JP6129383B2 - Developing unit, process cartridge, and electrophotographic image forming apparatus - Google Patents

Description

  The present invention relates to a developing unit and a process cartridge, or an electrophotographic image forming apparatus using them.

  Here, the electrophotographic image forming apparatus forms an image on a recording medium using an electrophotographic image forming system. Examples of the electrophotographic image forming apparatus include an electrophotographic copying machine, an electrophotographic printer (for example, a laser beam printer, an LED printer, etc.), a facsimile apparatus, a word processor, and the like.

  In addition, the process cartridge is a charging unit, a developing unit, a cleaning unit, or the like as a process unit and an electrophotographic photosensitive drum integrally formed as a cartridge, and this cartridge is attached to the main body of the electrophotographic image forming apparatus. Can be attached and detached. The apparatus main body is an image forming apparatus portion excluding the process cartridge.

  The developing unit is a typical one constituting the process cartridge, and develops the electrostatic latent image formed on the electrophotographic photosensitive drum with a developer.

  2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus using an electrophotographic image forming process, an electrophotographic photosensitive drum and process means acting on the electrophotographic photosensitive drum are integrally formed as a cartridge, and the cartridge is detachable from the main body of the electrophotographic image forming apparatus The method is adopted.

  As shown in FIG. 2, the image forming apparatus using the process cartridge described above includes an inline type color electrophotographic image forming apparatus 100 in which a plurality of process cartridges 7 (7a, 7b, 7c, 7d) are arranged in a line. . In the process cartridge, when the image forming operation is not performed, it is desirable that the photosensitive drum and the developing roller be separated from each other to prevent the elastic layer of the developing roller from being plastically deformed and causing unevenness on the image. . A process cartridge and an image forming apparatus provided with a mechanism for this purpose have been proposed (Patent Documents 1 and 2).

  Here, in the process cartridge, a drum unit having a photosensitive drum and a developing unit having a developing roller are rotatably coupled by a swing center. The photosensitive drum is provided with a cartridge coupling at the axial end of the photosensitive drum. When the process cartridge is mounted on the apparatus main body, the cartridge coupling engages with the main body coupling provided on the apparatus main body, and the driving force is transmitted to the photosensitive drum.

  Further, the development unit is provided with an Oldham coupling at the axial end of the development driving force input shaft. When the process cartridge is mounted on the apparatus main body, the Oldham coupling engages with the main body developing coupling provided on the apparatus main body, and the driving force is transmitted.

  In such a configuration in which the developing unit having the developing roller takes the contact position and the separation position with respect to the photosensitive drum, even when the rotation center on the drive output side and the rotation center on the drive input side are misaligned, the development driving force A configuration for stably transmitting the driving force to the input shaft is employed. Specifically, a process cartridge provided with an Oldham coupling and an image forming apparatus have been proposed (Patent Document 3).

  In addition, each part constituting the process cartridge may be integrally formed of at least two kinds of materials having different compositions. By integrally molding materials having different functions into one component, it is possible to reduce the number of components and reduce the cost (Patent Document 4).

Japanese Patent No. 2900530 JP 2001-337511 A JP-A-11-338211 JP 2003-241495 A

  An object of the present invention is to restrict the development driving force input shaft and the Oldham coupling in the axial direction of the development driving force input shaft with a cheaper configuration in a bearing formed of at least two types of resin materials having different compositions. The present invention also provides a developing unit, a process cartridge, and an electrophotographic image forming apparatus including the developing unit that can prevent the bearings from being separated.

A typical configuration of the developing unit according to the present invention for achieving the above object is as follows:
A frame comprising: a first molded body having a base portion; and a second molded body made of a resin material different from that of the first molded body and having a through hole and supported by the base portion. When,
A developing roller comprising a shaft member rotatably supported by the through hole, and supplying a developer to the electrophotographic photosensitive drum;
A developing unit used in an electrophotographic image forming apparatus comprising:
The shaft member has a surface extending in a direction intersecting with the axial direction of the shaft member, which is formed by making the shaft diameter on one end side thinner than the central portion in the axial direction of the shaft member,
The second molded body, the surface of the shaft member and the first contact portion contacting the front SL located on the side of the central portion of the axial direction with respect to the first mold body, said first molded body A first retaining portion contacting the first molded body; and a second retaining portion positioned on the one end side in the axial direction with respect to the first molded body and contacting the first molded body. .

  According to this invention, it can prevent that a 2nd molded object isolate | separates.

FIG. 3 is a cross-sectional view illustrating a through shaft restricting configuration of a developing rear bearing in Embodiment 1. 1 is a configuration diagram of an electrophotographic image forming apparatus according to an embodiment of the present invention. It is sectional drawing of the process cartridge in embodiment of this invention. 1 is an external perspective view of a process cartridge according to an embodiment of the present invention. 2 is a perspective view of a developing unit in Embodiment 1. FIG. FIG. 3 is a diagram illustrating a support configuration of a developing roller in Embodiment 1. FIG. 3 is an exploded explanatory view of a shaft joint member in Embodiment 1. FIG. 3 is an explanatory cross-sectional view of a shaft joint member in Embodiment 1. FIG. 3 is a perspective view of a shaft joint member in a developing unit state according to the first exemplary embodiment. 3 is a perspective view illustrating a first main body driving member and a second main body driving member of the image forming apparatus in Embodiment 1. FIG. 3 is a diagram illustrating a contact configuration of a developing rear bearing in Embodiment 1. FIG. FIG. 10 is a cross-sectional view illustrating a developing rear bearing configuration of a developing unit in Embodiment 2. It is a figure explaining the contact structure of the conventional image development back bearing. FIG. 3 is a cross-sectional view illustrating a development rear bearing configuration of the development unit according to the first exemplary embodiment.

[Example 1]
Embodiments of a process cartridge and an electrophotographic image forming apparatus according to the present invention will be described. FIG. 2 is an overall configuration diagram of the color electrophotographic image forming apparatus according to the present embodiment.

(Overall configuration of image forming apparatus)
First, the overall configuration of an electrophotographic image forming apparatus (hereinafter referred to as an image forming apparatus) 100 will be described. As shown in FIG. 2, four process cartridges 7 (7a, 7b, 7c, 7d) that are detachable (removable) are mounted inside the apparatus main body 100A by mounting members (not shown). In FIG. 2, the process cartridge 7 is provided in the apparatus main body 100A so as to be inclined with respect to the horizontal direction.

  Each process cartridge 7 is provided with an electrophotographic photosensitive drum (hereinafter referred to as a photosensitive drum) 1 (1a, 1b, 1c, 1d). Further, around the photosensitive drum 1, there are a charging roller 2 (2a, 2b, 2c, 2d), a developing roller 25 (25a, 25b, 25c, 25d), a cleaning member 6 (6a, 6b, 6c, 6d) and the like. Process means are arranged with a predetermined positional relationship.

  The charging roller 2 charges the surface of the photosensitive drum 1 uniformly. The developing roller 25 develops the latent image formed on the photosensitive drum 1 with a developer (hereinafter referred to as toner) to form a visible image. The cleaning member 6 removes the toner remaining on the photosensitive drum 1 after the toner image formed on the photosensitive drum 1 is transferred to the transfer belt 9.

  A scanner unit 3 is provided below the process cartridge 7 for selectively exposing the photosensitive drum 1 based on image information and forming a latent image on the photosensitive drum 1.

  A cassette 17 containing a recording medium M is attached to the lower part of the apparatus main body 100A. A recording medium conveying unit is provided so that the recording medium M passes through the secondary transfer roller 70 and the fixing unit 74 and is conveyed above the image forming apparatus 100. That is, a feeding roller 54 that separates and feeds the recording medium M in the cassette 17 one by one, a transport roller pair 76 that transports the fed recording medium M, and a latent image and a recording medium formed on the photosensitive drum 1. A registration roller pair 55 for synchronizing with M is provided.

  Further, an intermediate transfer unit serving as an intermediate transfer unit for transferring a toner image formed on each photosensitive drum 1 (1a, 1b, 1c, 1d) above the process cartridge 7 (7a, 7b, 7c, 7d). A unit 5 is provided. The intermediate transfer unit 5 includes a driving roller 56, a driven roller 57, a primary transfer roller 58 (58a, 58b, 58c, 58d) at a position facing the photosensitive drum 1 of each color, and a position facing the secondary transfer roller 70. The transfer belt 9 is stretched over the opposite roller 59.

  The transfer belt 9 circulates in a counterclockwise direction indicated by an arrow A so as to face and contact all the photosensitive drums 1. Then, by applying a voltage to the primary transfer roller 58 (58a, 58b, 58c, 58d), the toner image is primarily transferred from the photosensitive drum 1 onto the transfer belt 9. The toner image on the transfer belt 9 is secondarily transferred to the recording medium M by applying a voltage to the opposing roller 59 and the secondary transfer roller 70 disposed in the transfer belt 9.

  When forming an image, each photosensitive drum 1 is rotated, and the photosensitive drum 1 uniformly charged by the charging roller 2 is selectively exposed from the scanner unit 3. Thereby, an electrostatic latent image is formed on the photosensitive drum 1. The latent image is developed as a toner image by the developing roller 25. Thus, each color developer image is formed on each photoconductive drum 1. In synchronization with this image formation, the registration roller pair 55 conveys the recording medium M to the secondary transfer position where the opposing roller 59 and the secondary transfer roller 70 are in contact with each other with the transfer belt 9 interposed therebetween.

  Then, each color developer image on the transfer belt is secondarily transferred to the recording medium M by applying a transfer bias voltage to the secondary transfer roller 70. As a result, a color image is formed on the recording medium M. The recording medium M on which the color image is formed is heated and pressurized by the fixing unit 74 to fix the developer image. Thereafter, the recording medium M is discharged to the discharge unit 75 by the discharge roller 72. The fixing unit 74 is disposed at the upper part inside the apparatus main body.

  The toner remaining on the transfer belt 9 without being secondarily transferred to the recording medium M is carried to the intermediate transfer body cleaning unit 71 by the subsequent movement of the transfer belt 9, and is removed from the transfer belt 9 and removed in the toner chamber 71a. Is housed in.

(Process cartridge)
Next, the process cartridge 7 embodying the present invention will be described with reference to FIGS. 3, 4, and 5. FIG. 3 is a main cross section of the process cartridge 7 containing toner (developer). The cartridge 7a containing yellow toner, the cartridge 7b containing magenta toner, the cartridge 7c containing cyan toner, and the cartridge 7d containing black toner have the same configuration.

  The process cartridge 7 (7a, 7b, 7c, 7d) includes a cleaning unit (drum unit) 26 (26a, 26b, 26c, 26d) as a first frame and a developing unit 4 (4a, 4b) as a second frame. , 4c, 4d). The cleaning unit 26 includes a photosensitive drum 1 (1a, 1b, 1c, 1d), a charging roller 2 (2a, 2b, 2c, 2d), and a cleaning member 6 (6a, 6b, 6c, 6d). . The developing unit 4 includes a developing roller 25.

  The photosensitive drum 1 is rotatably attached to the cleaning frame 27 of the cleaning unit 26 via the drum front bearing 10 and the drum back bearing 11. A drum coupling 16 and a flange 85 are provided at the end of the photosensitive drum 1. As described above, the charging roller 2 and the cleaning member 6 are disposed on the circumference of the photosensitive drum 1. Further, the residual toner removed from the surface of the photosensitive drum 1 by the cleaning member 6 falls into the removed toner chamber 27a.

  Then, by transmitting the driving force of a main body driving motor (not shown: driving source on the apparatus main body side) as a driving source to the drum coupling 16 of the cleaning unit 26, the photosensitive drum 1 is rotated according to the image forming operation. Drive. The charging roller 2 is rotatably attached to the cleaning frame 27 via the charging roller bearing 28, and is pressed toward the photosensitive drum 1 by the charging roller pressing member 46, and is driven to rotate by the photosensitive drum 1. To do.

  The developing unit 4 includes a developing roller 25 that contacts the photosensitive drum 1 and rotates in the direction of arrow B, and a developing frame 31 that supports the developing roller 25. The developing roller 25 is rotatably supported by the developing frame 31 via a pre-development bearing 12 and a developing back bearing 13 that are respectively attached to both sides of the developing frame 31.

  Further, on the circumference of the developing roller 25, a toner supply roller 34 that contacts the developing roller 25 and rotates in the direction of arrow C and a developing blade 35 for regulating the toner layer on the developing roller 25 are respectively disposed. . The rotation directions of the developing roller 25 and the toner supply roller 34 are not limited to this. Further, the toner accommodating portion 31 a of the developing frame 31 is provided with a toner conveying member 36 for agitating the accommodated toner and conveying the toner to the toner supply roller 34.

  The developing unit 4 is rotatably attached to the cleaning unit 26. The front support pins 14 and the back support pins 15 that are press-fitted into the cleaning frame 27 are engaged with the suspension holes 12 a and 13 a of the pre-development bearing 12 and the development back bearing 13. As a result, the developing unit 4 is supported by the cleaning frame 27 so as to be rotatable about the support pins 14 and 15 as rotation axes.

  The cleaning frame 27 is provided with a drum front bearing 10 and a drum back bearing 11 that rotatably support the photosensitive drum 1. The drum back bearing 11 supports a drum coupling 16 coupled to the photosensitive drum 1. The drum front bearing 10 supports a flange 85. Here, the drum coupling 16 is a drum coupling member for transmitting the driving rotational force (first driving rotational force) from the main body driving motor on the apparatus main body 100 </ b> A side to the photosensitive drum 1.

  Further, the developing unit 4 shown in FIG. 5 has a cleaning unit 26 by a pressure spring 38 provided on the developing frame 31 and a tension spring 39 provided on the pre-development bearing 12 when the process cartridge 7 forms an image. It is configured to be energized. By these pressure spring 38 and tension spring 39, the holes 12 a and 13 a of the pre-development bearing 12 and the development rear bearing 13 become the center of rotation, and a pressure is applied for the development roller 25 to contact the photosensitive drum 1.

  In the contact development method in which development is performed with the photosensitive drum 1 and the developing roller 25 in contact with each other, it is preferable that the photosensitive drum 1 is a rigid body and the developing roller 25 is a roller having an elastic body. As this elastic body, a solid rubber single layer or a solid rubber layer coated with a resin coating in consideration of charge imparting property to toner is used.

  Next, a series of operations related to image formation of the process cartridge 7 will be described. Each of the process cartridges 7 (7a, 7b, 7c, 7d) is positioned in the positioning unit on the apparatus main body 100A side in a state where the process cartridge 7 (7a, 7b, 7c, 7d) is mounted on the predetermined mounting part in the apparatus main body 100A by the mounting member. Has been fixedly supported. The developing unit 4 is rotatably supported by the fixed cleaning unit 26 with the support pins 14 and 15 as the rotation shaft.

  Each process cartridge 7 is mounted in the apparatus main body 100A in a predetermined state, and a first main body drive transmission member 66 described later disposed in the apparatus main body 100A with respect to the drum coupling 16 of the cleaning unit 26. Are engaged. A later-described second main body drive transmission member 53 disposed in the apparatus main body 100A is engaged with a later-described development driving force input unit 20 of the developing unit 4.

  The developing unit 4 (4a, 4b, 4c, 4d) of each process cartridge 7 has a pressing member 8 (8a, 8b, 8c, 8c) on the apparatus main body 100A side at the pressed portion 31b (FIG. 3) during non-image formation. 8d) is pressed and held in a predetermined separated position. That is, the developing unit 4 is rotated around the support pins 14 and 15 against the spring force of the pressure spring 38 and the tension spring 39 in the direction in which the developing roller 25 is separated from the photosensitive drum 1 in a non-contact manner. .

  At the time of image formation, the pressing of the pressed portion 31b by the pressing member 8 is released, and the developing unit 4 is held at the contact position. That is, the developing unit 4 is rotated around the support pins 14 and 15 while the developing roller 25 is in contact with the photosensitive drum 1 with a predetermined pressing force by the spring force of the pressure spring 38 and the tension spring 39. Yes.

  When the image information is sent to the image forming apparatus 100, a main body drive motor (not shown) starts rotating, and the driving rotational force is transmitted to the photosensitive drum 1, the developing roller 25, the toner supply roller 34, and the toner conveying member 36. The A charging bias voltage is applied to the charging roller 2 from a main body power supply unit (not shown) to uniformly charge the surface of the photosensitive drum 1. Then, exposure is performed from the scanner unit 3 according to the image information, and a latent image is formed on the photosensitive drum 1.

  The toner in the toner storage portion 31 a is sent to the toner supply roller 34 by the rotation of the toner transport member 36. Then, the toner supply roller 34 rotates to supply toner to the outer periphery of the rotating developing roller 25. The supplied toner is frictionally charged on the outer periphery of the developing roller 25 by the developing blade 35.

  Then, a developing bias voltage is applied to the developing roller 25 from a main body power supply unit (not shown). Thereby, the electrostatic latent image formed on the photosensitive drum 1 is developed. The developing roller 25 is disposed to face the photosensitive drum 1. The developing roller 25 is configured to contact the photosensitive drum 1 and develop the electrostatic latent image formed on the photosensitive drum 1.

(Configuration of development drive force input shaft and development drive force input section in the process cartridge)
Next, the structure for supporting the development driving force input shaft and the construction of the development driving force input unit in the process cartridge 7 embodying the present invention will be described with reference to FIGS. FIG. 6 is a view showing one end side (back side) in the longitudinal direction of the support portion of the developing roller 25 having a developing driving force input shaft.

  Here, the developing driving force input shaft for transmitting the driving of the main body driving motor to the developing unit 4 is the developing roller shaft (rotatable shaft member) 25j of the developing roller 25. Hereinafter, the developing driving force input shaft is referred to as a developing roller shaft 25j. The development driving force input shaft is not limited to the configuration of the development roller shaft 25j.

  As shown in FIG. 6, the developing roller shaft 25 j of the developing roller 25 is rotatably fitted in the through hole 13 b of the developing rear bearing 13. The configuration of the through hole 13b of the developing back bearing 13 will be described in detail later. A regulating roller 47 for regulating the contact amount of the developing roller 25 to the photosensitive drum 1 is rotatably fitted to the developing roller shaft 25j between the rubber roller portion 25g of the developing roller 25 and the developing back bearing 13. Is provided.

Here, the support structure on the one end side in the longitudinal direction of the developing roller 25 has been described, but the bearing portion is also provided integrally with the bearing member on the other end side in the longitudinal direction (front side), and the other end of the developing roller shaft 25j is also provided. The side is rotatably fitted. In the present embodiment, the developing driving force input unit is allowed to shift the axis of the main body driving transmission member 53 and the developing roller shaft 25j, and the driving force of the main body driving transmission member 53 is transmitted to the developing roller shaft 25j. The configuration of the Oldham coupling 20 will be described with reference to FIGS. 7 and 8. In FIG. 7, the developing rear bearing 13 is not shown in order to explain the configuration of the Oldham coupling 20. As shown in FIG. 7, the Oldham coupling 20 includes a driven side joint 21, an intermediate joint 22, and a drive side joint 23. Then, as shown in FIG. 7, a D-cut portion 25c is provided on the end surface of the developing roller shaft 25j. A hole (not shown) on the driven joint 21 side is formed in the same shape, and the driven joint 21 is engaged with the D-cut portion 25c of the developing roller shaft 25j. As a result, the drive is transmitted from the driven side joint 21 to the developing roller shaft 25j.

  The shaft portion 23 b of the drive side joint 23 is rotatably held in the hole 19 a of the joint holding member 19. Further, the drive side joint 23 is formed with a projection 23c that engages with a main body developing coupling 53 (FIG. 10) which is a second main body drive transmission member described later on the apparatus main body 100A side.

  In FIG. 8, the configuration of the Oldham coupling 20 will be described in more detail with reference to cross-sectional views. 8A is a cross-sectional view cut perpendicular to the direction of arrow H in FIG. 7, and FIG. 8B is a cross-sectional view cut perpendicular to the direction of arrow I in FIG. In (a), the driven side joint 21 is integrally provided with a rib 21a. The middle joint 22 is provided with a groove 22a, and the rib 21a and the groove 22a are fitted so as to be movable in the direction of arrow H in FIG. In (b), the drive side joint 23 is integrally provided with a rib 23a. The intermediate joint 22 is provided with a groove 22b, and the rib 23a and the groove 22b are fitted so as to be movable in the direction of arrow I in FIG.

  FIG. 9 is a view showing the configuration of the coupling provided in the process cartridge 7. Projections 23c1 to 23c3 projecting in the axial direction are formed on the end face of the drive side joint 23 of the Oldham coupling 20 provided in the developing unit 4. Further, a centering boss 23c4 for aligning the axis (rotation center) with the main body development coupling 53 protrudes from the end face of the drive side joint 23 in the axial direction. A drum coupling 16 is provided on one end side (back side) of the photosensitive drum 1 in the axial direction.

  The guide portion 19 b of the joint holding member 19 is guided in a groove 48 b of the side cover 48 fixed to the developing unit 4 with a screw (not shown) so as to be movable in a direction intersecting the axial direction of the developing roller 25.

  FIG. 10 is a diagram showing a configuration of a coupling provided on the apparatus main body 100A side. In FIG. 10, holes 53 a to 53 c are provided in a main body developing coupling 53 which is a second main body drive transmission member for transmitting driving from the apparatus main body 100 </ b> A to the developing roller 25.

  The main body development coupling 53 is biased toward the process cartridge 7 by a main body development coupling pressing member 73 such as a compression spring. The main body development coupling 53 is movable in the axial direction of the development roller 25. When the process cartridge 7 is mounted on the apparatus main body 100A, the phases of the protrusions 23c1 to 23c3 of the drive side joint 23 of the Oldham coupling 20 provided in the developing unit 4 and the holes 53a to 53c of the main body developing coupling 53 are shifted. May come into contact. In this case, the main body development coupling 53 can be retracted.

  The centering boss 23c4 of the drive side joint 23 and the centering hole 53e of the main body development coupling 53 are engaged with each other, so that the rotation centers of the drive side joint 23 and the main body development coupling 53 coincide. Then, when the main body developing coupling 53 rotates, the protrusions 23c1 to 23c3 of the driving side joint 23 of the Oldham coupling 20 and the holes 53a to 53c of the main body developing coupling 53 are engaged, and the developing roller 25 is driven. Rotational force is transmitted.

  A drum drive coupling 66 which is a first main body drive transmission member for transmitting drive from the apparatus main body 100 </ b> A to the photosensitive drum 1 has the same configuration as the main body development coupling 53. The drum drive coupling 66 is provided with a hole 66a.

  The drum drive coupling 66 is biased toward the process cartridge 7 by a drum drive coupling pressing member 77 such as a compression spring. The drum drive coupling 66 is movable in the axial direction of the photosensitive drum 1. When the process cartridge 7 is mounted on the apparatus main body 100A, the protrusion of the drum coupling 16 may come into contact with the hole 66a of the drum drive coupling 66 with a phase shift. In this case, the drum drive coupling 66 can be retracted.

  Then, when the drum drive coupling 66 rotates, the protrusion of the drum coupling 16 and the hole 66a of the drum drive coupling 66 are engaged, and the driving rotational force is transmitted to the photosensitive drum 1.

  Here, the drive transmission to the drum drive coupling 66 which is the first main body drive transmission member and the main body development coupling 53 which is the second main body drive transmission member is a main body drive motor (not shown) provided in the apparatus main body 100A. ). There are a configuration in which one motor is used for each color process cartridge 7 and a configuration in which driving is transmitted to the process cartridges 7 of several colors by one motor.

(Configuration of the through hole of the developing rear bearing in the process cartridge)
Next, the structure of the through hole 13b of the developing rear bearing 13 in the process cartridge 7 embodying the present invention will be described.

  As shown in FIG. 6, the developing roller shaft 25 j of the developing roller 25 is rotatably fitted in the through hole portion 13 b of the developing back bearing 13. Although FIG. 6 shows the bearing on the long rear side of the process cartridge 7, as shown in FIG. 5, the developing roller shaft 25 j is similarly connected to the through hole portion (not shown) of the pre-development bearing 12 on the front side of the process cartridge 7. ) Is rotatably fitted. The developing roller 25 is held by the developing unit 4 by fixing the bearing to the process cartridge 7 with a screw or the like.

  FIG. 1 is a sectional view of the developing roller 25 in FIG. 6 in the axial direction. As shown in FIG. 1, the developing rear bearing 13 is constituted by two-color molding that is integrally molded with at least two kinds of resin materials having different compositions.

  Here, for example, the bearing base portion 13a that is the first molded body of the developing back bearing 13 is molded using an insulating polystyrene resin in consideration of strength, cost, and the like. In addition, the through-hole portion 13b, which is the second molded body, is molded using a conductive polyacetal resin containing carbon black that has excellent conductivity and excellent sliding properties with the developing roller shaft 25j and the contact portion on the apparatus main body 100A side. doing. That is, the bearing base portion 13a that is the first molded body and the through hole portion 13b that is the second molded body are molded using resin materials having different compositions. The resin material, the number of materials, and the molding method are not limited to this.

  FIG. 11 shows a case where conductive resin is molded in two colors. The through hole portion 13b and the main body contact receiving portion 13d are integrally formed of a conductive resin so that the through hole portion 13b of the developing back bearing 13 and the main body contact receiving portion 13d are electrically connected. The developing roller shaft 25j is fitted into the through hole 13b, and the main body contact receiving portion 13d and the developing roller shaft 25j are electrically connected.

  FIG. 13 shows a case where an electrode plate having a conventional configuration is used. By bringing the electrode plate 13e into contact with the developing roller shaft 25j, the main body contact receiving portion 13d of the developing back bearing 13 and the developing roller shaft 25j are brought into conduction. By forming the developing back bearing 13 using two-color molding as shown in FIG. 11, a developing roller is provided from a power supply unit (not shown) provided on the apparatus main body 100A side without using parts such as the electrode plate 13e. It is possible to apply the developing bias voltage V to the shaft 25j. Accordingly, it is possible to reduce the cost by reducing the number of parts such as the electrode plate 13e.

  Next, the longitudinal restriction of the developing roller shaft 25j and the driven joint 21 will be described with reference to FIG. Here, the shaft diameter of the developing roller shaft 25j has a shape portion that is one step thinner from the diameter L2 to the diameter L1. That is, the developing roller shaft 25j has a stepped butting portion 25k.

  The through-hole portion 13b is provided with a first contact portion C that comes into contact with the stepped abutting portion 25k of the developing roller shaft 25j when receiving a load F1 from the developing roller shaft 25j. Further, on the opposite side of the through hole 13b in the longitudinal direction, when the driven joint 21 receives the load F2 from the main body developing coupling 53 side, the end face 21b of the driven joint 21 (end face of the shaft coupling member 20) is long. A second abutting portion D that abuts in the direction is provided.

  Here, the load F1 is a force applied to the developing roller shaft 25 when, for example, a force for regulating the developing roller 25 is applied in the axial direction of the developing roller 25 or when the process cartridge 7 is dropped. The load F2 is a force applied from the driven joint 21 via the main body development coupling 53 when the process cartridge 7 is inserted into the apparatus main body 100A and the main body development coupling 53 and the Oldham coupling 20 are engaged, for example. It is.

  The through hole 13b, which is the second molded body, is separated from the developing back bearing 13 (the bearing base portion 13a, which is the first molded body) when the loads F1 and F2 are received. A plurality of retaining portions S1 (first retaining portions) and S2 (second retaining portions) for prevention are provided.

  The retaining portions S1 and S2 are provided so as to overlap the bearing base portion 13a in a direction in which the through-hole portion 13b intersects the axial direction of the developing roller 25 (direction intersecting the through-hole axis). Here, the retaining portions S1 and S2 overlap the bearing base portion 13a on the entire circumference in the radial direction of the developing roller shaft 25j, but the shape of the overlapping portion is not limited thereto.

  The retaining portions S1 and S2 are in contact with the developing back bearing 13, so that the through hole portion 13b can be prevented from being separated from the developing back bearing 13 even when the loads F1 and F2 are applied to the through hole portion 13b.

  Next, the regulation part 13c provided in the internal diameter part of the through-hole part 13b is demonstrated using FIG. As shown in FIG. 14, a restricting portion 13 c that restricts the developing roller shaft 25 j and the driven joint 21 of the Oldham coupling 20 in the axial direction of the developing roller 25 is formed in the inner diameter portion of the through hole portion 13 b.

  Here, the shaft diameter of the developing roller shaft 25j is a shape that is one step thinner from the diameter L2 to the diameter L1 in the through hole 13b. That is, the developing roller shaft 25j has a stepped butting portion 25k in the through hole 13b. When the load F1 is applied to the developing roller shaft 25j, the stepped butting portion 25k can come into contact with the surface of the first contact portion A of the restricting portion 13c. As a result, the developing roller shaft 25j is regulated in the direction toward the back of the shaft of the developing roller 25.

  Similarly, when the driven joint 21 receives the load F2 from the main body development coupling 53, the end surface 21b of the driven side joint 21 (the end surface of the shaft coupling member 20) is the second contact portion B of the restricting portion 13c. It abuts on the surface and is regulated.

  As shown in FIG. 14, by forming the restricting portion 13c in the inner diameter portion of the through hole portion 13b, the shaft diameter of the fitting portion between the developing roller shaft 25j and the through hole portion 13b can be supported by L2. . Therefore, compared to the configuration shown in FIG. 1, the developing roller 25 can be supported by the thick shaft diameter portion L2 of the developing roller shaft 25j.

[Example 2]
Another embodiment will be described with reference to FIG. Since the configuration of the image forming apparatus 100 and the configuration of the process cartridge 7 are the same as those in the first embodiment, description thereof is omitted.

  In FIG. 12, the structure from which the through-hole part 13b in FIG. 14 differs in the retaining shape is shown. Here, the retaining shape of the through-hole portion 13b is configured at one place inside the bearing base portion 13a.

  The restricting portion 13c at the inner diameter portion of the through hole portion 13b receives the load F1 and the load F2 in the axial direction of the developing roller 25, respectively. Since the load F1 and the load F2 are the same as those in the first embodiment, description thereof is omitted. Even when the retaining shape of the through-hole portion 13b is configured in one place inside the bearing base portion 13a, the through-hole portion 13b that receives the load F1 and the load F2 is separated from the bearing base portion 13a by the retaining portions S1 and S2. Is prevented.

  100..Electrophotographic image forming apparatus, 100A..Main body, 1..Electrophotographic photosensitive drum, 4..Developing unit, 25..Developing roller, 25j..Development driving force input shaft, 13 .. 13a ··· Bearing basic portion, 13b · · Through hole portion, 20 · · Shaft coupling member (Oldham coupling), 53 · · Body drive transmission member, 25k · · Stepped abutment portion, 21c · · Shaft coupling member 20 End face, C ... first contact part, D ... second contact part, S1, S2 ... retaining part

Claims (8)

A frame comprising: a first molded body having a base portion; and a second molded body made of a resin material different from that of the first molded body and having a through hole and supported by the base portion. When,
A developing roller comprising a shaft member rotatably supported by the through hole, and supplying a developer to the electrophotographic photosensitive drum;
A developing unit used in an electrophotographic image forming apparatus comprising:
The shaft member has a surface extending in a direction intersecting with the axial direction of the shaft member, which is formed by making the shaft diameter on one end side thinner than the central portion in the axial direction of the shaft member,
The second molded body, the surface of the shaft member and the first contact portion contacting the front SL located on the side of the central portion of the axial direction with respect to the first mold body, said first molded body A first retaining portion contacting the first molded body; and a second retaining portion positioned on the one end side in the axial direction with respect to the first molded body and contacting the first molded body. Development unit. A transmission member that is provided on one end side in the axial direction and transmits a driving force from the main body of the electrophotographic image forming apparatus to the shaft member;
The developing unit according to claim 1, wherein the second molded body has a second contact portion that contacts the end surface of the transmission member on the one end side in the axial direction .   The developing unit according to claim 2, wherein the transmission member is an Oldham coupling. By the convex portion protruding in a direction intersecting the axial direction with respect to said base portion, said first retaining portion, said a second retaining portion, claims 1, characterized in that is formed 4. The developing unit according to any one of 3 above. Oite the Direction said axis, said first retaining portion, said second retaining portion and any one of claims 1 to 3 wherein the base portion is characterized in that it is arranged between the The developing unit according to 1.   The developing unit according to claim 1, wherein the second molded body is a conductive resin.   A process cartridge comprising an electrophotographic photosensitive drum and the developing unit according to any one of claims 1 to 6, and detachable from an apparatus main body of the electrophotographic image forming apparatus.   An electrophotographic image forming apparatus comprising the process cartridge according to claim 5 and forming an image on a recording medium.