Abstract:
A cartridge assembly detachably mounted on a main casing of an image forming device includes a first cartridge, a second cartridge, and a lock member. The first cartridge has a first handle. The second cartridge has a second handle. The first handle and the second handle are configured to provide a relative position capable of realizing simultaneous access to the first handle and the second handle in case of an assembled state between the second cartridge and the first cartridge for integral attachment to or detachment from the main casing. The lock member has a lock section and an operation section. The lock section is movable between a lock position and an unlock position. The operation section is configured to move the lock section between the lock position and the unlock position. The first handle and the operation section are configured to provide a relative position capable of realizing simultaneous access to the first handle and the operation section to move the lock section from the lock position to the unlock position for detachment of the second cartridge from the first cartridge.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority from Japanese Patent Application No. 2009-130902 filed May 29, 2009. The entire content of the priority application is incorporated herein by reference. 
       TECHNICAL FIELD 
       [0002]    The present invention relates to a cartridge assembly including a plurality of cartridges assembled to each other, such as a process unit (process cartridge) and a developing unit constituting a part of an image forming device. 
       BACKGROUND 
       [0003]    In a conventional image forming device, such as a laser printer, a process cartridge (process unit) is detachably mounted to a main casing. The process cartridge includes, for example, a drum cartridge and a developing cartridge. The drum cartridge includes a photosensitive drum. The developing cartridge is detachably mounted to the drum cartridge and includes a developing roller that supplies toner to a surface of the photosensitive drum. 
         [0004]    In the image forming device provided with the process cartridge, the drum cartridge and the developing cartridge can be integrally detached from and attached to the main casing as an integral process cartridge. Further, only the developing cartridge can be detached from and attached to the main casing with separating the developing cartridge from the drum cartridge, while maintaining the drum cartridge in the main casing. 
         [0005]    Further, such a conventional process cartridge is provided with a lock lever. The lock lever prohibits separation of the developing cartridge from the drum cartridge in order to prevent undesired separation. The lock lever is disposed at one widthwise end portion of the drum cartridge. When the developing cartridge is assembled to the drum cartridge, a lower end portion of the lock lever is engaged with a predetermined portion of the developing cartridge from above. When an upper end portion of the lock lever is pressed down, the lower end portion is disengaged from the predetermined portion. Accordingly, the developing cartridge can be separated from the drum cartridge. 
       SUMMARY 
       [0006]    Such a lock lever can prevent the developing cartridge from accidentally falling off the drum cartridge while the process cartridge is removed from the main casing. However, in order to separate the developing cartridge from the drum cartridge, a user needs to press down the upper end portion of the lock lever by one hand while holding the developing cartridge by another hand. In other words, the developing cartridge cannot be separated from the drum cartridge with only one hand. Hence, separation of the developing cartridge from the drum cartridge needs troublesome labor and is not user-friendly. 
         [0007]    Incidentally, the developing unit is another example of the cartridge assembly. The developing unit includes a roller cartridge and a toner cartridge assembled thereto. The roller cartridge accommodates therein a developing roller and a toner supply roller, and the toner cartridge accommodates therein a toner to be supplied to the roller cartridge. Therefore, in case of the developing unit, easy separation of the toner cartridge from the roller cartridge is required. 
         [0008]    In view of the foregoing, it is an object of the present invention to provide a cartridge assembly such as a process cartridge and a developing unit of an image forming device with enhanced operability at the time of separation of a second cartridge (such as the developing cartridge and the toner cartridge) from a first cartridge (such as the drum cartridge and the roller cartridge) as well as with enhanced prevention of the second cartridge from undesired separation from the first cartridge. 
         [0009]    In order to attain the above and other objects, the present invention provides a cartridge assembly detachably mounted on a main casing of an image forming device including a first cartridge, a second cartridge, and a lock member. The first cartridge has a first handle. The second cartridge is detachably mounted on the first cartridge and has a second handle. The first handle and the second handle are configured to provide a relative position capable of realizing simultaneous access to the first handle and the second handle in case of an assembled state between the second cartridge and the first cartridge for integral attachment to or detachment from the main casing. The lock member has a lock section and an operation section. The lock section is movable between a lock position to prohibit separation of the second cartridge from the first cartridge and an unlock position to permit separation of the second cartridge from the first cartridge. The lock section is maintained in the lock position in the assembled state of the second cartridge to the first cartridge. The operation section is configured to move the lock section between the lock position and the unlock position. The first handle and the operation section are configured to provide a relative position capable of realizing simultaneous access to the first handle and the operation section to move the lock section from the lock position to the unlock position for detachment of the second cartridge from the first cartridge. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The particular features and advantages of the present invention as well as other objects will become apparent from the following description taken in connection with the accompanying drawings, in which: 
           [0011]      FIG. 1  is a side cross-sectional view of a printer according to one embodiment of the present invention; 
           [0012]      FIG. 2  is a cross-sectional view of a process cartridge employed in the printer shown in  FIG. 1 ; 
           [0013]      FIG. 3  is a cross-sectional view of a drum cartridge employed in the process cartridge shown in  FIG. 2 ; 
           [0014]      FIG. 4  is a perspective view of a developing cartridge employed in the process cartridge shown in  FIG. 2  as viewed from a left front side; 
           [0015]      FIG. 5  is a side cross-sectional view of the developing cartridge employed in the process cartridge shown in  FIG. 2 ; 
           [0016]      FIG. 6  is a perspective view of a lock member employed in the developing cartridge shown in  FIG. 4 ; 
           [0017]      FIG. 7  is a side cross-sectional view of the process cartridge when the developing cartridge is just about to be detached from or attached to the drum cartridge; 
           [0018]      FIG. 8  is a side cross-sectional view of the process cartridge while the developing cartridge is being detached from or attached to the drum cartridge immediately after (for detachment) or before (for attachment) a state shown in  FIG. 7 ; 
           [0019]      FIG. 9  is a side cross-sectional view of the process cartridge while the developing cartridge is being detached from or attached to the drum cartridge immediately after or before a state shown in  FIG. 8 ; and 
           [0020]      FIG. 10  is a side cross-sectional view of the process cartridge when the developing cartridge has been detached from the drum cartridge immediately after or before a state shown in  FIG. 9 . 
           [0021]      FIG. 11  is a schematic view of a roller cartridge and a toner cartridge assembled to a developing unit. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    Next, a printer as an image forming device according to one embodiment of the present invention will be described with reference to  FIGS. 1 through 10 . 
         [0023]    1. Overall Structure of Printer 
         [0024]    The printer  1  includes a main casing  2 . Within the main casing  2 , a process cartridge  3 , an exposure unit  4 , a sheet supply cassette  11 , a fixing unit  13 , and a discharge tray  14  are provided. The process cartridge  3  is disposed at a central part of the main casing  2 . The exposure unit  4  is disposed above the process cartridge  3  and provided with a laser emission unit. 
         [0025]    The main casing  2  has a front opening at which a front door  5  is provided. The front door  5  is pivotally movable between an open position and a closed position about a lower end portion thereof. When the front door  5  is pivotally moved to the open position, the process cartridge  3  is exposed to an atmosphere. The process cartridge  3  is detachable from and attachable to the main casing  2  through the front opening. 
         [0026]    The process cartridge  3  includes a drum cartridge  8  and a developing cartridge  10 . The drum cartridge  8  includes a photosensitive drum  6  and a scorotron charger  7 . The developing cartridge  10  includes a developing roller  9  and a toner supply roller  19 . The developing cartridge  10  is detachably assembled to the drum cartridge  8  so that a part of a circumferential surface of the developing roller  9  is brought into contact with a circumferential surface of the photosensitive drum  6 . 
         [0027]    In association with rotation of the photosensitive drum  6 , the surface of the photosensitive drum  6  is uniformly charged by the scorotron charger  7 . The photosensitive drum  6  is then selectively exposed by a laser beam emitted from the exposure unit  4 , so that an electrostatic latent image based on image data is formed on the surface of the photosensitive drum  6 . When the electrostatic latent image opposes the developing roller  9 , electric potential difference between the electrostatic latent image and the developing roller  9  supplies toner to the electrostatic latent image from the developing roller  9 . Therefore, a visible toner image corresponding to the electrostatic latent image can be formed on the surface of the photosensitive drum  6 . 
         [0028]    The sheet supply cassette  11  is provided in a lower section of the main casing  2 . The sheet supply cassette  11  accommodates a sheet P therein. Each sheet P is conveyed from the sheet supply cassette  11 , and passes between the photosensitive drum  6  and a transfer roller  12  disposed opposite to the photosensitive drum  6 . Upon facing the transfer roller  12 , the toner image formed on the surface of the photosensitive drum  6  is transferred onto the sheet P passing between the photosensitive drum  6  and the transfer roller  12 . The transfer roller  12  is retained in the drum cartridge  8 . 
         [0029]    The fixing unit  13  is provided at a position downstream of the process cartridge  3  in a conveying direction of the sheet P. The sheet P onto which the toner image was transferred is conveyed to the fixing unit  13 . In the fixing unit  13 , the toner image is fixed on the sheet P by heat and pressure. The discharge tray  14  is provided in a top surface of the main casing  2 . The sheet P on which an image has been fixed is discharged to the discharge tray  14  by various rollers. 
         [0030]    Note that, throughout the specification, the terms “above”, “below”, “right”, “left”, “front”, “rear” and the like will be used assuming that the printer  1  is disposed in an orientation in which it is intended to be used. More specifically, in  FIG. 1 , a left side and a right side are a rear side and a front side, respectively. 
         [0031]    2. Process Cartridge 
         [0032]    As described above, the process cartridge  3  includes the drum cartridge  8  and the developing cartridge  10 . 
         [0033]    2-1. Drum Cartridge 
         [0034]    As shown in  FIG. 3 , the drum cartridge  8  is integrally provided with a bottom wall  31 , a rear wall  32 , a top wall  33 , a front wall  34 , and right and left side walls  35 . The bottom wall  31  is provided with a transfer roller retaining section  36 , a developing cartridge mounting section  37 , a roller support section  38 , and an extending section  39  successively in this order from a rear side of the bottom wall  31  to a front side thereof. 
         [0035]    The transfer roller retaining section  36  is generally U-shaped in cross-section, and the U-shape has a top opening. The transfer roller retaining section  36  retains the transfer roller  12  therein. The transfer roller  12  has a rotation shaft, and each end portion of the rotation shaft is rotatably supported to the side wall  35 . 
         [0036]    The transfer roller retaining section  36  has a front edge from which the developing cartridge mounting section  37  extends frontward. The developing cartridge mounting section  37  is formed in a plate-shape, and formed with an elongated opening  40  extending in a right-to-left direction (hereinafter referred to as “widthwise direction”). The opening  40  is provided at a position in a substantially middle part of the developing cartridge mounting section  37  in the frontward/rearward direction. The opening  40  has a width greater than that of the sheet P (shown in  FIG. 1 ) and is open frontward. The sheet P is conveyed into the drum cartridge  8  through the opening  40 , and passes between the photosensitive drum  6  and the transfer roller  12 . 
         [0037]    The roller support section  38  is generally U-shaped in cross-section, and the U-shape has a bottom opening. The roller support section  38  supports a roller  41 . The roller  41  has a rotational shaft, and each end portion of the rotational shaft is rotatably supported to the side wall  35 . As shown in  FIG. 1 , when the process cartridge  3  is assembled to the main casing  2 , the roller  41  is in confrontation with a roller  42  provided at the main casing  2 . The roller  41  and the roller  42  constitute a registration roller for adjusting a conveying timing of the sheet P. 
         [0038]    The roller support section  38  has a front edge from which the extending section  39  extends diagonally above and frontward. The extending section  39  is formed in a generally plate-shape. The extending section  39  is provided with an engaged member  43  upstanding therefrom. The engaged member  43  has a U-shape as viewed from the front side (see  FIG. 4 ), and the U-shape has a bottom opening. 
         [0039]    The transfer roller retaining section  36  has a lower portion from which the rear wall  32  extends diagonally above and rearward. The rear wall  32  is bent in its middle section so as to extend upward vertically from the middle section. The rear wall  32  has a front surface provided with a cleaning brush  44 . The cleaning brush  44  is employed to remove paper-dust deposited on the photosensitive drum  6 . Further, the rear wall  32  is formed with an elongated opening  45  extending in the widthwise direction and disposed below the cleaning brush  44 . After the sheet P has passed between the photosensitive drum  6  and the transfer roller  12 , the sheet P is conveyed toward the fixing unit  13  (shown in  FIG. 1 ) through the opening  45 . 
         [0040]    The rear wall  32  has an upper edge from which the top wall  33  extends frontward. The top wall  33  is in confrontation with the transfer roller retaining section  36  in an upper-to-lower direction. The top wall  33  has a rear end portion that is inclined upward toward the front side. Below the rear end portion of the top wall  33 , the scorotron charger  7  is disposed. 
         [0041]    The extending section  39  has a front edge from which the front wall  34  extends upward. The front wall  34  is formed in a generally plate-shape. The front wall  34  has an upper edge whose middle portion in the widthwise direction is integral with a first handle  46 . The first handle  46  is plate-shaped and extends frontward from the upper edge of the front wall  34 . 
         [0042]    The right and left side walls  35  are formed in substantially the same shape. Each of the side walls  35  is integrally provided with a drum retaining section  47  and a developing cartridge facing section  48 . A pair of the drum retaining sections  47  is adapted to close a space defined by the transfer roller retaining section  36 , the rear wall  32 , and the top wall  33  in the widthwise direction. Each end portion of the photosensitive drum  6  is rotatably supported to the drum retaining section  47 . 
         [0043]    Each of the developing cartridge facing sections  48  is in confrontation with the developing cartridge  10  when the developing cartridge  10  is mounted on the developing cartridge mounting section  37  of the bottom wall  31 . 
         [0044]    The drum retaining section  47  has a front edge, and the developing cartridge facing section  48  extends frontward from a lower half portion of the front edge. The developing cartridge facing section  48  has a lower edge that is connected to each widthwise edge of the developing cartridge mounting section  37 , the roller support section  38 , and the extending section  39 . The developing cartridge facing section  48  has a front edge that is connected to a widthwise edge of the front wall  34 . 
         [0045]    The developing cartridge facing section  48  has an upper edge  49 . A rear half portion of the upper edge  49  extends diagonally downward from the front side to the rear side. The upper edge  49  serves as a guide for guiding the developing cartridge  10  when the developing cartridge  10  is detached from or attached to the drum cartridge  8 . 
         [0046]    The drum retaining section  47  has a front end portion formed with a shaft receiving portion  50 . The shaft receiving portion  50  is a substantially rectangular-shaped notch open frontward. The notch is connected to the upper edge portion  49 . When the developing cartridge  10  is assembled to the drum cartridge  8 , the shaft receiving portion  50  receives a collar member  61  (described later) of the developing cartridge  10 . 
         [0047]    2-2. Developing Cartridge 
         [0048]    As shown in  FIGS. 4 and 5 , the developing cartridge  10  includes a box-shaped developing casing  51 . The developing casing  51  is integrally provided with a bottom wall  52 , a top wall  53 , right and left side walls  54 , and an extending section  55 . 
         [0049]    The bottom wall  52  includes a front bottom wall  56  and a rear bottom wall  57 . The front bottom wall  56  is formed in an arcuate shape in cross-section. The front bottom wall  56  has a rear edge from which the rear bottom wall  57  extends diagonally downward toward the rear side. 
         [0050]    The front bottom wall  56  has an upper edge  56 A from which the top wall  53  extends rearward. The top wall  53  is formed in a plate-shape. 
         [0051]    The right and left side walls  54  are formed in substantially the same shape. Each of the side walls  54  defines a space in cooperation with the bottom wall  52  and the top wall  53 . Accordingly, the developing casing  51  is formed with the space having a rear opening defined by the bottom wall  52 , the top wall  53  and the side walls  54 . 
         [0052]    Further, the space above the front bottom wall  56  is occupied by a toner chamber  58  accommodating toner therein. The space above the rear bottom wall  57  is occupied by a developing chamber  59  in which the developing roller  9  and the toner supply roller  19  are retained. The developing roller  9  has a rotation shaft  60 , and each end portion of the rotation shaft  60  rotatably extends through the side wall  54 . Each side wall  54  is provided with the collar member  61  having substantially cylindrical shape to cover a portion of the rotation shaft  60 , the portion being outwardly protruding from the side wall  54 . 
         [0053]    The extending section  55  is integrally provided with a horizontal extending section  62  and a vertical extending section  63 . The horizontal extending section  62  extends frontward from a front edge of the top wall  53  along an upper edge of the side wall  54 . The horizontal extending section  62  has a front edge from which the vertical extending section  63  extends along a front edge of the side wall  54 . 
         [0054]    Further, the extending section  55  is provided with a pair of arms  64  extending diagonally upward and frontward from a front surface of the vertical extending section  63 . The pair of the arms  64  is arranged spaced apart from each other in the widthwise direction. Each of the arms  64  has an upper edge, and a plate shaped second handle  65  is bridged between the upper edges of the arms  64 . As shown in  FIG. 2 , when the developing cartridge  10  is mounted on the drum cartridge  8 , a front end portion of the second handle  65  is disposed above the first handle  46 . The second handle  65  is arranged in confrontation with the first handle  46  and spaced apart from the same. 
         [0055]    A lock member  66  is disposed below the front end portion of the second handle  65 . As shown hi  FIG. 6 , the lock member  66  is integrally provided with a pivot shaft  67 , a first planar section  68 , a hook  69 , a second planar section  70 , and an operation section  71 . 
         [0056]    The pivot shaft  67  extends in the widthwise direction. The first planar section  68  extends downward from the pivot shaft  67 . The hook  69  extends downward from a widthwise center portion of a lower end portion of the first planar section  68  and has a free end bent rearward. The second planar section  70  extends frontward from the pivot shaft  67  so as to be perpendicular to the first planar section  68 . The second planar section  70  has a front edge from which the operation section  71  extends diagonally upward. 
         [0057]    Each end portion of the pivot shaft  67  protrudes from the first planar section  68  and the second planar section  70  in the widthwise direction. As shown in  FIG. 4 , a lower surface of the second handle  65  is provided with a pair of shaft support portions  72  spaced apart from each other in the widthwise direction. Each of the shaft support portions  72  is formed with a hole allowing each end portion of the pivot shaft  67  to rotatably extend therethrough in the widthwise direction. Since the end portions of the pivot shaft  67  rotatably extend through the holes of the shaft support portions  72 , the lock member  66  is pivotally movable about an axis of the pivot shaft  67 . The hook  69  is engageable with the engaged member  43  of the drum cartridge  8 . 
         [0058]    Further, at least one of the end portions of the pivot shaft  67  is provided with a torsion spring  73  at an inner side relative to the shaft support portion  72  in the widthwise direction. The torsion spring  73  has one end fixed to or seated on the second handle  65  and another end fixed to or seated on the first planar section  68 . Accordingly, the lock member  66  is constantly biased by the torsion spring  73  in a direction such that the hook  69  is moved rearward (the operation section  71  is moved downward). 
         [0059]    2-3. Separation of Developing Cartridge from Drum Cartridge 
         [0060]    As shown in  FIG. 2 , when the developing cartridge  10  is mounted in the drum cartridge  8 , the lock member  66  is disposed at a lock position by a biasing force of the coil spring  73 . That is, the hook  69  of the lock member  66  is engaged with the engaged member  43  from the front side, so that separation between the drum cartridge  8  and the developing cartridge  10  is prohibited. Further, the operation section  71  of the lock member  66  is disposed above the first handle  46  and below the second handle  65 . 
         [0061]    When the developing cartridge  10  is separated from the drum cartridge  8 , as shown in  FIG. 7 , the second handle  65  and the operation section  71  of the lock member  66  are collectively held by a single hand H of the user. Then, the operation section  71  is operated so as to be moved closer to the second handle  65 . The lock member  66  is thereby moved to an unlock position from the lock position. That is, engagement of the hook  69  relative to the engaged member  43  is released. Thus, separation of the developing cartridge  10  from the drum cartridge  8  is permitted. 
         [0062]    Next, as shown in  FIG. 8 , the second handle  65  is lifted upward. The developing cartridge  10  is moved pivotally about an axis of the collar member  61  and diagonally above. Hence, a front end portion of the developing cartridge  10  is lifted upward. 
         [0063]    Subsequently, as shown in  FIG. 9 , the second handle  65  is pulled frontward. Therefore, the collar member  61  is slidingly moved frontward along the upper edge  49  of the side walls  35  of the drum cartridge  8 . Accordingly, the developing cartridge  10  is entirely moved away from the drum cartridge  8 . 
         [0064]    Then, as shown in  FIG. 10 , when the collar member  61  is removed from the upper edge  49 , the developing cartridge  10  is completely separated from the drum cartridge  8 . 
         [0065]    2-4. Assembly of Developing Cartridge to Drum Cartridge 
         [0066]    When the developing cartridge  10  is assembled to the drum cartridge  8 , the second handle  65  is held by the single hand H of the user. Here, as shown in  FIG. 10 , the operation section  71  of the lock member  66  may also be held together with the second handle  65 . Then, the developing roller  9  is positioned above the drum cartridge  8  so as to be directed toward the photosensitive drum  6 . 
         [0067]    Next, the developing cartridge  10  is moved closer to the drum cartridge  8 . As shown in  FIG. 9 , the collar member  61  is disposed on the upper edge  49  of the side walls  35  of the drum cartridge  8 . Subsequently, the developing cartridge  10  is moved rearward. Accordingly, the collar member  61  is slidingly moved on the upper edge  49 . Then, as shown in  FIG. 8 , the collar member  61  is received by the shaft receiving portion  50  ( FIG. 9 ). When the collar member  61  is received by the shaft receiving portion  50 , a position of the rear end portion of the developing cartridge  10  in the upper-to-lower direction is fixed. 
         [0068]    Then, when the second handle  65  is pressed downward, the developing cartridge  10  is pivotally moved about the axis of the collar member  61  downward. The developing cartridge  10  is then placed on the developing cartridge mounting section  37  of the drum cartridge  8 , so that assembly of the developing cartridge  10  to the drum cartridge  8  is completed. In a case where the operation section  71  is held by the hand H together with the second handle  65 , when the hand H is released from the second handle  65  and the operation section  71  after assembly of the developing cartridge  10  to the drum cartridge  8 , the lock member  66  is moved from the unlock position to the lock position by the biasing force of the torsion spring  73 . The hook  69  of the lock member  66  is brought into engagement with the torsion spring  73  from the front side. 
         [0069]    As described above, according to the above-described embodiment, when the developing cartridge  10  is mounted in the drum cartridge  8 , the first handle  46  and the second handle  65  are arranged in confrontation with and spaced apart from each other. Accordingly, when the developing cartridge  10  is mounted in the drum cartridge  8 , the first handle  46  and the second handle  65  can be collectively held by the single hand H. 
         [0070]    Further, when the developing cartridge  10  is mounted in the drum cartridge  8 , the lock member  66  is normally at the lock position. Accordingly, by holding both of the first handle  46  and the second handle  65  collectively, both of the drum cartridge  8  and the developing cartridge  10  can be integrally detached from and attached to the main casing  2 . 
         [0071]    By holding the second handle  65  and the operation section  71  of the lock member  66 , the lock member  66  is moved to the unlock position from the lock position. Hence, separation of the developing cartridge  10  from the drum cartridge  8  is permitted. Accordingly, when the drum cartridge  8  and the developing cartridge  10  are mounted in the main casing  2 , only the developing cartridge  10  can be removed from the main casing  2  while the drum cartridge  8  remains in the main casing  2  by operating the second handle  65  and the operation section  71  of the lock member  66 . Further, after the drum cartridge  8  and the developing cartridge  10  have been integrally removed from the main casing  2 , the developing cartridge  10  can be separated from the drum cartridge  8  by operating the second handle  65  and the operation section  71  of the lock member  66 . 
         [0072]    Accordingly, while the process cartridge  3  can prevent the developing cartridge  10  from undesired separation from the drum cartridge  8 , operability of the second handle  65  and the operation section  71  can also be enhanced when the developing cartridge  10  is separated from the drum cartridge  8 . 
         [0073]    Further, the operation section  71  of the lock member  66  is disposed above the first handle  46  and below the second handle  65 . Therefore, when the first handle  46  and the second handle  65  are collectively held, the operation section  71  is incapable of being operated. Consequently, when the drum cartridge  8  and the developing cartridge  10  are integrally removed from the main casing  2 , occurrence of undesired separation of the developing cartridge  10  from the drum cartridge  8  can be reliably prevented. 
         [0074]    Further, the lock member  66  is supported to the developing cartridge  10 . Therefore, the operation section  71  of the lock member  66  and the second handle  65  provided at the developing cartridge  10  are collectively held without difficulty. 
         [0075]    Further, when the developing cartridge  10  is mounted in the drum cartridge  8 , a downstream side of the developing cartridge  10  in a direction such that the developing cartridge  10  is moved to be mounted in the drum cartridge  8 , that is, the rear side of the developing cartridge  10 , is initially subjected to positioning in the upper-to-lower direction. Subsequently, an upstream side of the developing cartridge  10  in the direction, that is, the front side of the developing cartridge  10 , is subjected to positioning in the upper-to-lower direction. Therefore, vertical positioning of the developing cartridge  10  at its downstream side relative to the drum cartridge  8  can be accurately made. 
         [0076]    In the above embodiment, the process cartridge  3  includes the drum cartridge  8  and the developing cartridge  10 . However, the present invention is also available to a developing unit  110  (cartridge assembly) having a roller cartridge  120  (first cartridge) and a toner cartridge  130  (second cartridge) detachably mounted to the roller cartridge  120 , as schematically shown in  FIG. 11 . 
         [0077]    The developing unit  110  is detachably mounted relative to a main casing (not shown) of an image forming device (not shown). 
         [0078]    The roller cartridge  120  accommodates therein a developing roller  109  and a toner supply roller  119 . The roller cartridge  120  has a casing  121 . The casing  121  is provided with a first handle  146  and an engaged member  143 . The first handle  146  corresponds to the first handle  46  in the above-described embodiment. The engaged member  143  corresponds to the engaged member  43  in the above-described embodiment. 
         [0079]    The toner cartridge  130  has a casing  131  defining therein a toner chamber  132  in which toner is accommodated. The casing  131  is provided with a second handle  165  that corresponds to the second handle  65  in the above-described embodiment. The casing  131  is provided with a lock member  166 , and the lock member  166  includes a hook  169  and an operation section  171 . The lock member  166 , the hook  169 , and the operation section  171  correspond to the lock member  66 , the hook  69 , and the operation section  71  in the above-described embodiment, respectively. The hook  169  is engageable with the engaged member  143  of the roller cartridge  120 . The operation section  171  is disposed below the second handle  165 . When the toner cartridge  130  is mounted in the roller cartridge  120 , the hook  169  of the lock member  166  is engaged with the engaged member  143 . When the toner cartridge  130  is detached from the roller cartridge  120 , the hook  169  is disengaged from the engaged member  143  by operating the operating section  171 . 
         [0080]    While the invention has been described in detail with reference to the embodiment thereof, it would be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention.