Patent Publication Number: US-11656574-B2

Title: Image forming apparatus

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation Application of U.S. patent application Ser. No. 17/407,444, filed Aug. 20, 2021, which is a Continuation Application of U.S. patent application Ser. No. 16/907,599, filed Jun. 22, 2020, now U.S. Pat. No. 11,156,599 issued Oct. 26, 2021, and claims priority from Japanese Patent Application No. 2019-123951 filed on Jul. 2, 2019, the entireties of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     The following disclosure relates to an image forming apparatus. 
     There has been known an electrophotographic image forming apparatus in which a process cartridge including a photoconductive drum and a toner container is removably mounted to a drawer. The image forming apparatus of this type requires replacement of the process cartridge when the toner container becomes empty of toner. However, the photoconductive drum has not reached the end of its useful life at this time, and thus the photoconductive drum is discarded before the end of the useful life, resulting in increase in running costs. 
     To solve this problem, an image forming apparatus is devised in which the process cartridge is separated into a drum cartridge including the photoconductive drum and a toner cartridge including the toner container to enable individual replacement of the drum cartridge and the toner cartridge. 
     In such an image forming apparatus, unfortunately, the drum cartridge is mounted to the drawer, and the toner cartridge is mounted to the drum cartridge, but the toner cartridge moves relative to the drawer in removal of the toner cartridge from the drum cartridge, making it difficult to remove the toner cartridge. 
     SUMMARY 
     Accordingly, an aspect of the disclosure relates to an image forming apparatus capable of making a drum cartridge immovable relative to a drawer when a toner cartridge is removed from the drum cartridge mounted to the drawer. 
     In one aspect of the disclosure, an image forming apparatus includes: a housing; a process cartridge including a photoconductive drum and a developing roller; a toner cartridge containing toner; and a drawer movable between an inner position and an outer position, the process cartridge being located in the housing when the drawer is located at the inner position in a state in which the process cartridge is mounted to the drawer, at least a portion of the process cartridge being exposed to an outside of the housing when the drawer is located at the outer position in the state in which the process cartridge is mounted to the drawer. The process cartridge includes a lock member movable between a lock position at which the lock member locks the process cartridge to the drawer in the state in which the process cartridge is mounted to the drawer, and a release position at which a lock between the process cartridge and the drawer is released. The lock member is located at the lock position in a state in which the process cartridge is mounted to the drawer, and the toner cartridge is mounted to the process cartridge. The lock member is located at the release position in a state in which the process cartridge is mounted to the drawer, and the toner cartridge is removed from the process cartridge. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The objects, features, advantages, and technical and industrial significance of the present disclosure will be better understood by reading the following detailed description of the embodiment, when considered in connection with the accompanying drawings, in which: 
         FIG.  1    is a central cross-sectional view of an image forming apparatus; 
         FIG.  2    is a side elevational view in cross section, illustrating the image forming apparatus in a state in which drawer guides are located at their respective positioning positions, and a drawer is located at an inner position; 
         FIG.  3    is a cross-sectional view taken along line A-A in  FIG.  2   ; 
         FIG.  4    is a side elevational view in cross section, illustrating the image forming apparatus in a state in which the drawer guides are located at their respective positioning cancel positions, and the drawer is located at an outer position; 
         FIG.  5 A  is a front elevational view of a toner cartridge; 
         FIG.  5 B  is a side view of the toner cartridge; 
         FIG.  6    is an elevational cross-sectional view of the toner cartridge; 
         FIG.  7 A  is a partial side elevational view in cross section, illustrating the toner cartridge with a first shutter being closed; 
         FIG.  7 B  is a partial side elevational view in cross section, illustrating the toner cartridge with the first shutter being open; 
         FIG.  8 A  is a perspective view of the toner cartridge, with the first shutter being closed; 
         FIG.  8 B  is a perspective view of the toner cartridge, with the first shutter being open; 
         FIG.  9 A  is a side elevational view in cross section, illustrating a process cartridge; 
         FIG.  9 B  is a side view of the process cartridge; 
         FIG.  10    is a cross-sectional view taken along line B-B in  FIG.  9 A ; 
         FIG.  11    is a cross-sectional view taken along line C-C in  FIG.  9 B ; 
         FIG.  12 A  is a perspective view of the process cartridge, with a second shutter being closed; 
         FIG.  12 B  is a perspective view of the process cartridge, with the second shutter being open; 
         FIG.  13    is an elevational cross-sectional view of a process unit in a state in which the toner cartridge is mounted to the process cartridge, and a lock member is located at a lock position; 
         FIG.  14    is a perspective view illustrating a situation in which a first projecting portion is fitted into a first recessed portion, and a second projecting portion is fitted into a second recessed portion when the toner cartridge is mounted to the process cartridge; 
         FIG.  15 A  is a side elevational view in cross section, illustrating a state in which the toner cartridge mounted to the process cartridge is located at a first position; and 
         FIG.  15 B  is a side elevational view in cross section, illustrating a state in which the toner cartridge mounted to the process cartridge is located at a second position. 
     
    
    
     EMBODIMENT 
     Hereinafter, there will be described one embodiment by reference to the drawings. It is to be understood that the following embodiment is described only by way of example, and the disclosure may be otherwise embodied with various modifications without departing from the scope and spirit of the disclosure. 
     Overall Configuration of Image Forming Apparatus 
       FIG.  1    illustrates an image forming apparatus  1  according to one embodiment of the present disclosure. The image forming apparatus  1  is an electrophotographic tandem color printer configured to form an image on a sheet S in multiple colors. 
     In the following description, the left side in  FIG.  1    is defined as a front side of the image forming apparatus  1 , the right side in  FIG.  1    as a rear side of the image forming apparatus  1 , the front side of the sheet of  FIG.  1    as a right side of the image forming apparatus  1 , and the back side of the sheet of  FIG.  1    as a left side of the image forming apparatus  1 . The upper side and the lower side in  FIG.  1    are defined as an upper side and a lower side of the image forming apparatus  1 , respectively. 
     The image forming apparatus  1  includes: a housing  2 ; a sheet-supply tray  10  capable of supporting the sheet S; and an image forming device  5  configured to form an image on the sheet S. 
     The housing  2  has a substantially rectangular parallelepiped shape and houses the sheet-supply tray  10  and the image forming device  5 . A front surface  21  of the housing  2  has an opening  2 A. The housing  2  includes a front-surface cover  22  capable of exposing and closing the opening  2 A. 
     A pivot shaft  22   a  is provided at a lower end portion of the front-surface cover  22 . The front-surface cover  22  is pivotable about the pivot shaft  22   a . The opening  2 A is exposed and closed by pivotal movement of the front-surface cover  22  about the pivot shaft  22   a . A sheet-discharge tray  23   a  is provided on an upper surface  23  of the housing  2 . The sheet-discharge tray  23   a  is inclined so as to be lower at its rear portion than its front portion. 
     A conveyance path P for the sheet S is formed in the housing  2  so as to extend from the sheet-supply tray  10  to the sheet-discharge tray  23   a  via the image forming device  5 . Sheet-supply rollers  11 , separating rollers  12 , and a separator pad  12   a  are provided in the housing  2 . The sheets S supported on the sheet-supply tray  10  are separated into one and the other by the sheet-supply rollers  11 , the separating rollers  12 , and the separator pad  12   a  and supplied one by one into the conveyance path P. 
     The image forming device  5  is disposed over the sheet-supply tray  10  and includes four process units  50  arranged side by side in the front and rear direction. The process units  50  are mountable and removable on and from the housing  2  and provided so as to correspond respectively to black, yellow, magenta, and cyan. 
     The housing  2  includes a drawer  60  that supports the process units  50 . Each of the process units  50  includes a process cartridge  51  and a toner cartridge  52 . The process cartridge  51  is removably mounted on the drawer  60 . The toner cartridge  52  is removably mounted on the process cartridge  51 . 
     The process cartridge  51  includes a photoconductive drum  54 , an electrically charged roller  58 , and a developing unit  59 . The photoconductive drum  54  has a substantially cylindrical shape with its axial direction coinciding with the right and left direction. The photoconductive drum  54  is rotatably supported by the process cartridge  51 . The electrically charged roller  58  extends in the right and left direction and is held in contact with an upper front portion of the photoconductive drum  54 . 
     The developing unit  59  includes a developing roller  55 , a supply roller  56 , and a unit frame  591  supported by the process cartridge  51 . The developing roller  55  extends in the right and left direction and is rotatably supported by the unit frame  591 . The developing roller  55  is held in contact with an upper rear portion of the photoconductive drum  54 . The supply roller  56  extends in the right and left direction and is rotatably supported by the unit frame  591 . The supply roller  56  is held in contact with an upper rear portion of the developing roller  55 . 
     The toner cartridge  52  includes a toner container  57  containing toner as a developer. The toner container  57  is disposed above the developing unit  59 . The toner is supplied from the toner container  57  to the supply roller  56 . The supply roller  56  supplies the toner to the developing roller  55 . The developing roller  55  supplies the toner to the photoconductive drum  54 . 
     An exposing unit  53  is provided over the process units  50  to expose surfaces of the respective photoconductive drums  54 . 
     An intermediate transfer belt  31  is provided under the photoconductive drums  54  so as to be opposed to the photoconductive drums  54 . The intermediate transfer belt  31  is tensioned between a driven roller  32  and a drive roller  33  located in front of the driven roller  32 . Primary transfer rollers  34  are opposed to the respective photoconductive drums  54 , with the intermediate transfer belt  31  interposed between each of the primary transfer rollers  34  and a corresponding one of the photoconductive drums  54 . 
     A second transfer roller  35  is held in contact with the driven roller  32 , with the intermediate transfer belt  31  interposed therebetween. A belt unit  30  is constituted by the intermediate transfer belt  31 , the driven roller  32 , the drive roller  33 , the primary transfer rollers  34 , and the second transfer roller  35 . 
     In the image forming device  5 , the surface of the photoconductive drum  54  is uniformly charged by the electrically charged roller  58 , and then selectively exposed by the exposing unit  53  based on predetermined image data. As a result, an electrostatic latent image based on the image data is formed on the surface of the photoconductive drum  54 . 
     The toner contained in the toner container  57  is positively charged between the supply roller  56  and the developing roller  55  and born on a surface of the developing roller  55 . The toner born on the developing roller  55  is supplied to the electrostatic latent image formed on the surface of the photoconductive drum  54 , a toner image is born on the surface of the photoconductive drum  54 . 
     The toner image born on the surface of the photoconductive drum  54  is primarily transferred to the intermediate transfer belt  31  by a transfer bias applied to the primary transfer roller  34 . The toner images born on the respective photoconductive drums  54  are superposed on the intermediate transfer belt  31 . 
     The sheet S supplied from the sheet-supply tray  10  to the conveyance path P is conveyed rearward by a plurality of conveying rollers  13  and supplied to a nipping position between the intermediate transfer belt  31  and the second transfer roller  35 . The sheet S supplied to the nipping position is conveyed while being nipped between the intermediate transfer belt  31  and the second transfer roller  35 . 
     A secondary transfer bias is applied to the second transfer roller  35 . The polarity of the secondary transfer bias is opposite to that of electric charges on the toner images formed on the intermediate transfer belt  31 . Thus, the toner images on the intermediate transfer belt  31  are secondarily transferred to the sheet S in a process in which the sheet S is conveyed between the intermediate transfer belt  31  and the second transfer roller  35 . 
     In the present embodiment, the intermediate transfer belt  31  is configured such that the toner images are primarily transferred from the respective photoconductive drums  54  to the intermediate transfer belt  31 , and the toner images primarily transferred are secondarily transferred to the sheet S. However, the intermediate transfer belt  31  may be replaced with a conveyor belt configured to convey the sheet S to which the toner images are transferred from the respective photoconductive drums  54 . 
     The sheet S to which the toner images have been transferred is conveyed to a fixing device  16  disposed downstream of the image forming device  5 . The fixing device  16  includes a heat roller  17  and a pressure roller  18  held in pressing contact with the heat roller  17 . The toner images are thermally fixed to the sheet S conveyed to the fixing device  16 , while the sheet S is passing through a position between the heat roller  17  and the pressure roller  18 . 
     The sheet S to which the toner images are thermally fixed is conveyed downstream from the fixing device  16  in the conveying direction and discharged onto the sheet-discharge tray  23   a  by a sheet-discharge roller  19 . 
     Structure for Process Unit and Drawer 
     As illustrated in  FIGS.  2  and  3   , the drawer  60  is a substantially rectangular frame member capable of supporting the four process units  50 . The drawer  60  includes a pair of side frames  61  arranged respectively on right and left sides of the process units  50  and each extending in the front and rear direction. Each of the side frames  61  includes four support grooves  62  arranged in the front and rear direction and each extending substantially in the up and down direction. An upper end of the support groove  62  is open. The number of the support grooves  62  corresponds to the number of the process units  50 . 
     The process cartridge  51  of each of the process units  50  includes a pair of right and left cartridge frames  511  supporting a corresponding one of the photoconductive drums  54 . The photoconductive drum  54  includes a drum body  54   a  and drum shafts  54   b  each protruding from the drum body  54   a  outward in the right and left direction. The cartridge frames  511  support the respective right and left drum shafts  54   b  rotatably. The drum shafts  54   b  are end portions of the photoconductive drum  54  in the axial direction, respectively. 
     Each of the cartridge frames  511  includes a side wall  511   a  extending in the up and down direction and a protruding portion  511   b  protruding from the side wall  511   a  outward in the right and left direction. One of the pair of the side wall  511   a  and the protruding portion  511   b  is disposed to the right of the photoconductive drum  54 , and the other is disposed to the left of the photoconductive drum  54 . A portion of the side wall  511   a  at which the protruding portion  511   b  is formed has a support hole  512  for supporting the drum shaft  54   b  rotatably. 
     The developing roller  55  includes right and left roller shafts  55   a . Each of the roller shafts  55   a  protrudes outward from the unit frame  591  in the right and left direction. The side wall  511   a  has a guide hole  511   c  in which a corresponding one of the roller shafts  55   a  is inserted. The guide hole  511   c  is elongated such that the roller shaft  55   a  is slidable along the major axis direction of the guide hole  511   c.    
     The protruding portion  511   b  of the process cartridge  51  is insertable into the support groove  62  of the side frame  61  from above. When the protruding portions  511   b  of the process cartridge  51  are inserted in the respective support grooves  62 , the process unit  50  is mounted to the drawer  60 . 
     The housing  2  includes vertical frames  24  each extending in the front and rear direction and the up and down direction. The vertical frames  24  are disposed respectively at right and left end portions of the housing  2  in the housing  2 . Each of the vertical frames  24  has two guide holes  24   a . Each of the guide holes  24   a  is an elongated hole extending substantially in the front and rear direction and inclined so as to be higher at its front portion than at its rear portion. The two guide holes  24   a  are located apart from each other in the front and rear direction. 
     A pair of right and left drawer guides  65  are provided in the housing  2  each on an inner side of a corresponding one of the vertical frames  24  in the right and left direction. Each of the drawer guides  65  is a rail member extending in the front and rear direction. The side frames  61  of the drawer  60  are supported on the respective drawer guides  65  so as to be movable in the front and rear direction. 
     The drawer guides  65  respectively include guide pins  65   a  each extending outward in the right and left direction. The guide pins  65   a  are provided so as to correspond to the respective guide holes  24   a  and slidably inserted in the respective guide holes  24   a . Since the guide pins  65   a  are inserted in the respective guide holes  24   a , the drawer guides  65  are supported by the respective vertical frames  24 . Each of the drawer guides  65  are movable in the front and rear direction and the up and down direction relative to a corresponding one of the vertical frames  24  within a region in which the guide pins  65   a  are slidable in the respective guide holes  24   a.    
     Engaging pins  65   b  each protruding outward in the right and left direction are provided on front end portions of the respective drawer guides  65 . The front-surface cover  22  of the housing  2  includes link arms  27 . Each of the link arms  27  has an arc shape curved rearward and downward from the front-surface cover  22 . The link arms  27  respectively have engaging holes  27   a  engageable with the respective engaging pins  65   a . Each of the engaging holes  27   a  has an arc shape curved so as to be lower at its rear portion than at its front portion. 
     With this configuration, the drawer  60  is movable between an inner position (illustrated in  FIG.  2   ) and an outer position (illustrated in  FIG.  4   ) in the front and rear direction. That is, the moving direction of the drawer  60  coincides with the front and rear direction, and a side nearer to the outer position than to the inner position in the moving direction of the drawer  60  is a front side, and a side nearer to the inner position than to the outer position in the moving direction of the drawer  60  is a rear side. 
     As illustrated in  FIG.  2   , when the drawer  60  is located at the inner position in the state in which the process cartridge  51  is mounted to the drawer  60 , the process cartridge  51  and the toner cartridge  52  are contained in the housing  2 . 
     As illustrated in  FIG.  4   , when the drawer  60  is located at the outer position in the state in which the process cartridge  51  is mounted to the drawer  60 , at least a portion of the process cartridge  51  and the toner cartridge  52  is exposed to the outside of the housing  2 . When the drawer  60  is located at the outer position, the process cartridge  51  and the toner cartridge  52  exposed to the outside of the housing  2  are mountable on and removable from the drawer  60 . 
     The drawer guides  65  are movable in the front and rear direction between (i) their respective positioning positions (illustrated in  FIG.  2   ) at which the process cartridges  51  are positioned with respect to the housing  2  and (ii) their respective positioning cancel positions (illustrated in  FIG.  4   ) at which the positioning of the process cartridges  51  with respect to the housing  2  is canceled, and the drawer  60  is movable in the front and rear direction. 
     As illustrated in  FIG.  2   , when the front-surface cover  22  of the housing  2  is closed, the drawer  60  is located at the inner position, and the drawer guides  65  are located at their respective positioning positions. When the drawer guides  65  are located at their respective positioning positions, the guide pins  65   a  are located at rear end portions of the respective guide holes  24   a . Thus, each of the drawer guides  65  is located at a rear and lower portion of its movable region. 
     The housing  2  includes a horizontal frame  25  extending in the horizontal direction between the right and left vertical frames  24 . The horizontal frame  25  is disposed below the drawer guides  65 . A pair of right and left support plates  26  are provided upright on the horizontal frame  25 . Each of the support plates  26  is a plate member extending in the front and rear direction. Each of the support plates  26  is disposed on an inner side of a corresponding one of the side frames  61  of the drawer  60  in the right and left direction. 
     An upper end of each of the support plates  26  has positioning recessed portions  26   a  formed respectively at positions corresponding to the positions of the respective process cartridges  51  in the front and rear direction. When the drawer guides  65  are located at their respective positioning positions, the cartridge frames  511  of the process cartridge  51  are supported by the respective positioning recessed portions  26   a  from below. This configuration positions the process cartridges  51  with respect to the housing  2 . 
     It is noted that the right and left support plates  26  are sheet-metal members formed by press working using the same metal mold and having the same shape. This makes it possible to reduce positional misalignment of the photoconductive drums  54  when the process cartridges  51  are positioned. 
     Thus, when the drawer guides  65  are located at their respective positioning positions, the process cartridges  51  are supported by the support plates  26 , thereby positioning the process cartridges  51  with respect to the housing  2 . 
     When the front-surface cover  22  of the housing  2  is opened in the state illustrated in  FIG.  2   , as illustrated in  FIG.  4   , the link arms  27  are moved frontward, causing the engaging pins  65   b  to be engaged with rear edges of the respective engaging holes  27   a , whereby the drawer guides  65  are pulled frontward. The drawer guides  65  pulled frontward are moved frontward to their respective positioning cancel positions. 
     In this case, since the guide pins  65   a  are slid from the rear end portions to the front end portions of the respective guide holes  24   a  with frontward movement of the drawer guides  65 , the drawer guides  65  are also moved upward. 
     When the drawer guides  65  are moved frontward and upward, the drawer  60  supported by the drawer guides  65  are moved upward with the process cartridges  51 . This moves the process cartridges  51  upward away from the support plates  26 , thereby canceling the state in which the process cartridges  51  are supported by the support plates  26 . 
     With the frontward and upward movement of the drawer guides  65 , the drawer  60  moves upward straightly without moving frontward. The process cartridges  51  supported by the drawer  60  are also moves upward straightly. This prevents the photoconductive drums  54  supported by the respective process cartridge  51  from rubbing against the intermediate transfer belt  31  in the front and rear direction, resulting in less damage to the photoconductive drums  54  and the intermediate transfer belt  31 . 
     Thus, when the drawer guides  65  are located at their respective positioning cancel positions, the state in which the process cartridges  51  are supported by the support plates  26  is canceled. This cancels the positioning of the process cartridges  51  with respect to the housing  2 , making the drawer  60  movable in the front and rear direction. 
     When the front-surface cover  22  is opened, the drawer  60  becomes movable in the front and rear direction. The user in this state can grasp a handle  64  of the drawer  60  located at the inner position (see the drawer  60  indicated by the two-dot chain lines in  FIG.  4   ) and pull the drawer  60  frontward to move the drawer  60  to the outer position (see the drawer  60  indicated by the solid lines in  FIG.  4   ). 
     In the state in which the drawer  60  is located at the outer position, the process cartridges  51  and the toner cartridges  52  of the process units  50  exposed to the outside of the housing  2  are mountable to and removable from the drawer  60 . 
     The drawer  60  can be moved to the inner position by pressing the drawer  60  located at the outer position, rearward. When the front-surface cover  22  is closed in the state in which the drawer guides  65  are located at their respective positioning cancel positions as a result of opening of the front-surface cover  22 , the engaging pins  65   b  are engaged with front edges of the respective engaging holes  27   a , whereby the drawer guides  65  are pressed rearward. When the drawer guides  65  are pressed rearward, the drawer guides  65  are moved rearward to their respective positioning positions. 
     Toner Cartridge 
     As illustrated in  FIGS.  5  and  6   , each of the toner cartridges  52  includes a toner frame  521  formed with the toner container  57 . A handle  521   a  is formed at an upper end portion of the toner frame  521 . The user is allowed to grasp the handle  521   a  when removing the toner cartridge  52  from the process cartridge  51 . 
     A toner supplier  522  is formed below the toner container  57  in the toner frame  521 . The toner supplier  522  is for supplying the toner stored in the toner container  57 , to the supply roller  56 . 
     The toner supplier  522  communicates at its right and left end portions with the toner container  57  respectively via communicating holes  57   a  so as to allow the toner stored in the toner container  57  to flow into the toner supplier  522  via the communicating holes  57   a . A screw  523  is provided in the toner supplier  522 . The screw  523  is disposed such that its axis direction coincides with the right and left direction and is configured such that the toner having flowed in the right and left end portions of the toner supplier  522  via the respective communicating holes  57   a  is transferred toward the center of the toner supplier  522  in the right and left direction. 
     A lower portion of the toner supplier  522  has an arc shape protruding downward in side view. A lower end portion of a central portion of the toner supplier  522  in the right and left direction has a supply hole  522   a  through which the toner supplied from the toner container  57  is allowed to pass. The supply hole  522   a  is elongated with its longitudinal direction coinciding with the right and left direction. 
     The toner cartridge  52  includes a first shutter  524  capable of exposing and closing the supply hole  522   a . The first shutter  524  is disposed at the central portion of the toner supplier  522  in the right and left direction. The first shutter  524  is a substantially cylindrical member mounted around the toner supplier  522  such that the axis direction of the first shutter  524  coincides with the right and left direction. The first shutter  524  has a communication opening  524   a  that is an elongated hole with its longitudinal direction coinciding with the right and left direction. The communication opening  524   a  has a size corresponding to the size of the supply hole  522   a.    
     First projecting portions  524   b  (each as one example of a third engaging portion) are formed on the first shutter  524  respectively at positions each located on an outer side of the supply hole  522   a  in the right and left direction. Each of the first projecting portions  524   b  protrudes downward. As illustrated in  FIG.  5 B , positions at which the first projecting portions  524   b  are formed on the first shutter  524  and a position at which the communication opening  524   a  is formed in the first shutter  524  are different from each other in the circumferential direction. The communication opening  524   a  is formed on a front side of the first projecting portions  524   b  in the circumferential direction. 
     Second projecting portions  525  (each one example of a fifth engaging portion) are formed on a lower end of the toner supplier  522  respectively at positions each located on an outer side of the first shutter  524  in the right and left direction. Each of the second projecting portions  525  protrudes downward. Positions at which the second projecting portions  525  are formed on the toner supplier  522  and a position at which the supply hole  522   a  is formed in the toner supplier  522  are the same as each other in the circumferential direction. Guide projecting portions  526  are formed respectively on right and left end portions of the toner supplier  522  so as to each protrude outward in the right and left direction. Each of the guide projecting portions  526  has a rectangular shape, with its longitudinal direction coincides with the up and down direction in side view. 
     The first shutter  524  is capable of exposing and closing the supply hole  522   a  of the toner supplier  522  by pivoting about the axis of the first shutter  524  relative to the toner supplier  522  of the toner frame  521 . 
     For example, as illustrated in  FIGS.  7 A and  8 A , when the pivot position of the first shutter  524  is located at a position at which the supply hole  522   a  of the toner supplier  522  and the communication opening  524   a  of the first shutter  524  are different from each other in phase in the circumferential direction, the supply hole  522   a  is covered with the first shutter  524 . 
     The state in which the supply hole  522   a  is covered with the first shutter  524  is a state in which the first shutter  524  is closed. In this case, the first projecting portions  524   b  of the first shutter  524  and the second projecting portions  525  of the toner supplier  522  are the same as each other in phase in the circumferential direction. 
     As illustrated in  FIGS.  7 B and  8 B , when the pivot position of the first shutter  524  is located at a position at which the supply hole  522   a  of the toner supplier  522  and the communication opening  524   a  of the first shutter  524  are the same as each other in phase in the circumferential direction, the supply hole  522   a  and the communication opening  524   a  communicate with each other, establishing a state in which the supply hole  522   a  is exposed by (not covered with) the first shutter  524 . 
     The state in which the supply hole  522   a  is exposed by the first shutter  524  is a state in which the first shutter  524  is open. In this case, the first projecting portions  524   b  of the first shutter  524  are different from the second projecting portions  525  of the toner supplier  522  in phase in the circumferential direction, and the first projecting portions  524   b  are located on a rear side of the second projecting portions  525 . 
     Thus, the supply hole  522   a  can be exposed and closed by the first shutter  524  in the toner cartridge  52  by causing pivotal movement of the first shutter  524  relative to the toner supplier  522  to move the first shutter  524  and the toner supplier  522  relative to each other. 
     Process Cartridge 
     (Toner-Cartridge Supporter) 
     As illustrated in  FIGS.  9 A- 13   , the cartridge frames  511  of each of the process cartridges  51  respectively include a toner-cartridge supporter  514  extending in the right and left direction from one of the right and left side walls  511   a  to the other therebetween. The toner-cartridge supporter  514  includes support surface portions  514   a  and an open/close surface portion  514   b . The support surface portions  514   a  are arranged respectively at right and left portions of the toner-cartridge supporter  514  to support the toner cartridge  52  mounted to the process cartridge  51 . The open/close surface portion  514   b  is disposed between the right and left support surface portions  514   a.    
     Each of the support surface portions  514   a  has an arc shape protruding downward in side view, and this shape corresponds to the shape of the lower portion of the toner supplier  522  of the toner frame  521 . The open/close surface portion  514   b  has an arc shape protruding downward in side view. The arc shape of the open/close surface portion  514   b  is greater in diameter than the arc shape of each of the support surface portions  514   a.    
     The open/close surface portion  514   b  has a supplied hole  514   c  elongated with its longitudinal direction coinciding with the right and left direction. The supplied hole  514   c  has a size corresponding to the size of the supply hole  522   a  of the toner supplier  522 . First recessed portions  514   d  (each as one example of a fourth engaging portion) are formed respectively on outer sides of the supplied hole  514   c  of the open/close surface portion  514   b  in the right and left direction. 
     The first projecting portions  524   b  of the first shutter  524  are fitted in the respective first recessed portions  514   d  when the toner cartridge  52  is mounted to the process cartridge  51 . Each of the first recessed portions  514   d  has a size and a shape corresponding to those of a corresponding one of the first projecting portions  524   b . Positions at which the first recessed portions  514   d  are formed on the open/close surface portion  514   b  and a position at which the supplied hole  514   c  is formed are different from each other in the circumferential direction. The supplied hole  514   c  is formed on a front side of the first recessed portions  514   d  in the circumferential direction. It is noted that the first projecting portions  524   b  and the first recessed portions  514   d  at least need to be configured to be engaged respectively with each other. For example, the image forming apparatus  1  may be configured such that recessed portions are formed in the first shutter  524 , and projecting portions are formed on the toner-cartridge supporter  514 . 
     A second shutter  515  is provided on and between the cartridge frames  511  to expose and close the supplied hole  514   c  of the toner-cartridge supporter  514 . The second shutter  515  is disposed over the open/close surface portion  514   b . The second shutter  515  has an arc shape protruding downward in side view. Right and left end portions of the second shutter  515  are supported by the support surface portions  514   a  so as to be slidable in the circumferential direction. This configuration enables the second shutter  515  to slide with respect to the open/close surface portion  514   b  in the circumferential direction. 
     The second shutter  515  has a communication opening  515   a  elongated with its longitudinal direction coinciding with the right and left direction. The communication opening  515   a  has a size corresponding to the size of the supply hole  522   a  of the toner supplier  522 . Second recessed portions  515   b  (each one example of a sixth engaging portion) are formed on the second shutter  515  at positions each located on an outer side of the communication opening  515   a  in the right and left direction. 
     The second projecting portions  525  of the toner cartridge  52  are fitted in the respective second recessed portions  515   b  when the toner cartridge  52  is mounted to the process cartridge  51 . Each of the second recessed portions  515   b  has a size and a shape corresponding to those of a corresponding one of the second projecting portions  525 . Positions at which the second recessed portions  515   b  are formed on the second shutter  515  and a position at which the communication opening  515   a  is formed in the second shutter  515  are the same as each other in the circumferential direction. 
     The second shutter  515  has insertion holes  515   c  each formed between the communication opening  515   a  and a corresponding one of the second recessed portions  515   b  in the right and left direction. Each of the insertion holes  515   c  is elongated in the circumferential direction. The first projecting portions  524   b  of the first shutter  524  are insertable into the respective insertion holes  515   c.    
     The insertion holes  515   c  are positioned with respect to the first recessed portions  514   d  of the open/close surface portion  514   b , allowing the first projecting portions  524   b  to be fitted in the respective first recessed portions  514   d  in the state in which the first projecting portions  524   b  are inserted in the respective insertion holes  515   c . The length of each of the insertion holes  515   c  in the circumferential direction is greater than that of a corresponding one of the first projecting portions  524   b , allowing the second shutter  515  to slide in the circumferential direction in a state in which the first projecting portions  524   b  are inserted in the respective insertion holes  515   c  and fitted in the respective first recessed portions  514   d.    
     The second shutter  515  exposes and closes the supplied hole  514   c  of the toner-cartridge supporter  514  by sliding with respect to the toner-cartridge supporter  514  in the circumferential direction. 
     For example, as illustrated in  FIG.  12 A , when the pivot position of the second shutter  515  is located at a position at which the supplied hole  514   c  of the toner-cartridge supporter  514  is different from the communication opening  515   a  of the second shutter  515  in phase in the circumferential direction, the supplied hole  514   c  is covered with the second shutter  515 . 
     The state in which the supplied hole  514   c  is covered with the second shutter  515  is a state in which the second shutter  515  is closed. In this case, the first recessed portions  514   d  of the toner-cartridge supporter  514  and the second recessed portions  515   b  of the second shutter  515  are the same in phase in the circumferential direction. 
     As illustrated in  FIG.  12 B , when the pivot position of the second shutter  515  is located at a position at which the supplied hole  514   c  of the toner-cartridge supporter  514  is the same as the communication opening  515   a  of the second shutter  515  in phase in the circumferential direction, the supplied hole  514   c  and the communication opening  515   a  communicate with each other, establishing a state in which the supplied hole  514   c  is exposed by the second shutter  515 . 
     The state in which the supplied hole  514   c  is exposed by the second shutter  515  is a state in which the second shutter  515  is open. In this case, the first recessed portions  514   d  of the toner-cartridge supporter  514  and the second recessed portions  515   b  of the second shutter  515  are different in phase in the circumferential direction, and the second recessed portions  515   b  are located on a front side of the first recessed portions  514   d.    
     Thus, in the process cartridge  51 , the second shutter  515  and the toner-cartridge supporter  514  can be moved relative to each other by pivotal movement of the second shutter  515  relative to the toner-cartridge supporter  514 , allowing the second shutter  515  to expose and close the supplied hole  514   c.    
     (Guide Groove) 
     Guide grooves  513  are formed in right and left inner surfaces of the side walls  511   a  of the respective cartridge frames  511 . Each of the guide grooves  513  extends substantially in the up and down direction and is inclined such that a lower portion of each of the guide grooves  513  is located on a rear side of an upper portion of the guide groove  513 . The guide grooves  513  are located above the toner-cartridge supporter  514 . 
     Upper ends of the respective guide grooves  513  are open, allowing the guide projecting portions  526  of the toner cartridge  52  to be inserted into the respective guide grooves  513  from above. The toner cartridge  52  can be mounted to the process cartridge  51  by inserting the guide projecting portions  526  into the respective guide grooves  513 . 
     When the guide projecting portions  526  are inserted into the respective guide grooves  513 , each of the guide projecting portions  526  is guided along the inclined posture of a corresponding one of the guide grooves  513  in an inclined posture in which a lower end portion of the guide projecting portion  526  is located on a rear side of an upper end portion of the guide projecting portion  526 . When the guide projecting portions  526  inserted into the respective guide grooves  513  have reached lower end portions of the respective guide grooves  513 , the toner cartridge  52  is mounted to the process cartridge  51 . The lower end portions of the respective guide grooves  513  respectively have engaging grooves  513   a , of which width extends in a direction intersecting the direction in which the guide groove  513  extends. 
     The toner cartridge  52  mounted to the process cartridge  51  can pivot with respect to the process cartridge  51  between a first position (illustrated in  FIG.  9 A ) at which the upper end portion of the toner cartridge  52  is inclined upward and a second position (illustrated in  FIG.  9 B ) at which the upper end portion is moved rearward from the first position and stands upright. 
     That is, pivotal movement of the guide projecting portions  526  to be inserted into the guide grooves  513  with respect to the process cartridge  51  is restricted by the guide grooves  513  until the guide projecting portions  526  reach the lower end portions of the respective guide grooves  513 . However, when the guide projecting portions  526  have reached the lower end portions of the respective guide grooves  513 , the pivotal movement of the guide projecting portions  526  with respect to the process cartridge  51  is allowed by the engaging grooves  513   a  formed at the lower end portions of the respective guide grooves  513 . 
     This allows the toner cartridge  52  located at the first position to pivot with respect to the process cartridge  51  to move to the second position. It is noted that, when the toner cartridge  52  has pivoted from the first position to the second position, rear surfaces of the respective guide projecting portions  526  come into contact with the respective engaging grooves  513   a , thereby preventing further rearward pivotal movement of the toner cartridge  52 . 
     When the toner cartridge  52  is located at the second position, upper surfaces of the respective guide projecting portions  526  are in contact with the respective engaging grooves  513   a , preventing upward movement of the toner cartridge  52  with respect to the process cartridge  51 . This prevents the toner cartridge  52  located at the second position from coming out of the process cartridge  51 . 
     (Developing Unit) 
     The unit frame  591  of the developing unit  59  has developing chambers  59   a . The developing roller  55  and the supply roller  56  are disposed in the developing chambers  59   a . The unit frame  591  includes support stays  591   a  each protruding frontward. The support stays  591   a  are provided on the right and left end portions of the unit frame  591 . The developing unit  59  includes a support shaft  592  extending in the right and left direction and supported by the right and left side walls  511   a.    
     The support stays  591   a  are pivotably supported by the support shaft  592 . As a result, the unit frame  591  of the developing unit  59  is supported by the cartridge frames  511  so as to be pivotable about the support shaft  592 . That is, the developing unit  59  is supported by the cartridge frames  511  so as to be swingable with respect to the photoconductive drum  54 . 
     Each of the guide holes  511   c  of the respective side walls  511   a  is elongated with its major axis direction coinciding with a direction in which the roller shaft  55   a  of the developing roller  55  pivots about the support shaft  592 . Each of the roller shafts  55   a  is slidable in an area of a corresponding one of the guide holes  511   c.    
     When the roller shafts  55   a  are slid in the areas of the respective guide holes  511   c , the unit frame  591  is pivotable in a direction in which the developing roller  55  is in pressing contact with the photoconductive drum  54  and in a direction in which the developing roller  55  moves away from the photoconductive drum  54 . The unit frame  591  is urged in the direction in which the developing roller  55  is in pressing contact with the photoconductive drum  54  by an urging spring  593  disposed between the unit frame  591  and the toner-cartridge supporter  514 . 
     Thus, the unit frame  591  of the developing unit  59  is supported by the cartridge frames  511  of the process cartridge  51  so as to be pivotable about the support shaft  592 . As a result, the developing roller  55  supported by the developing unit  59  also becomes pivotable with respect to the photoconductive drum  54 , resulting in stable contact state of the developing roller  55  with the photoconductive drum  54 . 
     The pivotal direction of the developing roller  55  pivoting with the unit frame  591  is limited by the guide holes  511   c  to the direction in which the developing roller  55  is in pressing contact with the photoconductive drum  54  and the direction in which the developing roller  55  moves away from the photoconductive drum  54 . This prevents the positions of one and the other end portions of the developing roller  55  from moving in the circumferential direction of the photoconductive drum  54 , for example, making it possible to keep the parallelism of the developing roller  55  and the photoconductive drum  54 . 
     An upper surface of the unit frame  591  has an opening  591   b  elongated with its longitudinal direction coinciding with the right and left direction. The opening  591   b  is formed in the open/close surface portion  514   b  below the supplied hole  514   c . The opening  591   b  has a size corresponding to the size of the supplied hole  514   c.    
     The opening  591   b  and the supplied hole  514   c  overlap each other in position when viewed in the up and down direction, and communicate with each other. The toner to be supplied to the developing unit  59  is allowed to pass through the opening  591   b  and the supplied hole  514   c . When the second shutter  515  is open, the toner is suppliable into the unit frame  591  through the supplied hole  514   c  and the opening  591   b.    
     The toner supplied into the unit frame  591  is supplied to the supply roller  56  in the developing chambers  59   a  by screws  591   c ,  591   d  disposed in the unit frame  591 . Thus, the developing unit  59  has the opening  591   b  for supplying the toner to the developing chambers  59   a.    
     (Resilient Member) 
     A resilient member  516  is provided between the upper surface of the unit frame  591  and the open/close surface portion  514   b  of the toner-cartridge supporter  514 . The resilient member  516  has a communication opening  516   a  elongated with its longitudinal direction coinciding with the right and left direction. The communication opening  516   a  has a size corresponding to the size of the supplied hole  514   c  of the open/close surface portion  514   b.    
     The communication opening  516   a  overlaps the supplied hole  514   c  and the opening  591   b  in position when viewed in the up and down direction. The communication opening  516   a  and each of the supplied hole  514   c  and the opening  591   b  communicate with each other. 
     A space is formed between the upper surface of the unit frame  591  and the open/close surface portion  514   b  in the up and down direction. This space is filled with the resilient member  516 . In this construction, since the resilient member  516  has the communication opening  516   a , a space between a portion of the upper surface of the unit frame  591  around the opening  591   b  and a portion of the open/close surface portion  514   b  around the supplied hole  514   c  is filled with the resilient member  516 . 
     The resilient member  516  is a sponge member, for example, which is extended and contracted by elastic deformation of the resilient member  516 . Thus, even in the case where the unit frame  591  is swung about the support shaft  592  with respect to the cartridge frames  511  to change the size of the space between the unit frame  591  and the open/close surface portion  514   b , this space can be filled by the resilient member  516  following the operation. 
     This prevents the toner having passed through the supplied hole  514   c  from leaking to the outside from the space between the unit frame  591  and the open/close surface portion  514   b.    
     (Lock Member) 
     The process cartridge  51  includes a pair of right and left lock members  70  movable between a lock position at which the lock members  70  lock the process cartridge  51  to the drawer  60  and a release position at which the lock between the process cartridge  51  and the drawer  60  is released. Each of the lock members  70  is disposed at a joint position between the toner-cartridge supporter  514  and a corresponding one of the side walls  511   a  of the respective cartridge frames  511 . Each of the lock members  70  includes a pivot shaft  71 , an operating arm  72 , and a lock arm  73 . 
     The pivot shaft  71  is pivotably supported by the side wall  511   a  in a state in which the axis direction of the pivot shaft  71  coincides with the front and rear direction. The operating arm  72  extends inward from the pivot shaft  71  in the right and left direction and pivotable with the pivot shaft  71 . An operating projection  72   a  protruding upward is formed at a distal end portion of the operating arm  72 . The lock arm  73  extends downward from the pivot shaft  71  pivotably with the pivot shaft  71 . A lock projection  73   a  (as one example of a first engaging portion) protruding outward in the right and left direction is formed at a lower end portion of the lock arm  73 . 
     As illustrated in  FIG.  11   , when the lock member  70  is located at the release position, the operating projection  72   a  of the operating arm  72  protrudes upward from the support surface portion  514   a  of the toner-cartridge supporter  514 , and the lock projection  73   a  of the lock arm  73  does not protrude outward from the side wall  511   a  in the right and left direction. As illustrated in  FIG.  13   , when the lock member  70  is located at the lock position, the operating projection  72   a  of the operating arm  72  does not protrude upward from the support surface portion  514   a , and the lock projection  73   a  of the lock arm  73  protrudes outward from the side wall  511   a  in the right and left direction. 
     Each of the side wall  511   a  has an opening  511   d  opening in its outer surface in the right and left direction. The lock projection  73   a  of the lock arm  73  can protrude from the side wall  511   a  through the opening  511   d  in the right and left direction. 
     In the state in which the process cartridge  51  is mounted to the drawer  60 , the side walls  511   a  of the process cartridge  51  and the respective side frames  61  of the drawer  60  are opposed to each other. A lock hole  61   a  (as one example of a second engaging portion) is formed in a surface of each of the side frames  61  which faces a corresponding one of the side walls  511   a . The lock projection  73   a  of the lock arm  73  which protrudes outward from the side wall  511   a  in the right and left direction is insertable into the lock hole  61   a . It is noted that the lock projection  73   a  and the lock hole  61   a  at least need to be engaged with each other to lock the process cartridge  51  and the toner cartridge  52  to each other. For example, the image forming apparatus  1  may be configured such that the lock arm  73  has a lock hole, and a lock projection is formed on the side frame  61 . 
     That is, the lock members  70  include the respective lock projections  73   a  to be inserted into the respective lock holes  61   a  of the drawer  60 , and the drawer  60  has the lock holes  61   a  in which the lock projections  73   a  of the respective lock members  70  are inserted. 
     Each of the lock members  70  includes an urging spring  74  urging the lock member  70  toward the release position. When the lock member  70  is in a natural state in which no operating force acts on the operating arm  72 , the lock member  70  is located at the release position by the urging force of the urging spring  74 . 
     When the operating projection  72   a  of the operating arm  72  is pressed downward, the operating arm  72  pivots downward, and the lock arm  73  pivots outward in the right and left direction against the urging force of the urging spring  74 , moving the lock member  70  to the lock position. 
     As illustrated in  FIG.  11   , in a state in which the process cartridge  51  is mounted to the drawer  60 , and the toner cartridge  52  is removed from the process cartridge  51 , no operating force acts on the operating arm  72 , keeping the lock member  70  at the release position. 
     When the lock member  70  is located at the release position, the lock projection  73   a  does not protrude outward from the side wall  511   a  in the right and left direction, and thus the lock projection  73   a  is not inserted in the lock hole  61   a , so that the lock between the process cartridge  51  and the drawer  60  is released. In the state in which the lock between the process cartridge  51  and the drawer  60  is released, the process cartridge  51  is allowed to move with respect to the drawer  60 , allowing the process cartridge  51  to be removed from the drawer  60 . 
     When the toner cartridge  52  is mounted to the process cartridge  51  mounted to the drawer  60  illustrated in  FIG.  11   , the toner supplier  522  of the toner cartridge  52  comes into contact with the operating projections  72   a  of the respective operating arms  72 , thereby pressing the operating projections  72   a  downward. 
     As illustrated in  FIG.  13   , when the operating projections  72   a  are pressed downward by the toner cartridge  52 , the lock members  70  are moved to the lock position, so that the lock projections  73   a  are inserted in the respective lock holes  61   a . When the lock projections  73   a  are inserted in the respective lock holes  61   a , the process cartridge  51  is locked to the drawer  60 . In the state in which the process cartridge  51  is locked to the drawer  60 , movement of the process cartridge  51  with respect to the drawer  60  is prevented, preventing separation of the process cartridge  51  from the drawer  60 . 
     Thus, in the state in which the process cartridge  51  is mounted to the drawer  60 , and the toner cartridge  52  is mounted to the process cartridge  51 , the lock members  70  are located at the lock position at which the lock members  70  lock the process cartridge  51  to the drawer  60 , and in the state in which the process cartridge  51  is mounted to the drawer  60 , and the toner cartridge  52  is removed from the process cartridge  51 , the lock members  70  are located at the release position at which the lock between the process cartridge  51  and the drawer  60  is released. 
     Thus, when the toner cartridge  52  mounted to the process cartridge  51  is removed from the process cartridge  51 , the lock members  70  are located at the lock position, and the process cartridge  51  is locked by the lock members  70 . Thus, when the toner cartridge  52  is moved from the process cartridge  51 , the process cartridge  51  does not move, facilitating removing the toner cartridge  52 . 
     In the state in which the toner cartridge  52  is removed from the process cartridge  51 , the lock members  70  are located at the release position, allowing the process cartridge  51  to be removed from the drawer  60 . Thus, when the process cartridge  51  is removed from the drawer  60 , the process cartridge  51  can be removed without operating the lock members  70 , making it possible to reduce the number of operations of the user. 
     When mounting the toner cartridge  52  to the process cartridge  51  in the state in which the process cartridge  51  is mounted to the drawer  60 , the lock members  70  are moved from the release position to the lock position by contacting the toner cartridge  52 . 
     Thus, when the toner cartridge  52  is mounted to the process cartridge  51 , the process cartridge  51  is automatically secured to the drawer  60  by the lock members  70 , making it possible to reduce the number of operations of the user. 
     When the lock members  70  are moved to the lock position, the lock projections  73   a  of the respective lock members  70  are inserted into the respective lock holes  61   a  of the drawer  60 , making it easy to secure the process cartridge  51  to the drawer  60 . 
     Opening and Closing of First Shutter and Second Shutter 
     As illustrated in  FIG.  14   , the first shutter  524  and the second shutter  515  are closed in the state in which the toner cartridge  52  is removed from the process cartridge  51 . 
     When the guide projecting portions  526  of the toner cartridge  52  in this state are inserted in the respective guide grooves  513  of the side walls  511   a , the toner cartridge  52  is guided in the inclined posture, and the guide projecting portions  526  reach the lower end portions of the respective guide grooves  513 , so that the toner cartridge  52  is mounted to the process cartridge  51 . 
     In this case, the first projecting portions  524   b  of the first shutter  524  are fitted in the respective first recessed portions  514   d  of the process cartridge  51 , and the second projecting portions  525  of the toner cartridge  52  are fitted in the respective second recessed portions  515   b  of the second shutter  515 . 
     As illustrated in  FIG.  15 A , when the toner cartridge  52  is mounted to the process cartridge  51  by inserting the guide projecting portions  526  in the respective guide grooves  513 , the toner cartridge  52  is mounted to the process cartridge  51  in the state in which the toner cartridge  52  is located at the first position. 
     The toner cartridge  52  mounted to the process cartridge  51  is pivotable about the axis of the toner supplier  522  with respect to the process cartridge  51 . As illustrated in  FIG.  15 B , when the toner cartridge  52  located at the first position pivots rearward, the toner cartridge  52  is moved to the second position. 
     In the process unit  50 , the first shutter  524  and the second shutter  515  are opened and closed by pivotal movement of the toner cartridge  52  mounted to the process cartridge  51  between the first position and the second position. 
     As illustrated in  FIG.  15 A , when the toner cartridge  52  mounted to the process cartridge  51  is located at the first position, the supply hole  522   a  of the toner frame  521  is located on a rear side of the communication opening  524   a  of the first shutter  524 , so that the first shutter  524  is closed. The communication opening  515   a  of the second shutter  515  is located on a rear side of the supplied hole  514   c  of the open/close surface portion  514   b , so that the second shutter  515  is closed. 
     When the toner cartridge  52  is in this state has pivoted to the second position with respect to the process cartridge  51 , the position of the first shutter  524  relative to the position of the toner cartridge  52  is moved in the circumferential direction to open the first shutter  524 , and the position of the second shutter  515  relative to the position of the process cartridge  51  is moved in the circumferential direction to open the second shutter  515 . 
     Specifically, when the toner cartridge  52  has pivoted from the first position to the second position, the supply hole  522   a  of the toner frame  521  is moved frontward. The first shutter  524  does not pivot because movement of the first shutter  524  in the circumferential direction is restricted by fitting of the first projecting portions  524   b  of the first shutter  524  in the respective first recessed portions  514   d  of the process cartridge  51 . 
     Accordingly, the position of the communication opening  524   a  of the first shutter  524  relative to the position of the supply hole  522   a  of the toner frame  521  is moved in the circumferential direction, so that the supply hole  522   a  and the communication opening  524   a  overlap each other in position when viewed in the up and down direction. As a result, the supply hole  522   a  and the communication opening  524   a  communicate with each other to open the first shutter  524 . 
     When the toner cartridge  52  has pivoted from the first position to the second position, the second projecting portions  525  of the toner frame  521  move frontward. Since the second projecting portions  525  are fitted in the respective second recessed portions  515   b  of the second shutter  515 , the second shutter  515  is moved frontward with the second projecting portions  525 . The open/close surface portion  514   b  of the toner-cartridge supporter  514  does not move. 
     Accordingly, the position of the supplied hole  514   c  of the open/close surface portion  514   b  relative to the communication opening  515   a  of the second shutter  515  moves in the circumferential direction, so that the communication opening  515   a  and the supplied hole  514   c  overlap each other in position when viewed in the up and down direction. As a result, the communication opening  515   a  and the supplied hole  514   c  communicate with each other to open the second shutter  515 . 
     In contrast, when the toner cartridge  52  located at the second position has pivoted to the first position with respect to the process cartridge  51 , the position of the first shutter  524  relative to the position of the toner cartridge  52  is moved in the circumferential direction to close the first shutter  524 , and the position of the second shutter  515  relative to the position of the process cartridge  51  is moved in the circumferential direction to close the second shutter  515 . 
     Thus, in the process unit  50 , pivotal movement of the toner cartridge  52  mounted to the process cartridge  51 , with respect to the process cartridge  51  moves the position of the first shutter  524  relative to the position of the toner cartridge  52  to cause the first shutter  524  to open and close the supply hole  522   a.    
     Accordingly, the first shutter  524  can be automatically opened and closed by pivotal movement of the toner cartridge  52  mounted to the process cartridge  51 , with respect to the process cartridge  51 , making it possible to reduce the number of operations of the user. 
     In the process unit  50 , in particular, when the toner cartridge  52  is mounted to the process cartridge  51 , the toner cartridge  52  pivots with respect to the process cartridge  51  in the state in which the first projecting portions  524   b  of the first shutter  524  are fitted in the respective first recessed portions  514   d  of the process cartridge  51 , thereby moving the position of the first shutter  524  relative to the position of the toner cartridge  52  to cause the first shutter  524  to open and close the supply hole  522   a.    
     Accordingly, the first projecting portions  524   b  are fitted into the respective first recessed portions  514   d  by mounting the toner cartridge  52  to the process cartridge  51 , and pivotal movement of the toner cartridge  52  mounted to the process cartridge  51  is caused with respect to the process cartridge  51 , making it possible to cause pivotal movement of the toner cartridge  52  and the first shutter  524  relative to each other to automatically open and close the first shutter  524 . This makes it possible to reduce the number of operations of the user. 
     In the process unit  50 , when the toner cartridge  52  is mounted to the process cartridge  51 , the toner cartridge  52  pivots with respect to the process cartridge  51  in the state in which the second projecting portions  525  of the toner cartridge  52  are fitted in the respective second recessed portions  515   b  of the second shutter  515 , thereby moving the position of the second shutter  515  relative to the cartridge frames  511  to cause the second shutter  515  to open and close the supplied hole  514   c.    
     Accordingly, the position of the second shutter  515  relative to the cartridge frames  511  is moved by pivotal movement of the toner cartridge  52  mounted to the process cartridge  51 , with respect to the process cartridge  51  to automatically open and close the second shutter  515 . This makes it possible to reduce the number of operations of the user. 
     In the process unit  50 , the lock members  70  are located at the lock position in the state in which the toner cartridge  52  is mounted to the process cartridge  51 . Thus, the first position of the toner cartridge  52  is a position at which the lock members  70  are located at the lock position, and the first shutter  524  covers the supply hole  522   a  of the toner cartridge  52  in the state in which the toner cartridge  52  is mounted to the process cartridge  51 . The second position of the toner cartridge  52  is a position at which the lock members  70  are located at the lock position, and the first shutter  524  exposes the supply hole  522   a  of the toner cartridge  52  in the state in which the toner cartridge  52  is mounted to the process cartridge  51 . 
     With this configuration, when the first shutter  524  opens and closes the supply hole  522   a  of the toner cartridge  52 , the toner cartridge  52  moves between the first position and the second position in the state in which the process cartridge  51  is locked by the lock members  70 . This reduces movement of the process cartridge  51  when the first shutter  524  opens and closes the supply hole  522   a , facilitating opening and closing the supply hole  522   a  of the toner cartridge  52 . 
     In the present embodiment, the process cartridge  51  includes the photoconductive drum  54  and the cartridge frames  511 . The cartridge frames  511  support the photoconductive drum  54  rotatably. The cartridge frames  511  support the developing unit  59  such that the developing unit  59  is swingable with respect to the photoconductive drum  54 . 
     It is considered that this process cartridge  51  is configured such that the toner cartridge  52  is mounted to the developing unit  59 , but such configuration causes the following problems. 
     First, the developing unit  59  is swingably supported in the process cartridge  51  at a position user&#39;s hand cannot reach. Thus, when mounting the toner cartridge  52  to the developing unit  59 , the developing unit  59  cannot be secured to prevent swinging, making it difficult to mount the toner cartridge  52  to the developing unit  59 . 
     Secondly, it is difficult to configure a mechanism for opening and closing the first shutter  524  of the toner cartridge  52  in conjunction with operation of mounting the toner cartridge  52  to the developing unit  59 . 
     In the present embodiment, in contrast, the process cartridge  51  is configured such that the toner cartridge  52  is mounted to the cartridge frames  511 , thereby achieving the following effects. 
     First, the cartridge frames  511  are easily supported by the drawer  60  so as not to move, facilitating mounting the toner cartridge  52  to the cartridge frames  511 . 
     Secondly, the mechanism for opening and closing the first shutter  524  of the toner cartridge  5  in conjunction with an operation of mounting the toner cartridge  52  to the cartridge frames  511  can be easily achieved as a mechanism for opening and closing the first shutter  524  by causing the toner cartridge  52  to pivot with respect to the cartridge frames  511  in the state in which the first shutter  524  is coupled to the cartridge frames  511  as in the present embodiment. 
     The lock members  70  are preferably provided on the respective cartridge frames  511  in the case where the lock members  70  that move to the lock position at which the lock members  70  lock the process cartridge  51  to the drawer  60  by contacting the toner cartridge  52  when the toner cartridge  52  is mounted to the process cartridge  51  are provided in the construction in which the toner cartridge  52  is mounted to the cartridge frames  511 . 
     Thus, in the case where the lock members  70  are provided on the respective cartridge frames  511  in the construction in which the toner cartridge  52  is mounted to the cartridge frames  511 , the position of the lock members  70  relative to the toner cartridge  52  is stable when the toner cartridge  52  is mounted to the process cartridge  51 . This ensures reliable contact of the toner cartridge  52  with the lock members  70 , making it possible to reliably move the lock members  70  to the lock position. 
     If the lock members  70  are provided on the developing unit  59  in the construction in which the toner cartridge  52  is mounted to the cartridge frames  511 , the developing unit  59  swings with respect to the cartridge frames  511  when the toner cartridge  52  is mounted to the process cartridge  51 , resulting in reduction in stability of the position of the lock members  70  relative to the toner cartridge  52 . This makes it difficult to design a mechanism for reliably moving the lock members  70  to the lock position.