Patent Application
20190317445
The present disclosure relates to process units of electrophotographic image forming apparatuses and, in particular, to a process unit including a photosensitive drum, a charger, and a cleaner and an image forming apparatus including such a process unit.
An electrophotographic image forming apparatus has many functional components disposed around a photosensitive drum and forms an image through the action of each functional component. Examples of the functional components include a charger, an exposer, a developer, a transferer, a cleaner, a static eliminator, and the like.
In consideration of ease of maintenance and the like, an image forming apparatus is configured such that the photosensitive drum and each functional component are unitized alone or in combination so as to be easily attachable to and detachable from an image forming apparatus body.
Japanese Unexamined Patent Application Publication No. 2011-253119 discloses an image forming apparatus including a photosensitive unit and a charging unit. The image forming apparatus disclosed in Japanese Unexamined Patent Application Publication No. 2011-253119 is configured such that the charging unit is supported by a pressing lever and a rotational movement of the pressing lever allows the charging unit to displaced in a direction normal to a surface of a photosensitive drum of the photosensitive unit, so that maintenance of the charging unit can be carried out.
However, the technology disclosed in Japanese Unexamined Patent Application Publication No. 2011-253119 makes it necessary to separately provide a pressing lever that supports and displaces the charging unit, thus making the image forming apparatus complex in structure.
Further, there has been known a process unit in which a photosensitive drum, a charger, and a cleaner have been attached to a process frame. This process unit makes it necessary to remove the charger from the process frame in carrying out maintenance of the charger, as the charger is attached to the process frame. Further, this process unit also makes it necessary to remove the charger from the process frame first in carrying out maintenance of the photosensitive drum and the cleaner. Therefore, maintenance of the process unit has required many steps.
It is desirable to provide a process unit including a photosensitive drum, a charger, and a cleaner that makes it possible to easily carry out maintenance of the photosensitive drum, the charger, and the cleaner.
According to an aspect of the disclosure, there is provided a process unit including a photosensitive drum on which an electrostatic latent image is to be formed, a charger that charges an outer circumferential surface of the photosensitive drum to a predetermined polarity and a predetermined potential, a cleaner that removes residual toner from the outer circumferential surface of the photosensitive drum, a process frame that holds the photosensitive drum and is provided with the cleaner, and a charger cover that holds the charger and is rotatably supported on the process frame so as to move the charger away from or closer to the photosensitive drum.
According to an aspect of the disclosure, there is provided an image forming apparatus including a process unit configured as described above.
Embodiments of the present disclosure are described below with reference to the drawings.
The image forming apparatus 200 includes a photosensitive drum 10, a charger 20, a cleaner 30, an exposer 73, a developer 74, a transferer 75, a fixer 76, the scanner 81, a paper feed tray 82, and a paper output tray 83. The process unit 100 includes the photosensitive drum 10, the charger 20, and the cleaner 30.
The scanner 81 includes a document set tray, an automatic document feeder, a document reader, and the like. The document reader is provided with a document platen and a document scanner.
The paper feed tray 82 is a tray that accommodates recording paper such as plain paper, coated paper, color copy paper, and an OHP film. A plurality of the paper feed trays 82 are provided so that, for example, different sizes of paper are stored in each separate paper feed tray 82. Recording paper having an image formed thereon is ejected onto the paper output tray 83.
The photosensitive drum 10 is a roller-shaped member provided so as to be able to be driven to rotate in the direction of an arrow R1. The photosensitive drum 10 has a photosensitive film, formed on a surface thereof, on which an electrostatic latent image and a toner image are to be formed.
The charger 20 charges an outer circumferential surface of the photosensitive drum 10 to a predetermined polarity and a predetermined potential. In Embodiment 1, the charger 20 is a charging roller 21 and constitutes a charging unit 23. The charging roller 21 charges the photosensitive drum 10 by making contact with the outer circumferential surface of the photosensitive drum 10. The charging unit 23 is detachably attached to the charger cover 60.
The cleaner 30 removes residual toner from the outer circumferential surface of the photosensitive drum 10. The cleaner 30 includes a cleaning blade 31, a cleaning blade attacher 33, a waste toner receiver 35, and a toner-receiving sheet 37.
The cleaning blade 31 is a plate-shaped member that makes contact with the outer circumferential surface of the photosensitive drum 10 and scrapes the residual toner, paper powder, and the like away from the outer circumferential surface of the photosensitive drum 10. The cleaning blade attacher 33 is a member, formed as part of the process frame 50, to which the cleaning blade 31 is detachably fitted. The waste toner receiver 35, formed as part of the process frame 50, accommodates residual toner scraped away by the cleaning blade 31. The toner-receiving sheet 37 seals a space between the waste toner receiver 35 and the photosensitive drum 10.
While the photosensitive drum 10 is in a charged state, the exposer 73 (see
The developer 74 supplies toner to the outer circumferential surface of the photosensitive drum 10 and renders the electrostatic latent image formed on the outer circumferential surface of the photosensitive drum 10 visible as a toner image.
The transferer 75 applies a transfer bias to the back side of recording paper P passing through a space between the photosensitive drum 10 and the transferer 75 and transfers, onto the recording paper P, the toner image rendered visible on the outer circumferential surface of the photosensitive drum 10.
The fixer 76 heats and presses the recording paper P as the recording paper P passes through a fixing nip, thereby fusing and fixing the toner image transferred onto the recording paper P.
The process frame 50 is a frame that serves as a basis for the process unit 100. The process frame 50 rotatably holds the photosensitive drum 10 and is provided with the cleaner 30. The process frame 50 includes a cleaning blade attacher 33 and a waste toner receiver 35 that constitute the cleaner 30.
The charger cover 60 is a frame that is rotatably supported by the process frame 50. The charger cover 60 includes a charging unit holder 61, a rotator 63, a first position retainer 65, and a second position retainer 66.
The charging unit holder 61 is a member to which the charging unit 23 is detachably attached.
The rotator 63 is a member by which the charger cover 60 is rotatably supported on the process frame 50. The rotator 63 is provided in a location farther away from the photosensitive drum 10 than the charging roller 21 in a state where the charging roller 21 has been brought into contact with the photosensitive drum 10. For this reason, rotating the charger cover 60 on the rotator 63 makes it possible to move the charging roller 21 away from or closer to the photosensitive drum 10.
The first position retainer 65 and the second position retainer 66 are members that make contact with the horizontal plane HP in a case where a change in position has been made by rotating the charger cover 60 around the rotator 63.
The following describes changes in position of the charger cover 60 and the process frame 50 in the case of rotation of the charger cover 60 with respect to the process frame 50.
As shown in
Further, in a state where the charger cover 60 has been placed in the first position P1, the process frame 50 assumes a fourth position P4. In a state where the process frame 50 has been placed in the fourth position P4 on the horizontal plane HP, the horizontal plane HP and the cleaning blade attacher 33 form a first angle D1.
Placing the charger cover 60 in the second position P2 by rotating it with respect to the process frame 50 makes it possible to move the charger 20 away from the photosensitive drum 10 and turn the charger 20 upward and therefore makes it possible to easily carry out maintenance of the charger 20, the photosensitive drum 10 and the cleaner 30. This makes it possible, for example, to replace the charger 20 (charging unit 23) with a new one or remove the photosensitive drum 10 without removing the charger 20 (charging unit 23). Further, starting powder can be applied to the photosensitive drum 10 with the photosensitive drum 10 kept held by the process frame 50. The starting powder is applied in order to improve slip between the photosensitive drum 10 and the cleaning blade 31. Since the charger 20 can be moved away from the photosensitive drum 10, defects in charging due to the adhesion of the starting powder to the charger 20 can be reduced.
Further, the second position P2 is stabilized by the first position retainer 65 being in contact with the horizontal plane HP. This makes it possible to keep the charger 20 away from the photosensitive drum 10 and therefore makes it possible to easily carry out maintenance of the charger 20, the photosensitive drum 10, and the cleaner 30.
In a state where the charger cover 60 is in the second position P2, the process frame 50 maintains the fourth position P4. For this reason, in a state where the charger cover 60 is in the second position P2, the height of the center of the rotator 63 above the horizontal plane HP is H1.
Further, in a state where the charger cover 60 has been placed in the third position P3, the process frame 50 assumes a fifth position P5. Assuming that the horizontal plane HP and the cleaning blade attacher 33 form a second angle D2 in a state where the process frame 50 has been placed in the fifth position P5 on the horizontal plane HP, the second angle D2 is smaller than the first angle D1. This is because a change in position of the process frame 50 from the fourth position P4 to the fifth position P5 as entailed by a change in position of the charger cover 60 from the first position P1 or the second position P2 to the third position P3 causes the height of the center of the rotator 63 above the horizontal plane HP to increase from H1 to H2. In other words, the shapes of the process frame 50 and the charger cover 60 (e.g. the shape of the second position retainer 66) are set so that the height of the center of the rotator 63 above the horizontal plane HP increases from H1 to H2 and the angle formed by the horizontal plane HP and the cleaning blade attacher 33 decreases from the first angle D1 to the second angle D2.
As shown in
For comparison,
A process unit 100A according to Embodiment 2 of the present disclosure is configured such that in a state where the process frame 50 has been placed in the fifth position P5 on the horizontal plane HP, the second angle D2 formed by the horizontal plane HP and the cleaning blade attacher 33 is 0 degree. In this case, the waste toner RT can be inhibited from dropping from the waste toner receiver 35 into the process frame 50 in replacing the cleaning blade 31 with a new one. This makes it possible to improve maintainability of the cleaner 30.
In Embodiment 2, the cleaner 30 is provided with the toner-receiving sheet 37, which seals the space between the waste toner receiver 35 and the photosensitive drum 10. Since the waste toner RT hardly drops from the toner-receiving sheet 37, the toner-receiving sheet 37 may be lowered in a state where the process frame 50 is in the fifth position P5.
A process unit 100B according to Embodiment 3 of the present disclosure is provided with a stopper 68 that allows the charger cover 60 to maintain its position.
As shown in
In this case, the charger 20 can be kept away from the photosensitive drum 10 with the charger cover 60 maintained in the second position P2. This makes it possible to easily carry out maintenance of the charger 20, the photosensitive drum 10, and the cleaner 30.
The embodiments disclosed herein are examples in all respects and do not serve as the basis for limited interpretation. Accordingly, the technical scope of the present disclosure is not interpreted solely by the embodiments described above but is defined on the basis of the recitations in the scope of the claims. Further, all alterations falling within the meaning and range of equivalents of the scope of the claims are encompassed.
For example, although each of the present embodiments is configured such that the charger 20 constitutes the charging unit 23, the charging roller 21 may alternatively be attached to the charger cover 60.
The present disclosure is applicable to process units of electrophotographic image forming apparatuses and, in particular, to a process unit including a photosensitive drum, a charger, and a cleaner and an image forming apparatus including such a process unit.
The present disclosure contains subject matter related to that disclosed in Japanese Priority Patent Application JP 2018-079289 filed in the Japan Patent Office on Apr. 17, 2018, the entire contents of which are hereby incorporated by reference.
It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2018-079289 | Apr 2018 | JP | national |
