of the plurality of support rotors, the belt abutment member contacting the end of the belt member when the end of the belt member moves in the axial direction of the rotation shaft and that is movable in the axial direction together with the belt member; a support rotor displacement member provided on the rotation shaft and movable in the axial direction in response to movement of the belt abutment member, the support rotor displacement member having an inclined surface for displacing the first support rotor; a guide member that comes into contact with the inclined surface to regulate the moving direction of the support rotor displacement member; a support member that rotatably supports the first support rotor and the rotation shaft; a restricting member that restricts movement of the first support rotor and the rotary shaft in the axial direction; an intermediate member that is provided between the support member and the regulating member in the axial direction, and that forms contact surfaces with both a surface of the support member and a surface of the regulating member and elastically deforms to prevent friction between the support member and the regulating member; A belt unit having

2. 2. The belt unit according to claim 1, The belt unit according to claim 1, wherein the regulating member is rotatable together with the rotary shaft, and the intermediate member is in contact with the rotating regulating member so as to be elastically deformable.

3. 3. The belt unit according to claim 1, The belt unit is characterized in that the intermediate member is configured not to rotate in response to rotation of the first support rotor and the rotary shaft.

4. 4. The belt unit according to claim 1, The belt unit is characterized in that the intermediate member is made of a resin material.

5. 5. A transfer device comprising the belt unit according to claim 1.

6. An image forming apparatus comprising a belt unit according to any one of claims 1 to 4.

7. An image forming apparatus comprising the transfer device described in claim 5.

8. In the image forming apparatus according to claim 6 or 7, The image forming apparatus is characterized in that the belt member is used as an image carrier that carries an image on its surface, and a transfer roller is disposed opposite the belt unit.

Images