Abstract:
A developing cartridge is provided for use with an image forming apparatus and may include a housing, a developing roller rotatably provided in the housing, and a developing roller gear configured to rotate integrally with the developing roller. Further, the developing cartridge can include a driving input gear configured to receive an external driving force and apply the received driving force to the developing roller gear. The driving input gear can be meshed with the developing roller gear or an intermediate gear can be provided to mesh with the developing roller gear and the driving input gear. Such an intermediate gear can be configured to apply the received driving force to the developing roller gear. Also, the developing cartridge can include a receiving member which is disposed between the housing and the developing roller gear and between the housing and the driving input gear.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of prior U.S. application Ser. No. 13/431,741, filed Mar. 27, 2012, which claims priority from Japanese Patent Application No. 2011-129977, filed on Jun. 10, 2011, the entire subject matter of which is incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    The disclosure relates to a developing cartridge which is provided with a developing roller and a gear which transmits driving force to the developing roller. 
         [0003]    A developing cartridge provided with a developing roller, a developing roller gear which rotates integrally with the developing roller, and a driving input gear which applies driving force to the developing roller gear is known (for example, see Japanese Unexamined Patent Application Publication No. 2010-134330). 
         [0004]    In particular, in this developing cartridge, rotation of the driving input gear is transmitted to the developing roller gear via a supply roller gear and an idle gear. In this configuration, the driving input gear and the idle gear are directly supported by a housing of the developing cartridge whereas the supply roller gear is fixed to an axis of a supply roller, and the axis of the supply roller is supported by a separate bearing which is fixed to the housing. 
       SUMMARY 
       [0005]    However, in the above-described technology, since the driving input gear and a driven gear (for example, the supply roller gear) which receives driving force from the driving input gear are supported by separate members, the distance between an axis of the driving input gear and an axis of the driven gear is less precise, whereby uneven rotation of the gears is caused. 
         [0006]    Therefore, a developing cartridge which is configured to position an axis of rotation of a developing roller and an axis of rotation of a gear for transmitting driving force to the developing roller more precisely would be helpful. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0007]      FIG. 1  is a diagram illustrating a schematic configuration of a laser printer which is provided with a developing cartridge according to an illustrative embodiment. 
           [0008]      FIG. 2  is a side view illustrating the developing cartridge according to an illustrative embodiment. 
           [0009]      FIG. 3  is an exploded perspective view illustrating a configuration of a left surface of the developing cartridge. 
           [0010]      FIGS. 4   a  and  4   b  provide diagrams illustrating a left surface of the developing cartridge.  FIG. 4   a  is a diagram illustrating a state in which a developing roller gear, a supply roller gear and a driving input gear are removed and  FIG. 4   b  is a diagram illustrating a state in which the developing roller gear, the supply roller gear and the driving input gear are attached. 
           [0011]      FIG. 5   a  is a sectional view of an area near a first bearing unit of  FIG. 4  and  FIG. 5   b  is a sectional view of an area near the driving input gear. 
           [0012]      FIG. 6   a  is a side view of the developing cartridge to which a gear cover is attached and  FIG. 6   b  is a plan view schematically illustrating a drum cartridge. 
           [0013]      FIG. 7  is a sectional view illustrating an area near a left end of the developing roller in a developing cartridge according to another illustrative embodiment. 
           [0014]      FIG. 8   a  is a diagram illustrating a case in which a driving input gear according to a second illustrative embodiment is directly supported by a receiving member and  FIG. 8   b  is a diagram illustrating a state in which a driving input gear according to a third illustrative embodiment is supported by a receiving member via a shaft. 
           [0015]      FIG. 9  is a diagram illustrating another illustrative embodiment of a receiving member and is a sectional view illustrating a claw of the receiving member. 
           [0016]      FIGS. 10   a  and  10   b  provide an illustrative modification with an intermediate gear which is meshed with a driving input gear and a developing roller gear.  FIG. 10   a  is a diagram illustrating a supply roller gear and the intermediate gear being meshed between the driving input gear and the developing roller gear, and  FIG. 10   b  is a diagram which illustrates the intermediate gear being meshed between the driving input gear and the developing roller gear. 
       
    
    
     DETAILED DESCRIPTION 
     Entire Configuration of Laser Printer 
       [0017]    Hereinafter, an illustrative embodiment will be described in detail with reference to the drawings. In the following description, a schematic configuration of an image forming apparatus such as a laser printer  1  provided with a developing cartridge  28  according to an illustrative embodiment will be described. 
         [0018]    As illustrated in  FIG. 1 , the laser printer  1  is provided with a feeder unit  4  which supplies a paper sheet  3  to an apparatus main body  2 , an image forming unit  5  which forms an image on the supplied paper sheet  3 , and the like. 
         [0019]    Note that, in the following description, directions are defined with reference to a user who is using the laser printer  1 . That is, in  FIG. 1 , the right side is defined as “front,” the left side is defined as “rear,” the near side is defined as “left” and the far side is defined as “right.” The up and down direction in  FIG. 1  is defined as “up and down.” 
         [0020]    The feeder unit  4  is mainly provided with a paper sheet feeding tray  6  which is attached to a bottom in the apparatus main body  2  in an attachable and detachable manner, and a paper sheet feeding mechanism  7  which conveys the paper sheet  3  from the paper sheet feeding tray  6  to the image forming unit  5 . In the feeder unit  4 , the paper sheet  3  in the paper sheet feeding tray  6  is fed one at a time by the paper sheet feeding mechanism  7  into the image forming unit  5 . 
         [0021]    The image forming unit  5  is provided with a scanner unit  16 , a process cartridge  17 , a fixing device  18  and the like. 
         [0022]    The scanner unit  16  is provided in an upper section in the apparatus main body  2 . In the scanner unit  16 , laser light in accordance with image data is transmitted via a polygon mirror  19 , lenses  20  and  21 , reflectors  22 ,  23  and  24 , and the like (see the dashed line) and illuminates a surface of the photosensitive drum  27  by high-speed scanning. 
         [0023]    The process cartridge  17  is configured to be attached to the apparatus main body  2  in an attachable and detachable manner. This process cartridge  17  includes a developing cartridge  28  and a drum cartridge  39 . 
         [0024]    The developing cartridge  28  is attachable to and detachable from the apparatus main body  2  in a state in which the developing cartridge  28  is attached to the drum cartridge  39 . Note that the developing cartridge  28  may be configured to be attachable to and detachable from the drum cartridge  39  which is fixed to the apparatus main body  2 . The developing cartridge  28  is provided with a housing  50 , a developing roller  31 , a thickness regulating blade  32  and a supply roller  33 . Toner is accommodated in the housing  50 . 
         [0025]    In this developing cartridge  28 , the developing roller  31  is supplied with toner accommodated in the housing  50  by the supply roller  33 . At this time, the developing cartridge  28  is positively electrified by friction, between the supply roller  33  and the developing roller  31 . The toner supplied on the developing roller  31  enters between the thickness regulating blade  32  and the developing roller  31  following rotation of the developing roller  31 , and is carried on the developing roller  31  as a thin layer of constant thickness while being electrified by friction. Note that a detailed configuration of the developing cartridge  28  will be described in detail below. 
         [0026]    The drum cartridge  39  is mainly provided with a photosensitive drum  27 , a scorotron charging unit  29  and a transfer roller  30 . In the drum cartridge  39 , the surface of the photosensitive drum  27  is uniformly and positively charged by the scorotron charging unit  29  and then is exposed by high-speed scanning of laser light from the scanner unit  16 . As a result, the potential of the exposed portion decreases and an electrostatic latent image according to the image data is formed. 
         [0027]    Subsequently, the developing roller  31  rotates in contact with the photosensitive drum  27 , whereby the electrostatic latent image formed on the surface of photosensitive drum  27  is supplied with the positively-charged toner carried on the surface of the developing roller  31  and a toner image is formed on the surface of the photosensitive drum  27 . Then, as the photosensitive drum rotates, the toner image on the photosensitive drum  27  is transferred to the paper sheet  3  by the transfer roller  30  while the paper sheet  3  is conveyed between the photosensitive drum  27  and the transfer roller  30 . 
         [0028]    The fixing device  18  is provided at the rear side of the process cartridge  17 , and is provided with a heat roller  41  and a pressure roller  42  which pressurizes the heat roller  41 . In the fixing device  18 , while the paper sheet  3  passes between the heat roller  41  and the pressure roller  42 , the toner transferred to the paper sheet  3  is heat fixed. The paper sheet  3  which has undergone heat fixing in the fixing device  18  is conveyed to a paper sheet output path  44  by a conveyance roller  43 . Then, the paper sheet  3  fed to the paper sheet output path  44  is output on the paper sheet output tray  46  by the output roller  45 . 
         [0029]    Detailed Configuration of Developing Cartridge 
         [0030]    Next, a detailed configuration of the developing cartridge  28  as a feature of the disclosure will be described. 
         [0031]    The developing cartridge  28  is provided with, as illustrated in  FIGS. 1 and 2 , the housing  50 , the developing roller  31 , the supply roller  33 , an agitator  34 , a gear train  60 , a receiving member  100  and a gear cover  70  which covers the gear train  60  (see  FIG. 6(   a )). 
         [0032]    As illustrated in  FIG. 2 , the developing roller  31  and the supply roller  33  are supported by the housing  50  via the receiving member  100  which will be described below. The housing  50  is made of resin, such as polystyrene. The housing  50  includes a left wall  52  which has an opening  53  at a rear wall  51  side (one side) (see also  FIG. 3 ). The gear train  60  and the receiving member  100  are disposed on the left wall  52 . In  FIG. 2  and other drawings, the tooth profile of each gear which constitutes the gear train  60  is omitted. 
         [0033]    The gear train  60  is a mechanism which applies driving force input from outside to the developing roller  31 , the supply roller  33  and the agitator  34 . In particular, the gear train  60  in which driving force is input from outside includes the driving input gear  61 , a developing roller gear  62  which rotates integrally with the developing roller  31 , a supply roller gear  63  which rotates integrally with the supply roller  33 , an agitator gear  65  which rotates integrally with the agitator  34  and an idle gear  64  which is meshed with the driving input gear  61  and with the agitator gear  65 . 
         [0034]    As illustrated in  FIG. 2 , the driving input gear  61  is directly meshed with the developing roller gear  62  and the supply roller gear  63 . The driving input gear  61 , the developing roller gear  62  and the supply roller gear  63  are rotatably supported by the receiving member  100 . 
         [0035]    As illustrated in  FIG. 3 , in the driving input gear  61 , an engaging unit, for example, a recess  61 A is formed on an outer surface of the developing roller  31  in an axial direction (hereinafter, simply referred to as “axial direction”). This recess  61 A is engageable with and disengageable from a driving source M in the axial direction (see  FIG. 4(   b )). 
         [0036]    The receiving member  100  is disposed between the housing  50  and the developing roller gear  62 , and between the housing  50  and the driving input gear  61 . The receiving member  100  mainly includes a plate-shaped receiving member main body  101 , a driving input gear support unit  110 , a first bearing unit  120  used as a bearing of the developing roller  31 , a second bearing unit  130  used as a bearing of the supply roller  33 , a first engaged unit such as a pair of first engaging holes  140 , a second engaged unit such as a second engaging hole  150 , and two claws  160  (see also  FIG. 5(   a )). Note that the receiving member is made of a material which is harder than a material of the housing  50 , e.g., polyacetal, from the viewpoint of wear resistance. 
         [0037]    The driving input gear support unit  110  in this illustrative embodiment is a boss which has a cylindrical shape and protrudes in an axial direction of the developing roller  31  away from the receiving member main body  101 . As illustrated in  FIG. 5(   b ), this driving input gear support unit  110  supports the driving input gear  61  directly and rotatably by engaging a recess  61 B formed on a surface which faces the receiving member  100  of the driving input gear  61 . The driving input gear support unit  110  is sized to have a length that extends to gear teeth  61 C of the driving input gear  61  in the axial direction to prevent misalignment of the position of the gear teeth  61 C of the driving input gear  61 . 
         [0038]    As illustrated in  FIG. 3  a first bearing unit  120  is formed to penetrate the receiving member main body  101  in the axial direction at the rear side of the driving input gear support unit  110 , and has a cylindrical shape protruding toward the interior of the receiving member main body  101  in the axial direction. 
         [0039]    As illustrated in  FIG. 3 , a second bearing unit  130  is formed to penetrate driving input gear support unit  110  in the axial direction below the driving input gear support unit  110 , and has a cylindrical shape projecting toward the interior of the receiving member main body  101  in the axial direction. 
         [0040]    First engaging holes  140  are a pair of holes penetrating driving input gear support unit  110  in the axial direction disposed at upper and lower sides of the first bearing unit  120 , which sandwich the first bearing unit  120 . 
         [0041]    The second engaging hole  150  is a hole formed inside the driving input gear support unit  110  when seen in an axial direction. In particular, the second engaging hole  150  has a shape in which a part of a circle is narrowed, as illustrated in  FIG. 2 . Edges  151  which face each other at the narrowed portion extend in the direction parallel to the direction toward the center of an axis  31 A of the developing roller  31  from the center of a second projection  56  which will be described below. 
         [0042]    As illustrated in  FIG. 5(   a ), two claws  160  are formed at an upper end and a lower end of the receiving member main body  101  to sandwich the first bearing unit  120  from upper and lower sides. The claws  160  extend from the receiving member main body  101  inwardly in the axial direction and have a hook shape projecting outward at ends thereof. The claws  160  have flexibility by extending in an elongated manner from the receiving member main body  101 . 
         [0043]    The receiving member main body  101  includes a positioning unit  170  projecting downward as illustrated in  FIG. 3 ; and a rib  171  extending in a substantially up and down direction and formed in an axial direction on an outer surface of the positioning unit  170 . 
         [0044]    Next, a configuration of the housing  50  to which the receiving member  100  above is attached will be described. 
         [0045]    The housing  50  includes, at the rear side of the left wall  52 , a first opening  53 , a second opening  54 , a first engaging unit, which in this illustrative embodiment is a pair of first projections  55 , a second engaging unit, which in this illustrative embodiment is second projection  56 , and two locking holes  57 . 
         [0046]    The first opening  53  is formed in a substantially C-shape which opens on the side of the rear wall  51  when viewed from a side. The axis  31 A of the developing roller  31  is disposed in the first opening  53 . 
         [0047]    The second opening  54  is formed at a diagonally lower front of the first opening  53 . An axis  33 A of the supply roller  33  is disposed in the second opening  54 . 
         [0048]    The first projections  55  are formed to project in an axial direction from the left wall  52 , i.e., toward the receiving member  100 , at positions to face each other via the first opening  53  in the direction which intersects perpendicularly to an axial direction corresponding to a pair of first engaging holes  140 . 
         [0049]    In the front of the first opening  53 , the second projection  56  is formed to project toward the receiving member  100  from the left wall  52  corresponding to the second engaging hole  150 . A diameter of the second projection  56  is substantially the same as the distance between edges  151  of the second engaging hole  150 . 
         [0050]    Two locking holes  57  are formed at positions to face each other via the first opening  53 , and are formed in the housing  50  in an axial direction as illustrated in  FIG. 5(   a ). 
         [0051]    The left wall  52  of the housing  50  includes an extending portion  58  disposed below the second opening  54 . The extending portion  58  extends downward as a plate as illustrated in  FIG. 3 . 
         [0052]    The receiving member  100  is fixed to the housing  50  by the claws  160  engaging the locking holes  57  as illustrated in  FIG. 5(   a ). In particular, the claws  160  penetrate the locking holes  57  from outside to inside, and are locked by the edges of the locking hole  57  inside the left wall  52 . 
         [0053]    In the first bearing unit  120 , a portion protruding from the receiving member main body  101  in an axial direction inside fits in the first opening  53 . The first bearing unit  120  supports the axis  31 A of the developing roller  31  directly and rotatably. As illustrated in  FIG. 4(   a ), the second bearing unit  130  supports the axis  33 A of the supply roller  33  directly and rotatably. 
         [0054]    The pair of first projections  55  of the housing  50  fits in a pair of first engaging holes  140  of the receiving member  100 . The second projection  56  of the housing  50  fits in the second engaging hole  150  of the receiving member  100 . 
         [0055]    As illustrated in  FIG. 4(   b ), with respect to the housing  50  to which the receiving member  100  is attached, the developing roller gear  62  is fixed to a left end of the axis  31 A of the developing roller  31 , and is rotatably supported by the receiving member  100  via the axis  31 A of the developing roller  31 . The supply roller gear  63  is fixed to a left end of the axis  33 A of the supply roller  33 , and is rotatably supported by the receiving member  100  via the axis  33 A of the supply roller  33 . 
         [0056]    The extending portion  58  of the housing  50  overlaps the positioning unit  170  of the receiving member  100  and reinforces the positioning unit  170 . 
         [0057]    As illustrated in  FIG. 6(   a ), the gear cover  70  is a member which covers the gear train  60  and is fixed to the left wall  52  with screws. The gear cover  70  is formed not to overlap the positioning unit  170  of the receiving member  100  when seen in an axial direction. That is, the positioning unit  170  extends outward from below the gear cover  70 . 
         [0058]    On the other hand, a case body  80  of the drum cartridge  39  to which the developing cartridge  28  is attached includes a groove  81  on the left side of a bottom surface. When the developing cartridge  28  is attached to the drum cartridge  39 , the positioning unit  170  is disposed in the groove  81 . An urging member (not shown) which urges the developing cartridge  28  to the left is provided in the apparatus main body  2  such that the rib  171  of the positioning unit  170  is in contact with the wall which constitutes the groove  81 . An urging member such as an electrode makes contact with a right end of the axis  31 A of the developing roller  31  and supplies the developing roller  31  with development bias. 
         [0059]    Operations and effects of the developing cartridge  28  configured as described above will be described. 
         [0060]    When the driving source M engages the recess  61 A of the driving input gear  61  and driving force is applied to the driving input gear  61 , the driving input gear  61  is rotated clockwise in  FIG. 2 . Since the developing roller gear  62  is meshed with the driving input gear  61 , driving force is input therein from the driving input gear  61  and the developing roller gear  62  is rotated counterclockwise in  FIG. 2 . As such, the developing roller  31  is rotated. Since the supply roller gear  63  is meshed with the driving input gear  61 , driving force is input therein from the driving input gear  61  and the supply roller gear  63  is rotated counterclockwise in  FIG. 2 . As such, the supply roller  33  is rotated. Since the idle gear  64  is meshed with the driving input gear  61 , the idle gear  64  is rotated counterclockwise in  FIG. 2 . As such, the agitator gear  65  which is meshed with the idle gear  64  is rotated clockwise in  FIG. 2 . 
         [0061]    Now, unless the distance between axes of gears, such as the developing roller gear  62  and the driving input gear  61  which are meshed with each other, is not determined precisely, uneven rotation of the gears may be caused. 
         [0062]    Then, according to this illustrative embodiment, since the developing roller gear  62  and the driving input gear  61  are rotatably supported by the receiving member  100 , the distance between the axis of the developing roller gear  62  and the axis of the driving input gear  61  can be determined precisely using a single member between the housing  50  and the developing roller gear  62 , and between the housing and the driving input gear  61 . 
         [0063]    Since the supply roller gear  63  is rotatably supported by the receiving member  100 , the distance between an axis of the supply roller gear  63  and the axis of the driving input gear  61  can also be determined precisely by the receiving member  100 . 
         [0064]    In the receiving member  100 , since the driving input gear support unit  110  which rotatably supports the driving input gear  61  is formed as a boss in which the driving input gear  61  fits, space on an inner side of the gear teeth of the driving input gear  61  when seen in an axial view can be used effectively, as compared with a configuration in which the driving input gear  61  includes an axis which projects on the side of the receiving member  100  and is rotatably supported by the receiving member  100 . As such, the size of the developing cartridge  28  can be reduced. 
         [0065]    Since the driving input gear support unit  110  extends to the gear teeth of the driving input gear  61  in an axial direction, misalignment of the positions of the gear teeth of the driving input gear  61  can be prevented. 
         [0066]    Even in a situation in which the first opening  53  is easily opened when the developing roller gear  62  receives driving force from the driving input gear  61 , since the pair of first engaging holes  140  of the receiving member  100  engages the pair of first projections  55  which face each other via the first opening  53 , the first opening  53  which opens on the side of the rear wall  51  may be prevented from being opened. 
         [0067]    Since the second projection  56  fits in the second engaging hole  150 , even if the receiving member  100  is to be rotated about the developing roller  31  when the developing roller  31  is rotated, the edges  151  of the second engaging holes  150  abut the second projection  56 . As such, rotation of the receiving member  100  can be prevented. 
         [0068]    since the second projection  56  and the second engaging hole  150  are provided inside the driving input gear support unit  110  when seen in an axial direction, as compared with a case in which the second projection  56  and the second engaging holes  150  are disposed outside the driving input gear support unit  110 , the size of the developing cartridge  28  can be reduced. 
         [0069]    Since the portion projecting in an axial direction inside the first bearing unit  120  which is the bearing of the developing roller  31  fits in the first opening  53 , the developing roller  31  can be positioned with respect to the housing  50 . 
         [0070]    Since the positioning unit  170  of the receiving member  100  is in contact with the groove  81  of the drum cartridge  39 , the developing cartridge  28  can be positioned with respect to the drum cartridge  39  by the receiving member  100 . 
         [0071]    A hard material may be used as a member which supports the developing roller  31  and the gear train  60  to reduce wear resistance. The amount of the hard material can be reduced by forming the receiving member  100  with a material harder than the material of the housing  50 , which also can reduce cost. 
         [0072]    Although an illustrative embodiment has been described, the disclosure is not limited to the same. The specific configuration may be changed suitably without departing from the scope of the disclosure. 
         [0073]    In the above-described illustrative embodiment, although the developing roller gear  62  is rotatably supported by the receiving member  100  via the axis  31 A of the developing roller  31 , the disclosure is not limited to the same. For example, as illustrated in  FIG. 7 , a developing roller gear  66  may be supported directly and rotatably by the receiving member  100 . 
         [0074]    In particular, the developing roller gear  66  includes a gear unit  66 A which is provided with gear teeth on an outer peripheral surface, and a portion to be supported  66 B extending in an axial direction inside, i.e., toward the receiving member  100 , from the gear unit  66 A. The portion to be supported  66 B is disposed in the first bearing unit  120  of the receiving member  100 , and is supported by the receiving member  100  directly and rotatably. 
         [0075]    Although the driving input gear  61  is supported by the receiving member  100  by the boss-shaped driving input gear support unit  110  which projects in an axial direction outside the receiving member  100  engaging the recess  61 B formed in the driving input gear  61  in the above-described illustrative embodiment, the disclosure is not limited to this. For example, as illustrated in  FIG. 8(   a ), the driving input gear  67  may include an integral axis  67 A extending in an axial direction inside from the gear unit  67 B, and may be supported by the driving input gear support unit  180  by the axis  67 A being engaged with the driving input gear support unit  180  which is formed in the receiving member  100 . 
         [0076]    In the above-described illustrative embodiment, although the driving input gear  61  is directly supported by the receiving member  100 , the disclosure is not limited to the same. For example, as illustrated in  FIG. 8(   b ), the driving input gear  68  may be supported by the receiving member  100  via the shaft  200 . In particular, the driving input gear  68  is fixed to the shaft  200  and is rotated integrally with the shaft  200 . And the driving input gear support unit  180  is formed in the receiving member  100 . The shaft  200  is rotatably supported by this driving input gear support unit  180 . 
         [0077]    Thus, in a case in which the driving input gear  61  is supported by the receiving member  100  via the shaft  200 , the distance between an axis of the driving input gear  61  and an axis of the developing roller gear  62  can be determined precisely. 
         [0078]    Although in the above-described illustrative embodiment the first engaging hole  140  is molded separately from the claw  160 , a hole formed at the time of molding the claw  160  may serve as the first unit to be engaged. For example, as illustrated in  FIG. 9 , a hole  340  formed at the base portion of the claw  360  for molding the claw  360  is formed in the receiving member  300 . This hole  340  is the first unit to be engaged which engages the first projection  55  formed in the housing  50 . According to this example, a simple molding die can be used and the size of the developing cartridge  28  can be reduced. 
         [0079]    In the above-described illustrative embodiment, although the driving input gear  61  is meshed with the developing roller gear  62 , the disclosure is not so limited. For example, driving force of the driving input gear  61  may be applied to the developing roller gear  62  by at least one intermediate gear which is rotatably supported by the receiving member  100  and is meshed with the developing roller gear  62  and with the driving input gear  61 . 
         [0080]    In particular, an example of such a form will be described. As illustrated in  FIG. 10(   a ), the supply roller gear  63  and the intermediate gear  69  are rotatably supported by the receiving member  100  between the developing roller gear  62  and the driving input gear  61 . The supply roller gear  63  is meshed with the driving input gear  61 . The intermediate gear  69  is meshed with the supply roller gear  63  and with the developing roller gear  62 . 
         [0081]    With the configuration described above, the distance between the axis of the driving input gear  61  and an axis of the supply roller gear  63 , the distance between the axis of the supply roller gear  63  and an axis of the intermediate gear  69 , and the distance between the axis of the intermediate gear  69  and the axis of the developing roller gear  62  can be determined precisely. 
         [0082]    As another modification, driving force of the driving input gear  61  may be applied to the developing roller gear  62  by the intermediate gear  69  which is meshed with the driving input gear  61 , the developing roller gear  62  and the supply roller gear  63 , and is rotatably supported by the receiving member  100  as illustrated in  FIG. 10(   b ). 
         [0083]    Although the driving input gear support unit  110  is formed to have a length that extends to the gear teeth  61 C of the driving input gear  61  in an axial direction in the above-described illustrative embodiment, the driving input gear support unit  110  may be formed to extend across the entire range of the gear teeth  61 C in an axial direction. 
         [0084]    Although the first engaging unit is a projection and the first engaged unit is a hole in the above-described illustrative embodiment, the disclosure is not so limited. The first engaging unit may be a hole and the first engaged unit may be a projection. As another modification, the first engaging unit may include a hole and a projection. In this modification, the first engaged unit may then include a projection corresponding to the hole of the first engaging unit and a hole corresponding to the projection of the first engaging unit. 
         [0085]    Although the second projection  56  and the second engaging hole  150  are provided inside the driving input gear support unit  110  when seen in an axial direction in the above-described illustrative embodiment, the disclosure is not so limited. The second projection  56  and the second engaging hole  150  may be provided outside the driving input gear support unit  110  in an axial direction. 
         [0086]    Although the drum cartridge  39  has been described as the device to which the developing cartridge  28  is attached in the above-described illustrative embodiment, the disclosure is not limited to the same. For example, the device to which the developing cartridge  28  is attached may be the laser printer  1 . 
         [0087]    Although the disclosure is applied to the laser printer  1  in the above-described illustrative embodiment, the disclosure is not limited to the same. The disclosure may also be applied to other image forming apparatuses, such as a copying device and a multi-function device.