Patent Application
20130064568
The present invention relates to a process cartridge used in an electrophotographic image forming apparatus.
Here, the electrophotographic image forming apparatus forms an image on a recording material (medium) by using an electrophotographic image forming process. Examples of the image forming apparatus may include a printer (LED printer, laser beam printer or the like), a copying machine, a facsimile machine, a word processor and a multi-function machine (multi-function printer or the like) of the these machines.
In the image forming apparatus such as the printer using the electrophotographic process, a drum-like electrophotographic photosensitive member (hereinafter referred to as a photosensitive drum) which is an image bearing member is electrically charged uniformly and is subjected to selective exposure to light to form a latent image. Then, the latent image is visualized (developed) with a toner as a developer, and a resultant toner image is transferred onto a recording material. Then, the transferred roller image is subjected to application of heat and pressure to be fixed on the recording material, so that image recording (image formation) is effected.
Such an apparatus is subjected to toner supply or maintenance of various process means. For this reason, as a means for facilitating a toner supplying operation or the maintenance, a process cartridge prepared by integrally assembling the photosensitive drum, a charging means, a developing means, a cleaning means and the like in a frame has been put into practical use.
According to this process cartridge type, the maintenance of the apparatus can be performed by a user himself (herself), so that operativity can be remarkably improved. Therefore, the process cartridge type has been widely used in the image forming apparatus.
Further, in recent years, a color image forming apparatus for forming a color image by using develops of a plurality of colors has been popularized. As the color image forming apparatus, an in-line type image forming apparatus in which photosensitive drums corresponding to image forming operations using toners of the plurality of colors are disposed in line along a surface movement direction of a toner image receiving member onto which the toner image is to be transferred has been known.
In the color image forming apparatus of the in-line type, there is an apparatus in which the plurality of photosensitive drums are disposed in line with respect to a direction (e.g., a horizontal direction) crossing the vertical direction (the direction of the gravitation). The in-line type is a preferably image forming type in terms of easy response to demands such as speed-up of an image forming speed and development to a multi-function printer.
In the process cartridge, in general, a developing device frame for supporting the developing means is provided with a developing roller, as the developing means, including a metal shaft and an electroconductive rubber member, and a developing blade as a developer regulating member. Further, on a side surface of the developing device frame, a gear train for rotationally driving the developing roller and an electroconductive member for applying a bias (voltage) to the developing roller are provided. In the process cartridge including such an electroconductive member, in order to stably effect application of a developing bias voltage to the rotationally driven developing roller, a constitution in which the electroconductive member is contacted to an end surface of the metal shaft of the developing roller has been proposed (U.S. Pat. No. 8,155,553).
Further, in general, in order to supply the bias from an image forming apparatus main assembly to the process cartridge, a contact member is provided to the process cartridge and is contacted to a main assembly (-side) electric contact provided to the apparatus, so that the bias is applied. In this case, in order to supply a stable bias, the contact member is required to receive a predetermined contact (point) pressure from the main assembly electric contact. For that reason, there was a conventional constitution in which a limiting member for limiting movement of the contact member is provided in a back side of the contact member (U.S. Pat. No. 6,934,485).
However, as described above, in the constitution in which the contact member receives the contact pressure from the main assembly electric contact and thus the bias is applied, there is the case where it is difficult to dispose the limiting member for limiting movement of the contact member in the back side of the contact member.
A principal object of the present invention is to provide a process cartridge capable of limiting movement of a contact member even in the case where it is difficult to dispose a limiting for limiting movement of the contact member in a back side of the contact member.
This object is accomplished by a process cartridge according to the present invention.
According to an aspect of the present invention, there is provided a cartridge detachably mountable to a main assembly of an image forming apparatus having a main assembly electric contact, the cartridge comprising: a contact member for receiving pressure by the main assembly electric contact, wherein the contact member has a first surface as a contact portion for receiving the pressure by the main assembly electric contact and has a second surface bent from the first surface toward a side opposite from a side where the main assembly electric contact is provided; a holding member for holding the contact member; a portion to be prevented provided at an end of the second surface; and a limiting portion, provided on the holding member, for limiting movement of the portion to be limited.
These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings.
The process cartridge according to the present invention will be described specifically with reference to the drawings.
In the following description, the image forming apparatus main assembly 100A refers to an apparatus constituent portion excluding the process cartridge P.
In the apparatus main assembly 100A, a plurality of process cartridges, i.e., in this embodiment, first to fourth portions P (PY, PM, PC, PK) are juxtaposed in the horizontal direction. Thus, by arranging the plurality of process cartridges P in the horizontal direction, a height of the image forming apparatus can be suppressed. The respective cartridges P have the same electrophotographic process mechanism but are different in color of an associated developer (toner) T and in an amount of the toner T. To each cartridge P, a rotational driving force is transmitted from the apparatus main assembly 100A. Further, to each cartridge P, biases (charging bias voltage, developing bias voltage, and the like) are supplied (not shown) from the apparatus main assembly 100A.
As shown in
In
Below each of the cartridges P (PY, PM, PC, PK), a laser scanner unit LB as an exposure means is disposed. The laser scanner unit LB outputs laser light L correspondingly to image information. The surface of the photosensitive drum 1 is subjected to scanning exposure to the laser light L.
On each of cartridges P (PY, PM, PC, PK), an intermediary transfer belt unit 12 as a primary transfer member is disposed. This intermediary transfer belt unit 12 includes a flexible endless transfer belt 5 and rollers, for stretching and rotating the transfer belt 5, consisting of a driving roller 51, a secondary transfer opposite roller 52 and a follower roller 53. The photosensitive drum 1 of each cartridge P is contacted to the transfer belt 5 at its upper surface. A contact portion N1 between the photosensitive drum 1 and the transfer belt 5 is a primary transfer portion. Inside the transfer belt 5, primary transfer rollers 8 are disposed opposed to the associated photosensitive drums 1. At a position opposing the secondary transfer opposite roller 52, a secondary transfer roller 9 as a secondary transfer means is disposed. A contact portion N2 between the transfer belt 5 and the secondary transfer roller 9 is a secondary transfer portion.
Below the lower scanner unit LB, a sheet feeding unit 31 is disposed. The sheet feeding unit 31 includes a tray 32 in which sheets of the recording material S are stacked and accommodated and includes a sheet feeding roller group 33, and the like.
In an upper right side of the apparatus main assembly 100A, a fixing unit 10 is disposed. An upper surface 100a of the apparatus main assembly 100A constitutes a sheet discharge tray.
An operation for forming a full-color image is as follows.
The photosensitive drums 1 of the first to fourth cartridges P (PY, PM, PC, PK) are rotationally driven in an arrow A direction at a predetermined speed. The transfer belt 5 is rotationally driven in an arrow B direction (codirectionally with the photosensitive drums at their contact portions) at a speed corresponding to the speed of the photosensitive drums 1. The laser scanner unit LB is also driven.
In synchronism with the drive of the laser scanner unit LB, the surface of the photosensitive drum 1 of each cartridge P is uniformly charged to a predetermined polarity and a predetermined potential by the charging roller 2. The laser scanner unit LB scans and exposes the surface of each photosensitive drum 1 with the laser light L depending on an image signal for an associated color. As a result, an electrostatic latent image depending on the image signal for the associated color is formed on the surface of each photosensitive drum 2. The thus formed electrostatic latent image is developed by the developing roller 17 rotationally driven in an arrow D direction at a predetermined speed.
By the above-described electrophotographic image forming process operation, on the photosensitive drum 1 of the first cartridge PY, a yellow (Y) toner image corresponding to a yellow component of a full-color image is formed. Then, the Y toner image is primary-transferred onto the transfer belt 5.
Similarly, the toner images of the second cartridge PM, the third cartridge PC and the fourth cartridge PK are superposed on the transfer belt 5, so that unfixed toner images for a four color-based full-color image are formed. In each cartridge P, a transfer residual toner remaining on the surface of the photosensitive drum 1 after the primary transfer is removed by the cleaning blade 6.
On the other hand, with predetermined control timing, the recording material S is separated and fed one by one. The recording material S is introduced into the secondary transfer nip N2, with predetermined control timing, as a contact portion between the secondary transfer roller 9 and the transfer belt 5. As a result, in a process in which the recording material P is conveyed through the secondary transfer nip N2, the respective color toner images superposed on the transfer belt 5 are collectively transferred onto the surface of the recording material S.
The recording material S is then separated from the surface of the transfer belt 5 and then is introduced into the fixing unit 10. Then, the recording material S is heated and pressed at a fixing nip. As a result, the toner images are fixed on the recording material S. Thereafter, the recording material S comes out of the fixing device 10 and is discharged, as a full-color image-formed product, onto the upper surface 100a of the apparatus main assembly 100A.
In this embodiment, the first to fourth cartridges P (PY, PM, PC, PK) have, as described above, the same electrophotographic process mechanism but are different in color of accommodated toner and in amount of the toner.
As shown in
Each cartridge P includes the cleaning unit 13 and the developing unit 14.
As shown in
The photosensitive drum 1 is, as shown in
A driving force of a driving motor (not shown) of the apparatus main assembly 100A is transmitted to the photosensitive drum 1, so that the photosensitive drum 1 is rotationally driven in the arrow A direction at the predetermined speed as shown in
The charging roller 2 is a charging member of a contact charging type in which it rotated by the rotation of the photosensitive drum 1 in contacted with the photosensitive drum 1. To the cleaning frame 14, as shown in
Here, the charging roller supporting members 15 (15R, 15L) are, as shown in
Further, the charging roller supporting members 15 (15R, 15L) are urged toward the photosensitive drum 1 by urging members 16 (16R, 16L) as an urging means.
As shown in
On the other hand, referring to
As shown in
In this embodiment, the developing roller 17 is disposed in contact with the photosensitive drum 1 but may also be disposed close to the photosensitive drum 1 with a predetermined gap.
In the developing unit 4, a developer supplying roller 20 as a developer supplying member rotating in an arrow E direction (counterclockwise direction) indicated in
Referring to
As shown in
A predetermined bias is applied from a power source (not shown) in the image forming apparatus to the developing roller 17. As a result, the toner conveyed to the developing roller 17 is deposited on the electrostatic latent image at the developing portion as the contact between the developing roller 17 and the photosensitive drum 1, thus developing the electrostatic latent image into the toner image.
In the process cartridge P, a means for applying the bias to the developing roller 17 provided in the developing unit 4 and a constitution of the contact (point) will be described specifically.
Referring to
The contact member 27 provided to the process cartridge P contacts a main assembly electric contact 11 provided to the apparatus main assembly 100A to receive predetermined pressure, so that the bias is applied. The applied bias is supplied to the developing roller 17 via the urging member 30 and the energization member 29. The urging member 30 urges the developing roller 17 in the rotational axis direction and has the pressure necessary to perform stable bias application to the developing roller 17 which is rotationally driven. The energization member 29 slides on the metal shaft 17a of the developing roller 17 by the rotational drive of the developing roller 17 while urging the developing roller 17 by an urging force of the urging member 30.
Here, the contact member 27 is, in order to supply a stable bias to the developing roller 17, required to receive stable contact pressure from the main assembly electric contact 11. For that reason, there is a need to support the contact pressure applied from the main assembly electric contact 11 to the contact member 27.
This will be described with reference to
The contact member 27 is bent from the first surface 27a toward a side opposite from the main assembly electric contact 11, i.e., an opposite side of the contact point, thus forming bent portions 27d and 27e.
As a result, the contact member 27 has a second surface 27b formed by the bending for the bent portion 27d and a fourth surface 27f formed by the bending for the bent portion 27e. Further, the contact member 27 has a third surface 27h formed from a bent portion 27g formed by bending the contact member 27. That is, the contact member has the third surface 27h formed in a side opposite from the second surface 27b.
The second surface 27b of the contact member 27 is positioned along a holding wall 24c formed as a part of the holding member 24 and includes a portion to be limited 27c at its end. Further, the fourth surface 27f extends toward the inside of the holding member 24, and the third surface 27h is positioned along an inner surface of the side wall 24b of the holding member 24.
The third surface 27h of the contact member 27 is provided with a hole 27i (
In this case, at a contact portion between the contact member 27 and the urging member 30, the urging force of the urging member 30 and reaction force of the holding member 24 are balanced with each other, so that the contact member 27 is held by the holding member 24. That is, the third surface 27h is urged by the urging member 30 and thus the contact member 27 is held by the holding member 24. Further, when the contact pressure by the main assembly electric contact 11 acts on the contact member 27, the portion to be limited 27c is contacted to a limiting portion 24f provided on the holding wall 24c, so that movement of the portion to be limited 27c in a contact pressure direction by the main assembly electric contact 11 is limited.
A method of assembling the contact member 27, the urging member 30 and the energization member 29 with the holding member 24 will be described.
As shown in
As described above, even when the contact pressure by the main assembly electric contact 11 acts on the contact member 27, the movement of the contact member 27 is limited by the limiting portion 24f provided to the holding member 24. For that reason, even when a limiting member for limiting the movement of the contact member 27 is not disposed in a back side of the contact portion 27h, stable contact pressure can be received.
That is, according to the present invention, in the constitution in which the contact member receives the contact pressure from the main assembly electric contact and thus the bias is applied, even in the case where it is difficult to dispose the limiting member, for limiting the movement of the contact member, in the back side of the contact member, it is possible to limit the movement of the contact member. That is, according to the present invention, the movement of the contact member by the contact pressure can be limited by providing the limiting portion to the holding member and therefore even when the limiting member for limiting the movement of the contact member is not disposed, stable contact pressure can be received.
Next, another embodiment according to the present invention will be described with reference to
Referring to
Also in this embodiment, similarly as in Embodiment 1, the contact members 27A is provided with a portion to be limited 27c. A method of assembling the contact member 27A, the urging member 30 and the energization member 29 with the holding member 24 will be described.
As shown in
As described above, by providing the contact member 27A with the cut-away portion 28e and the guide portion 28f, as shown in
In Embodiments 1 and 2, the contact constitution of the bias application to the developing roller 11 and the urging constitution in the longitudinal direction are described but as another embodiment, similar constitutions may also be employed for the charging roller 2, the supplying roller 20 and the like. That is, the similar constitutions can also be employed even as a constitution of energization to the process means (the charging roller or the supplying roller) provided in the cartridge.
While the invention has been described with reference to the structures disclosed herein, it is not confined to the details set forth and this application is intended to cover such modifications or changes as may come within the purpose of the improvements or the scope of the following claims.
This application claims priority from Japanese Patent Application No. 201208/2011 filed Sep. 14, 2011, which is hereby incorporated by reference.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2011-201208 | Sep 2011 | JP | national |
