JP2009294575A - Belt unit and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a belt unit which achieves stable rotation of a belt by preventing meander prevention ribs from riding on the ends of a roller, and to provide an image forming apparatus having the belt unit. <P>SOLUTION: The belt unit includes: an intermediate transfer belt 21 extended tight by a plurality of rollers and rotated endlessly; and the pair of meander prevention ribs 21a disposed along both widthwise edges of the intermediate transfer belt 21 so that their inside parts 21a1 are able to abut on both lengthwise ends of the roller. This belt unit includes a pair of slack prevention pulleys 24B freely rotatably disposed on rotation shafts 24 provided at both ends of the tension roller 24 and supporting the bottoms 21a2 of the meander prevention ribs 21a. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a belt unit including a meandering prevention rib and an image forming apparatus such as a copying machine, a printer, or a facsimile machine including the belt unit.

In a belt unit including a belt that is installed on a plurality of rollers and that runs endlessly, in order to prevent meandering in the width direction (the axial direction of the roller) with respect to the belt running direction, There are known ones provided with ribs for preventing meandering.
In Patent Document 1 as a belt unit having such a meandering prevention rib, a stepped portion (groove) is provided at both ends of the roller, and the inner side of the meandering prevention rib is brought into contact with both ends, The meandering in the width direction is regulated.
JP 2005-215440 A

However, in the belt unit, there may be a problem that the meandering prevention rib runs on the end of the roller.
One of the causes is the drooping of the end of the belt in the width direction. The belt is provided with meandering prevention ribs at both edges in the width direction of the belt, but the bottom cannot be supported by a roller. For example, when the bottom portion of the meandering prevention rib is brought into contact with and supported by the stepped portion, the speed of the roller peripheral surface for rotating the belt is different from the speed of the stepped portion peripheral surface having a small diameter with respect to the peripheral surface. For this reason, friction is generated at the contact portion, and there is a possibility that a shearing force is applied to the belt to cause deformation or destruction, or the belt meandering may be promoted.
As a result, the tension in the end in the belt width direction where the meandering prevention rib whose bottom is not supported is provided occurs, and the end in the belt width direction droops.

  The present invention has been made in view of the above problems, and a belt unit capable of preventing the meandering rib from climbing on the roller end portion and achieving stable belt running, and the belt unit. An object of the present invention is to provide an image forming apparatus.

In order to solve the above-described problems, the present invention provides a belt which is installed on a plurality of rollers and runs endlessly, and is provided along edges on both sides in the width direction of the belt. A belt unit having a pair of meandering prevention ribs against which the inner side portions can abut, each of which is rotatably provided on the rotation shafts at both ends of the roller, and has a bottom part of the meandering prevention rib. A configuration is adopted in which a pair of pulleys for supporting each is provided.
By adopting such a configuration, in the present invention, the bottom portion of the meandering prevention rib is supported by a pulley that is rotatable with respect to the rotation shaft of the roller.

Further, in the present invention, a configuration is adopted in which the pulley is provided on a driven roller that is driven to rotate by the rotational driving of a driving roller that rotates the belt.
By adopting such a configuration, in the present invention, the drive roller for gripping and driving the belt has a high grip force and it is difficult to correct the meandering of the belt, whereas the grip force of the belt is applied to the drive roller. On the other hand, it is possible to easily correct the meandering of the belt by providing a pulley in a low driven roller.

Further, in the present invention, a plurality of the driven rollers are provided, and the pulley is provided on a tension roller that is provided with a biasing device and applies tension to the belt among the driven rollers. adopt.
By adopting such a configuration, in the present invention, the pulley is provided on a tension roller provided with a predetermined range of motion by an urging device for applying tension to the belt. Therefore, when a load is applied to the tension roller in the axial direction for correcting the meandering, the belt can be flexibly moved while the load is absorbed by the movable range to correct the meandering of the belt.

In the present invention, an image forming apparatus provided with the belt unit configured as described above is employed.
By adopting such a configuration, in the present invention, an image forming apparatus provided with the belt unit is obtained.

According to the present invention, a belt that is installed on a plurality of rollers and runs endlessly, and is provided along edges on both sides in the width direction of the belt, and each inner portion abuts on both ends in the length direction of the roller. A belt unit including a pair of possible meandering prevention ribs, each of which is rotatably provided on the rotation shafts at both ends of the roller, and a pair of pulleys that respectively support the bottoms of the meandering prevention ribs. By adopting the configuration, the bottom of the meandering prevention rib is supported by a pulley that is rotatable with respect to the rotation shaft of the roller. Thus, it is possible to prevent friction at the bottom of the meandering prevention rib and to prevent the end of the belt width direction from sagging.
Therefore, according to the present invention, there is an effect that it is possible to provide a belt unit that can prevent the meandering prevention rib from running on the roller end portion and achieve stable belt running.

  Next, embodiments of the present invention will be described with reference to the drawings. In the following description, an example in which the present invention is applied to a printer (image forming apparatus) will be described. In the following drawings, the scale of each member is appropriately changed in order to make each member a recognizable size.

First, the configuration of the printer P in the present embodiment will be described with reference to FIG.
FIG. 1 is a schematic diagram illustrating a configuration of a printer P according to an embodiment of the present invention.
As shown in FIG. 1, the printer P transfers an image formed on the image forming unit 2 that forms an image on the storage medium, a paper feed cassette 3 that stores the storage medium, and the image formed on the image forming unit 2 to the storage medium. A secondary transfer unit 4 for fixing, a fixing unit 5 for fixing the transferred image on the storage medium, a discharge tray 6 for receiving the storage medium that has been fixed and discharged, and a discharge tray 6 from the sheet feeding cassette 3. And a transport path 7 for transporting the storage medium.

The image forming unit 2 includes a belt unit 20, a cleaning unit 30, and image forming units F (FY, FM, and F) corresponding to the respective colors of yellow (Y), magenta (M), cyan (C), and black (BK). FC, FB).
The belt unit 20 includes an intermediate transfer belt (belt) 21 to which an image is transferred from the image forming unit F, a driving roller (roller) 22 that lays the intermediate transfer belt 21 and rotates endlessly, a driven roller (roller) 23, Tension roller (roller) 24.

The intermediate transfer belt 21 is stretched around a driving roller 22, a driven roller 23, and a tension roller 24, and is configured to run endlessly clockwise in FIG.
The drive roller 22 is connected to a drive unit having a drive source such as a motor, and rotates while applying a grip force to the intermediate transfer belt 21.
The driven roller 23 is driven to rotate following the rotational drive of the drive roller 22.
The tension roller 24 is a type of driven roller that is driven to rotate by the rotational driving of the driving roller 22, and is provided with a biasing device 25 having a spring mechanism to apply tension to the intermediate transfer belt 21. Such a tension roller 24 is provided between the driving roller 22 and the driven roller 23, on the downstream side of the driving roller 22 and in the vicinity of the upstream side of the driven roller 23.

  The cleaning unit 30 includes a cleaning roller, a cleaning blade, and the like, and is configured to remove toner remaining on the intermediate transfer belt 21.

The image forming unit F includes a photoconductor 10, a charger 11, an exposure device 12, a developing device 13, and a primary transfer roller 14, and further includes a cleaning device and a charge removal device (not shown).
The photoconductor 10 is formed in a cylindrical shape, and an electrostatic latent image and a toner image based on the electrostatic latent image are formed on the peripheral surface thereof. The charger 11 is disposed so as to face the photoconductor 10 and charges the peripheral surface of the photoconductor 10. The exposure device 12 scans the peripheral surface of the charged photoconductor 10 with laser light emitted based on image data in the print format. The developing device 13 develops an image based on the electrostatic latent image on the peripheral surface of the photoconductor 10 by supplying toner to the peripheral surface of the photoconductor 10. The primary transfer roller 14 is disposed opposite to the photoconductor 10 with the intermediate transfer belt 21 interposed therebetween, and primarily transfers an image developed on the photoconductor 10 to the intermediate transfer belt 21.

The paper feed cassette 3 can be pulled out with respect to the apparatus main body and accommodates a storage medium.
The secondary transfer unit 4 performs secondary transfer of an image formed on the intermediate transfer belt 21 to a storage medium. The secondary transfer unit 4 sandwiches the drive roller 22 that drives the intermediate transfer belt 21 and the intermediate transfer belt 21 therebetween. A secondary transfer roller 41 disposed opposite to the driving roller 22 is provided.
The fixing unit 5 fixes the image secondarily transferred onto the storage medium, and includes a heating roller 51 that fixes the toner by pressing and heating.
The transport path 7 includes a pickup roller 71 that transports the storage medium from the paper feed cassette 3, a paper feed roller 72 that transports the storage medium, and a paper discharge roller 73 that discharges the storage medium to the paper discharge tray 6.

Next, the configuration of the belt unit 20 will be described in detail with reference to FIGS. 2 and 3.
FIG. 2 is an enlarged perspective view of a main part in the vicinity of the tension roller 24 in the embodiment of the present invention.
FIG. 3 is a sectional view in the axial direction of the tension roller 24 in the embodiment of the present invention.

  As shown in FIGS. 2 and 3, the intermediate transfer belt 21 is provided with a pair of meandering prevention ribs 21 a along edges on both sides in the width direction. As shown in FIG. 3, the meandering prevention rib 21 a has a substantially rectangular shape in cross-sectional view, and is configured to protrude vertically from the running surface on the back side of the intermediate transfer belt 21. Such a meander-preventing rib 21a is formed of, for example, a resin material having elasticity, and its inner portion 21a1 can be brought into contact with both end portions in the length direction of each roller so that the meandering of the intermediate transfer belt 21 is performed. It is the composition which corrects.

As shown in FIG. 2, the driven roller 23 is provided with a pair of meandering restriction pulleys 23 </ b> B so as to be rotatable on the rotation shafts 23 </ b> A at both ends.
The meandering restriction pulley 23B has a large-diameter portion having substantially the same diameter as the peripheral surface of the driven roller 23, and a smaller diameter than the large-diameter portion (for example, a diameter capable of contacting the bottom portion 21a2 of the meander-preventing rib 21a). A stepped portion having a small diameter portion is provided, and the meandering of the intermediate transfer belt 21 is corrected and regulated by bringing the inner portion 21a1 of the meandering prevention rib 21a into contact with the stepped portion.

As shown in FIGS. 2 and 3, the tension roller 24 is provided with urging devices 25 at both ends in the length direction, and has a predetermined movable range for applying a desired tension to the intermediate transfer belt 21. The tension roller 24 is provided with a pair of anti-dripping pulleys (pulleys) 24 </ b> B that are respectively rotatable on the rotation shafts 24 </ b> A at both ends thereof.
The sag prevention pulley 24B is formed in a cylindrical shape, is loosely fitted to the rotating shaft 24A with a slight clearance, and the width of the peripheral surface is designed to be larger than the width of the meandering prevention rib 21a ( (See FIG. 3). Further, the outer diameter of the sag prevention pulley 24B has a diameter that can contact the bottom 21a2 of the meandering prevention rib 21a.
The sag prevention pulley 24B is preferably formed of an oil-containing resin material that reduces friction with the rotation shaft 24A.

Next, the operation of the belt unit 20 configured as described above will be described.
As shown in FIG. 1, the intermediate transfer belt 21 is gripped by the driving roller 22 and is driven to endlessly rotate clockwise. At this time, a tensile force is applied to the intermediate transfer belt 21 in the vicinity of the upstream of the drive roller 22, and an extrusion force is applied to the intermediate transfer belt 21 in the vicinity of the downstream of the drive roller 22 that has passed through the drive roller 22. Become. That is, the intermediate transfer belt 21 is difficult to meander on the upstream side of the drive roller 22 because it is gripped and a pulling force is applied. However, on the downstream side after the drive roller 22, an extrusion force is applied and the intermediate transfer belt 21 is bent. Tend to meander.

The tension roller 24 provided on the downstream side of the driving roller 22 applies tension to the intermediate transfer belt 21 and corrects / regulates meandering of the intermediate transfer belt 21, and the intermediate transfer belt is supported by a sag prevention pulley 24B. 21 is prevented from sagging at the end in the width direction.
More specifically, as shown in FIG. 3, the sag prevention pulley 24B abuts against the bottom 21a2 of the meandering prevention rib 21a and supports the entire width direction of the intermediate transfer belt 21 in the width direction. Prevent sagging of parts.

  Furthermore, since the sag prevention pulley 24B is loosely fitted to the rotation shaft 24A and is freely rotatable, it is possible to reduce friction due to contact with the meandering prevention rib 21a. That is, the intermediate transfer belt 21 is subjected to shearing force through the meandering prevention rib 21a due to friction generated by supporting the meandering prevention rib 21a, which may cause deformation or destruction, or the intermediate transfer belt 21 may be meandered. The fear of doing so can be eliminated.

  Further, since the tension roller 24 has a predetermined movable range by the urging device 25, even when the tension roller 24 receives a load in the axial direction from the meandering prevention rib 21 a due to the meandering of the intermediate transfer belt 21, The meandering of the intermediate transfer belt 21 can be corrected by moving flexibly while absorbing the load by the elastic force of the spring.

As described above, in the tension roller 24, the intermediate transfer belt 21, which has been prevented from dripping at the end in the width direction due to the tension, reaches the driven roller 23 immediately downstream.
In the driven roller 23, the meandering pulley 21B shown in FIG. 2 is brought into contact with the inner portion 21a1 of the meandering prevention rib 21a to correct and regulate the meandering of the intermediate transfer belt 21.
At this time, since the sag of the end portion in the width direction of the intermediate transfer belt 21 is restricted in the tension roller 24, the meandering prevention rib 21a can stably enter the meandering restriction pulley 23B. That is, it is possible to solve the problem that the meandering prevention rib 21a in a suspended state enters, rides on the meandering restriction pulley 23B, and further rides on the peripheral surface at the end of the driven roller 23.

Therefore, according to the above-described embodiment, the intermediate transfer belt 21 that is installed on a plurality of rollers and runs endlessly, and the edges of both sides of the intermediate transfer belt 21 in the width direction are provided. The belt unit 20 includes a pair of meandering-preventing ribs 21a with which both inner side portions 21a1 can come into contact with both ends, which are rotatably provided on the rotation shafts 24A at both ends of the tension roller 24, and meandering. By adopting a configuration having a pair of sag prevention pulleys 24B that respectively support the bottom portions 21a2 of the prevention ribs 21a, the meander prevention ribs 21a are supported by the sag prevention pulleys 24B that are rotatable with respect to the rotation shaft 24A of the tension roller 24. The bottom 21a2 is supported. From this, it is possible to prevent friction on the bottom 21a2 of the meandering prevention rib 21a and to prevent the end of the intermediate transfer belt 21 in the width direction from sagging.
Therefore, in the present embodiment, there is an effect that it is possible to provide the belt unit 20 that can prevent the meandering prevention rib 21a from running on the roller end portion and can achieve the stable rotation of the intermediate transfer belt 21. .

  In this embodiment, the sag prevention pulley 24 </ b> B is provided on the tension roller 24 of a driven roller that is driven to rotate by the rotational drive of the drive roller 22 that rotates the intermediate transfer belt 21. As a result, the drive roller 22 that grips and drives the intermediate transfer belt 21 has a high grip force and it is difficult to correct the meandering of the intermediate transfer belt 21, whereas the grip force of the intermediate transfer belt 21 causes the drive roller 22 to grip. On the other hand, the meandering of the intermediate transfer belt 21 can be easily corrected by providing the anti-dripping pulley 24B in the low tension roller 24.

  In the present embodiment, a plurality of the driven rollers are provided, and the sag prevention pulley 24B is provided on the tension roller 24 that is provided with a biasing device 25 of the driven rollers and applies tension to the intermediate transfer belt 21. By adopting such a configuration, when a load is applied to the tension roller 24 in the axial direction for correcting meandering, the tension roller 25 can move flexibly while absorbing the load by the range of motion by the urging device 25. Thus, the meandering of the intermediate transfer belt 21 can be corrected.

  Further, in the present embodiment, the printer P provided with the belt unit 20 capable of achieving stable rotation of the intermediate transfer belt 21 is obtained. That is, since the intermediate transfer belt 21 is prevented from climbing onto the roller end, there is an effect that the image can be transferred stably by the image forming unit 2. Further, since the meandering of the intermediate transfer belt 21 is effectively corrected and regulated, there is an effect of improving the image transfer accuracy by the image forming unit 2.

  As mentioned above, although preferred embodiment of this invention was described referring drawings, this invention is not limited to the said embodiment. Various shapes, combinations, and the like of the constituent members shown in the above-described embodiments are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

For example, the sag prevention pulley 24B in the present embodiment has been described as having a diameter capable of supporting the bottom 21a2 of the meandering prevention rib 21a over the entire width direction, but the present invention is limited to the above configuration. It is not something.
The sag prevention pulley 24B may be configured to support a part of the bottom 21a2 of the meandering prevention rib 21a, for example.
Further, the sag prevention pulley 24B is not limited to a configuration having a diameter that completely prevents the end of the intermediate transfer belt 21 in the width direction, and for example, even if there is a certain amount of sag, a rib for preventing meandering What is necessary is just a structure which has a diameter which can be supported so as to prevent the roller 21 (the driven roller 23 in the above-described embodiment) from riding on the end of the roller 21a.

1 is a schematic diagram illustrating a configuration of a printer according to an embodiment of the present invention. It is a principal part expansion perspective view of the tension roller vicinity in embodiment of this invention. It is sectional drawing in the axial direction of the tension roller in embodiment of this invention.

Explanation of symbols

  P: printer (image forming apparatus), 20: belt unit, 21: intermediate transfer belt (belt), 21a: meandering prevention rib, 21a1: inner side, 21a2: bottom, 22: driving roller, 23: driven roller, 24 ... Tension roller, 24A ... Rotating shaft, 24B ... Drip prevention pulley (pulley), 25 ... Biasing device

Claims (4)

A belt that is installed on a plurality of rollers and that runs endlessly, and a pair of meanders that are provided along edges of both sides of the belt in the width direction so that the inner portions of the belt can come into contact with both ends in the length direction A belt unit comprising a rib for use,
A belt unit comprising a pair of pulleys rotatably provided on the rotation shafts at both ends of the roller and supporting the bottom portions of the meandering prevention ribs.   The belt unit according to claim 1, wherein the pulley is provided on a driven roller that is driven to rotate by a rotational drive of a drive roller that rotates the belt. A plurality of the driven rollers are provided,
The belt unit according to claim 2, wherein the pulley is provided on a tension roller that is provided with an urging device among the driven rollers and applies tension to the belt.   An image forming apparatus comprising the belt unit according to claim 1.

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