Venting system for a toner cartridge for use with an image forming device

[0001] This application claims priority to U.S. Provisional Patent Application Ser. No. 61/834,903, filed Jun. 14, 2013, entitled “Venting System for a Toner Cartridge for Use with an Image Forming Device,” the content of which is hereby incorporated by reference in its entirety.

[0002] 1. Field of the Disclosure

[0003] The present disclosure relates generally to image forming devices and more particularly to a venting system for a toner cartridge for use with an image forming device.

[0004] 2. Description of the Related Art

[0005] In order to reduce the premature replacement of components traditionally housed within a toner cartridge for an image forming device, toner cartridge manufacturers have begun to separate components having a longer life from those having a shorter life into separate replaceable units. Relatively longer life components are positioned in one replaceable unit (an imaging unit). The image forming device's toner supply, which is consumed relatively quickly in comparison with the components housed in the imaging unit, is provided in a reservoir in a separate replaceable unit in the form of a toner cartridge that feeds toner to the imaging unit. In this configuration, the number of components housed in the toner cartridge is reduced in comparison with traditional toner cartridges.

[0006] Toner is moved from a toner reservoir in the toner cartridge through an outlet port on the toner cartridge into an inlet port on the corresponding imaging unit. A relatively air tight seal is often desired around the outlet port of the toner cartridge in order to prevent toner from leaking as it moves from the toner cartridge to the imaging unit. As toner is fed from the toner cartridge, a low pressure or vacuum-like condition may be created in the toner cartridge as toner is removed and air cannot enter to fill the void. Further, as toner enters the imaging unit, air may be displaced creating a high pressure condition in a toner reservoir of the imaging unit. If the pressure gradient between the reservoirs of the imaging unit and the toner cartridge is too large, toner flow from the toner cartridge to the imaging unit may be restricted causing the toner flow rate to become inconsistent and unpredictable. This can lead to failures such as incorrect cartridge empty determination or starvation of the imaging unit. Accordingly, a venting system that aids toner flow from the toner cartridge to the imaging unit is desired.

[0007] A toner cartridge for an electrophotographic image forming device according to one example embodiment includes a housing having a reservoir for storing toner. An outlet port is positioned on the housing for transferring toner out of the toner cartridge. A venting system includes a first vent positioned to introduce air from outside the housing into the reservoir and a second vent positioned to introduce air received at the outlet port into the reservoir. The venting system maintains an air pressure in the reservoir at the greater of a pressure of the air from outside the housing and the air received at the outlet port.

[0008] A toner cartridge for an electrophotographic image forming device according to another example embodiment includes a housing having a reservoir for storing toner. An outlet port is positioned on the housing for transferring toner out of the toner cartridge. An auger is positioned above the outlet port for moving toner from the reservoir to the outlet port. A vent includes an inlet opening positioned on an inner side of a wall of the housing next to the auger adjacent the outlet port for receiving air at the outlet port and an outlet opening positioned on the inner side of the wall of the housing in an upper portion of the reservoir for exiting the received air into the upper portion of the reservoir. A duct forms an air pathway connecting the inlet opening and the outlet opening. A one-way valve permits airflow into the upper portion of the reservoir from the vent and restricts toner from exiting the reservoir through the vent.

[0025] 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 to their equivalents.

[0026] Referring now to the drawings and more 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 100 and a computer 30. Image forming device 100 communicates with computer 30 via a communications link 40. 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.

[0027] In the example embodiment shown in FIG. 1, image forming device 100 is a multifunction machine (sometimes referred to as an all-in-one (AIO) device) that includes a controller 102, a print engine 110, a laser scan unit (LSU) 112, one or more toner bottles or cartridges 200, one or more imaging units 300, a fuser 120, a user interface 104, a media feed system 130 and media input tray 140 and a scanner system 150. Image forming device 100 may communicate with computer 30 via a standard communication protocol, such as, for example, universal serial bus (USB), Ethernet or IEEE 802.xx. Image forming device 100 may be, for example, an electrophotographic printer/copier including an integrated scanner system 150 or a standalone electrophotographic printer.

[0028] Controller 102 includes a processor unit and associated memory 103 and may be formed as one or more Application Specific Integrated Circuits (ASICs). Memory 103 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). Alternatively, memory 103 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 102. Controller 102 may be, for example, a combined printer and scanner controller.

[0029] In the example embodiment illustrated, controller 102 communicates with print engine 110 via a communications link 160. Controller 102 communicates with imaging unit(s) 300 and processing circuitry 301 on each imaging unit 300 via communications link(s) 161. Controller 102 communicates with toner cartridge(s) 200 and processing circuitry 201 on each toner cartridge 200 via communications link(s) 162. Controller 102 communicates with fuser 120 and processing circuitry 121 thereon via a communications link 163. Controller 102 communicates with media feed system 130 via a communications link 164. Controller 102 communicates with scanner system 150 via a communications link 165. User interface 104 is communicatively coupled to controller 102 via a communications link 166. Processing circuitry 121, 201, 301 may include a processor and associated memory such as RAM, ROM, and/or NVRAM and may provide authentication functions, safety and operational interlocks, operating parameters and usage information related to fuser 120, toner cartridge(s) 200 and imaging units 300, respectively. Controller 102 processes print and scan data and operates print engine 110 during printing and scanner system 150 during scanning.

[0030] Computer 30, which is optional, may be, for example, a personal computer, including memory 32, such as RAM, ROM, and/or NVRAM, an input device 34, such as a keyboard and/or a mouse, and a display monitor 36. Computer 30 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 30 may also be a device capable of communicating with image forming device 100 other than a personal computer such as, for example, a tablet computer, a smartphone, or other electronic device.

[0031] In the example embodiment illustrated, computer 30 includes in its memory a software program including program instructions that function as an imaging driver 38, e.g., printer/scanner driver software, for image forming device 100. Imaging driver 38 is in communication with controller 102 of image forming device 100 via communications link 40. Imaging driver 38 facilitates communication between image forming device 100 and computer 30. One aspect of imaging driver 38 may be, for example, to provide formatted print data to image forming device 100, and more particularly to print engine 110, to print an image. Another aspect of imaging driver 38 may be, for example, to facilitate the collection of scanned data from scanner system 150.

[0032] In some circumstances, it may be desirable to operate image forming device 100 in a standalone mode. In the standalone mode, image forming device 100 is capable of functioning without computer 30. Accordingly, all or a portion of imaging driver 38, or a similar driver, may be located in controller 102 of image forming device 100 so as to accommodate printing and/or scanning functionality when operating in the standalone mode.

[0033] FIG. 2 illustrates a schematic view of the interior of an example image forming device 100. For purposes of clarity, the components of only one of the imaging units 300 are labeled in FIG. 2. Image forming device 100 includes a housing 170 having a top 171, bottom 172, front 173 and rear 174. Housing 170 includes one or more media input trays 140 positioned therein. Trays 140 are sized to contain a stack of media sheets. As used herein, the term media is meant to encompass not only paper but also labels, envelopes, fabrics, photographic paper or any other desired substrate. Trays 140 are preferably removable for refilling. User interface 104 is shown positioned on housing 170. Using user interface 104, a user is able to enter commands and generally control the operation of the image forming device 100. For example, the user may enter commands to switch modes (e.g. color mode, monochrome mode), view the number of pages printed, etc. A media path 180 extends through image forming device 100 for moving the media sheets through the image transfer process. Media path 180 includes a simplex path 181 and may include a duplex path 182. A media sheet is introduced into simplex path 181 from tray 140 by a pick mechanism 132. In the example embodiment shown, pick mechanism 132 includes a roll 134 positioned at the end of a pivotable arm 136. Roll 134 rotates to move the media sheet from tray 140 and into media path 180. The media sheet is then moved along media path 180 by various transport rollers. Media sheets may also be introduced into media path 180 by a manual feed 138 having one or more rolls 139.

[0034] In the example embodiment shown, image forming device 100 includes four toner cartridges 200 removably mounted in housing 170 in a mating relationship with four corresponding imaging units 300 also removably mounted in housing 170. Each toner cartridge 200 includes a reservoir 202 for holding toner and an outlet port in communication with an inlet port of its corresponding imaging unit 300 for transferring toner from reservoir 202 to imaging unit 300. Toner is transferred periodically from a respective toner cartridge 200 to its corresponding imaging unit 300 in order to replenish the imaging unit 300. In the example embodiment illustrated, each toner cartridge 200 is substantially the same except for the color of toner contained therein. In one embodiment, the four toner cartridges 200 include yellow, cyan, magenta and black toner. Each imaging unit 300 includes a toner reservoir 302 and a toner adder roll 304 that moves toner from reservoir 302 to a developer roll 306. Each imaging unit 300 also includes a charging roll 308 and a photoconductive (PC) drum 310. PC drums 310 are mounted to substantially parallel to each other when the imaging units 300 are installed in image forming device 100. In the example embodiment illustrated, each imaging unit 300 is substantially the same except for the color of toner contained therein.

[0035] Each charging roll 308 forms a nip with the corresponding PC drum 310. During a print operation, charging roll 308 charges the surface of PC drum 310 to a specified voltage such as, for example, −1000 volts. A laser beam from LSU 112 is then directed to the surface of PC drum 310 and selectively discharges those areas it contacts to form a latent image. In one embodiment, areas on PC drum 310 illuminated by the laser beam are discharged to approximately −300 volts. Developer roll 306, which forms a nip with the corresponding PC drum 310, then transfers toner to PC drum 310 to form a toner image on PC drum 310. A metering device such as a doctor blade assembly can be used to meter toner onto developer roll 306 and apply a desired charge on the toner prior to its transfer to PC drum 310. The toner is attracted to the areas of the surface of PC drum 310 discharged by the laser beam from LSU 112.

[0036] An intermediate transfer mechanism (ITM) 190 is disposed adjacent to the PC drums 310. In this embodiment, ITM 190 is formed as an endless belt trained about a drive roll 192, a tension roll 194 and a back-up roll 196. During image forming operations, ITM 190 moves past PC drums 310 in a clockwise direction as viewed in FIG. 2. One or more of PC drums 310 apply toner images in their respective colors to ITM 190 at a first transfer nip 197. In one embodiment, a positive voltage field attracts the toner image from PC drums 310 to the surface of the moving ITM 190. ITM 190 rotates and collects the one or more toner images from PC drums 310 and then conveys the toner images to a media sheet at a second transfer nip 198 formed between a transfer roll 199 and ITM 190, which is supported by back-up roll 196.

[0037] A media sheet advancing through simplex path 181 receives the toner image from ITM 190 as it moves through the second transfer nip 198. The media sheet with the toner image is then moved along the media path 180 and into fuser 120. Fuser 120 includes fusing rolls or belts 122 that form a nip 124 to adhere the toner image to the media sheet. The fused media sheet then passes through exit rolls 126 located downstream from fuser 120. Exit rolls 126 may be rotated in either forward or reverse directions. In a forward direction, exit rolls 126 move the media sheet from simplex path 181 to an output area 128 on top 171 of image forming device 100. In a reverse direction, exit rolls 126 move the media sheet into duplex path 182 for image formation on a second side of the media sheet.

[0038] FIG. 3 illustrates an example embodiment of an image forming device 100′ that utilizes what is commonly referred to as a dual component developer system. In this embodiment, image forming device 100′ includes four toner cartridges 200 removably mounted in housing 170 and mated with four corresponding imaging units 300′. Toner is periodically transferred from reservoirs 202 of each toner cartridge 200 to corresponding reservoirs 302′ of imaging units 300′. The toner in reservoirs 302′ 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 reservoir 302′. In this embodiment, each imaging unit 300′ includes a magnetic roll 306′ that attracts the magnetic carrier beads having toner thereon to magnetic roll 306′ through the use of magnetic fields and transports the toner to the corresponding photoconductive drum 310′. Electrostatic forces from the latent image on the photoconductive drum 310′ strip the toner from the magnetic carrier beads to provide a toned image on the surface of the photoconductive drum 310′. The toned image is then transferred to ITM 190 at first transfer nip 197 as discussed above.

[0039] While the example image forming devices 100 and 100′ shown in FIGS. 2 and 3 illustrate four toner cartridges 200 and four corresponding imaging units 300, 300′, it will be appreciated that a monocolor image forming device 100 or 100′ may include a single toner cartridge 200 and corresponding imaging unit 300 or 300′ as compared to a color image forming device 100 or 100′ that may include multiple toner cartridges 200 and imaging units 300, 300′. Further, although imaging forming devices 100 and 100′ utilize ITM 190 to transfer toner to the media, toner may be applied directly to the media by the one or more photoconductive drums 310, 310′ as is known in the art. In addition, toner may be transferred directly from each toner cartridge 200 to its corresponding imaging unit 300 or 300′ or the toner may pass through an intermediate component such as a chute or duct that connects the toner cartridge 200 with its corresponding imaging unit 300 or 300′.

[0040] With reference to FIG. 4, toner cartridge 200 is shown according to one example embodiment. Toner cartridge 200 includes a body 204 that includes walls forming toner reservoir 202 (FIGS. 2 and 3). In the example embodiment illustrated, body 204 includes a generally cylindrical wall 205 and a pair of end walls 206, 207. However, body 204 may include any suitable shape or dimensions. In the embodiment illustrated, end caps 208, 209 are to mounted on end walls 206, 207, respectively such as by suitable fasteners (e.g., screws, rivets, etc.) or by a snap-fit engagement. An outlet port 210 is positioned on a bottom portion of body 204 such as near end wall 206. Toner is periodically delivered from reservoir 202 through outlet port 210 to reservoir 302 of imaging unit 300 to refill reservoir 302 as toner is consumed by the printing process. As desired, outlet port 210 may include a shutter or a cover that is movable between a closed position blocking outlet port 210 to prevent toner from flowing out of toner cartridge 200 and an open position permitting toner flow. Toner cartridge 200 includes one or more agitators (e.g., paddles, augers, etc.) to stir and move toner within reservoir 202. In one embodiment, the agitator(s) are driven by one or more rotatable shafts positioned within reservoir 202. In the example embodiment illustrated, a drive element 212, such as a gear or other form of drive coupler, is positioned on an outer surface of end wall 206. A portion of drive element 212 is exposed through end cap 208 in order to allow drive element 212 to receive rotational force from a corresponding drive component in the image forming device when toner cartridge 200 is installed in the image forming device. The rotatable shaft(s) within reservoir 202 may be connected directly or by one or more intermediate gears to drive element 212.

[0041] With reference to FIG. 5, toner cartridge 200 is shown with end cap 208 removed to more clearly illustrate the outer side of end wall 206. In the example embodiment illustrated, toner cartridge 200 includes a gear train 214, which may include one or more idler gears, positioned on end wall 206 beneath end cap 208 that leads from drive element 212 to a driven gear 216. In this embodiment, driven gear 216 receives rotational force from drive element 212 through gear train 214 and provides rotational force to an agitator positioned adjacent to outlet port 210 within reservoir 202 as discussed in greater detail below.

[0042] With reference to FIG. 6, the outer side of end wall 206 according to one example embodiment is shown with drive element 212, gear train 214 and driven gear 216 removed for clarity. FIG. 6 shows through holes 213 and 217 that receive rotatable shafts from reservoir 202 to permit the shafts to couple with drive element 212 and driven gear 216, respectively. Through holes 213 and 217 each include a gasket or the like to seal the interfaces between end wall 206 and the rotatable shafts so that toner from reservoir 202 does not leak from through holes 213 and 217. Although two through holes are shown in FIG. 6, any number of through holes may be present depending on the number of rotatable shafts in reservoir 202 requiring a connection to a drive element on end wall 206.

[0043] Toner cartridge 200 includes a vent 220 that permits the introduction of outside air into reservoir 202 in order to maintain nearly atmospheric pressure in reservoir 202. This prevents the low pressure or vacuum-like condition that may occur when toner exits toner cartridge 200 without air entering to fill the void. Vent 220 includes an inlet opening 222 positioned on the outer side of end wall 206. With reference to FIG. 7, the inner side of end wall 206 is shown. An outlet opening 224 (shown in dashed lines) in communication with inlet opening 222 is positioned on the inner side of end wall 206. For simplicity, in this embodiment, outlet opening 224 and inlet opening 222 are substantially aligned with each other; however, they may be offset and connected by a channel or duct as desired. In one embodiment, inlet opening 222 and outlet opening 224 are on the order of 3 mm to 4 mm in diameter. Inlet opening 222 and outlet opening 224 are shown as circular but may be any suitable shape. Vent 220 includes a one-way check valve that permits air to enter reservoir 202 from outside toner cartridge 200 and prevents toner from escaping reservoir 202 through vent 220. For example, in the embodiment shown, a flap formed from flexible plastic film commonly referred to as a reed valve 226 covers outlet opening 224. For example, reed valve 226 may be formed from a polyethylene terephthalate (PET) material such as MYLAR® available from DuPont Teijin Films, Chester, Va., USA. The flexible plastic film may be adhered to end wall 206, for example, using adhesive and/or stakes. In operation, when the air pressure in reservoir 202 is less than the atmospheric pressure, the flap of reed valve 226 flexes away from the inner side of end wall 206 to permit air to enter reservoir 202 from outside toner cartridge 200 through vent 220. In the example embodiment illustrated, reed valve 226 flexes about pivot line 227. In the embodiment illustrated, outlet opening 224 is positioned in an uppermost portion of reservoir 202 so that during operation of toner cartridge 200 the toner level will generally be below outlet opening 224 so that the toner does not restrict air flow through vent 220. Although inlet opening 222 and outlet opening 224 are illustrated as positioned on end wall 206 in the example embodiment illustrated, it will be appreciated that vent 220 including inlet opening 222 and outlet opening 224 may be positioned at any suitable location on toner cartridge 200 including, for example, cylindrical wall 205.

[0044] With reference to FIGS. 6 and 8, in one embodiment, vent 220 includes an air filter 228 positioned at inlet opening 222 to collect any small amount of toner that leaks past reed valve 226 of vent 220. In the embodiment shown, air filter 228 is positioned around inlet to opening 222 and is sandwiched between the outer side of end wall 206 and the inner side of end cap 208. In this manner, end cap 208 prevents toner from escaping air filter 228. In operation, the amount of air flow through vent 220 depends on the pressure differential between reservoir 202 and atmospheric pressure, the sizes of inlet opening 222 and outlet opening 224 and the resistance to air flow caused by air filter 228 (if present) and the one-way valve such as reed valve 226.

[0045] With reference back to FIG. 7, toner cartridge 200 includes a vent 230 that permits relatively high pressure air from reservoir 302 of imaging unit 300 to flow into the air cavity above the toner stored in reservoir 202. This prevents a large pressure gradient from forming between reservoir 302 and reservoir 202. Such a pressure gradient may restrict the flow of toner from reservoir 202 to reservoir 302. Without vent 230, air entering outlet port 210 from imaging unit 300 may not be able to flow to reservoir 202 because the air flow may be restricted by toner being fed to outlet port 210. Vent 230 includes an inlet opening 232 positioned on the inner side of end wall 206 next to outlet port 210 to receive air entering outlet port 210 from imaging unit 300. Inlet opening 232 is in communication with an outlet opening 234 (shown in dashed lines) positioned on an inner side of end wall 206. In the example embodiment illustrated, inlet opening 232 is in communication with outlet opening 234 via a channel or duct 236 (see FIG. 6) that runs through end wall 206. In one embodiment, inlet opening 232 and outlet opening 234 are on the order of 3 mm to 4 mm in diameter. Inlet opening 232 and outlet opening 234 are shown as circular but may be any suitable shape. Vent 230, like vent 220, includes a one-way check valve that permits air to enter reservoir 202 and prevents toner from escaping reservoir 202 through vent 230. In the example embodiment shown, a reed valve 238 covers outlet opening 234. When the air pressure in reservoir 202 is less than the air pressure at outlet port 210 as a result of a relatively high pressure condition in reservoir 302 of imaging unit 300, the flap of reed valve 238 flexes away from the inner side of end wall 206 to permit air to enter reservoir 202 through vent 230. In the example embodiment illustrated, reed valve 238 flexes about pivot line 239. In the example embodiment illustrated, reed valve 238 and reed valve 226 are formed from a single piece of plastic film 260 for simplicity; however, reed valves 226 and 238 may also be formed separately as desired. In the embodiment illustrated, film 260 includes an adhesive portion 262 that adheres film 260 to end wall 206 and non-adhesive portions 264 that form the flaps of reed valves 226 and 238. In this embodiment, outlet opening 234 is positioned in an uppermost portion of reservoir 202 so that during operation of toner cartridge 200 the toner level will generally be below outlet opening 234 so that the toner does not restrict air flow through vent 230. Although inlet opening 232 and outlet opening 234 are illustrated as positioned on end wall 206 in the example embodiment illustrated, it will be appreciated that vent 230 including inlet opening 232 and outlet opening 234 may be positioned at any suitable location on toner cartridge 200 including, for example cylindrical wall 205.

[0046] With reference back to FIG. 6, in the example embodiment illustrated, duct 236 includes a recess 240 (shown in dashed lines) in the outer side of end wall 206 that connects inlet opening 232 with outlet opening 234, which are shown in dashed lines in FIG. 6. In one embodiment, a projection 242 corresponding to recess 240 is formed on the inner side of end wall 206 as shown in FIG. 7. As desired, duct 236 may be formed as a recess in the inner side of end wall 206 instead of the outer side of end wall 206. In the example embodiment illustrated, duct 236 includes a seal 244 that covers recess 240 so that air passing through recess 240 does not escape. FIG. 9 shows the outer side of end wall 206 shown in FIG. 6 with seal 244 removed to more clearly illustrate recess 240. The seal may be composed of any suitable material such as a flexible plastic film adhesively adhered to end wall 206 (e.g., MYLAR® mentioned above). Alternatively, duct 236 may be formed as a void within the material that makes up end wall 206, which may be, for example, a substantially rigid molded plastic. Further, it will be appreciated that duct 236 may take many other shapes and forms such as a rubber or plastic tube or pipe, etc. so long as duct 236 creates an air path from inlet opening 232 to outlet opening 234. In the example embodiment illustrated, duct 236 runs from a corner of end wall 206 where inlet opening 232 is located upward along a side portion of end wall 206 toward the top of body 204. Duct 236 then turns and runs toward a central, uppermost portion of end wall 206 where outlet opening 234 is located. However, it will be appreciated that duct 236 may take any suitable path to connect inlet opening 232 to outlet opening 234 including passing within and/or outside of reservoir 202 through any of walls 205, 206, 207.

[0047] FIG. 10 shows a portion of reservoir 202 of toner cartridge 200 according to one example embodiment. In this embodiment, an auger 246 is positioned in a lower portion of reservoir 202 above outlet port 210 and has an axis of rotation generally orthogonal to end wall 206. Auger 246 receives rotational force from driven gear 216 to feed toner from reservoir 202 out of outlet port 210. In one embodiment, a deflector 248 separates a portion of auger 246 along the length of auger 246 from the toner stored in reservoir 202 to permit auger 246 to meter the amount of toner that exits outlet port 210. FIG. 11 is a perspective view from the interior of reservoir 202 looking toward end wall 206 and cylindrical wall 205 with deflector 248 removed to more clearly illustrate inlet opening 232 (shown in dashed lines). In this embodiment, inlet opening 232 is positioned adjacent to auger 246 (e.g., just above auger 246 as illustrated) and separated from the toner stored in reservoir 202 by deflector 248. In this position, air from reservoir 302 is permitted to pass up through outlet port 210 and into inlet opening 232. The air may then travel through duct 236 to open reed valve 238 and exit outlet opening 234. In the example embodiment illustrated, a foam seal 250 is positioned over inlet opening 232 to allow air to enter inlet opening 232 but reduce the amount of toner entering inlet opening 232. Seal 250 may also be positioned to prevent toner from passing between the inside of end wall 206 and deflector 248. FIG. 12 shows reservoir 202 with deflector 248 and seal 250 removed to more clearly illustrate the position of auger 246 relative to outlet port 210 according to one embodiment. In operation, the amount of air flow through vent 230 depends on the pressure differential between reservoir 302 and reservoir 202, the sizes of inlet opening 232 and outlet opening 234 and the resistance to air flow caused by duct 236, the one-way valve such as reed valve 238 and seal 250 (if present).

[0048] Some embodiments of toner cartridge 200 include a venting system that includes both vent 220 and vent 230. In these embodiments, the air pressure in reservoir 202 is the greater of atmospheric pressure and the pressure of reservoir 302, which is typically substantially equal to or greater than atmospheric pressure. Vent 230 permits air pressure from reservoir 302 above atmospheric pressure to pass to reservoir 202 in order to maintain pressure equilibrium between reservoir 202 and reservoir 302. Vent 220 prevents the air pressure in reservoir 202 from falling below atmospheric pressure. In this manner, the combination of vents 220 and 230 promotes consistent toner flow from reservoir 202 out of outlet port 210. Further, it may be desired to measure the amount of toner remaining in reservoir 202 based on the number of revolutions of the toner agitator(s) (e.g., auger 246) within reservoir 202 (e.g., based on the number of revolutions of drive element 212). For example, the amount of toner consumed may be determined by multiplying the number of revolutions by an amount of toner consumed per revolution (which may be determined empirically). The amount of toner remaining may then be determined by subtracting the amount of toner consumed from the initial amount of toner present to in reservoir 202. If the toner is kept at near constant density (e.g., by fluffing or agitating the toner) and the air pressure within reservoir 202 is controlled, it has been found that the flow rate of toner from reservoir 202 is substantially constant when the toner is metered through outlet port 210 using auger 246 and deflector 248. The combination of vent 220 and vent 230 helps maintain a constant and predictable flow rate of toner from toner cartridge 200 and, as a result, permits the measurement of the amount of toner remaining in reservoir 202 based on agitator revolutions with improved accuracy in comparison with a reservoir 202 that experiences a vacuum-like condition encountered as toner is removed from reservoir 202 or that experiences a large pressure differential with a corresponding reservoir 302.

[0049] FIGS. 13-15 illustrate another example embodiment of vents 220 and 230 labeled vents 220′ and 230′. Specifically, FIGS. 13 and 15 show the inner side of an end wall 206′ and FIG. 14 shows the outer side of end wall 206′. FIGS. 13 and 15 show outlet opening 224′ of vent 220′ and both inlet opening 232′ and outlet opening 234′ of vent 230′ positioned on the inner side of end wall 206′. FIG. 14 shows inlet opening 222′ of vent 200′ positioned on the outer side of end wall 206′. In this example embodiment, duct 236′ of vent 230′ includes a recess 240′ in the inner side of end wall 206′ as shown in FIGS. 13 and 15. In this example, a projection 242′ corresponding to recess 240′ is formed on the outer side of end wall 206′ as shown in FIG. 14. A seal 244′ covers recess 240′ to form duct 236′. In this example embodiment, a single piece of flexible plastic film 260′ may be used to form seal 244′ as well as reed valve 226′ of vent 220′ and reed valve 238′ of vent 230′ thereby reducing manufacturing complexity and cost. For example, film 260′ may include an adhesive portion 262′ that adheres film 260′ to end wall 206 and non-adhesive portions 264′ that form the flaps of reed valves 226′ and 238′. In this embodiment, reed valve 226′ flexes about pivot line 227′ and reed valve 238′ flexes about pivot line 239′. As illustrated in FIG. 15, reed valves 226′ and 238′ flex open from left to right as viewed in FIG. 15. This allows a toner agitator 270′ to pass along the inner surface of end wall 206′ in a counterclockwise direction as viewed in FIG. 15 with reduced risk that the agitator 270′ will inadvertently open reed valve 226′ or 238′ thereby preventing toner leakage through vent 220′ or 230′. If, on the other hand, toner agitator 270′ contacts reed valve 226′ or 238′ in the direction that reed valve 226′ or 238′ flexes open, the agitator 270′ may tend to inadvertently push reed valve 226′ or 238′ open as the agitator 270′ passes or, worse yet, bend or deform reed valve 226′ or 238′ permanently opening the valve and allowing toner to leak through vent 220′ or 230′.

[0050] The foregoing description illustrates various aspects and examples 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. For example, aspects of vent 230 may be combined with aspects of vent 230′, etc.