JP4126235B2 - Process unit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a process unit provided in an electrostatic image forming apparatus such as a printer, a copier, or a facsimile machine, and more specifically, a drum unit including a drum housing in which a photosensitive drum is provided, and a developing roller. The drum unit and the developing unit are related to a process unit that is rotatably connected to the developing unit.
[0002]
[Prior art]
One typical example of the above process unit is a drum unit (photosensitive unit) including a photosensitive drum and a developing unit including a developing roller that are rotatably (swingable) connected via a single support shaft. Configured to be. The drum unit includes an outer support side wall in which a support hole is formed, and the development unit includes an inner support side wall in which a support hole is formed. One pair and the other pair of support side walls are supported via a single support shaft that passes through each support hole. One end of the support shaft is supported through a bearing member that is detachable in a support hole in the outer support side wall of the drum unit. A tension coil spring is disposed between the drum unit and the developing unit, and is biased so as to be attracted to each other (see Patent Document 1).
[0003]
When the process unit is used as a process unit having a predetermined gap between the photosensitive drum and the developing roller, the gap between the photosensitive drum and the developing roller is maintained with high accuracy. , Both units are required to be assembled securely without play. If the support shaft portion between the photosensitive drum and the developing roller has a backlash and sufficient accuracy cannot be obtained, the gap cannot be ensured with high accuracy, and thus the required developing performance may not be ensured. Further, when assembling the photosensitive drum and the developing roller, it is also required that the assembling work is easy while satisfying the above requirements.
[0004]
In the process unit disclosed in the cited document 1, as described above, the photosensitive drum and the developing roller are configured to be connected via the support shaft and the bearing member. I can say that. Therefore, the accuracy and assembly accuracy of each part greatly affect the accuracy of the gap between the photosensitive drum and the developing roller. Therefore, in order to ensure the gap with high accuracy, each part is manufactured with high accuracy. In addition, it is required that each part can be easily assembled with high accuracy and without looseness. That is, in the process unit disclosed in the cited document 1, in order to ensure the gap between the photosensitive drum and the developing roller with high accuracy, it is necessary to considerably increase the manufacturing accuracy and the assembly accuracy for each component. Therefore, an increase in cost cannot be avoided, and there is still room for further improvement in assembly workability.
[0005]
[Patent Document 1]
JP-A-9-319288 [0006]
[Problems to be solved by the invention]
An object of the present invention is to provide a novel process unit that can secure a gap between a photosensitive drum and a developing roller with high accuracy, and that is easy to assemble at low cost.
[0007]
[Means for Solving the Problems]
According to the present invention, a drum unit including a drum housing in which a photosensitive drum is disposed, and a developing unit including a developing housing in which a developing roller is disposed, the drum unit and the developing unit can be rotated with respect to each other. In the connected process unit,
Support pin portions are provided on both sides in the longitudinal direction of the developing housing or the drum housing, respectively, and on both sides in the longitudinal direction of the drum housing or the developing housing, with respect to the axis of the photosensitive drum or the developing roller A projecting side wall projecting radially outward with respect to the shaft center and having a supported hole formed therein, respectively.
One or both of the overhanging side walls can be elastically deformed in the direction of separation and approaching with respect to each other or with respect to each other, and either or both of the overhanging side walls of the drum housing or the development housing can be elastically deformed. Alternatively, each of the supported holes of the developing housing is rotatably fitted to the corresponding developing housing or the supporting pin portion of the drum housing, and the developing unit and the drum unit are connected to each other so as to be rotatable.
A process unit is provided.
In a state where the developing unit and the drum unit are rotatably connected to each other, it is preferable that the reinforcing plate member is fixed to one or both side outer surfaces of the drum housing or the side wall including the projecting side wall of the developing housing.
One of the supported holes has a cylindrical portion, and a notch is formed in a partial region in the circumferential direction at one end portion on the inner side in the axial direction of the cylindrical portion and closer to the other supported hole, It is preferable that the circumferential length of the notch is defined to such an extent that the support pin portion to be fitted can be fitted .
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of a process unit configured according to the present invention will be described in more detail with reference to the accompanying drawings.
[0009]
Referring to FIGS. 1, 4, and 6, the process unit PU configured according to the present invention includes a drum unit 100 and a developing unit 200.
[0010]
The drum unit 100 includes a drum housing 102 formed from an appropriate elastically deformable synthetic resin, for example, modified PPE. A photosensitive drum 104 is rotatably supported on the drum housing 102 via a shaft 104a. The drum housing 102 is also provided with a main charger, a cleaning device, a static eliminator and the like (not shown). On both sides in the longitudinal direction of the drum housing 102, side walls including projecting side walls 106 and 108 that project outward in the radial direction with respect to the axial center of the photosensitive drum 104 are disposed. Supported holes 110 and 112 are formed at the distal end portions of the protruding side walls 106 and 108, respectively. The supported holes 110 and 112 are a common axis, and exist on an axis parallel to the axis 104 a of the photosensitive drum 104. One of the supported holes 110 has a substantially cylindrical shape, and one end portion on the inner side in the axial direction in the cylindrical portion, that is, a partial region in the circumferential direction at one end portion closer to the supported hole 112 is cut away. The circumferential length of this notch is defined to such an extent that a support pin portion 210 described later can be fitted. The other supported hole 112 is a through hole. The overhanging side walls 106 and 108 have a substantially cantilever shape, and one or both of the overhanging side walls 106 and 108, and in the embodiment, both ends can be elastically deformed in a direction away from or approaching each other. It is important to be.
[0011]
The developing unit 200 includes a developing housing 202 molded from an appropriate synthetic resin, for example, modified PPE. A developing roller 204 is rotatably supported on the developing housing 202. The developing roller 204 contains a stationary permanent magnet (not shown). Clearance setting rollers 205 are disposed at both ends of the developing roller 204 in the axial direction. The diameter of the gap setting roller is defined to be slightly larger than the diameter of the developing roller 204. A developing chamber (not shown) is provided in the developing housing 202, and a so-called two-component developer made of, for example, a magnetic carrier and a nonmagnetic toner is accommodated in the developing chamber. An endless circulation conveyance path (not shown) for circulating and conveying the toner is disposed in the developing chamber, and a stirring conveyance means (not shown) for agitating and conveying the developer is provided in the circulation conveyance path, for example, a plurality of the conveyance chambers. A rotating spiral blade member is disposed.
[0012]
Side walls 206 and 208 are formed on both sides in the longitudinal direction of the developing housing 202 so that the outer sides are exposed to the outside. On the side walls 206 and 208, support pin portions 210 and 212 extending outward are provided. The support pin portions 210 and 212 are on a common axis that is parallel to the axis of the developing roller 204. The distance between the tip ends of the support pin portions 210 and 212 is based on the distance between the opposite inner ends of the supported holes 110 and 112 formed at the tip portions of the protruding side walls 106 and 108 of the developing housing 202, respectively. Is also formed slightly larger.
[0013]
Referring to FIG. 1, in a state where the supported hole 112 of the extended side wall 108 of the drum housing 102 is fitted to the support pin portion 212 of the developing housing 202 from the outside in the axial direction, the extended side wall 106 of the drum housing 102 and 108, the supported hole 110 of the overhanging side wall 106 is fitted into the support pin portion 210 of the side wall 206 of the developing housing 202 from the outside in the axial direction while being elastically deformed so that the mutual interval is enlarged. The notch formed in the cylindrical portion of the supported hole 110 of the overhanging side wall 106 of the drum housing 102 contributes to facilitating the fitting operation. After the supported holes 112 and 110 of the overhanging side walls 108 and 106 of the drum housing 102 are fitted into the support pin portions 212 and 210 of the side walls 208 and 206 of the developing housing 202, respectively, the overhanging side wall 106 of the drum housing 102. When the elastic deformation operation with respect to and 108 is released, the projecting side walls 106 and 108 are returned to their original shapes by the elastic force. As a result, the supported holes 110 and 112 of the overhanging side walls 106 and 108 of the drum housing 102 are rotatably fitted to the support pin portions 210 and 212 of the side walls 206 and 208 of the developing housing 202, respectively. The developing unit 200 is connected around the support pin portions 210 and 212 so as to be rotatable relative to each other (see FIG. 2).
[0014]
In the embodiment, the drum unit 100 and the developing unit 200 are connected to each other around the support pin portions 210 and 212 so as to be pivotable with respect to one or both of the side walls including the protruding side walls 106 and 108 of the drum housing 102. A reinforcing plate member, in the embodiment, a metal reinforcing plate 4 is fixed to an outer surface on one side of the side wall including the overhanging side wall 106 (see FIGS. 3 and 5). The reinforcing plate 4 is detachably fastened to the side outer surface of the side wall including the overhanging side wall 106 by two screws 6. As a result, elastic deformation of the overhanging side wall 106 is prevented, so that the supported holes 110 and 112 of the overhanging side walls 106 and 108 are disengaged from the support pin portions 210 and 212 of the side walls 206 and 208 of the developing housing 202, respectively. Is reliably prevented.
[0015]
Referring to FIG. 1, a hook portion 114 is formed on the outer side surface of the projecting side wall 108 of the drum housing 102, and a hook portion 214 is formed on the outer side surface of the side wall 208 of the developing housing 202. A hook portion (not shown) is also formed on the outer side surface of the overhanging side wall 106 of the drum housing 102, and a hook portion (not shown) is also formed on the outer side surface of the side wall 206 of the developing housing 202. After the drum unit 100 and the developing unit 200 are connected as described above and the reinforcing plate 4 is fixed to one side wall of the drum housing 102, the tension coil spring 2 is disposed between the hook portions 114 and 214. A tension coil spring (not shown) is also disposed between the hook parts (not shown). As a result, the drum unit 100 and the developing unit 200 are rotated so as to be attracted to each other around the support pin portions 210 and 212. Since each of the gap setting rollers 205 disposed at both ends of the developing roller 204 is pressed against the outer peripheral surfaces of both ends of the photosensitive drum 104, there is a predetermined gap between the developing roller 204 and the photosensitive drum 104. Secured securely.
[0016]
According to the process unit PU of the present invention, the overhanging side walls 106 and 108 of the drum housing 102 are elastically deformed, whereby the supported holes 110 and 112 of the overhanging side walls 106 and 108 are changed into the side walls 206 and 208 of the developing housing 202. The support pin portions 210 and 212 can be directly fitted without interposing other components. That is, according to the process unit PU according to the present invention, the number of fitting parts and fitting parts between the drum unit 100 and the developing unit 200 can be minimized, and the drum unit 100 and the developing unit 200 can be kept at a low cost. Can be firmly connected with high accuracy. As a result, a predetermined gap between the photosensitive drum 104 and the developing roller 204 can be ensured with high accuracy without largely depending on the dimensional accuracy of the fitting parts as in the conventional process unit. Also, the assembly work is very easy.
[0017]
In the embodiment of the process unit PU according to the present invention, on the both sides in the longitudinal direction of the drum housing 102, the overhangs projecting radially outward with respect to the axial center of the photosensitive drum 104 and supported holes 110 and 112 are formed, respectively. Side walls 106 and 108 are disposed, and support pin portions 210 and 212 extending outward are respectively disposed on the side walls 206 and 208 on both sides in the longitudinal direction of the developing housing 200. On the contrary, on both sides in the longitudinal direction of the developing housing 200, there are provided protruding side walls that protrude outward in the radial direction with respect to the axis of the developing roller 204 and are respectively formed with supported holes. Another embodiment is also possible in which support pin portions are provided on the side walls on both sides in the longitudinal direction of the 100 so as to extend outwardly from the sides.
[0018]
【The invention's effect】
According to the process unit PU of the present invention, the gap between the photosensitive drum 104 and the developing roller 204 can be secured with high accuracy, and the assembly is easy at low cost.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of a preferred embodiment of a process unit configured in accordance with the present invention.
2 is a side view showing an assembled state of the process unit shown in FIG. 1, and is a side view as viewed from the left in FIG.
3 is a side view showing a state in which a metal reinforcing plate is attached to the outer side surface of the drum housing in the process unit shown in FIG. 2;
4 is a side view of only the drum unit in the process unit shown in FIG. 2;
5 is a side view showing a state in which a metal reinforcing plate is attached to the outer side surface of the side wall including the protruding side wall of the drum unit shown in FIG. 4;
6 is a side view of only the developing unit in the process unit shown in FIG. 2. FIG.
[Explanation of symbols]
2 Tensile coil spring 4 Reinforcement plate member 6 Screw 100 Drum unit 102 Drum housing 104 Photosensitive drum 104a Photosensitive drum axis 106, 108 Overhang side wall 110, 112 Supported hole 200 Developing unit 202 Developing housing 204 Developing roller 204a Developing roller Axis 206, 208 side wall 210 and 212 support pin part PU process unit

Claims (3)

In a process unit including a drum unit including a drum housing in which a photosensitive drum is disposed and a developing unit including a developing housing in which a developing roller is disposed, and the drum unit and the developing unit are rotatably connected to each other. ,
Support pin portions are provided on both sides in the longitudinal direction of the developing housing or the drum housing, respectively, and on both sides in the longitudinal direction of the drum housing or the developing housing, with respect to the axis of the photosensitive drum or the developing roller A projecting side wall projecting radially outward with respect to the shaft center and having a supported hole formed therein, respectively.
One or both of the overhanging side walls can be elastically deformed in the direction of separation and approaching with respect to each other or with respect to each other, and either or both of the overhanging side walls of the drum housing or the development housing can be elastically deformed. Alternatively, each of the supported holes of the developing housing is rotatably fitted to the corresponding developing housing or the supporting pin portion of the drum housing, and the developing unit and the drum unit are connected to each other so as to be rotatable.
A process unit characterized by that. The reinforcing plate member is fixed to one or both outer side surfaces of the drum housing or the side wall including the projecting side wall of the development housing in a state where the development unit and the drum unit are rotatably connected to each other. Process units. One of the supported holes has a cylindrical portion, and a notch is formed in a partial region in the circumferential direction at one end portion on the inner side in the axial direction of the cylindrical portion and closer to the other supported hole, The process unit according to claim 1, wherein a circumferential length of the notch is defined to such an extent that a support pin portion to be fitted can be fitted .

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