Patent Publication Number: US-10322580-B2

Title: Frame, cartridge, image forming apparatus, and method for manufacturing frame

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a frame of a cartridge detachably attached to an apparatus body of an image forming apparatus, a cartridge, an image forming apparatus that forms an image on a recording medium, and a method for manufacturing a frame of a cartridge. 
     Description of the Related Art 
     In an image forming apparatus which uses an electrophotographic technique, first, a photosensitive drum is charged uniformly by a charging roller. Subsequently, the charged photosensitive drum is selectively exposed, whereby an electrostatic latent image is formed on the photosensitive drum. The electrostatic latent image formed on the photosensitive drum is developed by a developing apparatus as a toner image. The toner image formed on the photosensitive drum is transferred to a recording material such as a recording sheet or a plastic sheet, and the toner image transferred to the recording material is fixed to the recording material by being heated and pressurized. Moreover, the toner remaining on the photosensitive drum after the toner image on the photosensitive drum is transferred to the recording material is removed by a cleaning blade. 
     Generally, in such an image forming apparatus, replenishment of toner, maintenance of various process mechanisms, and the like are required. In order to facilitate toner replenishment, maintenance, and the like, a process cartridge in which process mechanisms such as a photosensitive drum, a charging roller, a developing apparatus, and a cleaning blade are integrated as a cartridge has been in practical use. Since this process cartridge is detachably attached to an apparatus body of an image forming apparatus, replacement of a process mechanism, replenishment of toner, and the like can be performed easily by replacing the process cartridge. 
     According to this process cartridge system, since users can perform maintenance of an image forming apparatus by themselves, it is possible to improve operability remarkably and to provide an image forming apparatus having excellent usability. Due to this, the process cartridge system is employed broadly in an image forming apparatus. 
     Here, rollers such as a charging roller or a developing roller are often used in an image forming apparatus. In these rollers, a rotating shaft provided in the roller is rotatably supported by being fitted to a first supporting member attached to a frame. Here, conventionally, a first supporting member formed of two different types of resin materials is known as the first supporting member. When such a first supporting member is formed, first, a second supporting member that supports the first supporting member is formed using a first type of resin material by injection molding. Subsequently, another mold different from a mold used when the second supporting member is injection-molded is brought into close contact with the second supporting member, and a second type of resin material is injected into a gap between the mold and the second supporting member. In this manner, the first supporting member formed of the second type of resin material is attached to the second supporting member formed of the first type of resin material. Moreover, when the first supporting member is formed, the first supporting member may be attached to the second supporting member by injection-molding the second supporting member using the first type of resin material according to a two-color molding method and injecting the second type of resin material continuously without releasing the mold from the second supporting member. 
     By forming the first supporting member according to such a method, it is possible to use a resin having a conductivity, a sliding property, and the like as the material of the first supporting member that supports the rotating shaft of a roller and to use a high-rigidity resin material as the material of the second supporting member that supports the first supporting member. In this way, it is possible to manufacture the first supporting member having a high functionality at a low cost. For example, a configuration in which a first supporting member that rotatably supports a rotating shaft of a roller is formed of a conductive resin and electric power is supplied from an apparatus body of an image forming apparatus to the roller via the first supporting member having a conductivity is known (Japanese Patent Application Publication No. 2013-127575). 
     However, since members formed of two types of resin materials do not have a compatibility depending on a combination of the resin materials, a close-contact property between the first and second supporting members may decrease. In order to position the first supporting member in relation to the second supporting member with high accuracy, it is necessary to correct the position of a mold in relation to the second supporting member repeatedly. Moreover, when an impact is applied in the process of transporting a process cartridge, the first supporting member may be detached from the second supporting member. Due to this, in this technique, a tapered surface inclined in relation to a surface orthogonal to the axis of the center of rotation of a developing roller is formed on the first supporting member. In this way, the supporting accuracy of the first supporting member supporting the developing roller is improved, and the first supporting member is suppressed from being detached from the second supporting member during transporting of the process cartridge. 
     Specifically, a circular hole is formed in the second supporting member, and the first supporting member having a columnar shape is fitted into the hole. However, with a decrease in diameter of the photosensitive drum and the developing roller in recent years, the distance between the rotating shafts of the photosensitive drum and the developing roller has decreased. Due to this, in recent years, a circular penetration portion to which a first supporting member that supports a developing roller is fitted may interfere with a circular penetration portion to which the first supporting member that supports a photosensitive drum is fitted, and it is difficult to configure the penetration portion to which the first supporting member is fitted as a circular hole. Therefore, in recent years, in the circular penetration portion to which the first supporting member that supports the developing roller is fitted, a portion that interferes with the penetration portion to which the first supporting member that supports the photosensitive drum is fitted is removed. In this way, the inner wall surface of the penetration portion to which the first supporting member that supports the developing roller is fitted is not closed but open. That is, the inner wall surface of the penetration portion to which the first supporting member is fitted is not a circumferential surface but an arc surface. With such a configuration, even when the rotating shafts of the developing roller and the photosensitive drum are at a close distance, the developing roller and the photosensitive drum are rotatably supported. 
     However, when the inner wall surface of the penetration portion to which the first supporting member that supports the developing roller is fitted is open, the inner wall surface of the penetration portion may be open further due to deformation or thermal contraction of the second supporting member in which the penetration portion is formed. In this way, there is a concern that the first supporting member that supports a rotating member such as the developing roller is not positioned with satisfactory accuracy in relation to the second supporting member that supports the first supporting member and that the first supporting member is detached from the second supporting member. 
     SUMMARY OF THE INVENTION 
     A frame of cartridge that is detachably attached to an apparatus to an apparatus body of an image forming apparatus according to an embodiment of the present invention is a frame of a cartridge that is detachably attached to an apparatus body of an image forming apparatus, the frame comprising: 
     a first supporting member that rotatably supports a rotating member; and 
     a second supporting member that supports the first supporting member, wherein 
     the second supporting member includes an opening that partially exposes the first supporting member, a first engaged portion, and a second engaged portion, 
     the first supporting member is disposed to be adjacent to the second supporting member in a direction crossing an axial direction of the rotating member and supports the second supporting member, the first supporting member including a first engaging portion that engages with the first engaged portion and a second engaging portion that engages with the second engaged portion in a plane crossing the axial direction of the rotating member, 
     the first engaging portion is configured to apply force to the first engaged portion in a direction opposite to a direction in which the first engaged portion moves when the opening opens, and 
     the second engaging portion is configured to apply force to the second engaged portion in a direction opposite to a direction in which the second engaged portion moves when the opening opens. 
     A cartridge according to an embodiment of the present invention is a cartridge comprising: 
     the above described frame; 
     the rotating member; and 
     an image bearing member on which an electrostatic latent image is formed, wherein 
     the rotating member is a developing roller, and 
     a developer image is formed on the image bearing member by developing the electrostatic latent image formed on the image bearing member by the rotating member. 
     An image forming apparatus according to an embodiment of the present invention is an image forming apparatus comprising: 
     the above described frame; 
     an image bearing member on which an electrostatic latent image is formed; and 
     the rotating member, wherein 
     the rotating member is a developer bearing member for bearing a developer, 
     a developer image is formed on the image bearing member by developing the electrostatic latent image formed on the image bearing member by the developer borne on the rotating member, and 
     an image is formed on the recording medium by transferring, to a recording medium, the developer image formed on the image bearing member. 
     A method for manufacturing a frame of a cartridge that is detachably attached to an apparatus body of an image forming apparatus according to an embodiment of the present invention is a method for manufacturing a frame of a cartridge that is detachably attached to an apparatus body of an image forming apparatus, 
     the frame including a first supporting member that rotatably supports a rotating member, and a second supporting member that supports the first supporting member, 
     the second supporting member including an opening that partially exposes the first supporting member, a first engaged portion, and a second engaged portion, 
     the first supporting member being disposed to be adjacent to the second supporting member in a direction crossing an axial direction of the rotating member and supported by the second supporting member, the first supporting member including a first engaging portion that engages with the first engaged portion and a second engaging portion that engages with the second engaged portion in a plane crossing the axial direction of the rotating member, 
     the first engaging portion being configured to apply force to the first engaged portion in a direction opposite to a direction in which the first engaged portion moves when the opening opens, and 
     the second engaging portion being configured to apply force to the second engaged portion in a direction opposite to a direction in which the second engaged portion moves when the opening opens, 
     the method comprising: 
     bringing a mold into contact with the second supporting member and injecting a molten resin into a space formed between the second supporting member and the mold to form the first supporting member. 
     A frame of a cartridge that is detachably attached to an apparatus body of an image forming apparatus according to an embodiment of the present invention is a frame of a cartridge that is detachably attached to an apparatus body of an image forming apparatus, the frame comprising: 
     a first supporting member having a bearing portion that rotatably supports a rotating member; and 
     a second supporting member that supports the first supporting member, wherein 
     in a cross-section orthogonal to an axial direction of the rotating member, the second supporting member has an opening that partially exposes a contour of the first supporting member, and is provided with the first engaged portion on one side thereof and the second engaged portion on the other side thereof in relation to a straight line that connects the center of rotation of the rotating member and a midpoint of the opening, and 
     in the cross-section orthogonal to the axial direction of the rotating member, the first supporting member includes a first engaging portion that engages with the first engaged portion and a second engaging portion that engages with the second engaged portion, the first and second engaging portions being convex portions that protrude from the bearing portion. 
     Further features of the present invention will become apparent from the following description of exemplary embodiments (with reference to the attached drawings). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A to 1E  are cross-sectional views illustrating a method for manufacturing a first resin portion according to a first embodiment. 
         FIG. 2  is a schematic cross-sectional view illustrating an image forming apparatus according to the first embodiment. 
         FIG. 3  is a schematic cross-sectional view of a cartridge according to the first embodiment. 
         FIG. 4  is a cross-sectional view of a cleaning frame of the cartridge according to the first embodiment. 
         FIG. 5  is a diagram illustrating an open state of an opening door of an apparatus body of the image forming apparatus according to the first embodiment. 
         FIG. 6  is a diagram illustrating a state in which a tray is drawn from the apparatus body of the image forming apparatus according to the first embodiment. 
         FIG. 7  is a diagram illustrating a state in which the cartridge is attached to or detached from the tray according to the first embodiment. 
         FIG. 8  is a perspective view of the cartridge according to the first embodiment when seen from a driving-side board side. 
         FIG. 9  is a perspective view of the cartridge according to the first embodiment when seen from a non-driving-side board. 
         FIG. 10  is an exploded view of the cartridge according to the first embodiment. 
         FIG. 11  is a perspective view of the cartridge according to the first embodiment. 
         FIG. 12  is an exploded view of the cartridge according to the first embodiment. 
         FIG. 13  is an exploded view of the cartridge according to the first embodiment. 
         FIGS. 14A and 14B  are external views illustrating a first supporting member and a second supporting member according to the first embodiment. 
         FIGS. 15A and 15B  are diagrams illustrating the second supporting member according to the first embodiment. 
         FIGS. 16A and 16B  are diagrams illustrating the first supporting members according to the first embodiment. 
         FIGS. 17A to 17E  are cross-sectional views illustrating a method for manufacturing a first supporting member according to a second embodiment. 
         FIG. 18  is a diagram illustrating a modification of the first and second supporting member according to the first embodiment. 
         FIG. 19  is a diagram illustrating a modification of the first and second supporting member according to the first embodiment. 
         FIG. 20  is a diagram illustrating a first supporting member according to a third embodiment. 
         FIG. 21  is a diagram illustrating a first supporting member and a second supporting member according to a fourth embodiment. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Hereinafter, a description will be given, with reference to the drawings, of embodiments of the present invention. However, the sizes, materials, shapes, their relative arrangements, or the like of constituents described in the embodiments may be appropriately changed according to the configurations, various conditions, or the like of apparatuses to which the invention is applied. Therefore, the sizes, materials, shapes, their relative arrangements, or the like of the constituents described in the embodiments do not intend to limit the scope of the invention to the following embodiments. 
     First Embodiment 
     Hereinafter, an embodiment will be described in detail with reference to the drawings. In the present embodiment, an axial direction of the center of rotation of an electrophotographic photosensitive drum (hereinafter referred to as a drum  62 ) as an image bearing member is defined as a longitudinal direction. In this longitudinal direction, a side on which the drum  62  receives driving force from an apparatus body A of an image forming apparatus S is defined as a driving side and the opposite side is defined as a non-driving side. First, an overall configuration and an image forming process of an image forming apparatus will be described with reference to  FIGS. 2 and 3 .  FIG. 2  is a schematic cross-sectional view illustrating the image forming apparatus S according to the first embodiment.  FIG. 3  is a schematic cross-sectional view of a cartridge B according to the first embodiment. Here, the apparatus body A is a portion of the image forming apparatus S excluding the cartridge B. 
     &lt;Overall Configuration of Image Forming Apparatus&gt; 
     The image forming apparatus S illustrated in  FIG. 2  is a laser beam printer which uses an electrophotographic technique and in which the cartridge B is detachably attached to the apparatus body A. An exposure apparatus  3  (a laser scanner unit) for forming an electrostatic latent image on a drum  62  in the cartridge B is disposed in the image forming apparatus S. Moreover, a sheet tray  4  in which sheet P which is a recording medium is stored is disposed on a lower side of the cartridge B. Moreover, a pickup roller  5   a , a feed roller pair  5   b , a conveying roller pair  5   c , a transfer guide  6 , a transfer roller  7 , a conveying guide  8 , a fixing apparatus  9 , a discharge roller pair  10 , a discharge tray  11 , and the like are sequentially disposed in the apparatus body A along a conveying direction D of the sheet P. The fixing apparatus  9  includes a heating roller  9   a  and a pressure roller  9   b.    
     &lt;Image Forming Process&gt; 
     Next, an image forming process will be described. When an image forming process is executed, first, the drum  62  rotates at a predetermined circumferential velocity (a process speed) in the direction indicated by arrow R on the basis of a print start signal. Moreover, a charging roller  66  to which a bias voltage is applied makes contact with an outer circumferential surface of the drum  62  to charge the outer circumferential surface of the drum  62  uniformly. The exposure apparatus  3  outputs a laser beam M according to image information. The laser beam M passes through a laser opening  71   h  formed in a cleaning frame  71  of the cartridge B to scan and expose the outer circumferential surface of the drum  62 . In this way, an electrostatic latent image corresponding to the image information is formed on the outer circumferential surface of the drum  62 . 
     On the other hand, as illustrated in  FIG. 3 , in a developing unit  20  serving as a developing apparatus, toner T in a toner chamber  29  is delivered to a toner supply chamber  28  by being stirred and conveyed with rotation of a first conveying member  43 , a second conveying member  44 , and a third conveying member  50 . The toner T is born on the surface of a developing roller  32  (corresponding to a rotating member and a developer bearing member) by magnetic force of a magnet roller (a fixed magnet). The toner T is triboelectrically charged by a developing blade  42  and the thickness of the toner T on the outer circumferential surface of the developing roller  32  is regulated. The toner T adheres to the electrostatic latent image formed on the drum  62 , whereby the electrostatic latent image formed on the drum  62  is developed as a toner image serving as a developer image. 
     Moreover, as illustrated in  FIG. 2 , the sheet P as a recording medium stored in a lower portion of the apparatus body A is delivered from the sheet tray  4  by the pickup roller  5   a , the feed roller pair  5   b , and the conveying roller pair  5   c  in synchronization with the timing at which the laser beam M is output. The sheet P is guided to the transfer guide  6  and is conveyed to a transfer position between the drum  62  and the transfer roller  7 . At this transfer position, the toner image is sequentially transferred from the drum  62  to the sheet P. 
     The sheet P to which the toner image is transferred is separated from the drum  62 , guided by the conveying guide  8 , and conveyed to the fixing apparatus  9 . The sheet P passes through a nip portion between the heating roller  9   a  and the pressure roller  9   b  of the fixing apparatus  9 . At this nip portion, the sheet P is pressurized and heated whereby the toner image is fixed to the sheet P. The sheet P to which the toner image is fixed is conveyed toward the discharge roller pair  10  and is discharged to the discharge tray  11  by the discharge roller pair  10 . 
     On the other hand, as illustrated in  FIG. 3 , residual toner remaining on the surface of the drum  62  after the toner image is transferred to the sheet P is removed by a cleaning member  77  and is used again for an image forming process. The residual toner removed from the drum  62  is stored in the toner chamber  71   b  of a cleaning unit  60 . In the above description, the charging roller  66 , the developing roller  32 , the transfer roller  7 , the cleaning member  77 , and the like are process mechanisms that act on the drum  62 . 
     &lt;Attachment and Detachment of Cartridge B&gt; 
     Next, attachment and detachment of the cartridge B to and from the apparatus body A will be described with reference to  FIGS. 5 to 8 .  FIG. 5  is a diagram illustrating an open state of an opening door  13  of the apparatus body A of the image forming apparatus S according to the first embodiment.  FIG. 6  is a diagram illustrating a state in which the tray  18  is drawn from the apparatus body A of the image forming apparatus S according to the first embodiment.  FIG. 7  is a diagram illustrating a state in which the cartridge B is attached to and detached from the tray  18  according to the first embodiment. Here, the cartridge B can be attached to and detached from the tray  18  along an attachment and detachment direction E. 
     The opening door  13  is pivotably attached to the apparatus body A, and a cartridge insertion opening  17  is exposed when the opening door  13  is open. The tray  18  for attaching the cartridge B to the apparatus body A is provided in the cartridge insertion opening  17 . When the tray  18  is drawn up to a predetermined position, the cartridge B can be detached from and attached to the tray  18 . Moreover, the cartridge B is attached to the apparatus body A while being guided by a guide rail (not illustrated) in a state of being mounted on the tray  18 . 
     As illustrated in  FIG. 8 , a first drive shaft  14  and a second drive shaft  19  for respectively transmitting driving force to a first coupling  70  and a second coupling  21  provided in the cartridge B are formed in the apparatus body A. The first and second drive shafts  14  and  19  are driven by a motor (not illustrated) provided in the apparatus body A. In this way, the drum  62  coupled to the first coupling  70  rotates in response to the driving force from the apparatus body A. Moreover, the developing roller  32  rotates when driving force is transmitted from the second coupling  21 . Furthermore, a power feeding unit (not illustrated) of the apparatus body A feeds electric power to the charging roller  66  and the developing roller  32 . 
     &lt;Configuration for Supporting Cartridge B&gt; 
     As illustrated in  FIG. 5 , a driving-side board  15  and a non-driving-side board  16  for supporting the cartridge B are provided in the apparatus body A. Here,  FIG. 8  is a diagram illustrating a side of the cartridge B according to the first embodiment, which is supported by the driving-side board  15 .  FIG. 9  is a diagram illustrating a side of the cartridge B according to the first embodiment, which is supported by the non-driving-side board  16 . As illustrated in  FIG. 8 , a first driving-side supporting portion  15   a , a second driving-side supporting portion  15   b , and a rotation supporting portion  15   c  of the cartridge B are provided in the driving-side board  15 . Moreover, as illustrated in  FIG. 9 , a first non-driving-side supporting portion  16   a , a second non-driving-side supporting portion  16   b , and a rotation supporting portion  16   c  are provided in the non-driving-side board  16 . 
     On the other hand, a supported portion  73   b  and a supported portion  73   d  of a drum bearing  73  are provided in the cartridge B, and a driving-side boss  71   a , a non-driving-side protrusion  71   f , and a non-driving-side boss  71   g  of the cleaning frame  71  are provided. The supported portion  73   b  is supported by the first driving-side supporting portion  15   a , the supported portion  73   d  is supported by the second driving-side supporting portion  15   b , and the driving-side boss  71   a  is supported by the rotation supporting portion  15   c . Moreover, the non-driving-side protrusion  71   f  is supported by the first and second non-driving-side supporting portions  16   a  and  16   b , and the non-driving-side boss  71   g  is supported by the rotation supporting portion  16   c , whereby the cartridge B is positioned within the apparatus body A. 
     &lt;Overall Configuration of Cartridge B&gt; 
     Next, an overall configuration of the cartridge B will be described with reference to  FIGS. 3, 4, 10, 11, 12, and 13 . Here,  FIG. 10  is an exploded view of the cartridge B according to the first embodiment.  FIG. 11  is a perspective view of the cartridge B according to the first embodiment.  FIG. 12  is an exploded view of the cartridge B according to the first embodiment.  FIG. 13  is an exploded view of the cartridge B according to the first embodiment.  FIGS. 11 and 13  are enlarged views of portions surrounded by dot lines in  FIGS. 10 and 12  when seen at different angles. In the present embodiment, the description of screws used when coupling respective components of the cartridge B will be omitted. 
     As illustrated in  FIGS. 3 and 10 , the cartridge B includes a cleaning unit  60  and a developing unit  20 . The cartridge B has a configuration in which the drum  62  and at least one of the charging roller  66 , the developing unit  20 , and the cleaning unit  60  as the process mechanisms that act on the drum  62  are integrated with each other as a cartridge. Moreover, the cartridge B is detachably attached to the apparatus body A of the image forming apparatus S. In the present embodiment, the cartridge B includes at least the cleaning unit  60 . 
     The cleaning unit  60  has the drum  62 , the charging roller  66 , the cleaning member  77 , and a cleaning frame  71  that supports these components, and a lid member  72  fixed to the cleaning frame  71  by welding or the like. In the cleaning unit  60 , the charging roller  66  and the cleaning member  77  are in contact with the outer circumferential surface of the drum  62 . 
     The cleaning member  77  has a rubber blade  77   a  which is a blade-shaped elastic member formed of rubber as an elastic material and a supporting member  77   b  that supports the rubber blade. The rubber blade  77   a  is in contact with the drum  62  in a counter direction in relation to the rotation direction of the drum  62 . That is, the rubber blade  77   a  is in contact with the drum  62  so that the distal end of the rubber blade  77   a  faces the upstream side in the rotation direction of the drum  62 . 
     As illustrated in  FIGS. 3 and 4 , waste toner removed from the surface of the drum  62  by the cleaning member  77  is conveyed by a first screw  86 , a second screw  87 , and a third screw  88  as a waste toner conveying member. The waste toner is accumulated in a waste toner chamber  71   b  formed by the cleaning frame  71  and the lid member  72 . Moreover, the first screw  86  rotates in response to driving force transmitted from the coupling  21  illustrated in  FIG. 13  via a gear (not illustrated). The second screw  87  rotates in response to driving force transmitted from the first screw  86 , and the third screw  88  rotates in response to driving force transmitted from the second screw  87 . 
     The first screw  86  is disposed near the drum  62 , the second screw  87  is disposed at the end in the longitudinal direction of the cleaning frame  71 , and the third screw  88  is disposed in the waste toner chamber  71   b . Here, the axes of the center of rotation of the first and third screws  86  and  88  are parallel to the axis of the center of rotation of the drum  62 , and the axis of the center of rotation of the second screw  87  is orthogonal to the axis of the center of rotation of the drum  62 . As illustrated in  FIG. 3 , a scooping sheet  65  for preventing leakage of waste toner from the cleaning frame  71  is provided at an edge of the cleaning frame  71  so as to make contact with the drum  62 . 
     The drum  62  rotates in the direction indicated by arrow R according to an image forming operation in response to driving force from a body driving motor (not illustrated) which is a driving source. Moreover, the charging roller  66  is rotatably attached to the cleaning unit  60  with the aid of a charging roller bearing  67  at both ends in the longitudinal direction (approximately parallel to the axial direction of the center of rotation of the drum  62 ) of the cleaning frame  71 . The charging roller  66  is configured such that the charging roller bearing  67  is pressed toward the drum  62  by the biasing member  68 . In this way, the charging roller  66  presses the drum  62 . The charging roller  66  rotates following the rotation of the drum  62 . 
     As illustrated in  FIG. 3 , the developing unit  20  has the developing roller  32 , a developing container  23  that supports the developing roller  32 , a developing blade  42 , and the like. A magnet roller  34  is provided in the developing roller  32 . Moreover, a developing blade  42  for regulating a toner layer on the developing roller  32  is disposed in the developing unit  20 . As illustrated in  FIGS. 10 and 12 , an interval holding member  38  is attached to both ends of the developing roller  32  and the interval holding member  38  is in contact with the drum  62 , whereby a small gap is formed between the developing roller  32  and the drum  62 . 
     As illustrated in  FIG. 3 , a blowout preventing sheet  33  for preventing leakage of toner from the developing unit  20  is provided at an edge of a bottom member  22  so as to make contact with the developing roller  32 . Furthermore, a first conveying member  43 , a second conveying member  44 , and a third conveying member  50  are provided in the toner chamber  29  formed by the developing container  23  and the bottom member  22 . The first, second, and third conveying members  43 ,  44 , and  50  stir the toner stored in the toner chamber  29  and convey the toner to the toner supply chamber  28 . 
     As illustrated in  FIGS. 10 and 11 , the cartridge B is formed by combining the cleaning unit  60  and the developing unit  20 . The cleaning frame  71 , the lid member  72 , the drum  62 , a drum bearing  73  for rotatably supporting the drum  62 , and a drum shaft  78  are provided in the cleaning unit  60 . As illustrated in  FIG. 13 , on the side of the driving-side board  15 , the drum  62  is rotatably supported when a driving-side drum flange  63  provided on the side of the driving-side board  15  is fitted to a hole  73   a  of the drum bearing  73 . On the other hand, as illustrated in  FIG. 10 , on the side of the non-driving-side board  16 , the drum shaft  78  press-fitted to a hole  71   c  formed in the cleaning frame  71  rotatably supports the hole (not illustrated) of a non-driving-side drum flange  64 . 
     As illustrated in  FIGS. 3, 10, and 12 , the developing unit  20  includes the bottom member  22 , the developing container  23 , a driving-side developing side member  26 , the developing blade  42 , the developing roller  32 , and the like. The developing roller  32  is rotatably supported by a bearing member  27  and a bearing member  37  provided at both ends of the developing roller  32 . As illustrated in  FIGS. 11 and 13 , the cleaning unit  60  and the developing unit  20  are pivotably coupled by a coupling pin  69 , whereby the cartridge B is formed. 
     Specifically, as illustrated in  FIGS. 10 and 12 , a first developing support hole  23   a  and a second developing support hole  23   b  are formed in the developing container  23  at both ends in the longitudinal direction of the developing unit  20 . As illustrated in  FIGS. 10, 12, and 13 , a first suspension hole  71   i  and a second suspension hole (not illustrated) are formed in the cleaning frame  71  at both ends in the longitudinal direction of the cleaning unit  60 . The coupling pins  69  press-fitted to the first suspension hole  71   i  and the second suspension hole (not illustrated) are fitted to the first and second developing support holes  23   a  and  23   b  whereby the cleaning unit  60  and the developing unit  20  are coupled in a pivotable manner. 
     As illustrated in  FIG. 13 , a first hole  46 Ra of a driving-side biasing member  46 R is caught at a boss  73   c  of the drum bearing  73 , and a second hole  46 Rb is caught at a boss  26   a  of the driving-side developing side member  26 . As illustrated in  FIGS. 10 and 12 , a first hole (not illustrated) of a non-driving-side biasing member  46 F is caught at a boss (not illustrated) of the cleaning frame  71 , and a second hole (not illustrated) of the biasing member  46 F is caught at a boss  37   a  of the bearing member  37 . 
     In the present embodiment, the driving-side biasing member  46 R and the non-driving-side biasing member  46 F are formed of a tension spring, and the developing unit  20  is biased toward the cleaning unit  60  by the biasing force of the spring. In this way, the developing roller  32  is reliably pressed toward the drum  62 . Moreover, a predetermined interval is formed between the developing roller  32  and the drum  62  by the interval holding member  38  attached to both ends of the developing roller  32 . 
     &lt;Configuration of Bearing Member  37 &gt; 
     Next, the bearing member  37  that supports the developing roller  32  of the cartridge B according to the present embodiment will be described with reference to  FIGS. 14A and 14B, 15A and 15B, and 16A and 16B .  FIGS. 14A and 14B  are external views illustrating the bearing member  37  according to the first embodiment.  FIGS. 15A and 15B  are diagrams illustrating a first resin portion  39  as the second supporting member according to the first embodiment.  FIGS. 16A and 16B  are diagrams illustrating a second resin portion  40  as the first supporting member according to the first embodiment. The first and second resin portions  39  and  40  are formed of different materials, the second resin portion  40  is formed of a conductive resin, and current flows through the developing roller  32  via the second resin portion  40  having a conductivity. Moreover, the material that forms the first resin portion  39  is cheaper than the material that forms the second resin portion  40 . 
       FIG. 14A  is a view when the bearing member  37  is seen from the non-driving-side board  16  and  FIG. 14B  is a view when the bearing member  37  is seen from the opposite direction from  FIG. 14A . As illustrated in  FIG. 14A , the bearing member  37  that rotatably supports the developing roller  32  includes the first resin portion  39  as a supporting member and the second resin portion  40  as a pivotably support member. As illustrated in  FIGS. 15A and 15B , a holding portion  39   a , an opening  39   b , and a latched portion  39   c  (corresponding to a first engaged portion and a second engaged portion) are formed in the first resin portion  39 . The opening  39   b  is a gap formed so that the inner wall of the penetration portion formed in the first resin portion  39  is discontinuous. In this manner, in the direction crossing the axial direction of the center of rotation of the developing roller  32 , the first resin portion  39  is disposed to be adjacent to the second resin portion  40  so as to support the second resin portion  40 . On the other hand, the first resin portion  39  has an opening  39   b  that partially exposes the second resin portion  40  (more specifically, a contour of the second resin portion  40 ). 
     As illustrated in  FIGS. 16A and 16B , a pivotably support portion  40   a  and a latching portion  40   b  (corresponding to a first engaging portion and a second engaging portion) are integrally formed in the second resin portion  40 . The second resin portion  40  is attached to the first resin portion  39  by being fitted to the penetration portion formed in the first resin portion  39 . Moreover, the latching portion  40   b  extends in a direction orthogonal to a direction in which the second resin portion  40  is fitted to the first resin portion  39 . The extension direction of one latching portion  40   b  is opposite to the extension direction of the other latching portion  40   b.    
     As illustrated in  FIGS. 15A and 15B , a holding portion  39   a  of the first resin portion  39  is arranged around the pivotably support portion  40   a  in a plane orthogonal to the axial direction of the center of rotation of the developing roller  32  so as to support the pivotably support portion  40   a . The holding portion  39   a  is disposed so as to be parallel to the pivotably support portion  40   a  in the direction crossing the axis of the center of rotation of the developing roller  32  to support the pivotably support portion  40   a . In addition, the holding portion  39   a  has a convex portion extending in the direction crossing the axis of the center of rotation, and restricts the movement of the pivotably support portion  40   a  along the axis of the center of rotation. More specifically, the holding portion  39   a  has a convex portion extending toward the axis of the center of rotation and the pivotably support portion  40   a  engages with the convex portion to restrict the movement along the axis of the center of rotation. Moreover, the opening  39   b  is formed in the holding portion  39   a  so that the drum  62  can further approach the developing roller  32 , and a portion exposed from the opening  39   b  is notched. As illustrated in  FIG. 15A , the latched portions  39   c  are provided in respective regions divided by a straight line F that connects the center of rotation J of the developing roller  32  and the midpoint K of the opening  39   b.    
     In the present embodiment, the opening  39   b  extends in the rotational direction of the developing roller  32  at a predetermined interval. In a plane orthogonal to the axis of the center of rotation of the developing roller  32 , one latched portion  39   c  is provided on one side of the first resin portion  39  in relation to the straight line that connects the axis of the center of rotation of the developing roller  32  and the midpoint of the opening  39   b . Moreover, the other latched portion  39   c  is provided on the other side of the first resin portion  39  in relation to the straight line that connects the axis of the center of rotation of the developing roller  32  and the midpoint of the opening  39   b . The latching portion  40   b  applies force to the latched portion  39   c  in the direction opposite to the direction in which the latched portion  39   c  moves when the opening  39   b  opens. More specifically, the latching portion  40   b  applies force to the latched portion  39   c  so that the opening  39   b  is closed when the first resin portion  39  is deformed so that the opening  39   b  opens. 
     Here, as illustrated in  FIG. 14A , W is defined as a straight line that connects the center of rotation J of the developing roller  32  and a centroid L of the latching portion  40   b . The latching portion  40   b  has a large width portion and a small width portion. The large width portion is positioned away from the small width portion in the direction of the straight line W. Specifically, the center of rotation J, the small width portion, and the large width portion are arranged in that order in the direction of the straight line W, that is, the direction away from the center of rotation J). 
     A straight line that is parallel to the straight line W and follows an outer shape of the small width portion of the latching portion  40   b  is defined as a straight line w 1 , and a straight line that follows an outer shape of the large width portion of the latching portion  40   b  is defined as a straight line w 2 . As illustrated in  FIGS. 14A and 14B , the straight line w 1  is at the shortest distance from the straight line W among the straight lines that make contact with the outer shape of the latching portion  40   b . Moreover, the straight line w 2  is at the longest distance from the straight line W among the straight lines that make contact with the outer shape of the latching portion  40   b . A contacted portion  39   d  of the first resin portion  39  and a contact portion  40   c  of the second resin portion  40  are provided in a region sandwiched by the straight lines w 1  and w 2 . The shape of the latching portion  40   b  and the latched portion  39   c  may be circular as illustrated in  FIG. 18  and may be triangular as illustrated in  FIG. 19 , for example. The shape of the latching portion  40   b  and the latched portion  39   c  is not particularly limited as long as the condition (the relation with the straight lines w 1  and w 2 ) is satisfied. In the present embodiment, the frictional coefficient of the second resin portion  40  is smaller than the frictional coefficient of the first resin portion  39 . Specifically, when the first and second resin portions  39  and  40  have respective portions having the same shape, the frictional coefficient of the second resin portion  40  is smaller than the frictional coefficient of the first resin portion  39  in the portion having the same shape. 
     &lt;Steps of Forming Bearing Member  37 &gt; 
     Next, steps of forming the bearing member  37  will be described with reference to  FIGS. 1A to 1E .  FIGS. 1A to 1E  schematically illustrate cross-sections taken along line A-A in  FIG. 14A . As illustrated in  FIG. 1A , when the bearing member  37  is formed, a mold  51  is brought into contact with the first resin portion  39  that is formed using another mold. In this case, a mold contact surface  39   e  of the first resin portion  39  abuts on a contact surface  51   a  of the mold  51 . 
     Subsequently, as illustrated in  FIG. 1B , the mold  52  is brought into contact with the first resin portion  39 . In this case, the mold contact surface  39   f  of the first resin portion  39  abuts on the contact surface  52   a  of the mold  52  contacting the first resin portion  39 .  FIG. 1C  illustrates a state in which the two molds  51  and  52  are brought into contact with the first resin portion  39  so as to sandwich the first resin portion  39 . The first resin portion  39  is positioned by the molds  51  and  52  (not illustrated). In this case, the holding portion  39   a  of the first resin portion  39  and the molds  51  and  52  form a pivotably-support-portion-forming space  54 . The latched portion  39   c  of the first resin portion  39  is disposed to face the mold  52  with a latching portion-forming space  55  interposed therebetween. 
     Subsequently, a gate  53  for injecting a second resin is brought into contact with an injection opening  52   b  of the mold  52 . The gate  53  and the mold  52  may be initially integrated with each other. After that, as illustrated in  FIG. 1D , the second resin enters from the gate  53  into the pivotably support-portion-forming space  54  and the latching portion-forming space  55  through the injection opening  52   b , whereby the pivotably support portion  40   a  and the latching portion  40   b  which form the second resin portion  40  are formed. 
     When injection of the second resin is completed, the molds  51  and  52  are separated from the bearing member  37 . Separation of the molds  51  and  52  is performed in the order reverse to the order of attaching the molds  51  and  52  to the first resin portion  39 . First, the gate  53  is retracted from the injection opening  52   b  of the mold  52 . Subsequently, the mold  52  is released from the first and second resin portions  39  and  40 , and finally, the mold  51  is released from the first and second resin portions  39  and  40 . In this way, as illustrated in  FIG. 1E , the bearing member  37  in which the first and second resin portions  39  and  40  are integrally formed is formed. 
     The second resin portion formed in this manner is thermally contracted after being formed. Specifically, the second resin solidifies and the second resin portion  40  is thermally contracted whereby the latching portion  40   b  applies force to the latched portion  39   c  in the direction in which the opening  39   b  is closed. Due to this, as illustrated in  FIG. 14A , the contact portion  40   c  formed in the latching portion  40   b  of the second resin portion  40  is contracted in the direction indicated by arrow H. Moreover, since the contact portion  40   c  is in contact with the contacted portion  39   d  of the first resin portion  39 , the contacted portion  39   d  is pressed by the contact portion  40   c  in the direction indicated by arrow H. In this way, since it is possible to suppress the opening  39   b  of the first resin portion  39  from opening in the direction indicated by arrow G, the positional accuracy of the holding portion  39   a  of the first resin portion  39  becomes stable. Due to this, the positional accuracy of the pivotably support portion  40   a  of the second resin portion  40  becomes stable. In the present embodiment, functions, materials, shapes, relative positions, and the like of constituent components are examples only, and unless otherwise specified, the scope of this invention is not to be limited thereto. 
     As described above, in the present embodiment, the latching portion  40   b  applies force to the latched portion  39   c  in the direction opposite to the direction in which the latched portion  39   c  moves when the opening  39   b  opens. Due to this, it is possible to suppress the opening  39   b  from opening and to suppress the second resin portion  40  from being separated from the first resin portion  39 . That is, the second resin portion  40  that supports the developing roller  32  can be positioned with high accuracy in relation to the first resin portion  39  that supports the second resin portion  40 . 
     In the present embodiment, the material that forms the first resin portion  39  is cheaper than the material that forms the second resin portion  40 . Due to this, it is possible to reduce the manufacturing cost of the image forming apparatus S further than when the first and second resin portions  39  and  40  are manufactured using the material that forms the second resin portion  40 . 
     In the present embodiment, a molten resin solidifies and the second resin portion  40  is thermally contracted whereby the latching portion  40   b  applies force to the latched portion  39   c  in the direction in which the opening  39   b  is closed. In this way, since it is possible to suppress the opening  39   b  of the first resin portion  39  from opening, it is possible to suppress the second resin portion  40  from being separated from the first resin portion  39 . 
     Second Embodiment 
     Next, steps of forming the bearing member  37  that supports the developing roller  32  of the cartridge B according to a second embodiment will be described with reference to  FIGS. 17A to 17E . Here, in the present embodiment, portions having the same functions as those of the first embodiment will be denoted by the same reference numerals and the description thereof will be omitted. The bearing member  37  according to the present embodiment has the same shape as the bearing member  37  according to the first embodiment. 
     As illustrated in  FIG. 17A , molds  56   a ,  56   b , and  57  are brought into contact with each other to form a first resin-portion-forming space  90 . Subsequently, as illustrated in  FIG. 17B , a gate  59  is brought into contact with an injection opening  57   a  of the mold  57 . In this case, the mold  57  and the gate  59  may be initially integrated with each other. The first resin is injected from the gate  59  into the first resin-portion-forming space  90  whereby the first resin portion  39  is formed. 
     Subsequently, as illustrated in  FIG. 17C , the gate  59  is retracted from the injection opening  57   a , and the mold  57  is released from the molds  56   a  and  56   b  and the first resin portion  39 . After that, as illustrated in  FIG. 17D , the mold  56   b  is retracted by a distance corresponding to the thickness of the second resin portion  40 , and a mold  58  is brought into contact with a mold contact surface  39   f . In this way, the mold  56   a ,  56   b , and  58  and the first resin portion  39  form a second resin-portion-forming space  91 . 
     Subsequently, as illustrated in  FIG. 17E , the gate  92  is brought into contact with the injection opening  58   a  of the mold  58 , and the second resin is injected from the gate  92  into the second resin-portion-forming space  91 . In this way, the second resin portion  40  is formed. After injection of the second resin is completed, the molds  56   a ,  56   b , and  58  are separated from the bearing member  37 . Specifically, first, the gate  92  is retracted from the injection opening  58   a  of the mold  58 . Subsequently, the mold  58  is released from the first and second resin portions  39  and  40 . Finally, the molds  56   a  and  56   b  are released from the first and second resin portions  39  and  40 . In this manner, forming of the bearing member  37  is completed. Using such a forming method, it is possible to enhance the injection pressure when injecting a resin into a mold. Due to this, it is possible to maintain the position of the pivotably support portion  40   a  of the second resin portion  40  with higher accuracy. 
     Third Embodiment 
     Next, a third embodiment will be described with reference to  FIG. 20 . In the present embodiment, a bearing member  237  formed using two different types of resin materials will be described. Here, in the present embodiment, portions having the same functions as those of the first embodiment will be denoted by the same reference numerals, and the description thereof will be omitted. In the present embodiment, constituent components different from those of the first embodiment will be described mainly. 
       FIG. 20  is a diagram illustrating a bearing member  237  according to the third embodiment. In the present embodiment, a latched portion  239   c  of a first resin portion  239  and a latching portion  240   b  of a second resin portion  240  have a wavy shape. Specifically, the latched portion  239   c  and the latching portion  240   b  have a wavy shape in relation to a straight line W 2  that connects the center of rotation J of the developing roller  32  and the centroid L 2  of the latching portion  240   b . Using such a shape, it is possible to increase the number of portions of a contacted portion  239   d  of the first resin portion  239  applying force to the contact portion  240   c  of the second resin portion  240 . In this way, it is possible to more stably suppress the holding portion  39   a  from opening. Due to this, it is possible to further improve the positional accuracy of the pivotably support portion  40   a.    
     Fourth Embodiment 
     Next, a fourth embodiment will be described with reference to  FIG. 21 . Here, in the present embodiment, portions having the same functions as those of the first embodiment will be denoted by the same reference numerals and the description thereof will be omitted. In the first embodiment, the contacted portion  39   d  of the first resin portion  39  and the contact portion  40   c  of the second resin portion  40  extend in the direction of the plane orthogonal to the axial direction of the center of rotation of the developing roller  32 . In contrast, in the present embodiment, a latched portion  339   c  of a first resin portion  339  and a latching portion  340   b  of a second resin portion  340  extend in the axial direction of the center of rotation of the developing roller  32 . 
       FIG. 21  is a diagram illustrating a bearing member  337  according to the fourth embodiment. Specifically,  FIG. 21  is a cross-sectional view when the bearing member  337  is cut along a plane parallel to the axial direction of the center of rotation of the developing roller  32 . In the present embodiment, the latching portion  340   b  of the second resin portion  340  has a convex shape that protrudes in the axial direction of the center of rotation of the developing roller  32 . The first resin portion  339  also has a shape that follows the second resin portion  340 . Due to this, since it is not necessary to form the latched portion  339   c  and the latching portion  340   b  to extend along the plane orthogonal to the axis of the center of rotation of the developing roller  32 , it is possible to reduce the size of the bearing member  337  in the plane orthogonal to the axis of the center of rotation of the developing roller  32 . Moreover, since the size of the bearing member  337  in the plane orthogonal to the axis of the center of rotation of the developing roller  32  is reduced, it is possible to increase the space in the image forming apparatus S. 
     While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions. 
     This application claims the benefit of Japanese Patent Application No. 2016-118265, filed on Jun. 14, 2016, which is hereby incorporated by reference herein in its entirety.