Patent Application
20170108828
Aspects of the present invention relate to a process cartridge and to an image forming apparatus including the same.
The process cartridge is obtained by integrally forming a photosensitive drum and a process unit that performs a process on the photosensitive drum into a cartridge, and can be detachably attached to an image forming apparatus main body.
For example, the photosensitve drum and at least one of a development unit, a charging unit, and a cleaning unit serving as the process units may be integrally formed into a cartridge. The image forming apparatus (electrophotographic image forming apparatus) forms an image on a recording medium through electrophotography.
Examples of the image forming apparatus include an electrophotographic copying machine, an electrophotographic printer (such as a light emitting diode (LED) printer and a laser beam printer), a fax machine, a word processor, and the like.
In an image forming apparatus, a photosensitive drum is uniformly charged. The photosensitive drum is an electrophotographic photosensitive member that generally has a drum shape and serves as an image carrier. Then, the charged photosensitive drum is selectively exposed, so that an electrostatic latent image (electrostatic image) is formed on the photosensitive drum. The electrostatic latent image formed on the photosensitive drum is developed with toner as a developer to be a toner image. The toner image formed on the photosensitive drum is transferred onto a recording material such as a recording sheet or a plastic sheet. The toner image transferred on the recording material is heated and pressed, whereby the toner image is fixed on the recording material in this manner, image recording is performed.
Such an image forming apparatus usually requires toner replenishment and maintenance for various process units. A process cartridge has been commercially used so that the toner replenishment and the maintenance can be easily performed. The process cartridge is obtained by providing the photosensitive drum, the charging unit, the development unit, the cleaning unit, and the like in a frame to form a cartridge, and can be detachably attached to the image forming apparatus main body.
Such a process cartridge system enables a user to perform maintenance for the apparatus without a professional help, and thus can achieve large improvement in operability, so that an image forming apparatus with excellent usability can be provided. Thus, many image forming apparatuses employ the process cartridge system.
In one generally known configuration of the process cartridge, a photosensitive unit and a development device unit are coupled to each other with a coupling member. The photosensitive unit holds the photosensitive drum, the cleaning unit, and the like. The development device unit holds a development unit such as a developing roller.
In the process cartridge, the development device unit is held in such a manner as to be rotatable, relative to the photosensitive unit, about a rotational axis. The development device unit is biased toward the photosensitive unit by its own weight and pressing force from a pressing member such as a spring and from the outside.
The development device unit is biased toward the photosensitive drum in the photosensitive unit, with gap maintaining members in between. The gap maintaining members are attached to both end portions of the developing roller in the axial direction.
The gap maintaining members, attached to both end portions of the developing roller in the axial direction, are in contact with the photosensitive drum while receiving a certain amount of pressing force therefrom.
Thus, a minute gap that can be constantly kept to be the same is provided between the photosensitive drum and the developing roller, whereby an image with excellent image quality can be stably output (Japanese Patent Application Laid-Open No. H08-339149).
The present disclosure of the invention is an improved version of the configuration described above. More specifically, a development device unit is biased toward a photosensitive unit, with pressing force more balanced between gap maintaining members that are on both end portions of a developing roller in the axial direction and come into contact with the photosensitive drum.
A process cartridge according to one aspect of the present invention that is detachably attached to an image forming apparatus includes a drum unit configured to rotatably hold a photosensitive drum, a developing unit that is assembled in such a manner as to be rotatable relative to the drum unit, and includes a developing roller configured to supply a developer to the photosensitive drum, gap maintaining members provided to the photosensitive drum or the developing roller on both end portions of the photosensitive drum in an axial direction, the gap maintaining members holding the developing roller while being apart from the photosensitive drum with a gap in between, and urging members configured to bias the developing unit toward the drum unit in such a direction that the developing roller comes into contact with the photosensitive drum. The urging members are respectively disposed on outer sides of the gap maintaining members disposed at both end portions in the axial direction. The drum unit or the developing unit includes an electric contact portion configured to come into contact with an electric contact of the image forming apparatus when the process cartridge is attached to the image forming apparatus, the electric contact portion being disposed between the gap maintaining members in the axial direction.
An image forming apparatus according to another aspect of the present invention includes a process cartridge that is attachable and detachable, and an electric contact connected to the process cartridge. The process cartridge includes a drum unit configured to rotatably hold a photosensitive drum, a developing unit that is assembled in such a manner as to be rotatable relative to the drum unit and includes a developing roller configured to supply a developer to the photosensitive drum, gap maintaining members provided to the photosensitive drum or the developing roller on both end portions of the photosensitive drum in an axial direction, the gap maintaining members holding the developing roller while being apart from the photosensitive drum with a gap in between, and urging members respectively disposed on outer sides of the gap maintaining members disposed at both end portions in the axial direction and configured to bias the developing unit toward the drum unit in such a direction that the developing roller comes into contact with the photosensitive drum. When the process cartridge is attached to the image forming apparatus, the electric contact comes into contact with and connected to an electric contact portion disposed between the gap maintaining members in the axial direction in the process cartridge.
Further features will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
An exemplary embodiment of the present invention is described below with reference to the drawings.
An axial direction of a rotatable photosensitive drum is defined as a longitudinal direction. A side on which the photosensitive drum receives driving force from an image forming apparatus main body in the longitudinal direction is defined as a drive side. An opposite side of the drive side is defined as a non-drive side.
The image forming apparatus illustrated in
In the apparatus main body A, a pickup roller 5a, a pair of feed rollers 5b, a pair of conveyance rollers 5c, a transfer guide 6, a transfer roller 7, a conveyance guide 8, a fixing device 9, a pair of discharge rollers 10, a discharge tray 11, and the like are arranged in this order in a conveyance direction. D of the sheet member P. The fixing device 9 includes a heating roller 9a and a pressing roller 9b.
An overall configuration of the cartridge B is described with reference to
The cartridge B includes a cleaning unit 60 and a developing unit 20. A general process cartridge is obtained by integrally forming a photosensitive drum (electrophotographic photosensitive member) and at least one of a charging unit, a development unit, and a cleaning unit serving as process units that perform processes on the photosensitive drum, to be a cartridge detachably attached to the apparatus main body. The process cartridge (cartridge B) according to the present exemplary embodiment includes the cleaning unit 60 as a drum unit including the photosensitive drum 62 and at least the developing unit 20 including the development unit.
As illustrated in
The cleaning member 77 includes a rubber blade 77a and a supporting member 77b. The rubber blade 77a is an elastic member that is made of rubber as an elastic material and has a blade shape. The supporting member 77b supports the rubber blade 77a. The rubber blade 77a extends in a counter direction relative to a rotational direction of the photosensitive drum 62 to be in contact with the photosensitive drum 62. In other words, the rubber blade 77a comes into contact with the photosensitive drum 62 with its distal end portion directed toward an upstream side in the rotational direction of the photosensitive drum 62.
As illustrated in
As illustrated in
The photosensitive drum 62 is drivingly rotated in a direction indicating by an arrow R in the figure, in accordance with an image forming operation, by receiving driving force from a main body driving motor (not illustrated) serving as a driving source.
The charging roller 66 is rotatably attached to both end portions of the cleaning frame 71 in the longitudinal direction (approximately parallel with the rotation axis direction of the photosensitive drum 62) via charging roller bearings 67. The charging roller 66 is in pressure contact with the photosensitive drum 62 with the charging roller bearings 67 being pressed by urging members 60 toward the photosensitive drum 62. The charging roller 66 is driven to be rotated by the rotation of the photosensitive drum 62.
As illustrated in
As illustrated in
The cleaning unit 60 includes the cleaning frame 71, the lid member 72, and the photosensitive drum 62, as well as a drum bearing 73 and a drum shaft 78 rotatably supporting the photosensitive drum 62. As illustrated in
On the other hand, the developing unit 20 includes, as illustrated in
As illustrated in
More specifically, at both end portions of the developing unit 20 in the longitudinal direction, a development first supporting hole 23a and a development second supporting hole 23b are formed in the developing container 23. At both end portions of the cleaning unit 60 in the longitudinal direction, first suspension holes 71i and second suspension holes 71j are formed in the cleaning frame 71. The cleaning unit 60 and the developing unit 20 are rotatably coupled to each other with the coupling pins 69 press-fit in the first suspension holes 71i and the development first supporting hole 23a, and in the second suspension holes 71j and the development second supporting hole 23b.
A drive side urging member 46R has a first hole portion 46Ra hooked on a boss 73c of the drum bearing 73 and a second hole portion 46Rb hooked on a boss 26a of the drive side development side member 26.
A non-drive side urging member 46F has a first hole portion 46Fa hooked on a boss 71k of the cleaning frame 71 and a second hole portion 46Fb hooked on a boss 37a of a bearing member 37.
In the present exemplary embodiment, the drive side urging member 46R and the non-drive side urging member 46F are each formed of a tension spring. The developing unit 20 is biased toward the cleaning unit 60 by the urging force of the springs, whereby the developing roller 32 is certainly pressed toward the photosensitive drum 62. With the gap maintaining members 38 attached to both end portions of the developing roller 32, the developing roller 32 is supported while being apart from the photosensitive drum 62 by predetermined gaps.
As illustrated in
An overview of an image forming process is described. The photosensitive drum 62 is drivingly rotated in the direction indicated by the arrow R at predetermined circumference speed. (process speed), based on a print start signal.
In the cartridge B, the charging roller 66 to which bias voltage is applied comes into contact with and uniformly charges the outer circumference surface of the photosensitive drum 62.
The exposure device 3 outputs a laser beam L, corresponding to image information, through a laser opening 71h formed in the cleaning frame 71 of the cartridge B. The outer circumference surface of the photosensitive drum 62 is scanned by the laser beam L, and thus an electrostatic latent image, corresponding to the image information, is formed on the outer circumference surface of the photosensitive drum 62.
In the developing unit 20 serving as a developing device, the toner T in the toner chamber 29 is stirred and conveyed as the first conveyance member 43, the second conveyance member 44, and the third conveyance member 50 rotate, to be sent to the toner supply chamber 28.
The toner T is carried on the surface of the developing roller 32 due to magnetic force of the magnet roller 34 (fixed magnet). The developing blade 42 frictionally charges the toner T and also regulates the thickness of the layer of the toner T on the circumference surface of the developing roller 32. With this layer of toner T, the electrostatic latent image is developed on the photosensitive drum 62 to be visualized as a toner image.
As illustrated in.
The sheet member P on which the toner image has been transferred is separated from the photosensitive drum 62 to be conveyed along the conveyance guide 8 to the fixing device 9. Then, the sheet member P passes through a nip portion between the heating roller 9a and the pressing roller 9b of the fixing device 9. The toner image is fixed on the sheet member P through press/heat fixing processing executed in the nip portion. The sheet member P as a result of the processing of fixing the toner image is conveyed to the pair of discharge rollers 10 to be discharged onto the discharge tray 11. This concludes the image forming process.
As illustrated in
In the process described above, the charging roller 66, the developing roller 32, the transfer roller 7, and the cleaning blade 77 serve as the process units that perform processes on the photosensitive drum 62.
How the cartridge B is attached to and detached from the apparatus main body A is described with reference to
The opening/closing door 13 is pivotally attached to the apparatus main body A. A cartridge insertion hole 17 is exposed when the opening/closing door 13 is open. The tray 18 with which the cartridge B is installed in the apparatus main body A is disposed in the cartridge insertion hole 17. The cartridge B can be attached to or detached from the tray 18 pulled out to a predetermined position. The cartridge B placed on the tray 18 is moved along a guiderail (not illustrated) in a direction indicated by an arrow C in the figure, to be installed in the apparatus main body A.
Thus, the photosensitive drum 62 coupled to a first coupling 70 (illustrated in
As illustrated in
The cartridge B has supported members including a supported member 73b and a supported member 73d of the drum bearing 73, as well as a drive side boss 71a, a non-drive side protrusion 71f, and a non-drive side boss 71g of the cleaning frame 71. The supported member 73b is supported by the drive side first supporting member 15a. The supported member 73d is supported by the drive side second supporting member 15b. The drive side boss 71a is supported by the rotationally supporting member 15c. The non-drive side protrusion 71f is supported by the non-drive side first supporting member 16a and the non-drive side second supporting member 16b. The non-drive side boss 71g is supported by the rotationally supporting member 16c. Thus, the cartridge B is positioned in the apparatus main body A.
Positions of the electric contact portion 47a and the urging members 46R and 46F are described with reference to
As described above, the developing roller 32 of the developing unit 20 is coupled in such a manner as to be rotatable about the coupling pins 69. The electric contact portion 47a provided on the developing unit 20 is in contact with the electric contact 12 of the apparatus main body A while receiving pressing force F2 therefrom when the cartridge B is attached to the apparatus main body A. The pressing force F2 is orientated in such a manner as to produce urging force of pushing the gap maintaining members 38 disposed on the end portions of the developing roller 32 in the longitudinal direction toward or away from the photosensitive drum 62. Thus, in conventional techniques, the pressing force applied to the gap maintaining members positioned at both axial direction end portions of the developing roller that comes in contact with the drum is largely unbalanced.
In view of this, the present exemplary embodiment features the urging members 46R and 46F that are disposed on both ends in the longitudinal direction, and biases the developing roller 32 of the developing unit 20 toward the photosensitive drum 62 about the coupling pins 69. More specifically, the urging members 46R and 46F are positioned on the outer sides of the gap maintaining members 38 in the longitudinal direction. Thus, a gap Z between the gap maintaining members 38 is provided in the longitudinal direction and the urging members 46B and 46F are disposed on both outer sides of the gap maintaining members 38.
In this configuration, when the contact portion between one of the gap maintaining members 38 on one side and the photosensitive drum 62 serves as a rotation center, the force of rotating the photosensitive drum 62 can be offset by the elastic force of the urging member 46R or 46F on the other side. For example, when the contact portion between one of the gap maintaining members 38 on the side of the urging member 46R and the photosensitive drum 62 serves as the rotation center, the urging member 46F on the other side is farther from the rotation center, and thus the moment acting to rotate the photosensitive drum 62 can be more effectively offset by the elastic force of the urging member 46F. As a result, counter force F1r and counter force F1f applied from the photosensitive drum 62 to the gap maintaining members 38 respectively on one and the other sides of the developing roller 32 in the longitudinal direction can be made small. Thus, the pressing force applied to the gap maintaining members 38 can be more balanced.
In the present exemplary embodiment, the electric contact portion 47a provided on the developing unit 20 is positioned between the gap maintaining members 38 in the longitudinal direction. More specifically, the electric contact portion 47a is disposed at a position within the gap Z between the gap maintaining members 38 in the longitudinal direction.
In this configuration, the pressing force F2 received by the electric contact portion 47a from the electric contact 12 of the apparatus main body A is distributed in a balanced manner to the counter force F1r and the counter force F1f so that not one of the counter force F1r and the counter force F1f but both are increased/decreased. Thus, the moment can be prevented from acting on the photosensitive drum 62 about the contact portion between one of the gap maintaining members 38 and the photosensitive drum 62, due to the pressing force F2 acting on the gap maintaining members 38. In this manner, the developing unit 20 can be biased toward the photosensitive unit 60, with the pressing force more balanced between the gap maintaining members 38 at both axial end portions of the developing roller 32 that comes into contact with the photosensitive drum 62.
As described above, in the present exemplary embodiment, the electric contact portion 47a is disposed between the gap maintaining members 38 in the longitudinal direction, and the moment about the contact portion involving one of the gap maintaining members 38 can be prevented from acting on the photosensitive drum 62. The urging members 46R and 46F are disposed on the outer sides of the gap maintaining members 38 on both ends in the longitudinal direction, that is, at positions sandwiching the gap maintaining members 38, and thus can more effectively offset the moment acting on the photosensitive drum 62.
The scope of the invention is not intended to be limited to the functions, the materials, the shapes, and the relative positions of the components described in the present exemplary embodiment, unless specifically noted otherwise.
A modification of the first exemplary embodiment is described with reference to some drawings. In this modification, a difference from the first exemplary embodiment is described in detail. The material, the shape, and the like are the same as those described in the first exemplary embodiment unless specifically noted otherwise. The common portions are denoted with the same reference numerals and will not be described in detail.
In the present modification, a configuration where a plurality of electric contact portions is arranged is described with reference to
As illustrated in
When there is a plurality of electric contacts as illustrated in
In the modification illustrated in
In this configuration, pressing force F2a and pressing force F2b respectively received by the electric contact portions 47a and 47b from the electric contact 12 of the apparatus main body A are distributed in a balanced manner so that not one of the counter force F1r and the counter force F1f but both are increased/decreased. Thus, the moment about the contact portion between the photosensitive drum 62 and one of the gap maintaining members 38 can be prevented from acting on the photosensitive drum 62, due to the pressing force F2a and the pressing force F2b acting on the gap maintaining members 38. In this manner, the developing unit 20 can be biased toward the photosensitive unit 60, with the pressing force more balanced between the gap maintaining members 38 on both axial end portions of the developing roller 32 that comes into contact with the photosensitive drum 62.
In the modification described above, the plurality of electric contact portions 47a and 47b is disposed between the gap maintaining members 38 in the longitudinal direction. Thus, the moment about the contact portion involving one of the gap maintaining members 38 can be prevented from acting on the photosensitive drum 62. The urging members 46R and 46F are disposed on the outer sides of the gap maintaining members 38 on both ends in the longitudinal direction, that is, at the positions sandwiching the gap maintaining members 38. Thus, the moment acting on the photosensitive drum 62 can be more effectively offset.
While the 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. 2015-203147, filed Oct. 14, 2015, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2015-203147 | Oct 2015 | JP | national |
