JP2005035722A - Belt drive device, image formation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a belt drive device for always traveling a belt at a constant position without deteriorating a performance for conveying a sheet such as transfer sheet and the like to be fundamentally performed in a belt drive device for preventing the belt from deviating and meandering in a sheet conveying device, a transferring device, and the like provided to an image formation device and the like. <P>SOLUTION: Ribs X4-1, X4-2 formed on surfaces of drive rollers sequentially delivering a belt are rotated in a counterclockwise direction seen in a direction of an arrow X5 respectively, so that a conveying action of a spring acts on the belt by the spiral ribs X4-1 and X4-2. As a result, the belt always travels at a central part of the drive rollers without lateral displacement in only one direction, so as to adjust a traveling position of the belt. Furthermore, because the drive rollers are not shaped like a crown, such a problem for deteriorating a conveying performance due to a spacing between the belt and the sheet to be conveyed can be avoided. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a belt driving device for preventing belt deviation and meandering, and more particularly to a belt driving device capable of simultaneously improving conveyance performance and belt meandering and deviation, and further to an image forming apparatus. The present invention relates to a belt driving device that can be suitably applied to a sheet conveying device, a transfer device, and the like included in the above.

  Generally, the conveyance of a sheet such as a document or transfer paper by a document conveying device or a transfer device provided in an image forming apparatus configured as a copying machine, a printer, a facsimile, or a complex machine thereof is composed of a rubber member, a plastic member, or the like. Many belt-driven transport devices that use belts are used. The belt travel in this belt drive type conveying device (hereinafter referred to as a belt drive device) is generally made up of a drive roller that sequentially feeds the belt and a driven roller that rotates in the same direction as the drive roller according to the rotation of the drive roller. And is done by the rotational force.

  However, when the driving roller or the driven roller rotates during conveyance of a sheet such as transfer paper using a belt driving device, a problem such as deviation or meandering occurs in the running belt. There is a problem that the paper transport position is not fixed, and the output image is distorted, or color misregistration occurs in color printing.

  In addition, not only relatively hard sheets such as plain paper and OHP paper but also soft materials such as cloth are used as the output destination of images. The stability with respect to the conveyance of image output objects such as sheets and fabrics is further demanded. In response to this, in recent years, there is a need for a belt driving device for the purpose of preventing the deviation and meandering of a running belt.

As a prior art of the belt driving device described above, for example, as disclosed in Patent Document 1, a roller that forwards only the fabric is provided separately from the roller that directly participates in the rotation of the belt that sequentially feeds the fabric that is an image output object. A belt driving device has been proposed in which a roller is provided with a function of preventing problems such as distortion of the fabric, meandering, and wrinkles.
This belt drive device is provided with a spiral rib on the roller surface that spreads from the center of the roller that forwards the fabric toward both ends of the roller, thereby preventing problems such as distortion, meandering, and wrinkling of the fabric. Yes. In other words, the tension that pulls the fabric left and right by the screw carrying action of the spiral rib that spreads from the center of the roller to the both ends of the roller, which is generated by the rotation of the roller (that is, the rib rotates). This prevents the occurrence of problems such as distortion, meandering, and wrinkling of the fabric.

  Further, Patent Document 1 also discloses a belt driving device in which the shape of the roller is a so-called crown shape in which the diameter of the central portion of the roller is larger than the diameter of the end portion. In this belt drive device, the running of the fabric is stabilized by the self-aligning action which acts on the belt by making the shape of the roller crown.

Further, in addition to the belt driving device disclosed in Patent Document 1, a high friction member is provided on the outer peripheral surface of a driving roller having a comb-like shape as described in Patent Document 2, for example. A belt driving device having a crown shape has also been proposed.
In this belt drive device, the belt is prevented from being laterally displaced by providing a high friction member, and the drive roller has a crown shape. Stabilizing direction. It is also shown that this belt drive device can use a belt having a low friction coefficient such as a plastic member by providing a high friction member.

JP 2002-249976 A Japanese Utility Model Publication No. 6-18349

  However, in the case of the belt driving device in which a spiral rib is formed on the roller surface as in the above-mentioned Patent Document 1, since the tension works from the central part of the roller to both ends, for example, one of the belts If the tension acting in the end direction becomes greater than the tension acting in the other end direction, the belt will be laterally displaced in the direction in which the greater tension is exerted. For this reason, the belt is laterally displaced only in one direction, and the belt may eventually fall off the roller.

  In order to solve such a problem, as described in Patent Document 1 and Patent Document 2 described above, when the shape of the roller is a crown shape, the centering of the roller is always performed by the automatic centering action that acts on the belt. Since the belt tries to move in the direction, the belt is almost prevented from falling off the roller. However, since the roller has a crown shape, the belt stretched around the roller naturally has a shape in which the central portion of the belt is more convex than the end portion of the belt along the shape of the roller. It will be. Therefore, when a sheet such as transfer paper is placed on the belt, a slight gap is formed between the belt and the sheet, and the conveyance performance for the sheet may be deteriorated.

  Therefore, the present invention has been made in view of the above circumstances, and its object is to allow the belt to always travel at a certain position without deteriorating the conveyance performance that the belt should originally perform. is there.

  In order to achieve the above object, the present invention provides a belt drive device for driving an endless belt stretched around a plurality of rollers, wherein at least one of the rollers moves the belt by means of a screw carrying action. The belt driving device is formed by forming a spiral groove or projection on the surface of the roller.

  The present invention is also directed to a belt driving device for driving an endless belt stretched around a plurality of rollers, wherein at least one of the rollers is connected to one end of the roller by a screw carrying action. Helical grooves or protrusions that are conveyed in the direction of the part and provided at the end of the roller for preventing the belt from slipping when the belt is brought into contact with the belt when the belt is conveyed by the spiral grooves or protrusions. It is also configured as a belt drive device provided with a flange member.

  Furthermore, the present invention provides a belt driving device for driving an endless belt stretched around a plurality of rollers, wherein at least one of the rollers moves the belt from the center of the roller by a screw carrying action. Spiral grooves or protrusions in the direction of transporting to both ends of the roller are formed on the surface near the center of the roller, and spiral grooves or protrusions in the direction of transporting the belt toward the center of the roller by the carrying action of the screws. It is also configured as a belt driving device in which the protrusion is formed on the surface near the end of the roller.

  In this case, the interval between the spiral grooves or protrusions formed on the surface near the center of the roller may be wider or narrower than the interval between the spiral grooves or protrusions formed on the surface near the end of the roller. desirable.

  In addition, it is desirable that any of the belt driving devices described above is a sheet conveying belt device or a transfer belt device in the image forming apparatus.

As described above, the present invention provides a belt driving device for driving an endless belt stretched around a plurality of rollers, wherein at least one of the rollers moves the belt to a central portion of the roller by a screw carrying action. The belt driving device is formed by forming spiral grooves or projections in the direction on the surface of the roller.
As a result, a force to carry the belt from both ends of the roller toward the central portion of the roller works, so that the belt does not cause lateral displacement only in one direction, and the belt always runs in the central portion of the roller. Therefore, the running of the belt is stabilized. Further, since the roller does not have a crown shape, there is provided a belt driving device that does not have a problem of deterioration in conveying performance due to a gap formed between the belt and the conveyed sheet.

The present invention is also directed to a belt driving device for driving an endless belt stretched around a plurality of rollers, wherein at least one of the rollers is connected to one end of the roller by a screw carrying action. Helical grooves or protrusions that are conveyed in the direction of the part and provided at the end of the roller for preventing the belt from slipping when the belt is brought into contact with the belt when the belt is conveyed by the spiral grooves or protrusions. It is also configured as a belt drive device provided with a flange member.
As a result, a force for carrying the belt only in the direction of the one end of the roller acts, and the belt biased to the one end of the roller by the spiral groove or protrusion comes into contact with the flange member, so that the belt The running position of is stable. Of course, since the roller does not have a crown shape, the conveying performance of the belt does not deteriorate.

Furthermore, the present invention provides a belt driving device for driving an endless belt stretched around a plurality of rollers, wherein at least one of the rollers moves the belt from the center of the roller by a screw carrying action. Spiral grooves or protrusions in the direction of transporting to both ends of the roller are formed on the surface near the center of the roller, and spiral grooves or protrusions in the direction of transporting the belt toward the center of the roller by the carrying action of the screws. It is also configured as a belt driving device in which the protrusion is formed on the surface near the end of the roller.
As a result, a force to carry the belt from the central portion of the roller toward both ends of the roller is exerted, so that the belt is widened to prevent wrinkles and the belt is shifted toward the roller end portion. Even when the belt is moved, the belt is not displaced toward the end more than a certain extent by the spiral grooves or protrusions that exert the carrying action from the roller end to the center, and the belt running position is It stabilizes at. Of course, since the roller does not have a crown shape, the conveying performance of the belt does not deteriorate.

In this case, the interval between the spiral grooves or protrusions formed on the surface near the center of the roller may be wider or narrower than the interval between the spiral grooves or protrusions formed on the surface near the end of the roller. desirable.
As a result, the belt biased toward the end of the roller by the carrying action of the screw by the spiral groove or protrusion formed in the central portion of the roller causes the conveying force toward the central direction of the roller formed at the end. Due to the spiral grooves or protrusions exhibiting the above, it is not possible to move in the direction of the end more than a certain degree, and the vehicle travels at that position, and the traveling position is stabilized. Also in this case, since the roller does not have a crown shape, the belt conveyance performance does not deteriorate.

  In addition, any of the belt driving devices described above can be applied to a belt driving device in a sheet conveying belt device or a transfer belt device in an image forming apparatus.

Hereinafter, embodiments and examples of the present invention will be described with reference to the accompanying drawings for understanding of the present invention. It should be noted that the following embodiments and examples are examples embodying the present invention, and do not limit the technical scope of the present invention.
FIG. 1 is a schematic sectional view showing an image forming apparatus A according to an embodiment of the present invention (hereinafter referred to as an embodiment) including a sheet conveyance path, and FIG. 2 is a belt drive according to the embodiment. FIG. 3 is a perspective view showing an outline of the device B1, FIG. 3 is a view of the roller X provided in the belt driving device B1 according to the embodiment shown in FIG. 2, and FIG. 4 is a view of the roller X shown in FIG. FIG. 5 is a perspective view showing an outline of a belt drive device B2 according to another embodiment, FIG. 6 is a view showing a roller Y provided in the belt drive device B2 from the side, and FIG. FIG. 8 is a perspective view of the roller Y as viewed obliquely, FIG. 8 is a perspective view showing an outline of a belt driving device B3 according to another embodiment, and FIG. 9 is provided in the belt driving device B3 according to the embodiment. FIG. 10 is a view of the roller Z seen from the side, and FIG. 10 shows the roller Z obliquely. It is a perspective view from.

  First, an image forming apparatus A according to an embodiment of the present invention including a sheet conveyance path will be described with reference to FIG. Note that one of belt driving devices B1, B2, and B3, which will be described later, is used as a belt driving device used in the sheet conveying rollers R1 to R7 included in the image forming apparatus A or a belt device including a sheet conveying roller (not shown). One or more are applicable. The image forming apparatus A includes a printer 2 that performs image formation and printing, and a finisher 1 that performs post-processing on a sheet such as transfer paper after printing by the printer 2.

The printer 2 is provided with a sheet conveyance path 9 for feeding the sheet to the fixing device 7 via the transfer device 6 and conveying the sheet to the finisher 1. The sheet conveyance path 9 is switched between a normal discharge path 10 for discharging a sheet after image formation without using the finisher 1 and a post-processing discharge path 11 for discharging the sheet using the finisher 1. An external switching mechanism is provided. The printer 2 includes a paper feed tray 5 for feeding sheets, a transfer device 6 for transferring a toner image to the sheet, a fixing device 7 for fixing the toner image transferred to the sheet to the sheet, and a transferred sheet. It is composed of a paper discharge tray 8 for paper discharge.
The finisher 1 includes an inserter 3 for supplying insertion sheets such as thick paper, and a plurality of discharge trays 4 for receiving sheets discharged from the finisher 1 so as to be movable up and down. It consists of a tray 4a and the like.
The image forming apparatus A is only mentioned as an example of an image forming apparatus according to the present invention including a sheet conveyance path, and the image forming apparatus according to the present invention is a copying machine, a printer, a facsimile machine, or a complex machine thereof. There is no problem in any form as long as the image forming apparatus is configured.

Next, the operation in the sheet conveyance path such as transfer paper on which printing is performed by the printer 2 will be described in the case where the printed sheet is discharged to the normal discharge path 10.
When a user issues an instruction to start printing from a display input unit (not shown) such as a liquid crystal panel, a sheet is first supplied from the sheet feeding tray 5 by the sheet conveying roller R1. The sheet is conveyed to the transfer device 6 by a sheet conveyance path 9 provided with a sheet conveyance roller R2, and a toner image is transferred to the sheet by the transfer device 6. Thereafter, the sheet is conveyed to the fixing device 7 through the sheet conveying path 9, and a toner image is fixed on the sheet by a fixing roller having a heater and a pressure roller. The sheet on which the toner image is fixed is discharged to the paper discharge tray 8 via a normal discharge path 10 having a sheet conveying roller R3.

Further, a description will be given of a case where a printed sheet is discharged to the post-processing discharge path 11 with respect to a sheet conveyance path such as transfer paper on which printing is performed by the printer 2.
The sheet on which the toner image has been fixed by passing through the sheet conveying path 9 and passing through the fixing device 7 having a fixing roller and a pressure roller passes from the printer 2 to the finisher via the sheet discharge roller R4. 1 is taken into the post-processing discharge path 11 in the interior. Thereafter, the sheet is discharged to the movable discharge tray 4a via the sheet conveying rollers R6 and R7.
The insertion sheet previously placed on the inserter 3 passes through the sheet conveyance path 12 from the inserter 3 to the sheet conveyance roller R6 and is conveyed via the sheet conveyance roller R5. After passing through the sheet conveying rollers R6 and R7 in the same manner as the printed sheet, the sheet is discharged to the movable discharge tray 4 and inserted into the printed sheet.

  Hereinafter, in the image forming apparatus A, a sheet conveying belt provided between the transfer device 6 and the fixing device 7 in the sheet conveying path 9, a transfer paper used for a transfer belt provided in an image forming apparatus (not shown), etc. A belt driving device for guiding the sheet conveying belt or the transfer belt will be described with reference to FIGS.

First, the belt driving device B1 will be described with reference to FIGS.
The belt driving device B1 includes a cylindrical driving roller X that rotates the belt J, and a cylindrical driven roller W that rotates following the driving roller X. As shown in FIGS. 3 and 4, the surface of the driving roller X or the driven roller W (the driving roller X in the present embodiment) is arranged from the both ends of the driving roller X to the center of the driving roller X. A spiral screw-shaped rib X4 that expands toward the portion is formed so as to be axisymmetric (the interval between the left and right ribs is equal to the inclination) with respect to the center line of the drive roller X indicated by the arrow X1. That is, the rib X4 is formed in a direction in which the front rib X4-1 moves forward in the direction of the left screw when viewed in the axial direction of the driving roller X indicated by the arrow X5, and the rear rib X4-2. Is formed in a direction that advances forward in the direction of the right-hand thread.
Here, as shown in FIGS. 3 and 4, the rib X4 is interrupted near the center of the drive roller X, but may be connected at the center of the drive roller X.

  Since the ribs X4-1 and X4-2 are formed in the above-described direction, the driving roller X and the driven roller W are moved so that the belt J runs in the direction of the arrow X1 (that is, the above-described direction). By rotating each of them in the counterclockwise direction as viewed in the direction of the arrow X5, a screw carrying action is exerted on the belt J by the spiral ribs X4 (X4-1, X4-2). That is, as shown in FIG. 2, the forces X2 and X3 act on the belt J in the direction of the arrow perpendicular to X1 toward the center of the driving roller X, respectively.

Here, since the spiral of the rib X4 is line symmetric with respect to the X1, the force X2 and the force X3 have the same force. As a result, the belt J always travels in the central portion of the drive roller X without causing the lateral displacement of the belt J only in one direction (that is, because the self-aligning action works). Is adjusted.
Further, as shown in FIGS. 3 and 4, since the driving roller X does not have a crown shape, the problem of deterioration in conveying performance due to a gap formed between the belt J and the conveyed sheet is also avoided. Is done.

Next, the belt driving device B2 will be described with reference to FIGS.
The belt driving device B2 includes a cylindrical driving roller Y that rotationally drives the belt J, and a cylindrical driven roller W that rotates following the driving roller Y. The surface of the drive roller Y has a spiral shape in the direction in which the right screw advances as seen from the one end of the drive roller Y toward the other end of the drive roller Y in the roller axis direction indicated by the arrow Y5. The rib Y4 is formed. In addition, a flange-like flange member Y3 is provided at the other end of the drive roller Y so that the side surface of the belt J abuts when the belt J is carried and the belt J is prevented from being displaced. .

  The drive roller Y and the driven roller W are rotated so that the belt J runs in the direction of the arrow Y1, so that the screw J acts on the belt J by the spiral formed by the rib Y4. . That is, a force Y2 acts on the belt J in the direction of the arrow perpendicular to the arrow Y1 from one end of the drive roller Y to the other end of the drive roller Y.

  Thus, the running belt J moves in the direction of the arrow of the force Y2 and stops at a position where the side surface of the belt J abuts on the flange member Y3. That is, the running position of the belt J is determined. Further, as shown in FIGS. 6 and 7, in order to position the belt J, it is not necessary to form the driving roller Y in a crown shape, so that there is a gap between the belt J and the conveyed sheet. The problem of a decrease in conveyance performance due to being able to be avoided is also avoided.

Further, the belt driving device B3 will be described with reference to FIGS.
As in the other embodiments, the belt driving device B3 includes a cylindrical driving roller Z that rotates the belt J, and a cylindrical driven roller W that rotates following the driving roller Z. . On the surface of the driving roller Z, there are two spiral ribs Z4-1 and Z4-2 extending from both ends of the driving roller Z toward the center of the driving roller Z, and the ribs Z4-1 and Z4-2. The ribs Z4-3 and Z4-4 provided on the outer side, that is, on the end side are formed. The four ribs are collectively referred to as a rib Z4. The ribs Z4-1 and Z4-2, and the ribs Z4-3 and Z4-4 are symmetrical with respect to the center portion of the driving roller Z indicated by the arrow Z1 (the interval between the left and right ribs is equal to the inclination). It is formed to become.

  The spiral winding directions of the ribs Z4-1 and Z4-2 are both counterclockwise when the belt J runs in the direction of the arrow Z1, that is, when the driving roller Z is viewed from the direction indicated by the arrow Z5. When the belt rotates, the screw feeding action in the direction of pulling the belt J in the direction of the end of the driving roller Z works. Therefore, the rib Z4-1 is spirally wound in the direction of the right screw as viewed in the roller axis direction indicated by the arrow Z5, and the rear rib Z4-2 is leftward as viewed in the arrow Z direction. It is wound in the direction that the screw advances.

  The spiral winding directions of the ribs Z4-3 and Z4-4 are both when the belt J runs in the direction of the arrow Z1, that is, when the driving roller Z is viewed from the direction indicated by the arrow Z5. When the belt rotates in the counterclockwise direction, the screw feeding action in the direction of pulling the belt J in the direction of the central portion of the driving roller Z works. Accordingly, the rib Z4-3 is spirally wound in the direction of the left screw as viewed in the roller axial direction indicated by the arrow Z5, and the rib Z4-4 on the back side is viewed in the arrow Z direction. It is wound in the direction that the right screw advances.

Here, the interval (pitch) of the ribs Z4 in the roller axis direction is greater than that of the ribs Z4-1 and Z4-2 near the center of the drive roller Z as shown in FIGS. The Z4-3 and Z4-4, which are ribs near both ends of the driving roller Z, are denser. However, in some cases, the ribs Z4-3 and Z4-4 near both ends of the drive roller Z are rougher than the ribs Z4-1 and Z4-2 near the center of the drive roller Z. You may form so that it may become.
In short, the density of the screw spacing may be set so that the screw carrying force is larger at both ends than at the center. Moreover, although each said rib is interrupted in each edge part, you may connect in each edge part.

In this embodiment, the driving roller Z and the driven roller W are rotated so that the belt travels in the direction of the arrow Z1, so that the spiral in the direction formed by the ribs Z4-1 and Z4-2 is applied. , The screw carrying action works in the direction to spread the belt in the direction of both ends. For this reason, it is conceivable that the belt J may be displaced toward one of the end portions in some cases, and if it is left as it is, the belt may be detached from the shaft end of the roller Z as in the conventional belt driving device. . On the other hand, as described above, the rib Z4-3 and the rib Z4-4 in the direction of carrying the belt J toward the center of the roller J are formed on the shaft end side, and the rib Z4- on the end side is formed. 3 and the rib Z4-4 are adjusted so that the screw carrying action is larger than the screw carrying action by the central rib Z4-1 or Z4-2. Therefore, the belt J is pushed back toward the central portion of the driving roller Z by any one of these ribs, and the position of the belt J is the position where the pushing force toward the end portion and the pushing force toward the central portion are balanced. The centering action of being decided will work, and the running position of the belt will be stabilized.
Further, as shown in FIGS. 9 and 10, since the driving roller Z does not have a crown shape, the problem of deterioration in conveying performance due to a gap between the belt and the conveyed sheet can be avoided. The

  In each embodiment, the force generated by the screwing action is applied to the belt by the spiral rib formed on the surface of each of the driving rollers X, Y, Z of the cylindrical body rotating the belt. However, any shape may be used as long as it does not have a spiral rib but can carry a screw. In each embodiment, the spiral rib is formed on the surface of each of the driving rollers X, Y, and Z, but may be formed on the surface of the driven roller W.

1 is a schematic cross-sectional view illustrating an image forming apparatus A according to an embodiment of the present invention including a sheet conveyance path. The perspective view showing the belt drive device B1 outline | summary which concerns on the example of embodiment. The figure which looked at the roller X with which the belt drive device B1 shown in FIG. The perspective view which looked at the roller X shown in FIG. 3 from diagonally side. The perspective view showing the outline | summary of belt drive device B2 which concerns on another example of embodiment. The figure which looked at roller Y with which belt drive B2 shown in Drawing 5 is provided from the side. The perspective view which looked at the roller Y shown in FIG. 6 from diagonally side. The perspective view showing the outline | summary of the belt drive device B3 which concerns on another example of embodiment. The figure which looked at the roller Z with which belt drive B3 shown in FIG. 8 is provided from the side. The perspective view which looked at the roller Z shown in FIG. 9 from diagonally side.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Finisher 2 ... Printer 3 ... Inserter 4, 8 ... Discharge tray 4a ... Movable discharge tray 5 ... Feed tray 6 ... Transfer device 7 ... Fixing device 8 ... Discharge tray 9, 12 ... Sheet conveyance path 10 ... Normal discharge Path 11: Post-processing discharge path R1, R2,... Sheet conveying roller J ... Belt W ... Driven rollers X, Y, Z ... Drive rollers X1, Y1, Z1 ... Belt running direction X2, X3, Y2, Z2, Z3 ... belt transport force Y3 ... flange members X4, X4-1, X4-2 ... spiral rib Y4 ... spiral ribs Z4, Z4-1, Z4-2, Z4-3, Z4-4 ... spiral Ribs X5, Y5, Z5 ... axial direction

Claims (7)

In a belt driving device that drives an endless belt stretched around a plurality of rollers,
A belt driving device characterized in that at least one of the rollers has a spiral groove or projection formed on the surface of the roller for carrying the belt in the direction of the center of the roller by a screw carrying action. In a belt driving device that drives an endless belt stretched around a plurality of rollers,
At least one of the rollers is provided on the roller by a spiral groove or protrusion that conveys the belt toward one end of the roller by a screw carrying action, and at the end of the roller. A belt drive device comprising: a flange member for preventing a deviation of the belt by contacting a side surface of the belt when the belt is carried. In a belt driving device that drives an endless belt stretched around a plurality of rollers,
At least one of the rollers has a spiral groove or protrusion formed on the surface near the center of the roller in a direction to carry the belt from the center of the roller to both ends of the roller by a screw carrying action. A belt driving device characterized in that a spiral groove or projection in the direction of carrying the belt toward the center of the roller is formed on the surface near the end of the roller by carrying the screw. 4. The belt according to claim 3, wherein the interval between the spiral grooves or protrusions formed on the surface near the center of the roller is wider than the interval between the spiral grooves or protrusions formed on the surface near the end of the roller. Drive device. The belt according to claim 4, wherein an interval between the spiral grooves or protrusions formed on the surface near the center of the roller is narrower than an interval between the spiral grooves or protrusions formed on the surface near the end of the roller. Drive device. An image forming apparatus comprising the belt driving device according to claim 1. The image forming apparatus according to claim 6, wherein the belt is a paper conveying belt or a transfer belt.

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