JP2004138777A - Photoreceptive drum, process cartridge and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photoreceptive drum whose frictional sound by rotation is comparatively small by enhancing the reliability of continuity with time between the inner peripheral surface of a drum part and the main body of an image forming apparatus, a process cartridge and the image forming apparatus. <P>SOLUTION: The photoreceptive drum 1 is provided with the drum part 2 and a bearing part 5 installed at the inside of the drum part 2 and engaged with a shaft member 10 inserted from the outside of the drum part 2. Then, the inner peripheral surface 2a of the drum part 2 is electrically connected with a conductive member 12 installed at the outside of the drum part 2 by interposing the bearing part 5 and the shaft member 10 by the engagement of the bearing part 5 with the shaft member 10. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a photosensitive drum used as an image carrier in an electrophotographic image forming process, and a process cartridge and an image forming apparatus having the same.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in an image forming apparatus using an electrophotographic method, such as a facsimile, a copying machine, a printer, or a multifunction machine thereof, a photosensitive drum is often used as an image carrier (for example, see Patent Document 1). .).
The photosensitive drum mainly includes a cylindrical drum portion, a flange portion that is press-fitted into openings at both ends of the drum portion, and the like.
[0003]
The drum portion of the photosensitive drum is obtained by forming a photosensitive layer made of an organic material on a base made of an aluminum material or the like. The photosensitive drum is installed in the image forming apparatus, and rotates in a predetermined direction around the center of the drum unit as a rotation center. Then, a desired image forming process is performed on the outer peripheral surface of the drum portion on which the photosensitive layer is formed.
[0004]
Here, in order to stably perform a desired image forming process on the photosensitive layer formed on the photosensitive drum, the substrate of the photosensitive drum is maintained at a predetermined potential (for example, ground). There is a need.
That is, it is necessary to electrically connect the inner peripheral surface of the drum portion of the photosensitive drum to a conductive member provided in the image forming apparatus main body, and to maintain a predetermined potential through the conductive member.
[0005]
FIG. 5 is a cross-sectional view showing a main part of a conventional photosensitive drum.
As shown in FIG. 1, the photosensitive drum 1 is mainly fastened to the drum portion 2, the flange portion 3 press-fitted to an end opening of the drum portion 2, and the inner peripheral surface 2 a of the drum portion 2 with screws 16. And a leaf spring 15 and the like.
Here, the flange portion 3 has a through hole at the center thereof, and the support shaft 11 fixed to the main body side plate 13 is engaged with the through hole. Thus, one end of the photosensitive drum 1 is supported by the support shaft 11.
[0006]
At this time, the leaf spring 15 installed on the inner peripheral surface 2 a of the drum unit 2 comes into contact with the tip of the support shaft 11. Thus, the inner peripheral surface 2 a of the drum portion 2 is electrically connected to the leaf spring 12 as a conductive member provided outside the photosensitive drum 1 via the leaf spring 15 and the support shaft 11.
Further, the flange portion 3 includes a gear 3a on an outer peripheral portion, and the gear 3a is engaged with a driving gear installed in the image forming apparatus main body. The photosensitive drum 1 is driven to rotate about the support shaft 11 by a drive gear.
[0007]
As described above, the conduction method according to the configuration of FIG. 5 is such that the leaf spring 15 fixed to the inner peripheral surface 2a is brought into point contact with the support shaft 11 inserted from the outside of the photosensitive drum 1 at the tip thereof. It is.
As a conduction method different from this, there is known a method in which a leaf spring contacting an inner peripheral surface 2a is brought into contact with an outer peripheral surface of a spindle inserted from the outside of the photosensitive drum 1 (for example, there is known) And Patent Document 1.).
[0008]
[Patent Document 1]
JP-A-11-272121 (page 2-3, FIG. 1-2)
[0009]
[Problems to be solved by the invention]
The above-described conventional image forming apparatus has a first problem that reliability of electrical conduction between the base of the photosensitive drum and the main body of the image forming apparatus with time is low. When the conduction between the photosensitive drum base and the image forming apparatus main body becomes unstable, the image quality of the toner image formed on the photosensitive drum is greatly affected.
[0010]
Specifically, in the case of the image forming apparatus of FIG. 5 described above, the leaf spring 15 and the tip of the support shaft 11 are in point contact with each other, so that conduction is not stable. Further, when the spring force of the leaf spring 15 decreases over time, the contact force between the two decreases, and the conductivity deteriorates.
[0011]
Also, in the case of the image forming apparatus according to the above-described Patent Document 1, the reliability of conduction over time is low because the leaf spring is in contact with the outer peripheral surface of the support shaft. That is, the rotation of the photosensitive drum wears the leaf spring that comes into contact with the support shaft, and the spring force decreases with time, so that the contact force between the two decreases and the conductivity deteriorates.
[0012]
Further, the above-described conventional image forming apparatus has a second problem that a loud friction noise is generated.
Specifically, in the case of the image forming apparatus shown in FIG. 5 described above, in order to ensure the contact between the leaf spring 15 and the tip of the spindle 11, the leaf spring 15 is attached to the tip of the spindle 11 with a relatively large spring force. Abut. Therefore, frictional noise generated at the contact portion between the support shaft and the leaf spring increases due to the rotation of the photosensitive drum. In particular, when the positions of these point contacts do not coincide with the center position of the support shaft 11, a larger fricative noise is generated.
[0013]
Also, in the case of the image forming apparatus according to Patent Document 1 described above, in order to ensure the contact between the leaf spring and the spindle, the leaf spring contacts the outer peripheral surface of the spindle with a relatively large spring force. ing. Therefore, frictional noise generated at the contact portion between the support shaft and the leaf spring increases due to the rotation of the photosensitive drum.
[0014]
SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-described problems, and has high reliability in conduction between the inner peripheral surface of the drum unit and the image forming apparatus main body over time, and has a relatively small friction noise due to rotation. An object of the present invention is to provide a drum, a process cartridge, and an image forming apparatus.
[0015]
[Means for Solving the Problems]
A photosensitive drum according to a first aspect of the present invention includes a drum unit and a bearing unit that is installed inside the drum unit and that engages with a shaft member inserted from outside the drum unit. An inner peripheral surface of the drum portion is electrically connected to a conductive member provided outside the drum portion through the bearing portion and the shaft member by engagement of the bearing portion and the shaft member. It is conductive.
[0016]
According to a second aspect of the present invention, in the photosensitive drum according to the first aspect, the bearing portion is inscribed in an inner peripheral surface of the drum portion.
[0017]
Further, a photosensitive drum according to a third aspect of the present invention is the photosensitive drum according to the first aspect of the present invention, further comprising an elastic member between the bearing portion and an inner peripheral surface of the drum portion.
[0018]
An image forming apparatus according to a fourth aspect of the present invention is the image forming apparatus according to any one of the first to third aspects, further comprising a flange portion at an end opening of the drum portion, wherein the flange portion comprises: It has a through hole penetrating the shaft member.
[0019]
A process cartridge according to a fifth aspect of the present invention includes the photosensitive drum according to any one of the first to fourth aspects, and the shaft member.
[0020]
According to a sixth aspect of the present invention, in the process cartridge according to the fifth aspect, the shaft member is formed integrally with a support shaft for determining a position of the photosensitive drum in the cartridge. .
[0021]
According to a seventh aspect of the present invention, in the process cartridge according to the fifth or sixth aspect, the shaft member is an elastic member.
[0022]
An eighth aspect of the present invention is the process cartridge according to any one of the fifth to seventh aspects, wherein a conductive grease is provided on an engagement portion where the bearing and the shaft member engage. Is applied.
[0023]
An image forming apparatus according to a ninth aspect of the present invention includes the photosensitive drum according to any one of the first to fourth aspects, the shaft member, and the conductive member. Things.
[0024]
According to a tenth aspect of the present invention, in the image forming apparatus according to the ninth aspect, the shaft member is formed integrally with a support shaft that determines a position of a photosensitive drum in the apparatus. is there.
[0025]
An image forming apparatus according to an eleventh aspect of the present invention is the image forming apparatus according to the ninth or tenth aspect, wherein the shaft member is an elastic member.
[0026]
An image forming apparatus according to a twelfth aspect of the present invention is the image forming apparatus according to any one of the ninth to eleventh aspects, wherein an electrically conductive portion is provided on the engagement portion with which the bearing portion and the shaft member engage. Grease is applied.
[0027]
In this specification, a “process cartridge” includes a charging unit that charges a photosensitive drum, a developing unit that develops an electrostatic latent image on the photosensitive drum, and a device that collects untransferred toner on the photosensitive drum. At least one of the cleaning units and the photosensitive drum are defined as an assembly integrally formed as a cartridge and detachably formed in the main body of the image forming apparatus.
[0028]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each of the drawings, the same or corresponding portions are denoted by the same reference characters, and description thereof will be appropriately simplified or omitted.
[0029]
Embodiment 1 FIG.
Embodiment 1 of the present invention will be described in detail with reference to FIGS.
FIG. 1 is a configuration diagram illustrating an entire facsimile as an image forming apparatus according to the first embodiment. FIG. 2 is a cross-sectional view showing a driving-side main part of the photosensitive drum installed in the facsimile of FIG.
[0030]
First, the configuration and operation of the entire facsimile will be described with reference to FIG.
In FIG. 1, reference numeral 1 denotes a photosensitive drum, 22 denotes an optical unit that irradiates a laser beam onto the photosensitive drum 1 based on image information, 23 denotes a charging unit that charges the photosensitive drum 1, and 24 denotes a photosensitive drum. A developing unit for developing the electrostatic latent image formed on the photosensitive drum 1; a transfer unit 25 for transferring the toner image formed on the photosensitive drum 1 to transfer paper; and a cleaning unit 26 for collecting untransferred toner on the photosensitive drum 1. , 29 is a paper feed unit for storing the transfer paper, 30 is a paper feed roller for supplying the transfer paper from the paper feed unit 29 toward the conveyance path, and 32 is a fixing device for fixing the toner image on the transfer paper after the transfer process. Reference numeral 33 denotes a paper discharge roller for discharging the transfer paper after the fixing process toward the paper discharge part, and reference numeral 34 denotes a paper discharge part on which the discharged transfer paper is stacked.
[0031]
The operation at the time of reception in the facsimile configured as described above will be briefly described.
The photosensitive drum 1 is rotationally driven clockwise in FIG. 1 by a driving unit (not shown). Then, first, the surface of the photoconductor drum 1 is charged at the position of the charging unit 23. Thereafter, the charged surface of the photosensitive drum 1 reaches a laser beam irradiation position.
[0032]
Then, a laser beam is emitted from the optical unit 22 toward the photosensitive drum 1 based on the image information on the transmission side transferred through the telephone line. As a result, an electrostatic latent image corresponding to the above-described image information is formed on the surface of the photosensitive drum 1.
Then, the surface of the photosensitive drum 1 on which the latent image has been formed reaches the position of the developing unit 24. Then, the developing unit 24 develops the latent image on the photosensitive drum 24.
[0033]
After that, the surface of the photosensitive drum 1 developed by the developing unit 24 reaches a position facing the transfer unit 25. Then, the transfer unit 25 transfers the toner image on the photosensitive drum 1 onto transfer paper. At this time, a small amount of untransferred toner not transferred to the transfer paper remains on the photosensitive drum 1.
[0034]
Thereafter, the surface of the photosensitive drum 1 having the untransferred toner that has passed through the position of the transfer unit 25 reaches a position facing the cleaning unit 26. In the cleaning unit 26, untransferred toner adhering to the drum surface is collected in the cleaning unit 26 by a cleaning blade in contact with the photosensitive drum 1.
Thereafter, the surface of the photosensitive drum 1 that has passed through the cleaning unit 26 reaches the position of the charge removing unit. Then, the potential on the surface of the photosensitive drum 1 is eliminated by the electricity eliminating section, and a series of image forming processes is completed.
[0035]
On the other hand, the transfer paper on which the toner image is transferred by the transfer unit 25 has been supplied from the paper supply unit 29. That is, one transfer sheet among the transfer sheets stored in the sheet feeding unit 29 is conveyed toward the conveyance path by the sheet feeding roller 30. Then, the transfer paper in the conveyance path reaches the position of the registration roller, and is conveyed to the transfer unit 25 by the registration roller in synchronization with the toner image on the surface of the photosensitive drum 1.
[0036]
Thereafter, the transfer paper after the transfer step reaches the position of the fixing unit 32. Then, the fixing section 32 fixes the toner image on the transfer paper after the transfer process.
Then, the transfer paper after the fixing step passes through the paper discharge rollers 33 and is discharged onto the paper discharge unit 34.
[0037]
The photosensitive drum 1 in FIG. 1 is configured to be detachable from the image forming apparatus.
On the other hand, the photosensitive drum 1, the charging unit 23, the developing unit 24, and the cleaning unit 26 may be a process cartridge integrally configured. In this case, the process cartridge provided with the photosensitive drum 1 of FIG. 1 is configured to be detachable from the image forming apparatus.
[0038]
Next, referring to FIG. 2, a photoconductor drum installed in the above-described facsimile will be described.
2, reference numeral 1 denotes a photosensitive drum, 2 denotes a drum portion of the photosensitive drum 1, 2a denotes an inner peripheral surface of the drum portion 2, 3 denotes a flange portion provided at an end opening of the drum portion 2, and 5 denotes a drum portion. 2, a bearing part installed in the case 2, 9 a case forming a part of the apparatus main body, 10 a shaft member integrally formed with the support shaft 11, 11 a support shaft fixed to the case 9, 12 a 4 shows a leaf spring as a conductive member installed in the apparatus main body.
[0039]
Here, the drum portion 2 of the photosensitive drum 1 is formed by forming a photosensitive layer made of an organic material on a base made of an aluminum material or the like. That is, the inner peripheral surface 2a of the drum unit 2 is also the inner peripheral surface of the base. Then, the above-described image forming process is performed on the outer peripheral surface of the drum unit 2 on which the photosensitive layer is formed.
[0040]
A flange 3 having a gear 3a is press-fitted to one end opening of the drum 2. A through hole is provided at the center of the flange portion 3. A support shaft 11 fixed to the case 9 is engaged with the through hole, and one end of the photosensitive drum 1 is supported by the apparatus main body.
Although not shown, a flange portion is also press-fitted to an end opening on the opposite side of the drum portion 2. The opposite end of the photosensitive drum 1 is supported by the apparatus main body by an engaging member that engages with the flange.
Here, the flange portion 3 press-fitted into the drum portion 3 is made of a resin material having no conductivity.
[0041]
A bearing 5 is press-fitted into the drum 2 of the photosensitive drum 1 so as to be in contact with the inner peripheral surface 2a. At the center of the bearing portion 5, a through hole that engages with the shaft member 10 is provided. Here, the center of the bearing 5 is formed so as to substantially coincide with the center of the drum 2. When the photosensitive drum 1 is installed in the apparatus main body (the installation direction in the direction of the arrow in the figure), the shaft member 10 is formed so as to be in close contact with the bearing portion 5 and engaged therewith.
The bearing 5 is made of, for example, a conductive resin containing carbon and having a small friction coefficient.
[0042]
One end of the shaft member 10 is engaged with the bearing portion 5 through the through hole of the flange portion 3, and the other end is in contact with a leaf spring 12 installed in the apparatus main body. Here, the shaft member 10 is made of a conductive material such as stainless steel. As a result, the inner peripheral surface 2a of the photosensitive drum 1 is electrically connected to the leaf spring 12 with the bearing 5 and the shaft member 10 interposed.
Although not shown, the leaf spring 12 is electrically connected to a metal housing of the apparatus main body.
[0043]
In the photosensitive drum 1 configured as described above, the gear 3a of the flange portion 3 and a drive gear (not shown) provided on the apparatus main body are engaged. The drive gear causes the photosensitive drum 1 to rotate around the support shaft 11 as a center of rotation. At this time, the bearing portion 5 engaged with the shaft member 10 also rotates integrally with the photosensitive drum 1 around the center thereof while maintaining contact with the shaft member 10.
[0044]
As described above, in the first embodiment, the shaft member 10 inserted from the outside of the photosensitive drum 1 is provided with the bearing 5 provided inside the photosensitive drum 1 and the shaft member 10 extending over the bearing width. Abut. As described above, the configuration of the first embodiment uses the surface contact between the shaft and the bearing while avoiding the contact depending on the spring property of the leaf spring. As a result, the electrical connection between the inner peripheral surface 2a of the drum unit 2 and the apparatus main body is enhanced, and the conductivity over time is stabilized. Further, since no urging force acts on the contact portion between the shaft member 10 and the bearing portion 5, it is possible to provide a device having relatively low friction noise.
[0045]
In the first embodiment, the bearing unit 5 installed on the photosensitive drum 1 is formed of a sliding bearing having conductivity. On the other hand, the bearing part 5 may be configured by a rolling bearing in which the inner ring and the outer ring are electrically connected via balls or rollers.
[0046]
Embodiment 2 FIG.
Referring to FIG. 3, a second embodiment of the present invention will be described.
FIG. 3 is a cross-sectional view illustrating a main part of the photosensitive drum according to the second embodiment, and corresponds to FIG. 2 of the first embodiment. Here, the second embodiment is different from the first embodiment mainly in the configuration of the bearing portion.
[0047]
3, reference numeral 5 denotes a bearing portion provided inside the drum portion 1, 5a denotes a chamfered portion of the bearing portion 5, 8 denotes a leaf spring as an elastic member provided on a part of the outer periphery of the bearing portion 5, and 10 denotes A shaft member integrally formed on the distal end side of the support shaft 11, and 11 denotes a support shaft fixed to the main body side plate 13.
[0048]
As shown in FIG. 3, the bearing 5 is provided on the inner peripheral surface 2 a of the drum 2 via a leaf spring 8. The leaf spring 8 is made of conductive spring steel. As a result, the inner peripheral surface 2a of the photosensitive drum 1 is electrically connected to the plate spring 12 provided outside via the plate spring 8, the bearing 5, the shaft member 10, and the support shaft 11.
Note that the support shaft 11 is integrally formed of the same material as the shaft member 10. The support shaft 11 is engaged with the flange portion 3 of the photoconductor drum 1 and serves as a rotation shaft of the photoconductor drum 1.
[0049]
As described above, also in the second embodiment, the shaft member 10 inserted from the outside of the photosensitive drum 1 contacts the bearing portion 5 provided inside the photosensitive drum 1 over a relatively wide range. . As a result, similarly to the first embodiment, the electrical connection between the inner peripheral surface 2a of the drum portion 2 and the apparatus main body is enhanced, the conductivity over time is stabilized, and an apparatus with relatively little noise is provided. can do.
[0050]
Further, in the second embodiment, unlike the first embodiment, since the leaf spring 8 is provided on the outer periphery of the bearing portion 5, the position of the shaft Thus, the bearing portion 5 can follow and move the center position. Thus, even when the hole center of the bearing portion 5 does not coincide with the shaft center of the shaft member 10, the shaft member 10 easily engages with the through hole of the bearing portion 5 and the bearing portion 5 Will rotate smoothly.
Further, the bearing portion 5 is provided with a chamfered portion 5 a, and the tip of the shaft member 10 is also provided with a chamfered portion. Thereby, the shaft member 10 can be easily engaged with the through hole of the bearing portion 5.
[0051]
In the second embodiment, a leaf spring 8 as an elastic member is provided on the outer periphery of the bearing 5. However, the configuration of the present invention is not limited to this, and an elastic member such as a conductive spring or rubber may be provided on the outer peripheral portion of the bearing portion 5.
[0052]
Embodiment 3 FIG.
Referring to FIG. 4, a third embodiment of the present invention will be described.
FIG. 4 is a cross-sectional view illustrating a main part of the photosensitive drum according to the third embodiment, and corresponds to FIG. 2 of the first embodiment. Here, the third embodiment is different from the first embodiment mainly in the configuration of the shaft member.
[0053]
As shown in FIG. 4, a shaft member 10 is press-fitted at the tip of the support shaft 11. The shaft member 10 is formed of a conductive elastic member such as a spring material. The bearing 5 is in contact with the inner peripheral surface 2a of the drum 2 as in the first embodiment. As a result, the inner peripheral surface 2a of the photosensitive drum 1 is electrically connected to the leaf spring 12 provided outside via the bearing 5, the shaft member 10, and the support shaft 11.
Note that, unlike the above embodiments, the bearing portion 5 of the third embodiment is formed integrally with the flange portion 3.
[0054]
As described above, also in the third embodiment, the shaft member 10 inserted from the outside of the photosensitive drum 1 contacts the bearing portion 5 provided inside the photosensitive drum 1 in a relatively wide range. . As a result, similarly to the above-described embodiments, the electrical connection between the inner peripheral surface 2a of the drum portion 2 and the apparatus main body is enhanced, the conductivity over time is stabilized, and an apparatus with relatively little noise is provided. can do.
[0055]
Further, in the third embodiment, unlike the first embodiment, since the shaft member 10 is formed of an elastic member, the shaft member 10 is located at the hole center position of the bearing portion 5 installed on the photosensitive drum 1 side. On the other hand, the shaft member 10 displaces the center position and easily follows. Thereby, even when the center of the hole of the bearing portion 5 does not match the center of the shaft of the shaft member 10, the shaft member 10 easily engages with the through hole of the bearing portion 5, and the bearing portion 5 Will rotate smoothly.
[0056]
In each of the above-described embodiments, the configuration is such that, in the engagement portion between the bearing portion 5 and the shaft member 10, both members are in direct contact. On the other hand, a configuration in which conductive grease is applied to an engagement portion between the bearing portion 5 and the shaft member 10 may be adopted. Then, in this case, even when there is a slight gap between the engagement portion between the bearing portion 5 and the shaft member 10, the conductive grease enters the gap, and the conductivity between the two can be further ensured. Further, the friction between the bearing portion 5 and the shaft member 10 can be reduced, and the generation of friction noise can be further reduced.
[0057]
It should be noted that the present invention is not limited to the above-described embodiments, and it is apparent that the embodiments can be appropriately modified in addition to those suggested in the embodiments within the scope of the technical idea of the present invention. It is. Further, the number, position, shape, and the like of the constituent members are not limited to the above embodiments, and can be set to a number, position, shape, and the like suitable for carrying out the present invention.
[0058]
【The invention's effect】
Since the present invention is configured as described above, the reliability of conduction between the drum base and the image forming apparatus main body over time is high, and the photosensitive drum, the process cartridge, and the image forming drum that generate relatively little friction noise due to rotation. An apparatus can be provided.
[Brief description of the drawings]
FIG. 1 is a configuration diagram illustrating an entire image forming apparatus according to Embodiment 1 of the present invention;
FIG. 2 is a cross-sectional view illustrating a main part of a photosensitive drum installed in the image forming apparatus of FIG.
FIG. 3 is a cross-sectional view illustrating a main part of a photosensitive drum according to Embodiment 2 of the present invention.
FIG. 4 is a sectional view showing a main part of a photoconductor drum according to a third embodiment of the present invention.
FIG. 5 is a cross-sectional view illustrating a main part of a conventional photosensitive drum.
[Explanation of symbols]
1 photoconductor drum (image carrier), 2 drum section, 2a inner peripheral surface,
3 flange, 5 bearing, 5a chamfer,
8 leaf spring (elastic member), 9 case,
10 shaft member, 11 support shaft,
12 leaf spring (conductive member), 13 body side plate.

Claims (12)

Drum part,
A bearing portion is provided inside the drum portion and is engaged with a shaft member inserted from the outside of the drum portion,
Due to the engagement between the bearing portion and the shaft member, the inner peripheral surface of the drum portion is electrically connected to a conductive member provided outside the drum portion via the bearing portion and the shaft member. A photosensitive drum characterized by the above-mentioned. The photosensitive drum according to claim 1, wherein the bearing portion is in contact with an inner peripheral surface of the drum portion. The photosensitive drum according to claim 1, further comprising an elastic member provided between the bearing and an inner peripheral surface of the drum. A flange portion is provided at an end opening of the drum portion,
The photosensitive drum according to any one of claims 1 to 3, wherein the flange portion includes a through hole that penetrates the shaft member. A process cartridge comprising: the photosensitive drum according to claim 1; and the shaft member. The process cartridge according to claim 5, wherein the shaft member is formed integrally with a support shaft that determines a position of the photosensitive drum in the cartridge. The process cartridge according to claim 5, wherein the shaft member is an elastic member. The process cartridge according to any one of claims 5 to 7, wherein conductive grease is applied to an engagement portion where the bearing portion and the shaft member engage. An image forming apparatus comprising: the photosensitive drum according to claim 1; the shaft member; and the conductive member. The image forming apparatus according to claim 9, wherein the shaft member is formed integrally with a support shaft that determines a position of a photosensitive drum in the apparatus. The image forming apparatus according to claim 9, wherein the shaft member is an elastic member. The image forming apparatus according to claim 9, wherein conductive grease is applied to an engagement portion where the bearing portion and the shaft member engage.

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