JP2004361719A - Photoreceptor drum support structure, process cartridge and electrophotographic image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure capable of accurately supporting a photoreceptor drum. <P>SOLUTION: In the photoreceptor drum support structure, a photoreceptor drum 7 including a cylinder having an electrophotographic sensitive layer on the outer circumferential surface and a gear coupling (drum gear 71) which is located at one end of the cylinder and rotates integrally with the cylinder is supported by a support member (bearing member 18c) in such a way that the drum 7 can freely be rotated with respect to a frame (cleaning frame 11d). The support member (bearing member 18c) has a cylindrical support part (drum support part 180) which rotatably supports the outer circumferential part of a shank 71c or the inner circumferential surface 71b3 of a gear part 71b, and an extension 181 which extends from the support part (drum support part 180) toward the other end of the cylinder in the rotational axis direction with a gap left between itself and the gear part 71b and a gap left between itself and the shank 71c. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a photosensitive drum support structure, a process cartridge, and an electrophotographic image forming apparatus.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus using an electrophotographic image forming process, an electrophotographic photosensitive member and process means acting on the electrophotographic photosensitive member are integrally formed into a cartridge, and this cartridge is attached to and detached from an image forming apparatus main body. A process cartridge system that makes it possible is employed. According to this process cartridge system, the maintenance of the apparatus can be performed by the user himself without relying on a service person, so that the operability can be remarkably improved. Therefore, this process cartridge system is widely used in image forming apparatuses.
[0003]
In the process cartridge, a photosensitive drum is generally supported. The following configuration is known as a configuration for supporting the photosensitive drum. Specifically, the photosensitive drum has a first flange with a first coupling portion fitted and fixed to the end of the drum cylinder. The first flange has a convex portion as a driven force transmitting portion and a support portion for positioning the process cartridge frame with the frame at coaxial and axially overlapping positions. The support is supported by the bearing. Thereby, the axial length of the first flange can be reduced (for example, see Patent Document 1).
[0004]
[Patent Document 1]
JP 2003-57998 A (paragraphs 0031 to 0066, FIG. 3)
[0005]
[Problems to be solved by the invention]
The present invention is a further development of the above prior art.
[0006]
An object of the present invention is to accurately support a photosensitive drum.
[0007]
It is another object of the present invention to accurately support the photosensitive drum by a gear coupling that does not vary in accuracy due to sink during molding.
[0008]
Another object of the present invention is to prevent the photosensitive drum from bending due to repulsion caused by gear engagement.
[0009]
Another object of the present invention is to provide a photosensitive drum supporting structure capable of stably driving a photosensitive drum and a developing roller of a process cartridge or a transfer roller of an electrophotographic image forming apparatus, and a process cartridge. And an electrophotographic image forming apparatus.
[0010]
Another object of the present invention is to suppress deformation of a supporting portion that rotatably supports a photoconductor drum due to a load, thereby improving the rotation accuracy of the photoconductor drum.
[0011]
Another object of the present invention is to improve assemblability when assembling a photosensitive drum to a process cartridge.
[0012]
Another object of the present invention is to improve the accuracy of a drum gear that rotates the photosensitive drum in response to drive transmission from the image forming apparatus and transmits drive to the developing roller and the transfer roller.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, in the support structure according to the present invention,
A photosensitive drum having a cylinder having an electrophotographic photosensitive layer on the outer peripheral surface and a gear coupling on one end side of the cylinder and rotating integrally with the cylinder is rotatable with respect to the frame by a support member. A photosensitive drum supporting structure for supporting,
The gear coupling,
A gear portion provided at one end of the gear coupling in the rotation axis direction of the cylinder,
A shaft portion having an outer peripheral portion that is concentric with the gear portion and has a smaller diameter than an inner peripheral portion of the gear portion, and is provided so as to overlap the gear portion in the rotation axis direction of the cylinder;
A protrusion provided on the rotation shaft direction outer end face of the shaft portion, for receiving drive transmission by fitting with a drive unit provided on the image forming apparatus main body;
Has,
The support member,
A cylindrical supporting portion rotatably supporting the outer peripheral portion of the shaft portion or the inner peripheral portion of the gear portion,
An extension portion extending from the support portion toward the other end side in the rotation axis direction of the cylinder by providing a gap with the gear portion and the shaft portion,
It is characterized by having.
[0014]
In the process cartridge according to the present invention,
In a process cartridge detachable from the electrophotographic image forming apparatus main body,
A photosensitive drum having a cylinder having an electrophotographic photosensitive layer on the outer peripheral surface and a gear coupling on one end side of the cylinder and rotating integrally with the cylinder;
Process means acting on the photoconductor drum;
A frame that houses the photoconductor drum and the process unit,
The gear coupling,
A gear portion provided at one end of the gear coupling in the rotation axis direction of the cylinder,
A shaft portion having an outer peripheral portion that is concentric with the gear portion and has a smaller diameter than an inner peripheral portion of the gear portion, and is provided so as to overlap the gear portion in the rotation axis direction of the cylinder;
A protrusion provided on the rotation shaft direction outer end face of the shaft portion, for receiving drive transmission by fitting with a drive unit provided on the image forming apparatus main body;
Has,
A cylindrical support portion rotatably supporting an outer peripheral portion of the shaft portion or an inner peripheral portion of the gear portion; and the gear portion and the other end of the cylinder in the rotation axis direction of the cylinder. The photosensitive drum is supported by a support member having the shaft portion and an extending portion extending with a gap.
[0015]
According to the above configuration, the support portion of the support member, whose strength has been increased by providing the extending portion, enters the substantially annular gap provided between the gear portion and the shaft portion of the gear coupling. Thus, the outer peripheral portion of the shaft portion or the inner peripheral portion of the shaft portion is supported, so that the rotation accuracy of the photosensitive drum can be improved.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Preferred embodiments of the present invention will be illustratively described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to them unless otherwise specified. Absent.
[0017]
In the following description, the longitudinal direction of the process cartridge is a direction that intersects the direction in which the process cartridge is attached to and detached from the apparatus main body (a direction substantially orthogonal to the axis of the image carrier), and is And a direction intersecting (substantially perpendicular to) the transport direction of the recording medium. In addition, left and right are left or right when the recording medium is viewed from above according to the transport direction of the recording medium. Further, the upper surface of the process cartridge is a surface located above when the process cartridge is mounted on the apparatus main body, and the lower surface is a surface located below.
[0018]
First, a process cartridge and an electrophotographic image forming apparatus to which the process cartridge can be attached and detached will be specifically described with reference to FIGS. FIG. 2 is a schematic cross-sectional view showing an outline of an image forming apparatus equipped with the process cartridge according to the present embodiment. More specifically, an electrophotographic laser beam printer which is an embodiment of the image forming apparatus is used. FIG. 2 is an explanatory diagram of the entire configuration. FIG. 3 is a schematic sectional view showing an outline of the process cartridge according to the present embodiment.
[0019]
Here, as the order of the description, first, the overall configuration of the process cartridge and the electrophotographic image forming apparatus using the same will be described, and then the configuration of the process cartridge attachment / detachment for attaching / detaching the process cartridge to / from the electrophotographic image forming apparatus main body will be described. .
[0020]
(Overall description of image forming apparatus)
As shown in FIG. 2, this electrophotographic image forming apparatus (laser beam printer, hereinafter referred to as an "image forming apparatus") A is a drum-shaped electrophotographic image forming apparatus that transmits information light based on image information from an optical system 1 as optical means. Irradiation is performed on a photoconductor (image carrier, hereinafter referred to as “photoconductor drum”) 7 to form an electrostatic latent image on the photoconductor drum 7, and the electrostatic latent image is developed with a developer (hereinafter, referred to as “toner”). Develop to form a toner image.
[0021]
Then, in synchronization with the formation of the toner image, the recording medium (recording paper, OHP sheet, cloth, etc.) 2 is separated and fed one by one from the cassette 3a by the pickup roller 3b and the pressing member 3c pressed against the cassette 3a. The toner image formed on the photosensitive drum 7 of the process cartridge B along the transport guide 3f1 is transferred to the recording medium 2 by applying a voltage to a transfer roller 4 as a transfer unit, and the recording medium 2 is transferred to the transport guide 3f2. The sheet is conveyed to the fixing means 5 along the path. The fixing means 5 includes a driving roller 5a, a fixing rotator 5d including a heater 5b and a cylindrical sheet rotatably supported by a support 5c, and applies heat and pressure to the recording medium 2 passing therethrough. The applied voltage fixes the transferred toner image. The recording medium 2 is conveyed by a discharge roller 3d, and is discharged to a discharge section 6 through a reverse conveyance path. In the present embodiment, the conveying means 3 is constituted by the pickup roller 3b, the pressing member 3c, the discharge roller 3d, and the like.
[0022]
(Process cartridge)
On the other hand, the process cartridge B includes an electrophotographic photosensitive member and at least one process means. Here, as the process means, for example, a charging means for charging an electrophotographic photosensitive member, a developing means for developing an electrostatic latent image formed on the electrophotographic photosensitive member, and a cleaning for cleaning toner remaining on the electrophotographic photosensitive member There are means.
[0023]
As shown in FIG. 3, the process cartridge B of the present embodiment rotates a photosensitive drum 7, which is an electrophotographic photosensitive member having a photosensitive layer, and applies a voltage to a charging roller 8, which is a charging unit, to apply a voltage to the photosensitive drum. 7 is uniformly charged. The charged photosensitive drum 7 is exposed to information light (light image) based on the image information from the optical system 1 through the exposure opening 9b to form an electrostatic latent image on the surface of the photosensitive drum 7. Then, the electrostatic latent image is developed by the developing unit 10.
[0024]
The developing unit 10 sends out the toner in the toner storage unit 10a by a rotatable sending member 10b which is a toner sending unit. Then, the developing roller 10d, which is a developing rotator (developer carrying member) incorporating the fixed magnet 10c, is rotated, and a toner layer provided with a triboelectric charge by the developing blade 10e is formed on the surface of the developing roller 10d. Then, the toner image is transferred to the photosensitive drum 7 in accordance with the electrostatic latent image, thereby forming a toner image and visualizing the toner image.
[0025]
After the toner image is transferred to the recording medium 2 by applying a voltage having a polarity opposite to that of the toner image to the transfer roller 4, the toner remaining on the photosensitive drum 7 is scraped off by the cleaning blade 11a and scooped by the squeeze sheet 11b. The remaining toner on the photosensitive drum 7 is removed by the cleaning unit 11 that collects the toner in the removed toner storage unit 11c.
[0026]
The process cartridge B described in the present embodiment rotatably supports the photosensitive drum 7 and incorporates a cleaning unit 11d in which the cleaning unit 11 and the charging roller 8 are incorporated, a developing unit 10, and a toner storage unit 10a. And a toner developing frame 10f. The toner developing frame 10f is rotatably supported with respect to the cleaning frame 11d so that the developing roller 10d of the developing means 10 can face the photosensitive drum 7 in parallel with a predetermined space therebetween. Spacers 10m for maintaining an interval between the photosensitive drum 7 and the photosensitive drum 7 are arranged at both ends of the developing roller 10d. Further, as shown in FIG. 3, the developing means 10 has a toner chamber (toner accommodating portion) 10a and a developing chamber 10i in a toner developing frame 10f.
[0027]
(Photoconductor drum)
Next, details of the drive transmission unit of the photosensitive drum will be described. FIG. 4 is an assembly perspective view for explaining a step of incorporating the photosensitive drum into the cleaning frame. FIG. 1 is a cross-sectional view showing a supporting structure of a drum gear and a bearing member. FIG. 5 is a cross-sectional perspective view showing a configuration for supporting a drum gear and a bearing member. FIG. 6 is a perspective view showing the appearance near the shaft of the drum gear.
[0028]
As shown in FIG. 4, the photosensitive drum 7 is provided with a cylinder having an electrophotographic photosensitive layer, a coupling means 70 for transmitting drive to one end side in the rotation axis direction of the photosensitive drum, and a drive transmission to the developing roller 10 and the transfer roller 4. And a gear gear 71 integrally formed with the gear. A flange 85 having a bearing on the other end side and having an unillustrated grounding means for grounding the photosensitive drum 7 is connected thereto. The coupling means 70 side of the photosensitive drum 7 is rotatably supported by the bearing member 18c. Here, the bearing member 18c is connected to the cleaning frame 11d by fastening means such as screws. The other end of the photosensitive drum 7 is rotatably supported by being pressed into the cleaning frame 11d so that the positioning pin 18d is accommodated in the positioning 18b.
[0029]
(Drum gear)
The drum gear 71 is a resin molded product, and in this embodiment, a polyacetal resin is used. Also, as shown in FIGS. 1 and 5, the drum gear 71 includes a coupling portion 71a fitted into the cylinder inner peripheral portion 7a of the photosensitive drum 7, a gear portion 71b, a shaft portion 71c supported by the bearing member 18c, and image forming. It comprises coupling means 70 for receiving drive transmission from the apparatus body.
[0030]
The photoreceptor drum 7 and the drum gear 71 are fixed at a joint 71a and rotate integrally. A first helical gear portion 71b1 for transmitting the drive to the developing roller 10 is provided outside the photosensitive drum 7 in the longitudinal direction, and a second helical gear portion 71b2 for transmitting the drive to the transfer roller 4 is provided outside the longitudinal direction. is there. Accordingly, the first helical gear portion 71b1 that transmits the drive to the developing roller 10 is located at a position close to the spacer 10m that determines the distance between the axis of the developing roller 10 and the photosensitive drum 7. Therefore, the distance between the pitches of the first helical gear portion 71b1 and the developing roller gear 10n can be accurately maintained.
[0031]
The shaft portion 71c has a round bar shape, and is provided at a position overlapping the first helical gear portion 71b1 and the second helical gear portion 71b2 in the longitudinal direction of the photosensitive drum 7.
[0032]
The first helical gear portion 71b1 includes a first helical gear tooth surface 71b11 provided on the outer peripheral side and a first inner peripheral surface 71b12 concentric with the root circle of the first helical gear portion 71b1. Become. Similarly to the first helical gear portion 71b1, the second helical gear 71b2 has the second helical gear tooth surface 71b21 provided on the outer peripheral side and the root circle of the second helical gear portion 71b2. The second inner peripheral surface 71b22 is concentric.
[0033]
In the present embodiment, the first inner peripheral surface 71b12 and the second inner peripheral surface 71b22 have the same inner diameter, and form the same inner peripheral surface 71b3. Further, in the present embodiment, the difference between the root circle diameter and the inner diameter of the inner peripheral surface 71b3 is about 2.5 mm to 5 mm. Since the outer diameter of the shaft portion 71c is smaller than the inner diameter of the inner peripheral surface 71b3, a ring-shaped gap 71b4 is formed. Therefore, the root circle and the inner peripheral surface 71b3 of the first helical gear portion 71b1 and the second helical gear portion 71b2 have a uniform thickness over the entire circumference. Therefore, the gear tooth surface does not sink during molding due to local thickness deviation, and a highly accurate gear tooth surface can be formed.
[0034]
Further, as shown in FIG. 6, the shaft 71c may have a recess 71c1 recessed from the outer diameter of the shaft at a part of the outer shape, and the round bar-shaped part may be a part of the outer shape.
[0035]
A coupling means 70 is provided on the longitudinally outer end surface 71c2 of the shaft portion 71c. When the process cartridge B is mounted on the image forming apparatus main body A, the coupling means 70 is fitted with a drive transmitting member (not shown) provided on the image forming apparatus main body A to receive the drive transmission. The cross section of the coupling means 70 which intersects with the direction of the rotation axis is a non-circular cross section having a plurality of corners and is twisted. The cross section of the drive transmission member that intersects the direction of the rotation axis is a non-circular cross section having a plurality of corners and is twisted.
[0036]
The longitudinally outer end surface 71c2 of the shaft portion 71c is located at substantially the same longitudinal position as the longitudinally outer end surface of the second helical gear portion 71b2. Therefore, the root portion of the coupling means 70 is located at substantially the same position as the longitudinally outer end face of the second helical gear portion 71b2. As a result, it is possible to secure a wide tooth width of the gear, to optimize the strength and the meshing ratio, and to obtain a good image.
[0037]
Next, the bearing member 18c will be described in detail with reference to FIGS. 7 and 8 are perspective views showing the appearance of the drum bearing according to the present embodiment.
[0038]
The bearing member 18c includes a drum support portion 180 for rotatably supporting the photosensitive drum 7, an arc portion 18c1 used as a mounting guide when a process cartridge B described later is attached to and detached from the image forming apparatus main body A, and a rotation stopper. This is a resin part in which the portion 18c2 and the contact portion 18c3 are integrally formed. In this embodiment, a styrene resin is used.
[0039]
The drum support 180 has a cylindrical shape, an outer diameter smaller than the inner peripheral surface 71b3 of the drum gear 71, and an inner diameter fitted with the shaft 71c of the drum gear 71 (see FIG. 1). A cylindrical extending portion 181 is provided on the tip side of the drum supporting portion 180, that is, on the inner side in the longitudinal direction of the drum.
[0040]
The outer diameter of the extending portion 181 is smaller than the inner peripheral surface 71b3 of the drum gear 71, and the inner diameter is larger than the outer diameter of the shaft portion 71c of the drum gear 71. The drum supporting portion 180 rotatably supports the shaft portion 71c at a position overlapping the ring-shaped gap 71b4 of the drum gear 71 in the drum longitudinal direction. Accordingly, the drum supporting portion 180 and the second helical gear portion 71b2 have a positional relationship of overlapping in the longitudinal direction of the drum, and can receive a repulsive force due to gear engagement immediately below the gear. Thus, the photosensitive drum 7 can be driven to rotate without causing bending due to the repulsion.
[0041]
In addition, by providing the extending portion 181 on the distal end side of the drum supporting portion 180, the strength of the drum supporting portion 180 can be increased. Thereby, the deformation of the drum supporting portion 180 due to the external force applied to the photosensitive drum 7 can be suppressed, and the stable rotation drive can be performed.
[0042]
The extending portion 181 serves as a rough guide for allowing the drum support portion 180 to enter the gap 71b4 of the drum gear 71 when assembling the bearing member 18c to the cleaning frame 11d. Thereby, it is possible to improve the assemblability of the bearing member 18c.
[0043]
Next, the results of analyzing the difference in the amount of deformation of the drum support 180 with and without the extension 181 are shown below.
[0044]
In FIG. 8, (a) shows a drum bearing having an extension 181 and (b) shows a drum bearing without an extension. When the shape of the drum supporting portion 180 is a cylindrical shape having an inner diameter of 14 mm, an outer diameter of 17 mm, and a length of 4 mm in the drum longitudinal direction and a point load of 9.8 N is applied, the deformation amount is reduced to 70% by providing the extending portion 181. It turned out to be. In this case, the shape of the extending portion is 15 mm in inner diameter, 17 mm in outer diameter, and 6.5 mm in length in the drum longitudinal direction. In addition, the restraining surface was a surface 182.
[0045]
As shown in FIG. 9, the drum supporting portion 180 may be provided on the outer peripheral side of the cylindrical shape, and may rotatably support the inner peripheral surface 71 b 3 of the drum gear 71.
[0046]
When the user purchases and uses the process cartridge, the user holds the toner seal end 27a shown in FIG. 10 and pulls it out, whereby the toner passage opening 10k of the toner developing frame 10f is opened, and the toner is transferred from the toner chamber 10a to the developing chamber 10i. To be ready for insertion into the image forming apparatus main body A.
[0047]
Then, the process cartridge B is mounted on a predetermined position of the image forming apparatus main body A along a guide (not shown).
[0048]
(Removal of the process cartridge from the image forming apparatus)
The manner in which the process cartridge B is mounted on the apparatus main assembly A will be described with reference to FIGS.
[0049]
First, an opening / closing door member (not shown) constituting the discharge unit 6 of the image forming apparatus main body A is opened to expose a guide member (not shown), the arc portion 18c1 of the process cartridge is forward, and the rotation stopping portion 18c2 is The arc portions 18c1 and 18c2 of the process cartridge B are placed on the guide surface where the front of the guide member is slightly bent so as to be rearward. Therefore, the positioning portion 18b of the process cartridge B and the projection 11g are fitted to the first guide surface of the other guide member.
[0050]
In this state, the process cartridge B is pushed into the image forming apparatus main body A.
[0051]
As described above, the process cartridge B is mounted at the mounting position with respect to the apparatus main body. Next, when the door of the image forming apparatus A is closed, the triangular coupling of the cartridge B is fitted into the drive transmission member of the image forming apparatus main body A, which is not shown, and has a triangular shape. The rotational driving force is transmitted to B.
[0052]
Thereby, the process cartridge B rotates around the axis of the photosensitive drum 7 as the rotation center axis.
[0053]
The attitude described above becomes the attitude of the process cartridge B during image formation, and image formation is started.
[0054]
When the process cartridge B is removed from the image forming apparatus main body A, the process cartridge B is removed from the mounting position along the corresponding guide of the image forming apparatus main body A to the outside of the apparatus by an operation reverse to the above-described mounting operation. At the same time, the drum shutter 12 also rotates and closes so as to cover the photosensitive drum 7 sequentially.
[0055]
As described above, the case where the process cartridge described in the present embodiment forms a single-color image has been exemplified. Alternatively, the present invention can be suitably applied to a cartridge that forms a full color or the like.
[0056]
The electrophotographic photoreceptor is not limited to the photoreceptor drum, and includes, for example, the following. First, a photoconductor is used as a photoconductor. Examples of the photoconductor include amorphous silicon, amorphous selenium, zinc oxide, titanium oxide, and an organic photoconductor (OPC). As the shape on which the photoconductor is mounted, for example, a drum-shaped or belt-shaped one is used. For example, in the case of a drum-type photoconductor, a photoconductor is deposited or coated on a cylinder of aluminum alloy or the like. It was done.
[0057]
Also, as a developing method, various developing methods such as a known two-component magnetic brush developing method, a cascade developing method, a touch-down developing method, and a cloud developing method can be used.
[0058]
In addition, the configuration of the charging means also uses a so-called contact charging method in the above-described embodiment, but as another configuration, a metal shield such as aluminum is provided around three sides of a conventionally used tangs wire, and the tangs wire is provided. It goes without saying that a configuration may be used in which positive or negative ions generated by applying a high voltage are moved to the surface of the photoreceptor drum and the surface of the drum is uniformly charged.
[0059]
The charging unit may be a blade (charging blade), a pad type, a block type, a rod type, a wire type, or the like, in addition to the roller type.
[0060]
As a method for cleaning the toner remaining on the photosensitive drum, a cleaning unit may be configured using a blade, a fur brush, a magnetic brush, or the like.
[0061]
The above-described process cartridge includes, for example, an electrophotographic photosensitive member and at least one of processing means. Therefore, as an aspect of the process cartridge, in addition to the above-described embodiment, for example, an electrophotographic photosensitive member and a developing unit are integrally formed into a cartridge so as to be detachable from the apparatus main body. Further, there is an electrophotographic photosensitive member, a developing unit, and a charging unit or a cleaning unit, which are combined into a cartridge to be detachable from the apparatus main body.
[0062]
That is, the above-described process cartridge refers to a cartridge in which at least the developing unit and the electrophotographic photosensitive member are integrally formed as a cartridge and can be attached to and detached from the image forming apparatus main body. The process cartridge can be attached to and detached from the apparatus main body by the user himself. Therefore, the maintenance of the apparatus main body can be performed by the user himself.
[0063]
Further, in the above-described embodiment, a laser beam printer is exemplified as an electrophotographic image forming apparatus. However, the present invention is not limited to this. For example, an electrophotographic printer such as an electrophotographic copying machine and an LED printer, a facsimile Naturally, it can be used in an electrophotographic image forming apparatus such as an apparatus, a word processor, or a multifunction printer (multifunction printer or the like).
[0064]
The embodiments of the present invention also include the following embodiments.
[0065]
(Embodiment 1)
A photosensitive drum 7 having a cylinder having an electrophotographic photosensitive layer on the outer peripheral surface and a gear coupling (drum gear 71) at one end of the cylinder and rotating integrally with the cylinder is supported by a support member (bearing member 18c). ), The photosensitive drum support structure rotatably supporting the frame (cleaning frame 11d),
The gear coupling (drum gear 71)
A gear portion 71b provided at one end of the gear coupling in the rotation axis direction of the cylinder;
A shaft portion 71c having an outer peripheral portion concentric with the gear portion 71b and having a diameter smaller than an inner peripheral surface 71b3 of the gear portion 71b, and provided so as to overlap the gear portion 71b in the rotation axis direction of the cylinder;
A projection (coupling means 70) provided on the outer end face in the rotation axis direction of the shaft part 71c to be fitted with a drive means provided on the image forming apparatus main body A to receive drive transmission;
Has,
The support member (bearing member 18c)
A cylindrical supporting portion (drum supporting portion 180) rotatably supporting the outer peripheral portion of the shaft portion 71c or the inner peripheral surface 71b3 of the gear portion 71b;
An extending portion 181 extending from the support portion (drum support portion 180) to the other end in the rotation axis direction of the cylinder with a gap provided between the gear portion 71b and the shaft portion 71c;
A photosensitive drum support structure, comprising:
[0066]
(Embodiment 2)
The support member (bearing member 18c) is separate from the frame (cleaning frame 11d), and is fixed to the frame (cleaning frame 11d) by fastening means (screw). The photosensitive drum support structure according to the first embodiment.
[0067]
(Embodiment 3)
A photosensitive drum supporting structure according to claim 1 or 2, wherein a groove (gap 71b4) having a uniform cross section is formed between the shaft portion 71c and the gear portion 71b over the entire circumference. .
[0068]
(Embodiment 4)
The gear portion 71b has a tooth surface portion (a first helical gear portion 71b1 and a second helical gear portion 71b2) on an outer peripheral portion of the gear portion 71b. The photosensitive drum supporting structure according to any one of embodiments 1, 2 and 3, wherein the diameter difference between the inner peripheral surface 71b3 of the portion 71b and the inner diameter is approximately 2.5 mm to 5 mm.
[0069]
(Embodiment 5)
The support portion (drum support portion 180) supports a position where the tooth surface portion (the first helical gear portion 71b1, the second helical gear portion 71b2) of the gear portion 71b overlaps in the rotation axis direction of the cylinder. 5. The photosensitive drum supporting structure according to any one of embodiments 1 to 4, wherein
[0070]
(Embodiment 6)
The gear portion 71b includes:
A first helical gear portion located on the outer side in the rotation axis direction of the cylinder, and a second helical gear portion located on the inner side adjacent to the first helical gear portion,
The photosensitive device according to any one of embodiments 1 to 5, wherein the first helical gear portion transmits drive to the transfer roller 4 and the second helical gear portion transmits drive to the developing roller 10. Body drum support structure.
[0071]
(Embodiment 7)
In a process cartridge B detachable from the main body A of an electrophotographic image forming apparatus, a cylinder having an electrophotographic photosensitive layer on an outer peripheral surface, and a gear coupling (drum gear 71) on one end side of the cylinder and rotating integrally with the cylinder. A photosensitive drum 7 having
Process means (for example, charging roller 8, cleaning means 11) acting on the photosensitive drum 7,
A frame (cleaning frame 11d) for accommodating the photosensitive drum 7 and the process means;
The gear coupling (drum gear 71)
A gear portion 71b provided at one end of the gear coupling (drum gear 71) in the rotation axis direction of the cylinder;
A shaft portion 71c having an outer peripheral portion concentric with the gear portion 71b and having a diameter smaller than an inner peripheral surface 71b3 of the gear portion 71b, and provided so as to overlap the gear portion 71b in the rotation axis direction of the cylinder;
A projection (coupling means 70) provided on the outer end face in the rotation axis direction of the shaft part 71c to be fitted with a drive means provided on the image forming apparatus main body A to receive drive transmission;
Has,
A cylindrical support portion (drum support portion 180) for rotatably supporting the outer peripheral portion of the shaft portion 71c or the inner peripheral surface 71b3 of the gear portion 71b; The photoreceptor drum 7 is supported by a support member (bearing member 18c) having the gear portion 71b and the shaft portion 71c and an extending portion 181 extending with a gap toward the other end in the rotation axis direction. A process cartridge.
[0072]
(Embodiment 8)
The support member (bearing member 18c) is separate from the frame (cleaning frame 11d), and is fixed to the frame (cleaning frame 11d) by fastening means (screw). A process cartridge according to embodiment 7.
[0073]
(Embodiment 9)
9. The process cartridge according to claim 7, wherein a groove (gap 71b4) having a uniform cross section is formed between the shaft portion 71c and the gear portion 71b over the entire circumference.
[0074]
(Embodiment 10)
The gear portion 71b has a tooth surface portion (a first helical gear portion 71b1 and a second helical gear portion 71b2) on an outer peripheral portion of the gear portion 71b. The process cartridge according to any one of embodiments 7, 8 and 9, wherein the difference in diameter from the inner diameter of the inner peripheral surface 71b3 of the portion 71b is approximately 2.5 mm to 5 mm.
[0075]
(Embodiment 11)
The support portion (drum support portion 180) supports a position where the tooth surface portion (the first helical gear portion 71b1, the second helical gear portion 71b2) of the gear portion 71b overlaps in the rotation axis direction of the cylinder. The process cartridge according to any one of embodiments 7 to 10, wherein
[0076]
(Embodiment 12)
The gear portion 71b includes:
A first helical gear portion located on the outer side in the rotation axis direction of the cylinder, and a second helical gear portion located on the inner side adjacent to the first helical gear portion,
The process according to any one of embodiments 7 to 11, wherein the first helical gear portion transmits driving power to the transfer roller 4 and the second helical gear portion transmits driving power to the developing roller 10. cartridge.
[0077]
(Embodiment 13)
In the electrophotographic image forming apparatus A for detachably attaching the process cartridge B and forming an image on the recording medium 2,
A guide portion for mounting the process cartridge B according to any one of Embodiments 7 to 12,
Transfer means (transfer roller 4) for transferring the developer image formed in the process cartridge B onto the recording medium 2,
Conveying means 3 for conveying the recording medium 2,
An electrophotographic image forming apparatus comprising:
[0078]
【The invention's effect】
As described above, according to the present invention, the photosensitive drum can be supported with high accuracy.
[0079]
Further, the gear coupling, a gear portion, a shaft portion having an outer peripheral portion concentric with the gear portion and smaller in diameter than the inner peripheral surface of the gear portion, and provided so as to overlap the gear portion in the rotation axis direction of the cylinder; By forming the gear teeth, the tooth surface portion can be made uniform in thickness, and there is no occurrence of inaccuracy due to sink during molding of the gear coupling. As a result, it is possible to realize a photosensitive drum support structure, a process cartridge, and an image forming apparatus free from image defects such as banding caused by gear accuracy.
[0080]
In addition, the supporting member rotatably supports the outer peripheral portion of the shaft portion or the inner peripheral surface of the gear portion, so that repulsive force due to meshing of the gears can be received directly below the gear, and the photosensitive drum is driven by the repulsive force. Rotational drive can be received without bending.
[0081]
In the support member, the strength of the support portion is increased by providing an extension portion extending from the support portion to the other end side in the rotation axis direction of the cylinder with a gap provided between the gear portion and the shaft portion. Deformation of the support portion due to external force applied to the body drum can be suppressed.
[0082]
In addition, since the extending portion serves as a rough guide at the time of assembling, the assemblability of the support member can be improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a support structure of a drum gear and a bearing member according to an embodiment.
FIG. 2 is a schematic cross-sectional view illustrating an outline of an electrophotographic image forming apparatus according to an embodiment.
FIG. 3 is a schematic sectional view illustrating an outline of a process cartridge according to the embodiment.
FIG. 4 is an assembly perspective view for explaining a process of incorporating the photosensitive drum into the cleaning frame.
FIG. 5 is a sectional perspective view showing a configuration for supporting a drum gear and a bearing member according to the embodiment.
FIG. 6 is a perspective view showing an appearance near a shaft portion of the drum gear according to the embodiment.
FIG. 7 is a perspective view showing an appearance of a drum bearing according to the embodiment.
FIG. 8 is a perspective view comparing appearances for explaining a difference in strength between a drum bearing having an extending portion and a drum bearing having no extending portion.
FIG. 9 is a cross-sectional view showing a configuration for supporting a drum gear and a bearing member according to the embodiment.
FIG. 10 is an overall perspective view showing the appearance of the process cartridge according to the embodiment.
FIG. 11 is a left side view of the process cartridge according to the embodiment.
FIG. 12 is a right side view of the process cartridge according to the embodiment.
[Explanation of symbols]
1 Optical system
2 Recording media
3 transport means
4 Transfer roller
5 Fixing means
6 discharge section
7 Photoconductor drum
7a Inner circumference of cylinder
7a1 Triangular coupling
8 Charging roller
9b Exposure aperture
10f Toner developing frame
10 Developing means (developing roller)
11 Cleaning means
12 Drum shutter
18b Positioning unit
18c bearing member
18c1 arc
18c2 Rotation stop
18c3 contact part
18d positioning pin
27a Toner seal end
70 Coupling means
71 Drum gear
71a Joint
71b Gear section
71b1 First helical gear
71b11 First helical gear tooth surface
71b2 Second helical gear
71b21 Second helical gear tooth surface
71b3 Inner peripheral surface
71b4 gap
71c Shaft
71c1 recess
85 flange
180 drum support
181 Extension
A main body of image forming apparatus
B process cartridge

Claims (13)

A photosensitive drum having a cylinder having an electrophotographic photosensitive layer on the outer peripheral surface and a gear coupling on one end side of the cylinder and rotating integrally with the cylinder is rotatable with respect to the frame by a support member. A photosensitive drum supporting structure for supporting,
The gear coupling,
A gear portion provided at one end of the gear coupling in the rotation axis direction of the cylinder,
A shaft portion having an outer peripheral portion that is concentric with the gear portion and has a smaller diameter than an inner peripheral portion of the gear portion, and is provided so as to overlap the gear portion in the rotation axis direction of the cylinder;
A protrusion provided on the rotation shaft direction outer end face of the shaft portion, for receiving drive transmission by fitting with a drive unit provided on the image forming apparatus main body;
Has,
The support member,
A cylindrical supporting portion rotatably supporting the outer peripheral portion of the shaft portion or the inner peripheral portion of the gear portion,
An extension portion extending from the support portion toward the other end side in the rotation axis direction of the cylinder by providing a gap with the gear portion and the shaft portion,
A photosensitive drum support structure, comprising: The photosensitive drum supporting structure according to claim 1, wherein the support member is separate from the frame, and is fixed to the frame by a fastening unit. The photosensitive drum supporting structure according to claim 1, wherein a groove having a uniform cross section is formed between the shaft and the gear over the entire circumference. The gear portion has a tooth surface portion on an outer peripheral portion of the gear portion, and a difference in diameter between a root circle diameter of the tooth surface portion and an inner diameter of an inner peripheral portion of the gear portion is approximately 2.5 mm to 5 mm. The photosensitive drum supporting structure according to claim 1, 2 or 3, wherein: The photosensitive drum supporting structure according to claim 1, wherein the support portion supports a position overlapping a tooth surface of the gear portion in a rotation axis direction of the cylinder. The gear unit includes:
A first helical gear portion located on the outer side in the rotation axis direction of the cylinder, and a second helical gear portion located on the inner side adjacent to the first helical gear portion,
The photosensitive drum according to any one of claims 1 to 5, wherein the first helical gear portion transmits drive to a transfer roller, and the second helical gear portion transmits drive to a developing roller. Support structure. In a process cartridge detachable from the electrophotographic image forming apparatus main body,
A photosensitive drum having a cylinder having an electrophotographic photosensitive layer on the outer peripheral surface and a gear coupling on one end side of the cylinder and rotating integrally with the cylinder;
Process means acting on the photoconductor drum;
A frame that houses the photoconductor drum and the process unit,
The gear coupling,
A gear portion provided at one end of the gear coupling in the rotation axis direction of the cylinder,
A shaft portion having an outer peripheral portion that is concentric with the gear portion and has a smaller diameter than an inner peripheral portion of the gear portion, and is provided so as to overlap the gear portion in the rotation axis direction of the cylinder;
A protrusion provided on the rotation shaft direction outer end face of the shaft portion, for receiving drive transmission by fitting with a drive unit provided on the image forming apparatus main body;
Has,
A cylindrical support portion rotatably supporting an outer peripheral portion of the shaft portion or an inner peripheral portion of the gear portion; and the gear portion and the other end of the cylinder in the rotation axis direction of the cylinder. A process cartridge, wherein the photosensitive drum is supported by a support member having the shaft portion and an extending portion extending with a gap. The process cartridge according to claim 7, wherein the support member is separate from the frame, and is fixed to the frame by fastening means. 9. The process cartridge according to claim 7, wherein a groove having a uniform cross section is formed between the shaft and the gear over the entire circumference. 10. The gear portion has a tooth surface portion on an outer peripheral portion of the gear portion, and a difference in diameter between a root circle diameter of the tooth surface portion and an inner diameter of an inner peripheral portion of the gear portion is approximately 2.5 mm to 5 mm. The process cartridge according to claim 7, 8 or 9, wherein: The process cartridge according to any one of claims 7 to 10, wherein the support portion supports a position where the tooth surface portion of the gear portion overlaps in a rotation axis direction of the cylinder. The gear unit includes:
A first helical gear portion located on the outer side in the rotation axis direction of the cylinder, and a second helical gear portion located on the inner side adjacent to the first helical gear portion,
The process cartridge according to claim 7, wherein the first helical gear portion transmits drive to a transfer roller, and the second helical gear portion transmits drive to a developing roller. In an electrophotographic image forming apparatus for detachably attaching a process cartridge and forming an image on a recording medium,
A guide unit for mounting the process cartridge according to claim 7,
Transfer means for transferring the developer image formed in the process cartridge to the recording medium,
Conveying means for conveying the recording medium,
An electrophotographic image forming apparatus comprising:

Images