JP5963425B2 - Belt conveying apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a belt conveying device that rotates an endless belt while being stretched by a plurality of stretching members, and more particularly to a belt conveying device used in an image forming apparatus such as a printer or a copying machine using an electrophotographic system. Is.

  2. Description of the Related Art Conventionally, among image forming apparatuses such as printers and copiers using an electrophotographic method, a belt conveyance device that rotates and moves an endless belt while being stretched by a plurality of stretching members (for example, rollers) is used. There was something that was there. In such a belt conveyance device, there is a problem that the belt is displaced in the longitudinal direction (axial direction of the stretching roller) when the belt is rotationally moved.

  As a technique for solving this problem, a configuration in which the deviation of the belt is eliminated by correcting the inclination of the stretching roller has been conventionally known.

  Patent Document 1 discloses a configuration in which at least one tension roller is supported on a shaft via a self-aligning bearing disposed on the inner side of a substantially central portion in the axial direction. In the configuration of Patent Document 1, a configuration is disclosed in which when the belt approaches, the moment on the left and right with respect to the axial center of the stretching roller collapses, and thereby the tilting of the stretching roller eliminates the belt misalignment. Yes.

JP 2004-203540 A

  However, in the configuration in which the self-aligning bearing is provided inside the tension roller as in Patent Document 1 and the tension roller is tilted, the tension roller is caused by friction between the tension roller inner surface and the self-aligning bearing during tilting. There arises a problem of moving in the roller axis direction (longitudinal direction). If the stretching roller that supports (contacts) the inner peripheral surface of the belt moves in the roller axial direction, the alignment effect may be reduced, and it is necessary to regulate the movement of the stretching roller in the roller axial direction. is there.

  Therefore, in the present invention, when the belt is close to one end in the longitudinal direction, the belt offset is corrected by inclining the rotation axis of the second tension member with respect to the rotation axis of the first tension member. An object of the present invention is to provide a belt conveyance device that eliminates belt misalignment while restricting movement of the second stretching member in the longitudinal direction. Furthermore, it aims at providing an image forming apparatus provided with the said belt conveying apparatus.

In order to solve the above problems, the present invention has the following configuration. A rotatable endless belt, a first stretching member that stretches the belt, a second stretching member that stretches the belt, and a longitudinal direction in which the belt is orthogonal to the rotational direction of the belt A belt correction section that corrects a shift of the belt by tilting the rotation shaft of the second stretching member with respect to the rotation shaft of the first stretching member when approaching one end side of the belt. In the transport device, the second stretching member includes a cylindrical belt contact body that is in contact with and supported by the inner peripheral surface of the belt, and a rotation shaft provided on the inner peripheral surface side of the belt contact body. And a contact body support portion that is fitted to the rotation shaft and supports an inner peripheral surface of the belt contact body, and a region that contacts the belt contact body of the contact body support portion is the rotation A belt conveying device which is inclined with respect to an axis.

Furthermore, another invention of the present application has the following configuration. An image carrier that carries a toner image, a rotatable endless belt, a first tension member that stretches the belt, a second tension member that stretches the belt, and the belt A deviation that corrects the deviation of the belt by tilting the rotation axis of the second tension member with respect to the rotation axis of the first tension member when approaching one end side in the longitudinal direction perpendicular to the rotation direction. An image forming apparatus that transfers a toner image on the image carrier to the belt or a transfer material conveyed by the belt, wherein the second stretching member includes: a correction unit; A cylindrical belt abutting body that contacts and supports the inner peripheral surface of the belt, a rotating shaft provided on the inner peripheral surface side of the belt abutting body, and the belt abutment fitted to the rotating shaft. A contact body support portion that supports an inner peripheral surface of the contact body, the contact body support An image forming apparatus wherein a belt abutting member that abuts a region of the is characterized in that is tilted with respect to the rotation axis.

  According to the present invention, when the belt approaches one end in the longitudinal direction, the belt offset is corrected by tilting the rotation shaft of the second stretching member with respect to the rotation shaft of the first stretching member. It is possible to provide a belt conveyance device that eliminates belt misalignment while restricting movement of the second stretching member in the longitudinal direction. Further, it is possible to provide an image forming apparatus including the belt conveying device.

Sectional drawing explaining the image forming apparatus which concerns on one Example of this invention The perspective view of the belt conveyance apparatus which concerns on one Example of this invention. The perspective view of the belt which concerns on one Example of this invention. Sectional drawing of the belt which concerns on one Example of this invention. 1 is a perspective view of a tension roller according to an embodiment of the present invention. (A) Cross-sectional view of a tension roller according to an embodiment of the present invention, (b) Enlarged cross-sectional view of a central region of the tension roller according to an embodiment of the present invention. Sectional drawing from the longitudinal direction of the tension roller which concerns on one Example of this invention (A) The figure which expanded the longitudinal direction center part of the full view cut | disconnected by the sectional line 50 of FIG. 2, (b) Sectional drawing cut | disconnected by the sectional line 51 of FIG.6 (b) The figure explaining the effect | action of the belt contact part of this invention Sectional drawing explaining the bearing inclination angle which concerns on one Example of this invention Schematic explaining a shift correction unit according to an embodiment of the present invention 1 is a schematic perspective view illustrating a shift correction unit according to an embodiment of the present invention. The figure explaining the belt conveyance apparatus which abbreviate | omitted the belt 1 which concerns on one Example of this invention. The perspective view explaining the belt conveyance apparatus which abbreviate | omitted the belt 1 which concerns on one Example of this invention. The figure explaining the state when the cam part which concerns on one Example of this invention contact | abuts to the stopper part. The figure explaining the inclination of the belt contact part which concerns on one Example of this invention. The perspective view explaining the tension roller and butting surface which concern on Example 2 of this invention. The figure explaining the abutting surface of Example 2 of this invention The perspective view of the belt conveyance apparatus which concerns on Example 2 of this invention. The perspective view explaining the tension roller and the butting surface according to the third embodiment of the present invention The figure explaining the abutting surface of Example 3 of this invention The perspective view of the belt conveyance apparatus which concerns on Example 3 of this invention.

Example 1
In the following, preferred embodiments of the present invention will be described in detail with reference to the drawings. However, the components described in this embodiment are merely examples, and are not intended to limit the scope of the present invention.

  First, the configuration of an image forming apparatus including the belt conveyance device according to the first embodiment as an intermediate transfer unit will be described with reference to FIGS.

  FIG. 1 shows a configuration of an image forming apparatus 100 provided with a belt conveying device according to the present invention as an intermediate transfer unit. The image forming apparatus 100 is an example of an electrophotographic color laser beam printer. However, the present invention is not limited to this, and can be widely applied to an image forming apparatus using an electrophotographic system. The image forming apparatus 100 transfers a transfer material 20 such as a recording sheet or an OHP sheet by electrophotography in accordance with an image signal sent from an external device such as a personal computer (not shown) connected to the image forming apparatus 100 so as to be communicable. A color image can be formed.

  In the image forming apparatus 100, as a plurality of image forming units, a plurality of image forming units 110Y, 110M, 110C, and 110K that respectively form yellow, magenta, cyan, and black toner images are linearly formed in a substantially horizontal direction. Is arranged. An intermediate transfer unit 120 serving as a belt conveying device is disposed so as to face each of the image forming units 110Y, 110M, 110C, and 110K. The intermediate transfer unit 120 is configured to be able to rotate and move a rotatable endless belt 1 formed of an intermediate transfer belt as an image carrying belt facing each of the image forming units 110Y, 110M, 110C, and 110K.

  As the belt 1 moves, the toner images formed by the image forming units 110Y, 110M, 110C, and 110K are sequentially transferred thereon. Thereafter, the image is transferred to the transfer material 20 at a time, whereby a color image in which a toner image having a desired number of colors is transferred to the transfer material 20 can be formed. Each of the image forming units 110Y, 110M, 110C, and 110K has the same configuration and operation except that the colors of the toner images to be formed are different. For this reason, in the following, unless it is particularly necessary to distinguish, the subscripts Y, M, C, and K are omitted to indicate that the element belongs to one of the image forming units 110Y, 110M, 110C, and 110K. The image forming unit 110 will be described as a representative. The same applies to the related image forming units.

  In the image forming unit 110, a toner image is formed by a known electrophotographic image forming process. In other words, the image forming unit 110 is provided with a photosensitive drum 111 made of a cylindrical electrophotographic photosensitive member as an image carrier on which an electrostatic latent image is formed so as to be rotatable in the direction of the arrow in FIG. In the image forming operation, first, the surface of the rotating photosensitive drum 111 is uniformly charged by a charging roller 112 serving as a charging unit.

  Next, a laser is emitted from a laser scanner 130 as an exposure unit in accordance with a signal sent from the computer, and an electrostatic latent image is formed on the photosensitive drum 111 by performing scanning exposure on the charged photosensitive drum 111. . To the electrostatic latent image formed on the photosensitive drum 111 (on the image carrier), a developing device 113 serving as a developing unit supplies toner as a developer, and develops the toner image into a visible image.

  The toner image formed on the photosensitive drum 111 is electrostatically transferred onto the belt 1 by the action of a primary transfer roller 121 serving as a primary transfer unit. The primary transfer roller 121 is disposed on the opposite side of the photosensitive drum 111 with the belt 1 provided in the intermediate transfer unit 120 serving as a belt conveying device in the primary transfer nip T1.

  The toner images formed on the photosensitive drums 111 of the respective image forming units 110 by the movement and timing of the belt 1 by the image forming process as described above are sequentially superimposed on the belt 1 and transferred.

  On the other hand, the transfer material 20 sent out from the transfer material container 140 by the pickup roller 141 and the like takes a timing at the registration roller 142, and the secondary transfer roller 143 serving as the secondary transfer means and the belt 1 come into contact with the secondary transfer roller 143. It is conveyed to the transfer nip T2. The toner image transferred onto the belt 1 is electrostatically transferred to the transfer material 20 by the action of the secondary transfer roller 143 at the secondary transfer nip portion T2.

  Next, the transfer material 20 is separated from the belt 1 and conveyed to the fixing unit 150, where the toner image on the transfer material 20 is pressurized and heated to be firmly fixed on the transfer material 20. Thereafter, the transfer material 20 is conveyed by the discharge roller 160 and discharged onto the discharge tray 170.

  In the image forming apparatus 100, the photosensitive drum 111, the charging roller 112, and the developing device 113 of each image forming unit 110 are integrally formed as a cartridge by a frame and configured as a process cartridge that can be attached to and detached from the image forming apparatus 100. Yes. The intermediate transfer unit 120 is also detachable from the image forming apparatus 100.

  Next, the configuration of the belt conveyance unit 200 in the intermediate transfer unit 120 serving as a belt conveyance device will be described. Here, the belt conveyance unit 200 shows a part of the intermediate transfer unit 120.

  First, the overall configuration of the belt of the belt conveyance unit 200 will be described with reference to FIG. FIG. 2 is a perspective view showing an appearance of the belt conveyance unit 200. The belt conveyance unit 200 includes a rotatable endless belt 1 and a first tension for driving the belt 1 as a plurality of tension members for stretching and supporting the belt 1 in a rotatable manner. A driving roller 2 is provided as a frame member. Furthermore, a driven roller 3 driven and rotated by the belt 1 and a tension roller 4 serving as a second stretching member are provided. That is, the belt 1 is rotatably stretched by three tension members.

  The driving roller 2 and the driven roller 3 are rotatably supported at both ends in the longitudinal direction by bearings 5a, 5b, 6a and 6b, respectively. Here, the longitudinal direction is a direction orthogonal to the rotation direction of the belt 1. The side plates 7a and 7b fixed to the apparatus frame hold the bearings 5a, 5b, 6a, and 6b that support the two rollers, respectively. The drive roller 2 is rotated by driving transmitted from a drive source such as a motor (not shown) provided in the image forming apparatus 100. As a result, the belt 1 rotates in the direction of arrow B in FIG. The driven roller 3 is driven and rotated by moving the belt 1 by the driving roller 2. The driven roller 3 is supported substantially parallel to the drive roller 2.

  The tension roller 4 which is the second tension member is held so as to be movable in the direction of arrow T in FIG. 2, and is biased in the T direction to move the belt 1 from the belt inner peripheral surface side to the outer peripheral surface side. Energized. More specifically, bearings 9 a and 9 b that support the rotation shaft 8 of the tension roller 4 are provided at both ends of the tension roller 4. The bearings 9a and 9b are slidably held along elongated bearing holding holes 10a and 10b provided in the side plates 7a and 7b, respectively. The bearings 9a and 9b are urged by springs 11a and 11b serving as elastic members as urging means, thereby applying tension to the belt 1. When the belt 1 is moved by the driving roller 2, the tension roller 4 is driven and rotated by the belt 1.

  The belt transport unit 200 includes a belt alignment mechanism as a shift correction unit that corrects the shift of the belt 1. The belt alignment mechanism of the present embodiment is configured so that the rotation shaft 2a that serves as the rotation center of the drive roller 2 and the rotation shaft 8 of the tension roller 4 when the belt 1 approaches a direction orthogonal to the rotation direction of the belt 1. The angle formed is changed.

  FIG. 3 is a perspective view showing the configuration of the belt 1, and FIG. 4 is a cross-sectional view of the belt 1 in the longitudinal direction. As shown in FIGS. 3 and 4, ribs 12 a and 12 b that are convex portions are attached to the inner peripheral surface side of the belt 1 at a longitudinal end portion with a separation interval La. The ribs 12 a and 12 b stand substantially vertically on the inner peripheral surface of the belt 1 and are continuously provided over the entire circumference of the belt 1.

Next, the configuration of the tension roller 4 will be described with reference to FIGS.
FIG. 5 is a perspective view of the tension roller 4, and FIG. 6A is a longitudinal sectional view of the tension roller 4. FIG.6 (b) is an enlarged view of the center part of the longitudinal direction of Fig.6 (a).

  As shown in FIG. 6, the tension roller 4 includes a hollow cylindrical sleeve 13 and a rotating shaft 8 (tension roller shaft 8) inserted into the sleeve 13. Both ends of the tension roller shaft 8 in the longitudinal direction are held by bearings 9a and 9b. The belt 1 is wound around the outer peripheral surface of the sleeve 13, and the sleeve 13 functions as a belt contact body that contacts the inner peripheral surface of the belt and supports the inner peripheral surface of the belt. At both ends of the sleeve 13, flange members 15 (15a, 15b) fixed to the sleeve 13 so as to rotate integrally with the sleeve 13 are provided. The flange member 15 has an inner diameter larger than that of the tension roller shaft 8 so that the sleeve 13 can be inclined with respect to the tension roller shaft 8.

  A contact body support portion is provided at a substantially central portion in the longitudinal direction of the tension roller shaft 8. The contact body support portion that is fitted to the tension roller shaft 8 and supports the inner peripheral surface of the sleeve 13 includes an inclined bearing inner ring 14a whose rotation shaft is inclined at a predetermined angle with respect to the axial direction of the tension roller shaft 8, and a sleeve. A contact portion 14 is provided. At this time, the inclined bearing inner ring 14a is rotationally stopped by a parallel pin (not shown) so as not to rotate with respect to the tension roller shaft 8, and is restricted by axial movement and an E ring (not shown). The sleeve contact portion 14 may be inclined by forming the tension roller shaft 8 and the inclined bearing inner ring 14a integrally and providing the inclined portion directly on the tension roller shaft 8.

  The sleeve 13 is supported by the sleeve contact portion 14 coming into contact with the sleeve 13 at a substantially central portion in the longitudinal direction. The sleeve contact portion 14 receives a biasing force from the springs 11a and 11b via the bearings 9a and 9b at both ends of the tension roller shaft 8, and supports the sleeve 13 from the inner peripheral surface side to the outer peripheral surface side. That is, the inner surface of the sleeve 13 is supported at one place by the sleeve contact portion 14 in the longitudinal direction. FIG. 7 is a cross-sectional view taken along the cross-sectional line 51 in FIG. 1 taken along the cross-sectional line 51 in FIG. As shown in FIG. 7, the tension direction is in contact with a contact portion W (a region in contact with the belt inner peripheral surface of the contact body support portion). Since the sleeve contact portion 14 has an outer diameter smaller than the inner diameter of the sleeve 13, the sleeve 13 can be inclined with respect to the sleeve contact portion 14.

  FIG. 8 is a view for explaining another inclined bearing inner ring 14a applicable to the present invention. FIG. 8A is an enlarged view of the central portion in the longitudinal direction of the full view cut along the sectional line 50 of FIG. FIG. 8B is a cross-sectional view taken along the cross-sectional line 51 in FIG. As shown in FIGS. 8A and 8B, the outer shape of the sleeve contact portion 14 may not be a columnar shape, but may be a shape such as a part of a spherical R surface of a sphere, for example. In that case, the outer shape of the sleeve contact portion 14 may be a part of a sphere having the same diameter as the inner diameter of the sleeve 13, and the sleeve 13 may be fitted.

  Next, an operation in which the sleeve 13 is shifted in one direction by tilting the rotation shaft of the sleeve contact portion 14 with respect to the rotation shaft of the tension roller shaft 8 will be described.

  9 illustrates the frictional force applied to the contact portion W (shaded portion) of the sleeve inner surface and the sleeve contact portion 14 through the sleeve 13 and the flange member 15 when viewed from the direction of the arrow 50 in FIG. Therefore, it is a diagram simply shown (the roller 16 is not shown). By driving the drive roller 2, the belt 1 starts to rotate, and accordingly, the sleeve 13 starts to rotate following the rotation axis Xb. At this time, the sleeve contact portion 14 is also driven to rotate by friction with the sleeve 13, but since the axis is inclined, the sleeve contact portion 14 rotates about the rotation axis Xc.

  Here, when the sleeve contact portion 14 rotates, in the region of the contact portion W, the sleeve contact portion 14 applies a frictional force Y to the sleeve 13 in the direction of the arrow. While the sleeve 13 is rotating, it always receives the axial component force Ya from the sleeve contact portion 14 and moves in the N direction. Then, by providing the abutting surface Z provided on the bearing 9a at the destination of the sleeve 13, the flange member 15a outside the sleeve 13 abuts against the abutting surface Z provided on the bearing 9a, so that the axial direction Is positioned.

  In the present invention, since the sleeve 13 is moved in one direction regardless of the direction and amount of inclination of the sleeve 13, in this embodiment, when trying to shift the sleeve 13 in the N direction in FIG. Takes a configuration satisfying the following conditional expression.

However,

It becomes.

Note that the symbols are the horizontal axis O, the axis Xa of the tension roller shaft, the rotation axis Xb of the sleeve 13 and the rotation axis Xc of the sleeve contact portion 14 in FIG. Furthermore, the angle θ _a formed by the axis Xa of the horizontal axis O and the tension roller shaft, the angle θ _b formed by Xa and Xb, the angle θ _c formed by Xa and Xc, the angle θ _{b max at which} the sleeve 13 is inclined _maximum , and the flange end surfaces on both sides , L, flange inner diameter (outer side) D, and shaft diameter d (at the flange end face). Here, the directions of the arrows θ _b and θ _c are positive with respect to the rotation direction.

  Further, the above formula is a conditional formula in which the direction in which the sleeve 13 approaches in the configuration of the present embodiment is specified in the N direction. However, in the case of being shifted in the M direction, the following formula may be satisfied. .

However,

It becomes.

  Further, in this embodiment, the bearing 4 is inclined with respect to the tension roller shaft 8, but the tension roller shaft 8 with which the bearing 4 is fitted coaxially may be inclined with respect to the sleeve 13, and at that time The conditions for shifting the sleeve 13 in the N direction are as follows.

However,

It becomes.

  Further, the above formula is a condition in which the direction in which the sleeve 13 approaches is specified in the N direction in the configuration in which the tension roller shaft 8 with which the bearing 4 is fitted coaxially is inclined with respect to the sleeve 13. In the case of displacing, a configuration satisfying the following expression may be used.

However,

It becomes.

  In the first embodiment, the sleeve 13 can be shifted in a predetermined direction by the inclined bearing inner ring 14a inclined to the tension roller shaft 8 included in the tension roller 4 and the sleeve contact portion 14 that contacts the inner peripheral surface of the sleeve. is there.

  Next, the configuration and operation of the shift correction unit of this embodiment will be described. The shift correction unit of the present embodiment is configured to automatically change the direction of the axis of the sleeve 13 in a direction to eliminate the shift of the belt, and is an automatic alignment unit.

  Rollers 16 (16a, 16b) are fitted to the flange member 15 so as to be rotatable with respect to the flange member 15. That is, the roller 16 can freely rotate coaxially with the sleeve 13 and the flange member 15. FIG. 11 is an enlarged view of both ends of the tension roller 4, and FIG. 12 is a perspective view of one end of the tension roller 4.

  As shown in FIGS. 11 and 12, the roller 16 a includes a belt contact portion 16 c having an outer diameter substantially the same as the outer diameter of the sleeve 13 in a state of being fitted to the flange member 15. Further, the roller 16 includes a rib separation portion 16d having an outer diameter smaller than that of the belt contact portion 16c so that a step larger than the height of the rib 12 can be formed with respect to the belt contact portion 16c. Further, a rib contact portion 16e formed of a slope connecting the belt contact portion 16c and the rib separation portion 16d is provided. The rib contact portion 16e may be configured by a surface perpendicular to the axial direction of the roller 16a. As shown in FIG. 11, the belt 1 and the rib 12 do not contact the rib separating portion 16d. Further, when the belt 1 moves in the left-right direction in the figure, the side surface of the rib 12 comes into contact with the rib contact portion 16e. In the present embodiment, the angle of the rib contact portion 16e is set to an angle of 80 degrees with respect to the axial direction. Similarly to the roller 16a, the roller 16b includes a belt contact portion 16c, a rib separation portion 16d, and a rib contact portion 16e. Further, the interval La between the ribs 12 provided on the belt 1 is set to be larger than the width Lb of the position where the ribs 12 of the rib contact portions 16e of the rollers 16 on both sides abut, and only one of the ribs 12 is provided. Is in contact with the rib contact portions 16e of the rollers 16a and 16b.

  A cam portion 16f is provided on the outer side of the belt separating portion 16d of the roller 16, and the cam portion 16f is located on the outer side in the belt longitudinal direction.

  FIG. 13 is a diagram in which the belt 1 is omitted from the belt conveyance unit 200. The side plates 7a and 7b are each provided with a stopper portion 17 (17a and 17b) with which the cam portion 16f abuts. When the tip of the cam portion 16D hits the stopper portion 17, the rotation of the roller 16 is restricted. At this time, since the roller 16 can freely rotate with respect to the flange member 15 and the sleeve 13, even if the rotation of the roller 16 stops, the flange member 15 and the sleeve 13 holding the roller 16 are driven by the belt. Can continue to rotate.

  Next, with reference to FIGS. 14-16, the effect | action of the shift correction | amendment part of a present Example is demonstrated.

  FIG. 14 is a diagram in which the belt 1 is omitted from the belt conveyance unit 200. The description will be made on the assumption that the belt 1 is driven by the driving roller 2 and is rotationally moved in the direction of the arrow Bf. With the configuration as described above, when the belt 1 moves in the M direction or the N direction, the ribs 12 provided on the belt 1 come into contact with the rollers 16 and a rotational force is applied to the rollers 16. Since the rib 12 is provided outside the rib contact portion 16e, when the belt 1 moves in the right direction (arrow M direction) in the figure, the belt 16 moves to the left side of the figure, and the belt 1 moves to the left in the figure ( When moving in the direction of arrow N), rotational force is applied to the roller 16b on the right side of the figure.

  FIG. 15 is a diagram for explaining a state when the cam portion 16 f of the roller 16 abuts against the stopper portion 17. As shown in FIG. 15, the roller 16 tries to rotate in the direction of arrow E by the rotational force received from the rib 12, but cannot be rotated when the cam portion 16 f hits the stopper portion 17. It is pushed up to the position. When the roller 16 is pushed up, the flange member 15 fitted coaxially with the roller 16 and the end portion of the sleeve 13 fixed to the flange member 15 are also lifted.

  FIG. 16 is a cross-sectional view showing a state when the tension roller 4 is cut at the cross-sectional line 50 in FIG. When the roller 16a on the left side of FIG. 16 acts as shown in FIG. 15, it rotates in the direction of arrow F with the sleeve contact portion 14 as a fulcrum and tilts from the position of the broken line to the position of the solid line.

  Here, the case where the belt 1 approaches the arrow M direction will be described. In this case, the rib 12a on the left side of the drawing contacts the roller 16a, and a rotational force is applied to the roller 16a by the frictional force between the rib 12a and the rib contact portion 16e of the roller 16a. However, the roller 16a cannot rotate because the cam portion 16f abuts against the stopper portion 17a, and as described above, the flange member 15a and the end of the sleeve 13 are moved in the direction of arrow G (upward), and the sleeve 13 becomes the sleeve contact portion. Tilt 14 to the fulcrum. At this time, the end on the right side of the figure on the opposite side of the sleeve 13 moves in the direction of arrow H (downward), but the roller 16b is not in contact with the rib 12b and no rotational force is applied. It does not interfere with movement in the H direction.

  When the sleeve 13 is inclined with respect to the driving roller 2 and the driven roller 3 in this way, the belt 1 is less inclined in the direction of the arrow M, and conversely starts to move in the direction of the arrow N, so the rib 12a is the rib of the roller 16a. It separates from the contact part 16e.

  By this action, when the belt 1 is initially moved in the direction of the arrow M in the figure, the direction of the shaft of the sleeve 13 with respect to the shaft of the drive roller 2 is adjusted in a direction that cancels out the tendency until the contact between the rib 12a and the roller 16a disappears. Is done.

  Similarly, when the belt 1 moves in the direction of the arrow N (the opposite direction to the above), the side surface of the rib 12b comes into contact with the opposite roller 16b, and the sleeve 13 is inclined in the opposite direction by the same action. As a result, the belt 1 moves in the direction of the arrow M.

  In this way, the rib 12 attached to the belt comes into contact with the roller 16 when the belt 1 is offset, and a rotational force is applied to the roller 16, and the sleeve 13 and the tension roller rotating shaft 8 are inclined directly by the roller 16. be able to. That is, the offset force of the belt 1 can be directly converted into a force for inclining the tension roller 4, and as a result, the tension roller 4 can be inclined with respect to the driving roller 2 and the driven roller 3.

  When the tension roller 4 is tilted by the shift correction unit, if the sleeve 13 that contacts the inner peripheral surface of the tension roller moves in the longitudinal direction, a frictional force acts on the inner peripheral surface of the belt 1 that contacts the tension roller, and the shift is caused. The correction force of the correction unit is reduced. However, in this embodiment, the sleeve 13 of the tension roller 4 is offset in one longitudinal direction by the abutting body support portion, so that even if the tension roller 4 is tilted, the shift is reliably corrected. The force can be transmitted to the inner peripheral surface of the belt.

  In the present embodiment, the belt conveyance unit 200 is described as using three rollers. However, in the present invention, at least two rollers of the driving roller 2 and the tension roller 4 are sufficient. Further, even in the case of three or more rollers, it is possible to operate the aligning action of the belt 1 by providing the mechanism of the tension roller 4 of this embodiment in at least one roller.

  As described above, according to this embodiment, when the belt approaches one end side in the longitudinal direction, the belt is offset by inclining the rotation shaft of the second stretching member with respect to the rotation shaft of the first stretching member. In the configuration to be corrected, it is possible to provide a belt conveyance device that eliminates belt misalignment while restricting movement of the second stretching member in the longitudinal direction. Further, it is possible to provide an image forming apparatus including the belt conveying device.

(Example 2)
Next, another embodiment of the present invention will be described with reference to FIGS. In this embodiment, since the basic configuration of the image forming apparatus to which the present invention is applied and the belt conveyance unit included in the image forming apparatus is the same as that of the first embodiment, the same or corresponding functions as those of the first embodiment. , Elements having a configuration are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 17 is an enlarged view of one side of the tension roller 4 according to the present embodiment (however, the belt 1, the rib 12a, and the roller 16a are omitted), and a part of the abutting surface Z of the first embodiment. The abutting surface convex portion Za is provided. FIG. 18 is a schematic view seen from the direction of the arrow 61 when cut along the cut surface 60.

  The description of FIGS. 17 to 18 is an explanatory diagram in which an abutment surface Z that abuts against the flange member 15 and an abutment protrusion Za are provided at the left end of the tension roller 4 in FIG. Also in this embodiment, since the configuration of the bearing portion of the tension roller 4 is inclined with respect to the tension roller shaft 8 with respect to the tension roller shaft 8 as in the first embodiment, the sleeve 13 moves in the direction of the arrow N. It is put away. When the sleeve 13 moves in the direction of arrow N, the flange member 15a also moves in the N direction. When the end surface 15c of the flange member 15a comes into contact with the abutting surface convex portion Za, the axial movement stops, and both of them rotate in the direction of the arrow V while being in contact with each other.

  The relationship between the force applied to the flange member 15a and the abutting surface convex portion Za will be described with reference to FIG. The flange member 15a rotates in the direction of the arrow V while sliding with the flange member end surface 15c in the region 22 of the abutting surface convex portion Za. In the region of both contact surfaces 22, the flange member end surface 15c applies a frictional force to the abutting surface convex portion Za in the direction U, and conversely, the flange member end surface 15c extends from the abutting surface convex portion Za to the UN. The reaction force of the frictional force is received in the direction. As a result, the flange member 15a tilts together with the sleeve 13 in the direction of the arrow P. Since the tension is applied with a large force in the T direction, the amount of frictional force generated here can be ignored in the T direction. As a result, as shown in FIG. 19, the sleeve 13 is tilted so that the left end thereof moves downward (arrow P direction) and the right end moves upward (arrow R direction). Therefore, the belt 1 that rotates and moves in the arrow Bf direction is offset in the arrow M direction (one end side direction).

  When the belt 1 approaches the arrow M direction, as described in the first embodiment, the rib 12a comes into contact with the roller 16a and a rotational force is applied to the roller 16a, so that the left end of the sleeve 13 is moved upward (arrow Q direction). A force is generated to move the By setting the frictional force by the flange member end surface 15c to be sufficiently smaller than the force by which the sleeve 13 is lifted by the roller 16a, the roller 13a causes the sleeve 13 to move upward on the left side (in the direction of the arrow Q) and downward on the right side. Tilt to move in the direction of arrow S). As a result, the belt 1 starts to move in the direction of arrow N (the direction of the other end) in the opposite direction.

  When the belt 1 moves in the direction of the arrow N, the rib 12a is separated from the roller 16a and the rotational force applied to the roller 16a is lost, so that the roller 16a does not act to lift the left end of the sleeve 13. Therefore, the sleeve 13 is inclined again so that the left end moves downward (arrow P direction) and the right end moves upward (arrow R direction) due to the frictional force of the flange member end face 15c, and the belt 1 again in the arrow M direction. Start moving.

  Thus, when the belt 1 moves in the direction of arrow M, the belt 16 moves in the direction of arrow N by the action of the roller 16a, and when moved in the direction of arrow N, the belt 1 is used for tilting the frictional force of the flange member end face 15c. The inclination of the sleeve 13 is corrected so as to move in the direction. By repeating this, it is possible to prevent the belt 1 from continuing to move toward one side.

  Therefore, the rib 12b and the roller 16b on the opposite side are not required, and the belt 1 can be prevented from being displaced by providing the alignment mechanism of the present invention only on one side of the tension roller 4, so that the configuration can be further improved. Simplification and cost reduction are possible. In the description, the configuration in which the abutting surface Z and the abutting convex portion Za are provided on the left end portion of the tension roller 4 has been described, but the configuration may be provided on the right end portion side of the tension roller 4.

(Example 3)
Next, another embodiment of the present invention will be described with reference to FIGS. In this embodiment, since the basic configuration of the image forming apparatus to which the present invention is applied and the belt conveyance unit included in the image forming apparatus is the same as that of the first embodiment, the same or corresponding functions as those of the first embodiment. , Elements having a configuration are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 20 is an enlarged view of one side of the tension roller 4 according to the third embodiment of the present invention. (However, the belt 1, the rib 12a, and the roller 16a are omitted). A part of the abutting surface Z of Example 1 is provided with an abutting surface Zb made of a member having a friction coefficient different from that of the bearing 9a, and the abutting surfaces Z and Zb are substantially in the same plane. At this time, the material is selected so that the friction coefficient of the abutting surface Zb is sufficiently larger than the friction coefficient of other portions of the abutting surface Z. Note that the surface roughness of the Zb portion may be changed so that the friction coefficient is sufficiently larger than that of the Z portion without changing the friction coefficient by changing the material between the abutting surface Z and the abutting surface Zb.

  FIG. 21 is a diagram viewed from the 61 direction when the cutting surface 60 is cut, and is a relationship diagram of forces related to the tilting mechanism of the sleeve 13. Here, the case where this tilting mechanism is provided on the left side of FIG. 13 will be described. Also in this embodiment, since the configuration of the bearing portion of the tension roller 4 is inclined with respect to the tension roller shaft 8 with respect to the tension roller shaft 8 as in the first embodiment, the sleeve 13 moves in the direction of the arrow N. It is put away. When the sleeve 13 moves in the direction of the arrow N, the axial movement stops when the end face 15c of the flange member 15a comes into contact with the abutting surfaces Z and Zb. Become.

  The relationship between the force applied to the flange member 15a and the abutting surfaces Z and Zb at this time will be described with reference to FIG. The flange member 15a rotates in the direction of arrow V while sliding with the flange member end surface 15c in the region of the abutting surfaces Z and 23 and in the region of Zb and 22. The flange member end surface 15c gives a frictional force in the direction of U23 to the abutting surface Z in the region of the abutting surface 23, and gives a frictional force in the direction of U22 to the abutting surface Zb in the region of the abutting surface 22. ing. On the contrary, the flange member end surface 15c receives the reaction force of the frictional force from the abutting surface Z toward U23N in the region of the abutting surface 23, and in the region of the abutting surface 22 from the abutting surface Z to U22N. The reaction force of the frictional force is received in the direction. However, at this time, the friction coefficient of the abutting surface Z is set to be sufficiently smaller than the friction coefficient of the abutting surface Zb, so the frictional force applied to the contact surface 23 is sufficiently small and can be ignored. As a result, it is considered that only the reaction force of the frictional force is applied to the flange member 15a in the U22N direction. Therefore, the flange member 15 a tilts in the direction of the arrow P together with the sleeve 13.

  Since the tension is applied with a large force in the T direction, the amount of frictional force generated here can be ignored in the T direction. As a result, as shown in FIG. 22, since the left end of the sleeve 13 is inclined downward (arrow P direction) and the right end is moved upward (arrow R direction), Similar effects can be obtained.

  That is, the belt 1 moves in the direction of the arrow N by the action of the roller 16a when moved in the direction of the arrow M, and moves in the direction of the arrow M for tilting the frictional force of the flange member end face 15c when moved in the direction of the arrow N. The inclination of the sleeve 13 is corrected so as to move. By repeating this, it is possible to prevent the belt 1 from continuing to move toward one side.

  Therefore, the rib 12b and the roller 16b on the opposite side are not required, and the belt 1 can be prevented from being displaced by providing the alignment mechanism of the present invention only on one side of the tension roller 4, so that the configuration can be further improved. Simplification and cost reduction are possible. In the description, the configuration in which the abutting surface Z and the abutting convex portion Za are provided on the left end portion of the tension roller 4 has been described, but the configuration may be provided on the right end portion side of the tension roller 4.

  The belt conveyance device of the above embodiment has been described as the intermediate transfer belt unit 200, but may have other configurations. Specifically, a transfer material conveyance belt unit used in an image forming apparatus that directly transfers a toner image from a photosensitive drum to a transfer material to be conveyed, or a conveyance belt unit that conveys a transfer material to a secondary transfer nip portion. The present invention is also applicable to the above.

DESCRIPTION OF SYMBOLS 1 Belt 4 Tension roller 8 Tension roller axis | shaft 12a, 12b Rib 13 Sleeve 14a Inclined bearing inner ring 15 Flange member 15c Flange member end surface 16a, 16b Roller 17a, 17b Stopper part

Claims (15)

A rotatable endless belt, a first stretching member that stretches the belt, a second stretching member that stretches the belt, and a longitudinal direction in which the belt is orthogonal to the rotational direction of the belt A belt correction section that corrects a shift of the belt by tilting the rotation shaft of the second stretching member with respect to the rotation shaft of the first stretching member when approaching one end side of the belt. In the transport device,
The second tension member includes a cylindrical belt abutting body that contacts and supports the inner circumferential surface of the belt, a rotation shaft provided on the inner circumferential surface side of the belt abutting body, and the rotation A contact body support portion that is fitted to a shaft and supports an inner peripheral surface of the belt contact body, and a region of the contact body support portion that contacts the belt contact body is in relation to the rotation shaft A belt conveying device which is inclined.   The belt includes a rib on an inner peripheral surface of the belt, and the shift correction portion is connected to a rib contact portion and a rib contact portion that contact the rib when the belt approaches one end side in the longitudinal direction. The belt conveyance device according to claim 1, further comprising a cam portion.   The deviation correction unit is configured such that the rib provided on the inner peripheral surface on the other end side of the belt abuts on the one end side in the longitudinal direction, and the rib contact part abuts on the belt. The rotation axis of the second tension member is inclined with respect to the rotation axis of the first tension member by rotating the rib contact portion and the cam portion by force. The belt conveyance apparatus as described in.   The said contact body support part is provided with the inclination bearing inclined by predetermined angle with respect to the said rotating shaft, The said area | region is supported by the said inclination bearing, The Claim 1 to Claim 3 characterized by the above-mentioned. The belt conveyance apparatus as described in any one. The second tension member includes a flange that supports an inner peripheral surface of an end portion of the belt contact body in the longitudinal direction,
An abutting surface that abuts against an end surface of the flange on an end side in the longitudinal direction of the second tension member;
The belt conveyance device according to claim 1, wherein the position of the belt contact body in the longitudinal direction is regulated by contacting an end surface of the flange with the abutting surface.   The belt conveying device according to claim 5, wherein a part of the abutting surface is a convex portion, and an end surface of the flange abuts on the convex portion.   The belt conveyance device according to claim 5, wherein a friction coefficient of at least a part of the abutting surface in contact with the flange is higher than a friction coefficient of the other part in contact.   The belt contact device according to any one of claims 1 to 7, wherein the contact body support portion is provided at a center of the belt in the longitudinal direction. An image carrier that carries a toner image, a rotatable endless belt, a first tension member that stretches the belt, a second tension member that stretches the belt, and the belt A deviation that corrects the deviation of the belt by tilting the rotation axis of the second tension member with respect to the rotation axis of the first tension member when approaching one end side in the longitudinal direction perpendicular to the rotation direction. An image forming apparatus that transfers a toner image on the image carrier to the belt or a transfer material that is conveyed by the belt.
The second tension member includes a cylindrical belt abutting body that contacts and supports the inner circumferential surface of the belt, a rotation shaft provided on the inner circumferential surface side of the belt abutting body, and the rotation A contact body support portion that is fitted to a shaft and supports an inner peripheral surface of the belt contact body, and a region of the contact body support portion that contacts the belt contact body is in relation to the rotation shaft An image forming apparatus characterized by being inclined.   The belt includes a rib on an inner peripheral surface of the belt, and the shift correction portion is connected to a rib contact portion and a rib contact portion that contact the rib when the belt approaches one end side in the longitudinal direction. The image forming apparatus according to claim 9, further comprising a cam portion.   The deviation correction unit is configured such that the rib provided on the inner peripheral surface on the other end side of the belt abuts on the one end side in the longitudinal direction, and the rib contact part abuts on the belt. The rotation axis of the second tension member is inclined with respect to the rotation axis of the first tension member by rotating the rib contact portion and the cam portion by force. The image forming apparatus described in 1.   The said contact body support part is provided with the inclination bearing inclined by predetermined angle with respect to the said rotating shaft, The said area | region is supported by the said inclination bearing, Any of Claim 9 to 11 characterized by the above-mentioned. The image forming apparatus according to claim 1. The second tension member includes a flange that supports an inner peripheral surface of an end portion of the belt contact body in the longitudinal direction,
An abutting surface that abuts against an end surface of the flange on an end side in the longitudinal direction of the second tension member;
The image forming apparatus according to claim 9 , wherein the position of the belt contact body in the longitudinal direction is regulated by contacting an end surface of the flange with the abutting surface.   The image forming apparatus according to claim 13, wherein a part of the abutting surface is a convex portion, and an end surface of the flange is in contact with the convex portion.   The image forming apparatus according to claim 13, wherein a friction coefficient of at least a part of the abutting surface in contact with the flange is higher than a friction coefficient of the other part in contact.

Images