JP2013246220A - Belt controller, roller unit, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem in which: when a belt is deviated in an axial direction of rollers to abut against a flange, an end of the belt is applied with a large load; after the abutment of the belt against the flange, when the belt runs while the end of the belt abuts against the flange, the end continues to be applied with the load; and the load thus applied causes cracks in the end of the belt, which results in damage to the belt.SOLUTION: A belt 3 is laid over a plurality of rollers, and runs in association with the rotation of the rollers. A belt controller controls the movement of the belt 3 in the axial direction of the rollers. At least one roller 52 of the plurality of rollers has, on at least one end thereof, a belt abutting part 7 against which an end of the belt abuts; and the belt abutting part is flexible.

Description

  The present invention relates to a belt control device that controls movement of a belt that is stretched around a plurality of rollers and travels with the rotation of the plurality of rollers in the axial direction of the rollers.

  In conventional image forming apparatuses, various belts are used as an intermediate transfer member, a recording medium conveyance unit, an image fixing unit, or the like. These belts are configured to run along with the rotation of the rollers in a state of being stretched over at least two rollers provided in parallel to each other. However, the rollers may not be parallel to each other due to the state of the parts used to rotate the rollers. When the plurality of rollers are not parallel to each other, a so-called belt shift occurs in which the belt approaches the roller axial direction (hereinafter referred to as the roller axial direction). Due to this belt shift, there has been a problem that the belt is detached from the roller and damaged.

  In order to prevent such belt shift, a technique is known in which a flange is provided at the end of the roller to stop the belt from moving in the roller axial direction. For example, in Patent Document 1, an annular flange is disposed at the end of the roller, and a guide roller that is in contact with the surface of the belt is disposed on the inner side of the flange, thereby restricting the belt from moving in the roller axial direction. Is described.

  However, in the technique described in Patent Document 1, when the belt close to the axial direction of the roller hits the flange, the end portion of the belt receives a large load. Furthermore, after the belt hits the flange, the belt continues to receive a load from the flange when traveling while contacting the flange at its end. Due to the load received in this manner, there is a problem that the end of the belt is cracked and the belt is damaged.

  A belt control device that controls movement of a belt that is stretched around a plurality of rollers and travels along with the rotation of the rollers in the axial direction of the rollers, and at least one of at least one of the plurality of rollers. It has a belt contact part which the edge part of the said belt contact | connects to an edge part, The said belt contact part is flexible, It is characterized by the above-mentioned.

  According to the present invention, at least one end of at least one of the plurality of rollers has a belt contact portion that contacts the end of the belt, and the belt contact portion is flexible. It is possible to reduce the load applied to the end portion, thereby preventing the belt from being damaged.

1 is a schematic configuration diagram of an example of an image forming apparatus according to an embodiment. It is a figure showing the belt control apparatus which concerns on this embodiment. It is a figure showing the belt control apparatus which concerns on this embodiment. It is a figure showing the belt contact part of the belt control apparatus which concerns on this embodiment. It is a figure showing the conventional belt control apparatus. It is a figure showing the conventional belt control apparatus.

  An embodiment of the present invention will be described.

  FIG. 1 is a schematic configuration diagram showing an example of an image forming apparatus configured as a printer. The image forming apparatus shown here includes first to fourth photosensitive members 1a, 1b, 1c and 1d are provided. A toner image of a different color is formed on each photoconductor, and a black toner image, a magenta toner image, a cyan toner image, and a yellow toner image are formed on these photoconductors 1a, 1b, 1c, and 1d, respectively. The

  An intermediate transfer belt 3 configured as an intermediate transfer member is provided opposite to the first to fourth photosensitive members 1a, 1b, 1c, and 1d, and the respective photosensitive members 1a, 1b, 1c, and 1d are provided on the intermediate transfer belt 3. It touches the surface. The intermediate transfer belt 3 is stretched around a drive roller 51 and support rollers 52, 53, and 54. The driving roller 51 is rotated by a driving source (not shown), and the intermediate transfer belt 3 is moved in the direction indicated by the arrow A by the rotation of the driving roller 51. The intermediate transfer belt 3 may have a multilayer structure or a single layer structure. However, if the intermediate transfer belt 3 is a multilayer structure, the base layer is made of, for example, a fluororesin, PVDF sheet, or polyimide resin with little elongation, and the surface is smooth such as a fluororesin. What is covered with a good coat layer is preferable. Moreover, if it is a single layer, what uses materials, such as PVDF, PC, a polyimide, is good. Note that any of the drive roller 51 and the support rollers 52, 53, and 54 is referred to as a roller.

  The configuration for forming a toner image on the photoreceptors 1a, 1b, 1c, and 1d is substantially the same as the configuration for transferring each toner image onto the intermediate transfer belt 3, and the color of each formed toner image Are only different. Therefore, only a configuration in which a black toner image is formed on the first photoconductor 1a and the toner image is transferred onto the intermediate transfer belt 3 will be described, and the second to fourth photoconductors 1b, 1c, and 1d will be described. The description of the configuration is omitted. The photoreceptor 1a is rotationally driven in the direction indicated by the arrow B in FIG. At this time, the surface of the photoconductor 1 is irradiated with light from a static eliminator (not shown), and the surface potential of the photoconductor 1a is initialized. A charging device 8a is installed in the vicinity of the photosensitive member 1a, and the surface of the photosensitive member whose surface potential is initialized is uniformly charged to a negative polarity by the charging device 8a. The surface of the photosensitive member thus charged is irradiated with the light-modulated laser beam L emitted from the exposure device 9, and an electrostatic latent image corresponding to the writing information is formed on the surface of the photosensitive member 1a. In the image forming apparatus of the present embodiment, an exposure device 9 having a laser writing device that emits a laser beam L is used.

  A developing device 10a is installed in the vicinity of the photoreceptor 1a. The electrostatic latent image formed on the photoreceptor 1a is visualized as a black toner image when passing through the developing device 10a. On the other hand, a transfer roller 11a is provided so as to face the photoreceptor 1a and sandwich the intermediate transfer belt 3.

  The transfer roller 11a is applied with a positive transfer voltage having a polarity opposite to the toner charge polarity of the toner image formed on the photoreceptor 1a. As a result, a transfer electric field is formed between the photosensitive member 1a and the intermediate transfer belt 3, and the toner image on the photosensitive member 1a is electrostatically applied to the intermediate transfer belt 3 that is driven to rotate in synchronization with the photosensitive member 1a. Transcribed. The transfer residual toner adhering to the surface of the photoreceptor 1a after the toner image is transferred to the intermediate transfer belt 3 is removed by the cleaning device 12a, and the surface of the photoreceptor 1a is cleaned.

  Similarly, a magenta toner image, a cyan toner image, and a yellow toner image are formed on the second to fourth photoconductors 1b, 1c, and 1d, respectively. Then, the toner images of the respective colors are electrostatically transferred in an overlapping manner on the intermediate transfer belt 3 onto which the black toner image has been transferred to form a composite toner image.

  As shown in FIG. 1, a paper feeding device 14 is provided in the lower part of the image forming apparatus, and the recording medium P is sent out in the direction of arrow C by the rotation of the paper feeding roller 15. The sent recording medium P is fed by the registration roller pair 16 between the driving roller 51 and the secondary transfer roller 17 installed to face the driving roller 51. At this time, a predetermined transfer voltage is applied to the secondary transfer roller 17, whereby the composite toner image on the intermediate transfer belt 3 is secondarily transferred to the recording medium P.

  The recording medium P on which the composite toner image is secondarily transferred is further conveyed upward and passes through the fixing device 18. At this time, the fixing device 18 fixes the toner image on the recording medium P by the action of heat and pressure. The recording medium P that has passed through the fixing device 18 is discharged out of the image forming apparatus via a pair of paper discharge rollers 19 provided in the paper discharge unit.

  Further, the transfer residual toner adhering to the intermediate transfer belt 3 after the toner image transfer is removed by the belt cleaning device 20. The belt cleaning device 20 in the present embodiment has a blade-shaped cleaning blade 21 made of urethane or the like, and this cleaning blade 21 is provided so as to scrape off transfer residual toner attached to the intermediate transfer belt 3. ing. Various types of belt cleaning devices 20 can be used as appropriate. For example, the belt cleaning device 20 may be of an electrostatic cleaning type using a conductive fur brush.

  Next, the belt control device used in this embodiment will be described. In the following description, the intermediate transfer belt 3 is referred to as a belt 3. The belt control device of this embodiment is provided on one side of the support roller 52 of the image forming apparatus in FIG. Therefore, in FIG. 2 and subsequent figures, one side of the support roller 52 is shown in an enlarged view. FIG. 2 is a schematic cross-sectional view of the belt control device of the first embodiment.

  As shown in FIG. 2, the belt control device has a roller shaft 6 that is coaxial with the shaft of the support roller 52 at the end of the support roller 52. The roller shaft 6 has a cylindrical shape whose diameter is shorter than that of the support roller 52, and passes through the support roller 52, a belt contact portion 7 described later, and a belt contact portion holding portion 70.

  The belt contact portion 7 is provided outside the direction of the axis of the support roller 52 (the z direction shown in FIG. 2, hereinafter referred to as the roller axis direction) (the direction from the central portion toward the end of the support roller 52). ing. The belt contact portion 7 comes into contact with the belt end 3a when the belt 3 moves in the roller axial direction, and can be bent by a force received from the belt end 3a (hereinafter, possible). Realized by polyethylene terephthalate). The belt contact portion 7 may be made of any material as long as it is made of a flexible material such as polyethylene naphthalate in addition to polyethylene terephthalate.

  The belt contact portion 7 has a sheet-like shape with a thickness of about 0.1 mm to 1.0 mm, and the plane of the sheet (referred to as the sheet plane portion 7a) is substantially perpendicular to the roller axial direction. It is provided as follows. Further, the peripheral edge of the sheet flat surface portion 7 a forms a circle, and the center of the circle is on the axis of the support roller 52. The belt contact portion holding portion 70 holds the central portion of the belt contact portion 7 so that the belt contact portion 7 is provided in this way.

  With such a configuration, when the belt 3 moves outward in the roller axis direction, the belt 3 contacts the sheet flat surface portion 7a of the belt contact portion 7. At this time, since the belt contact portion 7 is flexible, the load applied when the belt end portion 3 a contacts the belt contact portion 7 is reduced as compared with the case where the belt contact portion 7 is not provided.

  The sheet flat surface portion 7a only needs to be in contact with the belt end portion 3a moved in the roller axis direction, and its peripheral edge may form a rectangle, a polygon, or any other closed curve. In this case, the shortest distance D1 from the periphery of the sheet flat surface portion 7a to the shaft of the support roller 52 is longer than the length obtained by adding the thickness of the belt to the radius D2 of the support roller 52. Further, the sheet flat surface portion 7a may be a surface having unevenness or curvature, and the shape thereof is not limited as long as it can be bent when the belt end portion 3a comes into contact therewith.

  Further, the belt contact portion 7 is provided so as to freely rotate about the axis of the support roller 52 in the xy plane shown in FIG. For this reason, when the belt 3 travels in a state where the belt end portion 3a is in contact with the sheet flat surface portion 7a, the belt contact portion 7 is driven by the belt 3 by the frictional force generated between the belt end portion 3a and the belt contact portion 7. Can rotate.

  A member having the support roller 52, the roller shaft 6, the belt contact portion 7, and the belt contact portion holding portion 70 among the members described above is referred to as a roller unit.

  Next, the operation of the belt control device in the image forming apparatus according to the present embodiment will be described with reference to FIGS. When the drive roller 51 is rotated by a drive source (not shown), the belt 3 travels as the drive roller 51 rotates, and the support roller 52 that bridges the belt 3 rotates as the belt 3 travels. At this time, the belt 3 may move in the roller axis direction (z direction shown in FIG. 2) because, for example, the plurality of rollers are not parallel to each other. When the belt end 3a abuts against the sheet flat surface portion 7a of the belt contact portion 7 as the belt 3 moves in the roller axis direction, the belt contact portion 7 is flexible, and thus the force received from the belt end portion 3a is illustrated. 3 is bent in the direction indicated by the arrow F1. And the belt contact part 7 tries to return to the direction (direction shown by arrow F2 of FIG. 3) which returns bending by elastic force. For this reason, a force is applied in a direction to return to the original position with respect to the belt 3 that applies the axially outward force to the belt contact portion 7, and the belt 3 together with the belt contact portion 7 returns to the original position. Trying to return. For this reason, it is possible to suppress the movement of the belt 3 in the axial direction.

  The case where the belt contact portion 7 is not provided will be described. FIG. 5 is a diagram showing a configuration in which a flange 81 is provided at an end of a roller 82 around which a belt 80 is stretched in a conventional belt control device. As shown in FIG. 5, the end of the belt 80 abuts against the flat portion 81a of the flange 81, and the axially outward force of the roller 82 and the axially inward force of the roller 82 due to the reaction force from the flat portion 81a. In response, the load due to the end of the belt 80 abutting against the flat surface portion 81a increases. Further, the belt 80 may ride on the flange 81. For this reason, the belt 80 is damaged from cracks at the ends of the belt 80, and the belt 80 is damaged. By using a flexible material for the belt contact portion 7 as in the present embodiment, the load applied to the belt end portion 3a by the belt contact portion 7 can be suppressed, and cracks and cracks from the belt end portion 3a can be suppressed. It is possible to prevent the belt from being damaged due to the occurrence of this.

  Furthermore, in the conventional belt control device, when the belt 80 hits the flat surface portion 81 a of the flange 81 and travels while contacting the flange 81 at the end portion, the end portion of the belt 80 may get over the flange 81. Here, a case where the end of the belt 80 gets over the flange 81 in the conventional belt control device will be described. FIG. 6 is a view of the configuration shown in FIG. 5 as viewed from the center side of the roller 82 in the axial direction of the roller 82 (z direction shown in FIG. 5).

  As shown in FIG. 6, as the roller rotates in the direction indicated by arrow E, the belt moves in the direction indicated by arrow D. At this time, a frictional force acts on the belt in the direction of the diameter of the roller, so that the end of the belt warps as shown by the dotted line in FIG. When the warpage is large, the end portion of the belt 80 gets over the flange 81 as shown in FIG. 5, causing the belt 80 to be damaged.

  The belt end portion 3a warped in this manner is returned to the original position while suppressing the load that the belt end portion 3a receives from the belt contact portion by providing the flexible belt contact portion 7 in this embodiment. Can do. The operation will be described next.

  The belt contact portion 7 of the present embodiment is provided by fixing the central portion by the belt contact portion holding portion. Accordingly, the belt contact portion 7 shown in FIG. 2 is more likely to bend in the peripheral portion than the central vicinity portion (hereinafter referred to as the central portion), and the load caused by the contact of the greatly warped belt end 3a is reduced. This can be reduced as compared with the case of contacting the vicinity of the central portion of the contact portion 7. Further, since the peripheral portion of the belt contact portion 7 is more easily bent than the central portion, the force for returning the warped belt end portion 3a is larger than the vicinity of the central portion, and the belt 3 moved greatly in the axial direction by warping up. Can be returned to the original position.

  In this embodiment, each part of the belt control device is provided at the end of the support roller 52. However, any one of two or more of the drive roller 51 and the support rollers 52, 53, and 54 is provided at the end of the roller. Each part of the belt control device may be provided. In addition, a belt control device may be provided at both ends of one or more of the driving roller 51 and the supporting rollers 52, 53, and 54.

  Further, when the belt travels in the traveling direction with the belt end portion 3 a in contact with the seat flat surface portion 7 a, the belt contact portion 7 causes the belt abutting portion 7 of the belt 3 to move by the frictional force generated between the belt end portion 3 a and the seat flat surface portion 7 a. Rotates following driving. As a result, the load received by the belt end 3a due to the frictional force can be reduced, and it is possible to prevent the belt 3 from being damaged and the seat flat surface portion 7a from being worn.

  FIG. 4 is a view of the belt contact portion 7 and the support roller 52 as seen from the z direction. Since the portion of the belt contact portion 7 that comes into contact with the belt 3 stretched around the support roller 52 when it moves in the roller axial direction may be flexible, the belt contact portion 7 as a whole is flexible. As shown in FIG. 4, the peripheral portion 71 of the belt contact portion 7 that can contact the belt end 3a is realized by a flexible material, and the center where the belt end 3a does not contact is realized. The portion 72 may be realized by an inflexible material.

DESCRIPTION OF SYMBOLS 1 Photoconductor 3 Intermediate transfer belt 6 Roller shaft 7 Belt contact part 7a Sheet plane part 8 Charging device 9 Exposure device 10 Development device 11 Transfer roller 12 Cleaning device 14 Paper feed device 15 Paper feed roller 16 Registration roller pair 17 Secondary transfer Roller 18 Fixing device 19 Paper discharge roller pair 20 Belt cleaning device 21 Cleaning blade 51 Driving roller 52 Support roller 53 Support roller 54 Support roller 71 Peripheral portion 72 Center portion

JP 2006-78612 A

Claims (6)

A belt control device that controls movement of the belt in the axial direction of a belt that is stretched over a plurality of rollers and travels with the rotation of the rollers,
A belt contact portion in contact with an end portion of the belt at at least one end portion of at least one of the plurality of rollers;
The belt control device according to claim 1, wherein the belt contact portion is flexible. The belt control device according to claim 1,
The belt contact portion is
A plane portion perpendicular to the axial direction;
The shortest distance from the peripheral edge of the flat portion to the roller shaft is longer than a length obtained by adding the thickness of the belt to the radius of the roller. The belt control device according to claim 1 or 2,
The belt control device characterized in that the belt contact portion rotates following the belt. The belt control device according to any one of claims 1 to 3,
A belt control device having belt contact portions at both ends of the one roller. A roller unit used in a belt control device that controls movement of the belt in the axial direction of a belt that is stretched around a plurality of rollers and travels with rotation of the plurality of rollers,
At least one end of at least one of the plurality of rollers has a belt contact portion in contact with the end of the belt;
The roller unit, wherein the belt contact portion is flexible. An image forming apparatus comprising the belt control device according to claim 1 or the roller unit according to claim 5.

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