1. Field of the Invention
The present invention relates to an image forming apparatus and a process cartridge.
The image forming apparatus is defined here as the one that forms an image on a recording medium. For example, the image forming apparatus includes an electrophotographic copying machine, an electrophotographic printer (a light emitting diode (LED) printer and a laser beam printer), an electrophotographic facsimile machine, and an electrophotographic word processor using an electrophotographic image forming process.
The recording medium is the one on which the image is formed, and refers to a recording sheet and an over head projector (OHP) sheet, for example.
The process cartridge refers to the one that can be attached to and detached from a main body of the image forming apparatus.
2. Description of the Related Art
Heretofore, the image forming apparatus has adopted a process cartridge system which integrates an electrophotographic photosensitive member (hereinafter referred to as photosensitive drum) as an image carrying member with a process unit acting thereon, and which can be attached to and detached from the main body of the image forming apparatus (hereinafter referred to as apparatus main-body). The process cartridge system can improve operability because the maintenance of the apparatus can be performed by a user itself.
The process cartridge adopts a corona discharge system or a roller charging system as an example of a charging unit (a charging member or a charging device) for charging the photosensitive drum. The corona discharge system uses a charging wire to generate corona discharge for uniformly discharging a surface of the photosensitive drum. A large number of configurations have been proposed in which a cleaning member is provided as a means of periodically cleaning dirt attached on the charging wire and is moved in a longitudinal direction along the charging wire.
However, if the cleaning member is left in an image forming area in the longitudinal direction at the time of forming an image, the cleaning member covers the wire. In other words, the cleaning member inhibits the wire from charging the photosensitive drum to cause an image defective due to a charging defective. Japanese Patent Application Laid-Open No. 2002-304046, for example, discusses a configuration, as a means of solving the above problem, in which leaving the cleaning member in the image forming area prevents the process cartridge from being attached to the apparatus main-body.
The present invention develops the above conventional example.
According to an aspect of the present invention, an image forming apparatus configured to form an image on a recording medium in which an apparatus main-body to and from which a process cartridge can be attached and detached is provided. The process cartridge includes an image carrying member configured to carry an image, a charging member configured to charge the image carrying member, a cleaning member configured to clean the charging member by contacting the charging member, and a force receiving unit configured to receive a force for moving the cleaning member in a longitudinal direction of the image carrying member. The apparatus main-body includes a slope portion which slopes in a direction in which the process cartridge is attached and contacts the force receiving unit to apply the force in the process where the process cartridge is attached to the apparatus main-body, and, in a case where a region where an image can be formed on the image carrying member is taken as an image forming region, the slope portion applies the force to the force receiving unit to move the cleaning member from the inside to the outside of the image forming region.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Various exemplary embodiments, features, and aspects of the invention will be described in detail below with reference to the drawings.
A configuration of an image forming apparatus is described below with reference to
The following description is made in a direction in which a user using the image forming apparatus views. In
The image forming apparatus includes an apparatus main-body 2 and a process cartridge 5 that is attachable to and detachable from the apparatus main-body 2. As illustrated in
The paper feeding unit 3 is provided in the lower portion of the apparatus main-body 2 and includes a paper feed tray 7 and a paper feeding roller 8. Each sheet of papers stored in the paper feed tray 7 is fed by the paper feeding roller 8 into the process cartridge 5 (between a photosensitive drum 9 and a transfer roller 10).
The exposure device 4 is provided in the upper portion of the apparatus main-body 2. In the exposure device 4, laser beams based on image data and emitted from a laser emitting unit 11 are scanned at a high speed on a surface of the photosensitive drum 9 being an image carrying member to expose the surface of the photosensitive drum 9.
The configuration of the process cartridge which is a characterizing portion of the present invention is described below with reference to
As illustrated in
The process cartridge 5 includes the photosensitive drum 9, a charging device 13, a developing roller 14 being a developer carrying member, a layer thickness regulating member 15, a developer storage unit 16 for storing a developer, a developer opening portion 17, and a conveyance member 18 for stirring and conveying the developer.
In the thus configured process cartridge 5, the surface of the photosensitive drum 9 is uniformly charged by the charging device 13 and then exposed by laser beams scanned at a high speed from the exposure device 4 (illustrated in
The developer carried on the developing roller 14 is supplied to the electrostatic latent image (latent image) formed on the photosensitive drum 9 from the developing roller 14. Thus, the electrostatic latent image is developed by the developing roller 14, and images (toner images or developer images) are formed by toner on the surface of the photosensitive drum 9. In other words, the photosensitive drum 9 is an image carrying member which carries the image. Thereafter, a sheet is conveyed between the photosensitive drum 9 and the transfer roller 10 to transfer the developer image on the photosensitive drum 9 to the sheet.
The image forming region L is equal to or smaller than the developer supply area H in width. The toner is moved to the latent image formed in the image forming region L of the photosensitive drum 9 from the developer supply area H of the developing roller 14 to develop the latent image, thereby forming a toner image. In other words, the image forming region L is a region where an image (a toner image) can be formed on the photosensitive drum 9.
The charging device 13 is described below with reference to
As illustrated in
The charging wire 20 is formed of a thin wire of tungsten or stainless steel, and is a metallic wire stretched in the longitudinal direction. As illustrated in
When the charging wire 20 becomes dirty, the user detaches the process cartridge 5 from the apparatus main-body 2, and moves the holding member 23 in the longitudinal direction to allow the cleaning member 22 to wipe away the dirt on the charging wire 20. In other words, the holding member 23 is a force receiving unit for receiving force, from the outside, for moving the cleaning member 22. The cleaning member 22 moves together with the holding member 23 in the longitudinal direction.
As illustrated in
In the charging device 13 thus configured, a high voltage power supply (not illustrated) applies voltage between the charging wire 20 and the grid electrode 21 to generate corona discharge between the charging wire 20 and the grid electrode 21. Air around the charging wire 20 is ionized to generate ions. The ions serve to charge the periphery of the photosensitive drum 9.
The process cartridge 5 is inserted into the thus configured apparatus main-body 2 along the first and second insertion guide faces 26a and 26b, and the first guided portion 27a is fitted into the cylindrical face 26c to complete attachment.
In other words, the slope 28a is a slope portion which slopes in the attachment direction in which the process cartridge 5 is attached to the apparatus main-body 2. Both the right and the left of the slope 28a extend beyond the image forming region L. The holding member 23 of the process cartridge 5 is provided with a contact surface 23a which contacts the slope 28a.
If the process cartridge 5 whose holding member 23 is kept remained in the image forming region L is inserted (attached) to the thus configured apparatus main-body 2, as illustrated in
As illustrated in
The configuration of the foregoing present exemplary embodiment is summarized below. The image forming apparatus according to the present exemplary embodiment includes the process cartridge 5 that is attachable to and detachable from the apparatus. The process cartridge 5 includes the photosensitive drum (the image carrying member) 9 for carrying an image (a toner image) and the charging device (the charging member) 13 for charging the photosensitive drum 9. The process cartridge 5 further includes the cleaning member 22 which contacts the charging wire 20 configuring the charging device 13 to clean the charging wire 20 and the holding member (the force receiving unit) 23 for receiving force for moving the cleaning member 22.
The apparatus main-body 2 includes the slope (the slope portion) 28a which slopes in the attachment direction where the process cartridge 5 is attached to the apparatus main-body 2. The process cartridge 5 is attached to the apparatus main-body 2 with the holding member 23 arranged in the image forming region L to contact the holding member 23 with the slope 28a in the process of attachment. According to a movement of the process cartridge 5, the holding member 23 moves to the outside in the longitudinal direction of the photosensitive drum 9. Furthermore, according to such movement of the holding member 23, the cleaning member 22 also moves to the outside in the longitudinal direction to retract into a region (a retract region 25) outside the image forming region L.
In other words, force is applied to the holding member 23 provided on the cleaning member 22 to cause the slope 28a to move the cleaning member 22 to the outside in the longitudinal direction.
Because the cleaning member 22 lies in the outside the image forming region L in a case where the process cartridge 5 is attached to the apparatus main-body 2, the cleaning member 22 never prevents the charging device 13 (the charging wire 20) from charging at the time of forming images. The charging device 13 is inhibited from causing a charge defective to inhibit also an image defective from being caused on an image formed by the image forming apparatus. The user has only to attach the process cartridge 5 thereto to move the cleaning member 22 to the outside of the image forming region L. This can reduce a burden to the user.
Modification examples of the contact member 28 are described below with reference to
As illustrated in
The two slopes 28c move the holding member 23 (the cleaning member 22) in the opposite directions (different directions) when contacting the holding member 23. One of the two slopes 28c provided on the left side moves the holding member 23 (the cleaning member 22) to the left side. The other of the two slopes 28c provided on the right side moves the holding member 23 (the cleaning member 22) to the right side.
In the aforementioned exemplary embodiment and modification examples, the contact member 28 (the slopes 28a, 28b, and 28c) is provided all over the image forming region in the longitudinal direction. However, as illustrated in
In the present modification example, the contact members 28 are provided only on both sides in the longitudinal direction, but not at the center in the longitudinal direction.
The present modification example is also configured such that the user inserts the process cartridge 5 into the apparatus main-body 2 to cause the slopes 28d to move the holding member 23 and the cleaning member 22 to the outside of the image forming region L. In this case, the standby areas 25 of the holding member 23 and the cleaning member 22 are provided on both sides outside the image forming region L in the longitudinal direction as in the case of
Also in the configuration of the above modification examples, the holding member 23 and the cleaning member 22, which lie in the image forming region L, can be moved to the standby area 25 outside the image forming region L while the process cartridge 5 is being inserted into the apparatus main-body 2. In other words, the holding member 23 and the cleaning member 22 can be moved to the outside of the image forming region L by the slopes 28b, 28c, and 28d of the contact member 28. This allows preventing the occurrence of an image defective due to a charge defective. The effects of the configuration described in
The moving amount of the cleaning member 22 is smaller in
In the configuration of
That is, in the configuration of
In the configuration of
In the configuration of
However, the possibility that the cleaning member 22 is left at the center portion of the image forming region L is comparatively small. In most cases, it seems that the cleaning member 22 is left in the image forming region L when the user cannot move it sufficiently to the outside of the region in the longitudinal direction. That is, in that case, the cleaning member 22 is positioned at the end portions of the image forming region L, so that the slopes 28d are merely arranged only on both sides of the image forming region L to allow the cleaning member 22 to be moved to the standby area 25 in most cases.
In
It is also recommendable that the control unit 31 causes a display provided on the image forming apparatus 1 or a monitor of a computer 50 connected with the image forming apparatus 1 to display that an image cannot be formed or the cleaning member 22 needs to be moved to the standby area 25.
Alternatively, in a case where the cleaning member 22 is arranged at the region G where the slopes 28d are not arranged (the center portion of the image forming region L), the holding member 23 may be caused to collide with the apparatus main-body 2 to prevent the process cartridge 5 from being attached to the apparatus main-body 2.
The attachment inhibition unit 29 is provided to contact the holding member 23, however, the attachment inhibition unit 29 is configured to collide with the cleaning member 22, which prevents the process cartridge 5 from being moved (attached).
As described above, the configuration of the slope can be selected as required, as illustrated in
The present exemplary embodiment has described above the configuration in which the cleaning member 22 and the holding member 23 are separate members, and the cleaning member 22 is fixed to the holding member 23. However, from the viewpoint of cost reduction, even if the cleaning member 22 is integrated with the holding member (the force receiving unit) 23, an equivalent effect can be achieved. In other words, a portion of the cleaning member 22 may be the force receiving unit for contacting the contact member 28.
The cleaning member 22 is a member for cleaning the charging wire 20 of the charging member. However, the cleaning member 22 may be a member for cleaning the grid electrode 21.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2014-012729 filed Jan. 27, 2014, which is hereby incorporated by reference herein in its entirety.
Number | Date | Country | Kind |
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2014-012729 | Jan 2014 | JP | national |