JP2021060495A - Belt driving device and image forming apparatus including the same - Google Patents

Abstract

To provide a belt driving device that can prevent clogging, with paper powder, of a gap between a cleaning blade and a belt and maintain cleaning performance and image quality for a long period, and an image forming apparatus including the same.SOLUTION: A belt driving device comprises: an endless belt that is in contact with a sheet on its outer peripheral surface; a plurality of tension rollers that rotatably stretch the belt; and a belt cleaning device. The belt cleaning device has a cleaning blade 32 that is in contact with the outer peripheral surface of the belt, a blade holding member 34 that holds one end of the cleaning blade, and an opposing roller that is opposite to the cleaning blade with the belt therebetween. The cleaning blade has a small flexural rigidity at portions overlapping the edge parts E1, E2 of the sheet compared with that at the other portion.SELECTED DRAWING: Figure 4

Description

The present invention is a belt drive device having a belt cleaning device having a cleaning blade for removing residual toner adhering to an endless belt and an opposing roller arranged to face the cleaning blade, and an image forming device including the cleaning blade. It is about.

Conventionally, an image forming apparatus such as a copier or a printer is provided with a belt cleaning apparatus for removing residual toner adhering to an intermediate transfer belt on which a toner image formed on a photoconductor drum (image carrier) is transferred. It has been known.

The belt cleaning device includes a cleaning blade that removes residual toner adhering to the belt (intermediate transfer belt), an opposing roller that faces the cleaning blade across the belt and is arranged so as to contact the inner peripheral surface of the belt. Has. The belt cleaning device receives the pressure contact force of the cleaning blade by the opposing roller to prevent the belt from escaping (deflecting to the opposite side of the cleaning blade), and removes the residual toner adhering to the belt by the cleaning blade.

In the above belt cleaning device, paper dust is caught in the portion where the pressure of the cleaning blade is concentrated, and the cleaning function of the cleaning blade is impaired. In particular, in the width direction of the belt, paper dust is often generated in the portion where the edge of the paper passes and the portion where the paper feed roller position overlaps, so that the paper dust is generated in the gap between the cleaning blade and the surface of the belt. Is likely to be caught and the residual toner is wiped off.

Conventionally, a method has been adopted in which toner is periodically supplied to the edge portion of the blade to reduce the frictional force at the tip of the blade and allow the tip of the blade to move so that paper dust is not caught. However, there is a problem that the running cost of the apparatus increases because the consumption of toner other than printing increases.

In Patent Document 1, in order to prevent deterioration of image quality due to deformation of the roller that supports and conveys the belt, an elastic body is coated on the outer circumference of the shaft member to form an elastic body layer, and the outer periphery of the elastic body layer of the roller is formed. A belt transfer device including a roller having a diameter formed to be constant along the axial direction and having a diameter at both ends of the outer diameter of the shaft member being smaller than that of the central portion in the axial direction is disclosed.

Patent Document 2 includes an endless belt, a plurality of rollers around which the endless belt is wound, and a cleaning member that comes into contact with the outer peripheral surface of the endless belt to clean the outer peripheral surface of the endless belt. It has a cylindrical central portion and end portions located on both sides of the central portion and decreasing in diameter toward both ends, and the pressure of the cleaning member on the end portion is larger than the pressure of the cleaning member on the central portion. An endless belt drive is disclosed.

Japanese Unexamined Patent Publication No. 6-80268 Japanese Unexamined Patent Publication No. 2015-114357

When the roller described in Patent Document 1 is an opposed roller of the cleaning blade, the pressure of the cleaning blade is uniformly maintained when the roller is stopped. However, when the roller is driven or in a high temperature environment, the elastic layer of the roller thermally expands, the amount of expansion at both ends of the thick roller layer becomes larger than that at the center, and pressure is applied to both ends of the cleaning blade. I will concentrate. Therefore, it is assumed that the gap between the cleaning blade and the belt is clogged with paper dust.

In Patent Document 2, the facing roller has a crown shape in which the diameter is reduced toward both ends, and the distance between the tip of the cleaning blade and the blade holding member is increased with respect to both ends where the pressure between the cleaning blade and the facing roller is reduced. , The rubber thickness of the cleaning blade is increased, and a back support member for supporting the portions corresponding to both ends of the roller of the cleaning blade is added. However, since the pressure of the cleaning blade is not uniform and the pressure of the cleaning blade differs in the longitudinal direction, a large amount of paper dust is clogged at both ends where a particularly high pressure is applied, which stabilizes the cleaning performance and prolongs the service life. Not suitable for.

In view of the above problems, the present invention is a belt drive device capable of preventing paper dust from clogging the gap between the cleaning blade and the belt, and maintaining cleaning performance and image quality for a long period of time, and an image provided with the belt drive device. It is intended to provide a forming apparatus.

In order to achieve the above object, the first configuration of the present invention is a belt driving device including a belt, a plurality of tension rollers, and a belt cleaning device. The belt is endless and the outer peripheral surface contacts the paper. The plurality of tension rollers stretch the belt rotatably. The belt cleaning device includes a cleaning blade, a blade holding member, and an opposing roller. The cleaning blade comes into contact with the outer peripheral surface of the belt and removes foreign matter adhering to the belt. The blade holding member holds one end of the cleaning blade. The opposing rollers are arranged so as to face the cleaning blade with the belt in between and to contact the inner peripheral surface of the belt. The bending rigidity of the portion of the cleaning blade that overlaps the edge portion of the paper is smaller than that of the other portion.

According to the first configuration of the present invention, the cleaning blade is more likely to bend at the portion overlapping the edge portion of the paper to which the paper dust is likely to adhere than the other portions, and the tip portion of the cleaning blade is also easily moved. As a result, it is possible to effectively suppress the pinching of paper dust between the cleaning blade and the belt.

A cross-sectional view schematically showing the structure of an image forming apparatus 100 provided with an intermediate transfer unit 25 according to an embodiment of the present invention. Side sectional view showing the structure around the intermediate transfer unit 25 according to the first embodiment of the present invention. Side sectional view showing the structure around the belt cleaning device 30 constituting the intermediate transfer unit 25 of the first embodiment. Top view showing the structure of the cleaning blade 32 and the blade holding member 34 used in the belt cleaning device 30 constituting the intermediate transfer unit 25 of the first embodiment. Top view showing another configuration of the cleaning blade 32 and the blade holding member 34 used in the belt cleaning device 30 constituting the intermediate transfer unit 25 of the first embodiment. A view of the structure of the cleaning blade 32 and the blade holding member 34 used in the belt cleaning device 30 constituting the intermediate transfer unit 25 according to the second embodiment of the present invention as viewed from the tip end portion 32b side of the cleaning blade 32. A view of another configuration of the cleaning blade 32 and the blade holding member 34 used in the belt cleaning device 30 constituting the intermediate transfer unit 25 of the second embodiment as viewed from the tip portion 32b side of the cleaning blade 32. Cross-sectional view of the opposing roller 40 used in the belt cleaning device 30 constituting the intermediate transfer unit 25 according to the third embodiment of the present invention, cut along the axial direction. Graph showing the relationship between the thickness of EPDM and the coefficient of thermal expansion at 32 ° C.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing an internal structure of an image forming apparatus 100 provided with an intermediate transfer unit 25 according to an embodiment of the present invention. In the main body of the image forming apparatus 100 (here, a color printer), four image forming portions Pa, Pb, Pc and Pd are arranged in order from the upstream side in the transport direction (left side in FIG. 1). These image forming units Pa to Pd are provided corresponding to images of four different colors (cyan, magenta, yellow, and black), and are cyan, magenta, and yellow, respectively, depending on each step of charging, exposure, development, and transfer. And black images are formed sequentially.

Photoreceptor drums (image carriers) 1a, 1b, 1c and 1d that support visible images (toner images) of each color are arranged on these image forming portions Pa to Pd, and further, a belt drive motor ( An intermediate transfer belt 8 that rotates in the counterclockwise direction in FIG. 1 is provided adjacent to each of the image forming portions Pa to Pd (not shown). The toner images formed on the photoconductor drums 1a to 1d are sequentially linearly transferred and superimposed on the intermediate transfer belt 8 that moves while abutting on the photoconductor drums 1a to 1d. After that, the toner image primaryly transferred onto the intermediate transfer belt 8 is secondarily transferred by the secondary transfer roller 9 onto paper P as an example of a recording medium. Further, the paper P on which the toner image is secondarily transferred is discharged from the image forming apparatus 100 main body after the toner image is fixed in the fixing portion 13. The image forming process for each of the photoconductor drums 1a to 1d is executed while rotating the photoconductor drums 1a to 1d in the clockwise direction in FIG.

The paper P on which the toner image is secondarily transferred is housed in a paper cassette 16 arranged in the lower part of the main body of the image forming apparatus 100. The paper P is conveyed to the nip portion between the secondary transfer roller 9 and the drive roller 11 of the intermediate transfer belt 8 via the paper feed roller 12a and the resist roller pair 12b. A sheet made of a dielectric resin is used for the intermediate transfer belt 8, and a seamless (seamless) belt is mainly used. Further, the image forming unit Pd is provided with a belt cleaning device 30 for removing toner and the like remaining on the surface of the intermediate transfer belt 8 on the downstream side of the secondary transfer roller 9.

Next, the image forming units Pa to Pd will be described. Around and below the rotatably arranged photoconductor drums 1a to 1d, charging devices 2a, 2b, 2c and 2d for charging the photoconductor drums 1a to 1d, and image information on the photoconductor drums 1a to 1d. The exposure apparatus 5 for exposing the above, the developing apparatus 3a, 3b, 3c and 3d for forming a toner image on the photoconductor drums 1a to 1d, and the developer (toner) remaining on the photoconductor drums 1a to 1d are removed. Cleaning devices 7a, 7b, 7c and 7d are provided.

When image data is input from a higher-level device such as a personal computer, first, the surfaces of the photoconductor drums 1a to 1d are uniformly charged by the charging devices 2a to 2d. Next, the exposure apparatus 5 irradiates light according to the image data to form an electrostatic latent image corresponding to the image data on the photoconductor drums 1a to 1d. The developing devices 3a to 3d are filled with a predetermined amount of a two-component developer containing toners of cyan, magenta, yellow, and black, respectively. When the ratio of toner in the two-component developer filled in the developing devices 3a to 3d falls below the specified value due to the formation of the toner image described later, the toner containers 4a to 4d to the developing devices 3a to 3d are used. Toner is replenished. The toner in this developer is supplied onto the photoconductor drums 1a to 1d by the developing devices 3a to 3d and electrostatically adheres to the photoconductor drums 1a to 1d. As a result, a toner image corresponding to the electrostatic latent image formed by the exposure from the exposure apparatus 5 is formed.

Then, an electric field is applied between the primary transfer rollers 6a to 6d and the photoconductor drums 1a to 1d at a predetermined transfer voltage by the primary transfer rollers 6a to 6d, and cyan, magenta, yellow, and cyan, magenta, yellow, and cyanide, magenta, and yellow on the photoconductor drums 1a to 1d are applied. The black toner image is primarily transferred onto the intermediate transfer belt 8. These four-color images are formed with a predetermined positional relationship predetermined for forming a predetermined full-color image. After that, in preparation for the subsequent formation of a new electrostatic latent image, the toner and the like remaining on the surfaces of the photoconductor drums 1a to 1d after the primary transfer are removed by the cleaning devices 7a to 7d.

The intermediate transfer belt 8 is hung on the driven roller 10 on the upstream side and the drive roller 11 on the downstream side. When the intermediate transfer belt 8 starts rotating counterclockwise with the rotation of the drive roller 11 by the belt drive motor (not shown), the paper P is adjacent to the drive roller 11 at a predetermined timing from the resist roller pair 12b. It is conveyed to the nip portion (secondary transfer nip portion) with the secondary transfer roller 9 provided in the above. When the paper P passes through the secondary transfer nip portion, the full-color image on the intermediate transfer belt 8 is secondarily transferred onto the paper P. The paper P on which the toner image is secondarily transferred is conveyed to the fixing portion 13.

The paper P conveyed to the fixing portion 13 is heated and pressurized by the fixing roller pair 13a to fix the toner image on the surface of the paper P, and a predetermined full-color image is formed. The paper P on which the full-color image is formed is distributed in the transport direction by the branch member 21 arranged at the branch portion of the paper transport path 18 via the transport roller pair 15, and is fed as it is (or sent to the double-sided transport path 22 on both sides). After printing), it is ejected to the eject tray 20 by the eject roller pair 19.

Next, the structure of the intermediate transfer unit 25 and its surroundings will be described. FIG. 2 is a side sectional view showing the structure of the intermediate transfer unit 25 according to the first embodiment of the present invention. FIG. 3 is a side sectional view showing the structure around the belt cleaning device 30 constituting the intermediate transfer unit 25 of the first embodiment.

As shown in FIG. 2, the intermediate transfer unit 25 includes primary transfer rollers 6a to 6d, an intermediate transfer belt 8, a driven roller 10, a drive roller 11, and a belt cleaning device 30. The intermediate transfer belt 8 is rotatably stretched on a plurality of tension rollers. The tension rollers are arranged at one end (right end) of the photoconductor drums 1a to 1d in the arrangement direction (left-right direction in FIG. 2), and the drive roller 11 for rotationally driving the intermediate transfer belt 8 and the other end (the other end in the arrangement direction). The driven roller 10 arranged at the left end) and the primary transfer rollers 6a to 6d are included.

The belt cleaning device 30 is arranged on the downstream side in the rotation direction of the intermediate transfer belt 8 from the drive roller 11 and on the upstream side in the rotation direction of the intermediate transfer belt 8 from the driven roller 10. As shown in FIG. 3, the belt cleaning device 30 includes a housing 31, a cleaning blade 32, a recovery screw 33, a blade holding member 34, a sealing member 35, and an opposing roller 40.

The housing 31 has an opening 31a facing the intermediate transfer belt 8 and a waste toner accommodating portion 31b for accommodating the waste toner scraped from the surface of the intermediate transfer belt 8.

The cleaning blade 32 comes into contact with the outer peripheral surface of the intermediate transfer belt 8 and removes residual toner adhering to the intermediate transfer belt 8. As the cleaning blade 32, for example, a blade made of polyurethane rubber is used. The blade holding member 34 is made of metal and is attached to the opening 31a of the housing 31 on the downstream side (left side in FIG. 3) of the intermediate transfer belt 8 in the moving direction (arrow A direction).

The base end portion 32a side of the cleaning blade 32 is fixed to the blade holding member 34, and the tip end portion 32b is attached at a predetermined angle toward the upstream side in the moving direction of the intermediate transfer belt 8 (counter direction). The material and hardness of the cleaning blade 32, the dimensions, the amount of biting into the intermediate transfer belt 8, the pressure contact force, the mounting angle, and the like are appropriately set according to the specifications of the intermediate transfer belt 8.

Opposing rollers 40 that receive the pressure contact force of the cleaning blade 32 are arranged at positions facing the cleaning blade 32 with the intermediate transfer belt 8 interposed therebetween. The opposing roller 40 is composed of a core metal 40a and an elastic layer 40b loaded on the outer peripheral surface of the core metal 40a. As the elastic layer 40b, for example, EPDM (ethylene propylene diene rubber) or the like is used. The opposing roller 40 is rotated in the counterclockwise direction of FIG. 3 at the same linear speed as the intermediate transfer belt 8 by a driving force from the same drive source (belt drive motor) as the drive roller 11. The apex (top) of the opposing roller 40 is arranged slightly above the apex of the driving roller 11 and the apex of the driven roller 10.

The residual toner removed from the surface of the intermediate transfer belt 8 by the cleaning blade 32 is discharged to the outside of the belt cleaning device 30 as the recovery screw 33 rotates, and is conveyed to and stored in a toner recovery container (not shown). Toner.

The seal member 35 is a sheet-like member attached to the upstream side (right side in FIG. 3) of the intermediate transfer belt 8 in the opening 31a of the housing 31 in the rotational direction. One end (right end in FIG. 3) of the seal member 35 is adhesively fixed to the housing 31, and the other end (left end in FIG. 3) forms a free end. The free end of the seal member 35 is in contact with the outer peripheral surface of the intermediate transfer belt 8 toward the downstream side in the rotational direction of the intermediate transfer belt 8. The sealing member 35 suppresses the leakage of waste toner in the housing 31 from the gap between the housing 31 and the intermediate transfer belt 8. As the sealing member 35, for example, a urethane sheet having a thickness of 100 μm is used, but a thin plate-shaped sheet other than the urethane sheet may be used.

As described above, the cleaning blade 32 is arranged in the counter direction with respect to the moving direction of the intermediate transfer belt 8. Therefore, a strong contact pressure is applied between the cleaning blade 32 and the intermediate transfer belt 8 (hereinafter, referred to as the blade-belt). If the contact pressure between the blade and the belt is too strong, the tip portion 32a of the cleaning blade 32 will not move, and the paper dust sandwiched between the blade and the belt will not easily come off. As a result, the cleaning function of the cleaning blade 32 is impaired. In addition, the surface of the intermediate transfer belt 8 may be scratched.

Therefore, in the present invention, the bending rigidity of the cleaning blade 32 is reduced in the portion of the intermediate transfer belt 8 where paper dust easily adheres so that the movement of the tip portion 32b is not hindered. It suppresses the sandwiching of powder.

FIG. 4 is a plan view showing the configurations of the cleaning blade 32 and the blade holding member 34 used in the belt cleaning device 30 constituting the intermediate transfer unit 25 of the first embodiment. As shown in FIG. 4, the upstream end portion (upper end portion in FIG. 4) of the blade holding member 34 with respect to the moving direction of the intermediate transfer belt 8 (direction of arrow A) is orthogonal to the moving direction of the intermediate transfer belt 8. Concavities and convexities are formed at predetermined intervals in the width direction (horizontal direction in FIG. 4). Therefore, the length (free length) from the tip end portion 32b of the cleaning blade 32 to the edge of the blade holding member 34 is different in the width direction.

Specifically, the free length d1 of the portion overlapping the edge portions E1 and E2 of the paper P of a plurality of types (here, A4 size and A4R size) conveyed by the image forming apparatus 100 becomes the free length d2 of the other portion. It is composed longer than that.

According to the configuration of FIG. 4, the bending rigidity of the cleaning blade 32 is small (easily bent) at the portion of the paper P where the paper dust easily adheres and overlaps with the edges E1 and E2, and the tip portion 32b of the cleaning blade 32 is also easy to move. Become. As a result, it is possible to effectively suppress the pinching of paper dust between the blade and the belt.

In the configuration of FIG. 4, the free length d1 of the portion overlapping the edge portions E1 and E2 of the two types of paper P of A4 size and A4R size is made longer than the free length d2 of the other portion. When the 100 can convey three or more sizes of paper P, the free length of the portion overlapping the edge portion of the paper P of each size may be longer than that of the other portions.

FIG. 5 is a plan view showing another configuration of the cleaning blade 32 and the blade holding member 34 used in the belt cleaning device 30. In the configuration example shown in FIG. 5, the free length of the portion overlapping the edge portion E1 of the A4 size (large size) paper P and the portion overlapping the entire paper width including the edge portion E2 of the A4R size (small size) paper P. d1 is configured to be longer than the free length d2 of other parts.

According to the configuration of FIG. 5, the free length of the cleaning blade 32b becomes longer at the portion overlapping the roller width Rw of the paper feed roller 12a (see FIG. 1) in addition to the portion overlapping the edge portions E1 and E2 of the paper P. As a result, the bending rigidity of the cleaning blade 32 becomes small (easily flexed) at the portion overlapping the edges E1 and E2 of the paper P to which the paper dust easily adheres and the portion overlapping the paper feed roller 12a, and the tip portion of the cleaning blade 32 Since 32b also becomes easy to move, it is possible to more effectively suppress the pinching of paper dust between the blade and the belt.

In the configuration of FIG. 5, the free length d1 of the portion overlapping the entire width of the A4R size paper P including the edge portion E2 is longer than the free length d2 of the other portion, but the size is smaller than the A4R size. When paper P of (for example, A5R size) can be passed through, the free length d1 of the portion overlapping the entire width of the paper including the edge portion E2 of the minimum size (A5R size) paper P that can be passed through is set to another portion. It may be longer than the free length d2 of.

FIG. 6 is a view of the configuration of the cleaning blade 32 and the blade holding member 34 used in the belt cleaning device 30 constituting the intermediate transfer unit 25 according to the second embodiment of the present invention as viewed from the tip end portion 32b side of the cleaning blade. is there. As shown in FIG. 6, the cleaning blade 32 is formed with irregularities at predetermined intervals in the width direction (horizontal direction in FIG. 6) orthogonal to the moving direction of the intermediate transfer belt 8, and the thickness of the cleaning blade 32 is wide. Different in direction. Specifically, the thickness t1 of the portion overlapping the edge portions E1 and E2 of the A4 size and A4R size paper P is configured to be thinner than the thickness t2 of the other portion.

According to the configuration of FIG. 6, the bending rigidity of the cleaning blade 32 becomes small (easily flexed) at the portion of the paper P where the paper dust easily adheres and overlaps with the edge portions E1 and E2, and the tip portion 32b of the cleaning blade 32 also easily moves. Become. As a result, it is possible to effectively suppress the pinching of paper dust between the blade and the belt.

In FIG. 6, only the portion of the paper P overlapping the edge portions E1 and E2 is made thinner than the other portions, but as shown in FIG. 7, the portion overlapping the edge portion E1 and the minimum size (A4R size) ), The thickness t1 of the portion overlapping the entire width of the paper including the edge portion E2 of the paper P may be made thinner than the thickness t2 of the other portion. According to this configuration, it is effective to sandwich the paper dust between the blade and the belt in the portion of the paper P on which the paper dust easily adheres, which overlaps with the edges E1 and E2, and the portion of the paper feed roller 12a which overlaps with the roller width Rw. Can be suppressed.

FIG. 8 is a cross-sectional view of the opposing roller 40 used in the belt cleaning device 30 constituting the intermediate transfer unit 25 according to the third embodiment of the present invention, cut along the axial direction. In the third embodiment, the flexibility of the tip portion 32b of the cleaning blade 32 is adjusted by changing the thickness of the elastic layer 40b of the opposing roller 40 in the axial direction. The configuration of the cleaning blade 32 that is pressed against the opposing roller 40 with the intermediate transfer belt 8 interposed therebetween is the same as that of the first embodiment.

As shown in FIG. 8, the thickness t3 of the elastic layer 40b of the portion overlapping the edges E1 and E2 of the A4 size and A4R size paper P and the portion overlapping the roller width Rw of the paper feed roller 12a is the other portion. It is configured to be thinner than the thickness t4.

According to the configuration of FIG. 8, the thickness of the elastic layer 40b is reduced at the portion of the paper P on which the paper dust easily adheres, which overlaps with the edges E1 and E2, and the portion of the paper P which overlaps with the paper feed roller 12a. Therefore, the coefficient of thermal expansion of the opposing roller 40 (elastic layer 40b) in the portion where paper dust easily adheres is smaller than that in the other portion.

As a result, when the opposing roller 40 is thermally expanded by the heat generated by driving the intermediate transfer belt 8 or the heat generated from the fixing portion 13 or the like in the image forming apparatus 100, the cleaning blade in the portion where paper dust easily adheres. The increase in pressure of 32 can be suppressed. Therefore, since the flexural rigidity (easiness of bending) of the cleaning blade 32 and the ease of movement of the tip portion 32b can be maintained, it is possible to effectively suppress the pinching of paper dust between the blade and the belt regardless of changes in environmental conditions. Can be done.

Others The present invention is not limited to each of the above embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, the cleaning blade 32 and the blade holding member 34 used in the first and second embodiments may be combined. Alternatively, the cleaning blade 32 and the blade holding member 34 used in the second embodiment may be combined with the opposing roller 40 used in the third embodiment.

Further, in each of the above embodiments, the belt cleaning device 30 for cleaning the intermediate transfer belt 8 used in the intermediate transfer type image forming apparatus 100 has been described, but instead of the intermediate transfer belt 8, the paper P is used for each image forming unit Pa. It can also be used as a belt cleaning device for cleaning a transfer transfer belt in a direct transfer type image forming apparatus provided with a transfer transfer belt that sequentially conveys to Pb.

Further, the present invention is not limited to the color printer as shown in FIG. 1, and can be applied to various image forming devices including a belt cleaning device such as a digital multifunction device, a color copier, and a facsimile. Hereinafter, the effects of the present invention will be described in more detail with reference to Examples.

The relationship between the free length and thickness of the cleaning blade 32 and the blade linear pressure (contact pressure), and the relationship between the thickness of the elastic layer 40b of the opposing roller 40 and the coefficient of thermal expansion were investigated. The cleaning blade 32 is a flat plate made of polyurethane rubber having a width direction length of 217 mm, a thickness of 1.6 mm, a thickness of 1.8 mm, a 2.0 mm, a 2.2 mm, and a free length of 8 mm from the counter direction with respect to the intermediate transfer belt 8. It was fixed so as to be 10 mm, 12 mm, and 14 mm. Then, the blade linear pressure when the intermediate transfer belt 8 was driven was measured. The results are shown in Table 1.

As the opposing roller 40, the elastic layer 40b made of EPDM having thicknesses of 0.3 mm, 0.5 mm, and 1.2 mm was used. Then, the coefficient of thermal expansion when the temperature was changed to 2 ° C., 12 ° C., 22 ° C., 32 ° C., and 42 ° C. with reference to 22 ° C. was measured. The results are shown in Table 2. Further, FIG. 9 shows the relationship between the thickness of EPDM and the coefficient of thermal expansion at 32 ° C.

The blade linear pressure at which the residual toner can be cleaned by the cleaning blade 32 is 0.7 gf / mm or more. Further, when the blade linear pressure becomes 2.2 gf / mm or more, the cleaning blade 32 is rolled up. Therefore, it is desirable that the blade linear pressure is 0.7 gf / mm or more and less than 2.2 gf / mm.

From Table 1, for example, the thickness t1 of the cleaning blade 32 and the free length d1 of the portion having a large amount of paper dust (the portion overlapping the edge portions E1 and E2 and the portion overlapping the paper feed roller 12a) are set to 1.8 mm and the free length d1 is set to 12 mm. It can be seen that it is effective to set the thickness t2 of the cleaning blade 32 of the other portion to 2.0 mm and the free length d2 to 10 mm.

From Table 2, for example, the thickness t3 of the elastic layer 40b of the portion having a large amount of paper dust (the portion overlapping the edge portions E1 and E2 and the portion overlapping the paper feed roller 12a) is 0.3 mm, and the thickness of the elastic layer 40b of the other portion. It can be seen that it is effective to set t4 to 0.5 mm.

The present invention can be used in a belt drive device including a belt cleaning device having a cleaning blade for removing residual toner adhering to an endless belt and an opposing roller arranged to face the cleaning blade. By utilizing the present invention, a belt drive device capable of preventing paper dust from clogging in the gap between the cleaning blade and the belt and maintaining cleaning performance and image quality for a long period of time and an image forming device provided with the belt drive device can be provided. Can be provided.

1a-1d Photoreceptor drum (image carrier)
6a-6d Primary transfer roller (tension roller)
8 Intermediate transfer belt 10 Driven roller (tension roller)
11 Drive roller (tension roller)
25 Intermediate transfer unit (belt drive device)
30 Belt cleaning device 32 Cleaning blade 34 Blade holding member 40 Opposing roller 40a Core metal 40b Elastic layer 100 Image forming device P paper

Claims (8)

An endless belt whose outer peripheral surface contacts the paper,
A plurality of tension rollers for rotatably tensioning the belt, and
A cleaning blade that comes into contact with the outer peripheral surface of the belt to remove foreign matter adhering to the belt, a blade holding member that holds one end of the cleaning blade, and a belt that faces the cleaning blade with the belt sandwiched between them. A belt cleaning device having an opposed roller arranged so as to be in contact with the inner peripheral surface of the belt.
In the belt drive device equipped with
The cleaning blade is a belt driving device characterized in that the bending rigidity of a portion overlapping the edge portion of the paper is smaller than that of other portions. The belt driving device according to claim 1, wherein the cleaning blade has a flexural rigidity of a portion overlapping a position in the width direction of a paper feed roller that supplies the paper to the belt, as compared with other portions. The cleaning blade according to claim 2, wherein the flexural rigidity of a portion of the cleaning blade that overlaps the entire width direction including the edge portion of the paper having the smallest size in contact with the outer peripheral surface of the belt is smaller than that of the other portions. Belt drive. The free length from the tip end portion in contact with the outer peripheral surface of the belt to the edge of the blade holding member in the portion where the bending rigidity of the cleaning blade is small is longer than the free length of the other portion. The belt driving device according to any one of claims 1 to 3. The belt driving device according to any one of claims 1 to 4, wherein the thickness of the portion of the cleaning blade having a small flexural rigidity is smaller than the thickness of the other portion. The opposing roller has a core metal and an elastic layer laminated on the outer peripheral surface of the core metal, the outer diameter of the opposing roller is uniform in the axial direction, and the flexural rigidity of the cleaning blade in the axial direction. The belt driving device according to any one of claims 1 to 5, wherein the thickness of the elastic layer of the portion facing the small portion is thinner than the thickness of the other portion. An image forming apparatus including the belt driving device according to any one of claims 1 to 6. Image carrier and
A developing device that develops an electrostatic latent image formed on the surface of the image carrier into a toner image, and
With
The image forming apparatus according to claim 7, wherein the belt is an intermediate transfer belt on which the toner image formed on the image carrier is primarily transferred.

Images