JP5979484B2 - Belt control device, roller unit, and image forming apparatus - Google Patents

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 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 stretched over at least two rollers provided in parallel to each other, and are configured to run as the rollers rotate. However, a plurality of rollers may not be parallel to each other due to deterioration 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 moves in the axial direction of the roller (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.

  A belt position correction technique for returning the belt moved in the roller axis direction to the original position is known. For example, Patent Document 1 describes a technique for correcting meandering generated in a paper transport belt by providing a rotating body having an inclined surface and a fixing member. Here, a technique for correcting meandering described in Patent Document 1 will be described with reference to FIGS. 7A and 7B. 7 (1) and 7 (2) are diagrams showing a meandering correction device described in Patent Document 1. FIG. In the meandering correction device, a rotating body 93 having an inclined surface 92 is provided at one end of a meandering correction roll 91 that stretches the paper conveyance belt 90. Further, a fixing member 94 that comes into contact with the outer peripheral surface of the rotating body 93 is provided. In the case where no meandering occurs on the paper conveying belt 90, the rotating bodies 93 at both ends are kept in contact with the fixing member 94 as shown in FIG.

  When meandering occurs in the paper transport belt 90, the end of the paper transport belt 90 presses the single rotating body 93. The pressed rotating body 93 moves outward in the axial direction of the meandering correction roll 91. When the rotating body 93 moves outward in the axial direction, as shown in FIG. 7B, the rotating body 93 comes into contact with the fixed member 94 and is pushed up by the inclined surface 92. As a result, the end of the meandering correction roll 91 is pushed up, and the paper transport belt 90 moves in the direction opposite to the meandering direction, so that the position of the paper transport belt 90 is corrected.

However, in the technique described in Patent Document 1, as shown in FIGS. 7A and 7B, the meandering correction roll 91 is in contact with the rotating body 93 at the end and is pressed by the meandering paper conveyance belt 90. The rotating body 93 is provided so as to move outward in the axial direction. In this case, the meandering correction roll 91 may move outward in the axial direction due to deterioration of the member on which the meandering correction roll 91 is installed. When the meandering correction roll 91 moves outward in the axial direction, the meandering correction roll 91 presses the rotating body 93 outward in the axial direction even if the paper transport belt 90 does not press the rotating body 93. Alternatively, the meandering correction roll 91 presses the rotating body 93 outward in the axial direction with a force larger than the force with which the sheet conveying belt 90 presses the rotating body 93.
As a result, even when the paper conveying belt 90 is not meandering, the rotating body 93 moves outward in the axial direction and the end of the meandering correction roll 91 is pushed up. Alternatively, the rotary body 93 moves outward in the axial direction more than necessary to correct the meandering of the paper transport belt 90 and the end of the meandering correction roll 91 is pushed up. For this reason, the sheet conveying belt 90 is returned more than necessary, and there is a problem that correction cannot be performed accurately.

In order to solve the above-described problem, in the present invention, the movement of a belt that is stretched over a plurality of rollers and travels with the rotation of the plurality of rollers is controlled in the axial direction of at least one of the plurality of rollers. A belt control device that has an inclined surface that is inclined with respect to a plane parallel to the surface of the belt, and the axial displacement that moves in the axial direction when the belt moves in the axial direction of the roller And a shaft guide portion fixedly installed so as to be in contact with the inclined surface, and a gap larger than the axial backlash on the roller installation between the roller and the shaft displacement portion And the inclined surface is inclined so as to face obliquely upward and lower toward the outer side in the axial direction, and the shaft displacement portion is pushed by the belt moving outward in the axial direction, thereby the shaft. Ga It is intended to tilt as down while in contact with the de-section in the inclined surface, to hold the state of contact between the guide portion and the inclined surface is provided means for providing a force for displacing the shaft displacement portion upward Features.

  According to the present invention, there is an inclined surface that is inclined with respect to a plane parallel to the surface of the belt, the axial displacement portion that moves in the axial direction when the belt moves in the axial direction of the roller, and the inclined A fixed portion that is fixedly installed so as to be in contact with a surface, a gap is formed between the roller and the shaft displacement portion, and the shaft displacement portion moves outward in the axial direction. By being pushed by the belt, the fixing portion is inclined while being in contact with the inclined surface, so that the belt position can be accurately corrected.

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 for demonstrating the clearance gap part of the belt control apparatus which concerns on this embodiment. It is a figure for demonstrating the movement to the roller axial direction of a belt. It is a figure showing 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. Note that any of the drive roller 51 and the support rollers 52, 53, and 54 is referred to as a roller.

  A belt tension spring 52 a is provided in the vicinity of the support roller 52. The belt tension spring 52 a is provided so as to give 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 stretched around the support roller 52 is held tightly without being loosened, and the paper can be conveyed appropriately. The belt tension spring 52a is an example of an elastic body, and is realized by a spring, a leaf spring, rubber, or the like.

  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.

  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, a belt control device for controlling the movement of the intermediate transfer belt 3 in the axial direction of the roller in this embodiment will be described. The belt control device of this embodiment is provided on at least one of the rollers of the image forming apparatus in FIG. 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. 2A is a schematic cross-sectional view of the belt control device of the present embodiment. FIG. 2 (2) is a diagram illustrating a state in which the support roller 52 and the roller shaft 6 are inclined in FIG. 2 (1). FIG. 3 is an overview of the belt control device shown in FIG. 2A as viewed from the z direction.

  As shown in FIG. 2 (1), 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 shaft displacement portion 41 described later, and a roller shaft support portion 43. The roller shaft 6 is provided so as to move integrally with the support roller 52 and the roller shaft support portion 43. Further, the end portion of the support roller 52 extends outwardly from the direction of the axis of the support roller 52 (the z direction shown in FIG. 2 (1), hereinafter referred to as the roller axial direction) from the central portion of the support roller 52 to the end portion. In the direction of heading, the shaft displacement portion 41 is provided so as to be movable in the roller shaft direction. The shaft displacement portion 41 has a belt abutting portion 41a against which an end portion (referred to as a belt end portion 3a) of the belt 3 moved outward in the roller axial direction abuts. The belt abutting portion 41 a has a flat portion 41 b that is a flat surface that is substantially perpendicular to the axial direction of the support roller 52. The periphery of the flat portion 41 b forms a circle, and the center of the circle is on the axis of the support roller 52.

  As shown in FIG. 2 (1), when the belt end portion 3a moves and hits the flat surface portion 41b, the belt 3 runs on the belt abutting portion 41a and does not come off the support roller 52. The radius Da of the circle formed by the peripheral edge is configured to be longer than the length obtained by adding the thickness of the belt 3 to the radius Db of the support roller 52. When the support roller 52 having a radius of 8.78 (mm) and the belt 3 having a thickness of 80 (μm) are used, the belt abutting portion 41a has a radius Da of 8 on the periphery of the flat portion 41b so as not to interfere with other components. It may be longer than .86 (mm), for example, 9.00 (mm).

  The flat surface portion 41b may be any surface as long as the belt 3 moved in the roller axis direction abuts, and the peripheral edge thereof is not a circle but may be a rectangle, a polygon, or any other closed curve. In this case, the distance from the axis of the support roller 52 to the periphery of the rectangle or the like is longer than the length of the radius of the support roller 52 plus the thickness of the belt 3. Further, the flat portion 41b may be a surface having unevenness or curvature, and any shape can be used as long as it functions as a belt contact portion.

  Further, the belt abutting portion 41a is not fixed to the support roller 52 and the roller shaft 6, but freely rotates around the same axis as the support roller 52 in the xy plane shown in FIG. Is provided. For this reason, when the belt 3 travels in contact with the flat surface portion 41b, the belt abutting portion 41a rotates according to the travel of the belt 3 by the frictional force with the belt end portion 3a.

  Between the end portion of the support roller 52 and the belt abutting portion 41a, a belt end portion support portion 7 configured in a cylindrical shape is provided. The belt end support portion 7 has its axis coaxial with the axis of the support roller 52, and its radius Dc is shorter than the radius Db of the support roller 52. Thus, a gap (hereinafter referred to as a gap portion 31a) is provided between the belt 3 and the side surface of the belt end portion support portion 7. The belt end portion support portion 7 supports the belt end portion 3a in order to prevent the belt end portion 3a from being separated from the belt abutting portion 41a and hanging down due to gravity. In addition, as long as the belt edge part support part 7 supports the belt edge part 3a, the shape may be not only a cylinder but a prism, a cube, or any other shape.

  Moreover, the shaft displacement part 41 has the shaft inclination part 41c, and the shaft inclination part 41c is provided so that the belt contact part 41a may be contact | connected. Further, the shaft inclined portion 41c has an inclined surface 41d that is a flat surface that is inclined outwardly in the roller axis direction with respect to a surface parallel to the surface of the belt 3 outward in the roller axis direction. Further, since the above-described roller shaft 6 penetrates the shaft displacement portion 41, the roller shaft 6 can freely move with respect to the shaft displacement portion 41 in the roller shaft direction, and the shaft in the direction perpendicular to the roller shaft direction. It moves together with the displacement part 41.

  Further, as shown in FIG. 2A, a shaft guide portion 42 is provided in contact with the inclined surface 41d of the shaft inclined portion 41c. The shaft guide part 42 is in contact with the inclined surface 41d at the shaft displacement part contact part 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 this configuration, when the shaft displacement part 41 moves outward in the roller axial direction, the position of the inclined surface 41d with which the shaft displacement part contact part 42a contacts is shifted upward as shown in FIG. The roller shaft 6 passing through the displacement portion 41 and the shaft displacement portion 41 is inclined.

  Further, a fixed portion 46 is provided on the outer side of the shaft guide portion 42 in the roller axis direction, and a roller shaft support portion 43 is provided on the outer side of the fixed portion 46 in the roller axis direction. Here, details of the roller shaft support portion 43 and the fixed portion 46 will be described with reference to FIG.

  As shown in FIG. 3, the roller shaft support portion 43 is provided integrally with the roller shaft 6, and as the roller shaft 6 inclines with the outer side in the roller shaft direction downward, the support center portion 43a. Is inclined in the direction of the arrow A shown in FIG. The roller shaft support portion 43 is connected by a fixed portion 46 that does not move with the movement of the roller shaft 6 and a roller shaft support spring 45. As described above, when the roller shaft support portion 43 is inclined in the direction indicated by the arrow A, the roller shaft support spring 45 is extended. When the roller shaft support spring 45 extends, an elastic force is generated in a direction to return the extension, and the roller shaft support portion 43 attempts to return in the direction indicated by the arrow A. 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.

  Further, a gap (hereinafter referred to as a gap portion 31b) is provided between the support roller 52 and the belt end support portion 7 so that the shaft displacement portion 41 does not move due to the axial movement of the support roller 52 shown in FIG. ) Is provided. Here, the length of the gap portion 31b in the roller axial direction will be described with reference to FIGS. 4 (1) and 4 (2). 4 (1) and 4 (2) are diagrams showing the support roller 52, the belt end support portion 7 and the belt abutting portion 41a provided at both ends of the support roller 52. FIG. As shown in FIG. 4A, the length of the support roller 52 in the axial direction is D1, the length of the belt end support portion 7 in the roller axial direction is D2, and is provided at one end of the support roller 52. When the distance D3 between the belt abutting portion 41a and the belt abutting portion 41a provided at the other end is set to D3, the gap portion 31b is provided by making D1 + D2 × 2 shorter than D3. .

  Further, the backlash occurs due to the relationship with a member such as a screw for installing the support roller 52, but the support roller 52 does not contact the belt end support portion 7 when the backlash moves most in the roller axial direction. Thus, the length of the gap portion 31b in the roller axis direction is determined. That is, the length of the gap portion 31b in the roller axis direction is determined so that the support roller 52 does not contact the belt end support portion 7 at a position where the movement of the support roller 52 in the roller axis direction is stopped by the member. The length of the gap 31b in the roller axis direction is preferably about 11.3 (mm) with respect to the support roller 52 having a diameter of 17.45 (mm) and a length of 322 (mm) in the roller axis direction.

  A member having the support roller 52, the roller shaft 6, and the belt position correcting unit 40 among the members described above is referred to as a roller unit. Also, the belt position correction unit 40 includes the shaft displacement unit 41, the shaft guide unit 42, the roller shaft support unit 43, the fixing unit 46, and the roller shaft support spring 45 shown in FIG.

  Next, the operation of the belt control device in the image forming apparatus of this embodiment will be described. When the driving roller 51 of the image forming apparatus is rotated by the driving source, the belt 3 travels in the y direction (hereinafter referred to as the traveling direction) shown in FIG. As the belt 3 travels, the support roller 52 that spans the belt 3 rotates. At this time, the belt 3 may move in the roller axial direction because, for example, the plurality of rollers are not parallel to each other. When the belt 3 moves outward in the roller axis direction and the belt end portion 3a hits the flat surface portion 41b, the belt end 3a applies a force in the roller axial direction outward to the belt abutting portion 41a. Travel in the direction of travel.

  Here, the movement of the belt 3 in the roller axis direction will be described in detail. Here, in order to facilitate the explanation, the operation of the belt 3 in the portion spanning the support roller 52 and the support roller 53 will be described.

  FIGS. 5A and 5B show a state in which the belt 3 is stretched between the support rollers 52 and 53 and the shaft of the support roller 52 and the shaft of the support roller 53 are not parallel to each other. In particular, FIG. 5A shows a state in which the support roller 52 is parallel to the paper surface and the left end portion of the support roller 53 is inclined so as to be closer to the paper surface in the x-axis direction than the right end portion. Has been. Thus, when the belt 3 is inclined at an angle α with respect to the running direction (y-axis direction) because the shaft of the support roller 52 and the shaft of the support roller 53 are not parallel to each other, the belt 3 is in the y-axis direction. When traveling by the distance L, the belt 3 moves by the distance Ltanα in the + z direction (the direction toward the right side in FIG. 5).

  When the belt 3 moves in the roller axis direction and abuts against the shaft displacement portion 41, the shaft displacement portion 41 moves outward in the roller axis direction and the roller shaft 6 and the support roller 52 are inclined. This operation will be specifically described.

  As shown in FIG. 2A, when the belt end portion 3a hits the flat portion 41b of the belt abutting portion 41a, the belt abutting portion 41a moves outward in the roller axial direction. Since the shaft inclined portion 41c is provided so as to contact the belt abutting portion 41a outside the belt abutting portion 41a in the axial direction, the movement of the belt abutting portion 41a causes the axial direction of the roller to move relative to the shaft inclined portion 41c. Power to the outside is given. When the shaft inclined portion 41c is moved outward in the roller axial direction by this force, the position of the inclined surface 41d with which the shaft displacement portion contact portion 42a of the shaft guide portion 42 contacts is shifted upward as shown in FIG. 2 (2). Tilt. Then, with the inclination of the shaft displacement portion 41, the end portion of the roller shaft 6 passing through the shaft displacement portion 41 moves in the + x direction (the direction toward the lower side in FIG. 2 (2)).

  When the end of the roller shaft 6 moves in the + x direction, the support roller 52 through which the roller shaft 6 passes is inclined. FIG. 5B is a view of the state in which the support roller 52 is inclined in FIG. As shown in FIG. 5B, the left end portion of the support roller 52 is inclined so as to be in front of the right end portion in the x-axis direction. Here, when the support roller 52 is inclined more than the inclination of the support roller 53, the support roller 52 and the support roller 53 form an inclination that is relatively opposite to the state shown in FIG. Become. When the support roller 52 and the support roller 53 form a relatively reverse inclination, the belt 3 moves in the −z direction (the direction toward the left side in FIG. 5B) and returns to the original position.

  Specifically, as shown in FIG. 5B, when the traveling direction of the belt 3 is inclined by the angle α ′ due to the inclination of the support roller 52, the belt 3 travels a distance L in the y-axis direction. It moves by a distance of Ltanα ′ in the −z direction, which is the opposite direction to the above-described operation. That is, the belt 3 stretched around the support roller 52 returns inward in the axial direction, and the position of the belt is corrected so that the position of the belt 3 moves in a direction to return to the original position with respect to the roller axial direction. Will be.

  In the above-described operation, since the gap 31b is provided between the support roller 52 and the belt end support portion 7, even if the play occurs and the support roller 52 moves in the roller axial direction, Since the belt end portion support portion 7 is separated, the support roller 52 does not apply an axially outward force to the belt end portion support portion 7 and the belt abutting portion 41a. Therefore, the roller shaft 6 can be inclined only by the force applied by the belt end portion 3a abutting against the belt abutting portion 41a. That is, when the belt 3 moves greatly in the roller axial direction, the force that the belt end portion 3a applies to the belt abutting portion 41a is large, so that the angle α ′ at which the roller shaft 6 tilts increases and the belt 3 moves in the roller axial direction. The distance Ltanα ′ returning inward becomes longer. On the other hand, when the movement of the belt 3 in the roller axis direction is small, the force exerted by the belt end portion 3a on the belt abutting portion 41a is small, so that the angle α ′ at which the roller shaft 6 tilts becomes small, and the belt 3 The distance Ltanα ′ returning inward in the direction becomes shorter. Thus, the distance that the belt 3 returns to the inner side of the roller axis is determined by the magnitude of the movement of the belt 3 outward in the roller axis direction, and appropriate correction can be performed.

  Further, when the belt 3 moves in the roller axial direction and the belt end portion 3a hits the flat surface portion 41b of the belt abutting portion 41a, a portion in the vicinity of the belt end portion 3a (a portion indicated by Q in FIG. 2 (1)). Hereinafter, the vicinity portion Q) receives a force in the roller axial direction outward and a force in the roller axial direction due to the reaction force from the flat surface portion 41b. By receiving these forces, the vicinity Q of the belt end 3a bends toward the gap 31a as shown in FIG.

  In the case of the conventional configuration in which the gap portion 31a is not provided, as shown in FIG. 8, the end portion 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 force from the flat portion 81a. Even when the axial force of the roller 82 due to the reaction force is received, the belt 3 is in close contact with the support roller 52, so there is no room for bending. Therefore, the load due to the end of the belt 80 striking against the flat surface portion 81a is large, causing a crack from the end of the belt 80 and the damage of the belt 80 due to the crack.

  That is, in this embodiment, by providing the clearance 31a between the support roller 52 and the belt abutting portion 41a, the load received when the belt end 3a abuts against the flat portion 41b is reduced, and the belt end 3a or its end is reduced. It is possible to prevent the belt from being broken by causing cracks or cracks in the vicinity Q.

  Further, in the present embodiment, as shown in FIG. 3, since the roller shaft support spring 45 is provided, a force outward in the roller axis direction is applied to the shaft displacement portion 41 to cause the roller shaft 6 to move. When tilted, the roller shaft support portion 43 tilts along an arc centered on the support center portion 43a in the direction indicated by the arrow A in FIG. An elastic force is generated in a direction to return the extension of the roller shaft support spring 45 extended by the inclination of the roller shaft support portion 43. Due to this elastic force, the roller shaft support portion 43 tends to return to the original position (the direction indicated by the arrow A), so that the roller shaft 6 integrated with the roller shaft support portion 43 tends to be displaced upward. For this reason, when a force is applied to the shaft displacement portion 41 in the roller axial direction as described above, the shaft displacement portion 41 does not leave the shaft guide portion 42 due to its own weight, and any one of the inclined surfaces 41d. In this position, it is possible to keep the shaft guide portion 42 in contact with the shaft displacement portion abutting portion 42a.

  As described above, in the present embodiment, no force is applied to the shaft displacement portion 41 due to the movement of the support roller 52 in the axial direction caused by play, and the shaft displacement portion due to the movement of the belt 3 in the axial direction. Since the belt position is corrected based only on the force applied to the belt 41, the belt position can be accurately corrected.

  Further, by providing the gap portion 31a between the support roller 52 and the belt abutting portion 41a, the load received when the belt end portion 3a abuts against the flat surface portion 41b is reduced, and the belt end portion 3a or its vicinity Q is cracked. It is possible to prevent the belt from being broken due to cracks and cracks.

  In the present embodiment, the gap portion 31b may be provided between the belt end support portion 7 and the belt abutting portion 41a. In this case, even if the belt end portion support portion 7 moves outward in the axial direction due to the movement in the axial direction generated by the backlash of the support roller 52, the belt end portion support portion 7 is located between the belt abutting portion 41a. Since there is the gap portion 31b, it is possible to prevent a force from being applied to the belt abutting portion 41a. In addition, any method other than providing the gap portion 31b may be used as long as the force is not applied to the shaft displacement portion 41 by the movement of the support roller 52 in the axial direction caused by the play. Also good.

  Further, although the support roller 52 is provided with the belt control device, the belt control device may be provided at the end of any two or more of the drive roller 51 and the support rollers 52, 53, and 54.

  In the present embodiment, a belt control device may be provided at both ends of one or more of the drive roller 51 and the support rollers 52, 53, and 54.

  Further, in the present embodiment, the shaft displacement portion 41 has an inclined surface 41d that is a flat surface that is inclined outwardly in the axial direction of the roller with respect to a surface parallel to the surface of the belt in the axial direction of the roller. 52, the inclined surface 41d is a flat surface that is inclined outwardly in the roller axial direction with respect to a surface parallel to the surface of the belt outward in the roller axial direction. It may be provided below the shaft of the support roller 52.

  Further, in the present embodiment, the shaft displacement portion 41 is formed by the frictional force generated between the belt end portion 3a and the flat portion 41b when the belt travels in the running direction with the belt end portion 3a being in contact with the flat portion 41b. The abutting portion 41a rotates according to the travel of the belt 3. As a result, the load received by the belt end 3a due to the frictional force can be reduced, and damage to the belt 3 and wear of the flat surface portion 41b can be prevented.

  Further, the belt abutting portion 41a may be provided as the shaft displacement portion 41 integrally with the shaft inclined portion 41c.

DESCRIPTION OF SYMBOLS 1 Photoconductor 3 Intermediate transfer belt 6 Roller shaft 7 Belt end support part 8 Charging device 9 Exposure device 10 Developing 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 Discharge roller pair 20 Belt cleaning device 21 Cleaning blade 31a Clearance portion 31b Clearance portion 40 Belt position correction portion 41 Axial displacement portion 41a Belt abutting portion 41b Flat portion 41c Shaft inclined portion 41d Inclined surface 42 Shaft guide portion 43 Roller shaft Support part 45 Roller shaft support spring 46 Fixed part 51 Drive roller 52 Support roller 53 Support roller 54 Support roller

JP 2009-288426 A

Claims (6)

A belt control device that controls movement of at least one of the plurality of rollers in the axial direction of a belt that is stretched between the plurality of rollers and travels with rotation of the plurality of rollers;
An inclined surface that is inclined with respect to a plane parallel to the surface of the belt, and the belt moves in the axial direction of the roller so as to contact the inclined surface and the axial displacement portion that moves in the axial direction. A shaft guide portion fixedly installed on
A gap larger than the axial play on the roller installation is formed between the roller and the shaft displacement portion,
The inclined surface is inclined obliquely upward so as to become lower toward the outer side in the axial direction, and the axial displacement portion is pushed to the axial guide portion by being pushed by the belt moving outward in the axial direction. Inclined so as to fall while touching on an inclined surface ,
Means for providing a force for displacing the shaft displacing portion upward to maintain a contact state between the inclined surface and the guide portion . The belt control device according to claim 1,
The shaft displacement portion has a belt abutting portion against which a belt moved in the axial direction abuts,
The belt control device according to claim 1, wherein the gap portion is between the roller and the belt abutting portion. The belt control device according to claim 2,
The belt controller according to claim 1, wherein the belt abutting portion rotates in accordance with the travel of the abutted belt. The belt control device according to any one of claims 1 to 3,
A belt control device comprising the shaft displacement portion and the shaft guide portion at both ends of the one roller. A roller unit used in a belt control device that controls movement of at least one of the plurality of rollers in the axial direction of a belt that is stretched around the plurality of rollers and travels with rotation of the plurality of rollers. ,
An inclined surface that is inclined with respect to a plane parallel to the surface of the belt, and the belt moves in the axial direction of the roller so as to contact the inclined surface and the axial displacement portion that moves in the axial direction A shaft guide portion fixedly installed on
A gap larger than the axial play on the roller installation is formed between the roller and the shaft displacement portion,
The shaft displacement portion is inclined to be lowered while being in contact with the shaft guide portion at the inclined surface by being pushed by the belt moving outward in the axial direction ,
A roller unit characterized in that means for applying a force for displacing the shaft displacement portion is provided to maintain the contact state between the inclined surface and the guide portion .   An image forming apparatus comprising the belt control device according to claim 1 or the roller unit according to claim 5.

Images