JP2020154287A - Belt device, belt skew control device, roller unit, and image forming apparatus - Google Patents

Abstract

To provide a belt device that prevents deterioration of a belt facing part that faces an end face of a belt, a belt skew control device, a roller unit, and an image forming apparatus.SOLUTION: A belt device comprises: a belt 3 that is stretched over a plurality of rollers and runs with the rotation of the plurality of rollers; and a belt facing part 300 that faces an end face 3a of the belt in the axial direction of the roller. The belt facing part 300 has a plane part 30a that has a plane orthogonal to the axial direction of the roller, and a separation part 30b that is arranged outside the plane part in the radial direction of the roller, and has a surface separated from the end face of the belt farther than the plane part in the axial direction of the roller.SELECTED DRAWING: Figure 5

Description

The present invention relates to a belt device, a belt-side control device, a roller unit, and an image forming device.

Patent Document 1 describes a belt provided on both sides of the shaft end of the driven roller 2 so as to be able to contact the belt 3 and to detect the deviation of the belt 3 rotatably supported independently of the driven roller 2. A belt drive device including the lean detection member 5 is described.

Patent Document 2 describes a fixing device in which the fixing belt end 101a of the fixing belt 101 is brought into contact with the brim portion 111a provided at the end of the belt movement following member 111.

An object of the present invention is to provide a belt device, a belt approach control device, a roller unit, and an image forming device that suppress deterioration of a belt facing portion facing an end surface of a belt.

The belt device, the belt proximity control device, the roller unit, and the image forming device in the present invention include a belt that is hung on a plurality of rollers and travels with the rotation of the plurality of rollers, and a belt that faces the end faces of the belts in the axial direction of the rollers. A flat surface portion having a flat surface orthogonal to the axial direction of the roller, and a flat surface portion having a flat surface orthogonal to the axial direction of the roller, and a flat surface portion having an opposing portion, and a flat surface portion outside the flat surface portion in the radial direction of the roller, and a belt rather than the flat surface portion in the axial direction of the roller. With a separator having a surface away from the end face of the.

According to the present invention, it is possible to provide a belt device, a belt approach control device, a roller unit, and an image forming device that suppress deterioration of a belt facing portion facing the end face of the belt.

It is a schematic block diagram of an example of the image forming apparatus which concerns on this embodiment. It is a figure which shows the belt approach control device which concerns on this embodiment. It is a figure which shows the belt approach control device which concerns on this embodiment. It is a figure which shows the XY cross section of the belt approach control device shown in FIG. It is a figure explaining the belt facing part of the belt approach control device which concerns on this embodiment. It is a figure which shows the modification of the belt-side control device which concerns on this embodiment. It is an enlarged view of the modification shown in FIG.

Hereinafter, embodiments 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, and the image forming apparatus shown here has four photoconductors 1a, 1b, 1 to 4 in a housing of the main body thereof. 1c and 1d are provided. Similarly, the image forming apparatus includes four charging devices 8a, 8b, 8c, 8d, four developing devices 10a, 10b, 10c, 10d, four transfer rollers 11a, 11b, 11c, 11d, and four cleaning devices 12a. It includes 12b, 12c, and 12d. Toner images of different colors are 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. Toner.

An intermediate transfer belt 3 configured as an intermediate transfer body is provided facing the first to fourth photoconductors 1a, 1b, 1c, and 1d, and each photoconductor 1a, 1b, 1c, and 1d of the intermediate transfer belt 3 It is in contact with the surface. The intermediate transfer belt 3 is bridged over a drive roller 51 and support rollers 52, 53, 54. Reference numeral 31 is a portion of the intermediate transfer belt 3 between the support roller 52 and the drive roller 51, and 32 indicates a portion of the intermediate transfer belt 3 between the support roller 52 and the support roller 53. Any one of the drive roller 51 and the support rollers 52, 53, 54 is called a roller.

A belt tension spring 52a is provided in the vicinity of the support roller 52. It is provided so as to apply an elastic force to the support roller 52 in a direction away from the drive roller 51 and the support roller 53. As a result, the intermediate transfer belt 3 spanned by the support roller 52 is maintained in a tense state without loosening, and the paper can be appropriately conveyed. The belt tension spring 52a is realized by a spring, a leaf spring, rubber, or the like.

The drive roller 51 is rotated by a drive source (not shown), and the rotation of the drive roller 51 causes the intermediate transfer belt 3 to move in the direction indicated by the arrow A. The intermediate transfer belt 3 may have a multi-layer structure or a single-layer structure, but if it has a multi-layer structure, the base layer is made of, for example, a fluororesin, a PVDF sheet, or a polyimide resin having little elongation, and the surface is smooth with a fluororesin or the like. It is preferably covered with a good coat layer. Further, if it is a single layer, it is preferable to use a material such as PVDF, PC, or polyimide.

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

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

A positive polarity transfer voltage, which is opposite to the toner charging polarity of the toner image formed on the photoconductor 1a, is applied to the transfer roller 11a. As a result, a transfer electric field is formed between the photoconductor 1a and the intermediate transfer belt 3, and the toner image on the photoconductor 1a is electrostatically driven on the intermediate transfer belt 3 which is rotationally driven in synchronization with the photoconductor 1a. Transferred. The transfer residual toner adhering to the surface of the photoconductor 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 photoconductor 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 each color are sequentially superimposed on the intermediate transfer belt 3 to which the black toner image is transferred and electrostatically transferred to form a synthetic toner image.

Further, as shown in FIG. 1, a paper feeding device 14 is provided in the lower part of the image forming device, 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-out recording medium P is fed between the drive roller 51 by the resist roller pair 16 and the secondary transfer roller 17 installed facing the drive roller 51. At this time, a predetermined transfer voltage is applied to the secondary transfer roller 17, whereby the synthetic toner image on the intermediate transfer belt 3 is secondarily transferred to the recording medium P.

The recording medium P on which the synthetic toner image is secondarily transferred is conveyed further 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 to the outside of the image forming device via the paper ejection roller pair 19 provided in the paper ejection 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 the cleaning blade 21 is provided so as to scrape off the transfer residual toner adhering 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 method using a conductive fur brush.

Next, a belt-side control device for controlling the movement of the intermediate transfer belt 3 in the axial direction of the roller in the present embodiment will be described. The belt-side control device of the present embodiment is provided on at least one of the rollers included in the image forming apparatus in FIG. 1. In the following description, the intermediate transfer belt 3 is referred to as a belt 3.

The belt-side control device of this embodiment is provided on one side of the support roller 52 of the image forming device in FIG. Therefore, from FIG. 2 onward, one side of the support roller 52 is shown. FIG. 2A is a schematic cross-sectional view of the belt-side control device of the present embodiment.

As shown in FIG. 2A, the belt-side control device has a roller shaft 6 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 having a diameter shorter than that of the support roller 52, and penetrates the support roller 52, the belt abutting portion 30, which will be described later, the shaft displacement portion 41 of the belt position correction portion 40, and the roller shaft support portion 43. ing. Further, the roller shaft 6 is provided integrally with the support roller 52, and is provided so as to penetrate the roller shaft support portion 43. Here, the belt device is composed of the support roller 52, the roller shaft 6, the belt 3, and the belt abutting portion 30.

Further, the belt abutting portion 30 is provided at the end of the support roller 52 so as to be movable in the roller shaft 6 direction, and the shaft of the support roller 52 abuts on the end surface of the belt 3 (referred to as the belt end 3a). (The z direction shown in FIG. 2A; hereinafter referred to as the roller shaft 6 direction). The belt abutting portion 30 may be provided at only one end of the belt 3 in the roller shaft 6 direction, or may be provided at both ends of the belt 3.

The belt abutting portion 30 is made of a material (hardness) softer than the material (hardness) of the belt 3. As a result, the belt end portion 3a is not damaged by hitting the belt abutting portion 30, and the behavior and image of the belt 3 are prevented from being affected.

The belt abutting portion 30 includes a belt facing portion (opposing surface) 300 facing the belt end portion 3a, and the belt facing portion 300 includes a flat surface portion 30a having a plane substantially perpendicular to the roller shaft 6 directions and a support roller. Separation portion having a surface arranged outside the flat surface portion 30a in the radial direction of 52 (X direction shown in FIG. 2A) and separated from the belt end portion 3a from the flat surface portion 30a in the roller axis 6 direction. It has 30b.

The peripheral edge of the flat surface portion 30a forms a circle, and the center of the circle is on the axis of the support roller 52. Further, the flat surface portion 30a functions as a belt end contact portion with which the end of the belt 3 comes into contact when the belt 3 moves outward in the roller shaft 6 direction (direction from the central portion to the end of the support roller 52). To do.

As shown in FIG. 2A, the flat surface portion 30a so that the belt 3 does not ride on the belt abutting portion 30 and come off from the support roller 52 when the belt end portion 3a moves and hits the flat surface portion 30a. The radius Da of the circle formed by the peripheral edge is longer than the length obtained by adding the thickness of the belt 3 to the radius Db of the support roller 52. Support roller 52 with a radius of 8.78 (mm),
When a belt 3 having a thickness of 80 (μm) is used, the belt abutting portion 30 has a radius Da of the peripheral edge of the flat surface portion 30a longer than 8.86 (mm) so as not to interfere with other parts, for example, 9.00. It may be (mm).

The flat surface portion 30a may function as a belt end contact portion, and its peripheral edge may be a rectangle, a polygon, or any other closed curve, instead of a circle. In that case, the distance Da from the axis of the support roller 52 to the shortest peripheral edge of the rectangle or the like is longer than the length obtained by adding the thickness of the belt 3 to the radius of the support roller 52.

Further, the belt abutting portion 30 is not fixed to the support roller 52 and the roller shaft 6, and freely rotates about the same axis as the axis of the support roller 52 in the xy plane shown in FIG. 2 (a). It is provided in. Therefore, when the belt abutting portion 30 travels in a state where the belt 3 is in contact with the flat surface portion 30a, the belt abutting portion 30 is driven by the frictional force between the belt end portion 3a and the flat surface portion 30a to rotate.

Subsequently, the belt position correction unit 40 for returning the belt 3 moved in the roller shaft 6 direction to the original position will be described with reference to FIGS. 2 and 3. FIG. 2B is a diagram showing a state in which the support roller 52 and the roller shaft 6 are tilted in FIG. 2A. FIG. 3 is an overview view of the belt-side control device shown in FIG. 2A as viewed from the z direction.

The belt position correction unit 40 has a shaft displacement portion 41 shown in FIG. 2A, a shaft guide portion 42, a roller shaft support portion 43, a fixing portion 46, and a roller shaft support spring 45 shown in FIG. There is. The shaft displacement portion 41 is provided so as to be in contact with the belt abutting portion 30 inward in the roller shaft 6 direction. Further, when the belt end portion 3a abuts and the belt abutting portion 30 moves outward in the axial direction, the shaft displacement portion 41 is pushed by the belt abutting portion 30 and moves outward in the roller shaft 6 direction. Further, the shaft displacement portion 41 has an inclined surface 41a which is a plane which is inclined outward in the roller shaft 6 direction with the surface parallel to the surface of the belt 3 facing downward in the roller shaft 6 direction. .. Further, since the roller shaft 6 described above penetrates the shaft displacement portion 41, it moves with the movement of the shaft displacement portion 41 in the x-axis direction.

Further, as shown in FIG. 2A, a shaft guide portion 42 is provided in contact with the inclined surface 41a of the shaft displacement portion 41. The shaft guide portion 42 is in contact with the inclined surface 41a of the shaft displacement portion 41 at the shaft displacement portion contact portion 42a, which is a part thereof. Further, even if the roller shaft 6 and the shaft displacement portion 41 move, the shaft guide portion 42 is fixed so as not to move. With such a configuration, when the shaft displacement portion 41 moves outward in the roller shaft 6 direction, the position of the inclined surface 41a in contact with the shaft displacement portion contact portion 42a shifts upward as shown in FIG. 2B. The roller shaft 6 penetrating the shaft displacement portion 41 and the shaft displacement portion 41 is tilted.

Further, a fixing portion 46 for fixing the shaft guide portion 42 is provided outside the roller shaft 6 direction of the shaft guide portion 42, and a roller shaft support portion 43 is provided outside the roller shaft 6 direction of the fixing portion 46. Here, the details of the roller shaft support portion 43 and the fixing portion 46 will be described with reference to FIG.

As shown in FIG. 3, the roller shaft support portion 43 is provided so that the roller shaft 6 penetrates. Therefore, when the roller shaft 6 is tilted downward with its end portion along with the shaft displacement portion 41, the roller shaft support portion 43 is in the direction of arrow a shown in FIG. 3 along an arc centered on the support center portion 43a. Tilt to. Further, the roller shaft support portion 43 is connected to a fixing portion 46 that does not move with the movement of the roller shaft 6 by a roller shaft support spring 45. The roller shaft support spring 45 is an example of an elastic body, and a leaf spring, rubber, or the like may be used instead of the spring.

Among the above-mentioned members, a member having a support roller 52, a roller shaft 6, a belt abutting portion 30, and a belt position correction portion 40 is referred to as a roller unit. Further, a portion having the roller shaft 6 and the roller shaft support portion 43 is referred to as a shaft displacement portion holding portion.

Next, the operation of the belt-side control device in the image forming apparatus of the present embodiment will be described. When the drive roller 51 of the image forming apparatus is rotated by the drive source, the belt 3 travels in the y direction (hereinafter referred to as the traveling direction) shown in FIG. 2A along with the rotation of the driving roller 51, and the belt 3 The support roller 52 that bridges the belt 3 rotates as the vehicle travels. At this time, the belt 3 may move in the roller shaft 6 direction, for example, because the plurality of rollers are not parallel to each other. When the belt 3 moves outward in the roller shaft 6 direction and the belt end portion 3a abuts on the flat surface portion 30a, the belt 3 travels in the traveling direction with the belt end portion 3a in contact with the flat surface portion 30a.

On the other hand, when the belt end portion 3a abuts on the belt abutting portion 30, the belt abutting portion 30 moves outward in the roller shaft 6 direction. When the belt abutting portion 30 moves outward in the roller shaft 6 direction, a force is applied to the shaft displacement portion 41 outward in the roller shaft 6 direction. When the shaft displacement portion 41 tries to move outward in the six directions of the roller shaft by this force, the position of the inclined surface 41a in contact with the shaft displacement portion contact portion 42a of the shaft guide portion 42 is changed as shown in FIG. 2 (b). It shifts upward and tilts. Then, as the shaft displacement portion 41 is tilted, the roller shaft 6 penetrating the shaft displacement portion 41 is tilted.

Here, the movement of the belt 3 over the plurality of rollers in the roller shaft 6 direction will be described in detail. Here, for the sake of simplicity, the operation of the belt 3 of the portion spanning the support roller 52 and the support roller 53 will be described.

When the belt 3 moves in the direction of the roller shaft 6 and hits the belt abutting portion 30, the shaft displacement portion 41 moves outward in the direction of the roller shaft 6 and the roller shaft 6 and the support roller 52 are tilted. This operation will be specifically described.

As shown in FIG. 2A, when the belt end portion 3a abuts on the flat surface portion 30a of the belt abutting portion 30, the belt abutting portion 30 moves outward in the roller shaft 6 direction. Since the shaft displacement portion 41 is provided so as to come into contact with the belt abutting portion 30 on the outer side in the axial direction of the belt abutting portion 30, the roller shaft 6 with respect to the shaft displacement portion 41 due to the movement of the belt abutting portion 30. A force is applied outward in the direction. When the shaft displacement portion 41 moves outward in the six directions of the roller shaft by this force, the position of the inclined surface 41a in contact with the shaft displacement portion contact portion 42a of the shaft guide portion 42 moves upward as shown in FIG. 2 (b). Displace and tilt. Then, as the shaft displacement portion 41 is tilted, the end portion of the roller shaft 6 penetrating the shaft displacement portion 41 moves in the + x direction (the direction toward the lower side in FIG. 2B).

When the end of the roller shaft 6 moves in the + x direction, the support roller 52 through which the roller shaft 6 penetrates tilts. Here, if the support roller 52 is tilted more than the tilt of the support roller 53, the support roller 52 and the support roller 53 are subjected to a force that forms a relatively opposite tilt due to the tension of the belt 3. When the support roller 52 and the support roller 53 form relatively opposite inclinations, the belt 3 moves in the −z direction and returns to the original position.

In order to correct the position of the belt 3 as described above, the shaft displacement portion 41 must be in contact with the shaft displacement portion contact portion 42a of the shaft guide portion 42 on the inclined surface 41a as described above. Here, the principle for the shaft displacement portion 41 to receive a force in the direction of the shaft guide portion 42 will be described so that the shaft displacement portion 41 is in contact with the shaft guide portion 42.

As shown in FIG. 3A, tensions F11 and tensions F12 are generated on the belt 3 running over the support rollers 52. Therefore, the resultant force F of the tension F11 and the tension F12 is applied to the support roller 52. Therefore, a resultant force F is applied to the roller shaft support portion 43 via the roller shaft 6. Here, the roller shaft support portion 43 is provided so as to freely rotate around the support center portion 43a. Further, the support center portion 43a is provided on the side opposite to the shaft displacement portion contact portion 42a with respect to the direction in which the resultant force F acts from the shaft of the support roller 52. Therefore, a rotational moment F2 is applied to the roller shaft support portion 43 so that a force is applied in the direction of bringing the shaft displacement portion 41, which moves with the movement of the roller shaft support portion 43 and the roller shaft 6, closer to the shaft displacement portion contact portion 42a. appear. That is, a force is applied to the roller shaft 6 provided so as to penetrate the roller shaft support portion 43 and the shaft displacement portion 41 penetrating the roller shaft 6 in a direction approaching the shaft displacement portion abutting portion 42a. Therefore, the shaft displacement portion 41 can be kept in contact with the shaft guide portion 42 at the shaft displacement portion contact portion 42a.

In the image forming apparatus of the present embodiment, the rotational moment F2 generated in the roller shaft support portion 43 changes by changing the position of the roller that bridges the belt 3. Specifically, for example, when an image is formed in a black monochromatic mode using only black toner, the belt 3 uses cyan, magenta, and yellow toner as shown in FIG. 3 (b). The belt 3 is bridged so that only the black-colored photoconductor 1a is in contact with the photoconductors 1b, 1c, and 1d for adhesion. On the other hand, when the image is formed in the full color mode using all the black, cyan, magenta, and yellow toners, the photoconductors 1a, 1b, and 1c, as shown in FIG. 3A, The belt 3 is hung so as to be in contact with 1d. In the case of the black monochromatic mode shown in FIG. 3 (b) and the case of the full color mode shown in FIG. 3 (a), the angle formed by the belt 3 bridged to the support roller 52 is different, so that the roller shaft support portion 43 The direction of tension applied to is different.

Here, in the belt position correction device shown in FIG. 3, a case where the support center portion 43a of the roller shaft support portion 43 is installed at a position shifted upward as compared with the case shown in FIG. 3 will be described.

When the support center portion 43a is installed at a position shifted upward as compared with the case shown in FIG. 3, in the black monochromatic mode, the roller shaft support portion 43 approaches the shaft displacement portion contact portion 42a as described above. A rotational moment F2 is applied in the direction. On the other hand, in the full color mode, since the support center portion 43a is on the same side as the shaft displacement portion contact portion 42a with respect to the direction of the resultant force F from the shaft of the support roller 52, the roller shaft support portion 43 has a shaft displacement portion. A rotational moment F2 is applied in a direction away from the contact portion 42a. That is, in the case of the full color mode, the shaft displacement portion 41 is separated from the shaft displacement portion contact portion 42a of the shaft guide portion 42.

In order to solve such a problem, as shown in FIGS. 3A and 3B, the tension of the belt 3 is increased regardless of whether the image forming apparatus operates in the full color mode or the black monochromatic mode. It is necessary to provide the support center portion 43a on the side opposite to the shaft displacement portion contact portion 42a with respect to the direction of the resultant force from the force point of the resultant force F, that is, the direction of the resultant force from the axis of the support roller 52. In a normal image forming apparatus, as shown in FIG. 1, the belt 3 runs between the support roller 52 and the drive roller 51, and runs between the support roller 52 and the support roller 53. Since the magnitude of the tension generated in the portion 32 of the belt 3 is the same, the straight line from the point of force of the resultant force F to the direction of the resultant force bisects the angle formed by the portion 31 of the belt 3 and the portion 32 of the belt 3. It becomes a bisector that divides.

By providing the support center portion 43a in consideration of the above, for example, even if the relative positional relationship between the plurality of rollers changes due to the change between the black monochromatic mode and the full color mode, the shaft displacement portion 41 can be used as the shaft guide portion 42. A force can be applied in the direction of approaching the roller shaft 6, and the roller shaft 6 can be appropriately tilted.

Further, in the present embodiment, since the roller shaft support spring 45 is provided as shown in FIG. 3, a force is applied to the shaft displacement portion 41 outward in the roller shaft 6 direction to apply the roller shaft 6 outward. When is tilted, the roller shaft support portion 43 is tilted along an arc centered on the support center portion 43a in the direction indicated by the arrow A in FIG. An elastic force acts in the direction of returning the extension of the roller shaft support spring 45 that has been extended by tilting the roller shaft support portion 43. Since the roller shaft support portion 43 tends to return to the original position (direction indicated by the arrow a) due to this elastic force, the roller shaft 6 penetrating the roller shaft support portion 43 tends to be displaced upward. Therefore, when a force is applied to the shaft displacement portion 41 outward in the roller shaft 6 direction as described above, the shaft displacement portion 41 does not separate from the shaft guide portion 42 due to the tension of the belt 3, and the inclined surface 41a It is possible to maintain the state in which the shaft displacement portion 41 is in contact with the shaft displacement portion contact portion 42a of the shaft guide portion 42 at any of the positions.

In this embodiment, as shown in FIG. 2, the shaft displacement portion 41 is provided so as to come into contact with the shaft guide portion 42 below the shaft guide portion 42. As described above, in such a configuration, the shaft displacement portion 41 is directed to the shaft displacement portion 41 in the direction of the shaft displacement portion contact portion 42a so as not to be separated from the shaft displacement portion contact portion 42a of the shaft guide portion 42. You have to make sure that force is applied.

FIG. 4 is a diagram showing an XY cross section of the belt-side control device shown in FIG.

In FIG. 4A, in the portion 3b where the belt 3 is wound around the support roller 52, the linear velocity of the belt abutting portion 30 is the same as the linear velocity of the belt 3.

FIG. 4B is a diagram for explaining the linear velocity of the belt abutting portion 30 when the support roller 52 rotates in the A direction in the figure. In FIG. 4B, v1 indicates the linear velocity on the side close to the rotation center of the belt abutting portion 30 in the radial direction of the support roller 52, and v2 indicates the linear velocity of the belt abutting portion 30 in the radial direction of the support roller 52. The line speed on the side far from the center of rotation is shown, and the line speed v2> the line speed v1.

In FIG. 4C, point A indicates a position where the outer peripheral surfaces of the belt 3 and the belt abutting portion 30 intersect in the roller axis 6 direction of the support roller 52, and point B indicates the outer circumference of the belt 3 and the support roller 52. Indicates the point of contact with the surface. At point B, as shown in FIG. 4 (a), there is no difference in linear velocity between the belt abutting portion 30 and the belt 3, but at point A, as shown in FIG. 4 (b), there is more than at point B. The linear speed of the belt abutting portion 30 is high. Therefore, at point A, a linear speed difference between the belt abutting portion 30 and the belt 3 occurs, and as shown in FIG. 2, the belt end portion 3a comes into contact with the belt facing portion 300, so that the belt facing portion 300 Is easy to scrape. Then, the longer the distance between the points A and B, the larger the difference in linear speed between the belt abutting portion 30 and the belt 3 at the point A, and the belt facing portion 300 is easily scraped.

FIG. 5 is a diagram illustrating a belt facing portion of the belt approach control device according to the present embodiment.

In FIG. 5A, the outer diameter side of the separation portion 30b corresponds to the point A in FIG. 4C, but as described in FIG. 2, the separation portion 30b is from the flat surface portion 30a in the roller shaft 6 direction. Also has a surface away from the belt end 3a, so that it does not come into contact with the belt end 3a and is not scraped due to the difference in linear velocity with the belt end 3a.

The separation portion 30b has an inclined surface as a surface that intersects the radial direction of the support roller 52 and the roller shaft 6 direction.

Here, if only to eliminate the linear velocity difference from the belt end portion 3a, it is conceivable to form the entire surface of the belt facing portion 300 with an inclined surface such as the separating portion 30b. In that case, the belt end portion By coming into contact with the edge of 3a, the inclined surface is easily scraped.

That is, in the present embodiment, the flat surface portion 30a having a flat surface orthogonal to the roller shaft 6 direction and the support roller 52 are arranged outside the flat surface portion 30a in the radial direction and the belt from the flat surface portion 30a in the roller shaft 6 direction. By having a separation portion 30b having a surface separated from the end portion 3a, the flat surface portion 30a suppresses scraping caused by the edge of the belt end portion 3a, and the separation portion 30b suppresses the linear speed difference from the belt end portion 3a. Suppresses scraping caused by.

Further, as shown in FIG. 5A, the size t30a of the flat surface portion 30a is larger than the thickness t3 of the belt 3 in the radial direction of the support roller 52. As a result, even if the wound portion is small, the belt end portion 3a is prevented from moving in the radial direction of the support roller 52 and being separated from the flat surface portion 30a.

Further, since the separating portion 30b has an inclined surface, even if the belt end portion 3a moves in the radial direction of the support roller 52 and separates from the flat surface portion 30a, it is easy to return from the separating portion 30b to the flat surface portion 30a. ..

In FIG. 5B, the boundary portion 30R between the flat surface portion 30a and the separation portion 30b is formed in an R shape (arc shape), and in FIG. 5C, the surface of the separation portion 30b has an R shape (arc shape). Shape) Includes portion 30bR.

With these configurations, the belt end portion 3a can be gently brought into contact with the belt facing portion 300, so that the belt facing portion 300 is less likely to be scraped.

FIG. 6 is a diagram showing a modified example of the belt-side control device according to the present embodiment.

In this modification, the belt abutting portion 30 has a small diameter tubular portion 30c that protrudes inward in the roller shaft 6 direction from the belt abutting portion 30.

The outer diameter of the small-diameter tubular portion 30c is formed to be slightly smaller than the outer diameter of the support roller 52 for axial movement, and there is a slight space between the outer diameter of the belt 3 and the inner diameter of the belt 3 hung on the support roller 52. It is formed. It should be noted that this space is a gap that can be slidably contacted and supported when the belt 3 is moved.

FIG. 7 is an enlarged view of the modified example shown in FIG.

In FIG. 7, in the radial direction of the support roller 52, the distance L30a from the axis center of the roller shaft 6 to the boundary portion between the flat surface portion 30a and the separation portion 30b is the distance L3 from the axis center of the roller shaft 6 to the surface of the belt 3. Greater than.

That is, since the distance L30a and the distance L3 each include the small diameter tubular portion 30c, excluding this, the size of the flat surface portion 30a> the thickness of the belt 3 + the inner diameter and the small diameter of the belt 3 in the radial direction of the support roller 52. It is the distance of the space between the outer diameters of the tubular portion 30c. Preferably, the size of the flat surface portion 30a = the thickness of the belt 3 × 2. Further, the relationship between the distance L30a and the distance L3 is established not only when the belt 3 is stopped but also when the belt 3 is moved.

The belt deviation control device in the present embodiment can be applied not only to the intermediate transfer belt 3 but also to belts such as a direct transfer belt and a fixing belt that generate deviation.

In the present embodiment, it is assumed that the belt-side control device is provided at the end of the support roller 52, but the belt-side control device is provided at the end of any two or more rollers of the drive roller 51 and the support rollers 52, 53, 54. May be provided.

Further, in the present embodiment, belt-side control devices may be provided at both ends of one or more rollers of the drive roller 51 and the support rollers 52, 53, 54.

Further, in the present embodiment, the belt end support portion 7 and the belt abutting portion 30 may be separate members or may be provided integrally.

Further, in the present embodiment, the shaft displacement portion 41 is an inclined surface 41a which is a plane which is inclined outward in the roller shaft 6 direction with the outer side in the roller shaft 6 direction downward with respect to a surface parallel to the surface of the belt 3. Is held above the axis of the support roller 52. However, the inclined surface 41a, which is a plane that is inclined outward in the roller shaft 6 direction with the outer side in the roller shaft 6 direction upward with respect to the surface parallel to the surface of the belt 3, is placed below the axis of the support roller 52. You may have.

Further, in the present embodiment, when the belt 3 travels in the traveling direction with the belt end portion 3a in contact with the flat surface portion 30a, the belt abutting portion 30 is generated by the frictional force generated between the belt end portion 3a and the flat surface portion 30a. Rotates according to the running of the belt 3. As a result, the load received by the belt end portion 3a due to the frictional force can be reduced, and it is possible to prevent the belt 3 from being damaged and the flat surface portion 30a from being worn.

1 Photoreceptor 3 Intermediate transfer belt 3a Belt end (belt end face)
6 Roller shaft 7 Belt end support 8 Charging device 9 Exposure device 10 Developing device 11 Transfer roller 12 Cleaning device 14 Feeding device 15 Feeding roller 16 Resist roller pair 17 Secondary transfer roller 18 Fixing device 19 Paper ejection roller pair 20 Belt cleaning device 21 Cleaning blade 30 Belt abutting part 300 Belt facing part (opposing surface)
30a Flat part 30b Separation part 40 Belt position correction part 41 Shaft displacement part 41a Inclined surface 42 Shaft guide part 42a Shaft displacement part contact part 43 Roller shaft support part 43a Support center part 45 Roller shaft support spring 46 Fixing part 51 Drive roller 52 Support roller 53 Support roller 54 Support roller

Japanese Unexamined Patent Publication No. 11-116089 Japanese Unexamined Patent Publication No. 2012-198293

Claims (8)

It is provided with a belt that is hung on a plurality of rollers and travels with the rotation of the plurality of rollers, and a belt facing portion that is provided on one of the plurality of rollers and faces the end surface of the belt in the axial direction of the rollers. It ’s a belt device,
The belt facing portion is
A flat surface portion having a flat surface orthogonal to the axial direction of the roller,
A belt device having a separating portion that is arranged outside the flat surface portion in the radial direction of the roller and has a surface that is separated from the end surface of the belt from the flat surface portion in the axial direction of the roller. The belt device according to claim 1, wherein the flat surface portion is larger than the thickness of the belt in the radial direction of the roller. The belt device according to claim 1 or 2, wherein the separating portion has a surface that intersects the radial direction of the roller and the axial direction of the roller. The belt device according to claim 3, wherein the intersecting surfaces include an R-shaped portion. The belt device according to any one of claims 1 to 4, wherein the boundary portion between the flat surface portion and the separation portion is formed in an R shape. The belt device according to any one of claims 1 to 5 is provided, and the belt is movable in the axial direction by moving in the axial direction of the roller, and is inclined with respect to a surface parallel to the surface of the belt. Axial displacement part having an inclined surface and
A belt-oriented control device further provided with a shaft guide portion installed so as to face the inclined surface. A roller unit used in a belt device including a belt that is hung on a plurality of rollers and travels with the rotation of the plurality of rollers.
A belt facing portion provided on one of the plurality of rollers and facing the end face of the belt in the axial direction of the roller is provided.
The belt facing portion is
A flat surface portion orthogonal to the axial direction of the roller and
A roller unit having a separating portion that is arranged outside the flat surface portion in the radial direction of the roller and is arranged apart from the flat surface portion and the end surface of the belt in the axial direction of the roller. An image forming apparatus having the belt device according to any one of claims 1 to 6 or the roller unit according to claim 7.