JP3919404B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a facsimile machine, and a printer, and more particularly to an image forming apparatus provided with a cleaning device that cleans a belt-like member such as a transfer conveyance belt with a blade-like member. It is.
[0002]
[Prior art]
Conventionally, as this type of image forming apparatus, there is known an image forming apparatus provided with a transfer conveying belt as an endless movable belt member and a cleaning device for cleaning the transfer conveying belt, together with a charging unit, an exposure unit, a developing unit, and the like. It has been. In this image forming apparatus, first, a latent image carrier is uniformly charged by a charging unit, and then an electrostatic latent image is formed on the latent image carrier by image exposure by an exposure unit. The electrostatic latent image is developed by a developing device to form a visible image, and the transfer conveyance belt is formed in a transfer region where the latent image carrier and the transfer conveyance belt face each other by the transfer conveyance means using the transfer conveyance belt. The visible image on the latent image carrier is transferred to the transfer paper to be conveyed. The transfer paper on which the visible image is transferred is conveyed to a fixing unit, and the visible image on the transfer paper is fixed.
[0003]
In the image forming apparatus, it is rare that excessive toner adheres to the transfer conveyance belt. However, when the size of the transfer paper does not match the toner image area on the latent image carrier or when the transfer paper is jammed, the transfer paper remains on the latent image carrier. The toner may be transferred. In addition, a small amount of toner may adhere to the latent image carrier, and the toner may be transferred to the transfer / conveying belt. When toner adheres to the transfer / conveying belt in this way, it is necessary to clean the surface of the transfer / conveying belt and remove the toner on the transfer / conveying belt.
[0004]
As a cleaning device for cleaning the transfer conveyance belt, a device that removes toner on the transfer conveyance belt by bringing a blade-like member into contact with the transfer conveyance belt is generally used. As the contact pressure of the blade-shaped member with respect to the transfer / conveyance belt increases, the cleaning performance for the transfer / conveyance belt also increases. Japanese Patent Application Laid-Open No. 2-33482 discloses a cleaning device that removes toner on a transfer / conveying belt by bringing a blade-shaped member into contact with the transfer / conveying belt from a counter direction. In this cleaning device, the blade-like member is brought into contact with the transfer conveyance belt from the counter direction, so that the contact pressure between the blade-like member and the transfer conveyance belt increases. Accordingly, there is an advantage that the cleaning performance for the transfer / conveying belt is superior to the cleaning device that brings the blade-shaped member into contact with the trailing direction.
[0005]
[Problems to be solved by the invention]
However, if the blade-like member is continuously brought into contact with the transfer-conveying belt that moves endlessly from the counter direction, the contact portion of the blade-like member that is in contact with the transfer-conveying belt is softened due to heat and drowned. There was a fear. In particular, both end portions in the extending direction of the contact portion have a high degree of freedom of deformation, so that the contact portion is easier to bend than the center portion of the contact portion. When both ends are rolled, it becomes a trigger and the central portion of the blade-shaped member is also rolled.
If the blade-like member is rolled in this way, the cleaning performance will be deteriorated and the transfer paper will be stained, and the drive system for driving the transfer conveyance belt will increase and the drive system will be damaged. Cause trouble.
[0006]
It should be noted that various problems due to the sag of the blade-like member are not limited to cleaning the transfer / conveying belt, but can occur in the same manner when cleaning belt-like members other than the transfer / conveying belt. For example, the same problem may occur when cleaning is performed by bringing a blade-shaped member into contact with a belt-shaped member such as a photosensitive belt or an intermediate transfer conveyance belt used in the image forming apparatus from the counter direction.
[0007]
The present invention has been made in view of the above problems, and an object of the present invention is to prevent the blade-like member from coming into contact with the endlessly movable belt-like member from the counter direction and to maintain the cleaning performance. It is an object of the present invention to provide an image forming apparatus that can do this.
[0008]
In order to achieve the above object, the inventions of claims 1 to 3 include a belt-like member that can move endlessly, a roller- like member that stretches and supports the belt-like member, and a position facing the roller-like member In the image forming apparatus having a cleaning device that contacts the belt-like member with the blade-like member from the counter direction for cleaning, both ends of the contact portion of the blade-like member in contact with the belt-like member in the extending direction contact pressure at is what you from smaller Kunar so the contact pressure at the central portion inside than the both end portions of the contact portion.
[0009]
The image forming apparatus of these are the contact pressure in the extending direction end portions of the contact portion in contact with the belt-like member of the blade-like member, the inside of the central portion than the both end portions of the contact portion Therefore, the frictional force at the both end portions is smaller than the frictional force at the central portion while maintaining the contact pressure at the central portion.
[0010]
In particular, in the first aspect of the present invention , a diameter of a portion of the roller-shaped member facing the blade-shaped member facing both ends in the extending direction of the contact portion of the blade-shaped member is at the central portion. The diameter is smaller than the diameter of the facing part.
[0011]
In this image forming apparatus, the diameter of the portion of the blade-shaped member facing both ends of the contact portion in the extending direction is smaller than the diameter of the portion facing the central portion. The distance from the surface of the roller-shaped member facing both ends is greater than the distance between the central portion and the surface of the roller member. Therefore, the contact pressure at the both end portions of the contact portion is smaller than the contact pressure at the central portion of the contact portion. Therefore, while maintaining the contact pressure at the central portion, the frictional force at both ends is smaller than the frictional force at the central portion.
[0012]
According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, of the surface portion of the roller-like member that supports the belt-like member, at both ends in the extending direction of the contact portion of the blade-like member. A groove is provided in the facing portion.
[0013]
In this image forming apparatus, since the groove is provided in the portion of the blade-like member facing both ends in the extending direction of the contact portion, the width of the belt-like member is larger than the width of the contact portion. In addition, it is possible to reduce only the contact pressure at both ends while securing the support at both ends in the width direction of the belt-like member.
[0014]
According to a third aspect of the present invention, the surface of the surface of the roller- shaped member that faces the blade- shaped member that supports the belt-shaped member is opposed to both end portions in the extending direction of the contact portion of the blade-shaped member. An elastic member is used for the portion.
[0015]
In this image forming apparatus, the elasticity of the elastic member provided in the portion of the blade-shaped member facing the both ends in the extending direction of the contact portion can reduce the contact pressure at the both ends. Even if a partial increase in contact pressure occurs at both ends, the increase in the contact pressure can be mitigated by the elasticity of the elastic member.
The elastic member is preferably provided so that the surface of the support when the support supports the belt-like member is uniform. By comprising in this way, when this support body supports this belt-shaped member, the said belt-shaped member can be supported stably.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which the present invention is applied to a laser printer as an image forming apparatus will be described.
FIG. 2 is a schematic configuration diagram of the laser printer according to the present embodiment. This laser printer includes a photosensitive drum 1 as an image carrier, a charger 2 as a charging unit, an exposure unit 3 as an exposure unit, a developing device 4 as a developing unit, a transfer conveyance device 5 as a transfer conveyance unit, and It comprises a photoconductor cleaning device 6 as an image carrier cleaning device. The photosensitive drum 1 is uniformly charged by the charger 2 while being driven to rotate counterclockwise as indicated by an arrow A in the figure, and then subjected to scanning exposure on the basis of image information by the exposure device 3 so that the surface is statically exposed. An electrostatic latent image is formed. This electrostatic latent image is developed with toner at a position facing the developing device 4 and becomes a toner image. The toner image on the photosensitive drum 1 is transferred to a transfer sheet serving as a transfer material that is sent from the registration roller 7 at a predetermined timing at a position facing the transfer conveyance device 5.
[0017]
In the transfer / conveying device 5, a transfer / conveying belt 11 as a belt-like member is supported and stretched by a transfer bias roller 8, a driving roller 9 and a driven roller 10 as supporting members. A transfer nip is formed when the photosensitive drum 1 is in pressure contact with a stretched portion between the transfer bias roller 8 and the driven roller 10 of the transfer conveyance belt 11. The transfer bias roller 8 is located downstream of the transfer nip in the belt moving direction, and applies a charge having a polarity opposite to that of the toner from the back surface of the transfer conveyance belt 11. A belt cleaning device 12 as a cleaning device for removing toner and paper dust on the transfer conveyance belt 11 is provided on the lower surface of the transfer conveyance belt 11 in the vicinity of the driving roller 9. The belt cleaning device 12 includes a cleaning blade 13 as a blade-like member and a holder 14 that supports the cleaning blade.
[0018]
The transfer paper is fed to a registration roller 7 from a paper feeding device (not shown), and sent out from the registration roller 7 in accordance with the toner image on the photosensitive drum 1. This transfer paper is conveyed by the transfer conveyance belt 11, and the toner image on the photosensitive drum 1 is transferred and separated from the transfer conveyance belt 11 at the driving roller 9. Thereafter, the transfer paper is conveyed to a fixing device (not shown), and after the toner image is fixed, it is discharged to the outside. Further, after separating the transfer paper, the photosensitive drum 1 is cleaned by the photosensitive member cleaning device 6 to remove residual toner, and is prepared for the next image forming operation.
[0019]
In the above laser printer, when the size of the toner image on the photosensitive drum 1 and the transfer paper does not match due to the irregular size of the transfer paper, or when the transfer paper is jammed, the photosensitive drum The toner may be transferred from 1 to the transfer conveyance belt 11. In addition, a small amount of toner may adhere to the non-image portion on the photosensitive drum 1 and the toner may be transferred to the transfer conveyance belt 11. Therefore, in the laser printer of this embodiment, the belt cleaning device 12 having the cleaning blade 13 is disposed so as to face the driving roller 9 on the downstream side in the belt moving direction from the transfer paper separating position. The cleaning blade 13 of the belt cleaning device 12 is in contact with the portion of the transfer transport belt 11 supported by the drive roller 9 from the counter direction. After the transfer paper is separated from the transfer conveyance belt 11 by the contact portion of the cleaning blade 13 that is in contact with the transfer conveyance belt 11, foreign matters such as toner on the transfer conveyance belt 11 are removed.
[0020]
However, if the transfer conveyance belt 11 continuously moves while the cleaning blade 13 is in contact with the transfer conveyance belt 11 from the counter direction, the cleaning blade 13 may be softened by heat and the cleaning blade 13 may be rolled. . In particular, both end portions in the extending direction of the contact portion 13a in contact with the transfer conveyance belt of the cleaning blade 13 are easily drowned due to structural factors that have a free end and a large degree of deformation. When the curl occurs at both ends, the curl propagates to the inner central part of the both ends, the cleaning performance is deteriorated by the cleaning blade 13, the backside of the transfer paper is generated, and the transfer is transferred. There is a possibility that various problems such as an increase in driving load for driving the conveyor belt 11 and damage to the driving system may occur.
[0021]
Therefore, in the present embodiment, the contact pressure at both ends in the extending direction of the contact portion 13a of the cleaning blade 13 is configured to be smaller than the contact pressure at the center portion.
[0022]
FIG. 1 is a partial cross-sectional view showing a state in which the cleaning blade 13 is in contact with the surface of the transfer conveyance belt 11 as seen from the moving direction of the transfer conveyance belt 11. In FIG. 1, the horizontal axis indicates the distance from one end of the cleaning blade 13 in the extending direction of the contact portion 13a, and the contact pressure [N / mm] between the transfer conveyance belt 11 and the cleaning blade 13 per unit width is expressed in the vertical direction. A graph with axes is also shown. In this embodiment, a V-shaped groove 9 a is formed in the surface portion of the driving roller 9 where both ends of the contact portion 13 a of the cleaning blade 13 are opposed to each other. By forming the V-shaped groove 9a, the diameter of the driving roller 9 in the region having the V-shaped groove 9a is smaller than the diameter of the other portion not having the groove 9a. At this time, the contact pressure at both ends in the extending direction of the contact portion 13a of the cleaning blade 13 is smaller than the contact pressure at the central portion where foreign matters such as toner adhere to the inside of the both ends and are likely to get dirty.
[0023]
As described above, according to the present embodiment, the contact pressure at both end portions of the contact portion 13a of the cleaning blade 13 is smaller than the contact pressure at the central portion, so that friction acts between the both end portions and the transfer conveyance belt 11. The force is smaller than the frictional force with the central portion. Therefore, it is possible to suppress the wrinkles at both ends of the contact portion 13a of the cleaning blade 13, and to secure a predetermined contact pressure at the central portion where foreign matters such as toner adhere and become dirty, thereby deteriorating the cleaning performance. I will not let you. Accordingly, it is possible to prevent the cleaning blade 13 from curling and to exhibit stable cleaning performance.
[0024]
In the above embodiment, instead of forming the groove 9a in the drive roller 9, as shown in FIG. 3, from the inside of the position facing both ends of the contact portion 13a of the cleaning blade 13 to the end of the roller 9 The diameter may be smaller than the other area of the roller 9. In FIG. 3, as in FIG. 2, a graph showing a change in contact pressure per unit width between the transfer conveyance belt 11 and the cleaning blade 13 near both ends of the contact portion 13 a of the cleaning blade 13. Is also shown. In the modification shown in FIG. 3, the driving roller 9 has a diameter from the inside to the end in the vicinity of the position supporting the transfer conveyance belt 11 with which both ends of the contact portion 13a of the cleaning blade 13 abut (9b in FIG. 3). However, it has a smaller diameter than the central part. Due to the reduced diameter portion 9b of the drive roller 9, the contact pressure in the vicinity of both ends becomes smaller than the contact pressure in the central portion as shown in the graph shown in FIG. Accordingly, since the frictional force at the both end portions is smaller than the frictional force at the central portion, the force for dripping both end portions of the contact portion 13a of the cleaning blade 13 is reduced.
[0025]
Further, in the above-described embodiment, the surface of the driving roller 9 from the inside to the end near the position facing both ends of the cleaning blade 13 may be provided with elasticity. FIG. 4 shows a modification in which the surface portion of the drive roller 9 from the position facing both ends of the contact portion 13a of the cleaning blade 13 to the end portion is formed of an elastic member. The driving roller 9 shown in FIG. 4 has elasticity at the surface portion from the portion facing the both end portions of the contact portion 13a of the cleaning blade 13 to the end portion thereof, so that both end portions of the contact portion 13a of the cleaning blade 13 are elastic. The contact pressure with the transfer conveyance belt 11 is relieved. Accordingly, the frictional force acting on the contact surface between the both ends of the cleaning blade 13 and the transfer / conveying belt 11 is smaller than the frictional force acting on the contact surface between the central portion and the transfer belt 11, thereby preventing the cleaning blade 13. it can. Further, even when a partial increase in contact pressure occurs at both ends of the cleaning blade 13, the increase in the contact pressure can be mitigated by the elasticity.
[0026]
In the example of FIG. 4, it is desirable to provide the elastic member 15 so that there is no step on the support surface (outer peripheral surface) of the drive roller 9. As the elastic member 15, for example, chloroprene rubber can be used. By adjusting the thickness and elasticity of the chloroprene rubber, it is desirable that the diameter of the portion where the chloroprene rubber is provided and the other portion are the same when the transfer / conveying belt 11 is stretched. With this configuration, when the transfer conveyance belt 11 is driven, the contact area between the transfer conveyance belt 11 and the driving roller 9 is maintained. Therefore, it is possible to satisfy the cleaning property of the cleaning blade 13 while maintaining the driving property of the transfer / conveying belt 11.
[0027]
In the above-described embodiment, the roller member with which the cleaning blade abuts is the drive roller 9. However, other roller members such as the bias roller 8 and the driven roller 10 can be applied.
[0028]
In the above embodiment, the support member for supporting the transfer conveyance belt 11 is a roller-shaped member. However, the support member that faces the cleaning blade 13 and maintains the adhesion between the transfer conveyance belt 11 and the cleaning blade 13 is used. If so, for example, a planar support may be used.
[0029]
In the above-described embodiment, the belt cleaning device has been described as the cleaning device. However, the present invention may be a cleaning device that cleans a belt-like member such as a photosensitive belt or an intermediate transfer conveyance belt using a blade-like member. If applicable.
[0030]
【The invention's effect】
According to the first to third aspects of the present invention, the frictional force at the both end portions is smaller than the frictional force at the central portion while maintaining the contact pressure at the central portion of the blade-shaped member. It is possible to prevent the both ends from curling and to maintain the cleaning performance at the center of the blade-shaped member.
[0031]
In particular, according to the first aspect of the present invention, the blade-like member is prevented from twisting with a simple configuration in which the diameter of the portion of the roller-like member that opposes both ends of the contact portion in the extending direction is reduced. In addition, the cleaning performance of the blade-like member can be maintained.
[0032]
In particular, according to the invention of claim 2 , since only the contact pressure at the both ends of the blade-like member can be reduced, the contact at both ends of the belt-like member is ensured while ensuring the support at both ends in the width direction. There is an effect that only the pressure can be accurately reduced.
[0033]
In particular, according to the invention of claim 3 , even when a partial increase in contact pressure occurs at both ends of the blade member, the increase in the contact pressure can be mitigated by the elasticity of the elastic member. There is.
[Brief description of the drawings]
FIG. 1 is a partial cross-sectional view showing a state in which a cleaning blade is in contact with a surface of a transfer conveyance belt at a position facing a driving roller of a laser printer according to an embodiment of the present invention.
FIG. 2 is an overall view showing a schematic configuration of the laser printer.
FIG. 3 is a partial cross-sectional view illustrating a state in which a cleaning blade is in contact with a surface of a transfer conveyance belt at a position facing a driving roller according to a modification.
FIG. 4 is a partial cross-sectional view showing a state where a cleaning blade is in contact with the surface of a transfer conveyance belt at a position facing a driving roller according to another modification.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Charging device 3 Exposure device 4 Developing device 5 Transfer conveyance device 6 Photoconductor cleaning device 7 Registration roller 8 Bias roller 9 Driving roller 10 Driven roller 11 Transfer conveyance belt 12 Belt cleaning device 13 Cleaning blade 13a Contact of cleaning blade Part 14 holder 15 elastic member

Claims (3)

A belt-like member that can move endlessly, a roller- like member that stretches and supports the belt-like member, and a blade-like member that contacts the belt-like member from the counter direction at a position facing the roller-like member for cleaning In an image forming apparatus having a cleaning device
The diameter of the part of the roller-shaped member facing the blade-shaped member facing the both ends in the extending direction of the contact portion of the blade-shaped member contacting the belt-shaped member is set to is made smaller than the diameter of the portion facing the central portion of the inner side than both ends, the contact pressure at the both ends, characterized in that the from smaller Kunar so the contact pressure in the intermediate central portion Image forming apparatus . The image forming apparatus 請 Motomeko 1,
Of the surface portion of the roller-like member that supports the belt-like member, a groove is provided in a portion of the blade-like member that faces both ends in the extending direction of the contact portion. Forming equipment. A belt-like member that can move endlessly, a roller-like member that stretches and supports the belt-like member, and a blade-like member that contacts the belt-like member from the counter direction at a position facing the roller-like member for cleaning In an image forming apparatus having a cleaning device
The surface of the surface of the roller-shaped member that supports the belt-shaped member facing the blade-shaped member is opposed to both ends in the extending direction of the contact portion of the blade-shaped member that is in contact with the belt-shaped member. to and are part, in Rukoto using resilient members, contact pressure at the both ends, the image forming apparatus is characterized in that set to be smaller than the contact pressure at the central portion.

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