JP2010175689A - Endless belt unit and image forming apparatus equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an endless belt unit wherein an endless belt is positioned without causing meandering, and also, rib-wear is reduced, and to provide an image forming apparatus which is equipped with the endless belt unit. <P>SOLUTION: A positioning mechanism 69 includes an intermediate transfer belt driven roller 63 and the intermediate transfer belt 61. The intermediate transfer belt driven roller 63 includes a roller body 63A, a rotating shaft 63B, collars 63C and 63D. The intermediate transfer belt 61 includes ribs 61A and 61B at both ends thereof. The intermediate transfer belt 61 is stretched around the roller body 63A. The rotating shaft 63B freely rotatably supports the roller body 63A. The collars 63C and 63D are fitted idly to the rotating shaft 63B, while the roller body 63A is sandwiched therebetween. The ribs 61A and 61B are disposed at a distance L, to control the movement of the roller body 63A in the axial direction so that the intermediate transfer belt 61 does not meander. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an endless belt device having an endless belt stretched by a plurality of rollers.

  In general, in an image forming apparatus, a toner image is transferred onto a sheet by using an endless belt device including a transfer belt stretched by a plurality of rollers. The transfer belt is stretched by a plurality of rollers so as to be rotatable in the circumferential direction.

  In such an endless belt device, ribs are provided along both end portions in the width direction of the endless belt, and the ribs abut against the collar located inside in the axial direction to regulate the displacement of the transfer belt in the axial direction. What prevents the meandering of the transfer belt is disclosed.

JP 2006-337814 A

  However, in the conventional endless belt device, when the endless belt is rotationally driven at a relatively high speed, a pressing force that pushes the collar away from the roller body acts on the collar due to the bending of the rotation shaft of the roller body. The collar is fixed by being press-fitted into the rotating shaft of the roller. For this reason, the collar pushed out in the direction away from the roller main body is held at a position where it abuts against the rib without returning to the roller main body side, and there is a problem that the rib is worn.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an endless belt device capable of reducing wear of ribs while positioning an endless belt so as not to meander, and an image forming apparatus including the endless belt device.

  The endless belt device of the present invention is an endless belt device including an endless belt that is rotatably stretched by at least a first roller and a second roller, and includes a first roller and two ribs. The first roller includes a first roller body in which an endless belt is stretched over a part of a peripheral surface, a first rotating shaft provided so as to penetrate the first roller body in the axial direction, and a first roller body. The two collars are loosely fitted to the first rotating shaft so as to be sandwiched in the axial direction. The two ribs are formed at both ends of the endless belt that abuts the two collars. The distance between the two ribs is set longer than the sum of the two collars and the axial length of the first roller body by a distance at which the endless belt does not meander.

  In this configuration, the two collars are loosely fitted to the rotary shafts so as to be displaceable in the axial direction within a range where the endless belt does not meander. For this reason, the two collars are smoothly displaced toward the first roller body even if they are pushed out in a direction away from the first roller body.

  According to this invention, it is possible to position the endless belt so that the endless belt does not meander and reduce wear of the ribs.

1 is a diagram schematically illustrating an overall configuration of an image forming apparatus. FIG. 3 is a schematic diagram illustrating a configuration of an intermediate transfer belt unit. FIG. 3 is a schematic diagram illustrating a cross-sectional configuration of an intermediate transfer belt unit and an intermediate transfer belt.

  An image forming apparatus 10 according to a first embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram schematically illustrating the overall configuration of the image forming apparatus 10.

  The image forming apparatus 10 includes an image forming unit 11, an automatic document feeder 12, a reading unit 90, and a control unit 50. The image forming apparatus 10 is a multifunction machine that performs multicolor and single color image forming processing on paper according to image data.

  The automatic document feeder 12 sequentially conveys the document to the reading unit 90 disposed on the upper part of the image forming unit 11.

  The reading unit 90 has a document table 93 made of transparent glass at its end, and reads a document when sequentially conveyed documents pass through the document table 93. The reading unit 90 also reads a document placed on a document placing table 92 provided adjacent to the document table 93.

  The image forming unit 11 includes an exposure unit 14, an intermediate transfer belt unit (endless belt device) 60, a fixing unit 70, four image forming stations 20, a paper feed cassette 15, a manual feed tray 16, a paper discharge tray 17, and a secondary transfer unit. 30. The image forming unit 11 performs image forming processing on a sheet.

  The image forming station 20 is arranged according to each color image of black (K), cyan (C), magenta (M), and yellow (Y), and has the same configuration. Each image forming station 20 forms four types of electrostatic latent images corresponding to the respective colors. In the present embodiment, an example in which four image forming stations 20 are provided is described. However, a color latent image according to the specifications of the image forming apparatus 10 may be formed. In FIG. 1, only the image forming station 20 for forming a black (K) color image is shown.

  Here, only the image forming station 20 for forming a black (K) color image will be described.

  The image forming station 20 includes a developing unit (developing unit) 21, a photosensitive drum (image carrier) 22, a cleaner unit 23, and a charger 24, and forms a latent image corresponding to a black (K) color image. .

  The image forming station 20 includes a developing device 21, a photosensitive drum 22, a cleaner unit 23, and a charger 24, and forms a latent image corresponding to each color image.

  The developing device 21 supplies black (K) toner to the photosensitive drum 22, and the toner is attracted to the electrostatic latent image formed on the photosensitive drum 22 to visualize it.

  The cleaner unit 23 collects the toner remaining on the peripheral surface of the photosensitive drum 22 and discharges it through a conduit. The charger 24 is a charger-type charger that uniformly charges the surface of the photosensitive drum 22 to a predetermined potential.

  The exposure unit 14 is a laser scanning unit (LSU) provided with a laser emitting portion, a reflection mirror, and the like. The exposure unit 14 has a function of forming an electrostatic latent image corresponding to the image data on the surface thereof by exposing the charged photosensitive drum 22 according to the input image data.

  The intermediate transfer belt unit 60 is disposed above the photosensitive drum 22, and includes an intermediate transfer belt 61, an intermediate transfer belt driving roller (second roller) 62, an intermediate transfer belt driven roller (first roller) 63, and a plurality of intermediate transfer belts. A roller 64, an intermediate transfer belt cleaning unit 65, and a tension roller 66 are included.

  Four intermediate transfer belts 61 are arranged side by side corresponding to each color for YMCK, and rotate in the direction passing through the intermediate transfer belt driven roller 63, each image station 20, and the intermediate transfer belt drive roller 62 in this order. So that it is stretched. The intermediate transfer belt 61 is a belt made of a resin material having a low shrinkage rate. Specifically, the intermediate transfer belt 61 may be formed of a resin material such as polyamideimide, polyimide, or polycarbonate.

  The intermediate transfer belt 61 is inscribed in the intermediate transfer belt driving roller 62 and the intermediate transfer belt driven roller 63 so that the position in the direction orthogonal to the rotation direction of the intermediate transfer belt 61 falls within a predetermined range. Thereby, the positional deviation in the rotation direction of the intermediate transfer belt 61 is suppressed.

  The tension roller 66 is positioned between the intermediate transfer belt driving roller 62 and the intermediate transfer belt driven roller 63 and applies a predetermined tension to the intermediate transfer belt 61. The tension roller 66 is disposed so that the peripheral surface thereof abuts the central portion in the axial direction of the intermediate transfer belt 61.

  Four intermediate transfer rollers 64 are provided corresponding to each color for YMCK. Each intermediate transfer roller 64 is applied with a positive transfer bias of about several hundred volts. On the other hand, the toner image carried on the photosensitive drum 22 is charged with a negative polarity. As a result, the toner image is carried on the intermediate transfer belt 61. In the drawing, for the sake of simplicity, only the intermediate transfer roller 64 disposed corresponding to the image forming station 20 for forming a black (K) latent image is given a reference numeral.

  The intermediate transfer belt cleaning unit 65 includes a cleaning blade 65 </ b> A that wipes off residual toner, and collects residual toner adhering to each intermediate transfer belt 61. Thereby, the residual toner adhering to the intermediate transfer belt 61 can be collected.

  The cleaning blade 65 </ b> A is provided such that the tip of the cleaning blade 65 </ b> A contacts the intermediate transfer belt 61 at a position where the intermediate transfer belt 61 is sandwiched between the intermediate transfer belt driven roller 63. Therefore, the cleaning blade 65A can be brought into contact with the intermediate transfer belt driven roller 63 so as to be sandwiched between the cleaning blade 65A and the intermediate transfer belt driven roller 63. Therefore, the cleaning blade 65A can be brought into contact with the intermediate transfer belt 61 with a constant contact force.

  In the paper feed cassette 15, sheets used for image forming processing are stacked, and are provided below the exposure unit 14.

  A sheet used for image formation can also be placed on the manual feed tray 16. A paper discharge tray 17 provided above the image forming unit 11 is a tray for collecting sheets subjected to image forming processing in the image forming unit 11.

  The image forming unit 11 is provided with a paper conveyance path for sending the paper in the paper feed cassette 15 or the manual feed tray 16 to the paper discharge tray 17 via the secondary transfer unit 30 and the fixing unit 70.

  The registration roller pair 33 temporarily holds the paper conveyed along the paper conveyance path. Then, the sheet is conveyed between each upstream intermediate transfer belt 61 and the secondary transfer unit 30 at a timing when the toner image carried on each intermediate transfer belt 61 is aligned with the printing position of the sheet. Thereby, the toner image can be transferred to the paper.

  The secondary transfer unit 30 is press-contacted so that the secondary transfer belt 32 and the intermediate transfer belt 61 are sandwiched between a secondary transfer belt 32 stretched by a plurality of rollers and an intermediate transfer belt drive roller 62. A roller 31 is provided. The pressure roller 31 is a member made of a soft member such as foamed resin.

  The control unit 50 controls the document reading operation in the reading unit 90. The control unit 50 reads a document based on an input operation received via an operation panel (not shown). The control unit 50 causes the image forming unit 11 to execute image forming processing based on the read image data of the document.

  FIG. 2 is a schematic diagram showing the configuration of the intermediate transfer belt unit 60 in a top view. FIG. 3 is a schematic diagram showing a cross-sectional configuration of the intermediate transfer belt driven roller 63 and the intermediate transfer belt 61. In FIG. 2, the intermediate transfer belt 61 is indicated by a broken line. In FIG. 3, the lower intermediate transfer belt 61 is not shown.

  The intermediate transfer belt driven roller 63 and the intermediate transfer belt drive roller 62 are pivotally supported at both ends via bearings (not shown) provided on the frames FL1 to FL4.

  The intermediate transfer belt driven roller 63 has a roller body (first roller body) 63A, a rotation shaft (first rotation shaft) 63B, and collars 63C and 63D. An intermediate transfer belt 61 is stretched around the roller body 63A along the outer peripheral surface. The roller body 63A is a columnar member made of a hard material such as metal. The collars 63C and 63D are members made of polyacetal resin. In FIG. 2, the illustration of the collar 63C and the collar 63D is omitted.

  The intermediate transfer belt drive roller 62 has a roller body (second roller) 62A and a rotation shaft (second rotation shaft) 62B. The rotary shaft 62B is rotationally driven by a drive motor (not shown). An intermediate transfer belt 61 is wound around the roller body 62A along the outer peripheral surface. The roller body 62A is a columnar member made of a hard material such as metal. The rotation shaft 62B is shorter in the axial direction than the rotation shaft 63B. In addition, the interval between the frames FL3 and FL4 that respectively support both ends of the rotating shaft 62B is set to be shorter than the interval between the frames FL1 and 2 that respectively support both ends of the rotating shaft 63B. ing. For this reason, the rotating shaft 63B is more easily bent than the rotating shaft 62B.

  Here, the positioning mechanism 69 of the roller main body 63A of the intermediate transfer belt driven roller 63 will be described.

  The positioning mechanism 69 includes an intermediate transfer belt driven roller 63, collars 63C and 63D, and an intermediate transfer belt 61, and is a mechanism for positioning the intermediate transfer belt driven roller 63 so that the intermediate transfer belt 61 does not meander.

  The collars 63C and 63D are loosely fitted to the rotation shaft 63B so as to sandwich the roller body 63A in the axial direction. At both ends in the width direction of the intermediate transfer belt 61, ribs 61A and 61B are provided along the circumferential direction. The ribs 61A and the ribs 61B are provided at positions where the collars 63C and 63D come into contact with the collars 63C and 63D when the collars 63C and 63D are displaced in a direction away from the roller body 63A. The side surfaces on the inner peripheral side of the ribs 61A and the ribs 61B are provided at a distance L. On the other hand, the distance L1 between the side surfaces of the collar 63C and the collar 63D that respectively contact the rib 61A and the rib 61B is set to be shorter than the distance L. Here, the difference between the distance L and the distance L1 is set in advance so that the intermediate transfer belt 61 stretched over the roller body 63A does not meander even if the roller body 63A is displaced.

  Thus, by restricting the distance between the collars 63C and 63D so as not to exceed the distance L, the movement range of the roller body 63A is restricted to a range where the intermediate transfer belt 61 does not meander. The ribs 61A and 61B are members made of polyurethane.

  As described above, the collar 63C and the collar 63D are loosely inserted into the rotary shaft 63B so that the intermediate transfer belt 61 does not meander within the axial movement range of the rotary shaft 63B. For this reason, even when the collar 63C and the collar 63D are pushed out to a position where they contact the rib 61A and the rib 61B when the rotating shaft 63B is bent, the collar 63C and the collar 63D can be smoothly displaced toward the roller body 63A. it can.

  Therefore, it is possible to position the roller body 63A so that the intermediate transfer belt 61 does not meander while reducing the wear of the collars 63C and 63D and the ribs 61A and 61B. In addition, the collars 63C and 63D and the ribs 61A and 61B are shaved due to wear, and generation of powder is suppressed. Thereby, for example, it is possible to obtain an effect that the powder adheres to, for example, the toner image adsorbed on the intermediate transfer belt 61 and prevents the transfer of the toner image to the paper from being performed satisfactorily. .

  Further, by preventing meandering of the intermediate transfer belt 61, it is possible to obtain an effect that the contact force acting on the tip of the cleaning blade 65A from the intermediate transfer belt 61 is set to a preset value.

  In the present embodiment, an example is given in which the movement of the collars 63C and 63D in the axial direction is regulated by the ribs 61A and 61B, but the present invention is not limited to this. For example, instead of the ribs 61A and 61B, protrusions protruding in the radial direction may be provided on the rotary shaft 63B, respectively, to restrict the movement ranges of the collars 63C and 63D.

  When the speed at which the intermediate transfer belt driving roller 62 rotates the intermediate transfer belt 61 is relatively high, the collars 63C and 63D are made to be ribs 61A and 61B by bending of the rotation shaft 63B of the intermediate transfer belt driven roller 63, respectively. A relatively large pressing force pressing toward the side tends to act periodically or temporarily.

  Further, for example, when the collars 63C and 63D are press-fitted into the rotating shaft 63B, the collars 63C and 63D are pressed radially outward from the rotating shaft 63B. For this reason, when the collars 63C and 63D are pushed out toward the ribs 61A and 61B, the collars 63C and 63D are held at positions where they abut against the ribs 61A and 61B, respectively.

  For this reason, the contact force between the rib 61A and the collar 63C is maintained in a large state, and is easily worn. Similarly, a large contact force acts between the rib 61B and the collar 63D, and wear easily occurs.

  Therefore, by providing the positioning mechanism 69 on the intermediate transfer belt driven roller 63, it is possible to obtain the effect of reducing the deflection of the rotating shaft 63B and smoothly returning the collars 63C and 63D to the roller body 63A side.

  In the embodiment described above, an example in which the interval between the frames FL1 and FL2 is wider than the interval between the frames FL3 and FL4 is described. However, the present invention is not limited to this. For example, the interval between the frames FL1 and FL2 may be provided so as to be equal to the interval between the frames FL3 and FL4. More specifically, there may be a case where the frame FL1 and the frame 3 are integrally formed and the frame FL2 and the frame FL4 are integrally formed.

  In the above embodiment, the interval between the frames FL1 and FL2 is wider than the interval between the frames FL3 and FL4, and the diameters of the rotation shaft 62B and the rotation shaft 63B are the same. An example is given for explanation. However, the present invention is not limited to this. For example, even when the rigidity of the rotating shaft 63B is smaller than the rigidity of the rotating shaft 62B and easily bends, the same effect as the above embodiment can be obtained by providing the positioning mechanism 69. In addition, as a case where the rigidity of the rotating shaft 63B is smaller than the rigidity of the rotating shaft 62B, a case where the diameter of the rotating shaft 63B is provided smaller than the diameter of the rotating shaft 62B can be considered. It is also conceivable that the Young's modulus of the rotating shaft 63B is smaller than the Young's modulus of the rotating shaft 62B. In these cases, the same effect as that of the above embodiment can be obtained by providing the positioning mechanism 69.

  In the above-described embodiment, as an example in which the rotating shaft 63B is easily bent, the case where the axial length of the rotating shaft 63B is longer than the axial length of the rotating shaft 62B is described as an example. However, the present invention is not limited to this. For example, if the rotating shaft 63B is pivotally supported by the frames FL1 and FL2 so as to be easily bent, the same effect as that of the above embodiment can be obtained by providing the positioning mechanism 69.

  In the above embodiment, the intermediate transfer belt driven roller 63 has been described as an example having the endless belt positioning mechanism 69. However, the present invention is not limited to this. For example, the intermediate transfer belt drive roller 62 may have an endless belt positioning mechanism 69.

  In the above embodiment, the intermediate transfer belt driven roller 63 is provided with the positioning mechanism 69, but the present invention is not limited to this. For example, one of a plurality of rollers on which a transfer belt for transferring a toner image adhering to the peripheral surface of the photosensitive drum to the paper is sandwiched between the photosensitive drum and the photosensitive drum is provided with a positioning mechanism 69 It is also good.

  In the above embodiment, the positioning mechanism 69 included in the intermediate transfer belt driven roller 63 is taken as an example, but the present invention is not limited to this. If the endless belt positioning mechanism according to the present invention is provided in the roller for stretching the endless belt, the same effect as the positioning mechanism 69 according to the above embodiment can be obtained.

  In the above embodiment, an example is given in which the rotation shaft 62B is provided with a shorter axial length than the rotation shaft 63B. However, the present invention is not limited to this. For example, when the rotation shaft 63B is largely bent, both the rotation shafts 63B and 62B have the same axial length, and the rotation shaft 62B has a longer axial length than the rotation shaft 63B. By providing the positioning mechanism 69, the same effect as that of the positioning mechanism 69 according to the above embodiment can be obtained.

  In the above embodiment, the case where the pressure roller 31 is made of a soft material and the roller body 62A is made of a hard material is described as an example. However, the present invention is not limited to this. For example, the pressure roller 31 may be formed of a hard material, and the roller body 62A may be formed of a soft material.

  The above description of the embodiment is to be considered in all respects as illustrative and not restrictive. The scope of the present invention is shown not by the above embodiments but by the claims. Furthermore, the scope of the present invention is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

61 Intermediate transfer belt (endless belt)
61A, 61B Rib 63 Intermediate transfer belt driven roller (first roller)
63A Roller body (first roller body)
63B Rotating shaft (first rotating shaft)
63D, 63D color 69 positioning mechanism

Claims (4)

An endless belt device comprising an endless belt rotatably stretched by at least a first roller and a second roller,
A first roller body having the endless belt spanned on a part of a peripheral surface; a first rotating shaft provided so as to penetrate the first roller body in the axial direction; and the first roller body in the axial direction. The first roller constituted by two collars loosely fitted to the first rotating shaft so as to be sandwiched;
Two ribs respectively formed at both ends of the endless belt contacting the two collars;
With
The distance between the two ribs is longer than the sum of the lengths in the axial direction of the two collars and the first roller body by a distance at which the endless belt does not meander.
Endless belt device. The second roller constituted by a second roller body in which the endless belt is stretched over a part of a peripheral surface, and a second rotating shaft that rotationally drives the second roller body;
The axial length of the second rotary shaft is shorter than the axial length of the first rotary shaft.
Endless belt device. An image carrier having an electrostatic latent image formed on the surface and rotating in a predetermined rotation direction;
A developing unit that supplies toner to the image carrier and visualizes the electrostatic latent image as a toner image;
The endless belt device according to claim 1 or 2, wherein the endless belt includes a transfer belt unit configured to transfer a toner image formed on a surface of the image carrier onto a sheet,
An image forming apparatus. An image carrier having an electrostatic latent image formed on the surface and rotating in a predetermined rotation direction;
A developing unit that supplies toner to the image carrier and visualizes the electrostatic latent image as a toner image;
The endless belt device according to claim 1, wherein the endless belt includes an intermediate transfer belt unit configured by an intermediate transfer belt for attracting and conveying a toner image formed on the surface of the image carrier. ,
A secondary transfer belt unit for transferring a toner image conveyed by the intermediate transfer belt onto a sheet sandwiched between the intermediate transfer belt;
An image forming apparatus.

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