Patent Publication Number: US-2023132911-A1

Title: Process cartridge, image forming apparatus and toner storage unit

Description:
REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority from Japanese Patent Application No. 2021-179077 and No. 2021-179078, which were filed on Nov. 1, 2021, the disclosures of which are herein incorporated by reference in their entirety. 
     BACKGROUND ART 
     The following disclosure relates to a process cartridge, an image forming apparatus and a toner storage unit. 
     There has been known a conventional cartridge mounted on an image forming apparatus in which toner in a toner storage unit is conveyed upward toward an upper part of the toner storage unit. 
     DESCRIPTION 
     In the above described cartridge, there is a possibility that a sufficient amount of toner is not conveyed from the toner storage unit to a developing unit. 
     An aspect of the disclosure relates to a process cartridge, an image forming apparatus and a toner storage unit capable of conveying a sufficient amount of toner from a toner storage unit to a developing unit. 
     In one aspect of the disclosure, a process cartridge mountable on an image forming apparatus includes a photoconductive drum rotatable around a drum axis extending in a first direction, a developing unit including a developing roller configured to supply toner to the photoconductive drum, and a developer housing supporting the developing roller and capable of storing toner, the developer housing having a developer inlet through which toner is received, and a toner storage unit. The toner storage unit includes a first toner storage chamber capable of storing toner, a second toner storage chamber located above the first toner storage chamber in the state in which the process cartridge is mounted on the image forming apparatus, the second toner storage chamber having a toner discharge outlet through which toner is discharged toward the developer inlet, a first toner conveying member located in the first toner storage chamber and configured to convey the toner in the first toner storage chamber upward toward the second toner storage chamber in an area wider than the toner discharge outlet in the first direction, and a second toner conveying member located in the second toner storage chamber and configured to convey, in the first direction, the toner in the second toner storage chamber toward the toner discharge outlet. 
     In another aspect of the disclosure, an image forming apparatus includes a body housing having an opening, a drawer movable through the opening between an accommodated position at which the drawer is accommodated in the body housing and a drawn position at which the drawer is drawn to a position outside the body housing, a drum cartridge including a photoconductive drum and a developing unit configured to supply toner to the photoconductive drum, the drum cartridge being mounted on the drawer, and a toner storage unit mounted on the drum cartridge and capable of storing toner to be supplied to the developing unit. The toner storage unit includes a lock member movable between a lock position at which the lock member locks the toner storage unit to the drum cartridge and a lock release position at which a lock between the toner storage unit and the drum cartridge is released in the state in which the toner storage unit is mounted on the drum cartridge, the lock member including a lock grip. The lock grip is located at a position lower than an upper end of the toner storage unit in a state in which (i) the toner storage unit is mounted on the drum cartridge, (ii) the lock member is positioned at the lock position, (iii) the drum cartridge is mounted on the drawer, and (iv) the drawer is positioned at the accommodated position. 
     In another aspect of the disclosure, an image forming apparatus includes a body housing having an opening, a drawer movable through the opening between an accommodated position at which the drawer is accommodated in the body housing and a drawn position at which the drawer is drawn to a position outside the body housing, a first drum cartridge including a first photoconductive drum and a first developing unit configured to supply toner to the first photoconductive drum, the first drum cartridge being mounted on the drawer, a first toner storage unit mounted on the first drum cartridge and capable of storing toner to be supplied to the first developing unit, a second drum cartridge including a second photoconductive drum and a second developing unit configured to supply toner to the second photoconductive drum, the second drum cartridge being mounted on the drawer, a second toner storage unit mounted on the second drum cartridge and capable of storing toner to be supplied to the second developing unit. The first toner storage unit includes a lock member movable between a lock position at which the lock member locks the first toner storage unit to the first drum cartridge and a lock release position at which a lock between the first toner storage unit and the first drum cartridge is released in a state in which the first toner storage unit is mounted on the first drum cartridge, the lock member including a lock grip. The lock member is located between the first toner storage unit and the second drum cartridge in a state in which (i) the first toner storage unit is mounted on the first drum cartridge, (ii) the lock member is positioned at the lock position, and (iii) the first drum cartridge and the second drum cartridge are mounted on the drawer. 
    
    
     
       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 embodiments, when considered in connection with the accompanying drawings, in which: 
         FIG.  1    is a schematic view of an image forming apparatus; 
         FIG.  2    is a view for explaining a movement of a drawer illustrated in  FIG.  1   ; 
         FIG.  3    is a view for explaining a process cartridge illustrated in  FIG.  1   ; 
         FIG.  4    is a drum frame illustrated in  FIG.  3   ; 
         FIG.  5    is a perspective view of a developing unit illustrated in  FIG.  3   ; 
         FIG.  6    is a cross sectional view of a toner storage unit taken along line VI-VI in  FIG.  3   ; 
         FIG.  7    is a view illustrating a state in which a developer shutter is positioned at a developer closed position illustrated in  FIG.  5   ; 
         FIG.  8    is a view illustrating a state in which the developer shutter is positioned at a developer open position illustrated in  FIG.  5   ; 
         FIG.  9    is a perspective view of the toner storage unit illustrated in  FIG.  3   ; 
         FIG.  10    is a plan view of the toner storage unit illustrated in  FIG.  9   ; 
         FIG.  11    is a cross sectional view of the toner storage unit illustrated in  FIG.  10    in which a toner shutter is positioned at a toner closed position; 
         FIG.  12    is a cross sectional view of the toner storage unit illustrated in  FIG.  10    in which the toner shutter is positioned at a toner open position; 
         FIG.  13    is a perspective view of a developing unit; and 
         FIG.  14    is a side view of a drum frame illustrated in  FIG.  13   .  FIG.  1    is a plan view of a printer. 
     
    
    
     Image Forming Apparatus 
     There will be described an image forming apparatus with reference to  FIG.  1    and  FIG.  2   . 
     As illustrated in  FIG.  1   , the image forming apparatus  1  includes a body housing  2 , a cover  3 , a sheet cassette  4 , a drawer  5 , a plurality of process cartridges  6 Y,  6 M,  6 C,  6 K, an exposing unit  7 , a transfer unit  8  and a fixing unit  9 . 
     Body Housing 
     The body housing  2  accommodates the sheet cassette  4 , the drawer  5 , the plurality of process cartridges  6 Y,  6 M,  6 C,  6 K, the exposing unit  7 , the transfer unit  8  and the fixing unit  9 . The body housing  2  includes an opening  21 , as illustrated in  FIG.  2   . 
     Cover 
     As illustrated in  FIG.  1    and  FIG.  2   , the cover  3  is movable between a closed position (see  FIG.  1   ) and an open position (see  FIG.  2   ). As illustrated in  FIG.  1   , in a state in which the cover  3  is positioned at the closed position, the cover  3  closes the opening  21 . As illustrated in  FIG.  2   , in a state in which the cover  3  is positioned at the open position, the opening  21  is open. 
     Sheet Cassette 
     As illustrated in  FIG.  1   , the sheet cassette  4  is capable of storing a sheet S. The sheet S stored in the sheet cassette  4  is conveyed toward a secondary transfer roller  83 . The secondary transfer roller  83  will be described below. 
     Drawer 
     As illustrated in  FIG.  1    and  FIG.  2   , in the state in which the cover  3  is positioned at the open position, the drawer  5  is movable through the opening  21  between an accommodated position (see  FIG.  1   ) and a drawn position (see  FIG.  2   ). As illustrated in  FIG.  1   , in a state in which the drawer  5  is positioned at the accommodated position, the drawer  5  is accommodated in the body housing  2 . As illustrated in  FIG.  2   , in a state in which the drawer  5  is positioned at the drawn position, the drawer  5  is drawn to a position outside the body housing  2 . 
     Process Cartridge 
     As illustrated in  FIG.  1   , each of the plurality of process cartridges  6 Y,  6 M,  6 C,  6 K is mountable on the image forming apparatus  1 . Each of the plurality of process cartridges  6 Y,  6 M,  6 C,  6 K is mountable in the body housing  2 . The plurality of process cartridges  6 Y,  6 M,  6 C,  6 K are arranged in a direction in which the drawer  5  moves. 
     The process cartridge  6 Y includes a drum cartridge  6 YA and a toner storage unit  6 YB. In other words, the image forming apparatus  1  includes the drum cartridge  6 YA and the toner storage unit  6 YB. 
     It is noted that each of the process cartridges  6 M,  6 C,  6 K is explained in the same manner as the process cartridge  6 Y. That is, the process cartridge  6 M includes a drum cartridge  6 MA and a toner storage unit  6 MB. In other words, the image forming apparatus  1  includes the drum cartridges  6 YA,  6 MA and the toner storage units  6 YB,  6 MB. An explanation of each of the process cartridges  6 M,  6 C,  6 K is dispensed with. 
     Drum Cartridge 
     The drum cartridge  6 YA is mounted on the drawer  5 . The drum cartridge  6 YA includes a photoconductive drum  61 Y, a charging unit  62 Y and a developing unit  63 Y. In other words, the process cartridge  6 Y includes the photoconductive drum  61 Y, the charging unit  62 Y and the developing unit  63 Y. 
     It is noted that each of the drum cartridges  6 MA,  6 CA,  6 KA is explained in the same manner as the drum cartridge  6 YA. That is, the drum cartridge  6 MA includes a photoconductive drum  61 M and a developing unit  63 M. The drum cartridge  6 MA is mounted on the drawer  5 . The developing unit  63 M is capable of supplying toner to the photoconductive drum  61 M. An explanation of each of the drum cartridges  6 MA,  6 CA,  6 KA is dispensed with. 
     Photoconductive Drum 
     The photoconductive drum  61 Y extends in a first direction. The photoconductive drum  61 Y has a cylindrical shape. The photoconductive drum  61 Y is rotatable around a drum axis A 1 . The drum axis A 1  extends in the first direction. In a state in which the process cartridge  6 Y is mounted on the image forming apparatus  1 , the photoconductive drum  61 Y is located below the transfer unit  8 . 
     Charging Unit 
     The charging unit  62 Y charges a circumferential surface of the photoconductive drum  61 Y. Specifically, the charging unit  62 Y is a charging roller. It is noted that the charging unit  62 Y may be a scorotron type charging unit. 
     Developing Unit 
     The developing unit  63 Y is capable of supplying toner to the photoconductive drum  61 Y. The developing unit  63 Y includes a developing roller  631 Y and a developer housing  632 Y. 
     The developing roller  631 Y is capable of supplying the toner in the developer housing  632 Y to the photoconductive drum  61 Y. The developing roller  631 Y is in contact with the photoconductive drum  61 Y. The developing roller  631 Y may be configured such that the developing roller  631 Y is capable of being apart from the photoconductive drum  61 Y. The developing roller  631 Y extends in the first direction. The developing roller  631 Y includes a column shape. The developing roller  631 Y is rotatable around a developer axis A 2 . The developer axis A 2  extends in the first direction. 
     The developer housing  632 Y supports the developing roller  631 Y. The developer housing  632 Y is capable of storing toner supplied from the toner storage unit  6 YB. 
     Toner Storage Unit 
     The toner storage unit  6 YB is capable of storing toner which is toner to be supplied to the developing unit  63 Y. The toner storage unit  6 YB is mounted on the drum cartridge  6 YA. More specifically, the toner storage unit  6 YB is a toner cartridge mountable on and removable from the developing unit  63 Y. 
     It is noted that each of the toner storage units  6 MB,  6 CB,  6 KB is explained in the same manner as the toner storage unit  6 YB. That is, the toner storage unit  6 MB is capable of storing the toner which is to be supplied to the developing unit  63 M. The toner storage unit  6 MB is mounted on the drum cartridge  6 MA. An explanation of each of the toner storage units  6 MB,  6 CB,  6 KB is dispensed with. 
     Exposing Unit 
     The exposing unit  7  is capable of exposing a surface of the photoconductive drum  61 Y charged by the charging unit  62 Y, a surface of the photoconductive drum  61 M charged by a charging unit  62 M, a surface of a photoconductive drum  61 C charged by a charging unit  62 C, and a surface of a photoconductive drum  61 K charged by a charging unit  62 K. In the present embodiment, the exposing unit  7  is a laser scanning unit. The exposing unit  7  may be a LED array. 
     In a state in which the plurality of process cartridges  6 Y,  6 M,  6 C,  6 K are mounted on the drawer  5  and the drawer  5  is positioned at the accommodated position, the exposing unit  7  is located below the plurality of process cartridges  6 Y,  6 M,  6 C,  6 K. 
     Transfer Unit 
     In a state in which the drum cartridge  6 YA,  6 MA,  6 CA,  6 KA are mounted on the drawer  5  and the drawer  5  is positioned at the accommodated position, the transfer unit  8  is located above the photoconductive drums  61 Y,  61 M,  61 C,  61 K. The transfer unit  8  transfers toner images formed on the photoconductive drums  61 Y,  61 M,  61 C,  61 K onto the sheet S. 
     The transfer unit  8  includes an intermediate transfer belt  81 , a plurality of primary transfer rollers  82 Y,  82 M,  82 C,  82 K and the secondary transfer roller  83 . 
     Intermediate Transfer Belt 
     In a state in which the drum cartridge  6 YA,  6 MA,  6 CA,  6 KA are mounted on the drawer  5 , the drawer  5  is positioned at the accommodated position and the cover  3  is positioned at the closed position, the intermediate transfer belt  81  comes into contact with the photoconductive drums  61 Y,  61 M,  61 C,  61 K. In the state in which the drum cartridge  6 YA,  6 MA,  6 CA,  6 KA are mounted on the drawer  5  and the drawer  5  is positioned at the accommodated position, the intermediate transfer belt  81  passes through between the photoconductive drum  61 Y and the primary transfer roller  82 Y, between the photoconductive drum  61 M and the primary transfer roller  82 M, between the photoconductive drum  61 C and the primary transfer roller  82 C and between the photoconductive drum  61 K and the primary transfer roller  82 K. 
     Primary Transfer Roller 
     The primary transfer roller  82 Y transfers a toner image formed on the photoconductive drum  61 Y onto the intermediate transfer belt  81 . The primary transfer roller  82 M transfers a toner image formed on the photoconductive drum  61 K onto the intermediate transfer belt  81 . The primary transfer roller  82 C transfers a toner image formed on the photoconductive drum  61 C onto the intermediate transfer belt  81 . The primary transfer roller  82 K transfers a toner image formed on the photoconductive drum  61 K onto the intermediate transfer belt  81 . 
     Secondary Transfer Roller 
     The secondary transfer roller  83  is in contact with the intermediate transfer belt  81 . The sheet S conveyed from the sheet cassette  4  passes through between the intermediate transfer belt  81  and the secondary transfer roller  83 . When the sheet S passes through between the intermediate transfer belt  81  and the secondary transfer roller  83 , the secondary transfer roller  83  transfers the toner image having been transferred to the intermediate transfer belt  81  onto the sheet S. 
     Fixing Unit 
     The fixing unit  9  fixes the toner image onto the sheet S by heating and pressing the sheet S on which the toner image is transferred. The sheet S having passed through the fixing unit  9  is discharged to an upper surface of the body housing  2 . 
     Detail Of Process Cartridge 
     There will be described the process cartridge  6 Y in detail with reference to  FIG.  3    to  FIG.  12   . 
     Drum Cartridge 
     As illustrated in  FIG.  3   , the drum cartridge  6 YA includes a drum frame  64 Y, a drum cleaner  65 Y and a handle  66 Y in addition to the photoconductive drum  61 Y, the charging unit  62 Y and the developing unit  63 Y which are described above. In other words, the process cartridge  6 Y includes the drum cleaner  65 Y. 
     Drum Frame 
     As illustrated in  FIG.  4   , the drum frame  64 Y includes two drum side plates  641 A,  641 B. 
     The drum side plate  641 A is located at a first end of the drum frame  64 Y in the first direction. The drum side plate  641 A supports a first end of the photoconductive drum  61 Y in the first direction. The drum side plate  641 A includes a hole  6411 A and a hole  6412 A. The drum side plate  641 A extends in a second direction and a third direction. 
     In a state in which the image forming apparatus  1  is placed on a horizontal plane and the process cartridge  6 Y is mounted on the image forming apparatus  1 , the second direction is a horizontal direction. The second direction intersects the first direction. It is preferable that the second direction is orthogonal to the first direction. In the state in which the image forming apparatus  1  is placed on the horizontal plane and the process cartridge  6 Y is mounted on the image forming apparatus  1 , the third direction is an up and down direction. The third direction intersects each of the first direction and the second direction. It is preferable that the third direction is orthogonal to each of the first direction and the second direction. 
     The hole  6411 A is spaced apart from the photoconductive drum  61 Y in a fourth direction. The fourth direction is a direction directed from a position of the drum axis A 1  in  FIG.  3    to a position of the developer axis A 2  in  FIG.  3   . The hole  6411 A is an elongated hole. The hole  6411 A extends in the fourth direction. 
     The hole  6412 A is located between the photoconductive drum  61 Y and the hole  6411 A in the fourth direction. The hole  6412 A is an elongated hole. The hole  6412 A extends in the fourth direction. 
     The drum side plate  641 B is located at a second end of the drum frame  64 Y in the first direction. The drum side plate  641 B supports a second end of the photoconductive drum  61 Y in the first direction. The drum side plate  641 B includes a hole  6411 B and a hole  6412 B, which is not illustrated. The drum side plate  641 B extends in the second direction and the third direction. 
     The hole  6411 B is spaced apart from the photoconductive drum  61 Y in the fourth direction. The hole  6411 B is an elongated hole. The hole  6411 B extends in the fourth direction. 
     The hole  6412 B is located between the photoconductive drum  61 Y and the hole  6411 B in the fourth direction. The hole  6412 B is an elongated hole. The hole  6412 B extends in the fourth direction. 
     Detail Of Developing Unit 
     As illustrated in  FIG.  3   , the developing unit  63 Y includes a supplying roller  633 Y, a toner conveying member  634 Y, a developer shutter  635 Y, two protrusions  636 A,  637 A (see  FIG.  5   ) and two protrusions  636 B,  637 B (see  FIG.  5   ) in addition to the developing roller  631 Y and the developer housing  632 Y, which are described above. 
     Detail Of Developer Housing 
     As illustrated in  FIG.  3    and  FIG.  5   , the developer housing  632 Y includes a first frame  632 A and a second frame  632 B. 
     First Frame 
     The first frame  632 A supports the developing roller  631 Y. The first frame  632 A accommodates the supplying roller  633 Y and the toner conveying member  634 Y. In a state in which the toner storage unit  6 YB is mounted on the drum cartridge  6 YA, the first frame  632 A is capable of storing the toner conveyed from the toner storage unit  6 YB. The first frame  632 A extends in the first direction. The first frame  632 A has a tubular shape. As illustrated in  FIG.  3   , the first frame  632 A includes a developer inlet  6321  and two developer discharge outlets  6322 A,  6322 B (see in  FIG.  6   ). In other words, the developer housing  632 Y includes the developer inlet  6321  and the two developer discharge outlets  6322 A,  6322 B. 
     As illustrated in  FIG.  6   , the developer inlet  6321  is located at a central part of the first frame  632 A in the first direction. The developer inlet  6321  communicates with an inner space of the first frame  632 A. In the state in which the toner storage unit  6 YB is mounted on the drum cartridge  6 YA, the developer inlet  6321  is capable of receiving toner from the toner storage unit  6 YB. As illustrated in  FIG.  3   , the developer inlet  6321  and the developing roller  631 Y are arranged in the second direction. In the state in which the process cartridge  6 Y is mounted on the image forming apparatus  1 , the developer inlet  6321  is located at a position upper than the supplying roller  633 Y. In the state in which the process cartridge  6 Y is mounted on the image forming apparatus  1 , the developer inlet  6321  is located at a position upper than the toner conveying member  634 Y. 
     As illustrated in  FIG.  6   , the developer discharge outlet  6322 A is located at a first end of the first frame  632 A in the first direction. The developer discharge outlet  6322 A is capable of discharging the toner in the developer housing  632 Y. More specifically, the developer discharge outlet  6322 A is capable of discharging the toner in the first frame  632 A. The developer discharge outlet  6322 A communicates with the inner space of the first frame  632 A. In the state in which the process cartridge  6 Y is mounted on the image forming apparatus  1 , the developer discharge outlet  6322 A is located at a position lower than the supplying roller  633 Y. In the state in which the process cartridge  6 Y is mounted on the image forming apparatus  1 , the developer discharge outlet  6322 A is located at a position lower than the toner conveying member  634 Y. 
     The developer discharge outlet  6322 B is located at a second end of the first frame  632 A in the first direction. The developer discharge outlet  6322 B is capable of discharging the toner in the developer housing  632 Y. More specifically, the developer discharge outlet  6322 B is capable of discharging the toner in the first frame  632 A. The developer discharge outlet  6322 B communicates with the inner space of the first frame  632 A. As illustrated in  FIG.  3   , in the state in which the process cartridge  6 Y is mounted on the image forming apparatus  1 , the developer discharge outlet  6322 B is located at a position lower than the supplying roller  633 Y. In the state in which the process cartridge  6 Y is mounted on the image forming apparatus  1 , the developer discharge outlet  6322 B is located at a position lower than the toner conveying member  634 Y. 
     Second Frame 
     In the state in which the toner storage unit  6 YB is mounted on the drum cartridge  6 YA, the second frame  632 B supports the toner storage unit  6 YB. As illustrated in  FIG.  5   , the second frame  632 B is connected to the first frame  632 A. The second frame  632 B extends in the first direction. The second frame  632 B has a tubular shape. The second frame  632 B includes two side plates  6323 A,  6323 B. The second frame  632 B includes an opening  6324 , as illustrated in  FIG.  7   . 
     As illustrated in  FIG.  6   , the side plate  6323 A is located at a first end of the second frame  632 B in the first direction. The side plate  6323 A is located between the first end of the first frame  632 A and the drum side plate  641 A in the first direction. As illustrated in  FIG.  5   , the side plate  6323 A extends in the second direction and the third direction. The side plate  6323 A includes two guides  63231 A,  63232 A and a lock groove  63233 A. It is noted that the guides  63231 A,  63232 A are not illustrated. The guide  63231 A is the same configuration as a guide  63231 B of the side plate  6323 B, which will be described below, and the guide  63232 A is the same configuration as a guide  63232 B of the side plate  6323 B, which will be described below. Accordingly, an explanation of the guide  63231 A,  63232 A is dispensed with. 
     The lock groove  63233 A is located on an opposite side of the photoconductive drum  61 Y with respect to the developing roller  631 Y. The lock groove  63233 A is recessed in the third direction. In the state in which the process cartridge  6 Y is mounted on the image forming apparatus  1 , the lock groove  63233 A is recessed downward. 
     As illustrated in  FIG.  6   , the side plate  6323 B is located at a second end of the second frame  632 B in the first direction. The side plate  6323 B is located between the second end of the first frame  632 A and the drum side plate  641 B in the first direction. As illustrated in  FIG.  7   , the side plate  6323 B extends in the second direction and the third direction. The side plate  6323 B includes the two guides  63231 B,  63232 B and a lock groove  63233 B. The second frame  632 B includes the guide  63231 B. 
     The guide  63231 B guides the toner storage unit  6 YB when the toner storage unit  6 YB is mounted on and removed from the second frame  632 B. The guide  63231 B extends in the second direction. In a state in which the toner storage unit  6 YB is mounted on the drum cartridge  6 YA, and the drum cartridge  6 YA and the drum cartridge  6 MA (see  FIG.  1   ) are mounted on the drawer  5 , the guide  63231 B extends in a direction directed from the drum cartridge  6 YA to the drum cartridge  6 MA. 
     The guide  63232 B is spaced apart from the guide  63231 B in the third direction. In the state in which the process cartridge  6 Y is mounted on the image forming apparatus  1 , the guide  63232 B is located above the guide  63231 B. The guide  63232 B guides the toner storage unit  6 YB together with the guide  63231 B when the toner storage unit  6 YB is mounted on and removed from the second frame  632 B. The guide  63232 B extends in the second direction. 
     The lock groove  63233 B is located on an opposite side of the photoconductive drum  61 Y with respect to the developing roller  631 Y. The lock groove  63233 B is recessed in the third direction. In the state in which the process cartridge  6 Y is mounted on the image forming apparatus  1 , the lock groove  63233 B is recessed downward. 
     Supplying Roller 
     The supplying roller  633 Y supplies the toner in the first frame  632 A to the developing roller  631 Y. The supplying roller  633 Y is in contact with the developing roller  631 Y. The supplying roller  633 Y extends in the first direction. The supplying roller  633 Y has a column shape. The supplying roller  633 Y is rotatable around a supply axis A 3 . The supply axis A 3  extends in the first direction. 
     Toner Conveying Member 
     As illustrated in  FIG.  6   , the toner conveying member  634 Y conveys the toner in the first frame  632 A in the first direction. The toner conveying member  634 Y conveys the toner in the first frame  632 A from the developer inlet  6321  toward the developer discharge outlets  6322 A,  6322 B. In the present embodiment, the toner conveying member  634 Y is an auger screw. The toner conveying member  634  is not limited to the auger screw as long as the toner conveying member  634  can convey the toner. For example, the toner conveying member  634 Y may be a shaft-less screw. 
     Developer Shutter 
     As illustrated in  FIG.  5   , the developer shutter  635 Y is attached to the first frame  632 A. As illustrated in  FIG.  7    and  FIG.  8   , the developer shutter  635 Y is movable between a developer closed position (see  FIG.  7   ) and a developer open position (see  FIG.  8   ). As illustrated in  FIG.  7   , in a state in which the developer shutter  635 Y is positioned at the developer closed position, the developer shutter  635 Y closes the developer inlet  6321  and the developer discharge outlets  6322 A,  6322 B. On the other hand, as illustrated in  FIG.  8   , in a state in which the developer shutter  635 Y is located at the developer open position, the developer inlet  6321  and the developer discharge outlets  6322 A,  6322 B are open. As illustrated in  FIG.  5    and  FIG.  7   , the developer shutter  635 Y includes a developer shutter body  6351  and two engaging portions  6352 A (see  FIG.  5   ),  6352 B (see  FIG.  7   ). 
     The developer shutter body  6351  extends in the first direction. The developer shutter body  6351  includes an opening  6350 . As illustrated in  FIG.  7   , in a state in which the developer shutter  635 Y is positioned at the developer closed position, the opening  6350  is spaced apart from the developer inlet  6321 . As illustrated in  FIG.  8   , in a state in which the developer shutter  635 Y is positioned at the developer open position, the opening  6350  communicates with the developer inlet  6321 . 
     As illustrated in  FIG.  5   , the engaging portion  6352 A is located at a first end of the developer shutter  635 Y in the first direction. In the state in which the toner storage unit  6 YB is mounted on the drum cartridge  6 YA, the engaging portion  6352 A engages with an engaging portion  693 A of the toner storage unit  6 YB, as illustrated in  FIG.  9   . In the present embodiment, the engaging portion  6352 A is a gear. In the state in which the toner storage unit  6 YB is mounted on the drum cartridge  6 YA, the engaging portion  6352 A engages with the engaging portion  693 A of the toner storage unit  6 YB. It is noted that the engaging portion  6352 A is not limited to a gear as long as a lock member  69 Y of the toner storage unit  6 YB (see  FIG.  9   ) and the developer shutter  635 Y can be geared to each other. 
     As illustrated in  FIG.  7   , the engaging portion  6352 B is located at a second end of the developer shutter  635 Y in the first direction. In the state in which the toner storage unit  6 YB is mounted on the drum cartridge  6 YA, the engaging portion  6352 B engages with an engaging portion  693 B of the toner storage unit  6 YB (see  FIG.  9   ). The engaging portion  6352 B is the same configuration as the engaging portion  6352 A. Accordingly, an explanation of the engaging portion  6352 B is dispensed with. 
     Protrusion 
     As illustrated in  FIG.  5   , a protrusion  636 A is located at a first end of the developing unit  63 Y in the first direction. The protrusion  636 A extends in the first direction. In the present embodiment, the protrusion  636 A extends from a first side outer surface of the developer housing  632 Y in the first direction. The protrusion  636 A may be attached to the first outer surface of the developer housing  632 Y in the first direction. The protrusion  636 A has a column shape. The protrusion  636 A is fitted into the hole  6411 A of the drum side plate  641 A (see  FIG.  4   ). 
     A protrusion  637 A is spaced apart from the protrusion  636 A in the fourth direction. The protrusion  637 A is located between the photoconductive drum  61 Y (see  FIG.  3   ) and the protrusion  636 A in the fourth direction. The protrusion  637 A is located at a first end of the developer housing  632 Y in the first direction. The protrusion  637 A extends in the first direction. In the present embodiment, the protrusion  637 A extends from the first side outer surface of the developer housing  632 Y in the first direction. The protrusion  637 A may be attached to the first side outer surface of the developer housing  632 Y in the first direction. The protrusion  637 A has a column shape. The protrusion  637 A may be a first end of a shaft of the developing roller  631 Y. The protrusion  637 A is fitted into the hole  6412 A of the drum side plate  641 A (see  FIG.  4   ). 
     Protrusion 
     As illustrated in  FIG.  3   , a protrusion  636 B is located at a second end of the developing unit  63 Y in the first direction. The protrusion  636 B extends in the first direction. In the present embodiment, the protrusion  636 B extends from a second side outer surface of the developer housing  632 Y in the first direction. The protrusion  636 B may be attached to the second side outer surface of the developer housing  632 Y in the first direction. The protrusion  636 B has a column shape. The protrusion  636 B is fitted into the hole  6411 B of the drum side plate  641 B (see  FIG.  4   ). 
     As illustrated in  FIG.  5   , the protrusion  637 B is spaced apart from the protrusion  636 B in the fourth direction. The protrusion  637 B is located between the photoconductive drum  61 Y and the protrusion  636 B in the fourth direction. The protrusion  637 B is located at the second end of the developing unit  63 Y in the first direction. The protrusion  637 B extends in the first direction. In the present embodiment, the protrusion  637 B extends from the second side outer surface of the developer housing  632 Y in the first direction. The protrusion  637 B may be attached to the second side outer surface of the developer housing  632 Y in the first direction. The protrusion  637 B has a column shape. The protrusion  637 B may be a second end of the shaft of the developing roller  631 . The protrusion  637 B is fitted into the hole  6412 B of the drum side plate  641 B (see  FIG.  6   ). 
     When the protrusion  636 A is fitted into the hole  6411 A of the drum side plate  641 A, the protrusion  637 A is fitted into the hole  6412 A of the drum side plate  641 A, the protrusion  636 B is fitted to the hole  6411 B of the drum side plate  641 B, and the protrusion  637 B is fitted into the hole  6412 B of the drum side plate  641 B, the developing unit  63 Y is movable in the fourth direction with respect to the photoconductive drum  61 Y. 
     Drum Cleaner 
     As illustrated in  FIG.  3   , the drum cleaner  65 Y is provided for the drum frame  64 Y. The drum cleaner  65 Y is located on an opposite side of the developing roller  631 Y in the second direction with respect to the photoconductive drum  61 Y. The drum cleaner  65 Y is capable of cleaning the circumferential surface of the photoconductive drum  61 Y. The drum cleaner  65 Y is located between the drum side plate  641 A and the drum side plate  641 B in the first direction. The drum cleaner  65 Y includes a cleaner housing  651  and a cleaning member  652 . 
     As illustrated in  FIG.  4   , the cleaner housing  651  extends in the first direction. A first end of the cleaner housing  651  in the first direction is connected to the drum side plate  641 A. A second end of the cleaner housing  651  in the first direction is connected to the drum side plate  641 B. The cleaner housing  651  includes an opening  6511 . 
     The cleaning member  652  cleans the circumferential surface of the photoconductive drum  61 Y. The cleaning member  652  extends in the first direction. The cleaning member  652  has a plate shape. An edge of the cleaning member  652  is in contact with the circumferential surface of the photoconductive drum  61 Y. When the photoconductive drum  61 Y rotates, the remaining toner which is toner not transferred to the sheet S and remaining on the circumferential surface of the photoconductive drum  61 Y is removed from the circumferential surface of the photoconductive drum  61 Y by the edge of the cleaning member  652 . The removed toner enters into the cleaner housing  651  through the opening  6511 . 
     Handle 
     As illustrated in  FIG.  3   , in the state in which the process cartridge  6 Y is mounted on the image forming apparatus  1 , the handle  66 Y is located at an upper end of the drum frame  64 Y. The handle  66 Y is gripped by a user when the user removes the drum cartridge  6 YA from the drawer  5 . As illustrated in  FIG.  4   , the handle  66 Y includes a handle grip  661  and two arms  662 A,  662 B. 
     The handle grip  661  is a portion gripped by the user. The handle grip  661  extends in the first direction. The handle grip  661  includes a column shape. 
     The arm  662 A connects a first end of the handle grip  661  in the first direction with the drum side plate  641 A. A first end of the arm  662 A in the first direction is connected to the first end of the handle grip  661  in the first direction. A second end of the arm  662 A in the first direction is connected to the drum side plate  641 A. 
     The arm  662 B connects a second end of the handle grip  661  in the first direction with the drum side plate  641 B. A first end of the arm  662 B in the first direction is connected to the second end of the handle grip  661  in the first direction. A second end of the arm  662 B in the first direction is connected to the drum side plate  641 B. 
     Toner Storage Unit 
     As illustrated in  FIG.  9    and  FIG.  10   , the toner storage unit  6 YB includes a storage unit body  67 Y, a toner shutter  68 Y, the lock member  69 Y, two protrusions  70 A,  71 A and two protrusions  70 B,  71 B. That is, the process cartridge  6 Y includes the lock member  69 Y. 
     Storage Unit Body 
     The storage unit body  67 Y extends in the first direction. The storage unit body  67 Y has a tubular shape. As illustrated in  FIG.  11   , the storage unit body  67 Y includes a first toner storage chamber  671 , a second toner storage chamber  672 , a first toner conveying member  673 , a second toner conveying member  674  and a third toner conveying member  675 . In other words, the toner storage unit  6 YB includes the first toner storage chamber  671 , the second toner storage chamber  672 , the first toner conveying member  673 , the second toner conveying member  674  and the third toner conveying member  675 . That is, the process cartridge  6 Y includes the third toner conveying member  675 . 
     First Toner Storage Chamber 
     The first toner storage chamber  671  is capable of storing toner. In the state in which the process cartridge  6 Y is mounted on the image forming apparatus  1 , the first toner storage chamber  671  is located below the second toner storage chamber  672 . In the state in which the process cartridge  6 Y is mounted on the image forming apparatus  1 , at least a part of the first toner storage chamber  671  is located below the developing unit  63 Y, as illustrated in  FIG.  3   . The at least the part of the first toner storage chamber  671  is located below the developing roller  631 Y of the developing unit  63 Y, as illustrated in  FIG.  3   . A volume of the first toner storage chamber  671  is greater than a volume of the second toner storage chamber  672 . As illustrated in  FIG.  9   , the first toner storage chamber  671  includes two toner inlets  6711 A,  6711 B. In other words, the toner storage unit  6 YB includes the two toner inlets  6711 A,  6711 B. 
     The toner inlet  6711 A is located at a first end of the first toner storage chamber  671  in the first direction. The toner inlet  6711 A communicates with an inner space of the first toner storage chamber  671 . In the state in which the toner storage unit  6 YB is mounted on the drum cartridge  6 YA, the toner inlet  6711 A communicates with the developer discharge outlet  6322 A, as illustrated in  FIG.  6   . In the state in which the toner storage unit  6 YB is mounted on the drum cartridge  6 YA, the toner inlet  6711 A is capable of receiving the toner discharged from the developer discharge outlet  6322 A. 
     The toner inlet  6711 B is located at a second end of the first toner storage chamber  671  in the first direction. The toner inlet  6711 B communicates with the inner space of the first toner storage chamber  671 . In the state in which the toner storage unit  6 YB is mounted on the drum cartridge  6 YA, the toner inlet  6711 B communicates with the developer discharge outlet  6322 B, as illustrated in  FIG.  6   . In the state in which the toner storage unit  6 YB is mounted on the drum cartridge  6 YA, the toner inlet  6711 B is capable of receiving the toner discharged from the developer discharge outlet  6322 B. 
     Second Toner Storage Chamber 
     As illustrated in  FIG.  11   , the second toner storage chamber  672  is capable of storing the toner conveyed from the first toner storage chamber  671 . In the state in which the process cartridge  6 Y is mounted on the image forming apparatus  1 , the second toner storage chamber  672  is located above the first toner storage chamber  671 . In the state in which the process cartridge  6 Y is mounted on the image forming apparatus  1 , the second toner storage chamber  672  and the developing unit  63 Y are arranged in the second direction, as illustrated in  FIG.  3   . The second toner storage chamber  672  has a toner discharge outlet  672 A. 
     The toner discharge outlet  672 A communicates with the inner space of the second toner storage chamber  672 . As illustrated in  FIG.  9   , the toner discharge outlet  672 A is located at a central part of the second toner storage chamber  672  in the first direction. In the state in which the toner storage unit  6 YB is mounted on the drum cartridge  6 YA, the toner discharge outlet  672 A communicates with the developer inlet  6321 , as illustrated in  FIG.  6   . In the state in which the toner storage unit  6 YB is mounted on the drum cartridge  6 YA, the toner discharge outlet  672 A is capable of discharging the toner toward the developer inlet  6321 . 
     First Toner Conveying Member 
     The first toner conveying member  673  is located in the first toner storage chamber  671 . The first toner conveying member  673  is capable of conveying the toner in the first toner storage chamber  671  toward the second toner storage chamber  672 . More specifically, the first toner conveying member  673  includes a shaft  673 A and a blade  673 B. 
     The shaft  673 A extends in the first direction. The shaft  673 A is rotatable around an axis A 4 . The axis A 4  extends in the first direction. 
     The blade  673 B is attached to the shaft  673 A. The blade  673 B is rotatable together with the shaft  673 A. When the shaft  673 A rotates, the blade  673 B rotates together with the shaft  673 A so as to convey the toner upward toward the second toner storage chamber  672 . As illustrated in  FIG.  6   , a length of the blade  673 B is longer than a length of the toner discharge outlet  672 A in the first direction. The length of the blade  673 B in the first direction is substantially the same length as the inner space of the first toner storage chamber  671  in the first direction. The blade  673 B extends over a whole width of the inner space of the first toner storage chamber  671  in the first direction. As a result of this, the first toner conveying member  673  is capable of conveying the toner in the first toner storage chamber  671  upward toward the second toner storage chamber  672  in an area wider than a width of the toner discharge outlet  672 A in the first direction. 
     Second Toner Conveying Member 
     As illustrated in  FIG.  6    and  FIG.  11   , the second toner conveying member  674  is located in the second toner storage chamber  672 . The second toner conveying member  674  is capable of conveying the toner in the second toner storage chamber  672  in the first direction toward the toner discharge outlet  672 A. More specifically, the second toner conveying member  674  conveys the toner from ends of the second storage chamber  672  in the first direction toward a central part of the second toner storage chamber  672  in the first direction such that the toner is conveyed toward the toner discharge outlet  672 A. The second toner conveying member  674  extends in the first direction. In the present embodiment, the second toner conveying member  674  is an auger screw. The second toner conveying member  674  is not limited to the auger screw. For example, the second toner conveying member  674  may be a shaft-less screw. 
     Third Toner Conveying Member 
     As illustrated in  FIG.  11   , the third toner conveying member  675  is located in the first toner storage chamber  671 . The third toner conveying member  675  is spaced apart from the first toner conveying member  673  in the second direction. In the state in which the process cartridge  6 Y is mounted on the image forming apparatus  1 , the third toner conveying member  675  is located below the developer housing  632 Y, as illustrated in  FIG.  3   . The third toner conveying member  675  is capable of conveying the toner in the first toner storage chamber  671  toward the first toner conveying member  673 . The third toner conveying member  675  includes a shaft  675 A and a blade  675 B. 
     The shaft  675 A extends in the first direction. The shaft  675 A is rotatable around an axis A 5 . The axis A 5  extends in the first direction. 
     The blade  675 B is attached to the shaft  675 A. The blade  675 B is rotatable together with the shaft  675 A. When the shaft  675 A rotates, the blade  675 B rotates together with the shaft  675 A so as to convey the toner toward the first toner conveying member  673 . 
     Toner Shutter 
     As illustrated in  FIG.  9   , the toner shutter  68 Y is attached to the storage unit body  67 Y. As illustrated in  FIG.  11    and  FIG.  12   , the toner shutter  68 Y is movable between a toner closed position (see  FIG.  11   ) and a toner open position (see  FIG.  12   ). As illustrated in  FIG.  11   , in a state in which the toner shutter  68 Y is positioned at the toner closed position, the toner shutter  68 Y closes the toner discharge outlet  672 A and the toner inlets  6711 A,  6711 B. As illustrated in  FIG.  12   , in a state in which the toner shutter  68 Y is positioned at the toner open position, the toner discharge outlet  672 A and the toner inlets  6711 A,  6711 B are open. As illustrated in  FIG.  9   , the toner shutter  68 Y includes a toner shutter body  681  and two protrusions  682 A,  682 B. 
     The toner shutter body  681  extends in the first direction. The toner shutter body  681  has an opening  6811 . As illustrated in  FIG.  11   , in the state in which the toner shutter  68 Y is positioned at the toner closed position, the opening  6811  is spaced apart from the toner discharge outlet  672 A. As illustrated in  FIG.  12   , in the state in which the toner shutter  68 Y is positioned at the toner open position, the opening  6811  communicates with the toner discharge outlet  672 A. 
     As illustrated in  FIG.  9   , the protrusion  682 A is located at a first end of the toner shutter  68 Y in the first direction. The protrusion  682 A extends from the toner shutter body  681 . The protrusion  682 A may be attached to the toner shutter body  681 . In the state in which the toner storage unit  6 YB is mounted on the drum cartridge  6 YA, the protrusion  682 A engages with a first end of the developer shutter  635 Y in the first direction. More specifically, the protrusion  682 A is fitted into a hole  6353 A formed at the first end of the developer shutter  635 Y in the first direction. 
     The protrusion  682 B is located at a second end of the toner shutter  68 Y in the first direction. The protrusion  682 B extends from the toner shutter body  681 . The protrusion  682 B may be attached to the toner shutter body  681 . In the state in which the toner storage unit  6 YB is mounted on the drum cartridge  6 YA, the protrusion  682 B engages with a second end of the developer shutter  635 Y in the first direction. More specifically, the protrusion  682 B is fitted into a hole  6353 B formed at the second end of the developer shutter  635 Y in the first direction. 
     When the protrusion  682 A engages with the first end of the developer shutter  635 Y in the first direction and the protrusion  682 B engages with the second end of the developer shutter  635 Y in the first direction, the toner shutter  68 Y is movable together with the developer shutter  635 Y. As a result of this, in the state in which the toner storage unit  6 YB is mounted on the developing unit  63 Y, the toner shutter  68 Y moves from the toner open position to the toner closed position along with a movement of the developer shutter  635 Y from the developer open position to the developer closed position. Moreover, in the state in which the toner storage unit  6 YB is mounted on the developing unit  63 Y, the toner shutter  68 Y moves from the toner closed position to the toner open position along with a movement of the developer shutter  635 Y from the developer closed position to the developer open position. 
     Lock Member 
     As illustrated in  FIG.  9   , the lock member  69 Y is attached to the storage unit body  67 Y. As illustrated in  FIG.  3    and  FIG.  11   , in the state in which the toner storage unit  6 YB is mounted on the developing unit  63 Y of the drum cartridge  6 YA, the lock member  69 Y is movable between a lock position (see  FIG.  3   ) and a lock release position (see  FIG.  11   ). As illustrated in  FIG.  3   , in a state in which the lock member  69 Y is positioned at the lock position, the lock member  69 Y is fitted into the lock groove  63233 A and the lock groove  63233 B (see  FIG.  5   ). As a result of this, in the state in which the lock member  69 Y is positioned at the lock position, the lock member  69 Y locks the toner storage unit  6 YB to the developing unit  63 Y of the drum cartridge  6 YA. On the other hand, in a state in which the toner storage unit  6 YB is mounted on the developing unit  63 Y and the lock member  69 Y is positioned at the lock release position illustrated in  FIG.  11   , the lock member  69 Y is released from the lock groove  63233 A and the lock groove  63233 B (see  FIG.  5   ). As a result of this, in the state in which the lock member  69 Y is positioned at the lock release position, a lock between the toner storage unit  6 YB and the developing unit  63 Y of the drum cartridge  6 YA is released. 
     As illustrated in  FIG.  9   , the lock member  69 Y includes a lock grip  691 , two arms  692 A,  692 B and the two engaging portions  693 A,  693 B. 
     Lock Grip 
     The lock grip  691  is gripped by the user. The lock grip  691  extends in the first direction. The lock grip  691  has a column shape. 
     As illustrated in  FIG.  1   , in a state in which the toner storage unit  6 YB is mounted on the drum cartridge  6 YA, the lock member  69 Y is positioned at the lock position and the drum cartridge  6 YA is mounted on the drawer  5 , the handle grip  661  is located at a position upper than the lock grip  691 . In a state in which the toner storage unit  6 YB is mounted on the drum cartridge  6 YA, the lock member  69 Y is positioned at the lock position, the drum cartridge  6 YA is mounted on the drawer  5  and the drawer  5  is positioned at the accommodated position, the lock grip  691  is located at a position lower than an upper end of the toner storage unit  6 YB. 
     Moreover, in a state in which the toner storage unit  6 YB is mounted on the drum cartridge  6 YA, the lock member  69 Y is positioned at the lock position and the drum cartridge  6 YA and the drum cartridge  6 MA are mounted on the drawer  5 , the lock grip  691  of the lock member  69 Y is located between the toner storage unit  6 YB and the drum cartridge  6 MA. In a state in which the toner storage unit  6 YB is mounted on the drum cartridge  6 YA, the lock member  69 Y is positioned at the lock position and the drum cartridge  6 YA and the drum cartridge  6 MA are mounted on the drawer  5 , the lock grip  691  of the lock member  69 Y is located between the toner storage unit  6 YB and the photoconductive drum  61 M. 
     Arm 
     The arm  692 A connects a first end of the lock grip  691  in the first direction with a protrusion  71 A. A first end of the arm  692 A in the first direction is connected to the first end of the lock grip  691 . A second end of the arm  692 A in the first direction is connected to the protrusion  71 A. The arm  692 A is rotatable around the protrusion  71 A. 
     The arm  692 B connects a second end of the lock grip  691  in the first direction with a protrusion  71 B, as illustrated in  FIG.  10   . A first end of the arm  692 B in the first direction is connected to the second end of the lock grip  691 . A second end of the arm  692 B in the first direction is connected to the protrusion  71 B. The arm  692 B is rotatable around the protrusion 
     Engaging Portion 
     The engaging portion  693 A is provided for the second end of the arm  692 A. In the state in which the toner storage unit  6 YB is mounted on the drum cartridge  6 YA, the engaging portion  693 A engages with the engaging portion  6352 A of the developer shutter  635 Y (see  FIG.  5   ). In the present embodiment, the engaging portion  693 A is a gear. In the state in which the toner storage unit  6 YB is mounted on the drum cartridge  6 YA, the engaging portion  693 A engages with the engaging portion  6352 A of the developer shutter  635 Y. It is noted that the engaging portion  693 A is not limited to the gear as long as the lock member  69 Y and the developer shutter  635 Y can be geared to each other. 
     The engaging portion  693 B is provided for the second end of the arm  692 B. In the state in which the toner storage unit  6 YB is mounted on the drum cartridge  6 YA, the engaging portion  693 B engages with the engaging portion  6352 B of the developer shutter  635 Y (see  FIG.  7   ). In the present embodiment, the engaging portion  693 B is a gear. In the state in which the toner storage unit  6 YB is mounted on the drum cartridge  6 YA, the engaging portion  693 B engages with the engaging portion  6352 B of the developer shutter  635 Y. It is noted that the engaging portion  693 B is not limited to the gear as long as the lock member  69 Y and the developer shutter  635 Y can be geared to each other. 
     In the state in which the toner storage unit  6 YB is mounted on the drum cartridge  6 YA, when the engaging portion  693 A engages with the engaging portion  6352 A of the developer shutter  635 Y and the engaging portion  693 B engages with the engaging portion  6352 B of the developer shutter  635 Y, the developer shutter  635 Y is capable of being geared to the lock member  69 Y. 
     In the state in which the toner storage unit  6 YB is mounted on the developing unit  63 Y, the developer shutter  635 Y moves from the developer open position (see  FIG.  8   ) to the developer closed position (see  FIG.  7   ) along with the movement of the lock member  69 Y from the lock position (see  FIG.  12   ) to the lock release position (see  FIG.  11   ). At this time, the toner shutter  68 Y moves from the toner open position (see  FIG.  12   ) to the toner closed position (see  FIG.  11   ) along with the movement of the developer shutter  635 Y from the developer open position to the developer closed position. 
     Moreover, in the state in which the toner storage unit  6 YB is mounted on the developing unit  63 Y, the developer shutter  635 Y moves from the developer closed position (see  FIG.  7   ) to the developer open position (see  FIG.  8   ) along with the movement of the lock member  69 Y from the lock release position (see  FIG.  11   ) to the lock position (see  FIG.  12   ). At this time, the toner shutter  68 Y moves from the toner closed position (see  FIG.  11   ) to the toner open position (see  FIG.  12   ) along with the movement of the developer shutter  635 Y from the developer closed position to the developer open position. 
     Protrusion 
     As illustrated in  FIG.  9   , a protrusion  70 A is located at the first end of the first toner storage chamber  671  in the first direction. The protrusion  70 A extends from a first side outer surface of the first toner storage chamber  671  in the first direction. The protrusion  70 A may be attached to the first side outer surface of the first toner storage chamber  671  in the first direction. When the toner storage unit  6 YB is mounted on the drum cartridge  6 YA, the protrusion  70 A is guided by the guide  63231 A of the developing unit  63 Y. 
     The protrusion  71 A is spaced apart from the protrusion  70 A. The protrusion  71 A is located at a first end of the second toner storage chamber  672  in the first direction. The protrusion  71 A extends from a first side outer surface of the second toner storage chamber  672  in the first direction. The protrusion  71 A may be attached to the first side outer surface of the second toner storage chamber  672  in the first direction. When the toner storage unit  6 YB is mounted on the drum cartridge  6 YA, the protrusion  71 A is guided by the guide  63232 A of the developing unit  63 Y. 
     Protrusion 
     As illustrated in  FIG.  10   , a protrusion  70 B is located at the second end of the first toner storage chamber  671  in the first direction. The protrusion  70 B extends from a second side outer surface of the first toner storage chamber  671  in the first direction. The protrusion  70 B may be attached to the second side outer surface of the first toner storage chamber  671  in the first direction. When the toner storage unit  6 YB is mounted on the drum cartridge  6 YA, the protrusion  70 B is guided by the guide  63231 B of the developing unit  63 Y (see  FIG.  7   ). 
     The protrusion  71 B is spaced apart from the protrusion  70 B. The protrusion  71 B is located at a second end of the second toner storage chamber  672  in the first direction. The protrusion  71 B extends from a second side outer surface of the second toner storage chamber  672  in the first direction. The protrusion  71 B may be attached to the second side outer surface of the second toner storage chamber  672  in the first direction. When the toner storage unit  6 YB is mounted on the drum cartridge  6 YA, the protrusion  71 B is guided by the guide  63232 B of the developing unit  63 Y (see  FIG.  7   ). 
     Effects 
     According to the process cartridge  6 Y, as illustrated in  FIG.  3   , it is possible to convey the toner by the first toner conveying member  673  from the first toner storage chamber  671  to the second toner storage chamber  672  in the area wider than the width of the toner discharge outlet  672 A in the first direction. 
     As a result, it is possible to convey a large amount of toner, which is larger than an amount of toner supplied from the toner discharge outlet  672 A to the developing unit  63 Y, from the first toner storage chamber  671  to the second toner storage chamber  672 . 
     As a result of this, it is possible to convey a sufficient amount of toner from the second toner storage chamber  672  of the toner storage unit  6 YB to the developing unit  63 Y. 
     According to the process cartridge  6 Y, as illustrated in  FIG.  3   , in the state in which the toner storage unit  6 YB is mounted on the developing unit  63 Y, the developer shutter  635 Y moves from the developer open position (see  FIG.  8   ) to the developer closed position (see  FIG.  7   ) along with the movement of the lock member  69 Y from the lock position (see  FIG.  3   ) to the lock release position (see  FIG.  11   ). In the state in which the toner storage unit  6 YB is mounted on the developing unit  63 Y, the developer shutter  635 Y moves from the developer closed position (see  FIG.  7   ) to the developer open position (see  FIG.  8   ) along with the movement of the lock member  69 Y from the lock release position (see  FIG.  11   ) to the lock position (see  FIG.  3   ). 
     As a result of this, the user can open the developer shutter  635 Y by an operation locking the toner storage unit  6 YB to the developing unit  63 Y, and the user can close the developer shutter  635 Y by an operation releasing the lock between the toner storage unit  6 YB and the developing unit  63 Y. 
     As a result, the user does not need to separately do a locking-unlocking operation of the toner storage unit  6 YB to the developing unit  63 Y and an open-close operation of the developer shutter  635 Y. Accordingly, it is possible to improve usability. 
     Moreover, it is possible to prevent a case in which the developer shutter  635 Y is forgotten to be closed when the toner storage unit  6 YB is removed from the developing unit  63 Y. 
     According to the process cartridge  6 Y, as illustrated in  FIG.  3   , in the state in which the toner storage unit  6 YB is mounted on the developing unit  63 Y, the toner shutter  68 Y moves from the toner open position (see  FIG.  12   ) to the toner closed position (see  FIG.  11   ) along with the movement of the developer shutter  635 Y from the developer open position (see  FIG.  8   ) to the developer closed position (see  FIG.  7   ). In the state in which the toner storage unit  6 YB is mounted on the developing unit  63 Y, the toner shutter  68 Y moves from the toner closed position (see  FIG.  11   ) to the toner open position (see  FIG.  12   ) along with the movement of the developer shutter  635 Y from the developer closed position (see  FIG.  7   ) to the developer open position (see  FIG.  8   ). 
     As a result of this, the user can open not only the developer shutter  635 Y but also the toner shutter  68 Y by the operation of locking the toner storage unit  6 YB to the developing unit  63 Y. Moreover, the user can close not only the developer shutter  635 Y but also the toner shutter  68 Y by the operation of the release of the lock between the toner storage unit  6 YB and the developing unit  63 Y. 
     As a result, the user does not need to separately do the locking-unlocking operation of the toner storage unit  6 YB to the developing unit  63 Y and an open-close operation of the toner shutter  68 Y. Accordingly, it is possible to improve usability. 
     Moreover, it is possible to prevent a case in which the toner shutter  68 Y is forgotten to be closed when the toner storage unit  6 YB is removed from the developing unit  63 Y. 
     According to the process cartridge  6 Y, as illustrated in  FIG.  3   , the toner inlet  6711 A,  6711 B are capable of receiving the toner discharged from the developer discharge outlets  6322 A,  6322 B of the toner storage unit  6 YB. 
     As a result, it is possible to return the toner in the developer housing  632 Y to the toner storage unit  6 YB through the toner inlet  6711 A,  6711 B. 
     Accordingly, it is possible to prevent a case where the toner having deteriorated in the developer housing  632 Y accumulates in the developer housing  632 Y. 
     According to the process cartridge  6 Y, as illustrated in  FIG.  3   , the first toner storage chamber  671  includes the toner inlet  6711 A,  6711 B. 
     As a result, it is possible to return the toner in the developer housing  632 Y to the first toner storage chamber  671 . 
     Accordingly, it is possible to circulate the toner among the developer housing  632 Y, the first toner storage chamber  671  and the second toner storage chamber  672 . Therefore, it is possible to prevent acceleration of deterioration of the toner. 
     According to the process cartridge  6 Y, as illustrated in  FIG.  3   , in the state in which the process cartridge  6 Y is mounted on the image forming apparatus  1 , the first toner storage chamber  671  is located at the below the developing unit  63 Y. 
     Accordingly, it is possible to smoothly return the toner in the developer housing  632 Y to the first toner storage chamber  671  by using gravity. 
     According to the process cartridge  6 Y, as illustrated in  FIG.  6   , the length of the blade  673 B of the first toner conveying member  673  is longer than the length of the toner discharge outlet  672 A in the first direction. 
     Accordingly, it is possible to convey the toner by the first toner conveying member  673  from the first toner storage chamber  671  to the second toner storage chamber  672  in the area wider than the width of the toner discharge outlet  672 A in the first direction. 
     While the invention has been described in conjunction with various example structures outlined above and illustrated in the figures, various alternatives, modifications, variations, improvements, and/or substantial equivalents, whether known or that may be presently unforeseen, may become apparent to those having at least ordinary skill in the art. Accordingly, the example embodiments of the disclosure, as set forth above, are intended to be illustrative of the invention, and not limiting the invention. Various changes may be made without departing from the spirit and scope of the disclosure. Therefore, the disclosure is intended to embrace all known or later developed alternatives, modifications, variations, improvements, and/or substantial equivalents. Some specific examples of potential alternatives, modifications, or variations in the described invention are provided below. 
     Modifications 
     There will be described modifications with reference to  FIG.  13    and  FIG.  14   . In the modifications, the same reference numerals as used in the embodiment are used to designate the corresponding elements of the modifications, and an explanation of which is dispensed with. 
     As illustrated in  FIG.  13   , the developing unit  63 Y may include a protruding portion  100 . The protruding portion  100  is located at the first end of the first frame  632 A in the first direction. The protruding portion  100  extends from the first end of the first frame  632 A in the first direction. The protruding portion  100  extends in the first direction. The protruding portion  100  has a tubular shape. An inner space of the protruding portion  100  communicates with the inner space of the first frame  632 A. The protruding portion  100  has an inlet  100 A. 
     As illustrated in  FIG.  14   , the process cartridge  6 Y includes a toner tube  101  and a collected toner conveying member  102 . 
     The toner tube  101  allows collected toner to pass from the drum cleaner  65 Y toward the protruding portion  100 . The collected toner is toner removed from the circumferential surface of the photoconductive drum  61 Y by the drum cleaner  65 Y. A first end of the toner tube  101  is connected to the drum cleaner  65 Y. A second end of the toner tube  101  is connected to the protruding portion  100 . In other words, the toner tube  101  is connected to the developer housing  632 Y. The toner tube  101  includes a discharge outlet  101 A. The discharge outlet  101 A is located at a second end of the toner tube  101 . The discharge outlet  101 A communicates with the inlet  100 A. 
     The collected toner conveying member  102  is located in the toner tube  101  and in the drum cleaner  65 Y. The collected toner conveying member  102  conveys the collected toner in the drum cleaner  65 Y toward the discharge outlet  101 A. The collected toner conveying member  102  is a shaft-less screw. 
     According to the present modification, it is possible to reuse the toner collected from the circumferential surface of the photoconductive drum  61 Y in the developing operation. 
     In this case, there is a possibility that poor printing occurs due to a certain amount of uncharged toner contained in the collected toner. 
     However, the certain amount of uncharged toner is agitated and diluted when the toner is circulated among the first toner storage chamber  671 , the second toner storage chamber  672  and the developer housing  632 Y. Accordingly, it is possible to prevent an occurrence of the poor printing. 
     It is noted that, in the modification, it is possible to achieve the same effects as the above described embodiment. 
     The image forming apparatus  1  may not include the drawer  5 . In this case, each of the process cartridges  6 Y,  6 M,  6 C,  6 K may be directly mountable on and removable from the image forming apparatus  1 . 
     Moreover, in another aspect of the disclosure, an image forming apparatus may include a body housing, a process cartridge mountable in the body housing. The process cartridge may include a photoconductive drum rotatable around a drum axis extending in a first direction, a developing unit including a developing roller configured to supply toner to the photoconductive drum and a developer housing supporting the developing roller and capable of storing toner, the developer housing having a developer inlet through which toner is received, and a toner storage unit including a first toner storage chamber capable of storing toner, a second toner storage chamber located above the first toner storage chamber in the state in which the process cartridge is mounted on the image forming apparatus, the second toner storage chamber having a discharge outlet through which toner is discharged toward the developer inlet, a first toner conveying member located in the first toner storage chamber and configured to convey the toner in the first toner storage chamber upward toward the second toner storage chamber in an area wider than the toner discharge outlet in the first direction, and a second toner conveying member located in the second toner storage chamber and configured to convey, in the first direction, the toner in the second toner storage chamber toward the toner discharge outlet. 
     Moreover, in another aspect of the disclosure, a toner storage unit may be mountable on a drum cartridge. The drum cartridge may include a photoconductive drum rotatable around a drum axis extending in a first direction, and a developing unit including a developing roller configured to supply toner to the photoconductive drum, and a developer housing supporting the developing roller and capable of storing toner, the developer housing having a developer inlet through which toner is received. The toner storage unit may comprise a first toner storage chamber capable of storing toner, a second toner storage chamber located above the first toner storage chamber in the state in which the drum cartridge is mounted on the image forming apparatus, the second toner storage chamber having a toner discharge outlet through which toner is discharged toward the developer inlet, a first toner conveying member located in the first toner storage chamber and configured to convey the toner in the first toner storage chamber upward toward the second toner storage chamber in an area wider than the toner discharge outlet in the first direction, and a second toner conveying member located in the second toner storage chamber and configured to convey, in the first direction, the toner in the second toner storage chamber toward the toner discharge outlet. 
     In the image forming apparatus, the lock member may be located between the first toner storage unit and the second photoconductive drum in the state in which (i) the first toner storage unit is mounted on the first drum cartridge, (ii) the lock member is positioned at the lock position, and (iii) the first drum cartridge and the second drum cartridge are mounted on the drawer. 
     In the image forming apparatus, the first developing unit may include a developing roller configured to supply toner to the first photoconductive drum, and a developer housing supporting the developing roller and capable of storing toner supplied from the first toner storage unit, the developer housing having a developer inlet through which the toner supplied from the first toner storage unit is received. The developer housing may include a first frame having the developer inlet, and a second frame including a guide configured to guide the first toner storage unit when the first toner storage unit is replaced. The guide may extend in a direction directed from the first drum cartridge toward the second drum cartridge in the state in which (i) the first toner storage unit is mounted on the first drum cartridge, (ii) the lock member is positioned at the lock position, and (iii) the first drum cartridge and the second drum cartridge are mounted on the drawer. 
     In the image forming apparatus, the first developing unit may include a developing roller configured to supply toner to the first photoconductive drum, a developer housing supporting the developing roller and capable of storing toner supplied from the first toner storage unit, the developer housing having a developer inlet through which the toner supplied from the first toner storage unit is received, and a developer shutter movable between a developer closed position at which the developer shutter closes the developer inlet and a developer open position at which the developer inlet is open. In a state in which the first toner storage unit is mounted on the first developing unit, the developer shutter may move from the developer open position to the developer closed position along with a movement of the lock member from the lock position to the lock release position, and the developer shutter may move from the developer closed position to the developer open position along with a movement of the lock member from the lock release position to the lock position.