Patent Publication Number: US-2022236665-A1

Title: Drive and seal assembly for an electrophotographic image forming device

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
     This application is a continuation application of U.S. patent application Ser. No. 16/905,092, filed Jun. 18, 2020, entitled “Drive and Seal Assembly for an Electrophotographic Image Forming Device,” which claims priority to U.S. Provisional Patent Application Ser. No. 62/874,226, filed Jul. 15, 2019, entitled “Drive and Sealing Assembly for an Electrophotographic Image Forming Device,” the contents of which are hereby incorporated by reference in their entireties. 
    
    
     BACKGROUND 
     1. Field of the Disclosure 
     The present disclosure relates generally to image forming devices and more particularly to a drive and sealing assembly for an electrophotographic image forming device. 
     2. Description of the Related Art 
     During the electrophotographic printing process, an electrically charged rotating photoconductive drum is selectively exposed to a laser beam. The areas of the photoconductive drum exposed to the laser beam are discharged creating an electrostatic latent image of a page to be printed on the photoconductive drum. Toner particles from a developer roll are then electrostatically picked up by the latent image on the photoconductive drum creating a toned image on the drum. The toned image is transferred to the print media (e.g., paper) either directly by the photoconductive drum or indirectly by an intermediate transfer member. The toner is then fused to the media using heat and pressure to complete the print. 
     The image forming device&#39;s toner supply is typically stored in one or more replaceable units, such as a toner cartridge. The toner cartridge has a housing that forms a reservoir for storing toner and often includes one or more toner agitators to mix toner in the reservoir to prevent the toner from clumping. At least one end of a shaft of the toner agitator passes through a corresponding opening in the housing permitting the toner agitator to receive rotational motion from a drive train of the replaceable unit or the like. The opening through the housing creates a possible path for toner leakage that must be sealed in order to prevent toner from leaking from the toner cartridge. An assembly for providing rotational motion to the toner agitator and sealing the opening through the housing that the shaft of the toner agitator passes through in an effective, cost-efficient and compact manner is desired. 
     SUMMARY 
     An assembly for use in an electrophotographic image forming device according to one example embodiment includes a housing having a reservoir for holding toner. The housing includes a wall having an inner surface forming a boundary of the reservoir and an outer surface opposite the inner surface. A toner agitator is positioned in the reservoir and has a rotatable shaft. The shaft includes an end portion that passes through an opening in the wall. A gear is mounted on the end portion of the shaft outside of the reservoir and is rotatably coupled to the shaft. An annular seal encircles and is in contact with an outer circumferential surface of the shaft. The annular seal is positioned between an inner axial face of the gear and the outer surface of the wall. The inner axial face of the gear contacts the annular seal and presses the annular seal against the outer surface of the wall. 
     An assembly for use in an electrophotographic image forming device according to another example embodiment includes a housing having a reservoir for holding toner. The housing includes a wall having an inner surface forming a boundary of the reservoir and an outer surface opposite the inner surface. A toner agitator is positioned in the reservoir and has a rotatable shaft. The shaft includes an end portion that passes through an opening in the wall. A boss is integrally formed with and projects from the outer surface of the wall about the opening. A gear is mounted on the end portion of the shaft outside of the reservoir and is rotatably coupled to the shaft. The gear has an inner circumferential surface that contacts and bears against the boss facilitating rotation of the gear about the boss. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings incorporated in and forming a part of the specification, illustrate several aspects of the present disclosure, and together with the description serve to explain the principles of the present disclosure. 
         FIG. 1  is a block diagram of an imaging system according to one example embodiment. 
         FIG. 2  is a cross-sectional view of a toner cartridge of the imaging system according to one example embodiment. 
         FIG. 3  is a perspective view of the toner cartridge according to one example embodiment. 
         FIG. 4  is a perspective view of a developer unit of the toner cartridge of  FIG. 3  showing internal components of the developer unit according to one example embodiment. 
         FIG. 5  is an exploded view of the developer unit of  FIG. 4  according to one example embodiment. 
         FIG. 6  is a perspective view of a drive mechanism of the developer unit of  FIG. 4  according to one example embodiment. 
         FIGS. 7A and 7B  are perspective views illustrating a drive and sealing assembly of the developer unit of  FIG. 4  in an unassembled state according to one example embodiment. 
         FIG. 8  is a side cross-sectional view of the drive and sealing assembly of  FIGS. 7A and 7B  in an assembled state according to one example embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, reference is made to the accompanying drawings where like numerals represent like elements. The embodiments are described in sufficient detail to enable those skilled in the art to practice the present disclosure. It is to be understood that other embodiments may be utilized and that process, electrical, and mechanical changes, etc., may be made without departing from the scope of the present disclosure. Examples merely typify possible variations. Portions and features of some embodiments may be included in or substituted for those of others. The following description, therefore, is not to be taken in a limiting sense and the scope of the present disclosure is defined only by the appended claims and their equivalents. 
     Referring now to the drawings and particularly to  FIG. 1 , there is shown a block diagram depiction of an imaging system  20  according to one example embodiment. Imaging system  20  includes an image forming device  22  and a computer  24 . Image forming device  22  communicates with computer  24  via a communications link  26 . As used herein, the term “communications link” generally refers to any structure that facilitates electronic communication between multiple components and may operate using wired or wireless technology and may include communications over the Internet. 
     In the example embodiment shown in  FIG. 1 , image forming device  22  is a multifunction machine (sometimes referred to as an all-in-one (AIO) device) that includes a controller  28 , a print engine  30 , a laser scan unit (LSU)  31 , a toner cartridge  100 , a user interface  36 , a media feed system  38 , a media input tray  39 , a scanner system  40  and a power supply  42 . Image forming device  22  may communicate with computer  24  via a standard communication protocol, such as, for example, universal serial bus (USB), Ethernet or IEEE 802.xx. Image forming device  22  may be, for example, an electrophotographic printer/copier including an integrated scanner system  40  or a standalone electrophotographic printer. 
     Controller  28  includes a processor unit and associated memory  29 . The processor unit may include one or more integrated circuits in the form of a microprocessor or central processing unit and may be formed as one or more Application-Specific Integrated Circuits (ASICs). Memory  29  may be any volatile or non-volatile memory or combination thereof such as, for example, random access memory (RAM), read only memory (ROM), flash memory and/or non-volatile RAM (NVRAM). Memory  29  may be in the form of a separate memory (e.g., RAM, ROM, and/or NVRAM), a hard drive, a CD or DVD drive, or any memory device convenient for use with controller  28 . Controller  28  may be, for example, a combined printer and scanner controller. 
     In the example embodiment illustrated, controller  28  communicates with print engine  30  via a communications link  50 . Controller  28  communicates with toner cartridge  100  and processing circuitry  44  thereon via a communications link  51 . Controller  28  communicates with media feed system  38  via a communications link  52 . Controller  28  communicates with scanner system  40  via a communications link  53 . User interface  36  is communicatively coupled to controller  28  via a communications link  54 . Controller  28  communicates with power supply  42  via a communications link  55 . Controller  28  processes print and scan data and operates print engine  30  during printing and scanner system  40  during scanning. Processing circuitry  44  may provide authentication functions, safety and operational interlocks, operating parameters and usage information related to toner cartridge  100 . Processing circuitry  44  includes a processor unit and associated electronic memory. As discussed above, the processor may include one or more integrated circuits in the form of a microprocessor or central processing unit and/or may include one or more Application-Specific Integrated Circuits (ASICs). The memory may be any volatile or non-volatile memory or combination thereof or any memory device convenient for use with processing circuitry  44 . 
     Computer  24 , which is optional, may be, for example, a personal computer, including memory  60 , such as RAM, ROM, and/or NVRAM, an input device  62 , such as a keyboard and/or a mouse, and a display monitor  64 . Computer  24  also includes a processor, input/output (I/O) interfaces, and may include at least one mass data storage device, such as a hard drive, a CD-ROM and/or a DVD unit (not shown). Computer  24  may also be a device capable of communicating with image forming device  22  other than a personal computer such as, for example, a tablet computer, a smartphone, or other electronic device. 
     In the example embodiment illustrated, computer  24  includes in its memory a software program including program instructions that function as an imaging driver  66 , e.g., printer/scanner driver software, for image forming device  22 . Imaging driver  66  is in communication with controller  28  of image forming device  22  via communications link  26 . Imaging driver  66  facilitates communication between image forming device  22  and computer  24 . One aspect of imaging driver  66  may be, for example, to provide formatted print data to image forming device  22 , and more particularly to print engine  30 , to print an image. Another aspect of imaging driver  66  may be, for example, to facilitate collection of scanned data from scanner system  40 . 
     In some circumstances, it may be desirable to operate image forming device  22  in a standalone mode. In the standalone mode, image forming device  22  is capable of functioning without computer  24 . Accordingly, all or a portion of imaging driver  66 , or a similar driver, may be located in controller  28  of image forming device  22  so as to accommodate printing and/or scanning functionality when operating in the standalone mode. 
     Print engine  30  includes laser scan unit (LSU)  31 , toner cartridge  100  and a fuser  37 , all mounted within image forming device  22 . Toner cartridge  100  is removably mounted in image forming device  22 . Power supply  42  provides an electrical voltage to various components of toner cartridge  100  via an electrical path  56 . Toner cartridge  100  includes a developer unit  102  that houses a toner reservoir and a toner development system. In one embodiment, the toner development system utilizes what is commonly referred to as a single component development system. In this embodiment, the toner development system includes a toner adder roll that provides toner from the toner reservoir to a developer roll. A doctor blade provides a metered uniform layer of toner on the surface of the developer roll. In another embodiment, the toner development system utilizes what is commonly referred to as a dual component development system. In this embodiment, toner in the toner reservoir of developer unit  102  is mixed with magnetic carrier beads. The magnetic carrier beads may be coated with a polymeric film to provide triboelectric properties to attract toner to the carrier beads as the toner and the magnetic carrier beads are mixed in the toner reservoir. In this embodiment, developer unit  102  includes a developer roll that attracts the magnetic carrier beads having toner thereon to the developer roll through the use of magnetic fields. Toner cartridge  100  also includes a photoconductor unit  104  that houses a charge roll, a photoconductive drum and a waste toner removal system. Although the example image forming device  22  illustrated in  FIG. 1  includes one toner cartridge, in the case of an image forming device configured to print in color, separate toner cartridges may be used for each toner color. For example, in one embodiment, the image forming device includes four toner cartridges, each toner cartridge containing a particular toner color (e.g., black, cyan, yellow and magenta) to permit color printing. 
       FIG. 2  shows toner cartridge  100  according to one example embodiment. Toner cartridge  100  includes an elongated housing  110  that includes walls forming a toner reservoir  112 . In the example embodiment illustrated, housing  110  extends along a longitudinal dimension  113  and includes a top  114 , a bottom  115 , a side  116  and a side  117  that extend between longitudinal ends  118 ,  119  ( FIG. 3 ) of housing  110 . In this embodiment, developer unit  102  is positioned along side  117  of housing  110  and photoconductor unit  104  is positioned along side  116  of housing  110 . 
     The electrophotographic printing process is well known in the art and, therefore, is described briefly herein. During a printing operation, a rotatable charge roll  122  of photoconductor unit  104  charges the surface of a rotatable photoconductive drum  120 . The charged surface of photoconductive drum  120  is then selectively exposed to a laser light source  124  from LSU  31  through a slit (not shown) in the top  114  of housing  110  to form an electrostatic latent image on photoconductive drum  120  corresponding to the image to be printed. Charged toner from developer unit  102  is picked up by the latent image on photoconductive drum  120  creating a toned image on the surface of photoconductive drum  120 . Charge roll  122  and photoconductive drum  120  are each electrically charged to a respective predetermined voltage by power supply  42  in order to achieve a desired voltage differential between the charged portions of the surface of photoconductive drum  120  and the portions of the surface of photoconductive drum  120  discharged by laser light source  124 . 
     Developer unit  102  includes toner reservoir  112  having toner stored therein and a rotatable developer roll  128  that supplies toner from toner reservoir  112  to photoconductive drum  120 . In the example embodiment illustrated, a rotatable toner adder roll  130  in developer unit  102  supplies toner from toner reservoir  112  to developer roll  128 . A doctor blade  132  disposed along developer roll  128  provides a substantially uniform layer of toner on developer roll  128  for transfer to photoconductive drum  120 . As developer roll  128  and photoconductive drum  120  rotate, toner particles are electrostatically transferred from developer roll  128  to the latent image on photoconductive drum  120  forming a toned image on the surface of photoconductive drum  120 . In one embodiment, developer roll  128  and photoconductive drum  120  rotate in opposite rotational directions such that their adjacent surfaces move in the same direction to facilitate the transfer of toner from developer roll  128  to photoconductive drum  120 . One or more movable toner agitators  134  may be provided in toner reservoir  112  to distribute the toner therein and to break up any clumped toner. Developer roll  128  and toner adder roll  130  are each electrically charged to a respective predetermined voltage by power supply  42  in order to attract toner from reservoir  112  to toner adder roll  130  and to electrostatically transfer toner from toner adder roll  130  to developer roll  128  and from developer roll  128  to the latent image on the surface of photoconductive drum  120 . Doctor blade  132  may also be electrically charged to a predetermined voltage by power supply  42  as desired. 
     The toned image is then transferred from photoconductive drum  120  to the print media (e.g., paper) either directly by photoconductive drum  120  or indirectly by an intermediate transfer member. In the example embodiment illustrated, the surface of photoconductive drum  120  is exposed from housing  110  along the bottom  115  of housing  110  where the toned image transfers from photoconductive drum  120  to the print media or intermediate transfer member. Fuser  37  ( FIG. 1 ) then fuses the toner to the print media. A cleaner blade  136  (or cleaner roll) of photoconductor unit  104  removes any residual toner adhering to photoconductive drum  120  after the toner is transferred from photoconductive drum  120  to the print media or intermediate transfer member. Waste toner from cleaner blade  136  may be held in a waste toner reservoir  138  in photoconductor unit  104  as illustrated or moved to a separate waste toner container. The cleaned surface of photoconductive drum  120  is then ready to be charged again and exposed to laser light source  124  to continue the printing cycle. 
       FIG. 3  shows the exterior of toner cartridge  100  according to one example embodiment. As shown, in this embodiment, developer unit  102  is positioned at side  117  of housing  110  and photoconductor unit  104  is positioned at side  116  of housing  110 . In the example embodiment illustrated, toner cartridge  100  includes a handle  111  positioned along side  116  and/or top  114  of housing  110  to assist the user with handling toner cartridge  100 . 
     In the example embodiment illustrated, a pair of drive couplers  140 ,  142  are exposed on an outer portion of housing  110  in position to receive rotational force from a corresponding drive system in image forming device  22  when toner cartridge  100  is installed in image forming device  22  to drive rotatable components of developer unit  102  and photoconductive drum  120 , respectively. The drive system in image forming device  22  includes one or more drive motors and a drive transmission from the drive motor(s) to a pair of drive couplers that mate with drive couplers  140 ,  142  of toner cartridge  100  when toner cartridge  100  is installed in image forming device  22 . In the example embodiment illustrated, drive couplers  140 ,  142  are each exposed on end  118  of housing  110 . Each drive coupler  140 ,  142  includes a rotational axis  141 ,  143 . In the example embodiment illustrated, drive couplers  140 ,  142  are each configured to mate with and receive rotational motion from the corresponding drive couplers in image forming device  22  at the axial ends of drive couplers  140 ,  142 . Drive coupler  140  is operatively connected (either directly or indirectly through one or more intermediate gears) to rotatable components of developer unit  102  including, for example, developer roll  128 , toner adder roll  130  and toner agitator  134 , to rotate developer roll  128 , toner adder roll  130  and toner agitator  134  upon receiving rotational force from the corresponding drive system in image forming device  22 . Drive coupler  142  is operatively connected (either directly or indirectly through one or more intermediate gears) to photoconductive drum  120  upon receiving rotational force from the corresponding drive system in image forming device  22 . In some embodiments, charge roll  122  is driven by friction contact between the surfaces of charge roll  122  and photoconductive drum  120 . In other embodiments, charge roll  122  is connected to drive coupler  142  by one or more gears. Any additional rotatable components of photoconductor unit  104 , e.g., one or more toner agitators or augers positioned in waste toner reservoir  138 , if present, may be connected to drive coupler  142  by one or more gears. 
       FIG. 4  shows developer unit  102  separated from photoconductor unit  104  with portions of developer unit  102  omitted to better illustrate the positions of developer roll  128  and toner agitator  134  within toner reservoir  112 . In  FIG. 5 , developer unit  102  is shown with toner agitator  134  in an exploded view. Developer unit  102  includes a body  160  having walls forming toner reservoir  112 . In the example embodiment illustrated, body  160  includes opposed first and second end walls  162 ,  164  each having a respective inner surface  162   a ,  164   a  forming a wall boundary of toner reservoir  112 . First and second drive mechanisms  168 ,  170  are positioned at respective outer surfaces  162   b ,  164   b  of first and second end walls  162 ,  164 , opposite inner surfaces  162   a ,  164   a . In the example embodiment illustrated, first drive mechanism  168  at outer surface  162   b  of first end wall  162  operatively connects drive coupler  140  to developer roll  128  and toner adder roll  130  such that first drive mechanism  168  rotates developer roll  128  and toner adder roll  130  when drive coupler  140  rotates. In this embodiment, second drive mechanism  170  at outer surface  164   b  of second end wall  164  operatively connects toner agitator  134  to first drive mechanism  168  via toner adder roll  130  such that second drive mechanism  170  rotates toner agitator  134  when first drive mechanism  168  rotates, as discussed in greater detail below. 
     In the example embodiment illustrated, toner agitator  134  has a shaft  135  that extends along the length of body  160 . First and second axial ends  135   a ,  135   b  of shaft  135  pass through aligned openings  166 ,  167  in first and second end walls  162 ,  164 , respectively. One or more agitators  137  extend from and rotate with shaft  135  to stir and move toner within toner reservoir  112 . Agitators  137  may include any suitable combination of paddles, prongs, stirrers, mixers, conveyors, etc. A drive gear  172  of second drive mechanism  170  is mounted on shaft  135  near second axial end  135   b  of shaft  135  such that rotation of drive gear  172  causes shaft  135  to rotate.  FIG. 6  shows second drive mechanism  170  in more detail. In the example embodiment illustrated, second drive mechanism  170  includes drive gear  172 , a compound idler gear  190  and a drive gear  182 . Drive gear  182  is mounted on a shaft  131  of toner adder roll  130 , which extends through a corresponding opening  133  in second end wall  164 , such that drive gear  182  rotates with toner adder roll  130 . Compound idler gear  190  is rotatably positioned at outer surface  164   b  of second end wall  164  and includes first and second sets of gear teeth gear  190   a ,  190   b  having different diameters. In the embodiment illustrated, first set of gear teeth  190   a  has a larger diameter than second set of gear teeth  190   b  and is positioned axially outboard of second set of gear teeth  190   b . First set of gear teeth  190   a  meshes with drive gear  182  of toner adder roll  130  and second set of gear teeth  190   b  meshes with drive gear  172  of toner agitator  134 . When toner adder roll  130  rotates upon being driven by first drive mechanism  168 , drive gear  182  also rotates transferring rotational force to compound idler gear  190  and drive gear  172  which, in turn, rotates toner agitator  134 . 
     With reference back to  FIG. 5 , outer surface  164   b  of second end wall  164  includes a boss  200  integrally formed therewith that protrudes outward along an axial dimension of toner agitator  134  at a location where second axial end  135   b  of shaft  135  passes through second end wall  164 . In the example embodiment illustrated, boss  200  has a center opening  201  formed about opening  167  through which second axial end  135   b  of shaft  135  passes. In the example embodiment illustrated, center opening  201  of boss  200  has a larger diameter than opening  167  in second end wall  164 . Opening  167  in second end wall  164  is sized to closely receive shaft  135  and center opening  201  of boss  200  is sized to receive an annular seal  220 . Seal  220  is positioned near second axial end  135   b  of shaft  135  and within center opening  201  of boss  200 . Seal  220  may be composed of any suitable flexible material. Seal  220  is positioned around an outer circumferential surface of shaft  135  and is sandwiched between an inner axial face  176  of drive gear  172  and outer surface  164   b  of second end wall  164  such that drive gear  172  compresses seal  220  against outer surface  164   b  of second end wall  164  when drive gear  172  is attached to shaft  135 . 
     When drive gear  172  is attached to second axial end  135   b  of shaft  135 , drive gear  172  encircles and is rotatably mounted on boss  200  so that drive gear  172  is free to rotate about boss  200 . Boss  200  provides a bearing surface against which drive gear  172  rotates. The arrangement between boss  200 , seal  220  and drive gear  172  provides a drive and sealing assembly for rotatably supporting drive gear  172  and for sealing the interface between shaft  135  and second end wall  164 . This configuration eliminates the need to include a separate bushing or bearing component at the outer surface  164   b  of second end wall  164  to rotatably support drive gear  172  thereby reducing manufacturing complexity, reducing cost and permitting a more compact design along the axial dimension of toner agitator  134 . 
       FIGS. 7A and 7B  are perspective views illustrating drive gear  172  and seal  220  separated from shaft  135  and boss  200 . In  FIG. 7B , a portion of second end wall  164  including boss  200  is cut away to better illustrate second axial end  135   b  of shaft  135 . In the example embodiment illustrated, drive gear  172  has outer and inner axial faces  174 ,  176 . A D-shaped hole  178  is formed through drive gear  172 . D-shaped hole  178  extends between outer and inner axial faces  174 ,  176  and is centered about a rotational axis of drive gear  172 . Second axial end  135   b  of shaft  135  has a corresponding D-shaped portion  150  that fits into D-shaped hole  178  on drive gear  172  such that shaft  135  is constrained to rotate with drive gear  172 . A catch  187  is positioned on outer axial face  174  of drive gear  172 . When drive gear  172  is attached to second axial end  135   b  of shaft  135  by inserting D-shaped portion  150  of shaft  135  into D-shaped hole  178  of drive gear  172 , catch  187  forms a snap fit engagement with a corresponding recess  152  on D-shaped portion  150  of shaft  135  to maintain axial alignment between drive gear  172  and shaft  135  and to prevent drive gear  172  from disengaging from shaft  135 . 
     Drive gear  172  includes a collar  180  extending axially inward relative to shaft  135  on inner axial face  176 . Collar  180  has an inner circumferential surface  181  and an outer circumferential surface  182 . Inner circumferential surface  181  defines a cavity  183  that is centered about D-shaped hole  178  and that has an end surface  185  formed on inner axial face  176 . In the example embodiment illustrated, boss  200  includes a generally cylindrical wall having an outer axial face  202 , an outer circumferential surface  204  and an inner circumferential surface  206  that defines center opening  201 . Outer circumferential surface  204  of boss  200  is sized to be received by cavity  183  of drive gear  172 . A ledge  208  that faces outward relative to an axial dimension of toner agitator  134  is formed along inner circumferential surface  206  of boss  200  within center opening  201 . One or more notches  210  are angularly spaced along inner circumferential surface  206  of boss  200  with each notch  210  extending from outer axial face  202  to ledge  208  of boss  200 . 
     Seal  220  includes a first axial end  221 , a second axial end  223  and a center opening  225  extending between first and second axial ends  221 ,  223 . In the example embodiment illustrated, a first axial end  222  of opening  225  at first axial end  221  of seal  220  has a smaller diameter than a second axial end  224  of opening  225  at second axial end  223  of seal  220 . First axial end  222  of opening  225  is sized to closely receive and contact an outer circumferential surface of shaft  135  when shaft  135  is passed through opening  225  of seal  220 . Second axial end  223  of seal  220  forms a contact surface that contacts inner axial face  176  (e.g., end surface  185  within cavity  183 ) of drive gear  172  when drive gear  172  is assembled onto shaft  135 . An outer ring  226  of seal  220  formed between first and second axial ends  221 ,  223  is sized to fit within center opening  201  of boss  200  and to contact ledge  208  within center opening  201  of boss  200 . One or more retention lugs  228  extend radially outward from outer ring  226  and are positioned to align with and be received by corresponding notches  210  within center opening  201  of boss  200  to prevent seal  220  from rotating relative to boss  200 . 
       FIG. 8  illustrates a side cross-sectional view of developer unit  102  with seal  220  and drive gear  172  assembled onto shaft  135  and boss  200 . In the example embodiment illustrated, shaft  135  is free to move axially relative to body  160  to a limited degree. In this embodiment, inward axial movement of shaft  135  is limited by contact between shaft  135  and inner surface  164   a  of second end wall  164 . In this embodiment, outward axial movement of shaft  135  is limited by contact between outer axial face  202  of boss  200  and inner axial face  176  (e.g., end surface  185  within cavity  183 ) of drive gear  172 . 
     In the example embodiment illustrated, seal  220  is mounted on shaft  135 , axially inward from D-shaped portion  150 , such that seal  220  is positioned within center opening  201  of boss  200 . First axial end  221  of seal  220  contacts an outer circumferential surface of shaft  135  thereby forming a sealing interface between seal  220  and shaft  135 . Drive gear  172  is slid along D-shaped portion  150  of shaft  135  such that catch  187  latches onto recess  152  on D-shaped portion  150  of shaft  135 . As drive gear  172  is assembled onto shaft  135 , second axial end  223  of seal  220  contacts end surface  185  of drive gear  172  pushing seal  220  toward second end wall  164 . The axial force provided by drive gear  172  against seal  220  presses outer ring  226  of seal  220  against ledge  208  within center opening  201  of boss  200  forming a sealing interface between outer ring  226  of seal  220  and ledge  208  of boss  200 . The sealing interfaces between first axial end  221  of seal  220  and the outer circumferential surface of shaft  135  and between outer ring  226  of seal  220  and ledge  208  of boss  200  prevent any toner that passes from reservoir  112  through second opening  167  in second end wall  164  from escaping developer unit  102 . 
     Further, in the example embodiment illustrated, drive gear  172  is mounted on boss  200  as drive gear  172  is pushed along shaft  135  toward second end wall  164  during assembly. When catch  187  of drive gear  172  latches onto recess  152  of shaft  135 , collar  180  of drive gear  172  encircles boss  200 . Inner circumferential surface  181  of collar  180  of drive gear  172  contacts at least a portion of outer circumferential surface  204  of boss  200  such that inner circumferential surface  181  of drive gear  172  bears against outer circumferential surface  204  of boss  200  to facilitate rotation of drive gear  172 . In this example embodiment, no separate bushing or bearing component is provided between second end wall  164  and drive gear  172 . Instead, bearing functionality at second axial end  135   b  of shaft  135  is achieved by forming boss  200  from the same second end wall  164  that directly bounds toner within toner reservoir  112  and by using an internal surface on drive gear  172  (i.e., inner circumferential surface  181  of collar  180 ) to bear against boss  200  to support rotation of drive gear  172 . Further, drive gear  172  itself retains and compresses seal  220  against second end wall  164  forming the seal interface at second axial end  135   b  of shaft  135  and does not rely on a separate bushing or bearing component to compress seal  220  against second end wall  164 . 
     With the above example embodiments, a bearingless drive gear  172  for toner agitator  134  is provided. Boss  200  formed on second end wall  164  provides the bearing for drive gear  172  without requiring a bearing element as an intermediate support. The configuration not only reduces the number of components to provide bearing and sealing functionality but also allows toner cartridge  100  to be designed in a more compact manner while achieving efficient bearing and seal performance. 
     Although the example embodiments discussed above have been described in the context of a drive and sealing assembly associated with a toner agitator of a toner cartridge, it will be appreciated that such a sealing assembly may be applied to other rotatable components in a toner cartridge and/or other assemblies of an image forming device, such as, for example, to developer roll  128  or toner adder roll  130 . 
     Further, although the example embodiment discussed above includes a single replaceable unit in the form of toner cartridge  100  for each toner color, it will be appreciated that the replaceable unit(s) of the image forming device may employ any suitable configuration as desired. For example, in one embodiment, the main toner supply for the image forming device is provided in a first replaceable unit and the developer unit and photoconductor unit are provided in a second replaceable unit. In another embodiment, the main toner supply for the image forming device and the developer unit are provided in a first replaceable unit and the photoconductor unit is provided in a second replaceable unit. Other configurations may be used as desired. 
     Further, it will be appreciated that the architecture and shape of toner cartridge  100  illustrated in  FIGS. 2-5  is merely intended to serve as an example. Those skilled in the art understand that toner cartridges, and other toner containers, may take many different shapes and configurations. 
     The foregoing description illustrates various aspects of the present disclosure. It is not intended to be exhaustive. Rather, it is chosen to illustrate the principles of the present disclosure and its practical application to enable one of ordinary skill in the art to utilize the present disclosure, including its various modifications that naturally follow. All modifications and variations are contemplated within the scope of the present disclosure as determined by the appended claims. Relatively apparent modifications include combining one or more features of various embodiments with features of other embodiments.