Patent Publication Number: US-7711294-B2

Title: Developer cartridge, developing device and image forming apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims priority from Japanese Patent Application No. 2007-051421 filed on Mar. 1, 2007, the entire subject matter of which is incorporated herein by reference. 
   TECHNICAL FIELD 
   Aspects of the present invention relate to an image forming apparatus, and a developer cartridge and a developing device detachably attached to the image forming apparatus. 
   BACKGROUND 
   There has been proposed an image forming apparatus such as a laser printer, in which a toner cartridge is detachably attached to a developing device. 
   For example, JP-A-1-219865 discloses a toner replenishment apparatus, in which a toner cartridge is detachably attached to a developing unit in the image forming apparatus. A toner replenishment port is opened in the bottom of the toner replenishment apparatus. A toner accommodated in the toner replenishment apparatus drops from the toner replenishment port and is supplied to the developing unit. 
   In the toner replenishment apparatus, a first shutter unit is disposed in an upper part of the toner replenishment port. A second shutter unit is disposed in a lower part of the toner replenishment port i.e., the outside of the toner replenishment apparatus. 
   The first shutter unit includes a rotatable rotary shutter. The rotary shutter closes the toner replenishment port from the upper side when a top cover of an image forming apparatus body is in an opened state in a state where the toner replenishment apparatus is attached to the image forming apparatus. As the top cover changes to a closed state, the rotary shutter rotates so as to open the toner replenishment port from the upper side. 
   The second shutter unit includes a slidable slide shutter. The slide shutter opens the toner replenishment port from the lower side by sliding as the toner replenishment apparatus is attached to the image forming apparatus while the slide shutter closes the toner replenishment port from the lower side in a state of detaching the toner replenishment apparatus from the image forming apparatus. 
   The toner replenishment apparatus of JP-A-1-219865 doubly disposes the shutters with respect to the toner replenishment port in order to prevent the toner from leaking from the toner replenishment port. However, the toner may leak from the toner replenishment port due to an influence of vibration by opening and closing at the time of opening and closing the slide shutter outward arranged in the toner replenishment apparatus. 
   SUMMARY 
   Aspects of the invention provide a developer cartridge capable of preventing leakage of developer, a developing device to which the developer cartridge is detachably attached, and an image forming apparatus to which the developer cartridge and developing device are detachably attached. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an exemplary side sectional view showing an image forming apparatus according to an aspect of the present invention; 
       FIG. 2  is an exemplary side sectional view of a developer cartridge and a developing device according to an aspect of the present invention wherein the developing device is in a state in which the developer cartridge is attached to the developing device and a swing arm is in a pressing release position; 
       FIG. 3  is an exemplary side sectional view of the developing device in a state in which the developer cartridge is attached to the developing device and the swing arm is in a pressing position; 
       FIG. 4  is an exemplary side view of the developer cartridge and the developing device wherein the developing device is in a state in which the developer cartridge is attached to the developing device and the swing arm is in the pressing release position; 
       FIG. 5  is an exemplary side view of the developing device in a state in which the developer cartridge is attached to the developing device and the swing arm is in the pressing position; 
       FIG. 6  is a schematic perspective view of the developing device as viewed from a diagonal front right side; 
       FIG. 7  is a schematic perspective view of the developing device, as viewed from a diagonal front right side, in a state in which the developer cartridge is detached from the developing device; 
       FIG. 8  is a schematic perspective view of the developing device in which a shutter is omitted in  FIG. 7 ; 
       FIG. 9  is an exemplary perspective view of an inside cabinet of the developer cartridge as viewed from a diagonal back left side; 
       FIG. 10  is an exemplary perspective view of the developer cartridge, as viewed from the diagonal back left side, in a state in which the inside cabinet is in an opened position and a cover is in a retracted position; 
       FIG. 11  is an exemplary perspective view of the developer cartridge, as viewed from the diagonal back left side, in a state in which the inside cabinet is in a closed position and the cover is in an opened position; and 
       FIG. 12  is an exemplary perspective view of the developer cartridge, as viewed from the diagonal back left side, in a state in which the inside cabinet is in the closed position and the cover is in a closed position. 
   

   DETAILED DESCRIPTION 
   &lt;General Overview&gt; 
   According to an aspect of the present invention, there is provided a developer cartridge including: a cartridge cabinet that accommodates developer and includes an opening for enabling communication between an inside of the cartridge cabinet and an outside of the cartridge cabinet; a shutter that opens and closes the opening; and a cover that is arranged outside the cartridge cabinet and is movable between a closed position for closing the opening and an opened position for opening the opening, the opened position being located lower than the closed position, wherein the cover is movable such that a first end of the cover is in intimate contact with the cartridge cabinet while a second end of the cover is separated from the cartridge cabinet, the first end being farthest from the opening in the cover located in the opened position, and the second end being nearest to the opening in the cover located in the opened position. 
   According to another aspect of the present invention, there is provided a developing device including: a developer cartridge including: a cartridge cabinet that accommodates developer and includes an opening for enabling communication between an inside of the cartridge cabinet and an outside of the cartridge cabinet; a shutter that opens and closes the opening; and a cover that is arranged outside the cartridge cabinet and is movable between a closed position for closing the opening and an opened position for opening the opening, the opened position being located lower than the closed position, wherein the cover is movable such that a first end of the cover is in intimate contact with the cartridge cabinet while a second end of the cover is separated from the cartridge cabinet, the first end being farthest from the opening in the cover located in the opened position, and the second end being nearest to the opening in the cover located in the opened position; a developing cabinet, the developer cartridge being attachable to and detachable from the developing cabinet; and a developer carrier that is supported in the developing cabinet and carries the developer to a photosensitive member, wherein the developer cartridge further includes a protrusion part for moving the cover from the closed position to the opened position according to attachment of the developer cartridge to the developing cabinet. 
   According to still another aspect of the present invention, there is provided an image forming apparatus including a developing device, the developing device including: a developer cartridge including: a cartridge cabinet that accommodates developer and includes an opening for enabling communication between an inside of the cartridge cabinet and an outside of the cartridge cabinet; a shutter that opens and closes the opening; and a cover that is arranged outside the cartridge cabinet and is movable between a closed position for closing the opening and an opened position for opening the opening, the opened position being located lower than the closed position, wherein the cover is movable such that a first end of the cover is in intimate contact with the cartridge cabinet while a second end of the cover is separated from the cartridge cabinet, the first end being farthest from the opening in the cover located in the opened position, and the second end being nearest to the opening in the cover located in the opened position; a developing cabinet, the developer cartridge being attachable to and detachable from the developing cabinet, the developing cabinet including an operation member, wherein the protrusion part moves the cover from the closed position to the opened position by being pressed on the operation member according to attachment of the developer cartridge to the developing cabinet; and a developer carrier that is supported in the developing cabinet and carries the developer to a photosensitive member, wherein the developer cartridge further includes a protrusion part for moving the cover from the closed position to the opened position according to attachment of the developer cartridge to the developing cabinet. 
   &lt;Illustrative Aspects&gt; 
   (Image Forming Apparatus) 
     FIG. 1  is an exemplary side sectional view showing an image forming apparatus according to an aspect of the present invention.  FIG. 2  is an exemplary side sectional view of a developer cartridge and a developing device wherein the developing device is in a state in which the developer cartridge is attached to the developing device and a swing arm is in a pressing release position.  FIG. 3  is an exemplary side sectional view of the developing device in a state in which the developer cartridge is attached to the developing device and the swing arm is in a pressing position. 
   The laser printer  1  includes a feeder unit  4  for feeding a sheet  3  to the inside of a body casing  2 , an image forming unit  5  for forming an image on the fed sheet  3 , and a sheet discharge part  6  for delivering the sheet  3  on which the image is formed as shown in  FIG. 1 . 
   (1) Body Casing 
   The body casing  2  is formed in a box shape, and an opening is formed in a sidewall of one side of the body casing  2 , and a front cover  7  for opening and closing an opening is disposed. By opening a front cover  7 , a developing device  17  (described below) can be attached to and detached from the body casing  2 . 
   In addition, in the following description, the side in which the front cover  7  is disposed is referred to as a front side (front face side) and the opposite side is referred to as a back side (rear side). The front side of a sheet thickness direction in  FIG. 1  is referred to as a left side, and the back side of the sheet thickness direction in  FIG. 1  is referred to as a right side. Incidentally, left and right directions are synonymous with a width direction. Further, in the following description related to a developing device  17  and a developer cartridge  31 , a state in which a frame side passage port  34  and a cartridge side passage port  47  described below face in a horizontal direction is used as the reference. 
   (2) Feeder Unit 
   The feeder unit  4  includes a sheet feeding tray  9 , a sheet feeding roller  10 , a sheet feeding pad  11 , sheet powder removal rollers  12  and  13 , register rollers  14 , and a sheet press plate  15 . Then, the uppermost sheet  3  of the sheet press plate  15  is fed out one at a time by the sheet feeding roller  10  and the sheet feeding pad  11  and passes through various rollers  12  to  14  and thereafter, is conveyed to a transfer position (described below) of the image forming unit  5 . 
   (3) Image Forming Unit 
   The image forming unit  5  includes a scanner unit  16 , the developing device  17 , and a fixing part  18 . In  FIG. 1 , the developing device  17  is embodied in the form of a process cartridge by way of an example. However, one of ordinary skill in the art will appreciate that the present inventive concept will apply equally to any unit which may be used for developing. 
   (3-1) Scanner Unit 
   The scanner unit  16  is arranged in an upper part of the inside of the body casing  2 , and includes a laser light emitting part (not shown), a polygon mirror  19  rotated and driven, plural lenses  20  and plural reflecting mirrors  21 . A laser beam based on image data emitted from the laser light emitting part is reflected by the polygon mirror  19  and passes through or is reflected by the plural lenses  20  and the plural reflecting mirrors  21  and is scanned to a surface of a photoconductive drum  25  (described below) of the developing device  17  as shown by a chain line. 
   (3-2) Developing Device 
   The developing device  17  is arranged under the scanner unit  16  in the inside of the body casing  2  and is detachably attached to the body casing  2 . 
   As shown in  FIGS. 2 and 3 , the developing device  17  includes a process frame  22  as one example of a developing cabinet in which a transfer path  29  for permitting passage of the sheet  3  is formed, and the developer cartridge  31  detachably attached to a cartridge receiving part  33  of the process frame  22 . 
   In the process frame  22 , a partition wall  57  extending in upper and lower directions is disposed in substantially the center position in front and back directions of the process frame  22 , and the backside portion of the partition wall  57  forms a developing part  32  and the front side portion of the partition wall  57  forms the cartridge receiving part  33  described above. The frame side passage port  34  is formed in the partition wall  57 . 
   The photoconductive drum  25  as one example of a photosensitive member, a scorotron-type charger  26 , a transfer roller  28 , an auger  35 , a supply roller  36 , a developing roller  37  as one example of a developer carrier, and a layer thickness regulating blade  38  are mounted inside the developing part  32 . 
   The photoconductive drum  25  is rotatably supported in the process frame  22 . The scorotron-type charger  26  is supported in the process frame  22  over the photoconductive drum  25  in a state spaced from the photoconductive drum  25 . The transfer roller  28  is arranged as opposed to the photoconductive drum  25  from the lower side of the photoconductive drum  25  and is rotatably supported in the process frame  22 . The developing roller  37  is longitudinal in the width direction and is arranged as opposed to the front side of the photoconductive drum  25 . The supply roller  36  is arranged as opposed to the front side of the developing roller  37 . The developing roller  37  and the supply roller  36  are rotatably supported in the process frame  22 . The layer thickness regulating blade  38  includes a leaf spring member  45  formed in a thin plate shape, and a pressure contact rubber  46  disposed in the lower end of the leaf spring member  45 . The upper end of the leaf spring member  45  is fixed to the process frame  22 , and the pressure contact rubber  46  presses a surface of the developing roller  37  by elastic force of the leaf spring member  45 . The auger  35  is arranged as opposed to the frame side passage port  34  in the back side of the frame side passage port  34 . The auger  35  includes an auger shaft  39 , and a screw  40  disposed around the auger shaft  39 . The auger shaft  39  is arranged so that a center portion of the shaft  39  extends along the width direction, and is rotatably supported in the process frame  22  over the supply roller  36 . 
   The developer cartridge  31  is detachably attached to the process frame  22  in the cartridge receiving part  33 . In addition, a direction of attaching and detaching the developer cartridge  31  to and from the process frame  22  is substantially a horizontal direction (see an arrow of a thick line of  FIG. 2 ). The developer cartridge  31  is formed in substantially a cylindrical shape. A cartridge side passage port  47  (described below) for communicating the inside to the outside is formed in the developer cartridge  31 . 
   An agitator  93  (described below) is disposed inside the developer cartridge  31  for accommodating developer inside the developer cartridge  31 . In the image forming apparatus  1  of the aspect, the developer includes a nonmagnetic one-component toner with positive electrification. 
   Referring to  FIG. 3 , the developer accommodated inside of the developer cartridge  31  is agitated by rotation of the agitator  93  and is received from the cartridge side passage port  47  to the frame side passage port  34  and is discharged to the inside of the developing part  32 . The discharged developer is supplied to the supply roller  36  while being transported from the center of the width direction to both sides of the width direction by rotation of the auger  35 . Also, a part of the developer is returned to the inside of the developer cartridge  31  through the frame side passage port  34  and the cartridge side passage port  47 . Consequently, circulation of the developer between the developer cartridge  31  and the developing part  32  of the process frame  22  is ensured. 
   The developer supplied to the supply roller  36  is supplied to the developing roller  37  by rotation of the supply roller  36 . At this time, the developer is frictionally electrified in positive polarity between the supply roller  36  and the developing roller  37 . Subsequently, the developer supplied to the developing roller  37  is carried as a thin layer on a surface of the developing roller  37  while with rotation of the developing roller  37 , the developer enters between the pressure contact rubber  46  and the developing roller  37  and a layer thickness of the developer is regulated between the pressure contact rubber  46  and the developing roller  37 . 
   Then, after a surface of the photoconductive drum  25  is first positively electrified uniformly by the scorotron-type charger  26  with rotation of the photoconductive drum  25 , the surface is exposed by a laser beam from the scanner unit  16  and an electrostatic latent image based on image data is formed. When the developer carried on a surface of the developing roller  37  oppositely makes contact with the photoconductive drum  25  by rotation of the developing roller  37 , the developer is carried to the electrostatic latent image formed on the surface of the photoconductive drum  25 . Consequently, the electrostatic latent image is developed (imaged) and a developer image is carried on the surface of the photoconductive drum  25 . The developer image is transferred to the sheet  3  conveyed between the photoconductive drum  25  and the transfer roller  28  (a transfer position) in the transfer path  29 . 
   (3-3) Fixing Part 
   The fixing part  18  is disposed at the back of the developing device  17  as shown in  FIG. 1 . The fixing part  18  includes a heating roller  48 , a pressurizing roller  49  brought into pressure contact with the heating roller  48  from the lower side, and a pair of conveying rollers  50  arranged in the back side of their rollers. 
   In the fixing part  18 , the developer transferred to the sheet  3  in the transfer position is thermally fixed while the sheet  3  passes between the heating roller  48  and the pressurizing roller  49  and thereafter, the sheet  3  is conveyed to the sheet discharge part  6  by the pair of conveying rollers  50 . 
   (4) Sheet Discharge Part 
   The sheet discharge part  6  includes a sheet discharge path  51 , sheet delivery rollers  52 , and a sheet delivery tray  53 . The sheet  3  conveyed from the fixing part  18  to the sheet discharge path  51  is conveyed from the sheet discharge path  51  to the sheet delivery rollers  52  and is delivered on the sheet delivery tray  53  by the sheet delivery rollers  52 . 
   (Developing Device) 
     FIG. 4  is an exemplary side view of a developer cartridge and the developing device wherein the developing device is in a state in which the developer cartridge is attached to the developing device and the swing arm is in a pressing release position.  FIG. 5  is an exemplary side view of the developing device in a state in which the developer cartridge is attached to the developing device and the swing arm is in a pressing position.  FIG. 6  is a schematic perspective view of the developing device as viewed from a diagonal front right side.  FIG. 7  is a schematic perspective view of the developing device, as viewed from the diagonal front right side, in a state in which the developer cartridge is detached from the developing device.  FIG. 8  is a schematic perspective view of the developing device in which a shutter is omitted in  FIG. 7 .  FIG. 9  is an exemplary perspective view of an inside cabinet of the developer cartridge as viewed from a diagonal back left side.  FIG. 10  is an exemplary perspective view of the developer cartridge, as viewed from the diagonal back left side, in a state in which the inside cabinet is in an opened position and a cover is in a retracted position.  FIG. 11  is an exemplary perspective view of the developer cartridge, as viewed from the diagonal back left side, in a state in which the inside cabinet is in a closed position and the cover is in an opened position.  FIG. 12  is an exemplary perspective view of the developer cartridge, as viewed from the diagonal back left side, in a state in which the inside cabinet is in the closed position and the cover is in a closed position. 
   (1) Process Frame 
   The process frame  22  integrally includes the developing part  32  and the cartridge receiving part  33  as shown in  FIG. 7 . 
   (1-1) Developing Part 
   The developing part  32  integrally includes an upper wall  54 , a bottom wall  55 , both side walls  56  and the partition wall  57  as shown in  FIGS. 2 ,  3  and  7 . Both the side walls  56  are arranged as opposed to each other at a spacing in the width direction. Each of the side walls  56  is arranged along the front and back directions. 
   The developing roller  37  is supported in the process frame  22  by being rotatably supported in the front side of both the side walls  56 . 
   The supply roller  36  is supported in the process frame  22  by being rotatably supported in the front side of both the side walls  56  in the front side of the developing roller  37 . 
   The auger  35  is supported in the process frame  22  by rotatably supporting the auger shaft  39  in the front side of both the side walls  56  in the upper side of the supply roller  36 . 
   In the partition wall  57 , a curved portion along an outer peripheral surface of the developer cartridge  31  is formed in the middle of the upper and lower directions as shown in  FIGS. 2 and 3 . 
   The frame side passage ports  34  described above are formed in the curved portion of the partition wall  57  as shown in  FIG. 8 . 
   Concretely, three frame side passage ports  34  are formed at a spacing in the width direction. Each of the frame side passage ports  34  is formed in substantially a rectangular shape elongated in the width direction. The frame side passage port  34  formed in the center of the width direction of the partition wall  57  among the frame side passage ports  34  is used as a frame side supply port  60  and the frame side passage ports  34  of both sides of the width direction of the frame side supply port  60  are used as frame side return ports  61 . 
   The outside ends of the width direction of the frame side return ports  61  are arranged in the inside of the width direction (center side of the width direction) from the outside ends of the width direction of a roller portion of the supply roller  36 . 
   A frame side seal  62  for preventing leakage of the developer from the frame side passage ports  34  in the peripheral edges of the frame side passage ports  34  is disposed in the curved portion of the partition wall  57 . 
   The frame side seal  62  is formed from an elastic material such as felt in a band shape extending in the width direction, and a notched portion is formed in correspondence with each of the frame side passage ports  34 . The frame side seal  62  is pasted along the width direction so that each of the notched portions is opposed to each of the frame side passage ports  34  in the middle of the upper and lower directions of the partition wall  57 . 
   Consequently, the frame side seal  62  is disposed on a surface (front) of the curved portion of the partition wall  57  so as to coat the peripheral edge of each of the frame side passage ports  34  and continue between each of the frame side passage ports  34 . In addition, the frame side seal  62  is not represented in the drawings other than  FIG. 8  for convenience of description. 
   (1-2) Cartridge Receiving Part 
   The cartridge receiving part  33  includes both side plates  63  and a bottom plate  64  as shown in  FIG. 7 . Both the side plates  63  and the bottom plate  64  of the cartridge receiving part  33  are integrally formed continuously with both the side walls  56  and the bottom wall  55  of the developing part  32 . Shutter support parts  65  are disposed on inside surfaces of the width direction of both the side plates  63 . The shutter support part  65  is formed in substantially a rectangular shape inward bulging from an inside surface of the width direction of both the side plates  63  and is disposed so as to extend in the upper and lower directions in the back ends of both the side plates  63 . 
   A shutter guide part  144  is disposed on an inside surface of the width direction of each of the shutter support parts  65 . Each of the shutter guide parts  144  forms a protrusion stripe inward bulging from the inside surface of the width direction of the shutter support part  65 , and is arranged as opposed to the curved portion of the partition wall  57  at a slight spacing in the front and back directions. Each of the shutter guide parts  144  is formed in a curved shape with substantially the same curvature as that of the curved portion of the partition wall  57 . 
   Also, an upper end surface of each of the shutter support parts  65  is arranged in a position slightly lower than the upper edge of each of the side plates  63 . The upper end surface of each of the shutter support parts  65  forms an upper side fixed part  66 . 
   Also, in the bottom plate  64 , a lower side fixed part  67  slightly protruding to the front side is formed in the center of the width direction of the front edge. 
   Also, a shutter  68  for opening and closing the frame side passage ports  34  is disposed in the cartridge receiving part  33 . 
   The shutter  68  is formed in substantially a rectangular shape extending in the width direction and is formed in a curved shape with substantially the same curvature as that of the curved portion of the partition wall  57 . The shutter  68  is formed so as to extend between each of the shutter guide parts  144  in the width direction and extend slightly shorter than each of the shutter guide parts  144  in the upper and lower directions. Also, three shutter opening parts  69  capable of being opposed to the frame side passage ports  34  corresponding to each of the frame side passage ports  34  are formed in the shutter  68 . 
   The shutter  68  is arranged as opposed to the curved portion of the partition wall  57 , and both ends of a width direction of the shutter  68  are slidably pinched between the partition wall  57  and each of the shutter guide parts  144 . 
   Consequently, the shutter  68  is supported slidably along the each of the shutter guide parts  144  in the upper and lower directions between an opened position (see  FIG. 3 ) in which the frame side passage ports  34  are opened and a closed position (see  FIGS. 2 and 7 ) in which the frame side passage ports  34  are closed. When the shutter  68  is in the opened position, each of the frame side passage ports  34  is opposed to the corresponding shutter opening parts  69  and is opened to the outside (front side). When the shutter  68  is in the closed position, each of the frame side passage ports  34  is closed from the front side by the portions of the lower sides than the shutter opening parts  69  in the shutter  68 . 
   Also, a swing arm  70  as one example of an operation member is disposed in the cartridge receiving part  33 . The swing arm  70  is formed in substantially a U shape in the case of being viewed from the plane. The swing arm  70  integrally includes a grasp bar  71  extending in the width direction, and arm side plates  72  backward extending from both ends of the width direction of a grasp bar  71 . 
   A boss  73  outward protruding in the width direction is disposed in the back end of each of the arm side plates  72 . Each of the bosses  73  is rotatably supported in a circular hole  74  formed in each of the side plates  63 . 
   Also, a receiving recessed part  75  notched so as to be recessed to the lower side is formed in the upper side edge of the back end of each of the arm side plates  72 . 
   Also, in an inside surface of the width direction of each of the arm side plates  72 , a press recessed part  142  notched so as to be recessed from the upper side edge of each of the arm side plates  72  to the lower side is formed in a position of the front side from the receiving recessed part  75 . 
   A grasp part  76  recessed to the upper side is formed in the center of the width direction of the grasp bar  71 . Also, press protrusion parts  77  are disposed in both ends of the width direction of the grasp bar  71 . 
   Using the boss  73  of each of the arm side plates  72  as a fulcrum, the swing arm  70  swings between a pressing release position (see  FIGS. 2 ,  4 ,  7  and  8 ) in which the lower edge of each of the arm side plates  72  makes contact with the front edge of the bottom plate  64  and a pressing position (see  FIGS. 3 ,  5  and  6 ) in which the developer cartridge  31  is pressed from the front side when the developer cartridge  31  is received in the cartridge receiving part  33 . 
   (2) Developer Cartridge 
   The developer cartridge  31  includes an inside cabinet  81  as one example of a shutter with substantially a cylindrical shape for accommodating the developer, an outside cabinet  82  with substantially a cylindrical shape for receiving the inside cabinet  81 , and a cover unit  100  arranged outside the outside cabinet  82  as shown in  FIGS. 9 to 12 . The inside cabinet  81  and the outside cabinet  82  function as one example of a cartridge cabinet. 
   (2-1) Inside Cabinet 
   The inside cabinet  81  integrally includes a cylindrical inside peripheral wall  83  extending in the width direction, and circular plate-shaped inside side walls  84  for closing both ends of the width direction of the inside peripheral wall  83  as shown in  FIG. 9 . 
   A boss part  85  with a circular thick plate shape outward bulging in the width direction is disposed in the center of each of the inside side walls  84 . A through hole  120  is formed in a circular center position of the left boss part  85 . 
   Also, a slide protrusion  86  is disposed in the radial outside from the boss part  85  and an upper side portion of each of the inside side walls  84 . The slide protrusion  86  is formed in a circular arc shape (circular arc shape with a center angle of about 60°) in the case of being viewed from the side along an outer peripheral surface of the inside side wall  84 , and is disposed so as to protrude from the inside side wall  84  to the outside of the width direction. 
   Also, a cartridge protrusion  121  is disposed in the side (specifically, the lower side of the boss part  85 ) opposite to the slide protrusion  86  with respect to the boss part  85  in each of the inside side walls  84 . The cartridge protrusion  121  is formed in a rectangular shape in the case of being viewed from the side and is disposed so as to protrude from the inside sidewall  84  to the outside of the width direction. 
   Also, a pair of pinch protrusions  87  radially protruding from a peripheral end surface are disposed in a back side portion of each of the inside side walls  84 . The pair of pinch protrusions  87  are arranged at a spacing (spacing corresponding to a circumferential length of the shutter  68 ) in a circumferential direction mutually in the peripheral end surface of each of the inside side walls  84 . 
   In the inside peripheral wall  83 , inside passage ports  89  as one example of inside openings for forming the cartridge side passage ports  47  are formed in a surrounded portion  88  surrounded by the pair of pinch protrusions  87  (four pinch protrusions  87 ) arranged in both sides of the width direction. 
   The inside passage ports  89  are formed in the upper side portion of the surrounded portion  88 . Concretely, three inside passage ports  89  are formed at a spacing in the width direction. Each of the inside passage ports  89  is formed in substantially a rectangular shape elongated in the width direction. The inside passage port  89  formed in the center of the width direction among the inside passage ports  89  is used as an inside supply port  90  and the inside passage ports  89  of both sides of the width direction of an inside supply port  90  are used as inside return ports  91 . 
   As shown in  FIGS. 2 and 3 , the agitator  93  described above is disposed inside the inside cabinet  81 . The agitator  93  includes an agitator shaft  94  extending in the width direction, and an agitating blade  95  extending from the agitator shaft  94  to the radial outside. The agitator shaft  94  is rotatably supported in both the inside side walls  84 . Specifically, a passive gear  122  shown in  FIG. 9  is mounted in the left end of the agitator shaft  94 . The passive gear  122  is formed in a columnar shape and is exposed from the through hole  120  of the boss part  85  described above to the outside. Also, a recessed part (called an engaging recessed part  123 ) recessed to the right side and having substantially an 8 shape in the case of being viewed from the left side is formed in a left side surface of the passive gear  122 . At the time of forming an image, the passive gear  122  is joined to a driving gear (not shown) of a motor (not shown) of the body casing  2  in the engaging recessed part  123 . As a result of that, driving force from the motor (not shown) is transmitted to the agitator shaft  94  and the agitator  93  (concretely, the agitating blade  95 ) rotates around the agitator shaft  94 . Consequently, the developer accommodated inside of the developer cartridge  31  is agitated. 
   (2-2) Outside Cabinet 
   The outside cabinet  82  is formed slightly larger than the inside cabinet  81  in the width and radial directions in order to rotatably receive the inside cabinet  81 . The outside cabinet  82  integrally includes an outside peripheral wall  101  with substantially a cylindrical shape extending in the width direction, and substantially semicircular plate-shaped outside side walls  102  for closing substantially upper half portions in both ends of the width direction of the outside peripheral wall  101  as shown in  FIG. 10 . 
   A circular boss hole  103  for receiving the boss part  85  is formed in a circular center position of each of the outside side walls  102 . Also, a slide hole  104  into which the slide protrusion  86  is inserted is formed in an upper side portion of each of the outside side walls  102 . The slide hole  104  is arranged as opposed to the slide protrusion  86  in the width direction. The slide hole  104  is formed in a circular arc shape with a circumferential length longer than that of the slide protrusion  86  in the case of being viewed from the side. 
   Also, a back side portion of each of the outside side walls  102  is formed so as to be further recessed to the inside of the width direction along the peripheral edge of the outside side wall  102 . In addition, the recessed portion is called a recessed part  124 . In each of the outside side walls  102 , a backward protruding upper side part  105  to be fixed is formed in the upper end of the recessed part  124 . A positioning boss  106  outward protruding in the width direction is disposed in the back end of the upper side part  105  to be fixed. 
   Also, in the recessed part  124  of each of the outside side walls  102 , a guide rail  125  as one example of a guide groove is formed under the upper side part  105  to be fixed. The guide rail  125  is formed so as to notch the outside peripheral edge in the recessed part  124  of each of the outside side walls  102 . Also, a depth (notch depth) of the guide rail  125  is formed so as to become deep as the guide rail  125  is located from the lower side toward the upper side (the side of the upper side part  105  to be fixed). 
   Also, forward bulging pressed parts  107  are disposed on the front sides (both ends of the width direction of the front side of the outside peripheral wall  101 ) of peripheral end surfaces of each of the outside side walls  102  as shown in  FIG. 7 . The pressed part  107  is formed in substantially a rectangular shape in the case of being viewed from the front and substantially a circular arc shape extending from the front side of each of the outside side walls  102  to the lower side in the case of being viewed from the side. 
   Four elongated holes  108  into which the pair of pinch protrusions  87  (four pinch protrusions  87 ) are respectively inserted are formed in both ends of the width direction in the outside peripheral wall  101  as shown in FIG.  10 . Each of the elongated holes  108  is arranged as opposed to each of the pinch protrusions  87  in a radial direction. Each of the elongated holes  108  is formed in substantially a rectangular shape extending in the upper and lower directions in the case of being viewed from the rear and is formed in a length corresponding to a swing range between the opened position and the closed position of the shutter  68  described above. Here, the guide rail  125  is positioned between the elongated holes  108  arranged in a circumferential direction. 
   Also, in the outside peripheral wall  101 , outside passage ports  109  as one example of openings for forming the cartridge side passage ports  47  are formed between the four elongated holes  108  (between the two elongated holes  108  of the upper side and the two elongated holes  108  of the lower side). 
   The three outside passage ports  109  are formed at a spacing in the width direction. Each of the outside passage ports  109  is formed in substantially a rectangular shape elongated in the width direction. The outside passage port  109  formed in the center of the width direction among the outside passage ports  109  is used as an outside supply port  110  and the outside passage ports  109  of both sides of the width direction of the outside supply port  110  are used as outside return ports  111 . 
   Here, the guide rails  125  are respectively formed in both ends of the width direction of the outside passage ports  109  in the outside cabinet  82 , that is, in the left side of the left outside return port  111  and the right side of the right outside return port  111 . 
   The outside supply port  110  is opposed to the frame side supply port  60  and the two outside return ports  111  are opposed to the two frame side return ports  61  in a state of attaching the developer cartridge  31  to the process frame  22  (see  FIGS. 8 and 10 ). 
   Also, in the front side of the outside peripheral wall  101 , a grip part  113  is disposed in the center of the width direction as shown in  FIG. 7 . 
   The grip part  113  includes an upper grasp plate  114  with substantially a rectangular shape forward protruding from the outside peripheral wall  101 , and a locking arm  115  with substantially a J shape in the case of being viewed from the side downward extending from the upper grasp plate  114 . The upper end of the locking arm  115  is swingably supported in a support shaft  116  disposed in the upper grasp plate  114 . A locking claw  117  for locking in the lower side fixed part  67  is disposed in the lower end of the locking arm  115 . A lower grasp plate  118  with substantially a rectangular shape forward protruding is disposed in the vicinity of the upper end of the locking arm  115 . The lower grasp plate  118  is arranged so as to extend in spaced parallel with the upper grasp plate  114 . 
   A compression spring (not shown) for urging the grasp plates in a direction of separation is interposed between the upper grasp plate  114  and the lower grasp plate  118 . 
   (2-3) Cover Unit 
   The cover unit  100  includes a cover  126  and a support lever  127  as shown in  FIG. 12 . In addition, in description of the cover unit  100 , an attitude of the cover unit  100  in  FIG. 12  is used as the reference. 
   The cover  126  is formed in substantially a rectangular plate shape extending in the width direction and is formed in a circular arc shape with substantially the same curvature as that of the outside peripheral wall  101 . Both ends of the width direction of the upper edge of the cover  126 , specifically, the portions matching with the elongated holes  108  in the width direction are notched downward in a rectangular shape (this portion is called a notched portion  132 ). 
   In the cover  126 , a cover seal  131  as one example of a seal member is disposed on a surface of the center side (front side) of the circular arc. The cover seal  131  has a shape similar to that of the cover  126  and is formed by a sheet such as a sponge. The surface of the circular arc center side of the cover  126  is coated with the cover seal  131 . In addition, the cover seal  131  is hereinafter regarded as a part of the cover  126 . 
   Also, in both ends of the width direction of the cover  126 , an engaging part  128  is integrally disposed in the upper end and a cover protrusion  129  is integrally disposed in substantially the center of the upper and lower directions and a joint part  130  is integrally disposed in the lower end. 
   Each of the engaging parts  128  is protruded from both ends of the width direction of the cover  126  toward the circular arc center side (front side) of the cover  126 . Also, each of the engaging parts  128  is formed so as to bulge in a circular arc shape in the protrusion direction in the case of being viewed from the side. 
   Each of the cover protrusions  129  is formed in a rectangular shape in the case of being viewed from the side and is protruded from both ends of the width direction of the cover  126  toward the outside of the width direction. 
   Each of the joint parts  130  is protruded from both ends of the width direction of the cover  126  toward a direction (back side) separated from the circular arc center of the cover  126 . Also, each of the joint parts  130  is formed so as to bulge in a circular arc shape in the protrusion direction in the case of being viewed from the side, and a joint hole (not shown) recessed to the inside of the width direction is disposed in an outside surface of the width direction. 
   The support levers  127  are respectively disposed in both end sides of the width direction of the cover  126 . Each of the support levers  127  is formed in substantially an inverted L shape in the case of being viewed from the left side, and integrally includes substantially bar-shaped first arm part  133  and second arm part  134 . 
   In the first arm part  133 , one end (upper end) is formed in a ring shape with a diameter larger than that of the boss part  85  and a lever first protrusion  135  is disposed between one end and the other end (lower end). The lever protrusion  135  is formed in a rectangular shape in the case of being viewed from the side and is disposed so as to protrude from the first arm part  133  to the outside of the width direction. 
   In the second arm part  134 , a pressed protrusion  136  as one example of a protrusion part is disposed in one end (front end) and a joint protrusion (not shown) is disposed in the other end (back end) and a lever second protrusion  137  is disposed between one end and the other end (specifically, a position deviating to the side of the other end). The pressed protrusion  136  is formed in a columnar shape protruding from the second arm part  134  to the outside of the width direction. The joint protrusion (not shown) is formed in a columnar shape protruding from the second arm part  134  to the inside of the width direction. The lever second protrusion  137  is downward protruded from the second arm part  134  to the inside of the width direction. 
   The other end of the first arm part  133  is connected between one end and the other end (specifically, a position deviating to the side of one end) of the second arm part  134 . 
   The cover  126  is supported in each of the support levers  127  in both ends of the width direction of the cover  126 . 
   Concretely, by inserting the joint protrusion (not shown) of each of the support levers  127  into the corresponding joint hole (not shown) in the cover  126 , the cover  126  is joined to each of the support levers  127  in each of the joint parts  130  and is swingably supported. Here, a coil spring  138  as one example of a second urging member having two arm parts is wound on the joint protrusion (not shown) of each of the support levers  127 . In the coil spring  138 , one arm part is locked in the corresponding cover protrusion  129  and the other arm part is locked in the lever second protrusion  137  of each of the corresponding support levers  127 . Consequently, the cover  126  is always urged to the circular arc center side. 
   (2-4) Relative Arrangement of Inside Cabinet and Outside Cabinet 
   The inside cabinet  81  is rotatably received inside the outside cabinet  82 . 
   Concretely, an outer peripheral surface of the inside peripheral wall  83  is inward fitted slidably in a circumferential direction with respect to an inner peripheral surface of the outside peripheral wall  101  (see  FIGS. 2 and 3 ). The boss part  85  is rotatably supported in the boss hole  103 . The slide protrusion  86  is inserted into the slide hole  104 . Each of the pinch protrusions  87  is inserted into each of the elongated holes  108 , and each of the pinch protrusions  87  is protruded from each of the elongated holes  108  to the outside of a radial direction (see  FIG. 11 ). 
   The inside cabinet  81  permits relative rotates using the boss part  85  as a fulcrum between a closed position (see  FIGS. 2 and 11 ) in which the inside passage ports  89  are not opposed to the outside passage ports  109  and an opened position (see  FIGS. 3 and 10 ) in which the inside passage ports  89  are opposed to the outside passage ports  109  with respect to the outside cabinet  82 . 
   When the inside cabinet  81  is arranged in the closed position, as shown in  FIG. 11 , each of the slide protrusions  86  is arranged in the front end of each of the slide holes  104 , and each of the pinch protrusions  87  is arranged in the upper end of each of the elongated holes  108 , and the inside passage ports  89  are arranged in the side upper than the outside passage ports  109  (see  FIG. 2 ), and the outside passage ports  109  are closed by the lower side portion of the surrounded portion  88 . Then, the inside cabinet  81  is relatively rotated in a direction (lower side) in which the inside passage ports  89  move toward the outside passage ports  109  with respect to the outside cabinet  82  using the boss part  85  as a fulcrum (see  FIG. 3 ). Then, each of the slide protrusions  86  slides each of the slide holes  104  from the front end toward the back end, and each of the pinch protrusions  87  slides each of the elongated holes  108  from the upper end toward the lower end. 
   Thereafter, when each of the slide protrusions  86  abuts on the back edge of each of the slide holes  104  and each of the pinch protrusions  87  abuts on the lower edge of each of the elongated holes  108 , the inside cabinet  81  is arranged in the opened position as shown in  FIG. 10 . 
   When the inside cabinet  81  is arranged in the opened position, each of the slide protrusions  86  is arranged in the back end of each of the slide holes  104 , and each of the pinch protrusions  87  is arranged in the lower end of each of the elongated holes  108 , and the inside passage ports  89  are opposed to the outside passage ports  109  and these passage ports are communicated and opened. 
   In addition, when the inside cabinet  81  is relatively rotated in a direction in which the inside passage ports  89  rise from the outside passage ports  109  with respect to the outside cabinet  82  using the boss part  85  as the fulcrum, each of the slide protrusions  86  abuts on the front edge of each of the slide holes  104  and each of the pinch protrusions  87  abuts on the upper edge of each of the elongated holes  108  and the inside cabinet  81  is arranged in the closed position as shown in  FIG. 11 . 
   In this manner, the inside cabinet  81  opens and closes the outside passage ports  109 . 
   In addition, each of the cartridge protrusion  121  disposed in the inside cabinet  81  always protrudes to the outside of the width direction in the lower side of the corresponding outside side wall  102 . 
   (2-5) Relative Arrangement of Cover Unit with Respect to Inside Cabinet and Outside Cabinet 
   The cover unit  100  is rotatably mounted with respect to the inside cabinet  81  and the outside cabinet  82 . 
   Specifically, one end of the ring shape in the first arm part  133  of each of the support levers  127  is loosely fitted in the boss part  85  in the inside of the width direction of the outside side walls  102 , and the cover unit  100  is supported in the inside cabinet  81  in each of the boss parts  85 . In this state, the cover unit  100  is rotatable with respect to the inside cabinet  81  and the outside cabinet  82 . 
   In addition, the lever first protrusion  135  of each of the first arm parts  133  always protrudes to the outside of the width direction in the lower side of the corresponding outside side wall  102 . 
   The cover  126  is also rotatable with respect to the inside cabinet  81  and the outside cabinet  82  with the cover unit  100 . The cover  126  is rotatably supported in the inside cabinet  81  around each of the boss parts  85  (specifically, around a line through the rotation shaft of the inside cabinet  81 ) between the closed position (see  FIG. 12 ) and the opened position (see  FIGS. 10 and 11 ). 
   Concretely, when the cover  126  is in the closed position, as shown in  FIG. 12 , the outside passage ports  109  are closed from the outside and the lower pinch protrusion  87  of the pair of pinch protrusions  87  is covered from the outside. In contrast, when the cover  126  is in the opened position, as shown in  FIG. 11 , the cover  126  is located in the side lower than the closed position and the outside passage ports  109  are opened to the outside and in each of the notched portions  132 , the lower pinch protrusion  87  of the pair of pinch protrusions  87  is exposed to the radial outside. 
   Also, the end (called a far end  140 , which is an example of a first end and is the front end in  FIG. 10  and is the lower end in  FIGS. 11 and 12 ) farthest from the outside passage ports  109  in the cover  126  located in the opened position is always in intimate contact with the outside peripheral wall  101  of the outside cabinet  82  over the width direction. Here, the cover seal  131  described above is disposed between the cover  126  and the outside peripheral wall  101 , so that the far end  140  is in intimate contact with the outside peripheral wall  101  without a gap. In contrast, the end (called a near end  141 , which is an example of a second end and is the back end in  FIG. 10  and is the upper end in  FIGS. 11 and 12 ) nearest to the outside passage ports  109  in the cover  126  located in the opened position is always separated from the outside peripheral wall  101  to the radial outside over the width direction when the cover  126  is in positions other than the closed position (including the time when the cover  126  is moving). 
   Here, when the cover  126  moves from the opened position (see  FIG. 11 ) to the closed position side (see  FIG. 12 ) and each of the engaging parts  128  of the cover  126  reaches the lower end of the corresponding guide rail  125 , each of the engaging parts  128  engages with the guide rail  125 . Then, in a state in which each of the engaging parts  128  engages with the guide rail  125 , the cover  126  is guided to the guide rail  125  and subsequently moves to the closed position side. At this time, each of the engaging parts  128  is fitted into the guide rail  125  which becomes deep as the guide rail  125  is located from the lower side (opened position side) toward the upper side (closed position side) as described above and accordingly, the near end  141  approaches the outside peripheral wall  101 . Then, as shown in  FIG. 12 , when the cover  126  moves to the closed position, each of the engaging parts  128  reaches the deepest part of the guide rail  125  and accordingly, the near end  141  of the cover  126  makes intimate contact with the outside peripheral wall  101 . Here, the cover seal  131  described above is disposed between the cover  126  and the outside peripheral wall  101 , so that the near end  141  is in intimate contact with the outside peripheral wall  101  without a gap. Also, as described above, the far end  140  is always in intimate contact with the outside peripheral wall  101 , and the cover  126  located in the closed position closes the outside passage ports  109  from the outside. 
   In contrast, when the cover  126  moves from the closed position to the opened position side, the near end  141  is separated from the outside peripheral wall  101  along the guide rail  125  which becomes shallow as the guide rail  125  is located from the closed position toward the opened position. 
   Also, a coil spring  139  as one example of a first urging member having two arm parts is wound on each of the boss parts  85 . In the coil spring  139 , one arm part is locked in the cartridge protrusion  121  and the other arm part is locked in the lever first protrusion  135  of each of the corresponding support levers  127 . Consequently, the cover unit  100  (specifically, the cover  126 ) is always urged toward the upper side (closed position). Also, the coil spring  138  described above always urges the cover  126  toward the circular arc center side, that is, the outside peripheral wall  101 . 
   (3) Attachment and Detachment of Developer Cartridge to and from Process Frame 
   (3-1) Attachment of Developer Cartridge to Process Frame 
   When the developer cartridge  31  is attached to the process frame  22 , the upper grasp plate  114  and the lower grasp plate  118  of the grip part  113  are first pinched in a direction in which their grasp plates move near as shown in  FIG. 7 . Then, the developer cartridge  31  (the inside cabinet  81  is arranged in a closed position and the cover  126  is in the closed position) is attached to the cartridge receiving part  33  (the shutter  68  is arranged in the closed position and the swing arm  70  is arranged in a pressing release position). 
   Concretely, each of the pressed protrusions  136  of the cover unit  100  first engages with the corresponding press recessed part  142  in the swing arm  70 . When the developer cartridge  31  is subsequently moved to the side of the cartridge receiving part  33  in this state, press force of a direction opposite to a movement direction (attachment direction) of the developer cartridge  31  is exerted on the pressed protrusion  136  from the swing arm  70  standing still in the pressing release position in the press recessed part  142 . Consequently, the cover  126  moves (falls) to the opened position side in a state in which the far end  140  is in intimate contact with the outside peripheral wall  101  against urging force of the coil spring  139  (see  FIG. 4 ). The near end  141  is separated from the outside peripheral wall  101  according to this movement. 
   Then, when each of the positioning bosses  106  is placed on each of the upper side fixed parts  66  and a pair of the pinch protrusions  87  of both sides of the width direction respectively pinch the upper edge and the lower edge of both ends of the width direction of the shutter  68  and each of the slide protrusions  86  is fitted into each of the receiving recessed parts  75  (see  FIG. 6 ), movement of the cover  126  to the opened position is completed (see  FIGS. 4 and 11 ). At this time, the far end  140  is in intimate contact with the outside peripheral wall  101  while the near end  141  is separated from the outside peripheral wall  101 , so that the cover  126  and the outside peripheral wall  101  are formed in substantially a 9 shape in the case of being viewed from the left side, and a recessed part  148  narrowing from the side of the near end  141  toward the far end  140  is formed between the cover  126  and the outside peripheral wall  101  (see  FIG. 4 ). 
   Thereafter, when the pinch of the grip part  113  is released, the locking claw  117  is locked in the lower side fixed part  67  and the developer cartridge  31  is received in the cartridge receiving part  33  as shown in  FIG. 4 . 
   The outside cabinet  82  is fixed to the cartridge receiving part  33  since the positioning bosses  106  are placed to the upper side fixed parts  66  and the locking claw  117  is locked to the lower side fixed part  67 . Consequently, attachment of the developer cartridge  31  to the process frame  22  is completed. 
   Then, the swing arm  70  is swung from the pressing release position to a pressing position. Then, each of the press protrusion parts  77  presses each of the pressed part  107  toward the back side as shown in  FIG. 5 . Consequently, the developer cartridge  31  is pressed toward the developing part  32 . Also, when the swing arm  70  is swung from the pressing release position to the pressing position, press force is exerted on the pressed protrusion  136  engaging with the press recessed part  142  from the swing arm  70  swung, and the cover  126  located in the opened position further moves in a position (called a retracted position) distant from the outside passage ports  109  (see  FIG. 3 ). In addition, the retracted position shall be included in the opened position. 
   Also, when the swing arm  70  is swung from the pressing release position to the pressing position, with swing of each of the arm side plates  72 , each of the slide protrusions  86  fitted into each of the receiving recessed parts  75  slides each of the slide holes  104  to the back side and is arranged in the back end of each of the slide holes  104 . Further, with the shutter  68  pinched, a pair of the pinch protrusions  87  of both sides of the width direction slide each of the elongated holes  108  to the lower side and are arranged in the lower end of each of the elongated holes  108 . 
   Consequently, as shown in  FIG. 3 , the inside cabinet  81  is arranged in the opened position and the inside passage ports  89  are opposed to the outside passage ports  109  and these passage ports are communicated. The shutter  68  is arranged in the opened position and the frame side passage ports  34  are opposed to the cartridge side passage ports  47  (the inside passage ports  89  and the outside passage ports  109 ) and these passage ports are communicated. 
   Then, when forming an image, by agitating the agitator  93 , the developer accommodated inside of the inside cabinet  81  is supplied from the inside supply port  90  and the outside supply port  110  (see  FIG. 10 ) to the side of the developing part  32  and is received inside the developing part  32  in the frame side supply port  60  (see  FIG. 8 ). 
   In contrast, according to the auger  35 , the developer supplied from the frame side supply port  60  to the inside of the developing part  32  is transported from the center of the width direction to both sides of the width direction and is supplied to the supply roller  36  on the way. The developer supplied to the supply roller  36  is supplied to the developing roller  37  as described above. The developer which has not been supplied to the supply roller  36  is transported to the frame side return ports  61  (see  FIG. 8 ) and passes through the outside return ports  111  and the inside return ports  91  (see  FIG. 10 ) and is returned from the developing part  32  to the inside of the inside cabinet  81 . Consequently, the developer is circulated between the developing part  32  and the inside cabinet  81 . 
   (3-2) Detachment of Developer Cartridge from Process Frame 
   When the developer cartridge  31  is detached from the process frame  22 , the swing arm  70  is first swung from the pressing position to the pressing release position. Then, each of the press protrusion parts  77  is separated from each of the pressed part  107  and a press of the developer cartridge  31  on the developing part  32  is released as shown in  FIG. 4 . Also, with this, the cover  126  located in the retracted position moves to the opened position with rotation of the inside cabinet  81 . 
   Also, when the swing arm  70  is swung from the pressing position to the pressing release position, with swing of each of the arm side plates  72 , each of the slide protrusions  86  fitted into each of the receiving recessed parts  75  slides each of the slide holes  104  to the front side and is arranged in the front end of each of the slide holes  104 . Further, with the shutter  68  pinched, a pair of the pinch protrusions  87  of both sides of the width direction slide each of the elongated holes  108  to the upper side and are arranged in the upper end of each of the elongated holes  108 . 
   Consequently, as shown in  FIG. 2 , the inside cabinet  81  is arranged in the closed position, and the upper side portion (see  FIG. 11 ) of the surrounded portion  88  is opposed to the outside passage ports  109 , and the outside passage ports  109  are closed. Also, the shutter  68  is arranged in the closed position, and the frame side passage ports  34  are opposed to the shutter  68  and are closed. 
   Then, when the upper grasp plate  114  and the lower grasp plate  118  of the grip part  113  are pinched in a direction in which their grasp plates move near, locking of the locking claw  117  to the lower side fixed part  67  is released, so that when the developer cartridge  31  is pulled from the cartridge receiving part  33  to the front side as it is, the developer cartridge  31  is detached from the process frame  22 . When the developer cartridge  31  is detached from the process frame  22 , engagement between the pressed protrusion  136  and the press recessed part  142  is released as shown in  FIGS. 4 and 7 , so that the cover  126  located in the opened position moves (rises) to the closed position by urging force of the coil spring  139 . In this movement, the near end  141  approaches the outside peripheral wall  101  and finally makes intimate contact with the outside peripheral wall  101 . Also, the far end  140  is always in intimate contact with the outside peripheral wall  101 . As a result of that, when the cover  126  moves to the closed position, the recessed part  148  between the cover  126  and the outside peripheral wall  101  described above gradually disappears (decreases) while an opening of the recessed part  148  moves upward. 
   In the developer cartridge  31 , as shown in  FIG. 2 , during movement of the cover  126  from the opened position to the closed position, the far end  140  of the cover  126  rises while being in intimate contact with the outside cabinet  82  and also, the near end  141  of the cover  126  rises in a state of being separated from the outside cabinet  82 . 
   As a result, even when the developer received inside of the outside cabinet  82  runs from the outside passage ports  109  to a surface of the outside of the outside cabinet  82  (specifically, the outside peripheral wall  101 ) and spills to the lower side, the developer enters between the cover  126  (specifically, the cover seal  131 ) and the outside cabinet  82  (specifically, the recessed part  148  described above) from the near end  141  and is accumulated in the far end  140 . Then, when the cover  126  rises to the closed position, the far end  140  rises while being in intimate contact with the outside cabinet  82  and finally, the outside passage ports  109  are covered with the cover  126  from the outside, so that while the developer spilling from the outside passage ports  109  is scooped up during closure of the outside passage ports  109  by the inside cabinet  81 , the developer is accumulated in the far end  140  and also the developer adhering to the vicinity of the outside passage ports  109  is covered from the outside and leakage of more developer can be prevented surely. 
   Further, as shown in  FIGS. 2 and 3 , the developer cartridge  31  can be formed in a double structure including the outside cabinet  82  and the inside cabinet  81 . Also, by opposing the outside passage ports  109  of the outside cabinet  82  to the inside passage ports  89  of the inside cabinet  81 , the developer can be moved to the inside and the outside of the outside cabinet  82  through the outside passage ports  109  and the inside passage ports  89  (see  FIG. 3 ). 
   Further, the inside cabinet  81  is a shutter which is rotatable with respect to the outside cabinet  82  and opens and closes the outside passage ports  109  according to the rotation of the inside cabinet  81 . 
   As a result, by rotating the inside cabinet  81  and opening the outside passage ports  109  and opposing the outside passage ports  109  to the inside passage ports  89 , the developer can be moved to the inside and the outside of the outside cabinet  82  through the outside passage ports  109  and the inside passage ports  89 . In contrast, movement of the developer to the inside and the outside of the outside cabinet  82  can be regulated by rotating the inside cabinet  81  and closing the outside passage ports  109  (see  FIG. 2 ). 
   Then, by disposing the cover  126  as described above, while the developer spilling from the outside passage ports  109  is scooped up during closure of the outside passage ports  109  by the inside cabinet  81 , the developer is accumulated in the far end  140  and also the developer adhering to the vicinity of the outside passage ports  109  is covered from the outside and thereby, leakage of more developer can be prevented surely. 
   Further, the near end  141  makes intimate contact with the outside cabinet  82  when the cover  126  moves in a closed position. 
   As a result, both of the near end  141  and the far end  140  of the cover  126  make intimate contact with the outside cabinet  82  when the cover  126  moves in the closed position, so that the outside passage ports  109  are sealed with the cover  126 . 
   As a result, leakage of the developer can be prevented more surely. 
   As shown in  FIG. 11 , the guide rail  125  for engaging with the cover  126  and guiding movement of the cover  126  is formed in the outside cabinet  82 , so that the cover  126  can be moved smoothly and surely between the closed position and the opened position by guiding the cover  126  to the guide rail  125 . 
   Further, the guide rail  125  becomes deep as the cover  126  is located from the opened position toward the closed position. As a result, when the cover  126  is in the opened position, the near end  141  is surely separated from the outside cabinet  82  and approaches the outside cabinet  82  as the cover  126  is located from the opened position toward the closed position and when the cover  126  is in the closed position, the near end  141  can surely be brought into intimate contact with the outside cabinet  82  (see  FIG. 12 ). 
   The cover seal  131  is disposed between the cover  126  and the outside cabinet  82  (specifically, the outside peripheral wall  101 ), so that the far end  140  is surely brought into intimate contact with the outside cabinet  82  and when the cover  126  is in the closed position, the near end  141  is surely brought into intimate contact with the outside cabinet  82  and the outside passage ports  109  can be sealed with the cover  126  (see  FIG. 12 ). 
   As shown in  FIG. 12 , the developer cartridge  31  includes the coil spring  139  for urging the cover  126  toward the closed position, so that the outside passage ports  109  are closed by the cover  126  in a normal state. 
   The developer cartridge  31  includes the coil spring  138  for urging the cover  126  toward the outside cabinet  82 . As a result, the near end  141  of the cover  126  can surely be brought into intimate contact with the outside cabinet  82  when the cover  126  is in the closed position. 
   As a result of that, leakage of the developer can be prevented surely. 
   As shown in  FIG. 10 , the outside passage ports  109  are formed in the outside peripheral wall  101  of the outside cabinet  82  and as shown in  FIG. 12 , the guide rails  125  are formed in both ends of the width direction of the outside passage ports  109  in the outside cabinet  82 , and the cover  126  includes the engaging parts  128  for engaging with the guide rails  125  in both ends of the width direction. 
   Consequently, the portion of engagement between the cover  126  and the guide rails  125  is not arranged inside the outside passage ports  109 , so that smooth movement of the cover  126  and smooth movement of the developer in the outside passage ports  109  can be ensured. 
   Also, as shown in  FIGS. 10 ,  11  and  12 , the cover  126  is rotatably supported in the inside cabinet  81  and the outside cabinet  82  around a line through the rotation shaft of the inside cabinet  81 . Consequently, by matching the rotation center of the cover  126  with the rotation center of the inside cabinet  81 , the developer cartridge  31  can be constructed simpler than the case of separately forming these centers. 
   Also, as shown in  FIG. 2 , the developer cartridge  31  is detachably attached to the process frame  22  of the developing device  17 , so that the developing device  17  can be newly replenished with the developer by replacing the developer cartridge  31 . 
   Then, as shown in  FIG. 4 , the developer cartridge  31  includes the pressed protrusion  136 . The pressed protrusion  136  moves the cover  126  from the closed position to the opened position according to attachment of the developer cartridge  31  to the process frame  22 . As a result, by only attaching the developer cartridge  31  to the process frame  22 , the cover  126  can be moved to the opened position to open the outside passage ports  109 , so that operability can be improved. 
   Also, the pressed protrusion  136  can surely move the cover  126  from the closed position to the opened position according to attachment of the developer cartridge  31  to the process frame  22  by simple construction of being pressed on the swing arm  70  disposed in the process frame  22 . 
   MODIFIED EXAMPLES 
   In the above-described aspects, the developing device  17  integrally includes the photoconductive drum  25  and the developing roller  37 , and the developing device  17  is detachably attached to the body casing  2 . Additionally, while a developing cartridge without including the photoconductive drum  25  is used as the developing device  17 , another unit (i.e., drum cartridge) including the photoconductive drum  25  may be disposed and the developing cartridge may be detachably attached to the drum cartridge. 
   Further, the photoconductive drum  25 , the scorotron-type charger  26  and the transfer roller  28  can also be disposed in the body casing  2  to detachably attach the developing cartridge to the body casing  2 . 
   Still further, the developer cartridge  31  may singly be detachably attached to the body casing  2 . In that case, the developing device  17  (that is, the process frame  22 ) to which the developer cartridge  31  is not attached can be attached to and detached from the body casing  2 , and the developer cartridge  31  is attached to and detached from the process frame  22  attached to the body casing  2 . 
   Still further, although aspects of the present inventive concept have been described in relation to a laser printer, the present inventive concept is not limited to a monochrome laser printer. Rather, the present inventive concept can also be applied to a color laser printer, including a tandem type and an intermediate transfer type printer. 
   Still further, in the above-described aspects, the inside cabinet  81  is rotatable with respect to the outside cabinet  82 . However, the outside cabinet  82  may be rotatable with respect to the inside cabinet  81 , and the outside cabinet  82  may form a shutter. Additionally, by disposing the cover  126 , while the developer spilling from the outside passage ports  109  is scooped up during a closure action of the outside cabinet  82 , the developer is accumulated in the far end  140  and also the developer adhering to the vicinity of the outside passage ports  109  is covered from the outside and thereby, leakage of more developer can be prevented surely.