JP2009186600A - Cleaning device, intermediate transfer unit, transfer conveyance unit, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure belt replaceability and a winding angle with respect to a driving roller, while achieving positional accuracy with respect to the belt of a cleaning member in a cleaning unit and space saving. <P>SOLUTION: An opposing roller 50 is provided on the belt inner circumferential side of a belt unit, the cleaning unit having a supporting shaft fitted to a shaft core of the opposing roller 50 is attached to the belt unit and the cleaning member 61 of the cleaning unit comes into press-contact with the opposing roller 50 through the belt 10. At the same time, it is configured such that: a pressing member is pressed from a belt surface side to apply some tension to the belt 10; and the belt 10 is wound on the opposing roller 50 by a predetermined amount. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus. Specifically, the present invention relates to an intermediate transfer unit, a transfer conveyance unit used therefor, and a cleaning device used therefor.

  2. Description of the Related Art Conventionally, there have been inventions in which a roller or the like is pressed from the belt surface to improve the degree of freedom of scooping the belt unit (transfer belt unit) or to save space. By pressing the roller from the belt surface to save space, the unit is made thinner, and at the same time, the belt wrap angle around the drive roller is increased to prevent belt slip and stabilize belt running. (For example, refer to Patent Document 1). However, these inventions merely dispose the roller in the belt unit, and do not particularly mention the relationship with the cleaning device.

The life on the belt unit side and the life on the cleaning unit side are often different. For example, there is a case where only the belt is desired to be replaced. Since the cleaning unit has a portion in contact with the belt and contact pressure is also applied, the pressure of the cleaning unit must be released when the belt is replaced. Generally, the cleaning unit is configured to be detachable from the belt unit, and the belt unit is attached to the image forming apparatus main body with the cleaning unit assembled. Therefore, in the case of belt replacement, the belt unit is taken out from the apparatus main body together with the cleaning unit, and then the cleaning unit is removed from the belt unit, and then the belt is removed from the belt unit. Since the belt unit hangs an endless belt on a plurality of rollers and applies a predetermined tension to the belt, the tension must be released to remove the belt.
A configuration of a belt unit and a cleaning unit that eliminates the complexity of the belt replacement procedure is desired.

JP 2004-198680 A

Conventionally, a belt unit is configured by winding a belt around a driving roller and a driven roller. However, in such a configuration, there is a limit to downsizing the belt unit. This is because the driving roller and the driven roller need to apply a force of a certain level or more to the belt, and if the size is reduced, the belt is bent and wrinkled.
As the above countermeasure, a configuration has been proposed in which a roller is pressed from the outside of the belt to bend the belt traveling path as in Patent Document 1. However, in such a case, it is necessary to remove a roller for bending the belt (hereinafter referred to as a bending roller) when replacing the belt. In other words, service work procedures have increased.
On the other hand, it has been necessary to remove the belt cleaning device from the belt unit when replacing the belt. Therefore, Patent Document 1 proposes to use a curved roller also as a cleaning roller. However, with such a configuration, the positional relationship between the cleaning roller and the belt cannot be ensured with high accuracy. This is because, as described above, the bending roller needs to be configured to be removable and cannot be fixed. Wear of the attachment portion due to removal work or the like also hinders position accuracy. In recent years, in order to improve the image quality, the toner has been reduced in diameter and sphere, but this type of toner is very difficult to clean. Ensuring the positional accuracy of the cleaning member and the belt has become extremely important.
An object of the present invention is to simultaneously achieve improvement of belt exchangeability and securing of positional accuracy of cleaning conditions, which have been difficult to achieve, without sacrificing conventional performance requirements such as space saving.

According to the first aspect of the present invention, in the cleaning device for removing the residual toner on the belt surface of the endless belt unit for the image carrier suspended from a plurality of support rollers, the cleaning device includes at least one pressing member and A cleaning unit integrally having a single cleaning member and configured to be attachable to the endless belt unit, and a fixed position opposite the inner periphery of the endless belt at a position facing the cleaning member A roller, and when the cleaning unit is mounted, the pressing member and the cleaning member are in contact with the endless belt, and the back surface of the endless belt is in contact with the opposing roller at a predetermined winding angle. To do.
According to a second aspect of the present invention, in the cleaning device according to the first aspect, the pressing member is a roller.

According to a third aspect of the present invention, in the cleaning device according to the second aspect, the pressing member has a surface roughness Rmax of 30 μm or less.
According to a fourth aspect of the present invention, in the cleaning device according to any one of the first to third aspects, the pressing member is in the unit and is downstream of the cleaning member in the endless belt moving direction. It is provided.

According to a fifth aspect of the present invention, in the cleaning device according to any one of the first to fourth aspects, the length of the pressing member in the belt width direction is equal to or greater than the width of the endless belt. To do.
According to a sixth aspect of the present invention, in the cleaning device according to any one of the first to fifth aspects, the cleaning unit positions the opposed roller and then positions the pressing member relative to the endless belt. It is characterized by performing.

According to a seventh aspect of the present invention, in the intermediate transfer unit comprising a plurality of transfer means and a cleaning device, the cleaning device is the cleaning device according to any one of the first to sixth aspects, and the cleaning device The apparatus is characterized in that, among the plurality of transfer means, the apparatus is disposed immediately before the transfer means positioned at the most upstream position in the belt running direction.
According to an eighth aspect of the present invention, in the transfer conveyance unit comprising a plurality of transfer means and a cleaning device, the cleaning device is the cleaning device according to any one of the first to sixth aspects, and the cleaning device The apparatus is characterized in that, among the plurality of transfer means, the apparatus is disposed immediately before the transfer means positioned at the most upstream position in the belt running direction.

According to a ninth aspect of the invention, there is provided an image forming apparatus using the intermediate transfer unit according to the seventh aspect.
According to a tenth aspect of the present invention, an image forming apparatus using the transfer conveyance unit according to the eighth aspect is characterized.
According to an eleventh aspect of the present invention, in the image forming apparatus according to the ninth or tenth aspect, the plurality of transfer nips formed by the plurality of transfer units and the belt contact portion of the pressing member are substantially in a straight line. The belt running direction between the pressing member and the nearest transfer means is substantially parallel to the belt running direction between the transfer means.

  According to the present invention, a member that presses against the belt surface is provided on the side of the cleaning unit that is disposed with respect to the cleaning-opposing roller disposed inside the belt unit, so that the cleaning member in the cleaning unit against the belt is provided. While achieving positional accuracy and space saving, it is possible to achieve belt interchangeability and secure the winding angle with the drive roller.

FIG. 1 is a diagram showing an embodiment of the present invention.
In the figure, reference numeral 1 is a photosensitive member, 2 is a photosensitive member cleaning device, 3 is a cleaning blade, 4 is a charging device, 6, 7, 8, and 9 are developing devices, 10 is an intermediate transfer member (belt), and 11 is a primary. 12, 13 and 14 are support rollers, 19 is a belt cleaning unit, 21 is a secondary transfer roller, 25 is a paper feed cassette, 26 is a paper feed roller, 27 is a transport roller, 28 is a registration roller, and 30 is fixing. The apparatus includes a discharge roller, a toner collection bottle 40, an exposure apparatus 41, a counter roller 50, a primary transfer bias control unit 101, and a secondary transfer bias control unit 102.
The figure shows a tandem indirect (intermediate) transfer type electrophotographic apparatus.
The copying machine main body is provided with an endless belt 10 used as an intermediate transfer member at the center. The belt 10 may have a multilayer structure or a single layer structure. In the case of a multi-layer structure, the base layer is made of, for example, a fluororesin or PVDF sheet with little elongation and a polyimide resin, and the surface is covered with a smooth coat layer such as a fluororesin. Some use materials such as PC and polyimide. In the present invention, it is not particularly necessary to specify the material of the belt.
Then, as shown in FIG. 1, in the illustrated example, it is wound around the support rollers 12, 13, and 14 so as to be able to rotate and convey counterclockwise in the figure. These support roller, transfer device, and belt 10 are integrated to form an intermediate transfer unit.

  In this illustrated example, a belt cleaning unit 19 for removing residual toner remaining on the belt 10 after image transfer is provided on the left of the support roller 12. The cleaning unit 19 is incorporated in the apparatus after being integrated with the intermediate transfer body unit in advance outside the apparatus. Further, a blade-like member such as urethane is used as the cleaning member and is in contact with the belt in the counter direction with respect to the belt rotation direction. Although not shown, the cleaning member may be configured to be electrostatically recovered using a conductive brush or roller in addition to the urethane blade. Further, the toner collected by the blade is conveyed to the back side of the apparatus by a conveying member in the cleaning apparatus, and is stored in the toner collection bottle 40 by being dropped downward by gravity or the like. Although not shown, the toner collection bottle is provided with means for detecting the amount of collected toner, and the toner is prevented from overflowing by stopping the machine when the bottle is full.

Four image forming units of black, magenta, cyan, and yellow are arranged side by side on the belt 10 substantially in parallel with the traveling direction of the belt 10 that travels through the cleaning device unit, and arranged in tandem. An image forming apparatus is configured.
An exposure device 41 is provided on the tandem image forming apparatus.
On the other hand, a secondary transfer roller 21 is provided on the opposite side of the belt 10 to the support roller 12.
A fixing device 30 for fixing the transferred image on the sheet is provided on the secondary transfer roller. The fixing device 30 is configured by pressing a pressure roller against a fixing roller.

  When a start switch (not shown) is pressed, one of the support rollers 12, 13, and 14 is rotationally driven by a drive motor (not shown), the other support rollers are driven to rotate, and the belt 10 is rotated and conveyed. At the same time, the photosensitive member 1 is rotated by individual image forming means to form black, magenta, cyan, and yellow single-color images on each photosensitive member 1, respectively. Then, along with the conveyance of the belt 10, the monochrome images are sequentially transferred to form a composite color image on the belt 10.

On the other hand, when the start switch is pressed, one of the paper feed rollers 26 of the paper feed table is selectively rotated, the sheet is fed out from one of the paper feed cassettes 25 provided in multiple stages in the paper bank, and one sheet is fed by the separation roller. The paper is separated and put into the paper feed path, transported by the transport roller 27, guided to the paper feed path in the copying machine main body, and abutted against the registration roller 28 and stopped.
Then, the registration roller 28 is rotated in synchronization with the synthesized color image on the belt 10, the sheet is fed between the belt 10 and the secondary transfer roller, and is transferred by the secondary transfer roller 21 to be transferred onto the sheet. Record.
The image-transferred sheet is conveyed by the secondary transfer roller 21 and sent to the fixing device 30. The fixing device 30 applies heat and pressure to fix the transferred image, and is then discharged by the discharge roller 32 and discharged. Stack on paper tray.
The belt 10 after the image transfer is removed by the belt cleaning unit 19 to remove residual toner remaining on the belt 10 after the image transfer, and is ready for re-image formation by the tandem image forming apparatus.

FIG. 2 is a diagram for explaining the configuration of the cleaning device.
In the figure, reference numeral 60 denotes a residual toner conveying screw, 61 denotes a cleaning member, 62 denotes a lubricant application roller, and 63 denotes a lubricant.
As described above, the cleaning unit 19 for removing the residual toner on the belt after the paper transfer by the secondary transfer roller 21 is configured to face the cleaning counter roller 50 in the belt. . Since the opposing roller 50 is fixed in position and performs a cleaning function in cooperation with the cleaning unit 19, the cleaning unit 19 and the opposing roller 50 together constitute a cleaning means (hereinafter referred to as a cleaning device). In the cleaning unit 19, as shown in the figure, a cleaning blade 61 as a cleaning member is positioned with respect to the opposing roller 50 via the belt 10, and the opposing roller 50 receives the contact pressure of the cleaning blade 61 with respect to the belt 10. The mutual positional relationship is determined. However, if the belt 10 and the opposing roller 50 are in point contact in the cross-sectional view, the contact position of the cleaning blade 61 is required to have extremely high accuracy. Therefore, as will be described later, the belt 10 is slightly wound around the opposing roller 50 so as to widen the contact range between them.
Lubricant application made with a brush (rubber, sponge, metal, etc.) to eliminate uneven application of lubricant 63 with zinc stearate to ensure transferability and belt cleaning A configuration may be adopted in which the belt 10 is applied via the roller 62.

In the present invention, a pressing roller 19a is provided on the cleaning unit 19 side as a pressing member for winding the belt 10 around the opposing roller 50 (expanding the contact range). The pressing roller 19a is fixed on the cleaning unit side, and is configured integrally with a cleaning member in the cleaning unit in a state set on the unit side. In a state before the cleaning unit is mounted, the facing roller 50 is in a position close to the belt 10 but is not particularly guaranteed to contact.
By attaching the cleaning unit, the pressing roller 19a and the cleaning blade 61 come into contact with the belt. The amount by which the pressing roller 19a pushes the belt 10 is predetermined, and is regulated by a stopper means (not shown) provided between the cleaning unit and the intermediate transfer body unit.

As a specific example, a support shaft (not shown) of the cleaning unit 19 is rotatably attached to the rotation center of the opposing roller 50, and the position of the cleaning blade 61 (from the axis of the opposing roller 50) Distance) is defined. Next, by rotating the cleaning unit 19 counterclockwise, a pressing amount of the pressing roller 19a with respect to the belt 10 is defined by a stopper means (not shown) provided between the intermediate transfer body unit and the cleaning unit. Usually, when the above position is determined, the cleaning unit is fixed to the intermediate transfer body unit by screws or the like.
With this configuration, when the pressing roller 19a is positioned, the distance of the cleaning blade 61 positioned before the pressing roller 19a from the axis of the opposing roller 50 does not change.

When the pressing amount of the pressing roller 19a with respect to the belt 10 is determined, the belt 10 is configured to be wound around the opposing roller 50 by a predetermined angle. Since the cleaning blade 61 can perform a desired cleaning function within this range, the required accuracy of the contact position of the cleaning blade 61 is moderated, and it is easy to configure, leading to a reduction in manufacturing cost.
When the pressure roller 19 comes into contact and reaches a predetermined position, tension is generated in the belt 10, so that the pressure roller 19 can have a role of a so-called tension roller without providing the stopper means. .
Since the pressing roller 19a is a rotating body, the frictional force (load resistance) with the belt 10 is reduced, so that an increase in load on the belt driving torque can be prevented, and damage to the surface of the belt 10 is also prevented. be able to.
By disposing the pressure roller 19a on the downstream side of the cleaning blade 61, the pressure roller 19a contacts the belt 10 after the residual toner is removed, so that contamination by toner can be prevented.

By providing the pressing roller 19a on the side of the cleaning unit as in the present invention, when the cleaning unit is removed, the pressure on the belt 10 is released, so that the exchangeability of the belt 10 is facilitated and the inside of the cleaning device is The positional accuracy between each component and the intermediate transfer unit is also improved. The reason is that if the cleaning device is positioned directly on the opposite roller on the belt 10 side, the absolute position of the components in the unit integrally provided in the case of the cleaning unit changes simultaneously with the pressing roller 19a. By using the stopper, the relative position with respect to the belt surface determined by the pressing roller 19a can be arranged without any deviation.
When the pressing roller 19a has a role of a tension roller for the belt 10, the cleaning unit 19 can be rotated around the rotation point P, for example, at the upper right corner in FIG. Also good. In the case of the rotation method, a constant tension can be applied to the belt 10 by applying the rotational force with a constant spring force.

  The life of the belt 10 cleaning device is often different from the life on the belt 10 side. As a maintenance mode, the intermediate transfer belt unit and the belt 10 cleaning device can be easily attached and detached. Conventionally, a method for enabling the exchange of the above is often used. Therefore, if the pressing roller 19a is provided on the cleaning device side of the belt 10 that is easy to attach and detach, the belt 10 may be replaced due to some trouble by removing the cleaning unit that can be easily removed. However, since the pressure can be easily released, it can be easily replaced. Further, since the pressing roller is pressed from the surface side of the belt 10, if the configuration as in this embodiment is taken, the winding angle to the driving roller 12 is increased in a small space, and the belt 10 is driven. The margin for slip increases.

If the position of the stopper is arranged so that the position of the pressing roller 19a (direction perpendicular to the belt surface: Y direction in the figure) is substantially the same horizontal height position as the primary transfer nip position with the photosensitive member, the apparatus main body Further, when the intermediate transfer unit is attached or detached, it can be performed in as little space as possible. The belt surface is kept substantially the same with respect to the primary transfer nip position and the Y direction by the pressure roller 19a, and the belt 10 passing through the four transfer units 11a to 11d and the pressure roller 19a appears to be in a straight line. Actually, the belt 10 is slightly bent at the transfer nip and is not a strict straight line. However, the belt running directions between the transfer means are parallel to each other, and similarly, the transfer means (the same transfer means) as that of the pressing roller 19a. In the case of the figure, the belt running direction between 11a) is also parallel to them. By doing so, there is an effect that the wrapping angle of the belt 10 with respect to the photosensitive member in each transfer nip is made equal, and the transfer efficiency is made constant.
In addition, with this configuration, when the intermediate transfer unit is pulled out from the main body, the belt surface and the photosensitive member surface can be pulled out without rubbing only by slightly reducing the unit, and scratches due to rubbing can be easily prevented. Also, by positioning the pressing roller 19a in the belt contact state on a substantially straight line connecting the transfer nip position with each photoconductor, it becomes easy to manage the transfer nip shape (width and winding position), and the distance between each color nip is the same. This is also desirable from the viewpoint of alignment.

  The axial length of the pressing roller 19a is preferably set longer than the belt width. The reason is that when the tension applied to the belt 10 is taken into consideration, the tension applied to the belt in the belt axial direction is naturally stabilized when the pressing member is in contact with the entire belt width direction. Accordingly, since there is no bias in the left and right belt tensions in the axial direction, it is possible to prevent a problem that the belt is caused by either the axial direction.

  Further, since the pressing roller 19a is pressed against the belt surface, the belt is scratched, which causes damage to the belt cleaning member, resulting in insufficient cleaning on the belt and abnormal image (belt Cleaning failure). Therefore, the surface of the pressing roller 19a is selected from a material that is sufficiently soft with respect to the belt, or even when a hard roller such as a metal is selected, the surface roughness can be reduced to 30 μm or less by Rmax. It is possible to prevent scratches. This is because when the surface roughness of the pressure roller 19a is changed within a certain range and the endurance test of the intermediate transfer belt is performed, if the surface roughness of the pressure roller 19a is Rmax of 30 μm or less, several types (PI, PAI, PVDF, PC) It was judged from the fact that there was no problem in the belt material.

  As described above, the cleaning device of the present invention is superior to the conventional invention. If the device is used as a direct transfer type transfer conveyance unit or an indirect transfer type intermediate transfer unit and mounted on an image forming apparatus or the like, the cleaning performance is improved. It is also possible to provide a space-saving and highly reliable device.

It is a figure which shows one embodiment of this invention. It is a figure for demonstrating the structure of a cleaning apparatus.

Explanation of symbols

1 Photosensitive member 10 Intermediate transfer member (belt)
11 Primary transfer device 12, 13, 14 Support roller 19 Belt cleaning unit 19a Press member 50 Opposing roller 61 Cleaning member

Claims (11)

  In a cleaning device that removes residual toner on a belt surface of an endless belt unit for an image carrier suspended by a plurality of support rollers, the cleaning device integrally includes at least one pressing member and one cleaning member. A cleaning unit configured to be attachable to the endless belt unit, and a counter roller fixed to a position close to the inner periphery of the endless belt at a position facing the cleaning member. The cleaning device, wherein when the unit is mounted, the pressing member and the cleaning member are in contact with the endless belt, and the back surface of the endless belt is in contact with the counter roller at a predetermined winding angle.   The cleaning device according to claim 1, wherein the pressing member is a roller.   The cleaning device according to claim 2, wherein the pressing member has a surface roughness Rmax of 30 μm or less.   The cleaning apparatus according to claim 1, wherein the pressing member is provided in the unit and downstream of the cleaning member with respect to the endless belt moving direction. .   5. The cleaning device according to claim 1, wherein a length of the pressing member in a belt width direction is equal to or greater than a width of the endless belt. 6.   6. The cleaning device according to claim 1, wherein the cleaning unit positions the pressing member with respect to the endless belt after positioning with respect to the opposing roller. .   An intermediate transfer unit comprising a plurality of transfer means and a cleaning device, wherein the cleaning device is the cleaning device according to any one of claims 1 to 6, wherein the cleaning device is included in the plurality of transfer means. The intermediate transfer unit is disposed immediately before the transfer means located on the most upstream side in the belt running direction.   A transfer conveyance unit comprising a plurality of transfer means and a cleaning device, wherein the cleaning device is the cleaning device according to any one of claims 1 to 6, wherein the cleaning device is a member of the plurality of transfer means. A transfer conveyance unit, which is disposed immediately before the transfer means positioned on the most upstream side in the belt running direction.   An image forming apparatus using the intermediate transfer unit according to claim 7.   An image forming apparatus using the transfer conveyance unit according to claim 8.   11. The image forming apparatus according to claim 9, wherein a plurality of transfer nips formed by the plurality of transfer units and a belt contact portion of the pressing member are arranged substantially in a straight line, and are closest to the pressing member. An image forming apparatus, wherein a belt traveling direction between transfer means is substantially parallel to a belt traveling direction between transfer means.

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