Abstract:
A toner cartridge having a pressure equalization system for equalizing a pressure differential between a toner reservoir in the toner cartridge and a toner sump developer unit containing ingested air utilizing a ducted shutter that opens and closes an exit port on the housing of the toner cartridge in combination with a passageway in fluid communication with the ducted shutter and the toner reservoir wherein, when the toner cartridge is mated with a developer unit of the imaging apparatus and the shutter is in the open position, exiting toner leaves the cartridge through the exit port and enters the developer unit while air entrained within the developer unit enters the toner reservoir via the exit port, the duct and the passageway equalizing pressure between the toner cartridge and the to developer unit.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
     The present application is related to U.S. patent application Ser. No. 13/340,830, filed Dec. 30, 2011, entitled “Imaging Apparatus With Pressure Equalization” and assigned to the assignee of the present application. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     None. 
     REFERENCE TO SEQUENTIAL LISTING, ETC. 
     None. 
     BACKGROUND 
     1. Field of the Disclosure 
     The present disclosure relates generally to toner cartridges used in electrophotographic imaging devices such as a printer or multifunction device having printing capability, and in particular to a pressure equalization system used for toner cartridges. 
     2. Description of the Related Art 
     In toner cartridge design, it is now common practice to separate the longer lived components from those having a shorter life. This has lead to having the longer lived developing components such as the developer roll, toner adder rolls, doctor blades, the foregoing are also referred to as a developing unit, photoconductive drums, cleaning and charge rollers and a waste bin to be in separate assemblies from the toner cartridge. The toner supply, which is consumed relatively quickly in comparison to the previously described components, is provided in a reservoir in a separate toner cartridge that mates with the developer unit. The toner cartridge has a reduced number of components and is often referred to as a toner bottle even though it is more than a mere bottle for holding toner. 
     To deliver the toner from the toner cartridge to the developer unit, an auger in the toner cartridge may be used to feed toner from the toner cartridge via an exit port on the toner cartridge into an entry port on the developer unit and into a second auger that disperses the toner within the developer unit. As the toner is drawn out of the cartridge unit, it is augured through a shutter used for sealing the exit port of the toner cartridge when it is not inserted in the imaging apparatus. 
     While moving toner through the restriction formed by the shutter, auger and exit port, the opening from the exit port into the toner reservoir in the toner cartridge is relatively air tight. A low pressure condition or vacuum-like condition is created in the toner cartridge as toner is removed as air cannot enter to fill the void. If the toner cartridge were viewed as being a pump supplying toner from the toner reservoir, this low pressure condition would be analogous to cavitation in a pump. 
     In the same manner, as toner is augured into the developer unit, it passes through another shutter used to prevent toner from escaping the developer when the cartridge is not installed in the printer. This opening restricts airflow, therefore, as toner is dispensed into the developer unit, air must be displaced and a positive pressure is created in the developer unit. Further, the rotation of the developer roll causes the developer unit to ingest air further increasing the positive pressure in the developer unit. Toner being delivered from the toner cartridge to the developer unit must travel against this positive pressure gradient. This causes a significant reduction in the flow rate of the toner which can lead to failures such as incorrect cartridge empty indications, developer packing, or developer unit starvation. 
     This described pressure differential between the toner cartridge and developer unit necessitated that a vent be used to equalize the pressure between the developer unit and the toner cartridge. Previous venting methods for the toner cartridge included having a vent hole through the toner cartridge into the toner reservoir. Labyrinth type vent plugs, vent plugs of a porous material, and even foam tape have been used to vent air into the toner cartridge while preventing toner from escaping the toner cartridge through the vent hole. However, these methods were not successful in equalizing the pressure between the developer unit and the toner cartridge as these vent plug designs and foams tended to become clogged with toner. Further, even with the vent plugs being clear and the toner cartridge no longer in a low pressure state, venting of the higher pressure air in the developer unit back into the toner cartridge was problematic due to the restriction caused by the shutter for the exit port of the toner cartridge still causing the aforementioned pressure differential to exist between the toner cartridge and the developer unit. 
     In other previous toner cartridge designs, the developer unit and cartridge unit were permanently mated together so there was open fluid communications between the developer unit and the toner reservoir so that the entire system would become pressurized due to the ingestion of air caused by the rotation of the developer roll. In some cases, an internal vent was provided within the permanently mated developer unit and toner reservoir. These cartridges vented the higher internal air pressure to the atmosphere. The vent was typically made out of a porous woven materials, such as GORTEX® or VERSAPORE®, or felt. These venting methods were all designed around the principle of letting air out of the cartridge while filtering and restricting toner particles from escaping. They also required the filter to be placed in a position on the cartridge that was not buried under toner. However, faster process speeds, larger toner loads, as well as separating the toner cartridge and developer unit make these methods inadequate. 
     To solve the pressure differential problem, it would be advantageous to have a pressure equalization system to give air a path to move from a high pressure developer unit to a low pressure toner cartridge through the exit port of the toner cartridge. It would be a further advantage to have such a ducting system be sealable to prevent toner from escaping the toner cartridge during shipping, storage, and when removed from the imaging apparatus. It would be a further advantage to be able to provide a high rate of toner delivery that helps avoid a number of previously mentioned toner delivery failures. 
     SUMMARY 
     A toner cartridge comprising a housing having a reservoir enclosed therein for holding a quantity of toner, the housing having an exit port in communication with the reservoir for receiving toner exiting the toner cartridge. A shutter mounted on the housing and moveable between a first position where the exit port is closed and a second position where the exit port is open allows toner to exit. The shutter has a duct therethrough, the duct having a first end in fluid communication with the exit port when the shutter is in the second position. A passageway is provided having a first end in fluid communication with a second end of the duct when the shutter is in the second position and a second end in fluid communication with the toner reservoir. When the toner cartridge is aligned with a developer unit of an imaging apparatus and the shutter is in the second position, exiting toner leaves the toner cartridge through the exit port and enters the developer unit while air entrained within the developer unit enters the toner reservoir via the exit port. The duct and the passageway allow the pressure between the toner cartridge and the developer unit to equalize. 
     A moveable cover may provided on the second end of the passageway and biased to close the second end of the passageway to prevent toner within the reservoir from entering the passageway, the moveable cover being openable by the air entering the reservoir from the developer unit. The moveable cover may comprise a reed valve. 
     In another form the passageway further comprises an open-sided channel formed in the housing enclosed by a resilient film strip. The film strip has a first portion and a second portion, the first portion having an adhesive for adhering the film strip to the housing and a second portion at the second end of the passageway forming the moveable cover. 
     In one form the shutter includes a drive portion and a hollow portion with the drive portion connectable to a lever for rotating the shutter between the first and second positions. The hollow portion extends from an inner end of the shutter toward an outer end of the shutter. The hollow portion has a first open end and a second closed end and an exit opening through a wall of the hollow portion adjacent the second closed end wherein exiting toner enters the first open end of the hollow cylindrical portion and exits through exit opening when the shutter is in the second position. The duct is positioned between the second closed end of the hollow cylindrical portion and the outer end of the shutter. A deflector rib positioned at the second closed end of the hollow cylindrical portion extends radially outwardly from the shutter to direct the exiting toner into the exit port and away from the first end of the duct. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above-mentioned and other features and advantages of the disclosed embodiments, and the manner of attaining them, will become more apparent and will be better understood by reference to the following description of the disclosed embodiments in conjunction with the accompanying drawings. 
         FIG. 1  is a block diagram of an example imaging system utilizing the imaging unit of the present invention. 
         FIG. 2  is an illustration of one embodiment of an imaging unit and a toner cartridge. 
         FIG. 3  is an illustration of the combination of a toner cartridge and a assembled developer unit embodying the present invention. 
         FIG. 4  is an illustration of a partially assembled developer unit shown with a partially assembled toner cartridge mounted thereon. 
         FIG. 5  is sectional view of the air flow path from the inlet port of the developer unit into the toner reservoir of the toner cartridge taken along line  5 - 5  in  FIG. 4 . 
         FIGS. 6 and 7  illustrate the channel for the air flow path within a lid of the toner cartridge along with one form of a reed valve. 
         FIG. 8  is an exploded view of the example shutter assembly of the toner cartridge shown in the open position. 
         FIG. 9  is a view of the assembled shutter assembly of  FIG. 8  shown in the closed position. 
         FIG. 10  is a sectional view of the shutter of  FIG. 8  taken along line  10 - 10  of  FIG. 8 . 
         FIG. 11  is a view of the toner exit port of the toner cartridge. 
         FIG. 12  is an exploded view of the example shutter assembly of the developer unit. 
         FIGS. 13 and 14  illustrate the shutter assembly of  FIG. 10  in a closed position and an open position within a cutaway view of the developer unit. 
         FIG. 15  is a view of the toner entry port of the developer unit. 
         FIG. 16  is a cutaway illustration of the exit port region of the toner cartridge and the inlet port region of the developer unit of an imaging unit showing the toner feed path and the air flow path therethrough. 
     
    
    
     DETAILED DESCRIPTION 
     It is to be understood that the present disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The present disclosure is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless limited otherwise, the terms “connected,” “coupled,” and “mounted,” and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings. In addition, the terms “connected” and “coupled” and variations thereof are not restricted to physical or mechanical connections or couplings. 
     Spatially relative terms such as “top”, “bottom”, “front”, “back”, “rear” and “side” “under”, “below”, “lower”, “over”, “upper”, and the like, are used for ease of description to explain the positioning of one element relative to a second element. These terms are generally used in reference to the position of an element in its intended working position within an imaging device. The terms “left” and “right” are as viewed with respect to the insertion direction of a unit into the imaging device. These terms are intended to encompass different orientations of the device in addition to different orientations than those depicted in the figures. Further, terms such as “first”, “second”, and the like, are also used to describe various elements, regions, sections, etc. and are also not intended to be limiting. Like terms refer to like elements throughout the description. 
     As used herein, the terms “having”, “containing”, “including”, “comprising”, and the like are open ended terms that indicate the presence of stated elements or features, but do not preclude additional elements or features. The articles “a”, “an” and “the” are intended to include the plural as well as the singular, unless the context clearly indicates otherwise. 
     The term “image” as used herein encompasses any printed or digital form of text, graphic, or combination thereof. The term “output” as used herein encompasses output from any printing device such as color and black-and-white copiers, color and black-and-white printers, and so-called “all-in-one devices” that incorporate multiple functions such as scanning, copying, and printing capabilities in one device. The term “button” as used herein means any component, whether a physical component or graphic user interface icon, that is engaged to initiate output. 
     Referring now to the drawings and particularly to  FIG. 1 , there is shown a diagrammatic depiction of an imaging system  20  embodying the present invention. As shown, imaging system  20  may include an imaging apparatus  22  and a computer  24 . Imaging apparatus  22  communicates with computer  24  via a communications link  26 . As used herein, the term “communications link” is used to generally refer to structure that facilitates electronic communication between multiple components, and may operate using wired or wireless technology and may include communications over the Internet. Imaging system  20  may be, for example, a customer imaging system, or alternatively, a development tool used in imaging apparatus design. 
     In the embodiment shown in  FIG. 1 , imaging apparatus  22  is shown as a multifunction machine that includes a controller  28 , a print engine  30 , a laser scan unit (LSU)  31 , an imaging unit  32 , a cleaner unit  33 , a developer unit  34 , a toner cartridge  35 , a user interface  36 , a media feed system  38  and media input tray  39  and a scanner system  40 . Imaging apparatus  22  may communicate with computer  24  via a standard communication protocol, such as for example, universal serial bus (USB), Ethernet or IEEE 802.xx. A multifunction machine is also sometimes referred to in the art as an all-in-one (AIO) unit. Those skilled in the art will recognize that imaging apparatus  22  may be, for example, an electrophotographic printer/copier including an integrated scanner system  40 ; or a standalone scanner system  40 . 
     Controller  28  includes a processor unit and associated memory  29 , and may be formed as one or more Application Specific Integrated Circuits (ASICs). Memory  29  may be any volatile on non-volatile memory or combinations thereof such as, for example, random access memory (RAM), read only memory (ROM), flash memory, and/or non-volatile RAM (NVRAM). Alternatively, memory  29  may be in the form of a separate electronic 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 present embodiment, controller  28  communicates with print engine  30  via a communications link  50 . Controller  28  communicates with imaging unit  32  and processing circuitry  44  thereon via a communications link  51 . Controller  28  communicates with toner cartridge  35  and processing circuitry  45  therein via a communications link  52 . Controller  28  communicates with media feed system  38  via a communications link  53 . Controller  28  communicates with scanner system  40  via a communications link  54 . User interface  36  is communicatively coupled to controller  28  via a communications link  55 . Processing circuits  44 ,  45  may provide authentication functions, safety and operational interlocks, operating parameters and usage information related to imaging unit  32  and toner cartridge  35 , respectively. Controller  28  serves to process print data and to operate print engine  30  during printing, as well as to operate scanner system  40  and process data obtained via scanner system  40 . 
     Computer  24 , which may be optional, may be, for example, a personal computer, network server, tablet computer, smartphone or other hand-held electronic device, including memory  60 , such as volatile and/or non-volatile memory, input device  62 , such as a keyboard, and a display, such as monitor  64 . Computer  24  further 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  includes in its memory a software program including program instructions that function as an imaging driver  66 , e.g., printer/scanner driver software, for imaging apparatus  22 . Imaging driver  66  is in communication with controller  28  of imaging apparatus  22  via communications link  26 . Imaging driver  66  facilitates communication between imaging apparatus  22  and computer  24 . One aspect of imaging driver  66  may be, for example, to provide formatted print data to imaging apparatus  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. 
     In some circumstances, it may be desirable to operate imaging apparatus  22  in a standalone mode. In the standalone mode, imaging apparatus  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 imaging apparatus  22  so as to accommodate printing and scanning functionality when operating in the standalone mode. 
     Print engine  30  may include a laser scan unit (LSU)  31 , an imaging unit  32 , a toner cartridge  35 , and a fuser  37 , all mounting within imaging apparatus  22 . The imaging unit  32  further includes a cleaner unit  33  housing a waste toner removal system and a photoconductive drum, and a developer unit  34  that are removably mounted within imaging unit  32 . In one embodiment the cleaner unit  33  and developer unit  34  are assembled together and installed into a frame forming the imaging unit  32 . The toner cartridge  35  is then installed in the frame in a mating relation with the developer unit  34 . Laser scan unit  31  creates a latent image on the photoconductive drum in the cleaner unit  33 . The developer unit  34  has a toner sump containing toner which is transferred to the latent image on the photoconductive drum to create a toned image. The toned image is subsequently transferred to a media sheet received in the imaging unit  32  from media input tray  39  for printing. Toner remnants are removed from the photoconductive drum by the waste toner removal system. The toner image is bonded to the media sheet in the fuser  37  and then sent to an output location or to one or more finishing options such as a duplexer, a stapler or hole punch. 
     The toner cartridge  35  removably mates with the developer unit  34  in imaging unit  32 . An exit port on the toner cartridge  35  communicates with an inlet port on the developer unit  34  allowing toner to be periodically transferred from the toner cartridge  35  to resupply the toner sump in the developer unit  34 . 
     Referring now to  FIG. 2 , an example embodiment of the imaging unit  100  is shown. Imaging unit  100 , as illustrated, comprises developer unit  400 , a cleaner unit  600  and a frame  800 . Developer unit  400  and cleaner unit  600  are assembled together with frame  800 , with toner cartridge  200  being slidably received on frame  800 . The imaging unit  100   200  is initially slidably received in the imaging apparatus  22 . The toner cartridge  200  is then guided by frame  800  into operative engagement with the developer unit  400 . This arrangement allows the toner cartridge  200  to be removed and reinserted easily when replacing an empty toner cartridge without having to remove imaging unit  100 . Should a media jam occur beneath the imaging unit  100 , the toner cartridge  200  and imaging unit  100  may be readily removed to allow access to the media jam. The developer unit  400 , cleaning unit  600  and frame  800  may also be readily removed and reinserted when required, however, this would normally occur with less frequency than the removal and reinsertion of toner cartridge  200 . 
     In  FIGS. 3-5 , an example embodiment of the toner cartridge  200  and developer unit  400  is shown. For simplicity, cleaner unit  600  and frame  800  are not shown. The large arrow shown in  FIG. 3  indicates the insertion direction of the cartridge  200  into the frame  800  where it mates with developer unit  400  of the imaging unit  100 . The arrow also points toward what is termed the “front” of these various elements. Toner cartridge  200  comprises a housing  202  having a reservoir  204  enclosed therein (see  FIG. 5 ) for holding a quantity of toner. Housing  202  may be viewed as having a top or lid  206  mounted on a base  208 . Base  208  includes first and second side walls  210 ,  212 , connected to adjoining front and rear walls  214 ,  216 . Top  206  may be ultrasonically welded to base  208  forming reservoir  204 . First and second end caps  218 ,  220  are also mounted to housing  202  and include guides  222  to assist with supporting and inserting of toner cartridge for mating with developer unit  400 . First and second end caps  218 ,  220  may be snap fitted into place or attached by screws or other forms of fasteners. Guides  222  travel in channels provided within the housing of the imaging apparatus. Guides  226  may also be provided on base  208  to assist with insertion and removal of toner cartridge  200 . A handle  224  may be provided on top  206  to assist with insertion and removal of toner cartridge  200  from the imaging unit  100 . A fill port  225  is provided on second side wall  212  and is used to fill toner cartridge  200  with toner. After filling, fill port  225  would be closed by a plug or cap. 
     Various drive gears are housed within a space formed between first end cap  218  and first side wall  210  with main interface gear  228  being visible. Various interlocks and linkages may also be housed within the space formed between second end cap  220  and second side wall  212 . Mounting structures  229  may be provided on the exterior surfaces of first and second side walls  210 ,  212  for use with the interlocks and linkages. Main interface gear  228  engages with a drive system within imaging apparatus  22  which provides torque to main interface gear  228 . A paddle is rotatably mounted within toner reservoir  204  with first and second ends of a drive shaft of the paddle extending through aligned openings  244  in the first and second side walls  210 ,  212 , respectively. A drive gear is provided on the first end of the drive shaft of the paddle and engages with main interface gear  228  either directly or via one or more intermediate gears. First side wall  210  may also be termed the “drive” or “driven” side of toner cartridge  200 . 
     Referring to  FIG. 16 , an auger  230  having first and second ends  232 ,  234 , and a spiral screw flight  236  is received within a channel  250  extending along the width of front wall  214  between the first and second side walls  210 ,  212 . In one embodiment channel  250  is positioned above the axis of rotation of the drive shaft of the paddle. Channel  250  may be integrally molded as part of front wall  214  or be formed as a separate component that is attached to front wall  214 . Channel  250  is generally horizontal in orientation along with toner cartridge  200  when toner cartridge  200  is installed in imaging unit  100 . First end  232  of the auger  230  extends through first side wall  210  and a drive gear  238  is provided which engages with main interface gear  228  either directly or via one of more intermediate gears. A bushing  240  is provided where the first end  232  of auger  230  passes through first side wall  210 . A similar bushing may be provided on each of the ends of the paddle where they pass through the first and second side walls  210 ,  212 . Shutter assembly  300  is provided on the front wall  214  of housing  202  adjacent side wall  212  at one end of channel  250 . 
     Channel  250  comprises an open portion  252  and an enclosed portion  254 . Open portion  252  is open to the toner reservoir  204  and extends from the first side wall  210  toward the second end  234  of auger  230 . Enclosed portion  254  of channel  250  extends from the second side wall  212  and encloses a shutter  302  of shutter assembly  300  and the second end  234  of the auger  230 . The paddle, as it rotates, delivers toner from the toner reservoir  204  into the first portion  252  of channel  250 . Auger  230  is rotated via drive gear  238  to deliver toner received in channel  250  to the shutter  302  which is housed in the enclosed portion  254  of channel  250 . An exit port  256  is provided through the wall  258  forming the enclosed portion  254  of channel  250 . Shutter  302  rotates between a first position where it closes exit port  256  and a second position where exit port  256  is open. As illustrated (see also  FIG. 11 ) exit port  256  is disposed at the bottom of channel  250  so that gravity will assist in having toner exit through exit port  256 . 
     As shown in  FIGS. 5-7 , a passageway  260 , separate from channel  250 , is provided in the housing  202  from the shutter assembly  300  to the toner reservoir  204 . In  FIG. 5  shutter assembly  300  has not quite reached the fully opened or second position. As illustrated, passageway  260  extends between shutter assembly  300  to about the apex of the lid  206 . A first end  262  of passageway is in fluid communication with the enclosed portion  254  of channel  250  while a second end  264  of passageway  260  is in fluid communication with reservoir  204  and disposed above the toner contained within the reservoir  204  to reduce possible blockage of the second end  264  of passageway  260  by the toner. Passageway  260  is routed away from the path along which toner is delivered so that it will not become blocked by toner exiting toner cartridge  200 . In one form, passageway  260  is formed by an open-sided channel  266  provided on the interior surface  242  of top  206 . Channel  266  is enclosed by a resilient film  270  such as MYLAR®. Film  270  has two portions, a first portion  272  having adhesive thereon for attaching film  270  to interior surface  242  to enclose channel  266 , and a second portion  274  that is biased to close the second end  264  of passageway  260  but is movable to allow air traveling along passageway  260  from developer unit  400  to enter into toner reservoir  204 . The resilience of film  270  provides the biasing force for second portion  274 . Second portion  274  forms a moveable cover or a one way reed valve at the second end  264  of passage  260 . The biased-closed moveable cover  274  or reed valve  274  prevents the entry of toner into the second end  264  of passageway  260  while allowing air to enter the toner reservoir  204 . Passageway  260  may also be formed from a tube provided on the interior surface  242  with a reed valve or moveable cover  274  placed on second end  264 . 
     An example shutter assembly  300  for the toner cartridge  200  is shown in  FIGS. 8-11 . Shutter assembly  300  includes a shutter  302 , a retainer  304  and a lever  306 . In general, lever  306  is used to move shutter  302  between a first position where the exit port  256  is closed to channel  250  and a second position where the exit port  256  is open to channel  250 . A linkage (not shown) housed in second end cap  220  actuates lever  306  to move shutter  302  between the first and second positions during insertion and removal of toner cartridge  200 . A stop  310  is provided on one end of the shutter  302 , as shown, on drive portion  312 . Stop  310  travels in a channel provided in retainer  304 . The length of the channel in retainer  304  limits the travel of shutter  302  to between the first and second positions. Other forms of travel stops and other locations for the stop may be used as is known in the art. 
     In an example embodiment shutter  302  is generally cylindrical. Shutter  302  has a drive portion  312  and a hollow portion  314 . Shutter  302  is inserted into the enclosed portion  254  of channel  250  aligning the hollow portion  314  of shutter  302  with the second end  234  of auger  230 . Shutter  302  is rotatable within enclosed portion  254  of channel  250 . Drive portion  312  passes through an opening  316  in retainer  304  and is rotatable within opening  316 . Fasteners are inserted through openings  318  in retainer  304  and are received in corresponding openings in housing  202  rotatably securing shutter  302  in housing  202 . Drive portion  312  has one or more keys  320  that are received into corresponding one or more keyways  324  in opening  322  of lever  306  to ensure proper orientation of lever  306  with shutter  302 . Another fastener  308 , such as a screw, passes through openings  322 ,  316  and is received in opening  326  provided on the end of drive portion  312  securing lever  306  to shutter  302 . A connection pin  325  is provided at the distal end of lever  306  for attaching a drive linkage used for operating of lever  306 . It will be realized that alternatively one or more keys may be provided on lever  306  and be received in corresponding one or more keyways provided in drive portion  312  of shutter  302 . Other forms of fasteners may also be used. 
     Hollow portion  314  extends from an inner end  328  of the shutter  302  toward an outer end  330  of the shutter  302  and has a open end  332  and a closed end  334 . Open end  332  and hollow portion  314  are sized to rotatably receive the second end  234  of auger  230  and provide support for auger  230 . Exit opening  336  is provided through a wall  333  of hollow portion  314 . A channel  337  is formed in shutter  302  between the open end  332  and exit opening  336  through which exiting toner passes on its way to the exit port  256 . When the shutter  302  is in its second or open position, rotation of auger  230  pushes toner in channel  250  through channel  337  and out exit opening  336  where it falls through exit port  256 .  FIG. 8  illustrates the position of shutter  302  when in its second position in toner cartridge  200  while  FIG. 9  illustrates the position of shutter  302  when in its first position in toner cartridge  200 . 
     A duct  340  having first and second ends  342 ,  344  passes through shutter  302  and is disposed within drive portion  312 . First end  342  of duct  340  is positioned near exit opening  336 . Example duct  340  is shown routed through shutter  302  along a diameter thereof and does not intersect with channel  337 . However, other routings for duct  340  may be used through drive portion  312  of shutter  302 . In one embodiment a deflection rib  338  is disposed near closed end  334  of hollow portion  314 . Deflection rib  338  directs toner leaving exit opening  336  away from first end  342  of duct  340  and into exit port  256 . Deflection rib  338  may extend into exit port  256 . Deflection rib  338  helps to block exiting toner leaving exit opening  336  from entering duct  340 . 
     A foam seal  350  is shown in  FIG. 10  wrapped around shutter  302 . Foam seal  350  has openings  352 ,  354  therethrough. Opening  352  is disposed about both the first end  342  of duct  340  and exit opening  336  while opening  354  is disposed about second end  344  of duct  340 . Foam seal  350  is used to seal the space between shutter  302  and the enclosed portion  254  of channel  250  to prevent the leakage of toner around exit port  256 . As is known in the art, the ends of foam seal  350  may use wavy or irregular edges where they join together so as to inhibit toner leakage through this area. 
     Referring to  FIGS. 3-5 ,  13 ,  14  and  16 , the developer unit  400 , illustrated in a partially assembled state in  FIGS. 4 and 5 , comprises a housing  402  having a toner sump  404  formed by a rear wall  406 , first and second side walls  408 ,  410  and bottom  412 . The cleaner unit  600 , which would be in front of the developer unit  400 , and frame  800  are not shown. A developer roll  420 , doctor blade  422  and toner adder roll are mounted between first and second side walls  408 ,  410 . The doctor blade  422  provides a metered uniform layer of toner on the surface of developer roll  420 . The developer roll  420  and doctor blade  422  help enclose the toner sump  404 . A drive gear  424  is provided on one end of the developer roll  420 . The toner adder roll, which is behind the developer roll  420 , also has a driver gear on one end. Drive gear  426  mounted on first side wall  408 . An auger  430  having first and second ends  432 ,  434 , and a spiral screw flight  436  is received within a channel  450  extending along the width of and near the top of rear wall  408 . First end  432  of the auger  430  extends through first side wall  408  and a drive gear  438  is provided thereon which engages with driver gear  426  either directly or via one of more intermediate gears to rotate auger  430 . Drive gear  426  receives torque from the imaging apparatus and in turn drives drive gears  424 ,  438 , as well as the toner adder roll. 
     Channel  450  comprises an open portion  452  and an enclosed portion  454 . Open portion  452  is open to the toner sump  404  and extends from the first side wall  408  toward the second end  434  of auger  430 . Enclosed portion  454  of channel  450  extends from the second side wall  410  and encloses a shutter  502  of shutter assembly  500  and the second end  434  of the auger  430 . A slot  455  is provided in the enclosed portion. Auger  430  is rotated via drive gear  438  to deliver toner received in shutter  502  into the open portion  452  of channel  450  and then into toner sump  404 . A toner entry port  456  is provided through the wall  458  of channel  450  forming the enclosed portion  454  of channel  450 . Shutter  502  rotates between a first position where it closes entry port  456  and a second position where entry port  456  is open. As illustrated (see  FIG. 15 ) entry port  456  is disposed at the top of channel  450  so that gravity will assist in having toner drop through entry port  456 . 
     Entry port  456  for toner (see  FIG. 16 ) on housing  402  aligns with the exit port  256  of toner cartridge  200  when toner cartridge  200  is installed in frame  800 . In one example form, entry port  456  is larger in area than exit port  256  to prevent bridging by the toner exiting toner cartridge  200  and entering developer unit  400 . Below toner entry port  456 , the entering toner passes through shutter  502  of shutter assembly  500  and into channel  450 . The second end  434  of auger  430  extends into shutter assembly  500  to feed the entering toner along channel  450  and into toner sump  404 . An arcuate member  460  having a semicylindrical portion extending along its width is attached to rear wall  406  between first side wall  408  and the enclosed portion  454  of channel  450  forming the open portion  452  of channel  450  therebetween. Arcuate member  460  has a plurality of spaced openings  462  in the semi-cylindrical portion or what is the bottom of channel  450  to allow for toner received into channel  450  to be distributed along the length of the channel and into toner sump  404  as to auger  430  is rotated. The open portion  452  of channel  450  may also be formed into rear wall  406  in a similar fashion to channel  250  in toner cartridge  200 . Channel  450  is disposed above the toner contained within toner sump  404  allowing the entering toner to drop into the toner sump  404 . 
     Referring now to  FIGS. 12-15 , the example shutter assembly  500  includes a shutter  502 , a retainer  504  and a lever  506 . Shutter assembly  500  operates in a manner similar to shutter assembly  300 . In general, lever  506  is used to move shutter  502  between a first position where the toner entry port  456  is closed to channel  450  and a second position where the inlet port  546  is open to channel  450 . A protrusion  280  (see  FIGS. 3 ,  11 ) on housing  202  actuates lever  506  to move shutter  502  between the first and second positions during insertion and removal of toner cartridge  200 . A stop  510  (see  FIG. 15 ) is provided on one end of the shutter  502 , as shown, on drive portion  512 . Stop  510  travels in a channel provided in retainer  504 . The length of the channel in retainer  504  limits the travel of shutter  502  to between the first and second positions. Other forms of travels stops and other locations for the stop may be used as is known in the art. 
     Example embodiment shutter  502  is generally cylindrical. Shutter  502  has a drive portion  512  and a hollow portion  514 . Shutter  502  is inserted into the enclosed portion  454  of channel  450  aligning the hollow portion  514  of shutter  502  with the second end  434  of auger  430 . Shutter  502  is rotatable within enclosed portion  454  of channel  450 . Drive portion  512  passes through an opening  516  in retainer  504  and is rotatable within opening  516 . Fasteners, such as screws, are inserted through openings  518  in retainer  504  and are received in corresponding openings in housing  402  rotatably and axially securing shutter  502  in housing  402 . Drive portion  512  has one or more keys  520  that are received into corresponding one or more keyways  524  in opening  522  of lever  506  to ensure proper orientation of lever  506  with shutter  502 . Another fastener  508 , such as a screw, passes through opening  522  and is received in opening  526  provided on the end of drive portion  512  securing lever  506  to shutter  502 . It will be realized that alternatively one of more keys may be provided on lever  506  and be received in corresponding one or more keyways provided in drive portion  512  of shutter  502 . Also other forms of fasteners may also be used. 
     Hollow portion  514  extends from an inner end  528  of the shutter  502  toward an outer end  530  of the shutter  502  and has a open end  532  and a closed end  534 . Open end  532  and hollow portion  514  are sized to rotatably receive the second end  434  of auger  430  and provide support for auger  430 . Entry opening  536  is provided through a wall  538  of hollow portion  514 . Example entry opening  536  is larger in area than exit opening  336  in shutter  302 . Example entry opening  536  is illustrated as having to two or more radially offset or stepped sections  536 A,  536 B that are joined together to form entry opening  536 . This arrangement of offset or stepped sections helps to prevent bridging by the entering toner and to ensure that an air flow path is maintained between the toner sump  404  and the toner entry port  456 . A channel  537  is formed in shutter  502  between the open end  532  and exit opening  536  through which entering toner passes on its way to channel  450 . When the shutter  502  is in its second or open position, rotation of auger  430  pulls toner from channel  537  and out open end  532  and into channel  450 . With the shutter in its first or closed position, the shutter blocks slot  455  and the second end  434  of auger  430  and toner block the open end  532  of shutter  502 .  FIG. 13  illustrates the position of shutter  502  when in its first position or closed position in developer unit  400 . When in the second or open position, stepped section  536 B is aligned with slot  455  of the enclosed portion  454  of the channel  450  allowing entrapped air to follow the AFP and exit the developer housing  402  through shutter  502  and toner entry port  456 .  FIG. 14  illustrates the position of shutter  502  when in its second position or open position. 
     A foam seal, similar to form seal  350 , is wrapped around shutter  502 . Foam seal has an opening therethrough disposed about entry opening  536 . Foam seal is used to seal the space between shutter  502  and the enclosed portion  454  of channel  450  to prevent the leakage of toner around entry port  456 . As is known in the art, the ends of foam seal may use curvilinear or wavy edges where they join together creating a labyrinth joint to inhibit toner leakage through this area of the foam seal  550 . 
     In one form, the drive and hollow portions of shutters  302 ,  502  taper inwardly from their respective outer ends  330 ,  530  towards their respective inner ends  328 ,  528 . 
       FIG. 16  illustrates the toner flow path, shown as the solid arrow TFP, and air flow path, shown as the dashed arrow AFP, between the toner cartridge  200  and developer unit  400 . The air flow path AFP is also shown in  FIG. 5 . A portion of the air flow path AFP is also shown in  FIG. 14 . The toner exit port  256  is aligned with toner entry port  456  when the toner cartridge  200  is installed in imaging unit  100 . Both shutter assemblies  300 ,  500  are in their respective second or open positions. A foam seal  480  is provided on toner entry port  456  between toner entry port  456  and exit port  256 . The toner flow path is from toner reservoir  204  into channel  250  through channel  337 , exit opening  336  and out exit port  256  and into entry port  456  and into entry opening  536  through channel  537 , out open end  532  into channel  450  into toner sump  404  of developer unit  400 . The air flow path is from toner sump  404  of developer unit  400  into open end  532 , entry opening  536  and or channel  537  of shutter  502  and out entry port  456  and into exit port  256  and into and through duct  340  of shutter  302  into passageway  260  and out reed valve  274 . The toner in the hollow portion  314  of shutter  302  and channel  250  blocks the entry of air into the reservoir  204 . The portion of the air flow path extending from exit port  256  through reed valve  274  may be termed the toner cartridge airway. 
     The portion of the air flow path from the toner sump  404  to entry port  456  may be termed the developer unit airway. By activating the toner cartridge airway, a vent is opened that allows air in the developer unit  400  to bypass the airflow restrictions in shutter assembly  300  and flow into the top of the toner cartridge  200 . The higher pressure air in the developer unit  400  exits via the developer unit airway and enters toner cartridge  200  via the toner cartridge airway. This eliminates the vacuum or low pressure region in the toner reservoir  204  of toner cartridge  200  as toner is removed, allows for maximum toner flow from the exit port  256 , and pressure equalization between the toner cartridge  200  and developer unit  400 . The positioning of shutter assembly  500  in channel  450  and the positioning channel  450  and entry port  456  above the level of the toner contained within toner sump  404  helps to ensure that the developer unit airway remains clear. 
     To prevent a user from having to intervene with activating the toner cartridge airway, the passageway  260  is routed through the duct  340  of cartridge shutter  302 . One advantage of this routing is that if the toner cartridge airway runs through shutter  302  of toner cartridge  200 , when the toner cartridge  200  is removed, the toner therein is double sealed by the reed valve  274  and shutter  302 . This prevents toner from leaking out of the cartridge during drop testing or shipping. Another advantage is that by having the toner cartridge airway run through the shutter  302  and exit port  256  locates the duct  340  directly over the developer unit toner entry port  456 . This connects the duct  340  and passageway  260  to the developer unit  400  using preexisting connections, eliminating user intervention and eliminating the need to have a separate airway opening in each of the toner cartridge  200  and developer unit  400  unit which may provide another path for toner leakage. When the user installs the toner cartridge  200  into the imaging unit  100 , a linkage is moved by the toner cartridge  200  actuating shutter assembly  500  and moving shutter  502  into its second or open position. When the toner cartridge  200  is fully seated in the imaging unit  100 , a door over that toner cartridge  200  can then be closed by a user and a rod or plunger on the interior of the door actuates shutter assembly  300  and moving shutter  302  into its second or open position. At this time the toner cartridge airway and the developer unit airway are activated with both shutter assemblies  300 ,  500  being in their respective open positions. 
     The foregoing description of several methods and an embodiment of the invention has been presented for purposes of illustration. It is not intended to be exhaustive or to limit the invention to the precise steps and/or forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. It is intended that the scope of the invention be defined by the claims appended hereto.