JP2017120338A - Belt conveyance device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a belt conveyance device that employs a rib regulation system and can suppress damage to the ends in the width direction of a belt, and an image forming apparatus.SOLUTION: A belt conveyance device 1 comprises: an endless belt 2; ribs 6 that are provided on the inner peripheral surfaces in the width direction of the belt 2; a plurality of stretch rollers 3, 4, and 5 that stretch the belt 2; and regulation members 8 that are arranged at the ends in the rotation axis direction of at least one stretch roller 5 and can be in contact with the ribs 6. The regulation member 8 includes a first regulation surface 8a that is in contact with the rib 6 to regulate a movement in the rotation axis direction of the stretch roller 5 of the rib 6, and a second regulation surface 8b that is in contact with the rib 6 to regulate a movement to the inside in the radial direction of the stretch roller 5 of the rib 6.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a belt conveying device used in an image forming apparatus such as a copying machine, a printer, and a facsimile apparatus using an electrophotographic method or an electrostatic recording method, and an image forming apparatus including the belt conveying device.

  2. Description of the Related Art Conventionally, in an image forming apparatus using, for example, an electrophotographic method or an electrostatic recording method, a belt conveying device including an endless belt (hereinafter also simply referred to as “belt”) stretched around a plurality of stretch rollers. Is used. The belt is used as a conveyance body that carries and conveys a toner image, and carries and conveys a transfer material on which the toner image is formed. Examples of the conveyance body that carries and conveys a toner image include a belt-shaped electrophotographic photosensitive member (photosensitive belt), a belt-shaped electrostatic recording dielectric (electrostatic recording dielectric belt), and a belt-shaped intermediate transfer member ( Intermediate transfer belt). Further, examples of the conveyance member that carries and conveys the transfer material on which the toner image is formed include a transfer material carrier (transfer material carrying belt) that carries and conveys the transfer material onto which the toner image is transferred from the photosensitive member. is there.

  A belt conveying apparatus having an intermediate transfer belt used in an electrophotographic image forming apparatus will be further described as an example. In this type of belt conveyance device, the intermediate transfer belt moves in the width direction (a direction substantially orthogonal to the conveyance direction) when the intermediate transfer belt is conveyed (circulated and driven) while being stretched by a plurality of tension rollers. A phenomenon called “belt shift” may occur. When the belt is displaced, there is a risk that a problem occurs such that the end portion in the width direction of the intermediate transfer belt comes into contact with other members and is damaged.

  Therefore, as described in Patent Document 1, a rib is provided on the inner peripheral surface of the end portion in the width direction of the intermediate transfer belt, and a regulating member that can contact the rib is provided on the end portion in the rotation axis direction of the stretching roller. In some cases, a rib regulation system that regulates the belt deviation is used. By making the regulating surface in contact with the rib of the regulating member an inclined surface (tapered surface), it is possible to suppress the rib from riding on the stretching roller. Further, as described in Patent Document 1, in order to prevent damage to the end portion in the width direction of the intermediate transfer belt, a reinforcing tape may be attached to the outer peripheral surface of the end portion in the width direction of the intermediate transfer belt. is there.

JP 2009-122389 A

  However, the risk of damage to the intermediate transfer belt tends to increase due to the thinning of the intermediate transfer belt.

  In the rib regulating method described above, the rib contacts the regulating surface of the regulating member and the belt side is regulated, but when the rib is not in contact with the regulating surface, the end of the intermediate transfer belt in the width direction is It becomes a state where it is easy to bend inward in the radial direction of the tension roller. For this reason, stress tends to concentrate on the bent portion, which may cause damage to the intermediate transfer belt.

  Even if a reinforcing tape is attached to the end of the intermediate transfer belt in the width direction, the boundary inside the reinforcing tape in the width direction of the intermediate transfer belt tends to concentrate stress, and an external force is applied to the intermediate transfer belt. May break.

  For example, the image forming apparatus may be provided with a belt cleaning device for collecting residual toner on the intermediate transfer belt. An end seal in pressure contact with the intermediate transfer belt may be provided at the end of the belt cleaning device in the width direction of the intermediate transfer belt to prevent the collected toner from leaking. When the region where this end seal presses the intermediate transfer belt is applied to the portion corresponding to the tapered surface of the regulating member or the boundary portion of the reinforcing tape, the above-mentioned bending and stress concentration are promoted, There is a high possibility of causing damage to the intermediate transfer belt.

  In the above, the conventional problem has been described by taking the intermediate transfer belt as an example. However, the same problem may occur in the belt conveyance device in which the belt has other functions as described above.

  Accordingly, an object of the present invention is to provide a belt conveyance device and an image forming apparatus capable of suppressing the damage of the end portion in the width direction of the belt in the configuration adopting the rib regulating method.

  The above object is achieved by the belt conveyance device and the image forming apparatus according to the present invention. In summary, the present invention provides an endless belt, a rib provided on an inner peripheral surface of an end portion in the width direction of the belt, a plurality of stretching rollers that stretch the belt, and the plurality of tensioning belts. A belt conveying device having a regulating member which is disposed at an end in the rotation axis direction of at least one of the stretching rollers, and is capable of contacting the rib, wherein the regulating member is in contact with the rib. A first restricting surface for restricting movement of the at least one stretching roller in the rotation axis direction of the rib; and movement of the rib inward in the radial direction of the at least one stretching roller in contact with the rib. And a second regulating surface that regulates the belt conveying device.

  According to another aspect of the present invention, there is provided an image forming apparatus comprising the belt conveyance device of the present invention, and a toner image forming means for forming a toner image on the belt or a transfer material carried on the belt. .

  According to the present invention, in the configuration adopting the rib regulation method, it is possible to suppress damage to the end portion in the width direction of the belt.

1 is a schematic sectional view of an image forming apparatus. FIG. 4 is a perspective view of an intermediate transfer belt unit. FIG. 4 is a schematic perspective view showing a cross section of an intermediate transfer belt. It is an expansion perspective view of the edge part of a tension roller. It is sectional drawing of a belt cleaning apparatus. It is a perspective view of a color. It is a side view near the end of the tension roller. It is a schematic diagram which shows the behavior of the belt in a present Example and a comparative example. It is a side view of the other example of a color. It is a schematic diagram which shows the other arrangement | positioning aspect of a color. It is a schematic sectional drawing of the principal part of the other example of an image forming apparatus.

  Hereinafter, the belt conveyance device and the image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

[Example 1]
1. FIG. 1 is a schematic sectional view of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus 100 according to the present exemplary embodiment is a tandem type laser beam printer that employs an intermediate transfer method that can form a full-color image using an electrophotographic method.

  The image forming apparatus 100 forms first, second, and second images that form yellow (Y), magenta (M), cyan (C), and black (K) images as a plurality of image forming units (stations), respectively. 3 and a fourth image forming unit SY, SM, SC, SK. In this embodiment, the configurations and operations of the image forming units SY, SM, SC, and SK are substantially the same except that the color of toner used in the developing process described later is different. Therefore, hereinafter, unless there is a particular need for distinction, Y, M, C, and K at the end of a symbol representing an element for any color will be omitted, and the element will be described generally.

  The image forming unit S includes a photosensitive drum 11 which is a rotatable drum type (cylindrical) photosensitive member (electrophotographic photosensitive member) as an image carrier. The photosensitive drum 11 is rotationally driven in the direction of arrow R1 (clockwise) in the drawing. In each image forming unit S, the following devices are arranged around the photosensitive drum 11. First, a charging roller 12 that is a roller-shaped charging member as a charging unit is disposed. Further, an exposure device (laser scanner device) 13 as an exposure unit is arranged. Further, a developing device 14 as a developing unit is disposed. Further, a primary transfer roller 15 which is a roller-shaped primary transfer member as a primary transfer unit is disposed. Further, a drum cleaning device 16 as a photosensitive member cleaning unit is disposed. The exposure device 13 is configured as one unit that exposes the photosensitive drums 11Y, 11M, 11C, and 11K.

  In addition, the image forming apparatus 100 includes an intermediate transfer belt unit 1 serving as a belt conveyance device disposed so as to face each of the photosensitive drums 11Y, 11M, 11C, and 11K. The intermediate transfer belt unit 1 has an intermediate transfer belt 2 formed of an endless belt as an intermediate transfer member so as to face each of the photosensitive drums 11Y, 11M, 11C, and 11K. The intermediate transfer belt 2 is stretched around a driving roller 3, a driven roller 4, and a tension roller 5 as a plurality of stretching rollers (supporting members). The intermediate transfer belt 2 rotates (circulates) in the direction of arrow R2 (counterclockwise) in the figure when the driving roller 3 is driven to rotate. Here, the rotation (circular movement) direction of the intermediate transfer belt 2 is also referred to as a conveyance direction. The tension roller 5 is urged from the inner peripheral surface side to the outer peripheral surface side of the intermediate transfer belt 2 as indicated by an arrow T in the drawing, whereby a predetermined tension (tension) is applied to the intermediate transfer belt 2. It has been. The primary transfer rollers 15Y, 15M, 15C, and 15K described above are disposed on the inner peripheral surface side of the intermediate transfer belt 2 at positions facing the photosensitive drums 11Y, 11M, 11C, and 11K. The primary transfer roller 15 is urged (pressed) with a predetermined pressure toward the photosensitive drum 11 via the intermediate transfer belt 2 to form a primary transfer portion N1 where the intermediate transfer belt 2 and the photosensitive drum 11 are in contact with each other. Further, on the outer peripheral surface side of the intermediate transfer belt 2, a secondary transfer roller 17 that is a roller-like secondary transfer member as a secondary transfer unit is disposed at a position facing the driving roller 3. The secondary transfer roller 17 is biased (pressed) toward the driving roller 3 via the intermediate transfer belt 2 with a predetermined pressure, and the secondary transfer portion N2 where the intermediate transfer belt 2 and the secondary transfer roller 17 are in contact with each other. Form. Further, on the outer peripheral surface side of the intermediate transfer belt 2, a belt cleaning device 18 as an intermediate transfer member cleaning unit is disposed at a position facing the tension roller 5.

  In addition, the image forming apparatus 100 is provided with a feeding / conveying device 20 that supplies the transfer material P to the secondary transfer portion N2, a fixing device 19 that fixes the toner image on the transfer material P, and the like.

  At the time of image formation, the surface of the rotating photosensitive drum 11 is uniformly charged to a predetermined potential having a predetermined polarity (negative polarity in this embodiment) by the charging roller 12. The surface of the charged photosensitive drum 11 is scanned and exposed by the exposure device 13 according to the image information, and an electrostatic latent image (electrostatic image) is formed on the photosensitive drum 11. The electrostatic latent image formed on the photosensitive drum 11 is developed (visualized) using toner as a developer by the developing device 14, and a toner image is formed on the photosensitive drum 11. In this embodiment, the charged polarity of the photosensitive drum 11 (negative polarity in this embodiment) is applied to the exposed portion (bright portion) on the photosensitive drum 11 that is exposed after being uniformly charged and exposed to a lower absolute value of the potential. The toner charged to the same polarity as that adheres (reversal development).

  The toner image formed on the photosensitive drum 11 is transferred (primary transfer) onto the rotating intermediate transfer belt 2 by the action of the primary transfer roller 15 in the primary transfer portion N1. At this time, the primary transfer roller 15 is applied with a primary transfer voltage (primary transfer bias) that is a DC voltage having a polarity (positive in this embodiment) opposite to the toner charging polarity during development. For example, when forming a full-color image, the toner images formed on the respective photosensitive drums 11Y, 11M, 11C, and 11K are transferred onto the intermediate transfer belt 2 so as to be sequentially superimposed. In this embodiment, each image forming unit S constitutes a toner image forming unit that forms a toner image on the intermediate transfer belt 2.

  The toner image formed on the intermediate transfer belt 2 is conveyed by being sandwiched between the intermediate transfer belt 2 and the secondary transfer roller 17 by the action of the secondary transfer roller 17 in the secondary transfer portion N2. Is transferred onto the transfer material P (secondary transfer). At this time, the secondary transfer roller 17 is applied with a secondary transfer voltage (secondary transfer bias), which is a DC voltage having a polarity (positive in this embodiment) opposite to the charging polarity of the toner during development. For example, when a full-color image is formed, a multiple toner image formed in a state where four color toners are superimposed on the intermediate transfer belt 2 is transported by the intermediate transfer belt 2 and moved to the secondary transfer portion N2. At the next transfer portion N2, the images are transferred onto the transfer material P all at once. The transfer material P is fed from the transfer material cassette 21 or the like by the feed roller 22 or the like in the feeding / conveying device 20, and then the secondary transfer portion N2 by the registration roller 23 in synchronization with the toner image on the intermediate transfer belt 2. It is conveyed to.

  The transfer material P onto which the toner image has been transferred is conveyed to the fixing device 19 and heated and pressed at a fixing nip portion between the fixing roller 19a and the pressure roller 19b included in the fixing device 19. As a result, the toner image is fixed on the surface of the transfer material P. Thereafter, the transfer material P is discharged (output) to the outside of the apparatus main body 110 of the image forming apparatus 100.

  On the other hand, toner (primary transfer residual toner) remaining on the photosensitive drum 11 after the primary transfer process is removed from the photosensitive drum 1 by the drum cleaning device 16 and collected. The drum cleaning device 16 scrapes and removes toner from the surface of the rotating photosensitive drum 11 with a cleaning blade as a cleaning member. Further, the toner (secondary transfer residual toner) remaining on the intermediate transfer belt 2 after the secondary transfer step is removed from the intermediate transfer belt 2 by the belt cleaning device 18 and collected. The belt cleaning device 18 scrapes and removes toner from the surface of the rotating intermediate transfer belt 2 with a cleaning blade as a cleaning member. The removed toner passes through a collected toner conveyance path (not shown) and is collected into a collected toner container (not shown).

2. Intermediate Transfer Belt Unit Next, the intermediate transfer belt unit 1 in this embodiment will be further described. For the image forming apparatus 100 and its elements, the front side in FIG. 1 is referred to as “front side”, and the back side in FIG. 1 is referred to as “back side”. The depth direction connecting the front side and the back side is substantially parallel to the rotation axis direction (longitudinal direction) of the photosensitive drum 11 and the stretching rollers 3, 4, and 5 of the intermediate transfer belt 2.

  In this embodiment, the intermediate transfer belt unit 1 can be attached to and detached from the apparatus main body 110 of the image forming apparatus 100. FIG. 2 is a perspective view of the intermediate transfer belt unit 1.

  The intermediate transfer belt unit 1 has an intermediate transfer belt 2 (in FIG. 2, a part of the front side is notched). Further, the intermediate transfer belt unit 1 includes a driving roller 3, a driven roller 4, and a tension roller 5 as a plurality of stretching rollers around which the intermediate transfer belt 2 is wound. The driving roller 3, the driven roller 4 and the tension roller 5 are attached to a frame (main frame) 31.

  The drive roller 3 is rotatably supported by drive roller bearing members 32 (only the front side is shown in FIG. 2) at both end sides in the rotation axis direction. The drive roller bearing member 32 is attached to the frame 31. Then, the driving roller 3 is rotated by driving transmitted from the driving means (not shown) to the driving coupling 33. When the driving roller 3 is driven to rotate, the intermediate transfer belt 2 is conveyed. The surface of the drive roller 3 is formed of a rubber layer having a high friction coefficient so as to convey the intermediate transfer belt 2 without slipping.

  The driven roller 4 is rotatably supported by a driven roller bearing member 34 (only the front side is shown in FIG. 2) at both ends in the rotational axis direction. The driven roller bearing member 34 is attached to the frame 31. The driven roller 4 rotates following the intermediate transfer belt 2.

  The tension roller 5 is rotatably supported by a tension roller bearing member 35 on both end sides in the rotation axis direction. The tension roller bearing member 35 is attached to the frame 31 so as to be movable (slidable). Both tension roller bearing members 35 are urged by a compression force of a tension spring 36 (FIG. 4) constituted by a compression spring as urging means. The tension roller bearing member 35 is moved (slid) from the inner peripheral surface side to the outer peripheral surface side of the intermediate transfer belt 2 along the biasing direction by the tension spring 36. Accordingly, the tension roller 5 urges the intermediate transfer belt 2 from the inner peripheral surface side to the outer peripheral surface side of the intermediate transfer belt 2 to apply tension to the intermediate transfer belt 2.

  FIG. 3 is a schematic perspective view showing a cross section of an end portion on the back side of the intermediate transfer belt 2. 3 shows only the end portion on the back side, but in the present embodiment, the end portion on the front side has the same configuration (symmetric with respect to the center in the width direction of the intermediate transfer belt 2). In this embodiment, ribs (protruding members) 6 that protrude from the inner peripheral surface 2 a are provided on the inner peripheral surface 2 a at both ends in the width direction of the intermediate transfer belt 2. In this embodiment, the rib 6 is a belt-like member having a substantially rectangular cross section substantially parallel to the width direction of the intermediate transfer belt 2, and is attached to substantially the entire circumference of the inner peripheral surface 2 a of the intermediate transfer belt 2. In this embodiment, a reinforcing tape (reinforcing member) 7 is provided on the outer peripheral surface 2 b at both ends in the width direction of the intermediate transfer belt 2. In this embodiment, the reinforcing tape 7 is attached to substantially the entire circumference of the outer peripheral surface 2 b of the intermediate transfer belt 2. In the present embodiment, the rib 6 and the reinforcing tape 7 are respectively disposed slightly inside the edges of the both ends of the intermediate transfer belt 2. In this embodiment, the rib 6 and the reinforcing tape 7 overlap each other in the width direction of the intermediate transfer belt 2 (particularly, in this embodiment, the area of the rib 6 exists in the area of the reinforcing tape 7). Is included). In this embodiment, the intermediate transfer belt 2 is formed of a material mainly composed of polyimide resin. In the present embodiment, the rib 6 is made of a material mainly composed of urethane rubber. In this embodiment, the reinforcing tape 7 is made of the same material as that of the intermediate transfer belt 2. The materials of the intermediate transfer belt 2, the rib 6, and the reinforcing tape 7 are not particularly limited.

  FIG. 4 is an enlarged perspective view showing the vicinity of the end of the tension roller 5 on the back side. Collars 8 as restricting members that can come into contact with the ribs 6 are provided at both ends of the tension roller 5 in the rotation axis direction. The collar 8 is rotatably attached to a rotation shaft 5 a extending at both ends of the tension roller 5 in the rotation axis direction. The collar 8 is disposed in a region overlapping the moving range of the rib 6 and the reinforcing tape 7 in the width direction of the intermediate transfer belt 2. The color 8 will be described in detail later. In this embodiment, a blade-type belt cleaning device 18 is provided at a position facing the tension roller 5 with the intermediate transfer belt 2 interposed therebetween.

  FIG. 5 is a cross-sectional view of the vicinity of the belt cleaning device 18 and the tension roller 5. The belt cleaning device 18 has a cleaning blade 18a as a cleaning member. The cleaning blade 18 a is in contact with the outer peripheral surface of the intermediate transfer belt 2 in the counter direction (so that the free end faces the upstream side in the conveyance direction of the intermediate transfer belt 2). The cleaning blade 18a is pressed toward the tension roller 5 via the intermediate transfer belt 2 by a compression spring 18c with the blade support shaft 18b as the center. Around the cleaning blade 18a, an upstream squeeze sheet 18d is disposed upstream of the cleaning blade 18a and a downstream squeeze sheet 18e is disposed downstream of the cleaning blade 18a in the conveying direction of the intermediate transfer belt 2. End seals 18f for preventing toner leakage from the belt cleaning device 18 are disposed at both ends of the cleaning blade 18a in the rotation axis direction. Further, the belt cleaning device 18 has a conveying screw 18g.

  The cleaning blade 18a, blade support shaft 18b, compression spring 18c, upstream and downstream squeeze sheets 18d and 18e, end seal 18f, and conveying screw 18g are attached to a cleaning container 18h. The toner scraped off from the outer peripheral surface of the intermediate transfer belt 2 by the cleaning blade 18a and collected in the cleaning container 18h is carried out of the belt cleaning device 18 by the conveying screw 18g.

  As will be described in detail later, the end seal 18 f as a pressing member presses the intermediate transfer belt 2 toward the tension roller 5 in a region overlapping the collar 8 in the rotation axis direction of the tension roller 5. Further, in the width direction of the intermediate transfer belt 2, the region where the end seal 18 f presses the intermediate transfer belt 2 overlaps the moving range of the rib 6 and the reinforcing tape 7.

3. Next, the collar 8 as the restricting member in the present embodiment will be described in more detail. FIG. 6 is a perspective view of the collar 8. In this embodiment, the collars 8 disposed at both ends of the tension roller 5 in the rotation axis direction have the same configuration (symmetric with respect to the center of the tension roller 5 in the rotation axis direction).

  The collar 8 comes into contact with the rib 6 to restrict the movement of the tension roller 5 in the rotational axis direction of the tension roller 5 of the rib 6, and contacts the rib 6 to the inside of the rib 6 in the radial direction of the tension roller 5. A second restricting surface 8b for restricting the movement of the second member. In the present embodiment, the first restricting surface 8 a is a tapered surface inclined with respect to the rotation axis of the tension roller 5 (an extension of the outer peripheral surface of the tension roller 5). In the present embodiment, the second restricting surface 8 b is a surface along the inner peripheral surface 6 a of the rib 6. In particular, in the present embodiment, the second restricting surface 8b is a cylindrical surface that is substantially parallel to the rotation axis of the tension roller 5 (an extension of the outer peripheral surface of the tension roller 5). In the present embodiment, the first restriction surface 8a is disposed closer to the center side in the width direction of the intermediate transfer belt 2 than the second restriction surface 8b. That is, in the present embodiment, the first regulating surface 8a gradually increases in diameter from the widthwise end portion side of the intermediate transfer belt 2 to the widthwise center side of the intermediate transfer belt 2 and substantially the same as the tension roller 5. It is a concentric taper surface. In the present embodiment, the second restricting surface 8 b is a cylindrical surface having a diameter smaller than the outer diameter of the tension roller 5 and substantially concentric with the tension roller 5. The first restricting surface 8a is an edge portion 6c (FIG. 3) formed by an inner peripheral surface 6a (FIG. 3) of the rib 6 and a side surface 6b (FIG. 3) intersecting the inner peripheral surface 6a of the rib 6. Or at least one of the side surfaces 6b. The second restriction surface 8 b is in contact with the inner peripheral surface 6 a of the rib 6. In this embodiment, the collar 8 is supported so as to be rotatable relative to the tension roller 5. The outer peripheral surface of the tension roller 5 and the outer diameter of the tension roller 5 refer to the main portion of the tension roller 5, that is, the portion around which the intermediate transfer belt 2 is wound. This will be described in more detail below.

  In the present embodiment, the collar 8 is a substantially cylindrical member having a step as a whole, in which a relatively large-diameter first portion 81 and a relatively small-diameter second portion 82 are integrally formed. It is. The collar 8 is rotatably attached to the rotation shaft 5a by inserting the rotation shaft 5a of the tension roller 5 through the central support hole 8c. In this embodiment, the first portion 81 is disposed on the center side in the width direction of the intermediate transfer belt 2 (the center side in the rotation axis direction of the tension roller 5), and the second portion 82 is an end in the width direction of the intermediate transfer belt 2. It is arranged on the part side (end part side in the rotation axis direction of the tension roller 5). The first portion 81 is formed with a first restricting surface 8a having a tapered surface so that the diameter of the first portion 81 gradually increases from the connecting portion between the first portion 81 and the second portion 82 along the rotation axis of the collar 8. Has been. Further, the outer peripheral surface of the second portion 82 forms a second restricting surface 8b which is a cylindrical surface. In this embodiment, the collar 8 is formed using a sliding grade of POM as a material. The material of the collar 8 is not particularly limited.

  The first regulating surface 8a is a tapered surface (slope) having an angle α (FIG. 7) with respect to the rotation axis of the tension roller 5 of 60 °. Note that the angle α of the tapered surface is not limited to this, and is typically 30 ° or more and less than 90 °, preferably 45 ° or more and 75 ° or less. The first restricting surface 8a having a relatively low coefficient of friction suppresses the rib 6 from climbing onto the tension roller 5 and restricts the belt side of the intermediate transfer belt 2. In the present embodiment, the maximum diameter of the first regulating surface 8a is substantially the same as the outer diameter of the tension roller 5, and the minimum diameter is substantially the same as the outer diameter of the second regulating surface 8b.

  The second restricting surface 8 b is a cylindrical surface that is substantially concentric with the tension roller 5. The outer diameter of the second restricting surface 8b is substantially the same as the inner diameter of the rib 6 (the diameter of a circle inscribed in the inner peripheral surface of the rib 6 at the position of the intermediate transfer belt 2 wound around the tension roller 5) or the rib. It is smaller than the inner diameter of 6. Considering the tolerance of the rib 6 and the collar 8, it is preferable that the outer diameter of the second restricting surface 8b is slightly smaller than the inner diameter of the rib 6, for example, about 1.0 mm. The second restricting surface 8 b is a surface along the inner peripheral surface 6 a of the rib 6 in order to keep the rib 6 substantially parallel to the rotation axis of the tension roller 5. In this embodiment, the inner peripheral surface 6 a of the rib 6 is a surface substantially parallel to the rotation axis of the tension roller 5, so the second restricting surface 8 b is the rotation axis of the tension roller 5 (the intermediate transfer belt 2 of the intermediate transfer belt 2). It is preferable to be substantially parallel to the plane. However, the second restricting surface 8b may have an inclination of about 1.3 ° with respect to the rotation axis of the tension roller 5 due to a fitting tolerance between the collar 8 and the rotation shaft 5a of the tension roller 5. . Here, the case where the inclination is approximately equal to the tolerance is included in the case of being substantially parallel.

  FIG. 7 is a side view showing the positional relationship in the width direction of the intermediate transfer belt 2 of each member in the vicinity of the back end of the tension roller 5. In FIG. 7, the intermediate transfer belt 2 and the reinforcing tape 7 are not shown. In the width direction of the intermediate transfer belt 2, the tension roller 5 is longer on the end side than the cleaning blade 18 a of the belt cleaning device 18. Thereby, a better cleaning performance of the intermediate transfer belt 2 by the cleaning blade 18a can be obtained. A collar 8 is attached to an end of the tension roller 5 in the rotation axis direction, and a rib 6 is disposed at a position of the second restriction surface 8 b of the collar 8. In the present embodiment, the intermediate transfer belt 2 moves in the width direction by ± 0.6 mm depending on the belt, and by ± 0.3 mm by play between the rotary shaft 5 a of the tension roller 5 and the tension roller bearing member 35. Therefore, in the present embodiment, the second restriction surface 8 b has a length in the width direction of the intermediate transfer belt 2 that is about 1 mm longer than the rib 6.

  The end seal 18 f of the belt cleaning device 18 covers an area from the end of the cleaning blade 18 a to at least a part of the rib 6 in the width direction of the intermediate transfer belt 2 regardless of the belt of the intermediate transfer belt 2. It is attached as follows. As a result, toner leakage from the belt cleaning device 18 can be better prevented. In this embodiment, the reinforcing tape 7 is provided in a region including the ribs 8 in the width direction of the intermediate transfer belt 2. Therefore, the end seal 18f is attached so as to cover the region from the end of the cleaning blade 18a to at least a part of the reinforcing tape 7 in the width direction of the intermediate transfer belt 2 regardless of the belt of the intermediate transfer belt 2. ing. As described above, in this embodiment, the pressing member that presses the intermediate transfer belt 2 toward the tension roller 5 is disposed in a region overlapping the collar 8 in the rotation axis direction of the tension roller 5. In this embodiment, this pressing member is a sealing member (provided in a belt cleaning device 18 that removes deposits from the surface of the intermediate transfer belt 2 disposed opposite to the tension roller 5 via the intermediate transfer belt 2). End seal) 18f.

  FIG. 8 is a diagram schematically showing the behavior of the intermediate transfer belt 2 in the present embodiment (FIG. 8A) and the comparative example (FIG. 8B).

  FIG. 8B is a schematic diagram of the case where the collar 8 is not provided with the second restricting surface 8b (comparative example). At the end of the tension roller 5, there is a regulating surface 8a which is a tapered surface of the collar 8, and the rib 6 is regulated. The portion of the rib 6 is pressed toward the tension roller 5 by the end seal 18 f of the belt cleaning device 18, so that the intermediate transfer belt 2 is bent inward in the radial direction of the tension roller 5. If the intermediate transfer belt 2 is conveyed in this state, the bent portion may be fatigued due to stress concentration, and cracks may occur, causing damage to the intermediate transfer belt 2. This phenomenon becomes more prominent when the intermediate transfer belt 2 is thinned or the hardness is increased by applying a coating agent on the surface of the intermediate transfer belt 2.

  On the other hand, FIG. 8A is a schematic diagram when the collar 8 is provided with the second restricting surface 8b (this embodiment). By having the second restricting surface 8b of the collar 8 below the rib 6 (in the radial direction of the tension roller 5), the posture of the rib 6 can be maintained substantially parallel to the rotation axis of the tension roller 5. it can. Therefore, even if the portion on the rib 6 is pressurized by the end seal 18f of the belt cleaning device 18, the bending of the intermediate transfer belt 2 is sufficiently suppressed. As described above, in this embodiment, the load applied to the end portion in the width direction of the intermediate transfer belt 2 is significantly reduced, and the breakage of the intermediate transfer belt 2 can be suppressed.

  In the present embodiment, as described above, the second regulating surface 8b is formed so as to be able to come into contact with the rib 6 regardless of the belt of the intermediate transfer belt 2, so that the belt of the intermediate belt 2 Regardless, the rib 6 does not fall off from the second restricting surface 8b.

  Further, in this embodiment, portions having different radii such as the inner peripheral surface 6 a of the rib 6 and the inner peripheral surface 2 a of the intermediate transfer belt 2 run coaxially in different regions in the width direction of the intermediate transfer belt 2. For this reason, when the collar 8 rotates integrally with the tension roller 5, the intermediate transfer belt 2 is twisted due to the difference in the peripheral speed between the above-described regions, which may affect the running of the intermediate transfer belt 2. is there. On the other hand, in this embodiment, the collar 8 is rotatably supported on the rotation shaft 5a of the tension roller 5, and the tension roller 5 and the collar 8 can rotate independently. The influence can be reduced.

  As described above, according to the present embodiment, the collar 8 is the second regulating surface which is a cylindrical surface along the inner peripheral surface 6 a of the rib 6 for keeping the rib 6 substantially parallel to the rotation axis of the tension roller 5. 8b. Thus, even if the intermediate transfer belt 2 is pushed inward in the radial direction of the tension roller 5 by the end seal 18f of the belt cleaning device 18 or other external force, the intermediate transfer belt 2 is bent at the end of the tension roller 5. Can be suppressed. Therefore, according to the present exemplary embodiment, it is possible to reduce the load applied to the end portion of the intermediate transfer belt 2 in the width direction, and to prevent the intermediate transfer belt 2 from being damaged. Further, by supporting the collar 8 so as to be rotatable relative to the tension roller 5, the influence on the running of the intermediate transfer belt 2 can be reduced.

[Example 2]
Next, another embodiment of the present invention will be described. The basic configurations and operations of the belt conveyance device and the image forming apparatus of the present embodiment are the same as those of the first embodiment. Therefore, in the belt conveyance device and the image forming apparatus of the present embodiment, elements having the same or corresponding functions or configurations as those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 9 is a side view of the collar 8 as a regulating member in the present embodiment (the rotating shaft 5a of the tension roller 5 is also shown). As shown in FIG. 9, in the present embodiment, the collar 8 includes a first portion 81 having a first restricting surface 8a and a second portion 82 having a second restricting surface 8b as separate bodies. Yes. Also in the present embodiment, as in the first embodiment, the first portion 81 and the second portion 82 are rotatably supported by the rotation shaft 5a of the tension roller 5, respectively.

  There is an advantage that the configuration can be simplified by integrating the first portion 81 and the second portion 82 as in the first embodiment. However, portions having different radii such as the inner peripheral surface 6 a of the rib 6, the side surface 6 b of the rib 6, and the inner peripheral surface 2 a of the intermediate transfer belt 2 run coaxially in different regions in the width direction of the intermediate transfer belt 2. For this reason, when the first portion 81 and the second portion 82 rotate together, the intermediate transfer belt 2 is caused to travel in a state where the peripheral speed difference is slightly different in each of the regions having different radii. As a result, the intermediate transfer belt 2 is twisted, which may affect the running performance of the intermediate transfer belt 2. In an extreme case, it is conceivable that the image is disturbed to cause color misregistration or that the intermediate transfer belt 2 is damaged due to shearing force. On the other hand, in the present embodiment, the first portion 81 and the second portion 82 are separated and can be rotated independently, so that the influence on the running performance of the intermediate transfer belt 2 can be reduced. it can.

  As described above, according to this embodiment, the same effects as those of the first embodiment can be obtained, and the first portion 81 and the second portion 82 of the collar 8 are separated from each other. The influence on the running can be further reduced.

[Others]
As mentioned above, although this invention was demonstrated according to the specific Example, this invention is not limited to the above-mentioned Example.

  In the above-described embodiment, the case where the first restriction surface of the restriction member is disposed closer to the center in the width direction of the belt than the second restriction surface has been described. The present invention typically works favorably in such a configuration, but as shown in the schematic diagram of FIG. 10, the first regulating surface is wider than the second regulating surface in the width direction of the belt. A configuration located on the end side of the can also be contemplated. In FIG. 10, elements having the same or corresponding functions or configurations as those of the above-described embodiment are denoted by the same reference numerals.

  Further, in the above-described embodiment, the rib is regulated by the regulating member at both ends in the rotation axis direction of the stretching roller, but is not limited thereto. Typically, such a configuration is preferable because it can cope with the belt in any direction of the belt. However, when it is known that the tendency toward the belt is one direction, the rib can be restricted by the restriction member only at one end portion in the rotation axis direction of the stretching roller.

  In the above-described embodiment, the stretching roller on which the regulating member is disposed at the end is a stretching roller other than the driving roller that drives the belt among the plurality of stretching rollers. In particular, in the above-described embodiment, the tension roller is a tension roller that applies tension to the belt. Such a configuration is preferable because the force applied to the belt is easily relaxed when the rib contacts the regulating member and the belt is returned, and the influence on the running of the belt is relatively small. However, the present invention is not limited to this, and the regulating member may be disposed at the end of at least one of the plurality of stretching rollers. The regulating member may be arranged at the end of two or more stretching rollers (or all stretching rollers) among the plurality of stretching rollers.

  In the above-described embodiments, the intermediate transfer type image forming apparatus including the belt conveyance device whose belt is an intermediate transfer member has been described as an example. However, the present invention is not limited to this. FIG. 11 is a schematic cross-sectional view of a main part of a direct transfer type image forming apparatus including a belt conveyance device in which a belt is a transfer material carrier. In FIG. 11, elements having the same or corresponding functions or configurations as those of the above-described embodiment are denoted by the same reference numerals. An image forming apparatus 100 in FIG. 11 has a transfer material carrying belt 102 constituted by an endless belt as a transfer material carrying body, instead of the intermediate transfer belt 2 in the image forming apparatus 100 in FIG. In the image forming apparatus 100 of FIG. 11, the toner image formed on the photosensitive drum 11 in each image forming unit S is transferred to the transfer material P carried and transported on the transfer material carrying belt 102 in each transfer unit N. Is done. Also in such a belt conveying device (transfer material carrying belt unit) 1 of the direct transfer type image forming apparatus 100, ribs are provided on the inner peripheral surface of the transfer material carrying belt 102, for example, regulating members at both ends of the tension roller 5. May be provided to regulate the belt. Therefore, also in this case, the same effect as that of the above-described embodiment can be obtained by applying the present invention. Similarly, the present invention can be applied to the case where the belt is a photosensitive belt or an electrostatic recording dielectric belt, and the same effects as those of the above-described embodiments can be obtained.

1 Intermediate transfer belt unit (belt transport device)
2 Intermediate transfer belt 5 Tension roller (stretching roller)
6 Rib 7 Reinforcement tape 8 Collar (Regulator)
8a First regulating surface (tapered surface)
8b Second regulating surface (cylindrical surface)
18 Belt cleaning device 18a Cleaning blade 18f End seal 81 First part 82 Second part

Claims (14)

An endless belt,
A rib provided on the inner peripheral surface of the end portion in the width direction of the belt;
A plurality of stretching rollers for stretching the belt;
A restricting member that can be in contact with the rib, disposed at an end in the rotational axis direction of at least one of the plurality of stretching rollers;
In a belt conveyance device having
The regulating member is in contact with the rib, a first regulating surface that regulates movement of the at least one stretching roller in the rotation axis direction of the rib, and the at least one of the rib in contact with the rib And a second restricting surface for restricting movement of the tension roller inward in the radial direction.   The belt conveying device according to claim 1, wherein the first restriction surface is a tapered surface inclined with respect to a rotation axis of the at least one stretching roller.   The belt conveying device according to claim 1, wherein the second restriction surface is a surface along an inner peripheral surface of the rib.   The belt conveying device according to any one of claims 1 to 3, wherein the second restriction surface is a cylindrical surface substantially parallel to a rotation axis of the at least one stretching roller.   5. The belt conveyance device according to claim 1, wherein the first restriction surface is disposed closer to a center side in the width direction of the belt than the second restriction surface. .   The first restricting surface is disposed closer to the center in the width direction of the belt than the second restricting surface, and the first restricting surface extends from the end side in the width direction of the belt. The taper surface is gradually tapered toward the center in the width direction and substantially concentric with the at least one stretching roller, and the second restriction surface is smaller in diameter than the outer diameter of the at least one stretching roller, The belt conveying device according to claim 1, wherein the belt conveying device is a cylindrical surface substantially concentric with the at least one stretching roller.   The belt conveying device according to claim 1, wherein the restricting member is rotatably supported relative to the at least one stretching roller.   The said restricting member WHEREIN: The 1st part which has the said 1st control surface, and the 2nd part which has the said 2nd control surface are made into a different body, The any one of Claims 1-7 characterized by the above-mentioned. The belt conveyance device according to claim 1.   The belt according to any one of claims 1 to 8, wherein the at least one stretching roller is a stretching roller other than a driving roller that drives the belt among the plurality of stretching rollers. Conveying device.   The pressing member that presses the belt toward the at least one stretching roller is disposed in a region that overlaps the restriction member in the rotation axis direction of the at least one stretching roller. The belt conveying apparatus as described in any one of Claims 9.   The pressing member is a seal member provided in a cleaning device that removes deposits from the surface of the belt disposed to face the at least one tension roller via the belt. Item 11. The belt conveyance device according to Item 10.   The belt conveyance device according to any one of claims 1 to 11, wherein a reinforcing member is provided on an outer peripheral surface of the belt in a region overlapping with the rib in the width direction of the belt.   The rib is provided at both ends in the width direction of the belt, and the restricting member is provided at both ends in the rotation axis direction of the at least one stretching roller. The belt conveyance device according to claim 1.   An image forming apparatus comprising: the belt conveyance device according to claim 1; and a toner image forming unit that forms a toner image on the belt or a transfer material carried on the belt.

Images