JP2014119531A - Belt driving device, belt transfer device, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a belt driving device including a belt deviation correction mechanism that requires a small number of components and can be installed in a small space.SOLUTION: A belt driving device has a deviation detection rotating body 101 that is provided laterally to a driven roller 17 and rotationally driven independent of the driven roller 17. The deviation detection rotating body 101 is rotated by friction force when an intermediate transfer belt 16 is brought close and into contact therewith. Since the deviation detection rotating body 101 has an outer shape center by which the deviation detection rotating body 101 is supported shifted from a shaft hole that supports the driven roller 17, when the deviation detection rotating body 101 is rotated, the driven roller 17 is displaced. Since the driven roller 17 can be displaced with a simple configuration, the belt driving device can be achieved including a belt deviation correction mechanism that requires a small number of components and can be installed in a small space.

Description

  The present invention relates to a belt driving device, a belt transfer device including the belt driving device, and an image forming apparatus.

  A transfer belt unit used in an electrophotographic image forming apparatus such as a belt driving device or a belt transfer device, for example, a copying machine, a printer, a facsimile, or a complex machine of these, requires a transfer belt offset mechanism. However, if the transfer belt has a large offset force, the transfer belt cannot be suppressed by the offset mechanism alone, and the transfer belt may be damaged. For this reason, belt misalignment correction techniques that reverse the belt misalignment direction and reduce the misalignment force of the transfer belt by twisting at least one of the rollers that suspend the transfer belt are already known.

  In Patent Document 1, for the purpose of controlling the shift of the belt, a shift detection rotating body that is provided on the side of the roller and is rotated independently of the roller, and an engagement that is rotationally displaced by the rotation of the shift detection rotating body. A member, and a shift restricting member with which the engaging member can be engaged. The roller comes into contact with the shift detecting rotating body, the shift detecting rotating body is rotated, and the engaging member engages with the shift restricting member. Is disclosed that is displaced in a direction perpendicular to its axial direction.

  However, the conventional belt misalignment correction technique has a problem that the mechanism is complicated, the number of parts is increased, a large space is required for the mechanism, and the cost and size are increased.

  SUMMARY OF THE INVENTION An object of the present invention is to realize a belt driving device having a space saving belt deviation correction mechanism with a small number of parts, a belt transfer device having the belt driving device, and an image forming apparatus having the belt transfer device. And

  The belt driving device of the present invention includes an endless belt and a plurality of rollers wound around the endless belt so that the endless belt can travel. The plurality of rollers includes a roller whose at least one end can be displaced. A supporting member to be supported; a shift detection rotating body that is driven to rotate by the endless belt independently of the displaceable roller; and a bearing that supports the shift detection rotating body at at least one end of the displaceable roller; The center of the outer shape of the deviation detecting rotating body supported by the bearing is shifted from the axis of the shaft hole that supports the displaceable roller, and the rotation of the deviation detecting rotating body It has the structure which can displace the displaceable roller.

  According to the present invention, the shift detection rotating body shifts the shaft hole of the outer shape supporting the shift detection rotating body from the shaft hole that supports the driven roller, so that the driven roller is displaced when the shift detection rotating body rotates. Since the driven roller can be displaced with such a simple configuration, a space-saving belt deviation correction mechanism can be realized with a small number of parts.

1 is a schematic configuration diagram illustrating an example of a printer as an image forming apparatus that is an object of the present invention. The perspective view which shows the tension structure of an intermediate transfer belt Illustration for explaining belt-side restrictions Side cross-sectional view for explaining the tension structure of the intermediate transfer belt Sectional view (A) for explaining the structure of the intermediate transfer belt misalignment correction mechanism and a view seen from the right (B) FIG. 5A is a diagram corresponding to FIG. 5A for explaining the operation of the intermediate transfer belt shift correction mechanism. Figure corresponding to Fig. 5 (B) The figure explaining another embodiment of the deviation correction mechanism of an intermediate transfer belt The figure explaining the transfer device of another system

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In the belt driving apparatus according to the present embodiment, the belt deviation correction mechanism has the following characteristics. In short, the belt deviation correction mechanism provided in the belt driving device according to the present embodiment is provided on the side of the driven roller, and the deviation detection rotating body that rotates independently from the driven roller detects the deviation due to the belt being offset. When it comes into contact with the rotating body, the offset detecting rotating body is rotated by frictional force. The deviation detecting rotator is offset from the shaft hole that supports the driven roller and the outer shaft that supports the deviation detecting rotator. Therefore, the driven roller is displaced when the shift detection rotating body rotates.

  The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a printer, a facsimile machine, and a multifunction machine of these, and a belt driving device of a belt transfer device used therefor. However, the present invention is limited to the illustrated embodiment. Not. In the following description, an intermediate transfer type transfer apparatus will be described, but the present invention can also be adopted in a direct transfer type transfer apparatus.

<Embodiment 1>
FIG. 1 is a schematic configuration diagram illustrating an example of a printer as an image forming apparatus that is an object of the present invention.
The illustrated image forming apparatus includes four process units 1K, 1Y, 1M, and 1C for forming images with developers of black, yellow, magenta, and cyan corresponding to color separation components of a color image. .

  Each process unit 1K, 1Y, 1M, and 1C includes toner bottles 6K, 6Y, 6M, and 6C that store unused toners of different colors. Other than that, the configuration is the same. The structure of one process unit 1K will be described as an example. The process unit 1K includes a photosensitive drum 2K, a drum cleaning device 3K, a charging device 4K, a developing device 5K, and the like.

  An exposure unit 7 is disposed above each process unit 1K, 1Y, 1M, 1C. The exposure device 7 is configured to emit laser light from a laser diode based on image data.

  A transfer device 15 is disposed below each process unit 1K, 1Y, 1M, and 1C. The transfer device 15 is driven by four primary transfer rollers 19K, 19Y, 19M, and 19C, which are opposed to the photosensitive drums 2K, 2Y, 2M, and 2C, which are image carriers, and the primary transfer rollers 19K, 19Y, 19M, and 19C, respectively. It has an intermediate transfer belt 16 that can be circulated around a roller 18 and a driven roller 17, a secondary transfer roller 20, a belt cleaning device 21, a cleaning backup roller 22, and the like that are disposed to face the driving roller 18.

  In the lower part of the image forming apparatus, there are provided a paper feed cassette 30 capable of storing a large number of paper P and a paper feed roller 30 a for sending the paper P from the paper feed cassette 30 toward the paper feed path 31. Near the end of the paper feed path 31, a registration roller pair 32 is provided for temporarily stopping the paper.

  A post-transfer conveyance path 33 is disposed above the nip between the secondary transfer roller 20 and the driving roller 18. A fixing device 34 is provided near the end of the post-transfer conveyance path 33. The fixing device 34 includes a fixing roller 34a that includes a heat source such as a halogen lamp (not shown), and a pressure roller 34b that rotates while contacting the fixing roller 34a with a predetermined pressure.

  A post-fixing conveyance path 35 is disposed above the fixing device 34, and branches to a paper discharge path 36 and a reverse conveyance path 41 at the end of the post-fixing conveyance path 35. A switching member 42 that swings around a swing shaft 42a is disposed on the side of the post-fixing conveyance path 35. A paper discharge roller pair 37 is disposed at the end of the paper discharge path 36. The reverse conveyance path 41 joins the paper feed path 31 at the end thereof, and a reverse conveyance roller pair 43 is disposed in the middle of the reverse conveyance path 41. A paper discharge tray 44 having an upper cover recessed inward is disposed at the top of the image forming apparatus.

An image forming operation in the image forming apparatus configured as described above will be briefly described.
The photosensitive drum 2 of the process unit 1 is rotationally driven in the clockwise direction in the figure by driving means (not shown), and the surface of the photosensitive drum 2 is uniformly charged to a predetermined polarity by the charging roller 4. The charged photoreceptor surface is irradiated with laser light from the exposure unit 7. As a result, an electrostatic latent image is formed on the surface of the photosensitive drum 2. At this time, the image information exposed on each photosensitive drum 2 is single-color image information obtained by separating a desired full-color image into color information of yellow, magenta, cyan, and black. Each color toner is applied from the developing device 5 to the electrostatic latent image formed in this manner, and visualized as a toner image.

  Further, the intermediate transfer belt 16 is driven to run counterclockwise in the drawing, and the toner images of the respective colors are sequentially transferred from the photosensitive drum 2 to the intermediate transfer belt 16 by the action of the primary transfer roller 19 in each process unit 1. In this way, the intermediate transfer belt 16 carries a full-color toner image on its surface.

  Note that any one of the process units 1 can be used to form a single-color image or a two-color or three-color image. In the case of monochrome printing, image formation is performed using the Bk unit among the four process units 1. The residual toner adhering to the surface of the photosensitive drum 2 after the toner image is transferred is removed from the surface of the photosensitive drum 2 by the belt cleaning device 21 to prepare for the next image formation.

  On the other hand, the sheet is fed from the sheet feeding cassette 30 and is sent toward the secondary transfer position by the registration roller pair 32 in timing with the toner image carried on the intermediate transfer belt 16. In this example, a transfer voltage having a polarity opposite to the toner charging polarity of the toner image on the surface of the intermediate transfer belt is applied to the secondary transfer roller 20, whereby the toner image on the surface of the intermediate transfer belt is collectively transferred onto the sheet. . When the sheet on which the toner image has been transferred passes through the fixing device 34, the toner image is melted and fixed on the sheet by heat and pressure. The fixed sheet is discharged by a discharge roller 37 to a discharge tray 44 formed on the upper surface of the apparatus main body.

  When printing on both sides of the sheet, the sheet having the toner image fixed on one side of the sheet is fed back to the reverse conveyance path 41 by switching the sheet by reversely rotating the paper discharge roller 24 as described above. Is reversed and the sheet is fed again to the registration roller 32. The toner image is transferred from the intermediate transfer belt 16 to the back side of the re-feeded paper, and the back side image is fixed by the fixing device 34, whereby the paper carrying the images on both the front and back sides is discharged to the paper discharge tray 44. This completes double-sided printing.

2 and 3 are diagrams for explaining the principle for regulating the belt shift.
A driving roller 18 as a plurality of rollers including an intermediate transfer belt 16 that is a flat belt having a relatively wide belt width as a traveling endless belt, and a roller 17 that is capable of displacing the both ends of the intermediate transfer belt 16. And a driven roller 17. The driving roller 18 is integrally formed with the shaft 18a, and the displaceable roller 17 is integrally formed with the shaft 17a. The driving roller 18 and the displaceable roller 17 are rotatably supported by the shafts 18a and 17a, respectively. Has been.

  For some reason, it is assumed that the intermediate transfer belt 16 approaches the z2 direction in the axial direction of the driving roller 18 and the displaceable roller 17. In this case, in order to give the intermediate transfer belt 16 an action of returning to the original position, the distance between the axes of the rollers 17 and 18 that have approached may be made larger than the distance between the other axes. For this purpose, as shown in FIG. 3, the end of the displaceable roller 17 on which the deviation occurs is a direction perpendicular to the axial direction of the displaceable roller 17 and the drive roller 18 and the displaceable roller 17 are If the intermediate transfer belt 16 is displaced so as to be located on non-planar surfaces, the intermediate transfer belt 16 returns to the original return direction z1. The deviation of the intermediate transfer belt 16 is surely generated even if the roller 17 that can be displaced with respect to the driving roller 18 is slightly twisted.

FIG. 4 is a diagram for explaining a stretch configuration of the intermediate transfer belt.
The intermediate transfer belt 16 is stretched by a driving roller 18 and a displaceable driven roller (tension roller) 17, and the driven roller 17 serves as a tension roller that applies tension to the intermediate transfer belt 16. The driving roller 18 is rotatably supported by the intermediate transfer unit side plate 50. The driving roller 18 receives driving force from a driving source (not shown) and rotates counterclockwise to drive the intermediate transfer belt 16. The driven roller 17 is rotatably supported by the tension arm 51, and applies tension to the intermediate transfer belt 16 by pressing the tension arm 51 with a tension spring 52.

FIG. 5 is a diagram for explaining the configuration of a specific offset correction mechanism for the intermediate transfer belt.
The driven roller 17 is rotatably supported by a shift detection rotating body by a shaft 17a, and the shift detection rotating body 101 is rotatable independently of the displaceable driven roller 17, and the shift detection rotating body is supported by a bearing 102. It is supported rotatably. The bearing 102 is supported by the tension arm 51.

  In the deviation detecting rotating body, the center of the hole supported by the shaft 17a of the driven roller 17 and the center of the outer shape supported by the bearing 102 are intentionally eccentric by δ. The shift detection rotating body 101 is always urged by the torsion coil spring 103 in the direction of arrow a in FIG. Further, in order to regulate the rotation range of the deviation detecting rotator 101, the deviation detecting rotator 101 is provided with a rotation restricting rib 101a, and the bearing 102 is provided with a step as a shape portion for receiving the rotation restricting rib 101a.

  In a state where the intermediate transfer belt 16 is not in contact with the shift detection rotating body 101, the rotation of the shift detection rotating body is restricted at a predetermined position as shown in FIG. 5B, and the shaft 17a of the driven roller 17 is supported. The center of the hole to be formed is almost directly below the center of the outer shape supported by the bearing 102.

6 and 7 are diagrams for explaining the operation of the deviation correction mechanism for the intermediate transfer belt.
When the intermediate transfer belt 16 approaches the arrow z2 direction in FIG. 6, the end surface of the intermediate transfer belt 16 comes into contact with the deviation detection rotating body 101, and the deviation detection rotation is caused to rotate 101 in the arrow b direction in FIG. . In the deviation detecting rotating body, the center of the hole supported by the shaft 17a of the driven roller 17 and the center of the outer shape supported by the bearing 102 are intentionally decentered. Is displaced by 2δ in the direction of the arrow x1 in FIG.

  Further, as shown in FIG. 6, the rotation of the shift detection rotating body is restricted at a predetermined position, and the center of the hole supported by the shaft 17 a of the driven roller 17 is substantially directly above the center of the outer shape supported by the bearing 102. . As shown in FIG. 3, the drive roller 18 and the driven roller 17 are displaced so as to be located on a non-planar direction in a direction perpendicular to the axial direction of the driven roller 17. Close to the return direction z1. When the intermediate transfer belt 16 is separated from the shift detection rotating body 101, the shift detection rotating body 101 returns to the original position shown in FIG. 5A by the biasing force of the torsion coil spring.

  Further, the deviation detecting rotator 101 is provided only at one end of the driven roller 17 and urges the driven roller 17 to be displaced in the direction of the arrow x2 in a state where the intermediate transfer belt 16 is not in contact with the deviation detecting rotator 101. Thus, the intermediate transfer belt 16 may be moved closer to the side where the shift detection rotating body 101 is present. By providing the shift correction mechanism only at one end, the number of parts can be reduced, and the space and cost can be reduced. In this case, it is desirable that the amount of displacement of the displaceable roller in the direction of the arrow x2 in a state where the belt is not in contact with the detection rotating body is 2δ or less. When the displacement amount is 2δ or more, even if the driven roller 17 is displaced, it is not possible to obtain a force for the intermediate transfer belt 16 to move in the z1 direction.

  Further, when the intermediate transfer belt 16 is easily moved in one direction as described above, the positional relationship with other members (mainly photosensitive drums) that are in contact with the intermediate transfer belt 16 and the flatness of holding the transfer device 15. Considering the installation state of the main body, the force of the belt in one direction must be increased to some extent. For this reason, it is necessary to increase the displacement of the driven roller 17 by increasing the amount of displacement when the intermediate transfer belt 16 is not in contact with the detecting roller 101. However, it is also necessary to increase the amount δ of shifting the shaft hole that supports the driven roller 17 of the shift detection rotator 101 and the outer shape shaft core that supports the shift detection rotator 101, which requires more space. . Therefore, it is better to provide the shift detection rotating body 101 at both ends of the driven roller 17. As a result, there is an effect that the space can be saved and the reliability can be improved.

<Embodiment 2>
FIG. 8 is a diagram for explaining another embodiment of the deviation correction mechanism for the intermediate transfer belt.
A taper portion 101b that widens from the center side of the driven roller 17 that is a displaceable roller to the bearing 102 side is provided on the shift detection rotating body 101, and when the intermediate transfer belt 16 approaches, the shift detection rotation with the intermediate transfer belt 16 is detected. The contact area with the body 101 is increased. Accordingly, the driving force received by the shift detection rotating body 101 from the intermediate transfer belt 16 can be increased, and the shift detection rotating body 101 can be reliably rotated.

<Embodiment 3>
FIG. 9 is a diagram for explaining another type of transfer device. In the above description, the driven roller 17 also functions as a tension roller that stretches the intermediate transfer belt 16. As shown in FIG. 9, the tension roller 53 may be provided separately, and the driven roller 17 may be rotatably supported on the intermediate transfer unit side plate 50.

  As described above, in the belt driving device according to the embodiment of the present invention, a traveling endless belt is stretched, and a plurality of rollers including a roller that can displace at least one end of its shaft are supported. At least one end of the support member, the displaceable roller has a shift detection rotating body that is driven to rotate by the endless belt independently of the displaceable roller, and a bearing that supports the shift detection rotating body. Since the deviation detecting rotator is displaced from the shaft hole that supports the displaceable roller and the outer shaft that supports the deviation detecting rotator, the displaceable roller is displaced when the deviation detecting rotator rotates. The deviation detecting rotator is provided with a rib for restricting the rotation range of the deviation detecting rotator, and a bearing that supports the deviation detecting rotator is provided with a shape for receiving the rib. By providing a mechanism for restricting the rotation range of the shift detection rotating body in the shift detection rotating body and the bearing that supports the shift detection rotating body, the number of parts can be reduced, and space and cost can be reduced.

  By providing a taper section on the offset detection rotating body and increasing the contact area between the endless belt and the offset detection rotating body, the force that the endless belt drives the offset detection rotating body increases, and the offset detection rotating body rotates stably. can do. The shift detection rotating body is provided only at one end of the displaceable roller, and the displaceable roller is already displaced in a state where the endless belt is not in contact with the shift detection rotating body, so that the endless belt approaches the side where the shift detection rotating body is located. Configure as follows. Then, by providing the shift correction mechanism only at one end, the number of parts can be reduced, and the space and cost can be reduced.

  In addition, the amount of shift between the shaft hole that supports the displaceable roller of the shift detection rotating body and the outer shape shaft core that supports the shift detection rotating body is such that the endless belt is not in contact with the shift detection rotating body. The amount of displacement of the displaceable roller is preferably 2 times or less. If the amount of displacement of the displaceable roller due to rotation of the deviation detecting rotator is not greater than the amount of displacement of the displaceable roller when the endless belt is not in contact with the deviation detecting rotator, the endless belt will deviate. This is because it cannot be moved away from the detection rotating body, but if the displacement amount is too large, even if the displaceable roller is displaced, it is not possible to obtain a force for the endless belt to move toward the end portion where the displacement amount is small.

  The shift detection rotating body may be provided at both ends of the displaceable roller, and the displaceable roller may not be displaced when the endless belt is not in contact with the shift detection rotating body. If the endless belt is configured to easily move in one direction, the endless belt is in one direction taking into account the positional relationship with other members that abut the endless belt, the flatness holding the unit including the endless belt, the installation state of the main body, etc. We must increase the power to approach. For this reason, it is necessary to increase the displacement of the endless belt by increasing the amount of displacement of the displaceable roller when the endless belt is not in contact with the detection rotating body. However, it is also necessary to increase the amount of displacement between the shaft hole that supports the displaceable roller of the shift detection rotator and the outer-shaped shaft core that supports the shift detection rotator, which requires more space. Therefore, it is more space-saving and the reliability can be improved by providing the shift detection rotating body at both ends of the displaceable roller and not displacing the displaceable roller when the endless belt is not in contact with the shift detection rotating body. .

  The present invention is not limited to the embodiments described above, and many variations are possible by those having ordinary knowledge in the art within the technical idea of the present invention.

1: Process unit 2: Photoconductor drum 3K: Drum cleaning device 4: Charging roller 4K: Charging device 5: Developing device 5K: Developing device 6K: Toner bottle 7: Exposure device 15: Transfer device 16: Intermediate transfer belt 17: Driven Roller 17a: Shaft 18: Drive roller 18a: Shaft 19: Primary transfer roller 20: Secondary transfer roller 21: Belt cleaning device 22: Cleaning backup roller 24: Paper discharge roller 30: Paper feed cassette 30a: Paper feed roller 31: Feed Paper path 32: Registration roller 33: Post-transfer conveyance path 34: Fixing device 34a: Fixing roller 34b: Pressure roller 35: Post-fixation conveyance path 36: Paper discharge path 37: Paper discharge roller 41: Reverse conveyance path 42: Switching member 42a: swinging shaft 44: discharge tray 50: intermediate transfer unit side plate 51: tension arm 52: Tension spring 53: Tension roller 101: Detection rotating body 101a: Rotation restricting rib 101b: Tapered portion 102: Bearing 103: Coil spring P: Paper

JP 2000-53270 A

Claims (8)

An endless belt,
A plurality of rollers wound around the endless belt so as to be able to travel, the plurality of rollers including at least one end displaceable roller;
A support member for supporting the plurality of rollers;
A shift detection rotating body that is driven to rotate at least one end of the displaceable roller by the endless belt independently of the displaceable roller;
A bearing that supports the shift detection rotating body;
In a belt drive having
The center of the outer shape of the shift detection rotating body supported by the bearing and the axis of the shaft hole supporting the displaceable roller can be shifted, and the displaceable roller can be displaced by the rotation of the shift detection rotating body. A belt driving device having a structure.   A rib for restricting a rotation range of the shift detection rotating body is provided on the shift detection rotating body, and a shape portion that receives the rib is provided on a bearing that supports the shift detection rotating body. The belt drive device according to claim 1.   3. The belt driving device according to claim 1, wherein the shift detection rotating body is provided with a tapered portion that extends from a center side of the displaceable roller toward the bearing side. 4. The shift detection rotating body is provided only on one end side of the displaceable roller,
The displaceable roller is displaced in a state where the endless belt is not in contact with the shift detection rotating body, and the endless belt is biased so as to approach the side where the shift detection rotating body is located. The belt drive device according to any one of claims 1 to 3.   The amount by which the shaft center of the shaft hole supporting the displaceable roller and the center position of the outer shape on which the shift detection rotating body is supported is such that the endless belt is not in contact with the shift detection rotating body. The belt driving device according to claim 4, wherein the belt driving device is set to be not more than twice a displacement amount of the displaceable roller. The offset detection rotating body is provided at both ends of the displaceable roller,
4. The belt driving device according to claim 1, wherein the displaceable roller is not displaced in a state where the endless belt is not in contact with the shift detection rotating body.   A belt transfer device comprising the belt drive device according to claim 1. An image forming apparatus comprising the belt driving device according to claim 1.