JP6570590B2 - Belt conveying apparatus and image forming apparatus - Google Patents

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a belt conveyance device that rotates and moves an endless belt while being stretched by a plurality of stretching members, and an image forming apparatus such as a printer or a copier that uses an electrophotographic system including the belt conveyance device. It is.

  2. Description of the Related Art Conventionally, some image forming apparatuses such as printers and copiers using an electrophotographic system use a belt conveyance device that rotates and moves an endless belt while being stretched by a plurality of stretching members. In such a belt conveyance device, there is a problem that when the belt is rotationally moved, the belt approaches one end side in the belt width direction (axial direction of the stretching roller) that is a direction orthogonal to the belt movement direction. Are known.

  In order to solve this problem, for example, Patent Document 1 discloses a configuration in which the deviation of the belt is adjusted using a force (rotational torque) in the moving direction of the belt. Specifically, in Patent Document 1, the initial position (initial phase) is determined by the biasing spring, and the contact member that rotates in the moving direction of the belt by contacting the moving belt and the contact member rotate integrally. It has a cam to play. And in patent document 1, when a belt approaches the belt width direction one end side, a belt and a contact member will contact and a rotational torque will be transmitted from a belt to a contact member. When the contact member rotates by a certain angle or more, the cam displaces the position of the driven roller shaft end portion in a direction perpendicular to the axial direction. Thus, in Patent Document 1, the driven roller is tilted with respect to the driving roller to adjust the deviation of the belt.

Japanese Patent Laid-Open No. 11-116089

  However, Patent Document 1 includes a biasing spring that biases the shaft end of the driven roller in the vertical direction, and returns the position of the shaft end of the driven roller to the initial position. Specifically, the position of the shaft end portion of the driven roller is adjusted by pulling the driven roller with an urging spring in order to cancel the inclination of the driven roller end portion after adjusting the belt deviation.

  That is, in Patent Document 1, in order to rotate the contact member and displace the position of the driven roller shaft end in order to adjust the deviation of the belt, a rotational torque exceeding the return force by the biasing spring is applied from the belt to the contact member. Need to give. Therefore, when the belt rotates the contact member, there is a concern that a load is applied to the end portion of the belt and damage occurs. Further, when the position of the driven roller shaft end is displaced, a force greater than the spring force of the urging spring is generated in the contact region between the contact member and the belt, and the load on the belt is large.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a belt conveyance device capable of adjusting the deviation of the belt with a small load on the belt, and an image forming apparatus including the belt conveyance device.

In order to solve the above-described problems, the present invention provides an endless belt that rotates and moves, a first tension member that stretches the belt, a second tension member that stretches the belt, And when the belt approaches one end side in the belt width direction perpendicular to the moving direction of the belt, the first tension member is inclined with respect to the second tension member to In the belt conveyance device for regulating the shift, the position of the end portion on the one end side of the first stretching member is regulated on the one end side of the first stretching member in the belt width direction. A first adjustment member rotatable with respect to the first tension member; and provided on the other end side of the first tension member in the belt width direction. In order to regulate the position of the end on the other end side, And a second adjustment member that is rotatable, and interlocking means for interlocking the rotation of the second adjustment member with the rotation of the first adjustment member, wherein the belt is in the belt width direction. When approaching one end side, the first adjustment member receives a force from the belt and rotates in the rotational movement direction of the belt, and the second adjustment member rotates the first adjustment member by the interlocking means. By rotating in the direction opposite to the direction, the first tension member is inclined with respect to the second tension member, and the interlocking means moves the first tension member to the second tension member. The posture of the first adjustment member and the second adjustment member with respect to the first tension member is maintained in a state where the belt is restricted from being tilted with respect to the first tension member.

  According to the present invention, it is possible to adjust the deviation of the belt while the load on the belt is small.

Schematic of an image forming apparatus provided with a belt conveying device of the present invention 1 is a perspective view of an intermediate transfer belt unit according to Embodiment 1. FIG. 1 is a perspective view of an end portion side of a tension roller 7 that applies tension to the intermediate transfer belt 5 according to the first embodiment. FIG. 3 is an exploded perspective view illustrating components of the belt-side adjustment mechanism according to the first embodiment. Sectional view of the belt offset adjusting mechanism as seen from the direction of arrow B in FIG. The partial side view of the belt shift adjustment mechanism of Embodiment 1 The figure explaining operation | movement of the adjustment member of the belt deviation adjustment mechanism of Embodiment 1. The figure explaining the rotation angle of the adjustment member of Embodiment 1, and the displacement amount of a bearing The figure explaining operation | movement of the belt deviation adjustment mechanism of Embodiment 1. The figure explaining the force which acts on the adjustment member which is not connected to the link member The figure explaining the relationship between the rocking | fluctuation shaft of a connection member, and an adjustment member The figure explaining the position of the fulcrum of a bearing support member The figure explaining the experimental result which confirmed the effect of the belt deviation adjustment mechanism of Embodiment 1. Partial side view of the belt offset adjusting mechanism of the second embodiment The figure explaining the rotation angle of the adjustment member of Embodiment 2, and the displacement amount of a bearing Schematic sectional view of the belt offset adjusting mechanism of the second embodiment Sectional drawing which shows another embodiment of the belt shift adjustment mechanism of Embodiment 2. Sectional drawing of the intermediate transfer belt unit of Embodiment 3 The figure explaining the shape of adjustment member 21L, R of Embodiment 3. The figure explaining the relationship between the adjustment member 21, the bearing guide part 17, and the rubbing surface 22 of Embodiment 3. Schematic cross-sectional view of the belt offset adjusting mechanism of the fourth embodiment Schematic illustrating an image forming apparatus according to another embodiment

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in the following embodiments should be appropriately changed according to the configuration of the apparatus to which the present invention is applied and various conditions. Therefore, unless specifically stated otherwise, the scope of the present invention is not intended to be limited thereto.

(Embodiment 1)
(Overall configuration of image forming apparatus)
An embodiment of an image forming apparatus provided with a belt conveyance device according to the present invention will be described. FIG. 1 is a sectional view of an intermediate transfer type electrophotographic color image forming apparatus. An intermediate transfer belt unit 16 is provided as a belt conveyance device provided with a belt deviation adjusting mechanism according to the present invention.

(Overall configuration of image forming apparatus)
FIG. 1 is a schematic diagram illustrating an example of a color image forming apparatus. The configuration of the image forming apparatus according to the present embodiment will be described with reference to FIG. The image forming apparatus 10 forms an image on a transfer material P such as a recording sheet or an OHP sheet by an electrophotographic method in accordance with a signal sent from an external device such as a personal computer that is communicably connected to the image forming apparatus 10. can do.

  In the image forming apparatus 10, a plurality of image forming units a, b, c, and d that form toner images of yellow, magenta, cyan, and black are arranged linearly in a substantially horizontal direction here. . Further, a belt conveyance device is disposed so as to face each of the image forming units a, b, c, and d. The belt conveyance device of the present embodiment is a transfer unit in which a belt and other members are unitized.

  The transfer unit of the present embodiment is stretched by stretch members (drive roller 6, tension roller 7, driven roller 8), and an endless belt (intermediate transfer belt) 5 as an intermediate transfer member is attached to each image forming unit a. , B, c, and d, an intermediate transfer belt unit 16 that rotates and moves. Each of the image forming units a, b, c, and d has the same configuration and operation except that the color of the toner image to be formed is different. Therefore, the configuration of the image forming unit a will be described as a representative.

  In the image forming unit a, a toner image is formed by a known electrophotographic image forming process. The image forming unit a is provided with a cylindrical electrophotographic photosensitive member, that is, a photosensitive drum 1a, as an image carrier so as to be rotatable in the direction of an arrow in the figure. In the image forming operation, first, the surface of the rotating photosensitive drum 1a is charged by the charging roller 2a serving as charging means. Next, the laser scanner 3 as an exposure unit emits light in accordance with a signal sent from the computer, and an electrostatic latent image is formed on the photosensitive drum 1a by performing scanning exposure on the charged photosensitive drum 1a. The electrostatic latent image formed on the photosensitive drum 1a is visualized as a toner image when the developing roller 4a as a developing unit supplies toner as a developer. The toner image visualized on the photosensitive drum 1a is statically transferred onto the belt 1 by the action of a primary transfer roller 9a which is a primary transfer unit disposed opposite to the photosensitive drum 1a via the belt 1 in the primary transfer portion T1. It is transferred electronically. The primary transfer residual toner remaining on the surface of the photosensitive drum 1 is cleaned and removed by the cleaning device 11a and then subjected to an image forming process below charging.

  Through the above process, the toner images formed on the photosensitive drums 1a of the image forming units a, b, c, and d with the movement and timing of the belt 1 are sequentially superimposed and transferred onto the belt 1. A color toner image is formed.

  On the other hand, the transfer material P sent out from the transfer material accommodating portion by the feeding means 9a or the like takes a timing to contact the secondary transfer roller 12 as the secondary transfer means and the belt 5 (secondary transfer portion). It is conveyed to T2. Thus, the toner image on the belt 1 is electrostatically transferred to the transfer material P by the action of the secondary transfer roller 12 in the secondary transfer portion T2.

  Next, the transfer material P is separated from the belt 1 and conveyed to the fixing unit 14 where the toner image on the transfer material P is pressurized and heated to be firmly fixed on the transfer material P. Thereafter, the transfer material P is conveyed and discharged onto a discharge tray. Further, the secondary transfer residual toner remaining on the surface of the intermediate transfer belt 5 is cleaned and removed by the transfer belt cleaning means 15.

  The density of the toner image primarily transferred onto the intermediate transfer belt 5 can be detected by a sensor unit 24 provided at a position facing the tension roller 7 via the intermediate transfer belt 5.

  In the image forming apparatus 10 of the present embodiment, the intermediate transfer belt unit 16 that is a transfer unit is also detachable from the image forming apparatus 10. That is, the belt conveying device is configured to be detachable from the image forming apparatus. Further, the photosensitive drums 1a, b, c, and d and the developing rollers 4a, b, c, and d of each image forming unit 110 are integrated into a cartridge by a frame and can be attached to and detached from the image forming apparatus 10. A cartridge may be used.

(Description of schematic configuration of intermediate transfer belt unit)
Next, the configuration of the intermediate transfer belt unit 16 and the belt deviation adjusting mechanism will be described with reference to FIGS. The intermediate transfer belt unit 16 includes an intermediate transfer belt 5, a plurality of stretching members (a driving roller 6, a tension roller 7, and a driven roller 8) that stretch the intermediate transfer belt 5, and a frame member that supports the plurality of stretching members. 17R and L are units. Further, the intermediate transfer belt unit 16 includes primary transfer rollers 9a, b, c, and d. The intermediate transfer belt unit 16 is configured to be positioned with respect to the main body frame member 60 of the image forming apparatus 10.

  FIG. 2 is a perspective view of the intermediate transfer belt unit 16. For explanation of the internal mechanism, the intermediate transfer belt 5 and the sensor unit 24 are not shown.

  As shown in FIG. 2, the driving roller 6 and the driven roller 8 are positioned with respect to the frame members 17L and 17R via bearings. The rotation shafts of the driving roller 6 and the driven roller 8 are supported by a bearing so as to be rotatable. The tension roller 7 is supported by adjustment members 21L and 21R described later so as to be movable with respect to the frame members 17R and 17L. The driving roller 6 is rotationally driven by a driving unit (not shown) and conveys the intermediate transfer belt 5. The tension roller 7 and the driven roller 8 are driven in contact with the intermediate transfer belt 5.

  A configuration for applying tension to the intermediate transfer belt 5 will be described with reference to FIGS. FIG. 3 is a perspective view of the end side of the tension roller 7 that applies tension to the intermediate transfer belt 5. FIG. 4 is an exploded perspective view illustrating components of the belt deviation adjusting mechanism. Further, FIG. 5 is a cross-sectional view of the belt-side adjustment mechanism viewed from the direction of arrow B in FIG.

  As shown in FIG. 3, the tension roller bearing 18L (18R) is slidably engaged with the tension roller bearing holder 19L (19R) in the direction of arrow A. The tension roller bearing 18L (18R) has a tension roller rotating shaft 50 that applies tension to the intermediate transfer belt 5 by an urging means (tension spring 20) provided between the tension roller bearing holder 19L (19R). The tension roller 7 is urged through.

  As shown in FIGS. 4 and 5, the tension roller 7 includes a tension roller sleeve 7a, a tension roller flange 7b, and a tension roller rotating shaft 50, and is configured to rotate integrally. Both ends of the rotary shaft 50 of the tension roller are pivotally supported by tension roller bearings 18L and 18R that are bearing support members.

  Next, a belt shift adjustment mechanism that functions when the belt approaches one end side in the belt width direction orthogonal to the moving direction will be described. The belt shift adjustment mechanism of the present embodiment includes at least a tension roller 7 as a shift adjustment stretch member, a first adjustment member, and adjustment members 21L and 21R as second adjustment members. Here, since the configurations of the adjustment members 21L and 21R are the same, the adjustment member that comes into contact with the belt when the intermediate transfer belt 5 approaches is defined as a first adjustment member, and the other is defined as a second adjustment member. The belt shift adjustment mechanism adjusts the shift of the belt by tilting one of the plurality of tension members with respect to the other tension member. , Is defined as an offset adjustment tension member. As described above, in this embodiment, the offset adjusting tension member is the tension roller 7.

  The adjustment members 21L and 21R are configured to be movable by receiving a force from the belt, and are provided on both ends of the tension roller 7 as shown in FIG. Specifically, the adjusting members 21L and 21R have a cam shape, and rotate in the same direction as the moving direction of the belt by coming into contact with the belt when the belt approaches the belt width direction. The cam curved surfaces 21b of the adjusting members 21L and 21R are in contact with the rubbing surface 22 formed on the main body frame member 60 (see FIG. 1). The adjustment members 21L and 21R are supported by the tension roller bearings 18L and 18R, and are rotatably engaged with the tension roller bearings 18L and 18R. Therefore, the rotation shafts of the adjustment members 21L and 21R are coaxial with the rotation shaft of the tension roller 7. Here, the rubbing surface 22 is a flat member facing the tension roller 7 as shown in FIG. 5 below the tension roller 7 shown in FIG. The rubbing surface 22 may be formed on the main body frame member 60 or may be formed as a part of the intermediate transfer belt unit 16.

  As shown in FIG. 5, the positions of the tension roller bearings 18L and 18R, the tension roller rotating shaft 50, and the tension roller 7 in the Z direction (hereinafter, the Z direction is referred to as the height direction) are the rubbing surface 22 and the adjusting member. 21L and 21R.

  FIG. 6 is a partial side view of the belt side adjusting mechanism on the L side. The relationship between the members on the R side is the same as in FIG. As shown in FIG. 6, the tension roller bearing holder 19L is held so as to be swingable by a predetermined angle about the bearing holder fulcrum 19a with respect to the frame member 17L. That is, the tension roller bearing holder 19L is configured to be able to follow the height of the tension roller 7 defined by the adjustment member 21L while holding the tension spring 20.

  FIG. 7 is a view showing the relationship between the operation of the adjusting member 21L and the operation of the tension roller 7. As described above, the cam curved surface 21b formed on a part of the adjustment member 21L is in contact with the rubbing surface 22 that is a fixed surface. Further, the cam shape is such that the height of the tension roller bearing 18L is continuously changed by the rotational phase of the adjusting member 21L. Specifically, in FIG. 7B, when the adjustment member 21L rotates in the conveyance direction of the intermediate transfer belt 5 (C direction), the tension roller bearing 18L operates to be lowered (state of FIG. 7C). . In FIG. 7B, when the adjustment member 21L rotates in the direction opposite to the belt moving direction (−C direction), the tension roller bearing 18L operates to be lifted (state shown in FIG. 7A).

  FIG. 8 is a diagram for explaining the rotation angle of the adjusting member and the amount of displacement of the bearing. The relationship between the rotation angles of the adjusting members 21L and 21R and the displacement amounts of the tension roller bearings 18L and 18R is approximately as shown in FIG. The tension roller rotating shaft 50 and the tension roller 7 supported by the tension roller bearings 18L and 18R also follow the tension roller bearings 18L and 18R and are displaced.

  When one of the adjusting members 21L and 21R is moved by receiving a force from the intermediate transfer belt 5 when the intermediate transfer belt 5 moves in the belt width direction, the other moves in the opposite direction in conjunction with the movement. To do.

  In the present embodiment, the adjusting members 21L and 21R are connected by a connecting member (link member 23) provided as interlocking means, as shown in FIG. The link member fulcrum shaft 23a of the link member 23 is swingably supported by the frame member 17C in a substantially central region in the width direction of the intermediate transfer belt 5. The link member 23 includes adjustment member engagement portions 23b-L and 23b-R. The adjustment member engagement portions 23b-L and 23b-R are respectively connected to the link member engagement portions 21d of the adjustment members 21L and 21R. Is engaged. The link member engaging portions 21d of the adjustment members 21L and 21R are provided on the upstream side of the rotation shaft of the tension roller. When one of the adjusting members 21L and 21R is rotated in a certain direction (C direction) by the connecting member, the other is configured to rotate approximately the same angle in the reverse direction (−C direction) via the link member 23. .

(Outline explanation of belt misalignment correction operation)
FIG. 9 is a diagram for explaining the operation of the belt deviation adjusting mechanism. The misalignment adjustment operation of the belt conveyance device of the present embodiment will be described with reference to FIGS.

  As shown in FIG. 9A, the intermediate transfer belt 5 is conveyed in the K direction by the drive roller 6. Here, the correction operation when the intermediate transfer belt 5 is shifted in the F direction will be described.

  When the intermediate transfer belt 5 moves in the direction of arrow F, the belt end 5a comes into contact with the belt rubbing surface 21c of the adjusting member 21R, and the shift of the intermediate transfer belt 5 in the F direction is adjusted (FIG. 5B). )). By regulating the deviation of the belt, a contact pressure is generated between the belt end 5a and the belt rubbing surface 21c. This contact pressure is called an offset force. If the belt deviation adjusting mechanism is not provided, if this deviation force increases, the load on the belt end increases, which may lead to damage to the intermediate transfer belt 5.

  When the belt end 5a comes into contact with the belt rubbing surface 21c of the adjustment member 21R, the belt end 5a causes the belt end 5a to move the adjustment member 21R as shown in FIG. The intermediate transfer belt 5 is rotated in the direction of rotation (arrow C direction). With the rotation of the adjusting member 21R in the C direction, the end of the tension roller 7 on the side (R side) where the intermediate transfer belt 5 is moved down. At the same time, the adjusting member 21R swings the linked link member 23 about the link member fulcrum 23a, and the link member 23 moves the adjusting member 21L on the opposite side in the direction opposite to the belt moving direction (-C direction). Rotate to Along with the rotation of the adjusting member 21L, the end of the tension roller 7 on the opposite side (L side) to the side where the intermediate transfer belt 5 is offset moves upward.

  With the above operation, the tension roller 7 is inclined with respect to the drive roller 5. Both end portions of the tension roller 7 are displaced by approximately the same amount in the opposite directions by the link member 23, that is, the tension roller 7 is inclined symmetrically with respect to the link member fulcrum 23a in the belt width direction.

  The belt conveyance device of the present embodiment tries to move the intermediate transfer belt 7 in the direction opposite to the initial shift direction (F direction) by the inclination of the tension roller 7, so that the shift of the intermediate transfer belt 7 is adjusted, Reduce the shifting force. When the shifting force of the intermediate transfer belt 5 becomes sufficiently small, the belt end 5a loses the force for rotating the adjusting member 21R, and the adjusting member 21R stops rotating. At the same time as the adjusting member 21R stops rotating, the adjusting member 21L also stops rotating. The adjustment member 21R and the adjustment member 21L maintain their positions (phases) after stopping the rotation.

  As described above, the belt shift adjustment mechanism of the present embodiment is configured such that when the belt shift occurs, the adjustment members 21L and 21R move in the opposite directions to tilt the tension roller 7, This is a configuration that is easier to tilt than a configuration that tilts only with one adjusting member.

  FIG. 10 shows the force acting on the adjusting member 21 </ b> R that is not connected to the link member 23. A point I is a contact point between the adjusting member 21R and the rubbing surface 22, and Lw indicates a distance between the shafts 21a and I in the horizontal direction. Here, the shaft 21a is the rotation center of the adjustment member 21R.

  The adjusting member 21R is in contact with the rubbing surface 22 at the point I, and the weight W (R) of the tension roller 7 acts on the position of the shaft 21a shifted by Lw. Therefore, a force rotating in the J direction acts on the adjustment member 21R. The same applies to the adjustment member 21L on the opposite side. That is, the adjustment members 21R and 21L rotate in the J direction with each other in a freely rotatable state, and the tension roller bearings 18R and 18L rotate together as shown in FIG. Therefore, in order to rotate the position of the tension roller bearings 18R and 18L in the direction opposite to the J direction, a biasing force of a biasing member such as a spring that pulls the tension roller bearings 18R and 18L is required.

  However, in this embodiment, it is not necessary to provide a biasing means such as a tension spring. As shown in FIG. 11, adjustment members 21L and 21R are provided at substantially symmetrical positions around the swing shaft 23a. The weights of the tension roller 7 are applied to the adjusting members 21L and 21R substantially evenly, and the rotational moments thereof are also substantially uniform. This indicates that the rotational moment applied to the adjustment members 21L and 21R on both sides is balanced via the link member 23 in a state where no offset force is generated in the intermediate transfer belt 5, and the stationary state can be maintained. That is, in the present embodiment, the inclination of the tension roller 7 can be maintained independently without depending on the force received from the intermediate transfer belt 7 or the force of the urging means such as a tension spring.

  Further, the link member 23 allows the rotation amount of one adjustment member and the reverse rotation amount of the other adjustment member to be substantially equal, and the rotation moments of the adjustment members 21L and 21R can be kept balanced. It is.

  Moreover, in this embodiment, since it is not necessary to rotate adjustment member 21L, 21R against the urging | biasing force of a tension spring, it is possible to rotate adjustment member 21L, 21R with a small load.

(Detailed description regarding the position of the bearing holder fulcrum 19a)
In the belt deviation adjusting mechanism of the present embodiment, the belt deviation adjusting operation is started when the intermediate transfer belt 5 rotates the adjustment members 21L and 21R. Therefore, in order to minimize the load on the intermediate transfer belt 5, it is preferable to reduce the rotational load on the adjusting members 21L and 21R.

  The cam curved surfaces 21b of the adjusting members 21L and 21R slide with the rubbing surface 22. That is, the rotational load on the adjusting members 21L and 21R can be reduced by reducing the frictional force between the cam curved surface 21b and the rubbing surface 22. The frictional force between the cam curved surface 21b and the rubbing surface 22 is mainly governed by the normal force acting by the weight of the tension roller 7 and the tension of the intermediate transfer belt 5, and the friction coefficient between the cam curved surface 21b and the rubbing surface 22. The Therefore, it is preferable to reduce these.

  In the present embodiment, the position of the tension roller bearing holder 19 is adjusted in order to reduce the rotational load on the adjusting members 21L and 21R. FIG. 12 is a cross-sectional view illustrating the position of the tension roller bearing holder 19. The tension roller bearing holder 19 holds the tension spring 20, the tension roller bearing 18, and the tension roller 7. These are configured so that they can rotate integrally around the bearing holder fulcrum 19a according to the position of the tension roller 7. The tension spring 20 can always press the substantial center of the tension roller 7 regardless of the position of the tension roller 7. As a result, the tension spring 20 is configured not to interfere with the belt shift adjustment operation.

  Considering the force required to tilt the tension roller 7, the roller end can be tilted with a smaller force than the roller center. In this embodiment, since the adjustment member 21 is disposed at both ends of the tension roller 7, the adjustment member 21 can tilt the tension roller 7 with a small force.

  A resultant force Tt of the tensions T 1 and T 2 of the intermediate transfer belt 5 acts on the tension roller 7 and is supported by a tension roller bearing holder 19.

  As shown in FIG. 12A, when the bearing holder fulcrum 19a is arranged on the vector of the resultant force Tt, no rotational moment acts on the tension roller bearing holder 19. On the other hand, when the bearing holder fulcrum 19a is arranged above the vector direction of the resultant force Tt as shown in FIG. 12B, a rotational moment acts in the E direction around the bearing holder fulcrum 19a. Here, the magnitude of the rotational moment is determined according to the distance between the vector of the resultant force Tt and the bearing holder fulcrum 19a. Conversely, when the bearing holder fulcrum 19a is disposed below the vector direction of the resultant force Tt as shown in FIG. 12C, a rotational moment acts in the −E direction due to the tension T.

  This moment acts on the vertical drag between the cam curved surface 21 b and the rubbing surface 22. That is, by changing the position of the bearing holder fulcrum 19a, the contact pressure between the cam curved surface 21b of the adjusting members 21L and 21R and the rubbing surface 22 can be set appropriately.

  The vector direction of the resultant tension force Tt substantially coincides with the bisector 80 in the stretching direction of the intermediate transfer belt 5 when the rotational load of the tension roller 7 is small.

  In this embodiment, the position of the bearing holder fulcrum 19a is disposed below the bisector 80 of the winding angle of the intermediate transfer belt 5. That is, they are arranged below the vector direction of the resultant tension force Tt. A moment in the −E direction acts on the tension roller bearing holder 19. As a result, the tension of the intermediate transfer belt 5 can cancel the weight of the tension roller 7. Thereby, the frictional force between the cam curved surface 21b and the rubbing surface 22 is reduced, and the rotational load on the adjusting members 21L and 21R is reduced. As a result, the belt shift correction operation can be performed without imposing a large load on the intermediate transfer belt 5.

(Experimental result)
The result of actually performing the belt deviation adjusting operation in the above configuration will be shown.

  Fig.13 (a) is a figure for demonstrating the amount of twist. As shown in FIG. 13A, the belt is tilted by tilting the tension roller 7 only one side from the dotted line position. The height P of the roller end is defined as the twist amount.

  The shift adjustment operation was confirmed by measuring the shift force of the intermediate transfer belt 5. The shifting force was measured by a load cell (model: LMA-A-20N M81, Kyowa Dengyo), which is the force by which the intermediate transfer belt 5 pushes the adjustment member 21 when the intermediate transfer belt 5 approaches.

  FIG. 13B shows a result of the intermediate transfer unit 21 performing the belt shift adjustment operation. The horizontal axis shows time, and the vertical axis shows the shifting force. On the horizontal axis, the time when the intermediate transfer belt 5 and the adjusting members 21L and 21R start to contact each other is set to zero. It is the result of measuring the deviation force under four conditions, when the belt deviation adjustment operation is performed and when it is not performed with respect to two conditions of a twist amount of 1.2 mm and a twist amount of 2.6 mm. The thin broken line (A) is corrected with a twist amount of 1.2 mm, the thin solid line (B) is corrected with a twist amount of 1.2 mm, and the thick broken line (C) is corrected with a twist amount of 2.6 mm, a thick solid line (D) shows the offset force with correction with a twist amount of 2.6 mm.

  When there was no shift adjusting mechanism, the shift force (N) gradually increased and converged to a shift force of about 6 N when the twist amount was 1.2 mm. When the twist amount was 2.6 mm, the twisting force converged to about 10 N. On the other hand, in the intermediate transfer unit provided with the belt deviation adjusting mechanism of the present embodiment, it is possible to converge to 1 N or less in both cases where the twist amount is 1.2 mm and 2.6 mm. The shifting force could be converged to 1N or less.

  Therefore, the belt shift adjustment mechanism of the present embodiment can adjust the belt shift in a state where the load generated on the belt is small, and even when the intermediate transfer belt 5 is continuously conveyed, the belt is hardly damaged. There is an effect to.

(Embodiment 2)
In the first exemplary embodiment, the configuration in which the adjustment members 21L and 21L are driven to rotate by receiving a shifting force from the belt end 5a of the intermediate transfer belt 5 has been described. On the other hand, in the present embodiment, on the inner peripheral surface of the intermediate transfer belt 5, the adjustment members 21L and 21R are rotated by receiving the shifting force from the position regulating ribs 35L and R provided at the longitudinal ends. explain. Since other configurations are the same as those of the image forming apparatus according to the first embodiment, the same portions are denoted by the same reference numerals and described.

  The configuration of the present embodiment will be briefly described with reference to FIGS. FIG. 14 is a schematic cross-sectional view for explaining the belt deviation adjusting mechanism of the present embodiment. FIG. 14 is a schematic cross-sectional view illustrating an adjustment member 21L in the second embodiment. Since the configuration of the adjustment member 21R is the same, the description thereof is omitted. As shown in FIG. 14, the adjustment member 21 </ b> L of the present embodiment is opposite to the configuration of the first embodiment in the shape of the cam surface and the position where it is engaged with the link member 23. The link member engaging portions 21d of the adjustment members 21L and 21R are provided on the downstream side of the rotation shaft of the tension roller.

  Here, when the adjusting member 21L rotates in the belt moving direction (C direction), the tension roller bearing 18L is lifted upward, and when the adjusting member 21L rotates in the direction opposite to the belt moving direction (−C direction), the tension roller bearing 18L is lowered downward. Acts as follows. FIG. 15 shows the relationship between the rotation angles of the adjusting members 21L and 21L and the displacement amount of the tension roller bearing 18L.

  FIG. 16 is a schematic cross-sectional view illustrating the belt shift adjusting mechanism of the present embodiment. Position restricting ribs 35L, R provided at both ends of the belt 5 can contact the adjusting members 21L, 21R. As shown in FIG. 14, the intermediate transfer belt 5 is conveyed in the arrow K direction. When the intermediate transfer belt 5 is moved in the direction of arrow F in FIG. 15 (for example, one end side), the position regulating rib 35L (the other end side rib) comes into contact with the adjusting member 21L and rotationally drives the adjusting member 21L. When the adjustment member 21L is rotated in the C direction (the same direction as the K direction) by the belt offset force, the cam curved surface 21b of the adjustment member 21L is in contact with the sliding surface 22 and lifts the tension roller bearing 18 upward.

  When the adjustment member 21L rotates, the link member 23 rotates the opposite adjustment member 21R in the opposite direction (−C direction) to the adjustment member 21L as in the first embodiment. As a result, the tension roller bearing 18R is lowered downward (−Z direction). By this operation, the tension roller 7 is tilted, and the deviation of the belt can be corrected.

  Here, attention is paid to the movement of the tension roller 7 in the longitudinal direction (Y direction). As described above, the tension roller 7 receives the reaction force of the offset force of the intermediate transfer belt 5 and applies a force in the direction of arrow N. Accordingly, the adjustment member 21L can be sandwiched and driven by the position regulating rib 35L and the tension roller 7. That is, the adjustment member 21L can obtain a driving force from the position regulating rib 35L and the tension roller 7. Further, since the tension roller 7 exerts a force on the adjustment member 21L side, the tension roller 7 does not hinder the operation of the adjustment member 21R, and does not hinder the belt deviation correction operation.

  As described above, the deviation of the belt can be adjusted by the position regulating ribs 35L and 35R. By driving the adjustment members 21L, R via the position regulating ribs 35L, R, it is not necessary to bring the belt end portion 5a into contact with the adjustment members 21L, R, and the load on the belt 5 can be further reduced.

  FIG. 17 is a diagram illustrating another drive transmission means to the adjustment members 21L and 21R. In this configuration, rib pulleys 42L, R and clutch plates 43L, R are provided. The rib pulleys 42L, R are rotatably engaged with the adjustment members 21L, R, and are arranged coaxially with the tension roller 7. On the other hand, the clutch plates 43L, R are coupled to the adjustment members 21L, R and are configured to move at a constant speed.

  As shown in FIG. 17, when the belt 5 is deviated and the belt 5 is moved in the F direction, the position regulating rib 35L moves in the F direction. The position regulating rib 35L and the tension roller 7 sandwich the rib pulley 42L and the clutch plate 43L, and rotate the adjustment member 21L. The adjustment member 21L rotates at the same speed as the clutch plate 43, so that the tension roller 7 is tilted to correct the belt shift.

  Here, the rib pulley 42L is configured to be in contact with the clutch plate 43L at a portion having a small radius from the rotation center, and is configured to be in contact with the position regulating rib 35L at a portion having a large radius. Therefore, when contacting the position restricting rib 35L, the rib pulley 42L rotates at substantially the same speed as the position restricting rib 35L. Therefore, it is possible to reduce the wear of the position regulating rib 35L.

(Embodiment 3)
In the first embodiment, the configuration has been described in which the tension roller 7 that applies tension to the intermediate transfer belt 5 with the spring 20 is adjusted by tilting the tension roller 7 with the adjustment members 21L and 21R. On the other hand, in the present embodiment, a description will be given of a configuration in which the driven roller 8 driven and rotated by the belt 5 is tilted with respect to the driving roller 6 by the adjusting members 21L and 21R to restrict the belt shift. Since other configurations are the same as those of the image forming apparatus according to the first embodiment, the same portions are denoted by the same reference numerals and described.

  As shown in FIG. 18, the present invention can also be applied to a configuration in which adjustment members 21L and 21R are provided at both ends of the driven roller 8. First, the operation of the shift correction mechanism will be described. Similarly to the first embodiment, when the belt 5 approaches one end side and contacts the adjustment member 21L, the adjustment member 21L rotates by receiving a rotational force from the belt 5.

  The cam curved surface 21b is also rotated by the rotation of the adjusting member 21L, the contact state between the cam curved surface 21b and the rubbing surface 22 is changed, and the end of the driven roller 8 is displaced in the −X direction. When the adjusting member 21L rotates, the adjusting member 21R connected by the link member 23 rotates in the reverse direction, and the end of the driven roller 8 supported by the adjusting member 21R is displaced in the + X direction. In this way, the displacement of the belt 5 can be regulated by displacing the driven roller 8 in the X direction so as to return the displacement of the belt 5.

  Next, a detailed configuration of the shift adjustment mechanism will be described. Since the configuration of each member is the same on the L side and the R side, L and R will be described below without distinction. FIG. 19 is a schematic diagram illustrating the shapes of the adjusting members 21L and 21R of the present embodiment. FIG. 20 is a schematic diagram illustrating the relationship among the adjustment member 21, the bearing guide portion 17, and the rubbing surface 22 according to the present embodiment.

  In the present embodiment, both ends of the driven roller 8 are supported by the adjustment member 21 and the driven roller bearing 41. By fitting the cam curved surface 21 b to the rubbing surface 22, the adjustment member 21 is configured to restrict the position of the end portion of the driven roller 8 in the X direction. That is, the adjustment member 21 uniquely determines the position of the end portion of the driven roller 8 in the X direction.

  Here, the adjustment member 21 does not regulate the position of the end portion of the driven roller 8 in the Z direction. The adjusting member 21 supports both ends of the driven roller 8, and each adjusting member 21 is coupled by a link member 23 as in the first embodiment.

  The driven roller bearing 41 is configured to come into contact with the bearing guide portion 17b by the tension of the belt 5 and regulate the position of the end portion of the driven roller 8 in the Z direction. The driven roller bearing 41 supports both ends of the driven roller 8, and the driven roller bearing 41 can move separately in the X direction. That is, the adjusting member 21 and the driven roller bearing 41 position each of the driven roller at both ends. Further, the driven roller bearing 41 is constituted by a rotatable cylindrical bearing, and the sliding resistance between the driven roller bearing 41 and the bearing guide portion 17b is reduced. Therefore, the driven roller bearing 41 can move smoothly in the X direction.

  In the present embodiment, the adjustment member 21 and the driven roller bearing 41 are configured as separate parts, and the tension of the belt 5 is supported by the driven roller bearing 41. That is, the tension of the belt 5 is configured not to act on the contact portion between the cam curved surface 21 b and the rubbing surface 22. Therefore, the tension of the belt 5 does not become the rotational load of the adjustment member 21, and the rotational load of the adjustment member 21 can be kept small.

  Here, in this embodiment, the cam curved surface 21b is made of polyacetal having high slidability, and the sliding resistance with the rubbing surface 22 is reduced. Therefore, the adjusting member 21 can rotate even if the rotational force received from the belt 5 is small. In the present embodiment, the cam rubbing surface 21b has a small radius. Therefore, the brake moment that suppresses the rotation of the adjusting member 21 can be reduced. That is, the rotational load on the adjustment member 21 can be reduced, and the adjustment member 21 can be rotated even if the rotational force received from the belt 5 is small.

  Thus, in the belt shift adjustment mechanism that tilts one of the plurality of stretching members to which the present invention can be applied with respect to the other stretching member, the one stretching member is limited to the tension roller 8. Instead, the driven roller 8 may be used.

(Embodiment 4)
In the first embodiment, the configuration in which the belt end portion 5a of the intermediate transfer belt 5 directly contacts the adjustment members 21L and R to transmit the force has been described. In the configuration in which the belt end portion 5a is in direct contact with the adjustment members 21L and 21R, when the difference between the rotation speed of the belt and the rotation speed of the adjustment member is large, the friction force due to the speed difference is generated at the belt end portion 5a. May work.

  On the other hand, in the present embodiment, a configuration will be described in which the belt end portion 5a moves the adjustment members 21L and 21R without contacting the adjustment members 21L and 21R to regulate the belt shift. Since other configurations are the same as those of the image forming apparatus according to the first embodiment, the same portions are denoted by the same reference numerals and described.

  As shown in FIG. 21A, the present embodiment is configured such that a rotational force transmission member 34A that receives a rotational force from the belt end 5a and transmits the force to the adjustment member 21 is interposed. The rotational force transmitting member 34A is made of, for example, polyacetal that is harder than the intermediate transfer belt 5, and rotates at substantially the same speed as the intermediate transfer belt 5 by contact with the belt end 5a. Since the rotation transmitting member 34A rotates at substantially the same speed as the intermediate transfer belt 5, there is no speed difference between the belt end 5a and the rotation transmitting member 34A at the belt end 5a, and the belt end in the belt moving direction. It is possible to reduce the frictional force generated in the portion 5a.

  Further, as shown in FIG. 21B, a rotational force transmission member 34C that engages with the tension roller sleeve 7b and rotates integrally may be provided instead of the rotation transmission member A.

  In both cases, the adjustment members 21L and R are rotated by the frictional force of the contact surface by being pressed against the adjustment members 21L and R by the belt end 5a only while receiving the shifting force from the intermediate transfer belt 5. Is possible.

  As a result, when adjusting the deviation of the belt, even if the rotational speeds of the adjusting members 21L and 21R and the rotational speed of the intermediate transfer belt 5a are different, the rotational force voltage members 34A and 34C are caused by the speed difference at the belt end 5a. It is possible to reduce the friction force.

(Other embodiments)
The image forming apparatus according to the above embodiment is an image forming apparatus including an intermediate transfer belt unit as a belt conveying device. However, the belt conveying device according to the present invention or the image forming apparatus including the belt conveying device is not limited thereto. That is, a conveyor belt unit including a conveyor belt that conveys a recording material onto which a toner image is directly transferred from a photosensitive drum may be used as the belt conveyor. Since the configuration of each image forming unit is the same as that of the image forming apparatus according to the first embodiment, description thereof is omitted.

  Specifically, the conveyance belt unit 160 includes the following. The conveying belt 110 that conveys the recording material, the driving roller 60 that drives and rotates the conveying belt 110 while the conveying belt 110 is stretched, and the biasing member that biases the conveying belt 110 while applying the tension. The tension roller 70 and the adjusting member 240 are provided.

  FIG. 22 shows a schematic configuration of an image forming apparatus according to another embodiment of the present invention. As shown in FIG. 22, in another embodiment, the recording material fed from the feeding tray is fed into the rotationally driven transport belt 110 at the timing of image formation.

  The recording material S carried on the conveyance belt 110 is conveyed to a transfer nip portion with each of the photosensitive drums 1a to 1d at a timing, and a toner image is directly transferred from the photosensitive drums 1a to 1d at the transfer nip. .

  In such a configuration, when a deviation occurs in the conveyance belt 110, the adjustment members 240L and 240R provided on the same axis as the tension roller of the conveyance belt 110 rotate to adjust the deviation of the conveyance belt 110. .

  With the above configuration, even in a belt conveyance device including the conveyance belt 110, it is possible to adjust the deviation of the belt with a small load on the belt.

  In the first to fourth embodiments, the connecting member that directly connects the adjusting members 21L and 21R has been described as the interlocking unit. However, if the adjustment member 21L (21R) is moved by receiving the belt bias when the belt is moved, the opposite adjustment member 21R (L) moves in the opposite direction by the same amount. A configuration other than the connecting member may be used. For example, the adjustment members 21L and 21R are each connected to a gear, and when the adjustment member 21L (R) rotates in response to the belt offset force, the gear also rotates. Then, after the rotational direction of the gear is converted to the reverse direction, the gear rotational force is transmitted to the gear connected to the reverse side adjustment member 21R (L), and the reverse side adjustment member 21R ( L) may rotate in the opposite direction by the same amount.

  With the above configuration, it is possible to adjust the deviation of the belt while the load on the belt is small.

5 Intermediate transfer belt 7 Tension roller 16 Intermediate transfer belt unit 18 Tension roller bearing 19 Tension roller bearing holder 21 Adjustment member 22 Cam sliding surface 23 Link member

Claims (12)

An endless belt that rotates, a first tension member that stretches the belt, and a second tension member that stretches the belt, wherein the belt moves in the moving direction of the belt. In the belt conveyance device that restricts the belt by tilting the first stretching member with respect to the second stretching member when approaching one end side in the orthogonal belt width direction,
The first tension member is provided on the one end side of the first tension member in the belt width direction, and regulates the position of the end portion on the one end side of the first tension member. A first adjustment member rotatable relative to,
The first tension member is provided on the other end side of the first tension member in the belt width direction and restricts the position of the end portion on the other end side of the first tension member. A second adjustment member rotatable relative to
Interlocking means for interlocking rotation of the second adjustment member with rotation of the first adjustment member;
When the belt approaches the one end side in the belt width direction, the first adjusting member receives a force from the belt and rotates in the rotational movement direction of the belt, and the second adjusting member is the interlocking unit. By rotating the first adjustment member in a direction opposite to the rotation direction of the first adjustment member, the first tension member is inclined with respect to the second tension member,
The interlocking means is configured so that the first adjustment member and the second adjustment member are in a state where the shift of the belt is restricted by inclining the first tension member with respect to the second tension member. An image forming apparatus that maintains a posture with respect to the first stretching member.   When the belt approaches the other end side in the belt width direction, the second adjustment member receives a force from the belt and rotates in the rotational movement direction of the belt, and the first adjustment member moves in the interlocking manner. The first tension member is inclined with respect to the second tension member by rotating in a direction opposite to the rotation direction of the second adjustment member by means. Belt conveyor.   The belt conveying apparatus according to claim 1, wherein the interlocking unit includes a connecting member that connects a part of the first adjusting member and a part of the second adjusting member.   4. The belt conveying device according to claim 3, wherein the connecting member is capable of swinging about a swing shaft provided in a substantially central region in the belt width direction.   The first tension member includes a roller that follows the movement of the belt, and the first and second adjustment members are rotatable with respect to the roller about a rotation axis of the roller. The belt conveyance device according to any one of claims 1 to 4, wherein the belt conveyance device is characterized.   A first bearing that pivotally supports the one end side of the rotating shaft of the roller, and a second bearing that pivotally supports the other end side of the rotating shaft of the roller, and the first adjustment member is The belt conveyance device according to claim 5, wherein the belt conveyance device is supported by a first bearing, and the second adjustment member is supported by the second bearing.   The said belt contacts the said 1st adjustment member in the belt edge part of the said one end side in the said belt width direction, when approaching the said one end side. The belt conveyance device according to one item.   8. The belt according to claim 1, wherein the first tension member is a tension roller that applies tension to the belt by being biased by a biasing unit. Conveying device.   The first tension member is a tension roller that applies tension to the belt by being urged by an urging means, and the first bearing and the second bearing can be rotated around a fulcrum. The belt support device according to claim 6, wherein the fulcrum is disposed below a bisector of a winding angle of the belt with respect to the tension roller.   The first adjustment member includes a first cam curved surface, and a region where the first cam curved surface is in contact changes, thereby regulating a position of the end portion on the one end side of the first tension member. The belt conveyance device according to any one of claims 1 to 9, wherein   The second adjustment member includes a second cam curved surface, and a region where the second cam curved surface comes into contact changes, whereby the position of the end portion on the other end side of the first tension member is changed. The belt conveying device according to claim 10, wherein the belt conveying device is regulated. A belt conveyance device and a plurality of image carriers each carrying a toner image of a different color, and transferring the toner image from the plurality of image carriers to the belt, or a transfer material conveyed by the belt An image forming apparatus for transferring a toner image,
12. The image forming apparatus according to claim 1, wherein the belt conveyance device is the belt conveyance device according to claim 1.

Images